GEOGRAPHIC INFORMATION SYSTEMS, SPATIAL DATA
ANALYSIS, AND DECISION MAKING IN GOVERNMENT
R. .
T om lin son
J u ly , 1974
Roger Tomlinson completed this PhD thesis at UCL in 1974. It was based on his experience
during the 1960s in creating the Canada Geographic Information System (CGIS) for the
Canada Land Inventory. The CGIS is now widely recognised as the world's first integrated
geographical information system capable of mapping and analysing geographical
information and applying it to a comprehensive range of planning and management
functions.
Roger had come to UCL as a result of a chance meeting with Professor Terry Coppock at the
1964 International Geographical Union meeting in London. Terry was interested in
automating land use mapping, and saw the potential value of documenting the CGIS
experience.
By the time contact with UCL was re-established in 1970, Terry had moved on to Edinburgh,
and the task of focusing Roger’s experience and enthusiasm into an academic thesis fell to
me, a young economic geographer with an interest in planning and spatial analysis. The
thesis documented Roger’s experience in developing the CGIS, laying out the principles
required to apply geographical information systems more generally. It was, however, more
than an account of technical requirements. Roger always insisted that GIS applications
require geographical expertise and should focus on applying geographical knowledge and
understanding to the analysis of real world problems.
GIS developments at the time were limited by computing capacities, which now seem
extraordinarily limited, but the thesis was able to develop general principles from the land
use mapping problems encountered in the CGIS. Roger knew that computing capacity would
inevitably expand, although even he, I suspect, did not anticipate the speed with which this
would occur after the 1970s. Remarkably, this was when the approaches he set down in the
early 1970s came into their own, developed through his seminal book, Thinking about GIS:
Geographical Information System Planning for Managers, now in its fifth edition and
including a translation into Chinese.
From the work summarised in this thesis, Roger’s later achievements in the application of
GIS were summarised in the May 2001 citation for his award of the Order of Canada:
Recognized as the 'father o f GIS', he pioneered its uses worldwide to collect, manage and
manipulated geographical data, changing the face o f geography as a discipline. His work
established Canada's reputation fo r excellence in the emerging and continually expanding
field o f geo-spatial analysis. Governments and scientists around the world have turned to
him to better understand our environment and changing patterns o f land use, to better
manage urban development and our precious natural resources.
Peter Wood
July 2017
1
T he ap p lication of e le c tr o n ic com puting m ethods
and tech n iq u es to the sto r a g e , com p ilation , and
a s s e s s m e n t of m apped data
R o g er F . T o m lin so n , B. S c . , M. Sc.
A t h e s is su b m itted in candidature
fo r th e D eg ree o f D octor of P h ilo so p h y
U n iv e r sity o f London
Ju ly, 1974
2
ABSTRACT
Manual and co m p u ter-a id ed tech n iq u es fo r handling lo c a tio n -s p e c ific data
a r e view ed , not in te r m s of th e ir a b ility to prod uce m a p s, but in the b road er
r o le o f sto rin g , m anipulating, and d isp la y in g such, data.
T h e c h a r a c te r is t ic s , s o u r c e s , and. sup p ly of s p a tia l data a r e d isc u sse d .
M anual tech n iq u es f o r handling mapped, d ata a r e exam in ed a s th e b en ch ­
m a rk s o f tra d itio n a l c a p a b ility a g a in st which, th e new co m p u ter-a id ed
m eth od s m u st b e judged.
T h e sto r a g e of s p a tia l data in e le c tr o n ic co m p u ters i s re v iew ed .
G eneral
c a te g o r ie s o f c o m p u ter-a id ed tec h n iq u e s b a s e d o n th e ir s to r a g e fo rm a t a r e
e xam in ed and th e ir c h a r a c te r is t ic s a r e illu str a te d w ith s p e c if ic ex a m p le s.
T h e C anada G eograp hic In form ation S y ste m , w h o se d evelopm ent w a s
in itia te d and d ir e c te d b y th e author, i s ex a m in e d in t h is con text.
T h e cu rr en t o v e r a ll a b ility to h an d le s p a tia l d ata i s a n a ly sed w ith in a f r a m e ­
w o rk o f data c h a r a c te r is tic s and s y s t e m c a p a b ilitie s .
T h e c a te g o r ie s o f
d ifferen t c a p a b ilitie s e m e r g e , t h e ir in stitu tio n a l back grou nd s a r e m ade
c le a r , but q u e stio n s a r e r a is e d ab out th e w a y in w h ich th e tech n iq u es a re
d evelop in g, th e ir u s e f u ln e s s , and th e fu tu r e p r o g r e s s o f such g eograph ic
in fo rm a tio n s y s te m s .
F o r m a l s p a tia l a n a ly s is and g o v er n m en t d e c is io n m ak in g a r e exam ined in
t e r m s o f th e ir u se of data.
T h e con trib u tion o f e x is tin g g eo g ra p h ic
in fo rm a tio n s y s te m s to th e s e p r o c e s s e s i s c r it ic a lly ap p ra ised .
W ithin th e d is c ip lin e o f g eograp h y, it: i s s u g g e ste d th at th e m utual d ev elo p ­
m ent of fo r m a l s p a tia l m o d e ls and g eo g r a p h ic in fo rm a tio n s y s t e m s w ill
le a d to fu ture b e n e fic ia l s h if t s o f e m p h a sis in both f ie ld s o f endeavour.
W ithin govern m en t, ch a n g es in o p era tio n a l p ro ce d u re and th e p o s s ib ility
o f ch an ges in th e d e c isio n -m a k in g p r o c e s s a r e d is c u s s e d .
O rganization al
s tr u c tu r e s to fa c ilita te th e u s e o f data, s t o r e s a r e p ostu la ted .
It i s apparent
that th e d evelopm ent o f geograp h ic in form ation s y s t e m s cannot s e n sib ly
p r o c e e d fu rth er in is o la tio n , but. m u st b e undertaken a s an in te g r a l part o f
th e v e r y la r g e str u c tu r e o f d ata gath erin g, d ata a n a ly s is , and d e c isio n
m aking.
3
ACKNOWLEDGEMENTS
I w ould lik e to thank D r. P . W ood fo r th e ad vice and en co u ra g em en t he
s o g e n e r o u s ly p rovid ed during th e p rep a ra tio n o f th is th e s is .
A p p recia tio n i s a ls o exten d ed t o 'P r o fe s s o r W. M ead fo r th e m any h elp fu l
d is c u s s io n s during m y r e sid e n c e a t th e D ep artm en t of G eography,
U n iv e r s ity C o lle g e, London.
T he fin a n c ia l a s s is ta n c e p rovid ed b y th e Canada C oun cil i s g r a te fu lly
ack n ow led ged .
T o th e m any c o lle a g u e s and fr ie n d s w ho h a v e in d ivid u ally and jo in tly
tak en p art in d is c u s s io n s and p rovid ed a s s is t a n c e in m any w a y s, I
exten d m y h e a rtfelt th ank s.
R. P . T.
Ottaw a, 1974
4
T A B L E O F C O N T EN TS
P age
A b s t r a c t ...............................................................................................................................
2
A c k n o w le d g e m e n ts ..........................................................................................................
3
T a b le of C o n t e n t s ................... ........... ............................................................................
4
L i s t of F i g u r e s .................................... ............................................................................ 8
L i s t of T a b l e s ...................................................................................................................
11
C h a p te r 1
I n t r o d u c t i o n ..............................................................................................
12
R eview o f l i t e r a t u r e .........................................................................
C o n trib u tio n a n d c o n te x t of t h e s i s ..................................................
T h e s is s t r u c t u r e ..............................................................................
14
17
18
C h a r a c t e r i s t i c s an d A v a ila b ility of
L o c a tio n -S p e c if ic D a ta .........................................................................
26
C h a r a c t e r i s t i c s of lo c a tio n - s p e c if ic d a t a ....................................
C o n c e p ts o f s p a c e .........................................................................
S p a tia l la n g u a g e s ...........................................................................
S p a tia l d e s c r ip tio n .........................................................................
S p a tia l d a ta f o r m a t .......................................................................
T y p e s of lo c a tio n i d e n t i f i e r ......................................................
S upply a n d a v a ila b ility of d a ta ....................................................
S o u rc e c h a r a c t e r i s t i c s ................................................................
P e r c e i v e d n e e d f o r d a t a ....................................................
G a th e rin g c o n s t r a i n t s .........................................................
G a th e rin g c a p a b i l i t y ...........................................................
(a) G a th e rin g te c h n iq u e s ......................................
(b) A v a ila b le r e s o u r c e s ........................................
R e s u ltin g d a ta c h a r a c t e r i s t i c s ................................... ...........
V a lid ity c o n s t r a i n t s ...........................................................
P h y s i c a l h a n d lin g c h a r a c t e r i s t i c s ...............................
U se c o n s t r a i n t s ....................................................................
R e s u ltin g s p a ti a l d a ta su p p ly and a v a i l a b i l i t y .................
S u m m a r y ......................................................................................................
26
27
28
29
30
34
37
37
37
40
43
43
48
49
50
53
55
56
58
M anual T e c h n iq u e s f o r H a n d lin g M apped and O th e r
L o c a tio n -S p e c ific D a ta ....................................................................
59
C h a p te r 2
C h a p te r 3
Im a g e m a n ip u la tio n ................................................................................ .
S c a le c h a n g e .....................................................................................
D is to r tio n e lim in a tio n .............................................................
N o n lin e a r d is to r tio n e lim in a tio n an d m ap
p r o je c ti o n c h a n g e ...........................................................................
61
62
62
63
5
Page
C h a p te r 4
C h a p te r 5
G ro u p in g .............................................................
M e rg e an d d i s s o l v e .............................................
E d g e m a t c h ...............................................
C e n tro id a l l o c a t i o n .................................................
C o n to u r in g ............................
G e n e ra liz a tio n . . . ..............................................................
D ata e x t r a c t i o n ............ ............................................
D a ta s e l e c t i o n .............................................................
R ea d in g . ............................................................
S e a rc h a n d id e n tif ic a tio n ..................................................
D a ta r e t r i e v a l ..................................................................
T r a n s f e r ....................................................................
M e a s u re m e n t a n d c o m p a r is o n ......................................
S u m m a ry ........................................... .......................................
63
64
64
64
65
65
66
67
67
68
69
69
73
78
C u r r e n t C o m p u te r-A id e d S y s te m s f o r H an d lin g M apped
a n d O th e r L o c a tio n -S p e c if ic D a ta ..................................................
82
B a s ic c o n s id e r a tio n s ............................................................................
C o d e s f o r n o n - g ra p h ic s p a ti a l d a t a ........................................
F i l e s t r u c t u r e s f o r c o d e d n o n - g ra p h ic s p a ti a l d a t a . . . . . .
F i l e s e q u e n c in g .......................... ....................................................
F i l e li n k a g e .....................................................................................
F i l e r e c o r d l a y o u t .......................................................................
F i l e in fo r m a tio n c o n t e n t...........................................................
R e la tio n s h ip b e tw e e n ty p e of s to r a g e f o r m a t f o r n o n ­
g r a p h ic s p a ti a l d a ta a n d c u r r e n t s y s te m s f o r h a n d lin g
s p a ti a l d a t a ..............................................................................................
A r b i t r a r y r e g u l a r - a r e a c a te g o r y of s y s t e m s ......................
A r b i t r a r y r e g u l a r - a r e a s y s t e m s - T y p e 1 .....................
LU N R s y s t e m - E x a m p le of T y p e 1 of th e a r b i t r a r y
r e g u l a r - a r e a c a t e g o r y ........................................ ..
A r b i t r a r y r e g u l a r - a r e a s y s t e m s - T y p e 2 .....................
SYM A P s y s t e m - E x a m p le of T y p e 2 o f th e
a r b i t r a r y r e g u l a r - a r e a c a te g o r y ...........................................
P o in t d a ta c a te g o r y of s y s t e m s ......................................................
G RDSR s y s t e m - E x a m p le o f p o in t d a ta c a te g o r y . . . .
L in e s e g m e n t c a te g o r y o f s y s t e m s ...............................................
D IM E s y s t e m - E x a m p le of. lin e s e g m e n t c a t e g o r y . . .
A U T O M A P s y s t e m - E x a m p le of lin e se g m e n t
c a t e g o r y ...................................................................... .................. ..
S u m m a r y ...................................................................................................
84
85
90
91
92
94
95
122
126
C o m p u te r-A id e d S y s te m s U n d er D ev elo p m en t f o r
H an d lin g M apped an d O th e r L o c a tio n -S p e c ific D a t a ............
130
I r r e g u l a r poly g o n c a te g o r y of s y s t e m s ......................................
130
95
98
99
99
103
105
109
111
115
116
6
Page
C h a p te r 6
C h a p te r 7
T y p e s o f i r r e g u l a r p o ly g o n s y s t e m s ..............................
C o a r s e p o ly g o n s y s t e m s : th e e x a m p le of P I O S ..............
F in e p o ly g o n s y s t e m s : th e e x a m p le of C G IS. . .
C u r r e n t h a r d w a r e - r e l a t e d d e v e lo p m e n ts in in p u t,
m a n ip u la tio n , a n d o u tp u t c a p a b i l i t i e s ..........................
In p u t t e c h n i q u e s ................................. ...........
C u r r e n t p o in t /li n e d i g i t i z i n g .................................
I n te r a c tiv e p o in t / l i n e d i g i t i z i n g ............................
A u to m a tic li n e fo llo w in g .................................
S c a n n in g ................................................................ ..
D a ta b a s e m a n ip u la tio n t e c h n iq u e s ........................................
I n te r a c ti v e m a n ip u la tio n of s p a ti a l d a ta b a s e
M a n ip u la tio n o f E R T S n u m e r ic a l ly co d e d im a g e s .
O u tp u t d e v ic e s ............................... .................................................
M u lti- f o r m a t s y s t e m s .......................................................
S u m m a r y ................................................................
168
168
168
171
172
173
175
175
178
179
180
184
A n a ly s is of S p a tia l D a ta H an d lin g C a p a b ility in T e r m s of
D a ta C h a r a c te r a n d A v a ila b ility : A F r a m e w o r k f o r
D e s c r ip tio n of G e o g ra p h ic I n fo rm a tio n S y s t e m s ............
187
A n a ly s is o f f r a m e w o r k ..........................................................................
L o c a tio n i d e n t i f i e r s .......................................................................
V o lu m e of r e l a t e d d a t a ................................................................
M a n ip u la tio n f a c i l i t i e s
......... ..
S y n t h e s i s ........................................... .................. .................... ..................
187
188
192
194
210
G e o g ra p h ic In fo rm a tio n S y s te m s , S p a tia l D a ta A n a ly s is ,
a n d D e c isio n M ak in g in G o v e r n m e n t ............................................. 221
F o r m a l s p a ti a l a n a ly s is r e l a t e d t o d a ta u s e ...............................
G o v e rn m e n t d e c is io n m a k in g r e l a t e d to d a ta u s e . ...................
C o n trib u tio n of d if f e re n t ty p e s of e x is tin g g e o g ra p h ic
in fo rm a tio n s y s t e m to f o r m a l s p a t i a l a n a ly s is a n d to
d e c is io n m a k in g in g o v e r n m e n t.......................... ..............................
O v e r a ll v a lu e of e x is tin g g e o g ra p h ic in fo rm a tio n s y s te m s .
C h a p te r 8
143
144
152
223
232
240
251
F u tu r e D e v e lo p m e n t o f G e o g ra p h ic In fo rm a tio n S y s t e m s .. . 253
D e v e lo p m e n t of s y s t e m c a p a b ili tie s a s s u m in g p r e s e n t
c o m p u te r c h a r a c t e r i s t i c s .....................................................................
I m p ro v e m e n ts of th e n o n - g ra p h ic d a ta b a s e .....................
I m p ro v e m e n ts i n m a n ip u la tiv e c a p a b i l i t y ..........................
Im p a c t of c o m p u te r d e v e lo p m e n t o n g e o g ra p h ic
in f o rm a tio n s y s t e m s ..............................................................................
D e v e lo p m e n t of g e o g ra p h ic in fo rm a tio n s y s t e m s in
c o n te x t of th e o v e r a l l v a lu e of s t o r e s of s p a tia l
in f o rm a tio n ...................... .................. ........................................................
253
253
255
259
260
7
Page
F u tu r e d e v e lo p m e n ts w ith in th e d is c ip lin e of
g e o g r a p h y ...................................................................................................
F u tu r e d e v e lo p m e n ts r e l a t e d to d e c is io n m a k in g
in g o v e rn m e n t
In s titu tio n a l d a ta li n k a g e s ....................................................
D e s ig n of f o r m a l s p a ti a l m o d e ls ...........................................
P o s t - u n iv e r s i ty t r a n s f e r of te c h n o lo g y to
d e c is io n m a k e r s ................................................................
I n te r a c ti o n b e tw e e n d a ta g a t h e r e r s a n d d a ta u s e r s . . .
I n te r a c ti o n b e tw e e n d a ta s p e c i a l i s t s a n d d e c is io n
m a k e r s ........................................................................................
S u m m a r y ..................................................................................................
263
267
271
273
274
276
277
284
R e f e r e n c e s ........................................................................................................................... 286
A p pendix - T e c h n ic a l d e s c r ip tio n of C a n a d a G e o g ra p h ic I n fo rm a tio n
S y ste m . ......................................................................................................... 306
P u b lis h e d C o n trib u tio n - A G e o g ra p h ic In f o rm a tio n S y s te m f o r
R e g io n a l P la n n i n g .................................................. fo llo w in g p ag e 444
8
LIST O F F IG U R E S
F ig u r e
T itle
Page
1. 1
R e la tio n s h ip s b e tw e e n d a ta g a th e rin g , d a ta h a n d lin g ,
d a ta a n a ly s is , a n d d e c is io n m a k in g .............. ...........
12
2. 1
R e la tio n s h ip s b e tw e e n th e s p a ti a l d im e n s io n s of e n titie s
to b e r e c o r d e d , g ra p h ic a n d s y m b o lic r e c o r d s , an d th e
c h o ic e o f th e s to r a g e m e d ia . . . . . . . . . . . . . . . . . . . . . . . . . .
32
2. 2
C o m m o n lo c a tio n id e n tif i e r s in e x is tin g s e t s o f d a ta . . . . . . . . .
34
2. 3
V a r ia b le s th a t in flu e n c e th e c h a r a c te r a n d a v a ila b ility
of s p a ti a l d a ta g a th e r e d b y g o v e rn m e n ts ..............................................
37
2 .4
R e la tio n s h ip b e tw e e n h u m a n an d in s tr u m e n t c a p a b ilitie s
f o r s e n s in g a n d c a lib r a tin g s p a tia l d a ta ................................................
44
2 .5
M eth o d s o f s p a ti a l d a ta s e n s in g a n d r e c o r d i n g ..................................
46
2. 6
R e la tio n s h ip s b e tw e e n d a ta f o r m a t, r e c o r d f o r m a t, and
r e t r i e v a l p o s s i b i l i t i e s . ......................................................................... ..
54
3. 1
R e la tio n s h ip b e tw e e n ty p e of m a n u a l te c h n iq u e a n d tim e
u s e d . ....................................................................................................................
78
3. 2
R e la tio n s h ip b e tw e e n d a ta v o lu m e a n d tim e r e q u i r e d f o r
d a ta m a n ip u la tio n an d e x tr a c tio n . ...................................... ............. ..
79
3. 3
R e la tio n s h ip s b e tw e e n m a n u a l te c h n iq u e s , v o lu m e o f d a ta ,
a n d tim e u s e d ......................................................................................................
79
3 .4
R e la tio n s h ip b e tw e e n c o m p o n e n ts of m a n u a l te c h n iq u e s
a n d tim e u s e d ...........................................................................................
81
4. 1
D e v e lo p m e n ts in d a ta flo w ............................................................................
84
4. 2
C o m p o n e n ts o f c o m p u te r s to r a g e ........................................ .....................
85
4. 3
D a ta in p u t a n d r e t r i e v a l p a th s ..................................... ..............................
86
4 .4
R e la tio n s h ip b e tw e e n m e tr ic an d to p o lo g ic a l c o d e s .........................
88
4 .5
R a n g e o f co d in g r e l a te d to e x p r e s s io n of s p a ti a l
r e l a ti o n s h i p s w ith in a d a ta s e t. . . . . . . . . . .......................
90
4. 6
O p e ra tio n s p o s s ib le on s p a tia l d a ta co d e d a s c o o rd in a te
p o in ts ......................................................................................................................
96
4. 7
R e la tio n s h ip b e tw e e n r e a l - w o r l d d a ta e le m e n ts a n d co d ed
n o n - g r a p h ic s to r a g e f o r m a ts .......................................................... ............
97
4. 8
T y p e s of m a n ip u la tio n c a p a b ility in s y s t e m s b a s e d o n
s to r a g e f o r m a ts u s in g a r b i t r a r y r e g u l a r a r e a s a s a
fu n c tio n of c e ll s iz e an d c h a r a c t e r i s t i c s o f s o u r c e d a ta
e l e m e n t s ............... .............................................................................................
98
9
F ig u r e
T itle
Page
5. 1
S am p le m a p of 15 i r r e g u l a r p o ly g o n s................
133
5. 2
C e n tr o id c o o rd in a te s (15 d a ta p o in ts ). . . ..........
133
5. 2. 1
5. 3
5. 3. 1
5 .4
5 .4 . 1
5. 5
5 . 5. 1
5. 6
5. 6. 1
5. 7
F if te e n a r b i t r a r y r e g u l a r - a r e a c e lls .
N e tw o rk r e p r e s e n t a ti o n (32 d a ta p o in ts ) .....................................
T h ir ty - tw o a r b i t r a r y r e g u l a r - a r e a c e l l s ...................................
133
134
134
C o a r s e poly g o n r e p r e s e n t a ti o n (98 d a ta p o in ts )................................ 134
N in e ty -e ig h t a r b i t r a r y r e g u l a r - a r e a c e lls . . .
F in e poly g o n r e p r e s e n t a ti o n : 10 p o in ts p e r in .
(330 d a ta p o in ts).
134
135
T h r e e h u n d re d a n d t h i r t y a r b i t r a r y r e g u l a r - a r e a c e lls .......... 135
F in e poly g o n r e p r e s e n t a ti o n : 50 p o in ts p e r in .
(1, 650 d a ta p o in ts ) ......................................................................................
O ne th o u s a n d , s ix h u n d re d a n d fif ty a r b i t r a r y
r e g u l a r - a r e a c e l l s ...................... . . . . . . ............................................
135
135
S am p le m a p w ith s in g le i r r e g u l a r poly g o n in d ic a te d ...................... 138
5. 7. 1
P o ly g o n b o u n d a ry a s s ig n e d to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (15 d a ta p o in ts) a s c e n tr o id c o o r d in a te s ............... 138
5. 7. 2
P o ly g o n b o u n d a ry a s s ig n e d to r e g u l a r g r id u s in g
s a m e d a ta v o lu m e (32 d a ta p o in ts) a s lin e n e tw o r k .................... 138
5. 7. 3
P o ly g o n b o u n d a ry a s s ig n e d to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (98 d a ta p o in ts) a s c o a r s e p o ly g o n .........................
139
5. 7 .4
P o ly g o n b o u n d a ry a s s ig n e d to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (330 d a ta p o in ts) a s fin e p o ly g o n s a t
10 p o in ts p er. in .............................................................. ...........................
139
5 . 7. 5
P o ly g o n b o u n d a ry a s s ig n e d to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (1, 650 d a ta p o in ts) a s fin e p o ly g o n s a t
50 p o in ts p e r in .......................................................................................... . 139
5 .8
5 .9
M a x im a l n e ig h b o u rh o o d of a p o in t in a m a t r i x ................................
141
neighbourds R e p r e s e n ta tio n of a n i r r e g u l a r p o ly g o n b y m a x im a l
141
5. 10
5 . 11
5. 12
5. 13
5. 14
CGIS: o v e r a l l s y s t e m c o n c e p t..................................................................
153
no-graphicves O p e ra tio n s in v o lv e d in CGIS p r o c e s s of g r a p h ic to
154
Image Data Set - Level 1
156
Descriptor Data Set - Level 1
157
S tr u c tu r e d D e s c r ip to r D ata S e t..........................................................
157
10
F ig u r e
T itle
Page
5. 15
In fo rm a tio n lo s s in r e l a ti o n to s iz e s of s to r a g e an d
o u tp u t e le m e n ts ................................................................................................ 180
5. 16
T r a n s f o r m a tio n s b e tw e e n s to r a g e an d o u tp u t f o r m a ts
u n d e r ta k e n b y ty p ic a l s y s t e m s ................................................................. 181
6. 1
A x e s of d e s c r ip tiv e f ra m e w o rk .. . . . .......................................................
6. 2
L o c a tio n id e n tif i e r s w ith r e l a t e d d a ta s e t s ........................................ 189
6. 3
C a te g o r ie s of v o lu m e of r e l a t e d d a ta w ith e x a m p le s of
ty p ic a l s y s t e m s ............................................................................... ...........
6 .4
M a n ip u la tio n f a c i li tie s a n d t h e i r r e l a t e d s y s t e m s .......................... 195
188
192
6 .5
E x a m p le o f th e m e rg e p r o c e s s ................................................................. 202
6. 6
In te r v is ib il ity b e tw e e n g iv e n p o in ts ....................................................... 203
6. 7
O v e rla y c o n d itio n w h e r e M ap B i s p a r t ia l ly o v e r la id
o n M ap A ....................................... ......................................... ........................... 205
6. 8
L o c a tio n id e n tif i e r s r e l a t e d to v o lu m e of r e l a te d d a ta ................. 211
6. 9
S y s te m m a n ip u la tio n f a c i l i t i e s r e l a t e d to lo c a tio n
id e n tif i e r s ........................................................................................................... 213
6. 10
S y s te m m a n ip u la tio n f a c i l i t i e s r e l a t e d to v o lu m e of
d a ta p e r lo c a tio n ............. . ............................................................................. 215
6. 11
D ia g o n a l OS a s a v e c to r of p o te n tia l c a p a b ility of s y s t e m
f il e s t r u c t u r e s ................................................................................................... 218
7. 1
R e la tio n s h ip s b e tw e e n d a ta , a n a ly s is , an d d e c is io n ..................... 222
7. 2
T y p ic a l s e t of d e c is io n - m a k in g i n s t i t u t i o n s . ................................. .. 233
7. 3
T y p ic a l ty p e s of d e c is io n w ith in n a tio n a l, r e g io n a l, and
l o c a l in s ti tu ti o n s ............................................................................................ 233
7 .4
S im p lis tic co n c e p t of p o lic y , m a n a g e m e n t, an d a d m in is t r a t i v e d e c is io n le v e ls in n a tio n a l, re g io n a l, o r lo c a l
g o v e rn m e n t in a p a r l ia m e n ta r y s y s te m . ........................................ . 236
7 .5
C a te g o r ie s of g e o g ra p h ic in fo r m a tio n s y s t e m s , t h e ir
c h a r a c t e r i s t i c s , p r im a r y u tility , a n d p r im a r y u s e ...................... 241
8. 1
C o m p le x itie s in th e r e l a ti o n s h i p s b e tw e e n d e c is io n m a k in g ,
g e o g ra p h ic in fo rm a tio n s y s t e m s , an d s p a tia l a n a ly s is ............... 261
8. 2
F u tu r e d e v e lo p m e n ts w ith in th e d is c ip lin e o f g eo g ra p h y ...........
264
8. 3
F u tu r e d e v e lo p m e n ts of d e c is io n m a k in g in r e s p o n s e to
d e v e lo p m e n ts in g e o g ra p h ic in fo rm a tio n s y s t e m s and
s p a ti a l a n a ly s is ...........................................................................................
267
8 .4
C o n c e p tu a l s e q u e n c e of e v e n ts b e tw e e n d a ta g a th e r in g an d
p o lic y d e c is io n m a k in g w ith in g o v e rn m e n t.......................................
269
8 .5
I n te r a c tio n s b e tw e e n d a ta c o lle c tio n , s p a ti a l d a ta h a n d lin g ,
m e n ta l an d f o r m a l s p a tia l a n a ly s is , a n d d e c is io n m a k in g ,
o v e r tim e . ......................................................................... ............................. 280
11
LIST O F T A B L E S
T a b le
T itle
Page
3. 1
S u m m a ry of r e s u l t s of d is ta n c e e s ti m a t io n an d
m e a s u r e m e n t.......................................................................................
74
3. 2
S u m m a ry of r e s u l t s of a r e a m e a s u r e m e n t t e s t ....................
76
5. 1
N u m b e r o f d a ta p o in ts r e q u i r e d to d e fin e a s e r i e s o f
i r r e g u l a r p o ly g o n s b y c h a in -e n c o d in g b o u n d a r ie s and
by s k e le to n m e th o d . ..................................................................
142
5. 2
P IO S : c o m p u te r ti m e r e q u i r e d to p r o c e s s an a v e ra g e
m a p f r o m d ig itiz a tio n to M a s te r F i l e f o r m a t.................................
149
5. 3
CGIS t e s t : s u m m a r y a n d tim e a n d c o s t a n a ly s is ...........................
162
5 .4
CG IS and. m a n u a l e q u iv a le n t ti m e s f o r h a n d lin g d a ta a t
v a r i o u s d e n s it ie s ...........................................................................................
164
5 .5
C G IS t e s t : t o t a l e la p s e d ti m e a n d c o s t r e q u i r e d to
c r e a t e d a t a b a n k .....................................................................................
165
5. 6
C G IS t e s t : r e t r i e v a l c o s t s ........................................................................
167
12
C H A P T E R 1 - IN TRO DU CTIO N
T h e o b je c tiv e s of th e th e s i s a r e to e x a m in e new d e v e lo p m e n ts in te c h n iq u e s
f o r h a n d lin g s p a ti a l d a ta , an d to c o n s id e r th e im p lic a tio n s o f t h e i r u s e o n th e
m e th o d o lo g ic a l a s p e c t s of g e o g ra p h y a n d on d e c is io n m a k in g in g o v e rn m e n t.
D a ta h a n d lin g f it s w ith in a l a r g e r f r a m e w o r k of d a ta g a th e r in g , d a ta a n a ly s is ,
a n d d e c is io n m a k in g .
C o n c e p tu a lly , th e in t e r a c t io n s a m o n g th e e le m e n ts in
th i s f r a m e w o r k a r e e x p r e s s e d in th e fo llo w in g d ia g r a m (F ig . 1. 1).
DATA
G A T H E R IN G
F ig . 1. 1.
DATA
H ANDLING
DATA A NA LYSIS M ODELS
(M E N T A L AND FO R M A L)
D ECISION -M A K IN G
PRO CESS
R e la tio n s h ip s b e tw e e n d a ta g a th e r in g , d a ta h a n d lin g , d a ta
a n a ly s is , an d d e c is io n m a k in g .
T h e s te p s n e c e s s a r y to a r r i v e a t d e c is io n s b a s e d o n o b s e r v e d p h e n o m e n a
a r e s u g g e s te d b y th e s m a l l b o x e s in th e d ia g r a m .
F o r th e p u r p o s e s o f
th i s d is c u s s io n it is a s s u m e d th a t p h e n o m e n a a r e o b s e r v e d , m e a s u r e d in
s o m e s u ita b le u n it(s) a n d d e s c r ib e d on th e b a s i s of th e s e m e a s u r e m e n t s .
W hen th e p h e n o m e n a h a v e b e e n d e s c r ib e d , a n a tte m p t c a n b e m a d e to
e x p la in t h e i r p r o p e r t ie s , s u c h a s t h e i r s p a t i a l d is tr ib u tio n .
I f th e y c a n b e
e x p la in e d , f u tu re c h a n g e s in th e v a r i a b le s c a n b e s u g g e s te d a n d d e c is io n s
c a n b e m a d e on th e b a s is o f th e p r e d ic te d o u tc o m e .
T h e s e s te p s c a n b e g ro u p e d in to s o m e w h a t m o r e f a m i l i a r c a te g o r ie s .
D a ta
g a th e r in g e n c o m p a s s e s th e v a r io u s te c h n iq u e s o f c e n s u s , s u r v e y , a d m in i­
s t r a t i v e r e c o r d k e e p in g , an d s o f o r th .
m a n ip u la tio n , an d d is p la y of d a ta .
D a ta h a n d lin g c o m p r is e s th e s to r a g e ,
D a ta a n a ly s is in v o lv e s f it tin g th e d a ta to
s o m e f o r m of m o d e l, e i th e r m e n ta lly in tu itiv e o r m o r e r i g o r o u s a n d f o r m a l,
th a t a llo w s th e p h e n o m e n a to b e u n d e rs to o d a n d , w ith g r e a t e r o r l e s s e r
d e g r e e s of a c c u r a c y , p re d ic te d .
D e c is io n -m a k in g p r o c e s s e s , w h e th e r
a c a d e m ic , p r a g m a tic , in d iv id u a l, in s titu tio n a l, o r p o li tic a l, c a n th e n r e s u l t .
13
It c a n b e s e e n th a t d a ta h a n d lin g i s a li m it e d p a r t of th is p r o c e s s .
It i s a n
e s s e n t i a l a n d i n t e g r a l p a r t o f th e s e r i e s b u t it d o e s n o t e n c o m p a s s d a ta
g a th e r in g , th e d e s ig n an d u s e of te c h n iq u e s f o r d a ta a n a ly s is , o r th e
d e c is io n - m a k in g p r o c e s s .
T h is th e s i s w ill c o n c e n tr a te o n th e h an d lin g of
s p a t i a l d a ta , b u t w ill r e l a t e th e h a n d lin g te c h n iq u e s to th e c h a r a c t e r i s t i c s
a n d v o lu m e s o f a v a ila b le d a ta a n d to th e s u b s e q u e n t n e e d s o f v a r io u s ty p e s
o f d a ta u s e a n d d e c is io n m a k in g .
D a ta h a n d lin g i t s e l f i s a n e x tr e m e ly la r g e f ie ld .
T o lim it th e s c o p e o f th e
t h e s i s , a tte n tio n w ill b e f o c u s s e d on te c h n iq u e s f o r h a n d lin g th e m a p p ed an d
r e l a t e d lo c a ti o n - s p e c if ic d a ta g a th e r e d b y g o v e rn m e n t a g e n c ie s .
T he.
s p e c i a l te c h n iq u e s f o r h a n d lin g d a ta f r o m p ic tu r e s (p ic tu r e p ro c e s s in g ) w ill
b e ig n o re d .
S im ila r ly , o n ly g o v e rn m e n t d e c is io n m a k in g w ill b e e x a m in e d .
A lth o u g h no d i r e c t e x a m in a tio n w ill b e m a d e o f th e p r iv a te a n d c o m m e r c ia l
s e c t o r s , o r o f th e o v e rw h e lm in g m a jo r ity of d a ta w h ic h is n o t o f a
lo c a ti o n - s p e c if ic ty p e , a n e x te n s iv e s u b je c t n e v e r t h e le s s r e m a in s .
M apped d a ta a n d r e l a t e d lo c a tio n - s p e c if ic d a ta h a v e p ro b a b ly b e e n g a th e r e d
an d h a n d le d s in c e a t l e a s t 2000 B. C .
O f n e c e s s i ty , m a n u a l c a rto g r a p h ic
te c h n iq u e s w e r e e m p lo y e d to c r e a te an d r e a d m a p s , an d s u c h te c h n iq u e s
a r e s t i l l th e m o s t w id e ly u s e d in th e w o rld to d a y .
M anual te c h n iq u e s h av e
s o m e a d v a n ta g e s , b u t th e y a ls o h a v e s ig n ific a n t d is a d v a n ta g e s .
A lthough
m a p s c a n b e a n e ffic ie n t w ay to s t o r e an d d is p la y d a ta c o n c e rn in g th e e a r t h 's
s u r f a c e , t h e r e a r e tw o b a s ic lim ita tio n s to t h e i r u s e .
T h e f i r s t i s th a t
t h e r e a r e p h y s ic a l li m it s on th e a m o u n t of d e s c r i p tiv e d a ta th a t c a n b e
s t o r e d a n d d is p la y e d on a n y m a p .
T o r e d u c e s u c h d a ta to a s e n s ib le g ra p h ic
f o r m , th e y m u s t b e c l a s s i f ie d an d g e n e ra liz e d , w h ic h to o o fte n c a u s e s a
lo s s o f d e t a il d u r in g th e t r a n s i tio n f r o m a l e s s to a m o re g e n e ra liz e d f o r m
of d a ta r e c o r d .
T h e s e c o n d lim ita tio n i s th a t in fo rm a tio n in a m a p f o r m a t,
a s w e know i t , h a s to b e r e t r i e v e d v is u a lly a n d m a n u a lly .
M e a s u re m e n t is
la b o r io u s , a n d q u a n tita tiv e c o m p a ris o n s a r e slow a n d e x p e n siv e .
A ny la r g e
c o lle c tio n of c a r t o g r a p h ic m a t e r i a l p r e s e n t s a fo r m id a b le t a s k of r e a d in g
an d a n a ly s is to o b ta in e v e n th e s im p l e s t u n d e rs ta n d in g of th e in f o rm a tio n it
c o n ta in s .
T h e te c h n iq u e s a n d e f f o r t in v o lv ed in th e m a n u a l h a n d lin g of m a p p ed d a ta
w ill b e e x a m in e d in d e ta il in C h a p te r 3.
T h e s u b se q u e n t c h a p te r s o f th e
14
th e s i s w ill c o n s id e r th e te c h n iq u e s th a t h a v e b e e n d e v e lo p e d in th e p a s t 15
y e a rs
(s in c e th e a d v e n t of th e e l e c tr o n ic c o m p u te r a m e n a b le in th e h an d lin g
of m a p p e d d a ta ).
B o th m a n u a l a n d c o m p u te r - a id e d te c h n iq u e s w ill b e
b ro u g h t to g e th e r a n d r e v ie w e d i n C h a p te r 6, s o th a t th e c u r r e n t o v e r a l l
c a p a b ility f o r h a n d lin g s p a t i a l d a ta m a y b e u n d e rs to o d .
T h is c a p a b ility
w ill th e n b e v ie w e d in C h a p te r s 7 a n d 8 in t e r m s of th e n e e d to h a n d le d a ta f o r
s p a ti a l a n a ly s is a n d d e c is io n m a k in g i n g o v e rn m e n t.
R E V IE W O F L IT E R A T U R E
I t i s c l e a r th a t th e t h e s i s d r a w s f r o m , an d i s c o n c e rn e d w ith , th e r e l a ti o n ­
s h ip s b e tw e e n c a rto g r a p h y , c o m p u tin g , in f o rm a tio n s y s t e m d e s ig n ,
g e o g r a p h ic a l e x p la n a tio n , f o r m a l s p a t i a l a n a ly s is , a n d to s o m e e x te n t
p o li tic a l s c ie n c e .
E a c h of t h e s e f ie ld s h a s a n e x te n s iv e l i t e r a t u r e b u t, a s
m a y b e e x p e c te d , w o rk i n th e m te n d s to fo c u s on m a t t e r s c e n tr a l to e a c h
d is c ip lin e r a t h e r th a n e x p lo r in g t h e i r i n t e r r e la tio n s h ip s .
E v e n t e x ts th a t
a tte m p t to e n c o m p a s s th e s c o p e o f t h e i r d is c ip lin e s a r e w e a k in th i s r e s p e c t .
T h e c l a s s i c a l t e x ts in c a rto g r a p h y , s u c h a s th e w o r k of R o b in so n o r
M o nkhouse an d W ilk in s o n , 1 a r e c o n c e r n e d m a in ly w ith th e "h o w " o f
p ro d u c in g m a p s a n d d ia g r a m s r a t h e r th a n th e "w h y ".
T he o v e ra ll lite ra tu re
o n c o m p u tin g is v a s t, b u t t h a t s p e c if ic a lly c o n c e r n e d w ith h a n d lin g s p a tia l
d a ta h a s b e e n s p a r s e .
(It w ill b e m o r e fu lly e x a m in e d below a n d in th e b o d y
of th e t h e s i s . ) T h e c o n c e p ts o f in fo rm a tio n s y s t e m d e s ig n a r e g e n e r a lly
a p p lic a b le to a l l d a ta , b u t t h e s y s t e m s u s e d a s e x a m p le s 2 h a v e c o n c e n tr a te d
o n th e n e e d s o f b u s in e s s m a n a g e m e n t, i n d u s tr i a l c o n tro l, e c o n o m ic p la n n in g ,
m i lit a r y s y s t e m s , a n d s o f o r th .
T h e s e v e r a l e x c e lle n t r e v ie w s o f f o r m a l
s p a ti a l a n a ly s is a n d g e o g ra p h ic a l e x p la n a tio n 3 do n o t c o v e r d a ta h a n d lin g
te c h n iq u e s in a n y d e p th .
T h e e x te n s iv e l i t e r a t u r e of p o li tic a l s c ie n c e ,
e v e n th a t d ir e c tl y c o n c e rn e d w ith d e c is io n m a k in g in g o v e rn m e n t,4 d o e s
n o t o fte n e x p lo r e th e s u p p ly a n d h a n d lin g of d a ta o n w h ich d e c is io n s a r e
based.
E v e n s tu d ie s s p e c if ic a lly c o n c e rn e d w ith g o v e rn m e n t m a n a g e m e n t
of th e e n v iro n m e n t5 m a k e o n ly li m it e d r e f e r e n c e to th e in h e r e n t t a s k of
h a n d lin g s p a ti a l d a ta .
It w o u ld b e w ro n g , h o w e v e r , t o s u g g e s t th a t th e p r o b le m s o f h a n d lin g
1. R o b in s o n 1969, M on k h o u se a n d W ilk in so n 1970. 2, M cD onough 1963,
C le la n d a n d K in g 1969, D odd 1969, B u rc h a n d S t r a t e r 1974. 3. C h o rle y
a n d H a g g e tt 1967, C o le a n d K ing 1968, B e r r y a n d M a rb le 1968, H a rv e y 1969,
R u s h to n e t a l. 1971. 4 . W a rd 1962, P o r t e r 1965, B r a y 1970. 5. M acN eill
1971.
15
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1. C op p o ck 1962, C o ppock a n d J o h n so n 1962, K ao 1963. 2. T o b l e r 1965.
3. D a c e y a n d M a rb le 1965. 4. D u e k e r 1966. 5 . P f a ltz 1967a. 6 . H â g e r s tr a n d
l 96 7 a . 7. B a lc h in a n d C o le m a n 1967. 8 . B e r tin 1970. 9. H a g g e tt 1969.
10. A u m en 1970. 11. F in k e ls te in 1970. 1 2 . B o y le 1970a. 13. A p p el e t a l . 1968.
16
t u b e s f o r d a ta in p u t a n d e d itin g , a n d P e t r i e 1 p r e s e n te d a n o v e rv ie w o f
c a rto g r a p h ic p lo ttin g d e v ic e s f o r a u to m a tic m a p p in g .
D u e k e r2 h a s
p u b lis h e d th e c l e a r e s t a n d m o s t s tr a i g h tf o r w a r d re v ie w o f th e m e th o d s of.
c o d in g g e o g r a p h ic a l p a t te r n s , th o u g h o th e r w o r k e r s 3 h av e p ro v id e d a l t e r n a tiv e s c h e m e s .
W illia m s 4 p r o d u c e d a v a lu a b le b ib lio g ra p h y o f w o r k o n
d a ta s t r u c t u r e s an d l a t e r s p e c i f ic a l ly re v ie w e d th o s e of u s e in c o m p u te r
g r a p h ic s y s t e m s .
T e c h n iq u e s f o r s p e c if ic m a n ip u la tio n s of s p a tia l d a ta in n u m e r ic a l f o r m
h a v e b e e n d e v e lo p e d b y m a n y w o r k e r s .
B o eh m 5 c o m p a re d v a r io u s t e c h -
n iq u e s o f s u r f a c e s a m p lin g a n d c o n c lu d e d th a t t h e r e i s no o p tim a l te c h n iq u e .
T h e t a s k of d ra w in g c o n to u rs h a s r e c e iv e d a g r e a t d e a l o f a tte n tio n ;
p r o b a b ly th e b e s t d is c u s s io n s a r e th e e a r l y one of B e n g tss o n a n d No r d b e c k 6
an d th a t in c lu d e d in th e w o r k o f H a rb a u g h a n d M e r r ia m .7
S p ecific c o n to u r in g
p r o g r a m s h a v e b e e n d e v e lo p e d b y n u m e ro u s w o r k e r s ,8 an d te c h n iq u e s o f
tr e n d s u r f a c e a n a ly s is r e c e iv e d e a r l y a tte n tio n f r o m g e o lo g is ts , n o ta b ly
K ru m b e in . 9 C h o r le y an d H a g g e tt, 10 H a rb a u g h an d M e r r ia m , 11 and
C a s s e tt i a n d S em p le12
h a v e r e v ie w e d th e w o rk of o th e r s .
T h e c o m p u te r -
a id e d m a n ip u la tio n of m a p p r o je c ti o n s h a s b e e n a c o n tin u in g i n t e r e s t o f
T o b le r 13
an d K ao .14
M ap g e n e ra liz a tio n w a s d is c u s s e d b y T o b l e r 15 a n d
K o e m a n an d v a n d e r W e id en , 16 a m o n g o th e r s .
T h is s a m p le of p u b lic a tio n s c o n f ir m s th a t a c o n s id e ra b le a m o u n t o f w o r k
h a s b e e n u n d e rta k e n on s p e c if ic a s p e c t s o f s p a ti a l d a ta h a n d lin g .
T a r r a n t 17
h a s p ro v id e d a p a r t i a l l i s t o f th e c o m p u te r p r o g r a m s a v a ila b le i n
th e g e o g ra p h y d e p a rtm e n ts of u n i v e r s i tie s , a n d P e u c k e r 18 h a s co m p ile d a.
b ib lio g r a p h y o n c o m p u te r c a rto g r a p h y .
L i t e r a t u r e d e a lin g e x p lic itly w ith g e o g ra p h ic in fo rm a tio n s y s t e m s i s l e s s
r e a d i l y a v a ila b le in e s ta b lis h e d jo u r n a ls .
It i s m a in ly to b e fo u n d in th e
f o r m o f g o v e rn m e n t p u b lic a tio n s , c o n fe re n c e p ro c e e d in g s , s y s t e m - r e la te d
m a n u a ls , o r m im e o g ra p h e d r e p o r t s .
V a rio u s c a te g o r ie s of ge o g ra p h ic
1. P e t r i e 1966. 2. D u e k e r 1972. 3. F r e e m a n 1961, P f a ltz a n d R o sen feld 1967 ,
J a r v i s 1971. 4 . W illia m s , R . 1 9 6 8 , 1971. 5. B o eh m 1967. 6. B e n g ts s o n and
N o rd b e c k 1964. 7. H a rb a u g h a n d M e r r ia m 1967. 8. M u r r a y 1968, D ay h o ff
1963, H eb in 1969,
T o b le r 1970,
H o lro y d an d B h a tta c h a y y a 1970 .
9. K ru m b e in 1959, 1966. 10. C h o rle y an d H ag g ett 1965. 11. H a rb a u g h a n d
M e r r ia m 1967. 12. C a s s e tt i a n d S e m p le 1968. 13. T o b le r 1962. 1 4 . K ao 1963.
15. T o b le r 1966. 16. K o e m a n a n d v an d e r W eiden 1970 . 17. T a r r a n t 1968 and
s u b s e q u e n t e d itio n s . 18. F e u c k e r 1972.
17
in fo rm a tio n s y s t e m s w ill b e d e s c r ib e d in th e b o d y o f th i s t h e s i s , w ith
s p e c if ic e x a m p le s .
A b ib lio g ra p h y of th e l i t e r a t u r e is p ro v id e d .
C O N T R IB U T IO N AND C O N T EX T O F TH ESIS
T h e c o n tr ib u tio n m a d e b y th is th e s i s i s to p ro v id e a c o h e re n t e x a m in a tio n
o f th e to o ls now a v a ila b le to lin k th e p r o c e s s e s of s p a tia l d a ta g a th e r in g an d
d e c is io n m a k in g .
M an u al a n d c o m p u te r - a id e d te c h n iq u e s f o r h an d lin g
s p a ti a l d a ta a r e v ie w e d n o t in t e r m s of t h e i r a b ility to p ro d u c e m a p s , b u t
in t h e i r b r o a d e r r o le of s to r in g , m a n ip u la tin g , a n d d is p la y in g d a ta f o r
d e c is io n -m a k in g p u r p o s e s .
P a r t i c u l a r a tte n tio n i s p a id to th e u ti lit y o f th e
r e c e n tly d e v e lo p e d n o n - g ra p h ic f o r m s of d a ta s to r a g e a s a r e p o s it o r y f o r
s p a t i a l d a ta .
T h e im p lic a tio n s of th e u s e of th e new to o ls f o r f o r m a l s p a ti a l
a n a ly s is a n d g o v e r n m e n t d e c is io n m a k in g a r e d is c u s s e d an d g u id e lin e s f o r
th e fu tu r e d e v e lo p m e n t of te c h n iq u e s f o r h a n d lin g s p a tia l'.d a ta a r e p u t
fo rw a rd .
T h e to o ls f o r h a n d lin g s p a ti a l d a ta m u s t of c o u r s e b e th o u g h t of i n th e
c o n te x t of th e in te n d e d u s e of th e d a ta .
f o r th e m a r e n o t in d e p e n d e n t.
T h e s u p p ly o f d a ta an d th e d e m a n d
In g e n e ra l, d a ta a r e o b ta in e d in r e s p o n s e
t o a v a r i e ty of in s titu tio n a l n e e d s , w h e th e r h i s t o r i c a l , c u r r e n t , a n tic ip a te d ,
r e a l , o r il lu s o r y .
T h is in flu e n c e of th e s o u r c e a g e n c ie s i s v e r y c l e a r
w h e n o n e lo o k s a t th e s u p p lie s of m a p p e d a n d r e l a t e d lo c a tio n - s p e c if ic d a ta .
A v a ila b le d a t a r e f l e c t th e in s titu tio n a l r e q u i r e m e n t s w ith in a p a r t i c u l a r
c o u n try , w h ic h in tu r n r e f l e c t t h e i r d iff e re n t n e e d s an d s t a t e s o f d e v e lo p m e n t.
A lthough th i s s itu a tio n m a y m e a n th a t d a ta a r e c o lle c te d f o r o n e
p u r p o s e o n ly a n d ca n n o t b e t r a n s f e r r e d to o th e r u s e s , it d o e s g e n e r a te d a ta
th a t a t l e a s t h a v e s o m e u s e .
D a ta h a v e no v a lu e e x c e p t in th e c o n te x t of
t h e i r u s e , a n d in th e p a s t th e y h a v e n o t b e e n g e n e ra lly c o lle c te d f o r t h e i r
ow n s a k e . 1 T h e to o ls f o r h a n d lin g d a ta a l s o h a v e n o t b e e n d e v e lo p e d f o r
t h e i r ow n s a k e , b u t r a t h e r h a v e g ro w n p r a g m a tic a lly out o f in s titu tio n a l
need.
T h e in flu e n c e of t h e i r in s titu tio n a l o r ig in i s p a r t ic u l a r ly p e r v a s iv e
in th e c u r r e n t e a r l y s ta g e of d e v e lo p m e n t of c o m p u te r- a id e d te c h n iq u e s
f o r h a n d lin g s p a t i a l d a ta ; e a c h o f th e c a te g o r ie s of te c h n iq u e to b e e x a m in e d
in l a t e r c h a p te r s i s r e l a t e d to s p e c if ic ty p e s of in s titu tio n a l a c tiv ity .
The
te c h n iq u e s a r e n o t n e c e s s a r i l y a p p lic a b le in e v e r y in s titu tio n a n d e v e r y
c o u n try , an d no u n iv e r s a l s y s t e m f o r h a n d lin g m a p p e d d a ta e x i s t s a t th e
1. H o w e v e r, w e m a y b e a c q u irin g s u c h an o v e rw h e lm in g a b ility to g a th e r
d a ta th a t t h e r e i s d a n g e r of u n d ire c te d a c c u m u la tio n in th e f u tu r e .
18
m o m e n t o r i s lik e ly to b e c r e a te d in th e n e a r fu tu r e .
T h e d e v e lo p m e n t of d a ta h a n d lin g m e th o d s , th e n , h a s g ro w n f r o m th e
in s ti tu ti o n a l n e e d to h a n d le d a ta ; c o n se q u e n tly , t h e i r u s e f u ln e s s a n d a p p lic a b ility in e a c h c o u n try m u s t b e ju d g e d w ith in th a t c o n te x t.
T H E S IS STR U C T U R E
T h e t h e s i s s t a r t s w ith a b r i e f e x a m in a tio n of th e c h a r a c t e r i s t i c s an d
a v a ila b ility of s p a ti a l d a ta , p r o c e e d s w ith an e x a m in a tio n o f m a n u a l an d
c o m p u te r - a id e d s p a t i a l d a ta h a n d lin g te c h n iq u e s , a n d en d s w ith th e d i s c u s s io n of th e r e l a ti o n s h i p s b e tw e e n g e o g ra p h ic in f o rm a tio n s y s te m s ,
f o r m a l s p a ti a l a n a ly s is , a n d d e c is io n m a k in g in g o v e rn m e n t.
T h e ty p e an d am o u n t of s p a ti a l d a ta th a t e x i s t o b v io u s ly a ffe c t th e n e e d f o r
d a ta h a n d lin g c a p a b ility .
L o c a tio n -s p e c if ic d a ta th e m s e lv e s r e s u l t f r o m
th e d e s c r i p tio n of e n t iti e s o r c o n d itio n s w ith in s p a c e , an d th e n a t u r e of
th e d e s c r i p tio n d e p e n d s on th e c o n c e p t of s p a c e a n d th e la n g u a g e e m p lo y e d .
T h e r a n g e of th e s e p o s s i b ili tie s i s b r ie f ly e x a m in e d in th e f i r s t p a r t o f
C h a p te r 2.
T h e in flu e n c e of th e s to r a g e m e d iu m o n th e d a ta f o r m a t i s
c o n s id e r e d .
D e s p ite th e w id e r a n g e of c o n c e p tu a lly p o s s ib le a p p r o a c h e s
to s p a ti a l d e s c r ip tio n , th e o v e rw h e lm in g a m o u n t of e x is tin g lo c a tio n - s p e c if ic
d a ta a s s u m e s E u c lid e a n s p a c e a n d i s s to r e d o n d o c u m e n ts in e i th e r g r a p h ic
o r s y m b o lic d a ta f o r m a ts .
T h e m o s t c o m m o n ly u s e d ty p e s o f lo c a tio n
id e n tif i e r a r e id e n tifie d a n d d is c u s s e d .
T h e n e x t s te p i s a n e x a m in a tio n o f v a r ia tio n s in th e su p p ly of s u c h s p a ti a l
d a ta .
A n in v e n to ry of s p a ti a l d a ta s u p p lie s in v a r i o u s c o u n tr ie s i s o u ts id e
th e s c o p e of th e t h e s i s , b u t th e f a c t o r s th a t in flu e n c e d a ta g a th e r in g a n d
th e r a n g e of v a r ia tio n w ith in e a c h f a c t o r a r e d is c u s s e d in th e s e c o n d p a r t
of C h a p te r 2.
I t is s e e n th a t e a c h d a ta s e t w ith in e a c h c o u n try ( o r e v e n in
d if f e re n t p a r t s of a c o u n try ) m a y e x h ib it c h a r a c t e r i s t i c s th a t r e q u i r e
d iffe re n t s u b s e q u e n t h a n d lin g .
T h e o v e r a l l su p p ly a n d a v a ila b ility o f s p a ti a l
d a t a m a y v a r y s u b s ta n tia lly f r o m one c o u n try to a n o th e r .
C o n se q u e n tly ,
th e u s e f u ln e s s of v a r io u s a p p ro a c h e s to d a ta h a n d lin g v a r i e s b e tw e e n
c o u n tr ie s an d th e a p p r o p r ia te m ix tu r e of te c h n iq u e s f o r an y o n e c o u n try
d e p e n d s on th e d a ta a v a ila b le w ith in it.
T h e s e o b s e r v a tio n s a r e m a d e a t
th e o u ts e t of th e t h e s i s s o th a t e l e c tr o n ic c o m p u te r m e th o d s f o r s p a ti a l
19
d a ta h a n d lin g c a n b e e x a m in e d s u b s e q u e n tly i n a c l e a r e r p e r s p e c tiv e .
T h is
p r e l im i n a r y d is c u s s io n d o e s , h o w e v e r, m a k e it c l e a r th a t c a p a b ilitie s f o r
d a ta g a th e r in g a r e r a p i d ly e x p a n d in g .
T h e in c r e a s e d p e r c e iv e d n e e d f o r
s p a ti a l d a ta a n d th e g ro w th of th e te c h n o lo g ie s b a s i c to d a ta a c q u is itio n
s u g g e s t th a t th e p r e s e n t r a p i d i n c r e a s e in v o lu m e of s p a ti a l d a ta w ill
c o n tin u e .
T h is g ro w th , w h e th e r o r n o t it i s w e ll d ir e c te d , w ill g e n e ra te
in c r e a s in g q u a n titie s of s p a ti a l d a ta w h ich w ill n e e d to b e h a n d le d .
M an u al te c h n iq u e s f o r h a n d lin g m a p p e d d a ta a n d o th e r lo c a tio n - s p e c if ic
d a ta f o r m th e b e n c h m a r k s of t r a d iti o n a l c a p a b ility a g a in s t w h ich m a c h in e
m e th o d s m u s t b e ju d g e d ; th e y a r e e x a m in e d in C h a p te r 3.
T h e e ffic ie n c y
o f th e m a p a s a s o u r c e of d a ta f r o m w h ich u s e f u l in fo r m a tio n m u s t b e
e x t r a c te d a n d th e te c h n iq u e s f o r e x t r a c ti n g i t a r e d is c u s s e d .
M an u al
p r o c e s s e s a r e th u s re v ie w e d in th e c o n te x t o f d a t a h a n d lin g r a t h e r th a n
s im p ly a s t r a d iti o n a l c a rto g r a p h ic p r a c t ic e .
M ap s a r e r e g a r d e d a s g ro u p s
o f r e c o r d s , o r " f i l e s " , in w h ic h s p a ti a l d a ta a r e s to r e d .
T h e arra n g e m e n t
of d a ta on a m a p i s c o n s id e re d a s a " file s t r u c t u r e " , a n d m a n u a l h an d lin g
te c h n iq u e s a r e th o s e u s e d to m a n ip u la te , g ro u p , a n d e x t r a c t d a ta f r o m th e
file s .
A v e r y w id e r a n g e of s p a ti a l d a ta h a n d lin g t a s k s ca n b e a c c o m p lis h e d
m a n u a lly , c o n s tr a in e d m a in ly b y th e tim e a n d e f f o r t n e e d e d to p e r f o r m
th e m ; th e d is c u s s io n in C h a p te r 3 f o c u s s e s o n t h e i r e ffic ie n c y .
In g e n e ra l,
t a s k s th a t r e l y o n m a n u a l m o to r p r o c e s s e s , s u c h a s d a ta t r a n s f e r b y tr a c in g ,
o r m a n u a l m e a s u r e m e n t , a r e s e e n to b e slo w .
o n m e n ta l d a ta p r o c e s s in g a r e f a s t .
T e c h n iq u e s th a t r e l y m a in ly
T e c h n iq u e s th a t r e l y on c o m b in a tio n s
o f th e s e p r o c e s s e s i n c r e a s e in e ffic ie n c y a s th e p ro p o r tio n o f m e n ta l d a ta
p r o c e s s in g b e c o m e s g r e a t e r , u n til th e m a x im u m r a t e a t w h ic h b i t s of
in fo rm a tio n c a n b e t r a n s m itt e d to th e b r a i n (h u m a n s e n s o r y c h a n n e l ca p acity )
is re a c h e d .
M o re s p e c if ic a lly , m a p s c a n b e e c o n o m ic a lly h a n d le d b y
m a n u a l te c h n iq u e s if th e p r o c e s s e s in v o lv e r e a d i n g a n d m a n ip u la tio n o r
g ro u p in g , o r b o th , o f d a ta w r itt e n d ir e c tl y on th e m a p .
G ra p h ic s o u r c e d a ta
ca n n o t b e h a n d le d s o e ffic ie n tly , h o w e v e r, w h en th e d a ta to b e e x tr a c te d b y
m a n u a l m e a s u r e m e n t a n d c o m p a r is o n a r e in h e r e n t in t h e i r f il e s tr u c t u r e .
I n c r e a s i n g d a ta v o lu m e ra p id ly m a k e s i t u n e c o n o m ic a l to m a n ip u la te and
20
e x t r a c t e v e n th e d a ta a c tu a ll y w r itt e n i n th e f i l e .
A ls o , im p r o v e m e n ts in
th e fle x ib ility of a g r a p h ic f il e u s u a lly im p ly c r e a tio n of m u ltip le g r a p h ic
r e c o r d s , an d h e n c e i n c r e a s e th e b i t s of d a ta to b e h a n d le d ; g ra p h ic s o u r c e
m a t e r i a l ca n b e s a id to im p o s e a n in h e r e n t in f le x ib ility o n f ile s t r u c t u r e s ,
an d is n o t v e r y e ffic ie n t a s a s o u r c e of l a r g e v o lu m e s of s p a t i a l d a ta .
T h e e x a m in a tio n o f e l e c tr o n i c c o m p u te r - a id e d te c h n iq u e s f o r h a n d lin g
s p a ti a l d a ta th u s p r o c e e d s f r o m th e o b s e r v a tio n th a t th e v o lu m e of. s p a ti a l
d a ta a v a ila b le in th e w o r ld i s r a p i d ly in c r e a s in g a n d th a t g ra p h ic s to r a g e
m e d ia an d m a n u a l te c h n iq u e s a r e in a d e q u a te to h a n d le l a r g e v o lu m e s o f d a ta .
T h e s to r a g e o f s p a ti a l d a t a b y e l e c tr o n i c c o m p u te r s h a s tw o in h e r e n t
p h y s ic a l a d v a n ta g e s .
T h e f i r s t i s th e r e l a t i v e l y c o m p a c t n a tu r e o f th e
s to r a g e c o m p a re d w ith c o n v e n tio n a l g ra p h ic s to r a g e .
T h e s e c o n d ad v a n ta g e
i s m o r e c r u c i a l, s in c e i t a d d s a new d im e n s io n to th e f i r s t ; t h i s i s th e
a b i lit y to u s e e s ta b lis h e d c o m p u tin g m a c h in e s to r e a d , s t o r e , a n d m a n ip u la te
n o n - g ra p h ic s t o r e s of s p a t i a l d a ta .
In a d d itio n , s u c h s t o r e s o f d a t a a r e
r e l a ti v e ly e a s y to a u g m e n t, e d i t, a n d c o r r e c t w ith o u t re n e w in g th e e n t i r e
s to r a g e .
F o r a l l c o m p u te r s i n g e n e r a l u s e in 1 9 7 3 -7 4 , h o w e v e r , m a p p e d
d a ta a n d r e l a t e d lo c a ti o n - s p e c if ic d a t a m u s t b e a v a ila b le i n a c o d e d ,
m a c h in e - r e a d a b le , n o n - g r a p h ic f o r m of s to r a g e .
A f te r th e r a n g e of c o d e d , n o n - g ra p h ic s p a t i a l d a t a f o r m a ts a n d th e b a s ic
a t tr ib u t e s of f il e s t r u c t u r e s h a v e b e e n o u tlin e d i n C h a p te r 4 , g e n e r a l f o r m a t r e l a t e d c a te g o r ie s of c o m p u te r - a id e d te c h n iq u e s a r e e x a m in e d , a n d t h e i r
c h a r a c t e r i s t i c s a r e i l l u s t r a t e d w ith s p e c if ic e x a m p le s in C h a p te r s 4: a n d 5.
T h e C a n a d a G e o g ra p h ic I n f o rm a tio n S y ste m , w h o se d e v e lo p m e n t w a s
in i tia te d a n d d ir e c te d b y th e a u t h o r , i s e x a m in e d w ith in t h i s c o n te x t.
C o m p u te r-a id e d te c h n iq u e s a r e c o m p a re d w ith m a n u a l o n e s , a n d t r e n d s in
th e d e v e lo p m e n t of d ig itiz a tio n te c h n iq u e s , i n t e r a c t iv e d a ta - b a s e m a n ip u la tio n , o u tp u t d e v ic e s , a n d m ul t i f o r m a t s y s t e m s a r e a ls o e x a m in e d s o th a t
t h e i r p o te n tia l c o n tr ib u tio n to s p a t i a l d a ta h a n d lin g c a n b e c o n s id e r e d .
F r o m th i s e x a m in a tio n c o m e s th e view th a t it i s g e n e r a lly c h e a p e r a n d
q u ic k e r t o u s e a c o m p u te r t o m a n ip u la te s p a ti a l d a t a th a n to h a n d le n u m e ro u s,
m a p s m a n u a lly , p a r t i c u l a r l y w h e n m e a s u r e m e n ts h a v e t o b e m a d e a n d w h en
c o m p a r is o n s b e tw e e n d if f e re n t m a p s a r e n e e d e d .
T h e r e a r e d if f ic u ltie s .
21
h o w e v e r.
T h e m a in s h o r tc o m in g of th e c o m p u te r - a id e d a p p ro a c h is th a t
c u r r e n t ly it is u n e c o n o m ic a l to t r a n s f o r m th e d a ta f r o m m a p s in to a
m a c h in e - r e a d a b le f o r m a t, a n d th i s im p o s e s c o n s tr a in ts on th e am o u n t o f
d a ta s to r e d in th e c o m p u te r a n d th e w ay th e y a r e s to r e d .
th e c h a lle n g e a n d p r o s p e c t o f th e new te c h n iq u e s .
T h e r e in li e s
If it i s p o s s ib le to
re m o v e o r r e d u c e th e d iffic u ltie s of m a k in g m a p s re a d a b le b y m a c h in e ,
an d t h e r e is e v e r y e v id e n c e th a t i t i s , th e n t h e r e is a good p r o s p e c t of
u s in g c o m p u te rs to r e a d an d m a n ip u la te m a p s .
P a r a d o x ic a lly , th e f u ll c a p a b ili tie s o f m o d e rn c o m p u te r s a r e s ig n if ic a n tly
u n d e r - u t ili z e d b y e v e n th e m o s t a d v a n c e d of th e e x is tin g s y s te m s f o r
h a n d lin g s p a ti a l d a ta .
T h is i s p a r t l y b e c a u s e s y s t e m s a r e c u r r e n t ly a t a n
e a r l y s ta g e of d e v e lo p m e n t, b u t p a r t l y a ls o b e c a u s e of a la c k o f an y
c l e a r l y s ta t e d r e q u i r e m e n t s to m a n ip u la te th e d a ta in w a y s th a t u s e
m o d e rn s t a t i s t i c a l o r m o d e l- b a s e d a p p ro a c h e s a n d s o ta k e a d v a n tag e o f
th e c o m p u te r s ’ c a p a b ilitie s .
T h e r e a r e s e v e r a l r e a s o n s f o r th i s d e fic ie n c y ,
s o m e s te m m in g f r o m th e ty p e of in s titu tio n s th a t h a v e f o s te r e d th e g ro w th
o f th e new te c h n iq u e s , a n d s o m e a r i s i n g f r o m th e p r e s e n t m e th o d s of
d e c is io n m a k in g a n d th e tr a in in g of d e c is io n m a k e r s .
S e v e ra l o f th e c o m -
p u te r - a id e d te c h n iq u e s , in f a c t , ca n b e r e c o g n iz e d a s c o n c e p tu a l
e x te n s io n s o f t r a d iti o n a l m a n u a l c a rto g r a p h y , d e s ig n e d to p r e s e n t s p a tia l
d a ta in a f o r m th a t h u m a n b e in g s c a n c o m p re h e n d b y v is u a l e x a m in a tio n .
O nly r e c e n t d e v e lo p m e n ts in c o m p u te r - a id e d te c h n iq u e s h av e t r i e d to
e x te n d h u m a n a n a ly tic a l c a p a b ili tie s b y s y s t e m a tic a lly c o m p a rin g an d
m a n ip u la tin g th e s p a ti a l d a ta w ith in th e c o m p u te r an d p r e s e n tin g th e r e s u l t s
to th e u s e r .
T h e s e th o u g h ts a r e s y n th e s iz e d in C h a p te r 6.
T h e v a r io u s s e ts o f te c h -
n iq u e s a n a ly s e d in th e p re v io u s c h a p te r s a r e b ro u g h t to g e th e r in a n a tte m p t
to s e e w h a t p r o g r e s s i s b e in g m a d e , an d a te n ta tiv e f ra m e w o r k i s p ro v id e d
w ith in w h ich b o th m a n u a l a n d c o m p u te r - a id e d s y s t e m s a r e lo c a te d s o th a t
th e i r r e l a ti v e c a p a b ilitie s f o r h a n d lin g s p a ti a l d a ta c a n b e u n d e rs to o d .
The
c o n trib u tio n of th e v a r io u s te c h n iq u e s to th e o v e r a l l a b ility to h a n d le s p a ti a l
d a ta i s th u s s u m m a r iz e d .
T h e c a te g o r ie s of d iffe re n t c a p a b ilitie s e m e r g e ,
t h e i r in s titu tio n a l b a c k g ro u n d s a r e m a d e c l e a r , an d s e v e r a l im p o r ta n t
22
q u e s tio n s a r e r a i s e d ab o u t th e w ay in w h ic h th e te c h n iq u e s a r e d e v e lo p in g ,
t h e i r u tility , a n d th e lik e ly fu tu re p r o g r e s s of g e o g ra p h ic in fo rm a tio n
s y ste m s .
T h e s e p ro b le m s r e l a te on th e one h a n d to g e o g r a p h ic a l th e o r y
a n d f o r m a l s p a ti a l a n a ly s is , and on th e o th e r to d e c is io n - m a k in g p r o c e s s e s .
C h a p te r s 7 a n d 8 a tte m p t to ta c k le s o m e of th e s e i s s u e s , w h ich a r e o b v io u s ly
c o m p le x a n d n o t a m e n a b le to e a s y s o lu tio n .
In C h a p te r 7, th e c o n tr ib u tio n s
o f th e c a te g o r ie s of e x is tin g s y s t e m s to f o r m a l s p a t i a l a n a ly s is a n d
g o v e rn m e n ta l d e c is io n m a k in g a r e e x a m in e d .
In t e r m s of f o r m a l s p a ti a l a n a ly s is , th e new te c h n iq u e s h a v e n o t c o n tr ib u te d
to th e o r y c r e a tio n , b u t h a v e th e p o te n tia l to s p e e d th e c o u r s e of th e o r y
t e s t in g an d allow new a v e n u e s to b e e x p lo re d m o r e r a p id ly .
S p e c ific a lly ,
t h e y m a y h e lp b y m a k in g a v a ila b le in fo rm a tio n th a t w ould :
1)
allo w c u r r e n t m o d e ls to b e te s t e d o v e r a w id e r a r e a , o r f o r m o r e
d is a g g r e g a te d p o p u la tio n s ;
2)
allo w th e d e v e lo p m e n t of new m o d e ls (o fte n d e riv e d f r o m o ld th e o ry )
th a t m a y in c o r p o r a te v a r i a b le s n o t b e f o re a v a ila b le in q u a n tita tiv e
f o r m ; th i s m a y , in tu r n , le a d to c o m p le te ly new ty p e s o f t h e o r e ti c a l
d e v e lo p m e n t;
3)
a s a s p e c i a l c a s e o f (2) ab o v e , p ro v id e d a t a o n c h a n g e s th a t o c c u r at
p a r t i c u l a r p la c e s , an d th e in t e r r e la tio n s h ip b e tw e e n c h a n g e s at
p la c e s (th a t i s , th e in te r a c tio n b e tw e e n a ttr ib u te an d tim e o v e r s p a c e );
t h i s m a y h e lp to d ev e lo p a n d im p ro v e d y n a m ic m o d e ls o f in n o v a tio n ,
d iffu s io n , th e la g g e d e f fe c ts o f e c o n o m ic a n d s o c ia l c h a n g e , and so
f o r th .
In t e r m s o f g o v e rn m e n t d e c is io n m a k in g , e x is tin g g e o g ra p h ic in f o r m a tio n
s y s t e m s a r e s e e n to m a k e t h e ir m a in c o n trib u tio n to th e m e n ta l d e c is io n
p r o c e s s a t m a n a g e m e n t an d p o lic y le v e ls of d e c is io n m a k in g .
In g e n e ra l, it i s a p p a re n t th a t alth o u g h th e p r o c e s s e s of s p a ti a l d a ta h an d lin g ,
f o r m a l s p a ti a l a n a ly s is , an d d e c is io n m ak in g a r e in te rd e p e n d e n t, t h e r e is
a s u b s ta n tiv e la c k of in te r a c tio n b e tw e e n th e m .
A lth o u g h th e d e v e lo p m e n t
of c o m p u te r - a id e d s y s te m s s o f a r h a s g ro w n o u t o f a c o m b in a tio n of
p r a g m a tic n e e d a n d in te lle c tu a l c u r io s ity a s m u c h a s f r o m a n y n a r r o w ly
d e fin e d p r o g r e s s i o n of te c h n ic a l ev o lu tio n , t h e r e h a v e b e e n few lin k a g e s
23
b e tw e e n th e d e v e lo p m e n t of s u c h s y s t e m s an d th e p r o c e s s e s o f f o r m a l
s p a ti a l a n a ly s is o r g o v e rn m e n t d e c is io n m aking.
T h e f u tu r e d e v e lo p m e n t of te c h n iq u e s f o r h an d lin g s p a tia l d a ta i s c o n s id e r e d in C h a p te r 8, f i r s t f r o m th e p o in t of view of th e te c h n ic a l a s p e c ts
of th e s y s t e m s th e m s e lv e s , an d se c o n d ly , in t e r m s of t h e i r r e la tio n s h ip
w ith th e d is c ip lin e of g e o g ra p h y a n d th e p r o c e s s o f d e c is io n m a k in g in
g o v e rn m e n t.
T h e g u id e lin e s p ro p o s e d f o r d e v e lo p m e n t of te c h n iq u e s a r e r e l a ti v e ly
s tr a ig h tf o r w a r d .
Im p ro v e m e n t in th e te c h n iq u e s f o r tr a n s f o r m a tio n f r o m
g r a p h ic to n o n -g ra p h ic f o r m a t i s im p o r ta n t if d ig ita l c o m p u te r s a r e to b e
u sed.
T h e s t o r e s o f a v a ila b le s p a ti a l d a ta w ill in c r e a s e i f e x is tin g n o n -
g r a p h ic d a ta s e t s a r e m a d e m o r e c o m p a tib le a n d q u a n tita tiv e d a ta
g a th e r in g p r o c e s s e s a r e u s e d m o r e f re q u e n tly .
D ev elo p m en t o f th e
c a p a b ility f o r m a n ip u la tio n w ill s t e m fr o m b e t te r u s e of in te r a c tiv e
(m a n -m a c h in e ) c o m p u te r c a p a b ili tie s , b e t te r s t a t i s t i c a l u n d e rs ta n d in g of
th e m a n ip u la tio n p r o c e s s e s th e m s e lv e s , th e g ro w th of m u ltim o d a l s y s t e m s ,
an d th e d e s ig n o f f ile s t r u c t u r e s b a s e d on f u r th e r d ev e lo p m en t o f la n g u a g e s
u s e d f o r o r d e r i n g s p a ti a ll y d is tr i b u te d d ata.
T h e d e v e lo p m e n t of g e o g ra p h ic in f o rm a tio n s y s t e m s w ith in th e c o n te x t of
f o r m a l s p a ti a l a n a ly s is a n d g o v e rn m e n t d e c is io n m a k in g is l e s s s t r a i g h t fo rw ard .
I t i s not p o s s ib le to f o r e c a s t th e im p a c t of g e o g ra p h ic in f o r m a -
tio n s y s t e m s on th e d is c ip lin e of g e o g ra p h y , b u t i t i s r e a s o n a b le to ex p e c t
s o m e m u tu a l s h if ts of e m p h a s is in b o th fo r m a l s p a tia l m o d e ls a n d in th e
s y s t e m s th e m s e lv e s a s t h e i r d e v e lo p m e n t c o n tin u e s .
T o g e th e r w ith
e x a m p le s of r e l a t e d d e v e lo p m e n ts in o th e r d is c ip lin e s , th e e v id e n c e
s u g g e s ts th e fo llo w in g d e v e lo p m e n ts :
1)
B e t te r u s e o f th e a p r i o r i know ledge of in d iv id u a l s itu a tio n s w ill
le a d to th e n e e d to u s e d is a g g r e g a te d d a ta s e ts .
I t a ls o im p lie s th e
th e o r e ti c a l d e v e lo p m e n t o f lin k a g e s b e tw e e n m ic r o d a ta a n d m a c r o d a ta ,
if u n d e r s ta n d in g of th e l a r g e r s o c io -e n v iro n m e n ta l m e c h a n is m s i s to
b e g ain ed .
2)
T h e s e d e v e lo p m e n ts in t u r n r e s t on a d v a n c e s in g e o g ra p h ic in fo rm a tio n
s y s t e m s , b o th to m a k e b e t t e r u s e of a v a ila b le s t o r e s o f in fo rm a tio n
24
a n d to h a n d le th e a t tr ib u t e - s p a c e - t im e in te r a c tio n s am o n g d a ta .
T h is
w ill d e p e n d on s u b s ta n tia l im p ro v e m e n ts in th e file s t r u c t u r e s of
g e o g ra p h ic in fo r m a tio n s y s te m s .
3)
T h e d e v e lo p m e n t of m o r e e ff ic ie n t file s t r u c t u r e s w ill d ep e n d to a
c o n s id e r a b le e x te n t on th e t h e o r e ti c a l d e v e lo p m e n t o f m u ltid im e n s io n a l
la n g u a g e s .
T h is ty p e o f m u tu a l d e v e lo p m e n t of f o r m a l s p a tia l a n a ly s is a n d g e o g ra p h ic
in fo r m a tio n s y s t e m s w ill h av e c o n s id e r a b le im p a c t on th e a v a ila b ility o f
r e l e v a n t in fo r m a tio n to p ro v id e u n d e r s ta n d in g of s p a ti a l d is tr ib u tio n an d
in t e r a c t io n s .
C o n s id e r a tio n of th e f u tu r e d e v e lo p m e n t of g e o g ra p h ic in f o r m a tio n s y s t e m s
f o r g o v e r n m e n t d e c is io n -m a k in g p u r p o s e s s im i la r l y le a d s to th e c o n c lu s io n
th a t b o th t h e o r e t i c a l and p r a g m a tic a d v a n c e s m u s t r e l y o n e x p lo r a tio n a n d
re c o g n itio n of th e in te r d e p e n d e n c e of th e s u b je c ts .
T h e im p lie d in c r e a s e s
in c o m m u n ic a tio n w ill n o t b e a c h ie v e d w ith o u t e ff o rt.
T h e d e v e lo p m e n t
of in t e r - i n s t i t u t i o n a l d a ta lin k a g e s w ill in a l l p r o b a b ility h a v e c o n s id e r a b le
im p a c t on th e su p p ly of a v a ila b le s p a ti a l d a ta an d h e n c e th e ty p e o f d e c is io n
m a k in g th a t c a n b e n e fit f r o m im p r o v e d h a n d lin g te c h n iq u e s a n d im p ro v e d
f o r m a l s p a ti a l a n a ly s is .
T h e la c k o f f o r m a l tr a in in g o f p r e s e n t - d a y
d e c is io n m a k e r s in q u a n tita tiv e m e th o d s u n d o u b te d ly a f f e c ts th e p e r c e iv e d
n e e d f o r a n d u n d e rs ta n d in g of f o r m a l s p a tia l a n a ly s is , a n d h e n c e th e d e s ig n
a n d u s e of g e o g ra p h ic in fo rm a tio n s y s t e m s to p ro v id e d a ta f o r b o th f o r m a l
a n d m e n ta l m o d e ls .
A s a n i n t e r i m m e a s u r e , i t i s s u g g e s te d th a t th o s e
c o n c e rn e d w ith th e d e v e lo p m e n t of f o r m a l s p a tia l a n a ly s is te c h n iq u e s , an d
in p a r t i c u l a r w ith th e d e s ig n of g e o g ra p h ic in fo rm a tio n s y s t e m s , m u s t
u n d e r s ta n d th a t it i s n e c e s s a r y to e n c o u ra g e u s e r s to b e c o m e c o m p e te n t
i n q u a n tita tiv e m e th o d s of p ro b le m s o lv in g a s w e ll a s to b u ild in fo r m a tio n
s y s t e m s a n d f o r m a l a n a ly tic a l c a p a b ilitie s .
I t i s r e c o g n iz e d th a t in c r e a s e d c a p a b ility f o r g a th e r in g d a ta m a y le a d in
th e f o r e s e e a b le f u tu r e to th e c o lle c tio n of la r g e v o lu m e s o f d a ta , w h ich
w e m a y o r m a y n o t b e a b le to h a n d le an d w h ich w e m a y o r m a y n o t n ee d .
I t i s a p p a re n t th a t in c r e a s e d fe e d b a c k f r o m p o lic y le v e ls o f g o v e rn m e n t i s
n e e d e d to id e n tify w h ich s p a tia l d a ta sh o u ld p ro fita b ly b e c o lle c te d , an d to
p ro v id e th e c r i t e r i a f o r d e lim ita tio n .
A s f a r a s is know n, n o o r g a n iz a tio n a l
25
m e c h a n is m s a r e in p la c e to im p ro v e th a t fe e d b a c k .
I t i s s u g g e s te d th a t
th e f i r s t im p r o v e m e n ts in fe e d b a c k m a y c o m e f r o m th e u s e o f g e o g ra p h ic
in f o rm a tio n s y s t e m s .
O n ly w h en d a ta a r e a c tu a lly r e a d a n d u s e d in m e n ta l
o r f o r m a l m o d e ls , an d i t c a n b e show n th a t c h a n g e s of c o n te n t o r f o r m a t
a r e n e c e s s a r y o r th a t o th e r d a ta m ig h t be p r o f ita b ly c o lle c te d w ith th e
s a m e e x p e n d itu re of fu n d s , c a n p e r s u a s io n b e b ro u g h t to b e a r o n tr a d iti o n a l
d a ta g a th e r in g a g e n c ie s to a m e n d t h e i r s ta n d a r d f o r m s o f o p e ra tio n .
T h e s e c o n d le v e l of im p ro v e m e n t in fe e d b a c k w ill c o m e w h en im p ro v e d
s p a ti a l m o d e ls a r e in t e g r a t e d in to th e d e c is io n -m a k in g p r o c e s s a n d c a n b e
u s e d to s p e c if y d a ta r e q u i r e m e n t s .
m a k in g p r o c e s s a s w e know it to d a y .
T h is im p lie s a ch a n g e in th e d e c is io n A s u b s t a n ti a l d e g r e e o f in te g r a tio n
o f f o r m a l te c h n iq u e s in th e d e c is io n -m a k in g p r o c e s s w o u ld b e n e e d e d
b e f o r e t h e i r d a ta n e e d s w ould r e p r e s e n t a s tr o n g a r g u m e n t f o r c h a n g in g
e s ta b lis h e d d a ta g a th e r in g p r a c tic e .
T h e p o s s i b ili ty of s u c h c h a n g e s in th e d e c is io n -m a k in g p r o c e s s is d is c u s s e d
in C h a p te r 8 a n d p o s s ib le o r g a n iz a tio n a l s t r u c t u r e s a r e p o s tu la te d .
In
a d d itio n , th e r e c e n t d e v e lo p m e n t of in te r a c tio n s b e tw e e n d a ta c o lle c tio n ,
s p a ti a l d a ta h a n d lin g , m e n ta l a n d f o r m a l s p a ti a l a n a ly s is , an d d e c is io n
m a k in g a r e re v ie w e d a n d th e tim in g of f u tu r e c h a n g e s i s a s u b je c t of
s p e c u la tio n .
I t i s s e e n th a t th e d e v e lo p m e n t of g e o g r a p h ic in fo rm a tio n
s y s t e m s ca n n o t s e n s ib ly p ro c e e d f u r t h e r in is o la tio n , b u t m u s t b e u n d e r ta k e n a s a n in t e g r a l p a r t of a v e r y l a r g e s t r u c t u r e of d a t a g a th e r in g , d a ta
a n a ly s is , a n d d e c is io n m a k in g .
26
C H A P T E R 2 - C H A R A C TE R IST IC S AND A V A ILA B ILITY O F
LO CA TIO N -S P E C IF IC DATA
T h e o b je c tiv e s of th i s c h a p te r a r e tw ofold: f i r s t , to o u tlin e th e c h a r a c t e r i s t i c s of lo c a ti o n - s p e c if ic d a ta th a t a ffe c t t h e i r s u b s e q u e n t h a n d lin g , b y
e i th e r m a n u a l o r c o m p u te r - a id e d p r o c e d u r e s ; a n d s e c o n d ly , t o g iv e an
u n d e rs ta n d in g of th e f a c t o r s th a t a f fe c t th e g e n e ra tio n of s u c h d a ta an d
d e te r m in e t h e i r s u p p ly a n d a v a ila b ility .
T h e d a ta of c o n c e rn in th i s t h e s i s a r e th o s e d e r iv e d b y o b s e r v a tio n an d
m e a s u r e m e n t of c e r t a i n a s p e c t s of th e e a r t h 's s u r f a c e , th e e n v iro n m e n t,
r e s o u r c e s , p o p u la tio n , a n d r e l a t e d a t tr ib u t e s w ith in th e liv in g s p a c e of
m a n k in d .1
T h e s e d a t a a r e o fte n d is p la y e d o n m a p s p ro d u c e d b y g o v e r n -
m e n t a g e n c ie s .
T o li m i t th e s c o p e of th e d is c u s s io n , th e lo c a tio n - s p e c if ic
d a ta r e f e r r e d to w ill b e th o s e g e n e ra lly g a th e r e d b y g o v e rn m e n t a g e n c ie s .
C H A R A C T E R IST IC S O F L O C A T IO N -S P E C IF IC DATA
T h e f i r s t t a s k i s to d e fin e th e m e a n in g of " lo c a tio n - s p e c if ic " d a ta .
The
in fo r m a tio n c o n te n t o f a s in g le d a tu m , o r " d a ta e le m e n t" , c a n b e r e g a r d e d
a s h a v in g t h r e e p o te n tia l c o m p o n e n ts .
T h e s e a r e " s u b s ta n c e " in fo rm a tio n ,
" lo c a tio n a l" in f o rm a tio n , a n d " te m p o r a l" in fo rm a tio n .
S u b sta n c e in f o r m a -
tio n d e s c r i b e s th e a t tr ib u t e s , c h a r a c t e r i s t i c s , v a r i a b le s , v a lu e s , f e a t u r e s ,
a n d s i m i l a r q u a litie s o f th e d a tu m ; th e r a n g e f o r a n y o n e d a tu m m a y
o b v io u s ly b e m u ltid im e n s io n a l.
L o c a tio n a l in f o rm a tio n d e s c r i b e s th e
p o s itio n o f th e d a tu m in s p a c e r e l a ti v e to o th e r d a ta .
T e m p o r a l in f o r m a -
tio n d e s c r i b e s th e in s ta n t o r p e r io d in tim e f o r w h ic h th e d a tu m i s v a lid .
F ig u r e s c o n c e rn in g th e a c c u r a c y o f a n y of th e t h r e e p o te n tia l co m p o n en ts
m a y b e a d d e d a s s u p p le m e n ta ry in fo rm a tio n .
O ne o r m o re of th e in fo r m a tio n c o m p o n e n ts i s p r e s e n t in e a c h d a tu m .
If
th e lo c a tio n a l in f o rm a tio n i s p r e s e n t , th e d a tu m i s t e r m e d " lo c a tio n s p e c i f ic " .
A lo c a tio n - s p e c if ic d a ta s e t i s a c o lle c tio n of d a ta th a t a r e
in d iv id u a lly o r c o lle c tiv e ly a tta c h e d to lo c a tio n ; " s p a ti a l d a ta " i s a t e r m
u s e d sy n o n y m o u s ly w ith lo c a tio n - s p e c if ic d a ta .
S p a tia l d a ta s y s t e m s o r
1. No r ig o r o u s d e fin itio n of th e liv in g s p a c e of m a n k in d w ill b e a tte m p te d .
In g e n e ra l t e r m s i t w ill b e ta k e n a s th e s p a c e c o n ta in e d o n th e e a r t h 's
s h e ll b e tw e e n th e M oho d is c o n tin u ity in th e c r u s t a n d th e u p p e r li m it of
th e a t m o s p h e r e , in th a t m a n a s a n u n s u p p o rte d o r g a n is m m u s t s t i l l (1974)
r e m a in w ith in th o s e b o u n d s. T h e u p p e r l i m it , in p a r t i c u l a r , h o w e v e r,
c a n b e tr a n s c e n d e d b y m a n k in d w ith th e a i d o f v e h ic le s .
27
g e o g ra p h ic in f o rm a tio n s y s t e m s a r e s e t s of te c h n iq u e s th a t allow th e
lo c a tio n a l in fo rm a tio n o f th e d a ta to b e m a n ip u la te d in c o n c e r t w ith t h e i r
re m a in in g v a lu e .
T o p ro v id e lo c a tio n a l in fo rm a tio n it is n e c e s s a r y to h a v e a c o n c e p t o f
s p a c e a n d a la n g u a g e in w h ich t o e x p r e s s a d e s c r ip tio n .
A f u ll d is c u s s io n of th e c o n c e p ts of s p a c e , th e s t r u c t u r e a n d c a p a b ilitie s
o f a v a ila b le la n g u a g e s , a n d th e m e th o d s o r " m o d e ls " of m e a s u r e m e n t
a n d c la s s i f ic a t io n i s o u ts id e th e l i m it s o f th i s t h e s i s .
T h e c o m m e n ts th a t
fo llo w m e r e ly o u tlin e th e a s s u m p tio n s th a t u n d e r lie c u r r e n t p r a c t i c e , s o
th a t th e c h a r a c t e r i s t i c s of e x is tin g s p a ti a l d a ta ca n b e b e t t e r u n d e r s to o d
a n d th e s c o p e f o r f u tu r e d e v e lo p m e n ts c a n b e v is u a liz e d .
C o n c e p ts of S pace
C o n c e p ts of s p a c e m a k e a d is tin c tio n b e tw e e n p h y s ic a l a n d p e r c e p tu a l tr u t h .
P h y s i c a l t r u t h r e s t s u p o n e x p e rim e n t.
W ith in th e li m it s o f c u r r e n t e x p e r i -
m e n ts , m o s t w r i t e r s a g r e e (though th i s i s s t i l l a n o p e n q u estio n ) th a t
p h y s ic a l s p a c e f o r p r a c t i c a l p u r p o s e s i s E u c lid e a n in s tr u c t u r e ; s p a c e c a n
g e n e ra lly b e th o u g h t of a s h a v in g th r e e d im e n s io n s .
c o n s id e r e d to b e a fo u r th d im e n s io n .
T im e m a y th u s b e
(W h ere e x tr e m e e x t r a t e r r e s t r i a l
d is ta n c e s a r e c o n c e r n e d , m a tte r , o r f ie ld s , m a y b e c o n s id e r e d a s a f if th
d im e n s io n , th o u g h th i s h a s no p r a c t i c a l a p p lic a tio n in s p e c ify in g th e
r e l a t i v e lo c a tio n of d a ta r e l a t e d to th e e a r t h ’s s u r f a c e . )
P e r c e p t u a l s p a c e , 1 on th e o th e r h a n d , m a y h a v e n u m e ro u s d im e n s io n s .
R e la tio n s h ip s b e tw e e n o b je c ts o n th e e a r t h ’s s u r f a c e , th e e x te n t o f a r e a l
u n it s , a n d s o f o r th , c a n b e m e a s u r e d o n ly i n f o u r d im e n s io n s o r l e s s , i n
p r a c t i c a l te r m s of p h y s ic a l s p a c e .
m ay
H o w e v e r, in p e r c e p tu a l t e r m s , th e y
in v o lv e m a n y " d im e n s io n s " , s u c h a s c o s t, s a tis f a c tio n , u ti lit y , o p p o r -
tu n ity , s o c ia l in te r a c tio n , an d s o on.
A n in t e r e s ti n g il lu s tr a t io n o f th i s
c o n c e p t i s I s a r d 's 2 p e r c e p tu a l view of " p o litic a l tim e " a s a p a th t r a c e d in
a c o n c e p tu a l th r e e - d im e n s i o n a l fr a m e w o r k of c a le n d a r ti m e , ti m e t o th e
n e x t e le c tio n , a n d li f e s p a n tim e of th e p o litic ia n .
S uch a m u ltid im e n s io n a l
p e r c e p tu a l view of tim e m a y b e r e q u i r e d to u n d e r s ta n d g o v e rn m e n t
d e c is io n m a k in g a n d to d e s c r i b e i t a d e q u a te ly .
S im ila rly , a view o f
d is ta n c e s , e x te n t of a r e a l u n its , an d s o f o r th w ith in a m u ltid im e n s io n a l
1. T h e r e p r e s e n t a ti o n of s p a c e b y m e a n s o f im a g in e r y c o n c e p ts . 2. I s a r d 1970.
28
p e r c e p tu a l view o f s p a c e m a y b e n e c e s s a r y to u n d e r s ta n d th e d is tr ib u tio n s
a n d in t e r a c t io n s o f o b je c ts on th e e a r t h 's s u r f a c e .
T h e c o n c e p t of s p a c e
e m p lo y e d , a s w e ll a s th e e m p ir ic a l p r o p e r t ie s of th e c o n c e p ts b e in g
e x a m in e d , u n d e r lie th e c h o ic e of la n g u a g e u s e d .
S p a tia l L a n g u a g e s
I te m s th a t o c c u p y p o s itio n s in s p a c e ca n b e n a m e d .
T h e r e p la c e m e n t of
p r o p e r n a m e s b y th e t e r m s of s o m e c o o r d in a te s y s t e m a llo w s th e p o s itio n
o f th e it e m s t o b e m o re g e n e ra lly s ta te d .
T h e s e t s of r u le s g o v e rn in g th e
u s e of s u c h c o o r d in a te s y s t e m s c a n b e r e g a r d e d a s " s p a ti a l" la n g u a g e s .
T h e E u c lid e a n c o n c e p t of s p a c e u n d e r l ie s E u c lid e a n g e o m e tr y , w h ich h a s
d o m in a te d th e d e s c r ip tio n s of s p a c e f o r o v e r 2 ,0 0 0 y e a r s .
I ts s im p lic ity
i s i t s s tr e n g t h , a n d m a n y g e o g ra p h ic a l c o n c e p ts a r e c a s t in E u c lid e a n
t e r m s s im p ly to allo w u s e of th e a n a ly tic a l to o ls of E u c lid e a n g e o m e try .
In th e 17th c e n tu r y , co m p le x (E uclidean) g e o m e tr ic a l p r o b le m s w e r e s o lv e d
b y a l g e b r a ic m e a n s .
V e c to r an d te n s o r a l g e b r a s w e r e l a t e r d e v e lo p e d to
h a n d le tw o - a n d th r e e - d im e n s i o n a l g e o m e tr ic a l p r o b le m s .
G e o m e tr y c a n
s i m i l a r l y b e r e l a t e d to p r o b a b ility th e o ry , n u m b e r th e o r y , la tti c e th e o r y ,
an d s o on.
T h e s ig n ific a n c e of th e a lg e b r a ic a p p ro a c h i s th a t g e o m e tr ic
c o n c e p ts a n d th e o r e m s c a n b e e x te n d e d to t h r e e , f o u r , a n d u p to a n
in f in ite n u m b e r of d im e n s io n s .
T h e 19th c e n tu r y , h o w e v e r, saw th e
e m e r g e n c e of n o n -E u c lid e a n g e o m e tr i e s , w h ic h w e r e b a s e d on d if f e re n t
c o n c e p ts o f p h y s ic a l s p a c e .
H a rv e y 1 n o te s th a t:
"T h e h y p e r b o lic s p a c e of L o b a c h e v s k y a n d B o ly a i w a s th e s p a c e of
c o n s ta n t n e g a tiv e c u r v a t u r e , th e e llip tic s p a c e of R ie m a n n w a s th e
s p a c e of c o n s ta n t p o s itiv e c u r v a t u r e , a n d th e f la t s p a c e o f E u c lid
w a s th e s p a c e of z e r o c u r v a tu r e . E v e r y p e r c e p tu a l s h a p e f r o m a
f la t b o a r d to a H e n ry M o o re s ta tu e c o u ld b e g iv e n a c o o rd in a te
s y s t e m , w h ich w ould d efin e th e in t r i n s i c g e o m e tr y of th a t s h a p e . . .
s o g e n e r a l w a s th e th e o r y th a t R ie m a n n d e v is e d th a t i t co u ld b e
e x te n d e d to m o r e th a n t h r e e d im e n s io n s . "
G e o m e tr ie s th u s e x is t th a t allo w d is c u s s io n of n - d im e n s io n a l s p a c e .
At
th e e n d of th e 19th c e n tu ry , K le in 2 in p a r t ic u l a r d e v e lo p e d a new g e o m e tr y
fo u n d e d on th e to p o lo g ic a l c h a r a c t e r i s t i c s of o b je c ts .
T h is g e o m e tr y is
e s s e n t i a l l y n o n m e tr ic a l, an d c o n c e r n e d o n ly w ith th e c o n tin u o u s c o n n e c te d n e s s o f p o in ts on a f ig u r e .
A c o n s id e r a b le r a n g e of la n g u a g e s i s th u s a v a ila b le f o r s p a ti a l d e s c r ip tio n .
1. H a rv e y 1969.
2. K le in ( E n g l is h e d .) 1939.
29
f o r th e a s s ig n m e n t of lo c a tio n id e n tif i e r s to d a ta .
T o p o lo g y , f o r e x a m p le ,
i s d i r e c t l y a p p lic a b le to th e s tu d y of th e c o n n e c tio n s b e tw e e n s e ttle m e n ts
b y a s e t of tr a n s p o r t a ti o n lin k s .
C a lc u la tio n s r e l a ti n g to c u r v e d s p a c e ,
s u c h a s tr a n s f o r m a tio n s f r o m o n e m a p p r o je c tio n to a n o th e r , c a n e ffic ie n tly
m a k e u s e o f th e m o r e r e c e n tly d e v e lo p e d a n a ly tic a l g e o m e tr ie s .
The
c a lc u la tio n of a n g le s an d d is ta n c e s in n a v ig a tio n a l p r a c t ic e , on th e o th e r
h a n d , i s m u c h s im p l e r b y E u c lid e a n th a n s p h e r ic a l g e o m e try .
A lg e b ra s
p ro v id e c o n v e n ie n t w a y s of h a n d lin g c a lc u la tio n s in m u ltid im e n s io n a l sp ace..
T h e s p a ti a l la n g u a g e s , h o w e v e r, h a v e b e e n d e v e lo p e d in d is c ip lin e s o th e r
th a n g e o g ra p h y .
T h e ir a p p lic a tio n to g e o g ra p h ic a l p ro b le m s is g ro w in g ,
b u t r e p r e s e n t s a fu tu r e p o te n tia l r a t h e r th a n a w id e s p r e a d c u r r e n t p r a c t ic e .
T h is p a r t i c u l a r l y a p p lie s to th e g a th e r in g of s p a ti a l d a ta .
T h e s p a tia l
la n g u a g e of la titu d e a n d lo n g itu d e (o r lo c a l C a r t e s ia n c o o rd in a te s y s te m s ) ,
b a s e d o n E u c lid e a n s p a c e , i s u s e d f o r a lm o s t a l l m a p s an d lo c a tio n id e n tif ie r s
a v a ila b le to d a y .
E u c lid e a n g e o m e tr y i s th e to o l m o s t fre q u e n tly u s e d f o r
d e r iv in g m e a s u r e m e n ts a n d c o m p a ris o n s f r o m s u c h d a ta .
In s u b se q u e n t
c h a p te r s i t w ill b e s e e n th a t th e f ile s t r u c t u r e s of s p a ti a l d a ta s y s t e m s a r e
a l s o in flu e n c e d b y th i s t r a d iti o n r a t h e r th a n b y th e c o n c e p t o f p e r c e iv e d
s p a c e o r th e la n g u a g e s a m e n a b le to m u ltid im e n s io n a l c a lc u la tio n .
S p a tia l D e s c r ip tio n
D e s c r ip tio n o f it e m s m a y b e n o m in a l o r o rd in a l.
In n o m in a l d e s c r ip tio n
(b in a r y m e a s u r e m e n t) , th e o b je c t o r e v e n t i s g iv e n a p r o p e r n a m e (la b e l),
o r o n e r e l a ti n g to a s y s t e m of c la s s if ic a tio n .
T h e c o n n e c tio n b e tw e e n s u c h
a n a m e a n d a lo c a tio n id e n tif i e r m a y b e e s ta b lis h e d b y r e f e r e n c e to a
s e p a r a t e d e s c r ip tio n , b u t is n o t in h e r e n t in th e n a m e its e lf .
c r i p tio n im p lie s s o m e f o r m of m e a s u re m e n t.
O r d in a l d e s -
M e a s u re m e n t i s n o t d e s ir a b le
o r u n d e s ir a b le in its e lf ; it is m e r e ly u s e fu l o r n o t u s e fu l.
p r e s u p p o s e a c o n c e p t of s p a c e an d a s u ita b le la n g u a g e .
It d o e s , h o w e v e r,
T he s c a le s u sed fo r
m e a s u r e m e n t m a y b e s in g le ( s c a l a r m e a s u r e m e n t) , s u c h a s o r d in a l, in t e r v a l ,
o r r a t i o s c a l e s , w h ic h a s s u m e a s in g le , o n e - d im e n s io n a l, u n d e rly in g
c o n tin u u m ; o r m u ltid im e n s io n a l ( v e c to r, te n s o r , o r o th e r m e a s u r e m e n ts ) .
L o c a tio n id e n tif i e r s p r e s u p p o s e m u ltid im e n s io n a l m e a s u r e m e n t an d , f o r
E u c lid e a n c o n c e p ts , a s s u m e o rth o g o n a l a x e s th a t p o s s e s s th e s a m e s c a le
c h a ra c te ris tic s .
M e a s u re m e n t in p e r c e p tu a l s p a c e , h o w e v e r, m a y u s e
1. A n o ta b le e x c e p tio n i s th e d a ta g a th e re d b y th e E R T S s a te lli te s e n s in g
d e v ic e s . See C h a p te r 5, p. 178.
30
a x e s th a t a r e n o t o rth o g o n a l a n d m a y m ix a x e s th a t h a v e o r d in a l, i n t e r v a l ,
o r ra tio s c a le s .
T h e e m p ir ic a l p r o p e r t i e s o f th e o b je c ts o r e v e n ts b e in g d e s c r ib e d , a n d
th e n e e d f o r th e d e s c r ip tio n , o b v io u s ly h a v e im p a c t on th e c h a r a c t e r i s t i c s
o f th e d a ta (in c lu d in g th e lo c a tio n id e n tif ie r ) .
If o b je c ts o r e v e n ts a r e r e p r e s e n t e d a s a s e r i e s of s e p a r a t e p o in ts in s p a c e ,
i n ti m e , o r in s p a c e - t im e , th e y a r e th o u g h t of a s " d is c r e te " i t e m s .
If
th e y c a n b e r e p r e s e n t e d a s le n g th s ,1 a r e a s , o r v o lu m e s in s p a c e o r i n
s p a c e - t im e (m o v e m e n t), th e y m a y b e th o u g h t of a s " c o n tin u o u s " i t e m s . 2
B o th d i s c r e t e a n d co n tin u o u s o b je c ts o r e v e n ts m a y b e c o u n ta b le , f in ite
b u t u n c o u n ta b le ,3 o r in fin ite in n u m b e r.
O nly if th e y a r e c o u n ta b le b y
a v a ila b le te c h n iq u e s o f o b s e rv a tio n an d m e a s u re m e n t c a n a "co m p le te "
o b s e r v a tio n b e m a d e .
In a l l o th e r c a s e s , a n d e v e n in m a n y in s ta n c e s
w h e r e th e y a r e c o u n ta b le , a s a m p le i s ta k e n .
T h e w a y in w h ic h t h i s s a m p l e
i s ta k e n o b v io u s ly h a s im p a c t on th e u s e of th e d a ta .
A s a m p le m a y b e
d e s ig n e d to r e p r e s e n t co n tin u o u s d a ta b y d is c r e te d a ta , o r v ic e v e r s a .
S p a tia l D a ta F o r m a t
D a ta f o r m a t i s d e fin e d a s th e w ay in w h ich d a ta e le m e n ts a r e r e p r e s e n t e d
a n d s t o r e d in r e c o r d s .
G ro u p s of r e c o r d s a r e t e r m e d " f il e s " , a n d t h e
a r r a n g e m e n t of d a ta w ith in a file is th e " file s t r u c t u r e " .
R ec o rd s a r e
p h y s ic a l e n t iti e s a n d th e w ay in w h ich d a ta a r e s to r e d in th e m d e p e n d s
p a r t l y on th e la n g u a g e e m p lo y e d a n d p a r t ly o n th e c h a r a c t e r i s t i c s o f t h e
s to r a g e m e d iu m .
S to ra g e m e d ia m a y b e e s s e n ti a ll y o n e - d im e n s io n a l ( s u c h
a s r u l e r s , p ie c e s o f s t r i n g , s in g le - tr a c k m a g n e tic ta p e s ) , tw o - d im e n s io n a l
(d o c u m e n ts , p h o to g ra p h s , c o m p u te r c o r e s to r a g e ), o r t h r e e -d im e n s io n a l.
(g lo b e s , h a r d w a r e m o d e ls ,s te r e o p h o n ic g ra m o p h o n e r e c o r d s , h y d r o g r a p h ic
m o d e ls , h o lo g r a m s ,
4
e tc . ).
W ith in a n y s p a t i a l c o n c e p t, it i s p o s s ib le to e n v is a g e d i s c r e t e p a i n ts , c o n -
1. L e n g th s in o n e -d im e n s io n a l tim e a r e r e p r e s e n t e d b y a n u m b e r o f u n it s
a n d h e n c e a r e d i s c r e t e . P e r c e p t u a l tim e s u c h a s I s a r d 's " p o li tic a l tim e "
i s a le n g th th ro u g h a p e r c e p tu a l s p a c e . 2. C e r ta in e v e n ts m a y h a v e b o th
d i s c r e t e a n d c o n tin u o u s c o m p o n e n ts , i. e. , th o s e in v o lv in g in t e r m i tte n t
m o tio n . 3. F o r e x a m p le , in s e c t p o p u la tio n s of a c o u n try , s a n d g r a i n s o n
a b e a c h , e tc . 4. H o lo g ra m s a r e a s p e c i a l c a s e o f th r e e - d im e n s i o n a l
s to r a g e in th a t th e t h r e e - d im e n s io n a l d a ta a r e s t o r e d w ith o u t tr a n s f o r m a tio n ,
o n m o le c u le s w ith in a tw o -d im e n s io n a l m e d iu m b u t a r e e x t r a c te d , s e p a r a t e d ,
a n d re c o m b in e d to f o r m a th r e e - d im e n s io n a l h o lo g ra p h ic m o d e l u s in g
c o h e re n t lig h t.
31
tin u o u s l i n e s , a r e a s , a n d v o lu m e s (ite m s w h ich in th e m s e lv e s h av e n o
d im e n s io n , o n e d im e n s io n , tw o d im e n s io n s , o r t h r e e o r m o r e d im e n s io n s ).
T h e s e i t e m s m a y b e d e s c r ib e d in a v a r i e ty of s p a ti a l la n g u a g e s , e i th e r in
s y m b o lic f o r m , u s in g a lp h a n u m e ric a n d s p e c i a l s y m b o ls , o r in g r a p h ic f o r m
b y d ia g r a m s .
If th e la n g u a g e i s e x p r e s s e d in s y m b o lic f o r m , it ca n b e
r e c o r d e d on a n y o f th e s to r a g e m e d ia m e n tio n e d ab o v e.
If th e la n g u a g e is
e x p r e s s e d in g r a p h ic f o r m , e n titie s w ith d im e n s io n s th e s a m e a s o r l e s s
th a n th o s e in h e r e n t in th e c h o s e n s to r a g e m e d iu m c a n b e d e s c r ib e d w ith o u t
tr a n s f o r m a tio n a n d th e in f o rm a tio n r e d u c tio n th a t th e tr a n s f o r m a tio n m a y
in c u r .
If tw o - d im e n s io n a l d o c u m e n ts a r e u s e d a s a s to r a g e m e d iu m , th e c o n c e p t
o f E u c lide a n s p a c e i s a d o p te d , an d a g r a p h ic f o r m a t i s e m p lo y e d , o n ly
p o in ts , li n e s , a n d p la n e s u r f a c e s c a n b e a d e q u a te ly r e p r e s e n t e d (F ig . 2. 1).
W a rp e d p la n e s 1 a n d v o lu m e s m u s t b e t r a n s f o r m e d b e fo r e b e in g r e c o r d e d .
T h e s a m e m e d ia c o n s tr a in t a p p lie s w hen m u ltid im e n s io n a l s p a c e is
assum ed.
In
d e a lin g w ith fo u r - d im e n s io n a l s p a c e - t im e , f o r e x a m p le , a tw o -
d im e n s io n a l m e d iu m c a n a d e q u a te ly c o n ta in in fo rm a tio n o n li n e a r d is ta n c e x
ti m e (th a t i s , a g ra p h of v e lo c ity ) a s a s in g le r e c o r d .
H o w e v e r, s u r f a c e x
ti m e o r o th e r c o n s t r u c t s of t h r e e o r m o r e d im e n s io n s can n o t b e r e p r e s e n t e d
w ith o u t t r a n s f o r m a tio n .
S im ila r ly , th e g r a p h ic d e s c r ip tio n of th e in t e r a c t io n s b e tw e e n o b je c ts o r
e v e n ts , o r b o th , i s li m it e d b y th e d im e n s io n a l c h a r a c te r o f th e s to r a g e
m e d iu m .
S p e c if ic a lly , th e h ig h e s t n u m b e r of d im e n s io n s p o s s e s s e d b y an y
o n e e n tity in v o lv e d in th e in t e r a c t io n m u s t n o t e x c e e d th a t o f th e m e d iu m .
O n tw o - d im e n s io n a l s to r a g e , f o r e x a m p le , i t is p o s s ib le to r e c o r d p o in ts
i n a s e t of p o in ts (fo r e x a m p le , b r i c k b u ild in g s am o n g w ooden b u ild in g s ),
p o in ts o n li n e s ( r a ilw a y s ta tio n s ) , li n e s on li n e s (u npaved p a r t s o f a h ig h w ay ),
li n e s in a r e a s ( t r a i l s in a p a rk ), o r a r e a s i n a r e a s (is la n d s in a la k e ) , b u t
i t i s n ot p o s s ib le t o show th e lo c a tio n of p o in ts , li n e s , p la n e s , o r v o lu m e s
w ith in a v o lu m e w ith o u t tr a n s f o r m a tio n ( s u b m a rin e s in th e s e a , r o c k e t
t r a j e c t o r i e s , c o ld f r o n ts in a n a i r m a s s , o r c lo u d s in th e sk y ).
1. W a rp e d p la n e s (fo r e x a m p le , a n i r r e g u l a r to p o g ra p h ic s u rf a c e ) c a n b e
c o n s id e r e d to b e a f o r m of " e x te n d e d " tw o -d im e n s io n a l f e a tu r e . T h e y a r e
fr e q u e n tly r e c o r d e d on m a p s b y u s e of p o in t p a t te r n s , o r is o lin e s (w ithout
w h ic h i t w o u ld b e c o n s id e ra b ly m o re d iffic u lt to r e p r e s e n t v o lu m e s ). A
tr a n s f o r m a tio n h a s , h o w e v e r, o c c u r r e d f r o m th e w a rp e d p la n e to it s
r e p r e s e n t a ti o n b y p o in ts o r is o li n e s .
32
S P A T IA L DIM ENSIONS O F E N T IT IE S
T O B E RECORD ED
0
1
DIM ENSIONS
O F STO RAG E
M EDIA
2
GS
S
G
G =
S =
(G)=
=
G
S
2
S
G
G
3
G R O U PED R ECO RD S
1
3
4
5→
5+
E q u iv a le n t in E u c lid e a n g e o m e try
p o in t lin e surface s o lid
(a re a ) (vol.)
E q u iv a le n t in to p o lo g y
node
a r c re g io n 3 -D
(vertex) (edge) (face) fig .
G
G
S
S
S
S
S
S →
G
S
G
S
G
G
S
G
S
S
S →
S
S→
S
S→
i
S
G
S
S
(G)
S
G ra p h ic e x p r e s s io n of s p a ti a l la n g u a g e p o s s ib le
S y m b o lic e x p r e s s io n of s p a ti a l la n g u a g e p o s s ib le
L im ite d g r a p h ie e x p r e s s io n of s p a ti a l la n g u a g e p o s s ib le
O v e rw h e lm in g m a jo r it y of e x is tin g s p a ti a l d a ta r e c o r d s
F ig . 2. 1.
R e l a t i o n s h i p s b e tw e e n th e s p a ti a l d im e n s io n s of e n titie s
to b e r e c o r d e d , g r a p h ic a n d s y m b o lic r e c o r d s , and
th e c h o ic e of th e s to r a g e m e d ia .
D e s p ite th e li m it a ti o n s , h o w e v e r, th e o v e rw h e lm in g m a jo r ity o f e x is tin g
r e c o r d s a r e s to r e d on tw o -d im e n s io n a l d o c u m e n ts .
N e a r ly a l l s p a ti a l d a ta
a r e (in 1974) in i tia lly p o r tr a y e d o n m a p s , d ia g r a m s , o r p h o to g ra p h s.
The
p r o c e s s o f t r a n s f o r m in g m u ltid im e n s io n a l d a ta to a tw o - d im e n s io n a l g ra p h ic
f o r m a t u n d e r l ie s th e w h o le tr a d iti o n o f m a p p r o je c tio n s , c a rto g r a p h ic
s y m b o liz a tio n , a n d th e m o r e r e c e n t t r a n s f o r m a tio n s o f p e r c e p tu a l s p a c e to
g r a p h ic f o r m .
I t w a s m e n tio n e d a b o v e th a t a c o m p le te o b s e r v a tio n c a n b e m a d e o n ly w h e r e
o b je c ts o r e v e n ts a r e c o u n ta b le . F o r f in ite b u t u n c o u n ta b le , o r in fin ite ,
n u m b e r s of o b je c ts (an d f r e q u e n tly f o r o b je c ts w ith in co u n ta b le s e t s ) , a
s a m p le i s ta k e n .
T h e c o n s tr a in t of m e a s u r e m e n t on th e s a m p lin g te c h n iq u e
33
m a y b e th a t m u ltid im e n s io n a l o b je c ts a r e r e p r e s e n t e d b y d a ta w ith f e w e r
d im e n s io n s .
T h is is th e c a s e w hen p o in t d a ta a t w e a th e r s ta tio n s a r e u s e d
to s a m p le th e c o n tin u o u s v o lu m e of th e a tm o s p h e r e , d r i l l c o r e s a r e u s e d to
s a m p le th e in s id e of o r e b o d ie s , an d a e r i a l p h o to g ra p h s a r e u s e d to s a m p le
to p o g ra p h y .
A lth o u g h th e d a ta f r o m s u c h m e a s u r e m e n ts c a n b e r e c o r d e d
on a s to r a g e m e d iu m th a t d o es n o t a d e q u a te ly r e p r e s e n t th e e n tity b e in g
s a m p le d , a m e n ta l o r c a lc u la tiv e tr a n s f o r m a tio n i s r e q u i r e d to u n d e r s ta n d
th e e n tity f r o m th e r e c o r d e d d ata.
R e c o r d s i n g r a p h ic f o r m a t ca n b e g ro u p e d , in a n a tte m p t to o v e rc o m e th e
d im e n s io n a l c o n s tr a in t o f th e m e d iu m .
M any p ie c e s of o n e -d im e n s io n a l
s t r i n g c o u ld b e la id s id e b y s id e o n a ta b le to p an d a tw o - d im e n s io n a l m ap
c o u ld b e d ra w n a c r o s s th e m .
A p ie c e of s t r i n g c o u ld b e w ra p p e d a ro u n d a
d r u m a n d th e o u tlin e of a th r e e - d im e n s i o n a l f ig u r e co u ld b e tr a c e d u p o n it.
T w o -d im e n s io n a l d o c u m e n ts ca n b e s u p e r im p o s e d , e a c h r e p r e s e n t in g a
" s l i c e " th r o u g h a v o lu m e .
(T h is i s done d a ily w ith m e te o r o lo g ic a l c h a r t s
of v a r io u s le v e ls of th e a tm o s p h e re . ) T h r e e - d im e n s io n a l h a r d w a r e m o d e ls
c a n b e c a u s e d to m ove to r e p r e s e n t f o u r - d im e n s io n a l s p a c e - tim e .
The
a b i lit y w ith w h ic h s u c h " f ile s " c a n b e c o n s tr u c te d a n d h a n d le d i s c l e a r ly a
c o n s tr a in t of th e m e d ia .
R e c e n t d e v e lo p m e n ts in th e f ie ld h a v e le d to g r e a t e r p o s s i b ili tie s .
Tw o-
d im e n s io n a l p h o to g ra p h s ca n b e sh o w n in s e q u e n c e q u ic k ly en o u g h to a d d a
p e r c e p tu a l d im e n s io n of ti m e (c in e m a ).
S te re o s c o p ic p a i r s o f p h o to g ra p h s
c a n b e v ie w e d s im u lta n e o u s ly an d a p e r c e p tu a l t h r e e -d im e n s io n a l s u r f a c e
c a n b e o b s e r v e d a n d m e a s u r e d (p h o to g r a m m e tr y ) .
R e c o rd s fro m o n e-
d im e n s io n a l m a g n e tic ta p e ca n q u ic k ly g e n e ra te tw o -d im e n s io n a l g ra p h ic
a r r a y s , a n d if th e a r r a y s a r e p ro d u c e d in f a s t s e q u e n c e a p e r c e p tu a l tim e
d im e n s io n i s a d d e d (te le v is io n ).
If th e a r r a y s a r e w r itt e n on to tw o -
d im e n s io n a l c o m p u te r c o r e s to r a g e in r a p i d s e q u e n c e , a lim ite d t h r e e d im e n s io n a l r e p r e s e n t a ti o n of s p a c e i s g e n e ra te d in w h ich c a lc u la tio n s m a y
b e p erfo rm e d .
T h e fu tu r e d e v e lo p m e n t of c o m p u te rs w ith p a r a l le l p r o c e s s in g
c a p a b ility (m u ltip le tw o -d im e n s io n a l a r r a y s ) , o r h o lo g ra p h ic m e m o r ie s ,
w o u ld allo w th r e e - d im e n s i o n a l s to r a g e to b e r a p i d ly m a n ip u la te d an d f o u r
o r m o r e d im e n s io n s to b e s im u la te d f o r m e a s u re m e n t.
34
C le a r ly , th e s to r a g e m e d iu m a f f e c ts th e d a ta f o r m a ts .
In fa c t, ev en fro m
th i s p r e l im i n a r y d is c u s s io n it i s e v id e n t th a t th e e m p ir ic a l p r o p e r t i e s of
th e e n tity o r c o n d itio n b e in g e x a m in e d , th e c o n c e p t of s p a c e e m p lo y e d , th e
la n g u a g e u s e d , th e m e th o d of d e s c r ip tio n , th e d a ta f o r m a t, th e s to r a g e
m e d iu m c h o s e n , th e file s t r u c t u r e c h o s e n , a n d th e c a p a b ility f o r m a n ip u la tin g th e d a ta a r e a l l in te rd e p e n d e n t.
W ith in th i s c o n tin u u m , i t s h o u ld b e n o te d th a t th e E u c lid e a n c o n c e p t o f s p a c e ,
E u c lid e a n g e o m e try , a n d th e w id e s p r e a d u s e of tw o - d im e n s io n a l d o c u m e n ts
f o r 2, 000 y e a r s h a v e h a d a s tr o n g in flu e n c e on th e ty p e s o f s p a ti a l d a ta th a t
a c tu a lly e x i s t an d h a v e t o b e h a n d le d to d a y .
T h e s e c o n d p a r t o f th i s c h a p te r
w ill e x a m in e th e f a c t o r s th a t a f fe c t th e su p p ly a n d a v a ila b ility o f s p a tia l
d a ta an d th e fo llo w in g c h a p te r s w ill e x a m in e tr a d iti o n a l an d new te c h n iq u e s
f o r t h e i r h a n d lin g a n d m a n ip u la tio n .
T y p e s of L o c a tio n I d e n tif ie r
T o s u m m a r iz e th e c h a r a c t e r i s t i c s of e x is tin g d a ta , i t c a n b e s a id th a t fiv e
m a in ty p e s of lo c a tio n id e n tif i e r s a r e c u r r e n t ly i n u s e (F ig . 2. 2).
D ata
N ot
lo c a tio n s p e c if ic
L o c a tio n s p e c ific
E x te r n a l
in d e x
F ig . 2. 2.
1)
P o in t
L in e
A r b itr a r y
re g u la r
are a s
Irre g u la r
po ly g o n
C om m on lo c a tio n id e n tif i e r s in e x is tin g s e t s o f d ata.
T h e e x t e r n a l in d e x c o m p r is e s n o m in a l la b e ls th a t a r e g e n e r a lly d e s c r i p tiv e o f a lo c a tio n , s u c h a s th e n a m e s of a d m in is tr a tiv e a r e a s ,
s t r e e t a d d r e s s e s , c e n s u s t r a c t s , p o s ta l c o d e s , an d s o f o r th .
Such
la b e ls c a n b e u s e d to g ro u p d a ta th a t h a v e no o th e r lo c a tio n id e n tif ie r .
It i s , h o w e v e r, im p o s s ib le to t e l l th e r e l a ti v e p o s itio n o r p h y s ic a l
35
li m i t s of th e e le m e n ts w ith o u t r e f e r e n c e to a m a s t e r in d e x ( ty p ic a lly
a m ap) sh o w in g th e b o u n d a r ie s of th e n a m e d it e m s .
M ost n o n -m a p p e d
d a ta w ith a n y lo c a tio n id e n tif ie r to d a y a r e r e c o r d e d b y th i s d e s c r ip tiv e
m e th o d .
A ll th e r e m a in in g ty p e s of lo c a tio n id e n tif ie r a r e r e l a t e d e ith e r to s o m e
c o o rd in a te s y s t e m o r to o th e r d a ta e le m e n ts by one o r m o r e s p a tia l la n g u a g e s
(s e e d is c u s s io n ab o v e ).
2)
D is c r e t e p o in ts a r e b e s t e m p lo y e d a s a b s tr a c tio n s of s m a l l p h e n o m e n a ,
b u t f r e q u e n tly a r e u s e d a s s u r r o g a te s f o r l a r g e r p h en o m en a.
The
c e n tr o id of a n i r r e g u l a r a r e a , f o r e x a m p le , m a y b e u s e d a s th e l o c a tio n a t w h ic h th e c h a r a c t e r i s t i c s of th e a r e a a r e r e c o r d e d .
T h is
a p p r o a c h , u n lik e th e u s e o f n o m in a l c o d e s, a llo w s th e r e l a ti v e p o s itio n s
o f th e l a r g e r p h e n o m e n a to b e e s ta b lis h e d , b u t it d o e s n o t, o f c o u r s e ,
d e fin e t h e i r b o u n d a rie s .
S e ts of p o in ts m a y a l s o b e u s e d to r e p r e s e n t
e n t iti e s w ith one o r m o r e d im e n s io n s (fo r e x a m p le , s p o t h e ig h ts o n a
to p o g ra p h ic s u r f a c e ,
3)
o r w e a t h e r - s t a ti o n d a ta in a n a i r m a s s ) .
D a ta c a n b e a s s ig n e d to lin e s e g m e n ts .
C o m m o n ly , lin e s e g m e n ts a r e
e m p lo y e d to r e p r e s e n t f e a t u r e s s u c h a s r o a d s , ra ilw a y s , flig h t p a t h s ,
g e o lo g ic a l f a u l ts , a n d s t r e a m s .
L in e s e g m e n ts a r e u s u a lly p lo tte d o n
m a p s a n d th u s t h e i r r e l a ti v e p o s itio n s a r e r e c o r d e d w ith in a c o o r d in a te
s y s te m .
T h e y m a y , h o w e v e r, b e to p o lo g ic a lly r e l a te d an d g r a p h ic a lly
d is p la y e d w ith o u t r e f e r e n c e to c o o rd in a te s , a s o n a s t r i p m a p o f a
r o u te o r a n u n d e rg ro u n d m a p of London.
L in e s e g m e n ts a r e o n e -
d im e n s io n a l, b u t a n e tw o r k of s u c h s e g m e n ts i s a tw o - d im e n s io n a l
e n tity .
4)
A r b i t r a r y r e g u l a r a r e a s a r e u s e d to p ro v id e c e lls f o r th e lo c a l s u b d iv is io n o r g ro u p in g of s p a ti a l d a ta .
T h e ir u tility d ep e n d s o n th e s i z e
o f th e c e ll in r e l a ti o n to th e p h en o m en a b e in g r e c o r d e d .
n e c e s s a r i l y a r b i t r a r y u n it s , ty p ic a lly a g r id .
They a re
T h e p o s itio n o f th e g r id
in E u c lid e a n s p a c e c a n b e s p e c ifie d b y i t s c o r n e r c o o rd in a te s a n d th e
d im e n s io n s of th e g r id .
T h e r e g u l a r a r r a n g e m e n t of th e c e lls , th e
e a s e of e s ta b lis h in g m a r k e r s on th e g ro u n d to d e lim it th e r e g u l a r
p a t te r n , a n d th e e a s e of lo c a tin g a s p e c if ic c e ll w ith in th e s e t le d t o
t h e i r e a r l y a d o p tio n f o r th e s u b d iv is io n of p r o p e r t y (fo r e x a m p le , in
36
R o m a n c i tie s o r N o rth A m e ric a n p r a i r i e f a r m s ) , f o r p u r p o s e s o f
m i l i t a r y an d a d m in is tr a tiv e r e f e r e n c e , an d , m o re r e c e n tly , f o r t h e
g r o u p in g of d a ta in p r e p a r a tio n f o r c o m p u te r s to r a g e .
C r i t i c i s m of
th e a p p r o a c h f o r g ro u p in g c e n tr e s on th e f a c t th a t it im p o s e s a n u n r e a l
d a ta f o r m a t on th e r e a l - w o r l d p h en o m en a.
5)
I r r e g u l a r p o ly g o n s a r e s u r f a c e - d e s c r ip ti v e lo c a tio n id e n tif i e r s .
They
d if f e r f r o m lin e s e g m e n ts in th a t t h e i r b o u n d a r ie s s e p a r a t e a r e a s w ith
u n lik e c h a r a c t e r i s t i c s , w h e r e a s a lin e se g m e n t o r lin e n e tw o r k m a y
tr a v e r s e a hom ogeneous a re a .
T h e a t tr ib u t e s of a s u r f a c e c a n b e
e x p r e s s e d a s c o n tin u o u s , s in g le -v a lu e d fu n c tio n s , o r a s s te p f u n c tio n s
o f in d e p e n d e n t c o n tin u o u s v a r i a b le s .
T h e s e a r e c o m m o n ly t r e a t e d a s
e i t h e r c o n to u rs o r s e t s of la b e lle d r e g io n a l b o u n d a r ie s .
A s re g io n a l
b o u n d a r ie s , i r r e g u l a r p o ly g o n s f r e q u e n tly d e fin e a r e a s g r o u p in g d a t a
th a t a r e o th e r w is e n o t lo c a tio n - s p e c if ic (su ch a s a d m in is tr a tiv e a r e a s ,
p o s ta l z o n e s , o r c e n s u s t r a c t s ) .
U se d a s is o li n e s , i r r e g u l a r p o ly g o n s
e x te n d th e c a p a b ilitie s of th e tw o -d im e n s io n a l d o cu m en t f o r m a t in th a t
th e y p r e s e n t a u s e fu l a p p ro x im a tio n of a w a r p e d p la n e ; to p o g r a p h ic
c o n to u rs a r e p ro b a b ly th e m o s t r e a d i ly u n d e rs to o d e x a m p le .
T h e s e lo c a tio n id e n tif i e r s c a n a l l b e g r a p h ic a lly r e c o r d e d o n a tw o - d im e n s io n a l m e d iu m .
T h e g r a p h ic e x p r e s s io n of th e s p a ti a l la n g u a g e c a n b e a n
e x t r e m e l y c o m p a c t f o r m of n o ta tio n .
T h e in fo rm a tio n c o n te n t o f a li n e c a n
b e m a n y t i m e s h ig h e r th a n , f o r e x a m p le , a n u m e r ic a l e x p r e s s io n th a t u s e s
th e s a m e a m o u n t o f s p a c e on a d o cu m en t.
A ny of th e g r a p h ic f o r m s of lo c a tio n id e n tif i e r s m e n tio n e d a b o v e c a n b e
m ix e d to f o r m a c o m p o s ite d e s c r ip tio n of a s u r f a c e .
T h e y a r e , i n f a c t , th e
s tu ff th a t m a p s a r e m a d e of, an d m a p s h a v e s e r v e d m a n w e ll a n d c o n tin u e
to do s o .
A s tr o n g a r g u m e n t c a n b e m a d e th a t g ra p h ic r e p r e s e n t a ti o n o f
s p a ti a l d a ta fo llo w s m a n 's p e r c e p tu a l u n d e rs ta n d in g of s p a c e , a n d th u s i s
e a s y to r e a d a n d a s s im i la t e .
T h e e a s e w ith w h ich m a n c a n e x t r a c t d a t a f r o m
th e g r a p h ic f o r m a t w ill b e e x a m in e d in C h a p te r 3.
A ll th e ab o v e ty p e s o f lo c a tio n id e n tif ie r w ill b e e x a m in e d in g r e a t e r d e ta il
in th e fo llo w in g c h a p te r s of th e t h e s i s .
A s h a s b e e n p o in te d o u t, th e y d o n o t
r e p r e s e n t a l l p o s s ib le c a te g o r ie s of lo c a tio n id e n tif ie r ; th e y m a y n o t e v e n b e
th e m o s t u s e f u l w ay to s p e c ify lo c a tio n in a l l in s ta n c e s .
T h e y d o , h o w e v e r.
37
r e f l e c t th e c o n c e p t o f s p a c e , g e o m e tr y , a n d ty p e of g ra p h ic p o r tr a y a l th a t
h a v e fo u n d g e n e ra l a c c e p ta n c e an d u n d e rlie th e m a in bod y o f e x is tin g lo c a tio n s p e c ific d a ta .
T h e r e m a in in g p a r t of th is c h a p te r w ill e x a m in e th e f a c t o r s
th a t in flu e n c e th e o v e r a l l s u p p ly a n d a v a ila b ility of lo c a tio n - s p e c if ic d a ta .
S U P P L Y AND A V A IL A B IL IT Y O F DATA
T h e s t a t e of d e v e lo p m e n t of s p a ti a l d a ta h a n d lin g te c h n iq u e s w ill b e e x a m in e d
l a t e r , b u t i t s h o u ld b e m a d e c l e a r a t th e o u ts e t th a t th e u s e f u ln e s s o f s p e c if ic
te c h n iq u e s d e p e n d s to a c o n s id e r a b le e x te n t o n th e su p p ly o f d a ta th a t m u s t
b e h a n d le d .
T h is m a y v a r y s u b s ta n tia lly f r o m c o u n try t o c o u n try .
It is not
p o s s ib le w ith in th e s c o p e o f th i s th e s i s to e x a m in e th e d a ta s u p p lie s g e n e ra te d
b y v a r i o u s c o u n t r ie s .
A b r i e f e x a m in a tio n w ill, h o w e v e r, b e m a d e o f th e
f a c t o r s th a t in flu e n c e th e p r o v is io n of s p a tia l d a ta , s o th a t th e e x is tin g
ra n g e o f v a r i a ti o n c a n b e b e t t e r u n d e rs to o d .
T h e c o n d itio n s a n d c i r c u m s ta n c e s th a t u n d e rlie d a ta su p p ly a r e co m p le x an d
in te r d e p e n d e n t.
F o r c o n v e n ie n c e , h o w e v e r, th e y ca n b e g ro u p e d in to s ix
b r o a d c a te g o r ie s : p e r c e iv e d n e e d f o r d a ta ; c o n s tr a in ts on d a ta g a th e rin g ;
c o n s tr a in ts of c a p a b ility f o r g a th e rin g ; c o n s tr a in ts on v a lid ity ; p h y s ic a l
h a n d lin g c h a r a c t e r i s t i c s ; an d c o n s tr a in ts on u s e .
T h e c a te g o r ie s c a n b e
r e g a r d e d a s v a r i a b le s th a t a r e c lo s e ly in t e r r e l a t e d an d to g e th e r d e te r m in e
s p a t i a l d a ta a v a ila b ility .
T h e y a r e il lu s tr a t e d in th e d ia g r a m (F ig . 2. 3).
S O U R C E C H A R A C T E R IS T IC S
(1)
P e rc e iv e d
need
fo r
d a ta
F ig . 2. 3.
(2)
(3 )
G a th e rin g
cons tra in ts
G a th e rin g
c a p a b ility
R E S U L T IN G DATA
C H A R A C T E R IS T IC S
(5)
(4)
P h y s ic a l
V a lid ity
h a n d lin g
conc h a ra c s tra in ts
te ris tic s
(6)
U se
cons tra in ts
D a ta
s u p p ly an d
a v a ila b ility
V a r ia b le s th a t in flu e n c e th e c h a r a c te r an d a v a ila b ility o f
s p a ti a l d a ta g a th e r e d b y g o v e rn m e n ts .
S o u rc e C h a r a c t e r i s t i c s
P e r c e i v e d n e e d f o r d a ta .
T h e s p a ti a l d a ta f o r w h ich a g o v e rn m e n t h a s a
" p e r c e iv e d n e e d " a r e q u ite s im p ly th e d a ta th a t a g o v e rn m e n t th in k s it n e e d s
a n d i s p r e p a r e d to p a y f o r .
T h e y a r e r e l a t e d to th e ty p e an d le v e l o f
38
e c o n o m ic d e v e lo p m e n t of th e c o u n try , i t s p o litic a l a n d s o c ia l a c tiv i tie s , an d ,
a s a s p e c i a l p a r t of th e s e , i t s m i lit a r y h i s t o r y an d a s p ir a tio n s .
T h e to t a l
a m o u n t o f e x is tin g s p a ti a l d a ta i n a c o u n try r e f l e c ts i t s h is t o r i c a l s e q u e n c e
o f p e r c e iv e d n e e d s a n d , to a l e s s e r e x te n t, i t s view of th e f u tu r e .
An o b v io u s d iffic u lty in p ro c e e d in g r ig o r o u s ly w ith a d is c u s s io n o f n e e d s is
th e la c k o f a n y w id e ly a c c e p te d s c a l e of e c o n o m ic , p o litic a l, s o c ia l, o r
m i l i t a r y d e v e lo p m e n t, a lo n e o r in c o m b in a tio n .
A c o n tin u u m o f s o m e k in d
m a y ex i s t , a s a p a th t r a c e d in a c o m p le x , m u ltid im e n s io n a l p e r c e p tu a l s p a c e .
T h e r e l a ti o n s h i p b e tw e e n s u c h a s c a l e a n d e x is tin g s p a ti a l d a ta w o u ld p r o b a b ly n o t b e l i n e a r .
I t i s th u s p r a c t i c a l o n ly to in d ic a te b r ie f ly th e r a n g e of
p o s s i b ili tie s a n d to c o m m e n t o n t h e i r r e l a tio n s h ip to d a ta su p p ly .
L e v e ls of e c o n o m ic d e v e lo p m e n t a m o n g n a tio n s c a n c o n v e n ie n tly b e th o u g h t
to r a n g e f r o m d o m in a n tly s u b s is te n c e e c o n o m ie s , th ro u g h p r im a r y e c o n o m ie s w ith e x t r a c ti v e i n d u s tr i e s an d s p e c ia liz e d food p ro d u c tio n , t o c a p ita l in te n s iv e i n d u s tr i a l e c o n o m ie s , a n d te c h n o lo g ic a lly in te n s iv e e c o n o m ie s .
C o m m e r c ia liz a tio n in th e e c o n o m y g e n e r a lly in c r e a s e s a s o v e r a l l r e l ia n c e
on s u b s is te n c e fo o d p ro d u c tio n d e c r e a s e s .
S o m ew h at s im p l is tic a ll y , i t c o u ld b e s u g g e s te d th a t th e p r im a r y in s ti n c ts
th a t m o tiv a te a g o v e rn m e n t to g a th e r s p a ti a l d a ta a r e t e r r i t o r i a l c o n tr o l
a n d ta x a tio n .
A t th e lo w e r e n d o f th e e c o n o m ic s c a l e , s p a ti a l d a ta a r e
r e q u i r e d f o r th e ta x a tio n o f la n d a n d f o r th e e s ta b lis h m e n t o f t e r r i t o r i a l
b o u n d a r ie s w ith in w h ic h ta x e s m a y b e le v ie d .
T h e n e x t s te p r e l a t e d to
e c o n o m ic d e v e lo p m e n t i s th e a c q u is itio n o f d a ta c o n c e rn in g th e e x p lo ita b le
r e s o u r c e s o f th e la n d , i t s c l im a te , v e g e ta tio n , s o il, geo lo g y , w a te r , a n d s o
f o r th .
In itia lly , th e s e a r e u s u a lly h u r r i e d e x p lo r a to r y s u r v e y s , w ith a h ig h
s u b je c tiv e c o n te n t u s e d to d ir e c t th e in v e s tm e n t of e f f o r t ( c a p ita l).
U s u a lly ,
h o w e v e r , th e y la y th e fo u n d a tio n s f o r c o n tin u o u s d a ta g a th e r in g in t h e i r
r e s p e c t iv e d is c ip lin e s .
T h e i n i t i a l g ro w th of c o m m e r c ia liz a tio n b r in g s w ith it th e n e e d f o r s p a ti a l
d a ta o n tr a n s p o r t a ti o n r o u te s (w hich m a y in s o m e in s ta n c e s p r e c e d e t e r r i t o r i a l in v e s tig a tio n of a n y k in d ).
T h e f i r s t n e e d is f o r d a ta f r o m s im p le
t r a v e r s e s , th e n to p o g ra p h ic d a ta f o r r o a d , r a i l , a n d c a n a l b u ild in g , a n d f o r
w a te r a n d a i r n a v ig a tio n .
A s p o p u la tio n d e n s ity i n c r e a s e s , th e n e e d f o r a
39
m o r e d e ta ile d s p e c if ic a tio n o f th e ta x b a s e a r i s e s .
F o r m a l p o p u la tio n c e n s u s ,
a g r i c u l t u r a l c e n s u s , a n d c o m m e r c i a l c e n s u s b y ta x a b le a r e a a r e g e n e ra te d .
T h e g ro w th o f c a p ita l- in te n s iv e in d u s tr ie s (an d a new ta x b a s e ) in c r e a s e s
th e n e e d f o r a c e n s u s of in d u s tr y .
A s in d u s tr y m a k e s d e m a n d s o n n a tio n a l
an d h u m a n r e s o u r c e s , a n d c o n tro l o v e r t h e i r e x p lo ita tio n is d e e m e d p ru d e n t,
m o r e d e ta ile d s u r v e y s a r e r e q u i r e d .
G o v e rn m e n t- c o n tr o lle d s u r v e y s of
lo g g in g a n d r e a f f o r e s t a ti o n (a s o p p o s e d to ti m b e r r e s o u r c e s u rv e y s )
il l u s t r a t e th i s n e e d .
A s te c h n o lo g ic a l d e v e lo p m e n t a n d s o c ia l liv in g s ta n d a r d s in c r e a s e , t h e r e i s
a n e e d f o r d a ta o n w h ic h to b a s e r e s e a r c h .
S p a tia l d a ta o n f o r e s t p e s ts ,
c ro p d i s e a s e s , a n d h u m a n m e d ic a l a n d s o c ia l c o n d itio n s a r e ty p i c a l r e s p o n s e s to th i s n e e d .
A s c o m m u n ic a tio n s w ith in a c o u n tr y d e v e lo p a n d a s
r e g i o n a l e c o n o m ic d i s p a r i t i e s b e c o m e e v id e n t to th e p o p u la tio n , th e n ee d
a r i s e s to g a th e r s p a t i a l d a t a o n a re g io n a l b a s i s .
T h e d e v e lo p m e n t of
c o m p le x u r b a n s o c i e t i e s w ith t h e i r in h e r e n t s t r a i n s b r in g s a d e s i r e f o r
c o n tr o l of s p a t i a l i n t e r a c t io n s , a n d th u s a n e e d f o r d e ta ile d s p a ti a l d ata.
T h e h ig h e r l e v e l s of e c o n o m ic d e v e lo p m e n t a r e c h a r a c te r iz e d b y in te n s e
c o m p e titio n b e tw e e n p o te n tia l la n d u s e s a n d t h i s c r e a te s th e n e e d f o r d e ta ile d
s p a ti a l d a t a o n w h ic h to b a s e d e c is io n s .
W id e r c o n c e r n s of e n v ir o n m e n ta l
d e g r a d a tio n h a v e in i tia te d th e g a th e r in g o f d a t a o n c o n d itio n s o f w ild life
h a b i ta t , r e c r e a t i o n a l p o te n tia l, an d , m o r e r e c e n tly , th e e f f e c ts o f m a n p r o d u c e d p o llu ta n ts .
I t i s im p lic it i n th e p h r a s e " r e g io n a l e c o n o m ic d is p a r i tie s " th a t c o u n tr ie s ,
p a r t i c u l a r l y l a r g e o n e s , do n o t d e v e lo p h o m o g e n e o u s ly .
W ith in a n y one
n a tio n t h e r e m a y b e s e v e r a l d is tin c t le v e ls of e c o n o m ic d e v e lo p m e n t, an d
h e n c e d if f e r e n t p e r c e iv e d n e e d s f o r s p a ti a l d a ta in v a r i o u s p a r t s o f th e
c o u n try .
A s w e ll a s v a r i a ti o n s i n th e le v e ls o f e c o n o m ic d e v e lo p m e n t, t h e r e a r e v a r i a tio n s in ty p e s o f p o li tic a l a n d s o c ia l a c tiv ity .
C o u n trie s w ith a lo n g h is to r y
of s e lf - g o v e r n m e n t m a y h a v e s e t s of d a ta e n t ir e l y d if fe re n t f r o m th o s e o f
n e w ly in d e p e n d e n t c o u n t r ie s .
T h e l a t t e r m a y h a v e d a ta d e te r m in e d b y w id e ly
d iff e re n t f o r e i g n p o li c ie s o f th e p r e v io u s c o lo n ia l a d m in is tr a tio n s .
At th e
o th e r e x t r e m e , s o m e s p a r s e l y in h a b ite d a r e a s m a y b e s u r p r is in g ly w e ll
40
s u r v e y e d s im p ly b e c a u s e th e p o l iti c a l e x ig e n c ie s r e q u ir e d e v id e n c e
o f te r rito r ia l p o s s e s s io n . D if f e r e n c e s in p o litic a l s tr u c tu r e r e s u lt in
d if f e r e n c e s in d a ta g a t h e r in g . S tr o n g c e n tr a l g o v e r n m e n t n e c e s s it a te s
g o o d c o m m u n ic a tio n s a n d e ffic ie n t d a ta g a th e rin g . N a p o le o n 's in n o v a tiv e
d a t a g a th e r in g ( a n d a d m in is tr a tiv e ) s tr u c tu r e o f F r e n c h " D é p a r te m e n ts "
s till u n d e rlie s c o lle c tio n o f d a ta in F ra n c e . T h e p o litic a lly o rie n te d o ffic ia l d a ta
g a th e re r fo r e a c h c ity b lo c k fa c e d u rin g th e p e rio d 1 9 3 5 -4 5 in G e rm a n y
w a s a n e x tre m e e x a m p le o f c o lle c tio n o f s p a tia lly p re c is e d e m o g r a p h ic
statistics, implemented by an authoritarian regime. M ilitary
e x i g e n c ie s h a v e h a d a s t ro n g i n f lu e n c e o n th e p e r c e i v e d n e e d s f o r s p a ti a l
d a ta . T h e s u p p ly o f te rra in d a ta w ith in a n y n a tio n fre q u e n tly re fle c ts its
i n v o l v e m e n t ( e ith e r d e lib e r a te o r in v o lu n ta r y ) in w a r f a r e . I t m a y w e ll b e ,
f o r in s ta n c e , th a t V ie tn a m c u r r e n tly h a s th e m o s t e x te n s iv e a n d u p - to - d a te
s u p p l i e s o f t e r r a in d a ta o f a n y c o u n tr y in t h e w o r ld a t a s im i la r le v e l o f
e c o n o m ic d e v e lo p m e n t. T h e in f lu e n c e o f t h e m i lit a r y in d a t a g a t h e r in g
is n o t n e c e s s a r ily b a d . P e r h a p s th e c la s s ic c a s e is th e O r d n a n c e S u r v e y
in G r e a t B rita in , w h ic h h a s fu rn is h e d th a t c o u n try (a n d o th e rs ) w ith
e x e m p la ry to p o g ra p h ic m a p s . T h e first m o d e rn p re se n t-la n d -u s e s u rv e y o f
G re a t B rita in w a s a n in d ire c t re s u lt o f th e s tre s s o f w a r. S im ila rly ,
t h e w i d e s p r e a d p la n im e tr ic m a p p in g p r o g r a m o f n o r th e r n C a n a d a w a s
fu n d a m e n ta lly d e p e n d e n t o n th e n e e d fo r w a rtim e a e ria l n a v ig a tio n . T h e m ilita ry
c o m m u n ity h a s c o n s is te n tly n u rtu r e d th e d e v e lo p m e n t o f s p a tia l d a ta
g a t h e r in g te c h n iq u e s , in c lu d in g th e e a r lie s t u s e s o f a e r ia l p h o to g r a p h y ,
p h o to g r a m m e tr y , in f r a r e d p h o to g r a p h y , m ic r o w a v e tr ia n g u la tio n , s a te llite
s e n s o r p la tfo rm s , a n d la s e r d is ta n c e m e a s u re m e n t, a ll o f w h ic h
are ro u tin ely u se d in n o n -m ilitary sp atial d ata g ath erin g to d ay .
C le a r ly , th e p e r c e iv e d n e e d s o f g o v e r n m e n t a r e c o m p le x a n d r e f le c t th e
h is to r y o f th e c o u n t r y , i ts in t e r a c t io n w ith i ts n e ig h b o u r s , a n d i ts p r e s e n t
m ix tu re o f le v e ls o f e c o n o m ic d e v e lo p m e n t.
G a t h e r i n g c o n s tr a i n ts . G a th e r i n g c o n s tr a in t s a r e c o n d i tio n s th a t a f f e c t th e
c o s t, le n g th o f tim e , o r p r a c tic a lity o f g a th e r in g s p a tia l d a ta in a n y c o u n tr y .
P h y s ic a l e n v ir o n m e n ta l c o n s tr a in ts a r e p e r h a p s th e m o s t e a s ily r e c o g n iz e d ,
th o u g h th e ir a c tu a l e f f e c ts o n th e s p a tia l d a ta g a th e r in g p r o c e s s a n d th e
s u b s e q u e n t a v a ila b ility o f v a r io u s ty p e s o f d a ta a r e n o t s o w id e ly u n d e r s to o d .
41
T h e s i z e of a c o u n try d o e s n o t p r o h ib it d e ta ile d lo c a l s p a ti a l d a ta g a th e r in g ,
b u t i t d o e s d r a m a ti c a ll y a ffe c t th e c o s t an d tim e of o v e r a l l r e c o n n a is s a n c e
s u r v e y , w h ic h i s a f o r m of h i g h - r i s k d a ta p ro s p e c tin g .
N a tio n s w ith a
l a r g e a r e a l e x te n t f r e q u e n tly s p e n d a h ig h p e rc e n ta g e ' of t h e i r a v a ila b le
d a ta g a th e r in g b u d g e t o n th i s le v e l of s u r v e y .
T h e e x te n t a n d a g e o f th e
d if f e r e n t ty p e s of d a ta a v a ila b le m a y th u s v a r y w ith th e s iz e o f th e n a tio n .
C lim a tic e x t r e m e s of h e a t, c o ld , d r y n e s s , a n d w e tn e s s a r e w e ll- u n d e r s to o d
p h y s ic a l c o n s tr a in ts .
S om e of th e s id e - e f f e c ts o f th e s e e x tr e m e s a l s o a c t
a s im p o r ta n t c o n s tr a in ts .
T h e s u b a r c t ic a n d a r c t i c a r e a s a r e n o t o n ly
c o ld b u t d a r k f o r lo n g p e r io d s of th e y e a r .
A s one a p p ro a c h e s th e m a g n e tic
p o le s , t r a d iti o n a l f o r m s of n a v ig a tio n a r e u n r e lia b le an d r a d i o c o m m u n ic a tio n s a r e s o m e tim e s d is r u p te d b y
lo w e r la tit u d e s .
e le c tric
s t o r m s , w h ich a r e r a r e in
H u m id tr o p i c a l c o n d itio n s n o t o n ly r e s t r i c t g ro u n d
s u r v e y b u t th e a s s o c ia te d clo u d c o v e r in h ib its a e r i a l s u r v e y .
T h e o n ly
w id e s p r e a d a e r i a l view of P a n a m a , f o r in s ta n c e , h a s co m e o n ly s in c e
c lo u d - p e n e tr a tin g p -b a n d r a d a r s e n s o r s h a v e b e e n e m p lo y e d .
S u rfa c e tr a f f i c a b i lit y i s c l e a r l y a ffe c te d b y c o n s tr a in ts s u c h a s m o u n ta in s ,
ic e f i e l d s , s a n d d e s e r t s , m u s k e g , s w a m p , a n d v a r io u s f o r m s o f d e n s e
v e g e ta tio n c o v e r.
T h e a u th o r w a s o n c e l e a d e r o f a te a m o f p h o to - i n te r -
p r e t e r s w ho c a r r i e d o u t a p h o to -g e o lo g ic a l s tu d y of 5 0 ,0 0 0 s q u a r e m ile s
o f n o r t h e r n O n ta rio in C a n a d a .
T h e p r i m a r y p u r p o s e of th e w o rk w as
s im p ly to id e n tif y th e r a r e r o c k o u tc ro p s i n th e m u s k e g s o th a t h e l ic o p t e r b o r n e g e o lo g is ts c o u ld e x a m in e a c tu a l b e d ro c k .
P a r a d o x ic a lly , th e s a m e
h e l ic o p t e r s c o u ld n o t b e u s e d in th e o u tc ro p -a b u n d a n t h ig h m o u n ta in a r e a s
in B r i t i s h C o lu m b ia , b e c a u s e th e a i r a t h ig h a ltitu d e w as to o th in f o r
e f f ic ie n t u s e of r o ta r y - w in g a i r c r a f t .
D e n s e v e g e ta tio n c o v e r n o t o n ly
h in d e r s s u r f a c e t r a f f i c a b i lit y b u t c a n c o m p le te ly o b s c u re a e r i a l o b s e r v a tio n
of te rra in .
N ot a few c o n to u r m a p s of t e r r a i n h e ig h t r e p r e s e n t th e s u r f a c e
of th e v e g e ta tio n ca n o p y r a t h e r th a n th e s u r f a c e of th e g ro u n d 0 to 300
f e e t b e lo w .
D a ta g a th e r in g in la r g e , s p a r s e l y in h a b ite d o r u n in h a b ite d
a r e a s in v o lv e s a h ig h c o s t f o r lo g i s t ic a l s u p p o r t of th e s u r v e y p e r s o n n e l.
T h e e f f e c t o f t h i s i s r a r e l y fu lly a p p r e c ia te d .
A t a tim e w h en p e t r o l w as
r e a d i l y a v a ila b le a t 50c p e r g a llo n in in h a b ite d p a r t s o f C a n a d a , f o r
e x a m p le , th i s fu n d a m e n ta l c o m m o d ity f o r tr a n s p o r t a ti o n , w a r m th , an d
42
co o k in g o r f u e l c o s t $ 3 .0 0 p e r g a llo n in th e C a n a d ia n a r c t i c .
T he c o st of
a e r i a l s u r v e y f o r th i s it e m a lo n e w a s th u s s ix o r m o r e ti m e s h ig h e r p e r
s q u a r e m ile in th e u n in h a b ite d a r e a th a n in th e in h a b ite d a r e a to th e so u th .
A ll of th e ab o v e ty p e s of p h y s ic a l c o n s tr a in t c o n trib u te to t h e v a r i a b il ity
in ty p e an d s u p p ly of s p a ti a l d a ta , a n d a l s o a ff e c t th e e r r o r s o f o b s e r v a tio n a n d m e a s u r e m e n t in th e d a ta a c tu a lly g a th e re d .
S im ila r ly , t h e r e i s
a d is tin c t d if f e re n c e in r e l i a b i l i t y b e tw e e n m e a s u r e m e n ts o f s t a t i c a n d
n o m a d ic h u m a n p o p u la tio n s , an d b e tw e e n a n im a l p o p u la tio n s r e s t r i c t e d
to one fe e d in g a r e a a n d m i g r a to r y o n e s .
L e s s o b v io u s a r e th e p o li tic a l an d s o c ia l c o n s tr a in ts of d a t a g a th e r in g w ithin,
a c o u n try .
A d is tin c tio n i s m a d e b e tw e e n th e c o n s tr a in ts th a t a f f e c t th e
g a th e r in g of d a ta a n d th o s e th a t a ffe c t t h e i r u s e a n d a v a ila b ility a f t e r th e y
h av e b e e n g a th e r e d .
T h e l a t t e r w ill b e c o n s id e r e d s e p a r a t e ly .
W ith in n a tio n s , p a r t i c u l a r l y th o s e w ith f e d e r a l f o r m s o f g o v e r n m e n t,
t h e r e m a y b e s e v e r a l c l e a r l y e s ta b lis h e d ju r i s d i c ti o n s , e a c h w ith r e s p o n s i b i l i t i e s f o r c e r t a i n ty p e s of d a ta c o lle c tio n .
W ith in C a n a d a , f o r e x a m p le ,
e a c h p r o v in c e i s c o n s titu tio n a lly r e s p o n s ib le f o r d a t a r e l a t i n g to i t s ow n
n a tu ra l re s o u rc e s .
W h e re d if fe re n t p o litic a l p r i o r i t i e s e x i s t w ith in th e
v a r io u s j u r i s d i c ti o n s , d iff e re n t le v e ls of s p a t i a l d a ta a v a ila b i lit y c a n a n d
do r e s u l t .
D iff e r e n t c l a s s i f ic a t io n s m a y b e a d o p te d .
D if f e r e n t u n it s o f
m e a s u r e , t i m e s o f s u r v e y , le v e ls o f d e ta il, a n d ty p e s o f d a ta g a th e r in g
m a y r e s u l t in a p a tc h w o rk q u ilt of d a ta a v a ila b ility w ith in o n e n a tio n .
O ne
of th e m a jo r a c h ie v e m e n ts of th e C a n a d a L a n d In v e n to ry b e tw e e n 1962 a n d
1969, f o r e x a m p le , w a s th e p e r f o r m a n c e of s e p a r a t e n e g o tia tio n s w ith
e a c h p ro v in c e th a t le d to u n if o rm c l a s s i f ic a t io n s of p r e s e n t la n d u s e ,
a g r i c u l t u r a l c a p a b ility , f o r e s t c a p a b ility , w ild life s u ita b ility , a n d r e c r e a t io n a l p o te n tia l of th e la n d a c r o s s C an a d a.
I f n e g o tia tio n s h a d b e e n
c o n d u c ted b y d if f e re n t p e r s o n n e l, in a d iffe re n t p o li tic a l c lim a te , o r a t a
d if fe re n t ti m e in h is to r y , t h e i r o u tc o m e m ig h t h a v e b e e n l e s s f o r tu n a te
a n d th e a v a ila b ility o f s p a ti a l d a ta in C a n a d a w o u ld b e m e a s u r a b ly d if f e re n t.
S o c ia l c o n s tr a in ts on d a ta g a th e r in g a ls o v a r y w id e ly .
T h e re lia b ility of
d a ta c o lle c te d b y th e U. S. B u r e a u of C e n s u s f r o m b la c k g h e tto s i n th e
U n ite d S ta te s s u f f e r s in th e s a m e w ay a s th e c e n s u s d a t a f r o m C o r s ic a
43
g a th e r e d b y th e G o v e rn m e n t of F r a n c e (IN SE E ).
T h e h o s til ity o f a p o p u -
la tio n to a u th o r ity c a n b e a s e v e r e c o n s tr a in t on d a ta g a th e r in g .
In
c o n t r a s t is th e 4 0 0 - y e a r - o l d tr a d iti o n of th e C e n tr a l P o p u la tio n R e g i s t e r
in S w eden, w h e re d a ta c o lle c te d on p o p u la tio n a t tr ib u t e s a r e n o t on ly
d e ta ile d an d g e n e r a lly r e l ia b l e , b u t a r e f r e e l y a v a ila b le to th e p u b lic .
S im ila r ly , th e h ig h r a t e of r e s p o n s e to th e p o s ta l m e th o d o f c e n s u s u s e d
i n C a n a d a w o u ld b e to t a ll y im p o s s ib le in a c o u n try w ith a h ig h p e rc e n ta g e
of il l i t e r a c y .
T h e a b o v e e x a m p le s do n o t e x h a u st th e l i s t o f c o n s tr a in ts th a t a ffe c t th e
g a th e r in g of s p a ti a l d a ta .
e a c h c o u n tr y i s u n iq u e .
T h e y a r e , h o w e v e r, s u ffic ie n t to in d ic a te th a t
E a c h c o u n try h a s i t s ow n m ix tu r e o f c o n s tr a in ts
th a t h a v e to b e o v e rc o m e if s p e c if ic ty p e s of d a ta a r e n e e d e d , a n d th a t
r e s u l t i n s u b s t a n ti a l v a r ia tio n s in th e ty p e an d c h a r a c t e r of d a ta su p p ly .
G a th e rin g c a p a b ility .
T h e c a p a b ility of a c o u n try to g a th e r s p a ti a l d a ta
d e p e n d s on th e g a th e r in g te c h n iq u e s a n d th e am o u n t of fu n d s a v a ila b le a t
th e ti m e w h en th e n e e d f o r th e d a ta i s p e r c e iv e d .
T h e r a p i d d e v e lo p m e n t
of s p a t i a l d a ta g a th e r in g te c h n iq u e s d u r in g th e p a s t c e n tu r y , an d p a r t ic u l a r ly
i n th e p a s t 50 y e a r s , w ill b e e x a m in e d v e r y b r ie f ly b elo w .
B e c a u s e of
t h i s r e c e n t d e v e lo p m e n t, th e o v e r a l l s u p p lie s 1 o f s p a ti a l d a ta a v a ila b le
i n v a r i o u s c o u n t r ie s g e n e ra lly r e f l e c t t h e i r d iv e r s e n e e d s in th e p a s t
c e n tu r y (an d h e n c e t h e i r r e c e n t e c o n o m ic a n d s o c ia l s ta te ) r a t h e r th a n
e a r l i e r i n t h e i r h is to r y .
D iv e r s ity a l s o s te m s f r o m th e f a c t th a t th e a p p li-
c a tio n of d iffe re n t d a ta g a th e r in g te c h n iq u e s r e s u l t s in d if f e re n t d a ta
p r o d u c ts .
F o r e x a m p le , a g e o lo g ic a l m a p r e s u lt in g f r o m g ro u n d s u r v e y
a lo n e w ill p r o b a b ly b e d iffe re n t f r o m o n e p r o d u c e d b y a i r - p h o t o - i n t e r p r e t a tio n , w h ic h w ill b e d if f e re n t f r o m one u tiliz in g b o th te c h n iq u e s , w h ich
w ill b e d iffe re n t a g a in f r o m one in c o r p o r a tin g g e o p h y s ic a l m e a s u r e m e n ts
of b e d r o c k a t t r i b u t e s .
In s h o r t, d iff e re n t d a ta g a th e r in g te c h n iq u e s
p ro v id e p ro d u c ts th a t h a v e t h e i r ow n c h a r a c t e r i s t i c s an d li m ita tio n s , an d
th e s e a f fe c t th e s u p p ly a n d n a t u r e of th e a v a ila b le d a ta in w ay s th a t m a y
o r m a y n o t b e a p p a r e n t to th e u s e r .
(a)
S p a tia l d a ta g a th e r in g te c h n iq u e s .
S p a tia l d a ta g a th e r in g r e l i e s upon
th e te c h n o lo g ie s of d a ta s e n s in g , t r a n s p o r t a ti o n a n d c o m m u n ic a tio n , and
1. T h is a p p lie s to s p a ti a l d a ta w ith a slow r a t e of d e c a y , s u c h a s c o n to u r
m a p s of t e r r a i n , g e o lo g ic a l m a p s , s o il m a p s , e t c . , a s w e ll a s to m o re
v o la tile d a ta .
44
d a ta re c o r d in g .
D a ta g a th e r in g m e th o d s a r e th e a p p lic a tio n o f su c h
te c h n o lo g y .
T h e f i r s t of th e s e f a c t o r s , d a ta s e n s in g , c a n b e d e fin e d a s th e a b ility to
m a k e a n o b s e r v a tio n , a n d , b y e x te n s io n , th e a b ility to c a lib r a t e th e
o b s e r v a tio n (p ro v id e a m e a s u r e ) .
o r in s tr u m e n ta l.
T h e d e v ic e s e m p lo y e d c a n b e h u m a n
T h e r e la tio n s h ip b e tw e e n th e m i s il l u s t r a t e d in F ig . 2 .4 .
HUM AN
IN ST R U M EN T
SENSING
H u m an
sen so ry
o b s e r v a tio n
C A LIBRA TIO N
E x te n d e d h u m a n
sen so ry
o b s e rv a tio n
R e c o g n itio n
E s tim a tio n
C o u n tin g
C a lib r a tio n of
hum an
o b s e r v a tio n
A n c ie n t and
m o d e rn s k ill
F ig . 2. 4 .
S e n s in g of p h en o m en a
u n d e te c ta b le b y
hum an sen ses
C a lib r a te d
in s tr u m e n t
re sp o n se
W id e s p re a d
p r a c t ic e
M o re r e c e n t d e v e lo p m e n t. R e la tiv e ly
lim ite d p r a c t ic e
(w ith s o m e e x c e p tio n s , e .g .,
c o m p a s s)
R e la tio n s h ip b e tw e e n h u m a n a n d in s tr u m e n t c a p a b ilitie s
f o r s e n s in g and c a lib r a t in g s p a ti a l d a ta .
It i s n o t n e c e s s a r y to c a ta lo g u e th e d if fe re n t c a p a b ili tie s , b u t s e v e r a l
c o m m e n ts c a n b e m a d e on t h e i r ra n g e .
A lth o u g h th e p h y s ic a l c o n s tr a in ts
on d a ta g a th e r in g h a v e r e m a in e d m o r e o r l e s s c o n s ta n t, th e su p p ly o f th e
m o s t c o m m o n s e n s in g d e v ic e , m a n h im s e lf , h a s i n c r e a s e d ex p o n e n tia lly .
I t i s a t r u i s m to s a y th a t m o r e h u m a n s h a v e liv e d , b e c o m e l i t e r a t e , an d
p a r t ic i p a te d in d a ta g a th e r in g in th e p a s t 100 y e a r s th a n th e to t a l s o
o c c u p ie d s in c e th e b e g in n in g o f t i m e .
I t i s c l e a r , h o w e v e r, th a t th e
g ro w th of m a n k in d n o t o n ly g e n e r a te s d e m a n d s f o r d a ta , b u t a ls o c r e a te s
th e d e v ic e s f o r g a th e r in g th e m .
In s tr u m e n ta tio n h a s e x te n d e d th e r a n g e of p o s s ib le s e n s in g , b y ex ten d in g
h u m a n s e n s iti v ity th ro u g h d e v ic e s s u c h a s th e te le s c o p e , m ic r o s c o p e , an d
d e n s ito m e te r , w h ic h a r e s e n s itiv e to lig h t; th e th e r m o m e te r , w h ich s e n s e s
1. I t i s n e c e s s a r y to d if f e re n tia te b e tw e e n h u m a n s e n s in g c a p a b ility an d
h u m a n d a ta p r o c e s s in g c a p a b ility a t th i s p o in t. T h e l a t t e r q u ite p o w erfu l
c a p a b ility a d d s g r e a t u tility to th e r e l a ti v e ly li m it e d f o r m e r o n e. T h e
c h a r a c t e r i s t i c s o f h u m a n a n d m a c h in e - a id e d c a p a b ilitie s to h a n d le s p a tia l
d a ta w ill b e e x a m in e d in th e fo llo w in g c h a p te r s o f th e t h e s i s .
45
h e a t; th e a n e m o m e te r , w h ich m e a s u r e s flow ; th e g r a v i m e t e r , w h ic h
r e s p o n d s to g r a v ity ; th e e c h o -s o u n d e r, w h ich u s e s an d d e te c ts so u n d ;
an d p o llu tio n d e te c tio n d e v ic e s w h ich r e s p o n d to c h e m ic a l o d o u r s . I n s t r u m e n ts a l s o e x te n d h u m a n s e n s iti v ity b y s e n s in g p h e n o m e n a th a t m a n
c a n n o t d e te c t, s p e c if ic a lly e n e rg y w ave f o r m s s u c h a s m a g n e tic f ie ld s .
X - r a y s , g a m m a r a y s , r a d io w a v e s , in f r a r e d an d u ltr a v io le t r a d ia tio n ,
a n d c h e m ic a l a n d p h y s ic a l p r o p e r t ie s s u c h a s m i n e r a l c o n te n t a n d
e le c tr ic a l re s is tiv ity .
A lth o u g h a l l th e s e ty p e s of s e n s in g a r e u s e d to g a th e r d a ta c o n c e r n in g
a t t r i b u t e s of th e e n v iro n m e n t, h u m a n s e n s o r y s k i l l s (co u p led w ith th e
i n s tr u m e n t- a id e d e x te n s io n s of s e n s itiv ity an d c a lib ra tio n ) p r e d o m in a te .
T h e o v e r a l l s u p p ly of s p a tia l d a ta now a v a ila b le h a s r e l i e d on th e s e n s in g
a b i lit y of tr a i n e d h u m a n s. T h e d e v ic e s th a t s e n s e p h e n o m e n a u n d e te c ta b le
b y h u m a n s a r e n o t in s u c h w id e s p re a d u s e (w ith th e p o s s ib le e x c e p tio n o f
th e c o m p a s s ); h ig h le v e ls of te c h n ic a l e x p e rt is e a r e r e q u i r e d to b u il d a n d
u s e s u c h d e v ic e s a s m a g n e to m e te rs , g e i g e r - c o u n te r s , i n f r a r e d - r a d i a t i o n
s e n s o r s , a n d r a d a r s c a n n e r s , an d s i m i l a r h ig h le v e ls of e x p e r t is e a r e
n e e d e d to u n d e r s ta n d t h e i r r e s u l t s .
T h e y a r e , h o w e v e r , b e in g r a p i d ly
d e v e lo p e d an d a r e c a p a b le of p r o d u c in g la r g e v o lu m e s o f d a ta f o r s u b s e q u e n t i n t e r p r e ta tio n .
D a ta m a y b e g a th e re d b y e i th e r " c o n ta c t" o r " r e m o te " s e n s in g m e th o d s .
C o n ta c t s e n s in g o c c u r s w h en th e s e n s in g d e v ic e is in c lo s e p r o x im ity to
th e it e m b e in g o b s e rv e d (a s in in te r v ie w s , g ro u n d s u r v e y s , m e te r e d
t r a f f i c c o u n ts , s u r f a c e m e te o ro lo g ic a l r e c o r d i n g s , o r h y d r o lo g ic a l s u r v e y s ) .
S a m p lin g of s o il, w a te r, r o c k , o r s i m i l a r s u b s ta n c e s f a l ls in to t h i s c a t e g o r y b e c a u s e th e s a m p le s a r e c o lle c te d b y a c o n ta c t p r o c e s s .
R e m o te
s e n s in g , o n th e o th e r h a n d , r e l i e s on a s e n s in g d e v ic e f a r f r o m t h e ite m ,
b e in g o b s e r v e d (a s in a ir b o r n e an d s a te lli te s e n s in g of th e e a r t h , u s e o f
l i d a r s a n d r a d a r s to m e a s u r e a tm o s p h e ric p r o p e r t ie s , e c h o -s o u n d in g o f
th e s e a f lo o r , s e is m i c m e a s u re m e n t of s u b s u rfa c e m a te r i a ls , o r s p e c t r a l
s e n s in g o f o b je c ts in s p a c e ).
O b v io u sly th e t e r m s " c lo s e p r o x im ity " a n d
" r e m o te " a r e s u b je c tiv e , an d r e p r e s e n t p o in ts on a co n tin u u m o f d is ta n c e
b e tw e e n th e it e m b e in g o b s e rv e d an d th e s e n s in g d e v ic e .
T h e c a te g o r ie s
a r e th u s n o t r ig o r o u s an d o n ly r e p r e s e n t a c o n v e n ie n t w ay t o th in k of
46
s e n s in g te c h n iq u e s .
I n s im i la r g e n e r a l t e r m s , w h e th e r th e s e n s in g
d e v ic e i s a c o n ta c t o r r e m o te o n e , th e f u r t h e r s te p of r e c o r d in g th e d a ta
m a y b e d o n e in c lo s e p ro x im ity to th e s e n s in g d e v ic e o r r e m o te ly , b y
m e a n s of s o m e f o r m o f c o m m u n ic a tio n c h a n n e l (as i s th e c a s e w ith m e te o r o lo g i c a l s o u n d in g b a llo o n s , a u to m a tic w e a th e r s ta tio n s , o r s u b s u r f a c e
th e r m i s t o r s ) .
T h e s e b r o a d c a te g o r ie s of te c h n iq u e s a r e s u m m a r iz e d
in th e d ia g r a m (F ig . 2 .5 ) .
REC O R D IN G PR O C E SS
R e m o te
C o n ta c t
In te r v ie w
W e a th e r b a llo o n
S e lf - r e c o r d in g
th e r m o m e te r
S u b su rfa c e
th e rm is to rs
A e ria l
p h o to g ra p h y
D ir e c t
tr a n s m is s i o n f r o m
s a te lli te s c a n n e r
C o n ta c t
SENSING
PROCESS
E x a m p le s
R e m o te
F ig . 2. 5.
T e le p h o n e
in te rv ie w
M eth o d s of s p a t i a l d a ta s e n s in g a n d re c o rd in g .
T h is b r i e f c o n s id e r a tio n of d a t a g a th e r in g m e th o d s im p lie s th a t th e s e c o n d
a r e a of te c h n o lo g y , t r a n s p o r t a ti o n a n d c o m m u n ic a tio n , is in v o lv e d in th e
o v e r a l l a b i lit y t o g a th e r d a ta .
S p a tia l d a ta , b y d e fin itio n , a r e g a th e r e d
f r o m v a r i o u s lo c a tio n s i n s p a c e .
If c o n ta c t s e n s in g i s e m p lo y e d , th e
s e n s in g d e v ic e m u s t b e tr a n s p o r t e d s o th a t it is in c lo s e p r o x im ity to th e
it e m o r c o n d itio n b e in g o b s e r v e d .
If th e d a ta a r e th e n r e m o te ly r e c o r d e d ,
a c o m m u n ic a tio n c h a n n e l i s r e q u i r e d .
If r e m o te s e n s in g is e m p lo y e d , th e
s e n s in g d e v ic e m u s t b e p o s itio n e d s o th a t th e ite m o r c o n d itio n of c o n c e r n
can b e o b serv ed .
I f o b s e r v a tio n s b e y o n d th e ra n g e of th e r e m o te s e n s in g
d e v ic e a r e n e e d e d , t h e d e v ic e m ust, b e tr a n s p o r t e d .
A g ain , if d a ta
r e c o r d i n g i s r e m o te f r o m t h e s e n s in g d e v ic e , a c o m m u n ic a tio n ch a n n e l
is r e q u i r e d .
T h e a v a ila b ility of s p a ti a l d a ta th u s r e s t s on tr a n s p o r t a ti o n
an d c o m m u n ic a tio n te c h n o lo g ie s .
e n o r m o u s ly in th e p a s t c e n tu r y .
T h e s e c a p a b ilitie s h av e ex p a n d ed
T h e y e a r s s in c e 1870 h av e s e e n th e
d e v e lo p m e n t of th e a u to m o b ile , d ir ig ib le , a i r c r a f t , te le p h o n e , r a d io ,
47
te le v is io n , h e lic o p te r , h o v e r c r a f t, r o c k e t , e a rt h s a te lli te , an d e a r l y
s p a c e s h ip .
g ro w th .
T e c h n o lo g y s e e m s to h av e fo llo w e d a p a t te r n o f a c c e le r a ti n g
T h e c e n t r a l th e m e of th i s th e s i s i s th e h an d lin g of s p a ti a l d a ta , but
c e r t a in l y th e a d v a n c e s in tr a n s p o r t a ti o n a n d c o m m u n ic a tio n te c h n o lo g ie s
a r e m a jo r in flu e n c e s on th e v o lu m e of s p a ti a l d a ta g a th e r e d .
W e m a y be
a c q u ir in g th e a b i lit y to g a th e r m o re d a ta th a n w e c a n h a n d le ; th i s p o in t
w ill b e d is c u s s e d in m o r e d e ta il in s u b se q u e n t c h a p te r s .
T h e t h i r d te c h n o lo g y w ith a d ir e c t in flu e n c e on th e a b ility to g a th e r d a ta
i s th a t o f d a ta re c o r d in g .
In th e e a r l i e r p a r t of th e c h a p te r th e e f f e c t o f
th e d im e n s io n s of th e r e c o r d i n g m e d iu m on th e d a ta f o r m a t w a s d is c u s s e d .
T h e o th e r e s s e n t i a l e le m e n t is th e e a s e of im p rin tin g a u n iq u e r e c o r d 1 o n
a s to r a g e m e d iu m a n d th e e a s e o f i t s s u b s e q u e n t r e t r i e v a l .
If a g ra p h ic o r a s y m b o lic la n g u a g e is u s e d to g e n e ra te a d e s c r i p tio n th a t
i s r e c o r d e d s o th a t it c a n b e r e a d v is u a lly , a " g ra p h ic r e c o r d " i s p ro d u c e d .
If e i t h e r la n g u a g e i s u s e d to g e n e ra te a d e s c r ip tio n th a t i s r e c o r d e d on a
s to r a g e m e d iu m f r o m w h ic h it ca n b e r e t r i e v e d b y o th e r h u m a n s e n s e s o r
b y m a c h in e m e th o d s , it i s t e r m e d a " n o n -g r a p h ic r e c o r d " .
It i s o b v io u s
th a t d a ta g a th e r in g i s in flu e n c e d n o t o n ly b y th e a b ility to s e n s e d a ta , b u t
a l s o b y th e su p p ly of d e v ic e s , h u m a n a n d m e c h a n ic a l, th a t p la c e th e o r i g i n a l r e c o r d in a s to r a g e m e d iu m .2
L e s s ob v io u s i s th e f a c t th a t th i s
a b ility i s d e p e n d e n t on th e a v a ila b ility o f a s u ita b le s to r a g e m e d iu m .
C o m p a re d w ith th e p r e s e n t - d a y su p p ly o f d a ta , few r e c o r d s w e r e g e n e ra te d
b e f o r e th e f i r s t p a r t of th e 18th c e n tu ry .
D e s p ite th e ad v e n t o f th e p r in tin g
p r e s s in 1588, p a p e r w a s n o t c h e a p ly p ro d u c e d u n til a p p r o x im a te ly 1750.3
T h e w id e s p r e a d a v a ila b ility o f p a p e r, h o w e v e r, a t a tim e of g ro w in g
l i t e r a c y , g ro w in g n e e d f o r d a ta , an d g ro w in g a b ility to o b s e r v e , s tr o n g ly
in flu e n c e d th e f o r m a t a n d v o lu m e of th e su b se q u e n t (an d p r e s e n t) su p p ly o f
1. T h e p r o c e s s of p la c in g a u n iq u e r e c o r d on a s to r a g e m e d iu m is h e r e
d if f e re n tia te d f r o m th e p r o c e s s o f r e p r o d u c in g c o p ie s of th a t r e c o r d . T h e
f i r s t a ff e c ts th e e a s e w ith w h ich d a ta a r e g a th e re d , a n d h e n c e w h ic h d a ta
e x i s t . T h e s e c o n d a f f e c ts th e d is s e m in a tio n of th e d a ta . T h e s e a r e c o n s id e r e d to b e p r im a r y a n d s e c o n d a r y in flu e n c e s in th e to ta l " a v a ila b ility "
o f d a ta . 2. T h e im p o r ta n t c o r o l la r y to th i s , th e a b ility to r e a d e i t h e r g ra p h ic
o r n o n - g ra p h ic r e c o r d s a n d to c o n v e rt one to th e o th e r , i s fu n d a m e n ta l to
s p a ti a l d a ta h a n d lin g a n d w ill b e d is c u s s e d in d e ta il in th e fo llo w in g c h a p te r s .
3. T h e f i r s t p a p e r - m a k in g m a c h in e w a s p ro d u c e d in 1798. T h e f i r s t p a p e r m a k in g m a c h in e in C a n a d a w a s b u ilt in 1803. W ood, a s o p p o se d to co tto n
o r r a g s , w a s f i r s t u s e d in 1720, w as f i r s t u s e d in a m i ll in 1800, a n d h ad
g e n e ra lly s u p p la n te d o th e r m a te r i a ls b y 1880.
48
d a ta .
T h e l a t e r p ro d u c tio n of p la s t ic f il m a n d th e c o a tin g o f m e ta l , g la s s ,
p a p e r, a n d p la s t ic f il m w ith s e n s itiv e l a y e r s a d d e d g r e a t ly to th e e a s e
w ith w h ich r e c o r d s co u ld b e g e n e ra te d .
T h e p e r i o d 1830-1890 saw th e
d e v e lo p m e n t of th e li g h t- s e n s iti v e c o a tin g a n d th e b i r t h o f p h o to g ra p h y a s
i t i s know n to d a y .
T h e im p a c t of th i s d e v e lo p m e n t on th e su p p ly o f a v a ila b le
d a ta i s d iffic u lt to o v e r e s t im a t e .
P r a c t i c a b l e p h o to g ra p h y c o in c id e d w ith
th e e a r l y d e v e lo p m e n t of th e a i r c r a f t .
A irb o rn e c a m e r a s h a v e b e e n u s e d
ro u tin e ly f o r o v e r 50 y e a r s f o r r e m o te s e n s in g a n d r e c o r d in g o f th e e a r t h 's
su rface.
T h e f i r s t C a n a d ia n a e r i a l p h o to g ra p h y (fo r f o r e s t s u rv e y ) w a s
in 1 9 2 1-24.
S in ce th a t ti m e , th e w h o le of C a n a d a ( o v e r 3 1 /2 m illio n
s q u a r e m ile s ) h a s b e e n p h o to g ra p h e d a t s c a l e s a t o r l a r g e r th a n 1:63, 360.
T h is im p lie s th a t t h e r e a r e s u b s ta n tia lly m o r e s q u a r e in c h e s o f o r ig in a l
p h o to g ra p h ic d o c u m e n ts a v a ila b le i n C a n a d a th a n t h e r e a r e o f to p o g r a p h ic
m ap s a t a ll s c a le s .
E v e n th o u g h s o p h is tic a te d in t e r p r e ta tio n is n e e d e d to
r e t r i e v e th e in h e r e n t d a ta f r o m th e p h o to g ra p h ic r e c o r d (u s u a lly a n o n co d e d im a g e ) , th e r e c o r d i n g m e d iu m (in c o n c e r t w ith s e n s in g d e v ic e s ,
t r a n s p o r t a ti o n te c h n iq u e s , g a th e r in g c o n s tr a in ts , and p e r c e iv e d n e e d s)
h a s h a d a d r a m a ti c e ffe c t on th e s p a t i a l d a ta a v a ila b le in C an a d a.
E q u a lly
p o te n t b u t s t i l l la te n t i s th e a b i lit y to s t o r e in f o rm a tio n on m e d ia w ith
m a g n e tic a lly s e n s itiv e c o a tin g s .
" M a g n e tic " w ir e , s te e l ta p e , a n d p la s t ic
ta p e b e c a m e a v a ila b le b e tw e e n 1889 a n d 1935.
T h e s e s to r a g e m e d ia , an d
d a ta c o d e d a s p a t te r n s of h o le s p u n c h e d i n p a p e r c a r d s a n d ta p e s , f o r m
th e b a s ic r e p o s it o r y of m a c h in e - r e a d a b le , n o n - g r a p h ic r e c o r d s o f s p a ti a l
d a ta a v a ila b le to d a y .
T h e a b i lit y of m a c h in e s to r e a d a n d r e p r o d u c e
s u c h r e c o r d s q u ic k ly , a n d s u b s e q u e n tly to e x a m in e a n d m a n ip u la te t h e i r
v a l u e s , i s a c e n tr a l c o n c e rn of t h i s t h e s i s a n d w ill b e e x a m in e d in th e
fo llo w in g c h a p te r s .
It i s s u ffic ie n t t o s a y a t th i s p o in t th a t d a ta r e c o r d in g
te c h n o lo g y h a s a s u b s ta n tia l im p a c t o n th e a b i lit y to g a th e r s p a ti a l d a ta
a n d on th e su p p ly of d a ta .
(b)
A v a ila b le r e s o u r c e s .
T h e c o n c e p t of p e r c e iv e d n e e d e x p r e s s e d ab o v e
in c lu d e d th e d e c is io n o f a c o u n try to a llo c a te r e s o u r c e s to d a ta g a th e rin g ;
to p a y f o r th e d a ta .
T o s o m e e x te n t, th e i n t e r n a l a v a ila b ility o f r e s o u r c e s
in a c o u n try h a s an e ffe c t on th e s u p p ly o f d a ta , b u t th e r e la tio n s h ip b etw e en
a v a ila b le fu n d s an d a v a ila b le s p a t i a l d a t a i s f a r f r o m c l e a r an d c e r t a in l y
n o t li n e a r .
49
In g e n e r a l, a d ev e lo p in g c o u n try , " p o o r " in t e r m s o f p e r c a p ita in c o m e ,
w ill n o t h a v e th e a b i lit y 1 to g a th e r a s m u c h d a ta a s a " r ic h " c o u n try .
In
th e f o r m e r , s tr o n g c o m p e titio n e x i s t s f o r i t s s c a r c e r e s o u r c e s o f tr a in e d
m a n p o w e r an d te c h n ic a l e x p e rt is e ; s o c ia l c o n s tr a in ts s u c h a s i l l i t e r a c y
m a y b e s ig n ific a n t; an d a d m in is tr a tiv e n e tw o rk s m a y b e r u d im e n ta r y a n d
u n a b le to g a th e r r e l ia b l e d a ta .
T h is l a t t e r p o in t is w o rth a m p lific a tio n .
T h e g o v e r n m e n ta l s o u r c e s of s p a ti a l d a ta c a n b e g e n e ra lly s u b d iv id e d in to
" a d m in is tr a tiv e " an d " s u r v e y " c a te g o r ie s .
T h e f o r m e r p ro d u c e d a ta a s
b y - p r o d u c ts o f th e a d m in is tr a tiv e a c tiv i tie s of g o v e rn m e n t (ta x r e t u r n s ,
b u ild in g p e r m i t s , v e h ic le r e g i s t r a t i o n s , h e a lth r e c o r d s , c r o p y ie ld s ,
an d s o fo rth ).
T h e l a t t e r a r e th e r e s u l t of s p e c if ic d e c is io n s to g a t h e r th e
d a ta ( c e n s u s , s o i l s u rv e y , g e o lo g ic a l s u r v e y , m e te o r o lo g ic a l s u r v e y , a n d
o th e r s ) .
In a d ev e lo p in g c o u n try th e a d m in is tr a tiv e s t r u c t u r e m a y g e n e ra te
l i t t l e a d m in is tr a tiv e d a ta , w h e re a s th e g r e a t e s t v o lu m e o f s p a ti a l d a ta
a v a ila b le in a n in d u s tr i a ll y a d v a n c e d n a tio n m a y c o m e f r o m s u c h s o u r c e s .
S u rv e y , on th e o th e r h a n d , r e q u i r e s l e s s w e ll e s ta b lis h e d g o v e rn m e n t
s t r u c t u r e s an d c a n ta k e m o re r a p i d a d v a n ta g e of a d v a n c e s in d a ta g a th e r in g
te c h n o lo g y .
A d v an ced d a ta g a th e rin g te c h n iq u e s , h o w e v e r, h a v e b e e n a
p ro d u c t of th e d e v e lo p e d c o u n tr ie s , an d th e y a r e u s u a lly f i r s t a p p lie d to
th e b e n e fit of s u c h c o u n tr ie s .
e x p o rte d .
N e v e r th e le s s , th e te c h n o lo g y c a n b e r e a d i ly
A v e r y c o m m o n f o r m of in t e r n a t io n a l a id is th e p r o v is io n of
s u r v e y e x p e rt is e ; th e a u th o r h a s ta k e n p a r t in s e v e r a l s u c h m is s io n s .
T h e v e r y p r o c e s s , h o w e v e r, u n d e r lin e s th e d if fe re n c e b e tw e e n a d m in is tr a tiv e an d s u r v e y d ata.
T h e ty p e o f r e c o r d s g e n e r a te d b y a d m in is tr a tiv e d a ta c a n b e r e a d i ly
e n v is a g e d ; t h e i r g e n e ra tio n i s d ir e c tl y r e l a t e d to th e s o p h is tic a tio n of th e
a d m in is tr a tiv e s tr u c t u r e in a c o u n try .
S u rv e y d a ta c a n e m p lo y a w id e
v a r i e t y o f g a th e rin g te c h n iq u e s a n d , a f t e r ta k in g th e p e r c e iv e d n e e d a n d
g a th e r in g c o n s tr a in ts in to a c c o u n t, th e a v a ila b ility of th e p ro d u c ts o f
s u r v e y s in an y one c o u n try d ep e n d s a s m u c h on p o li tic a l d e c is io n s , i n t e r n a tio n a l a lig n m e n ts , a n d in c id e n c e of w a r f a r e a s i t d o e s o n th e in t e r n a l
a v a ila b ility o f r e s o u r c e s .
R e s u ltin g D a ta C h a r a c te r i s t ic s
I t i s c l e a r f r o m th e ab o v e d is c u s s io n th a t s p a ti a l d a ta a r e g a th e r e d f o r a
1. A nd p ro b a b ly not th e s a m e n ee d .
50
v a r i e t y of r e a s o n s , b y v a r io u s m e th o d s , a n d i n th e f a c e o f v a r io u s d if f ic u l tie s .
T h e a p p ro a c h u s e d to g a th e r a s p e c if ic ty p e o f d a ta w ill o b v io u sly
a ffe c t th e n a t u r e of th e r e c o r d s p ro d u c e d a n d t h e i r r e l ia b i lit y .
T h e s e t of
c h o ic e s m a d e in a c o u n tr y d e te r m in e s th e c h a r a c t e r i s t i c s o f th e o v e r a ll
su p p ly of s p a t i a l d a ta to b e h a n d le d , a n d h e n c e th e ty p e s o f h a n d lin g
te c h n iq u e th a t w o u ld b e u s e fu l.
T h e u s e of d ata i s a ffe c te d b y th e c h a r a c t e r i s t i c s th a t c o n s tr a in t h e ir
v a lid ity an d th o s e th a t in flu e n c e t h e i r p h y s ic a l m a n ip u la tio n .
T h e ra n g e
of t h e s e c h a r a c t e r i s t i c s I s c o n s id e r e d b elo w .
V a lid ity c o n s tr a in ts .
A ll th e c o m p o n e n ts ( a t tr ib u t e s , s p a ti a l a n d te m p o r a l
c h a r a c t e r i s t i cs) of a d a ta e le m e n t c a n b e c o n s id e r e d to b e a t s o m e le v e l
o n a n im a g in a r y s c a l e o f v a lid ity (tru th ).
T h e y m a y not n e c e s s a r i l y b e a t
th e s a m e le v e l, a n d t h e i r a c tu a l r e l i a b i l i t y m a y o r m a y n o t b e a p p a re n t.
T h e f i r s t a s p e c t o f v a lid ity i s th e le v e l of e r r o r t h a t m a y h a v e b e e n i n t r o d u c e d b y th e p r o c e s s o f o b s e rv a tio n a n d m e a s u r e m e n t.
No h u m a n o r
in s tr u m e n ta l s e n s in g d e v ic e is p e rfe c t; th e e r r o r s p r o d u c e d m a y n o t b e
ra n d o m , a n d e n v ir o n m e n ta l c o n d itio n s m a y d if f e re n tia lly a ffe c t th e r e s u lt .
T h e s e n s in g p r o c e s s i t s e l f m a y a ffe c t th e s u b je c t; a n in q u ir y b y a g o v e r n m e n t a g e n t to a f a r m e r c o n c e rn in g h is c r o p d a m a g e , f o r e x a m p le , m a y
y ie ld d a t a e n t i r e l y d if f e re n t f r o m th o s e o b ta in e d b y a i r b o r n e s e n s in g of
th e s a m e in f o rm a tio n .
c a n o b v io u s ly b e l a r g e .
T h e ra n g e of s u c h e r r o r f o r a n y o n e o b s e r v a tio n
C a re fu l d e s ig n an d s c r e e n in g o f d a ta g a th e r in g
p r o c e s s e s c a n , h o w e v e r, r e d u c e th e o v e r a l l e r r o r of a d a ta s e t , an d w ith
a d e q u a te p r o c e d u r e s th e d e g re e of e r r o r in a d a t a s e t c a n b e e s tim a te d .
T h e s e c o n d a s p e c t o f v a lid ity c o n c e rn s th e n a t u r e of th e e n tity o r c o n d itio n
b e in g o b s e r v e d , a n d th e u s e to w h ic h i t s d e s c r ip tio n w ill b e p u t.
I t w as
m e n tio n e d a b o v e th a t o n ly w h en o b je c ts o r e v e n ts a r e c o u n ta b le b y th e
te c h n iq u e s o f o b s e r v a tio n a n d m e a s u r e m e n t u s e d c a n a c o m p le te o b s e r v a tio n b e m a d e .
I n a l l o th e r c a s e s , a n d in m a n y in s ta n c e s w h e r e th e s u b je c ts
a r e c o u n ta b le , a s a m p le i s ta k e n .
A n e x a m in a tio n of th e th e o r y a n d
p r a c t ic e of s a m p lin g i s o u ts id e th e s c o p e o f t h i s d is c u s s io n .
H o w e v e r, th e
w a y i n w h ic h th e s a m p le i s ta k e n a n d , in p a r t i c u l a r , th e f r e q u e n c y (d e n s ity
in s p a ti a l te r m s ) of th e s a m p le , c l e a r ly h a v e im p a c t o n th e c o m p le te n e s s
51
w ith w h ic h a n e n tity i s d e s c r ib e d .
T h e r e s u lt in g le v e l o f d e s c r ip tio n ,
c o u p le d w ith th e le v e l of e r r o r , m a y o r m a y n o t b e s ig n if ic a n t to th e
d e c is io n s to b e m a d e f r o m th e d a ta ; th e d a ta m a y o r m a y n o t b e v a lid in
te r m s of a s p e c ific u s e .
S e v e r a l b r o a d c a te g o r ie s of le v e l of d e s c r ip tio n c a n b e r e c o g n iz e d .
They
a r e e s s e n ti a ll y b a s e d on d if f e r e n c e s in s a m p lin g f re q u e n c y w ith r e s p e c t
to th e n a t u r e of th e e n t iti e s b e in g o b s e rv e d , a s o u tlin e d b elo w .
E x p l o r a to r y d a ta g a th e r in g r e s u l t s in g e n e ra l w id e - a r e a in v e n to r ie s b a s e d
on b r o a d c l a s s i f ic a t io n s .
U s in g n a t u r a l la n d s c a p e f e a t u r e s a s a n e x a m p le ,
m a jo r to p o g r a p h ic - c lim a tic z o n e s a r e id e n tifie d an d m a jo r r e l i e f u n its
a r e d e lim ite d .
T h e r e s u l t s a r e v a lid f o r a n in i tia l a s s e s s m e n t o f th e
p o te n tia l f o r c o m m e r c ia l d e v e lo p m e n t.
R e c o n n a is s a n c e d a ta g a th e r in g ty p ic a lly r e s u l t s in d a ta th a t c a n b e u s e d
to c o n f ir m th e e x is te n c e of p o s s ib le c o m m e r c ia l o p p o r tu n itie s a n d to
id e n tify a r e a s th a t w a r r a n t m o r e d e ta ile d s tu d y .
U sin g th e n a t u r a l la n d -
s c a p e e x a m p le a g a in , g r e a t s o il g r o u p s , m a jo r la n d f o r m s , a n d v e g e ta tio n
c o m m u n itie s a r e d if f e re n tia te d .
In te n s iv e d a ta g a th e r in g p ro v id e s in fo rm a tio n th a t u n d e r lie s p r e l im i n a r y
c a p a b ility s tu d ie s , c o s t b e n e fit a n a ly s is , a n d s o f o r th .
S o il s e r i e s , d e ta ile d
la n d f o r m s , a n d v e g e ta tio n a s s o c ia tio n s a r e id e n tif ie d in th e n a t u r a l
la n d s c a p e .
D e ta ile d d a ta g a th e r in g p ro v id e s in fo rm a tio n a t th e m a x im u m le v e l of
d e ta il n e e d e d to e s ta b lis h r e l ia b l e c o s t- b e n e f it r a t i o s o r to m a k e in p u t in to
m a n a g e m e n t d e c is io n s .
In th e n a t u r a l e n v iro n m e n t, p h a s e s o f s o il s e r i e s ,
la n d f o r m e le m e n ts , s lo p e u n its , v e g e ta tio n s p e c ie s d is tr ib u tio n , t r e e
c o u n ts , a n d s o f o r th , a r e id e n tifie d .
T h e le v e l of d e s c r ip tio n i s c l e a r l y r e l a t e d to th e in te n s ity o f d a ta g a th e r in g .
T h e a b o v e c a te g o r ie s a r e e s s e n ti a ll y s im p l is tic s u b d iv is io n s o f a co n tin u u m .
T h e p r e v a le n c e of d a ta s e t s th a t p ro v id e s p e c ific le v e ls of d e s c r ip tio n in
a n y c o u n try o b v io u s ly d e p e n d s on th e d a ta g a th e r in g c o n s tr a in ts , a n d th e
n e e d a n d te c h n iq u e s u s e d to o v e rc o m e th o s e c o n s tr a in ts .
In d iv id u a l d a ta
g a th e r in g te c h n iq u e s h a v e a r a n g e of a p p lic a b ility to c e r t a in le v e ls of
52
in t e n s ity of d a ta g a th e r in g , d e p e n d in g on t h e i r in h e re n t s e n s in g r e s o lu tio n
a n d th e e ff o rt n e e d e d to e m p lo y th e m .
T h e d iff ic u lty a r i s e s w h e n d a ta g a th e r e d a t a low le v e l o f s a m p lin g fre q u e n c y
o r in h e r e n tly h ig h le v e l o f e r r o r , o r b o th , a r e u s e d f o r d e c is io n s th a t
r e q u i r e m o r e d e ta ile d o r a c c u r a te d a ta .
F u r t h e r d if fic u ltie s a r i s e w h en
d a ta w ith v a r io u s s a m p lin g f r e q u e n c ie s a n d s a m p lin g d e s ig n s a r e c o m p a re d
o r c o m b in e d .
T h e s e a r e e l e m e n t a r y c o n c e r n s , b u t h a v e d ir e c t im p a c t on
th e u ti lit y of s u b s e q u e n t te c h n iq u e s of d a ta s to r a g e a n d m a n ip u la tio n .
A ll d a ta h a v e a r a t e o f d e c a y o f v a lid ity .
T h is m a y b e s p e c if ie d to s o m e
d e g r e e b y th e t e m p o r a l id e n tif i e r a tta c h e d to th e d a ta e le m e n t o r d a ta s e t.
It m a y n o t b e s p e c if ie d , b u t m a y b e u n d e r s to o d to b e a g e n e r a lly c o n s ta n t
r a t e of d e c a y ( a s f o r a p o p u la tio n c e n s u s ) .
O th e r d a ta , h o w e v e r, s u c h a s
p o li tic a l o p in io n , m a y b e s u b je c t to u n p re d ic ta b le c h a n g e s in th e r a t e of
d e c a y a n d t h e r e m a y b e no a p p r o p r i a te m e a s u r e of th i s " v o la tility " .
W h ile it w o u ld b e v a lu a b le , i t i s n o t w ith in th e s c o p e of th i s c h a p te r to
e x a m in e f u lly th e t h e o r y of d a t a c la s s if ic a tio n .
a n d " s e c o n d a r y " d a t a c a n b e id e n tifie d .
In g e n e r a l t e r m s , " p r im a r y "
P r i m a r y d a ta a r e d ir e c t r e c o r d s
( e ith e r c o n ta c t o r re m o te ) o f th e s e n s in g d e v ic e r e s p o n s e .
S e c o n d a ry
r e c o r d s a r e g e n e r a te d b y p r o c e s s e s s u c h a s g e n e ra liz a tio n , in te r p o la tio n ,
o r i n t e r p r e ta tio n o f p r i m a r y d a ta , u s u a lly w ith in s o m e s p e c if ie d r u le s of
c l a s s i f ic a t io n .
T h e d iffic u lty a r i s e s w h e n th e p r o c e s s e s a r e m ix e d to
p ro d u c e o n e s e c o n d a r y r e c o r d , a s th e y f r e q u e n tly a r e .
A s o il m a p , f o r
e x a m p le , c a n show s o i l ty p e s th a t, w ith in o n e s h e e t , m a y h a v e b e e n d e lim ite d
b y g e n e ra liz a tio n o f n u m e ro u s g ro u n d o b s e r v a tio n s , in te r p o la tio n b etw e en
s p a r s e g ro u n d o b s e r v a t io n s , o r in t e r p r e ta tio n of a e r i a l p h o to g ra p h ic im a g e s ,
o r a n y c o m b in a tio n o f t h e s e te c h n iq u e s .
O n th e o th e r h a n d , s u c h c l a s s i f i -
c a tio n m a y r e d u c e t h e e ffe c t o f e r r o r in in d iv id u a l d a ta an d g e n e ra te
s e c o n d a r y d a ta th a t a r e a d e q u a te f o r d e c is io n m a k in g b y th e u s e r .
As a
r e s u l t of th e s e p r o c e s s e s , h o w e v e r , t h e r e m a y n o t b e an a d e q u a te m e a s u r e
of th e in t e r n a l c o n s is te n c y a n d r e l i a b i l i t y o f a s e c o n d a r y d a ta s e t , an d i t s
v a lid ity f o r s p e c i f ic d e c is io n s m a y b e e f fe c tiv e ly o b s c u r e d .
T h e p ro b le m
i s th a t s e c o n d a r y r e c o r d s a r e n o t in fre q u e n tly th e o n ly " s o u r c e " d a ta
a v a ila b le .
53
P h y s i c a l h a n d lin g c h a r a c t e r i s t i c s .
T h e c h o ic e of te c h n iq u e s a n d le v e l o f
a c tiv ity f o r d a ta g a th e r in g in a c o u n tr y w ill d e te rm in e th e p h y s ic a l h a n d lin g
c h a r a c t e r i s t i c s of th e r e s u lt in g p r i m a r y d a ta .
T h e c h o ic e o f la n g u a g e
a n d r e c o r d i n g m e d iu m f o r d e s c r i p tio n s w ill d e te rm in e th e e a s e w ith w h ich
th e r e s u lt in g d a ta m a y b e r e a d .
T h e in te n s ity of d a ta g a th e r in g a n d th e
s iz e of th e c o u n try w ill d e te r m in e th e v o lu m e of d a ta to b e h a n d le d .
In th e e a r l y p a r t of th i s c h a p te r ( s e e " S p a tia l d a ta f o rm a t" ) it w a s s ta te d
th a t la n g u a g e s f o r d e s c r ib in g s p a ti a l d a ta a r e e x p r e s s e d e i th e r in a s y m b o lic f o r m ( a lp h a n u m e ric p lu s s p e c i a l s y m b o ls ) o r in a g r a p h ic f o r m .
W ith in th e l a t t e r i t i s p o s s ib le to d if f e re n tia te f u r t h e r b e tw e e n d ia g r a m s
a n d p i c t u r e s , d ia g r a m s b e in g g ra p h ic e x p r e s s io n s of a know n s p a ti a l
la n g u a g e , an d p ic tu r e s th e u n c o d e d r e c o r d s of im a g e s .
(It i s a n o p en
q u e s tio n w h e th e r th e l a t t e r i s a n e x p r e s s io n in an u n d e fin e d g ra p h ic
la n g u a g e . ) F o r p r a c t i c a l p u r p o s e s , th e m e d ia c u r r e n t ly u s e d f o r r e c o r d in g
s p a ti a l d a ta a r e a m e n a b le to th e p ro d u c tio n of e i th e r g ra p h ic o r n o n - g r a p h ic
re c o rd s.
T h e f i r s t a r e v is ib le m a r k s on d ocum ents, o r a r e p h o to g ra p h s
(on p a p e r , p la s t ic f ilm , o r , l e s s c o m m o n ly , g la s s o r m e ta l).
T he second
a r e m a c h in e - r e a d a b le m a r k s , s u c h a s p u n ch e d h o le s in p a p e r c a r d s o r ta p e s ,
o r m a g n e tic s ig n a ls on th e c o a tin g of ta p e s , d is k s , d r u m s , a n d s o f o r th .
T h e v a r io u s ty p e s of d a ta s e n s in g te n d to p ro d u c e s p e c if ic d a ta f o r m a ts ,
b u t t h e r e a r e e x c e p tio n s w ith in e a c h c a te g o ry .
H u m an s e n s in g an d
e x te n d e d h u m a n s e n s in g , f o r e x a m p le , g e n e r a lly p ro d u c e p r i m a r y d a ta
in a s y m b o lic f o r m a t.
in a g ra p h ic f o r m a t.
M any of th e s e a r e t r a n s f o r m e d to s e c o n d a r y d a ta
A n e x c e p tio n to th e g e n e ra l r u le , h o w e v e r, i s th e
s u r v e y o r w ho p lo ts th e m a tic b o u n d a rie s on m a p s a s h e w a lk s th e g ro u n d ,
o r w ho d r a w s s k e tc h e s of r o c k c o n ta c ts an d s o f o r th , th u s p r o d u c in g
d a ta d ir e c tl y in g r a p h ic f o r m a t.
S e lf - r e c o r d in g in s tr u m e n ts u s u a lly
p ro d u c e d a ta in g ra p h ic f o r m a t a s d ia g r a m s (g ra p h s o r tr a c in g s ) , b ut
s o m e now p ro d u c e d ig ita l d a ta (in s y m b o lic f o rm a t).
S e n sin g d e v ic e s th a t
tr a n s m i t in f o rm a tio n f o r r e m o te r e c o r d i n g u s u a lly s e n d d a ta in c o d e s (a
s y m b o lic f o r m a t) , w h ich m a y b e s u b s e q u e n tly tr a n s f o r m e d in to a n a n a lo g
o r d ig ita l f o r m ( g r a p h ic - f o r m a t d ia g r a m s o r s y m b o lic f o r m a t) .
g ra p h ic s e n s in g p ro d u c e s d a ta in p ic tu r e f o r m a t.
P h o to -
T h e m ix tu r e of d a ta
54
•
f o r m a ts p ro d u c e d o b v io u s ly d e p e n d s on th e d a ta g a th e r in g te c h n iq u e s
e m p lo y e d .
H o w e v e r, d a ta in a g ra p h ic fo r m a t ca n b e s to r e d o n ly in g r a p h ic
r e c o r d s , w h e r e a s d a ta in a s y m b o lic f o r m a t ca n b e s to r e d in e i th e r g ra p h ic
o r n o n - g ra p h ic r e c o r d s .
If d a ta in a g ra p h ic f o r m a t a r e to b e s to r e d o n
n o n - g r a p h ic r e c o r d s , th e y m u s t (in 1974) f i r s t b e c o n v e rte d to a s y m b o lic
f o r m a t.
T h e s e p o s s i b ili tie s a r e il l u s t r a t e d i n th e d ia g ra m . ( F ig . 2 . 6).
RECORD
FO R M A T
DATA
FORM AT
G RA PH IC
FO RM A T
D ia g ra m s
P ic tu re s
SYM BOLIC
FO R M A T
A lp h a n u m e ric
C o d es
S y m b o ls______
R E T R IE V A L
PO S S IB IL IT IE S
N O N -G R A P H IC
R EC O R D
M a g n e tic ta p e
M ach in e - a id e d
Punch c a rd
H u m an v is u a l
r e a d in g
G RAPH IC
R ECO RD
P aper
H u m an v is u a l
in t e r p r e ta tio n
P h o to
F ig . 2. 6.
R e la tio n s h ip s b e tw e e n d a ta f o r m a t, r e c o r d f o r m a t, a n d
r e t r i e v a l p o s s i b ili tie s .
T h e r e c o r d f o r m a t in t u r n d e t e r m i n e s th e f a c i l i t y w ith, which, th e d a ta c a n
be re trie v e d fo r u s e .
G ra p h ic r e c o r d s r e q u i r e hum an, v is u a l r e t r i e v a l ,
a n d p h o to g ra p h ic r e c o r d s m a y r e q u i r e a s o p h is tic a te d p r o c e s s o f i n t e r p r e ta tio n in v o lv in g h u m a n p a t te r n re c o g n itio n b e f o r e data, a r e id e n tif ie d .
N o n - g r a p h ic r e c o r d s allo w th e u s e of m a c h in e s to r e a d th e d a t a r a p id ly .
T h e s e c a p a b ilitie s o v e r la p so m e w h a t: a li m it e d n u m b e r o f m a c h in e s
( o p tic a l c h a r a c te r - r e c o g n it io n d e v ic e s ) c a n r e a d s y m b o ls o n g r a p h ic
r e c o r d s , a n d e q u a lly , a h u m a n c a n i n t e r p r e t a p a t te r n o f h o le s in a p u n c h
c a r d o r ta p e a n d s lo w ly d e te r m in e th e d a ta c o n te n t.
In t e r m s o f c u r r e n t
p r a c t i c e , h o w e v e r, t h e s e a r e u n im p o rta n t e x c ep tio n s..
In g e n e ra l, h u m a n r e t r i e v a l of d a ta f r o m g r a p h ic r e c o r d s i s a s lo w e r p r o c e s s th a n m a c h in e r e t r i e v a l of d a ta f r o m n o n - g r a p h ic r e c o r d s .
T h e e ffe c t
o f th i s o n th e u s e o f d a ta a n d th e r e l a ti v e c a p a b ility o f h u m a n a n d m a c h in e a id e d te c h n iq u e s f o r s u b s e q u e n t d a ta m a n ip u la tio n w ill h e th e s u b je c t o f
th e fo llo w in g c h a p te r s .
55
T h e v o lu m e of d a ta a v a ila b le i s p ro b a b ly th e m o s t im p o r ta n t in flu e n c e
on th e w a y th e d a ta a r e s u b s e q u e n tly h a n d le d .
In c o u n tr ie s w ith m a jo r
d a ta g a th e r in g c o n s tr a in ts a n d a low le v e l of d a ta g a th e r in g a b ility , th e
am o u n t of s p a t i a l d a ta g e n e ra te d i s lik e ly to b e w e ll w ith in th e e x is tin g
c a p a b ility f o r h a n d lin g b y h u m a n s o r m a c h in e s .
H o w e v e r, a lth o u g h th e
c o n s tr a in ts o n d a ta g a th e r in g a r e slow to c h a n g e , th e a b ility to g a th e r
d a ta i s i n c r e a s in g r a p id ly , a n d s o is th e v o lu m e of s p a ti a l d a ta .
The
v o lu m e o f d a t a g e n e ra te d in g ra p h ic , a s o p p o s e d to n o n - g r a p h ic , r e c o r d s ,
b e c o m e s p a r t i c u l a r l y s ig n if ic a n t b e c a u s e i t r e q u i r e s h u m a n r e t r i e v a l ,
w h ic h i s r e l a ti v e ly s lo w .
T h e n e e d to s u p p le m e n t h u m a n d a ta r e t r i e v a l
a n d m a n ip u la tio n w ith m a c h in e - a id e d p r o c e s s e s c l e a r ly d e p e n d s on th e
v o lu m e of d a ta g e n e ra te d in th e c o u n try c o n c e rn e d .
U se c o n s tr a in ts .
T h e n e e d f o r s p a ti a l d a ta m a y h a v e b e e n p e r c e iv e d ,
th e c o n s tr a in ts on g a th e r in g m a y h a v e b e e n o v e rc o m e b y v a r io u s te c h n iq u e s ,
a n d th e r e q u i r e d d a ta m a y a lr e a d y e x is t in s o m e f o r m a t.
F o r sev eral
r e a s o n s , h o w e v e r, t h e r e m a y b e c o n s tr a in ts on t h e i r a c tu a l u s e .
T h e c o n s tr a in t o n d a ta u s e im p o s e d b y t h e i r v a lid ity w a s m e n tio n e d ab o v e.
T h e le v e l of e r r o r , s a m p lin g d e s ig n , o r a g e of d a ta th a t a p p a r e n tly " e x is t"
m a y m a k e th e m u n s u ita b le f o r a p a r t ic u l a r u s e .
O th e r c o n s tr a in ts o n u s e c a n b e re c o g n iz e d .
V a rio u s ty p e s o f s p a ti a l d a ta
m a y b e r e q u i r e d f o r a s p e c ific p u r p o s e ; th e y m a y a l l e x is t, b u t m a y be
d is p e r s e d i n n u m e r o u s d e p a rtm e n ts , a t v a r io u s le v e ls o f g o v e rn m e n t, in
v a r io u s p a r t s of th e c o u n try .
T h e e ff o rt in v o lv e d in a s s e m b lin g th e
r e q u i r e d d a ta s e t s m a y e x c e e d a v a ila b le r e s o u r c e s , an d , in p r a c t i c a l
t e r m s , th e d a ta c a n n o t b e u s e d .
H igh d a ta v o lu m e c o m b in e d w ith low
r e a d in g c a p a b ility m a y h a v e th e s a m e e ffe c t.
If a d e c is io n h a s to b e m a d e ,
i t m a y n o t b e p o s s ib le f o r a s s e m b le d d a ta to b e r e a d , w ith a v a ila b le
r e s o u r c e s , in ti m e f o r t h e i r in fo rm a tio n c o n te n t to b e b ro u g h t to b e a r upon
th e d e c is io n .
A g a in , in p r a c t ic a l t e r m s , th e y a r e n o t a v a ila b le .
A m o r e p e r v a s iv e in flu e n c e on th e a v a ila b ility of d a ta is th e c o n s tr a in t o f
" c o n f id e n tia lity " .
In m a n y c o u n tr ie s , g o v e rn m e n t d e p a rtm e n ts g a th e r
d a ta th a t t h e r e a f t e r a r e le g a lly c o n fid e n tia l.
to c o n f id e n tia lity .
T h e r e a r e s e v e r a l d im e n s io n s
L e g a l c o n fid e n tia lity of c e r t a in ty p e s o f d a ta i s p r e s c r ib e d
56
to p r o te c t th e p r iv a c y of in d iv id u a ls (a s i n th e c a s e o f c e n s u s o r ta x a tio n
d a ta ), a n d s u c h d a ta m a y b e m a d e a v a ila b le o n ly in s u m m a r y f o r m .
O th e r
c o n f id e n tia lity c o n s tr a in ts a r e im p o s e d m e r e ly b e c a u s e th e d a ta g a th e r in g
a g e n c ie s w is h to c o n tr o l th e d a ta , b e c a u s e th e c o lle c tio n o r s to r a g e h av e
b e e n p o o r , o r b e c a u s e th e d a ta m a y b e c r i t i c a l o f th e in s titu tio n ’s p o lic ie s .
T h e r e a r e m a n y c a s e s of a p p a re n tly in n o c u o u s d a ta b e in g s u p p r e s s e d f o r
n o c l e a r l y d e fin e d r e a s o n .
T h e m i lit a r y , in p a r t i c u l a r , h a v e a s tr o n g
in flu e n c e on d a ta a v a ila b ility i n s o m e c o u n tr ie s .
T h e ir a ttitu d e s te m s
f r o m a d e s i r e to p re v e n t d a ta f r o m r e a c h in g th e " e n e m y " a n d to a v o id
r e v e a lin g t h e i r ow n d a ta g a th e r in g c a p a b ility .
In N o rth A m e r ic a , f o r
e x a m p le , i t i s s p e c u la te d th a t a t l e a s t 50 e a r t h s a t e l l i t e s o c c u p y in g v a r io u s
m o b ile a n d s ta t io n a r y o r b it s a r e m o n ito rin g c o n d itio n s o n th e e a r t h 's
su rfa c e .
Som e of th e m a r e r e p u te d to o p e r a te s e n s o r s w ith h ig h le v e ls
o f r e s o lu tio n .
T h e o n ly s a t e l l i t e s p ro d u c in g w id e ly a v a ila b le s p a t i a l d a ta
a r e th e T IR O S a n d E R T S s a t e l l i t e s , a n d th e y c a r r y s e n s o r s w ith o n ly
lo w - le v e l re s o lu tio n .
O ne c a n a r g u e th a t i t w a s a lw a y s th u s a n d th a t th e s e c o n s tr a in ts a r e a
fu n c tio n of th e n a t u r e of m a n k in d .
I t m u s t, h o w e v e r, b e p o in te d o u t th a t
s u c h c o n s tr a in ts a r e a f u r t h e r v a r i a b le th a t in flu e n c e s th e s u p p ly a n d
a v a ila b ility of d a ta in a n y p a r t i c u l a r c o u n try .
R e s u ltin g S p a tia l D a ta S upply a n d A v a ila b ility
T h e v a r i a b le s th a t d e te r m in e s p a ti a l d a ta a v a ila b ility d e s c r ib e d ab o v e a r e
c l e a r l y in te r d e p e n d e n t.
T h e a v a ila b ility o f a p a r t ic u l a r d a ta s e t in one
c o u n try i s th e r e s u l t o f a s e r i e s o f c h o ic e s m a d e w ith r e s p e c t to e a c h o f
th e v a r i a b le s .
T h e s e r i e s o f c h o ic e s c a n b e th o u g h t of a s a p a th tr a c e d
th ro u g h th e v a r io u s c o n s tr a in ts a n d c a p a b ilitie s .
A g e o lo g ic a l s u r v e y in C a n a d a , f o r e x a m p le , w ould r e p r e s e n t th e p e r c e iv e d
n e e d f o r d a ta b y th e c e n tr a l g o v e rn m e n t o f a c o u n try w ith a r e l a ti v e ly h ig h
le v e l of e c o n o m ic d e v e lo p m e n t.
T h e s iz e of th e c o u n try f o r m s a c o n s tr a in t;
a l s o , th e c lim a te is g e n e ra lly c o ld a n d o v e r a l l t r a f f i c a b i lit y is b a d .
w o u ld b e l i t t l e p o litic a l o r s o c ia l o b je c tio n t o th e s u r v e y .
T h e re
A b a la n c e d c o m -
b in a tio n of h u m a n a n d e x te n d e d h u m a n s e n s in g d e v ic e s c o u ld b e e m p lo y e d ,
t r a n s p o r t a ti o n of th e s e c o u ld b e a id e d b y a i r c r a f t , h e lic o p te r , a n d
57
a u to m o b ile , a n d b o th r e m o te a n d c o n ta c t s e n s in g w o u ld b e e m p lo y e d ,
w ith c o n ta c t r e c o r d i n g in e a c h c a s e .
T h e r e c o r d in g m e d ia w o u ld in c lu d e
b o th p a p e r a n d p h o to g ra p h s , a n d th e s u r v e y w o u ld b e u n d e r ta k e n b y a
s u r v e y a g e n c y u s in g t r a i n e d r e s id e n ts .
T h e d a ta c h a r a c t e r i s t i c s w ould
r e s u l t f r o m a s u b s ta n tia l a m o u n t of r e c o n n a is s a n c e d a ta g a th e r in g , a
f a i r l y low le v e l of e r r o r in p r im a r y o b s e r v a tio n , a n d a m e d iu m le v e l o f
e r r o r in s e c o n d a r y r e c o r d s due t o th e r e l a ti v e ly low le v e l o f in te n s ity o f
th e d a ta g a th e r in g .
T h e r e s u lt in g d a ta w o u ld in c lu d e l a r g e n u m b e r s of
a n n o ta te d a i r p h o to g ra p h s , p lu s d o c u m e n te d f ie ld n o te s a s p r im a r y d a ta ,
a n d a r e l a ti v e ly few s m a l l - s c a l e m a p s a s s e c o n d a r y " s o u r c e " d a ta .
d a ta w o u ld b e a v a ila b le f o r g e n e ra l u s e on r e q u e s t .
A ll
T h e m a p s w o u ld be
a v a ila b le a s a p r in t e d m a p s e r i e s .
A s a c o n t r a s t, le t u s c o n s id e r th e in flu e n c e s on a r e c e n t g e o lo g ic a l
s u r v e y i n a c o u n try s u c h a s S outh V ie tn a m .
T h e c o u n tr y h a s a low le v e l
o f e c o n o m ic d e v e lo p m e n t, a n d th e s u r v e y w o u ld b e u n d e r ta k e n p r im a r il y
f o r m i lit a r y p u r p o s e s b y a c e n tr a l g o v e rn m e n t.
I t is a m e d iu m - to - s m a l l
c o u n try w ith a h o t c l im a te , e x te n s iv e v e g e ta tio n c o v e r, a n d p o o r o v e r a l l
tr a f fi c a b i lit y .
P o l i t i c a l c o n s tr a in ts m a y b e lo w , b u t s o c ia l c o n s tr a in ts
o n a s u r v e y m a y b e h ig h .
T h e te c h n iq u e u s e d w o u ld b e a lm o s t e x c lu s iv e ly
p h o to g ra p h ic , a i r b o r n e , r e m o te s e n s in g w ith c o n ta c t r e c o r d i n g r e s u lt in g
in p h o to g ra p h ic r e c o r d s .
T h e s u r v e y w o u ld b e u n d e r ta k e n w ith te c h n olo g y
d e r iv e d f r o m o u ts id e th e c o u n try a n d c a r r i e d o u t b y n o n r e s id e n t te c h n ic ia n s
w ith l i t t l e e x p e rie n c e o f th e g ro u n d c o n d itio n s in th e c o u n try .
T h e r e s u lt in g
d a ta w ould p ro b a b ly in c lu d e a m e d iu m am o u n t p ro v id e d b y r e c o n n a is s a n c e
s u r v e y , a n d s o m e a t a h ig h e r le v e l, of d a ta g a th e r in g in te n s ity f r o m s i t e s
of s t r a t e g i c im p o rta n c e .
A m e d iu m -to -h ig h le v e l of e r r o r c o u ld b e e x p e c te d
in p r i m a r y an d s e c o n d a r y r e c o r d s .
T h e r e s u lt in g d a ta w o u ld in c lu d e la r g e
n u m b e r s of a n n o ta te d a i r p h o to g ra p h s , few o r no s u p p o r tin g f ie ld n o te s ,
a n d a m e d iu m -to -h ig h n u m b e r o f m e d iu m - s c a le m a p s a s s e c o n d a r y " s o u r c e "
d a ta .
T h e r e m ig h t b e s e v e r e c o n s tr a in ts on th e a v a ila b ility o f th e d a ta f o r
g e n e ra l u s e .
A t h i r d e x a m p le m ig h t b e a g e o lo g ic a l s u r v e y of a c o u n tr y s i m i l a r to G re a t
B r ita in .
T h e c o u n try i s a s s u m e d to h a v e h a d a p e r c e iv e d n e e d f o r g e o lo -
g ic a l s u r v e y f o r c o m m e r c ia l p u r p o s e s d u r in g th e in d u s tr i a l re v o lu tio n , an d
58
i t i s u n d e r a s tr o n g c e n tr a l g o v e rn m e n t, w ith no d ir e c t m i lit a r y in flu e n c e .
T h e c o u n try i s s m a l l, h a s a te m p e r a t e c lim a te , p r e s e n t s good o v e r a l l
t r a f f i c a b i lit y , an d e x h ib its no s ig n ific a n t p o li tic a l o r s o c ia l o b je c tio n s
to th e s u r v e y .
T h e e a r l y in i tia l p e r c e iv e d n e e d f o r th e s u r v e y , c o u p le d
w ith th e low le v e l of c o n s tr a in ts , w o u ld allow h u m a n c o n ta c t s e n s in g a n d
r e c o r d in g , b y tr a in e d r e s id e n ts e m p lo y e d b y a s u r v e y a g e n c y .
The
r e s u lt in g d a ta w o u ld r e p r e s e n t a h ig h le v e l of d a ta g a th e r in g in te n s ity , a
low le v e l o f e r r o r , a n d th e p ro d u c tio n of a m e d iu m q u a n tity of l a r g e - s c a l e
p a p e r m a p s a s " s o u r c e " d o c u m e n ts .
F ie l d d o c u m e n ta tio n w o u ld e x i s t ,
b u t w o u ld n o t b e a v a ila b le due to g a th e rin g - a g e n c y c o n s tr a in ts .
T h e th r e e e x a m p le s i l l u s t r a t e ty p i c a l d if f e re n c e s in th e d a ta c h a r a c t e r i s t i c s ,
r e c o r d c h a r a c t e r i s t i c s , a n d a v a ila b ility of. d a ta th a t e x is t f o r o n e ty p e o f
d a ta in d if fe re n t c o u n tr ie s .
T h is v a r i a b il ity o c c u r s n o t o n ly b e tw e e n
c o u n t r ie s , b u t b e tw e e n p a r t s of c o u n tr ie s , a n d b e tw e e n d a ta ty p e s w ith in
o ne c o u n try .
SUMMARY
T h is c h a p te r h a s b r ie f ly e x a m in e d th e c h a r a c t e r i s t i c s o f lo c a tio n - s p e c if ic
d a ta .
T h e c o n c e p ts th a t u n d e r lie s p a ti a l d e s c r ip tio n w e r e c o n s id e r e d , a n d
th e in flu e n c e of th e s to r a g e m e d ia on s p a ti a l d a ta fo r m a t w a s sh o w n .
The
m a in ty p e s o f lo c a tio n id e n tif ie r c u r r e n t ly u s e d w e r e id e n tifie d , th e f a c t o r s
th a t in flu e n c e th e o v e r a l l su p p ly a n d a v a ila b ility of lo c a tio n - s p e c if ic d a ta
w e re e x a m in e d , a n d th e r a n g e of v a r ia tio n th a t e x i s t s w a s i l lu s tr a t e d .
O nce a s u p p ly of s p a ti a l d a ta h a s b e e n o b ta in e d , th e n e e d e x i s t s to s t o r e ,
r e a d , a n d a n a ly s e th e m if t h e i r in fo rm a tio n c o n te n t is to b e a p p lie d to
d e c is io n s .
T h e n ex t p a r t of th i s th e s i s w ill e x a m in e th e s ta t e o f d e v e lo p -
m e n t of s p a ti a l d a ta h a n d lin g te c h n iq u e s .
T h e u s e fu ln e s s o f s u c h te c h n iq u e s
d e p e n d s to a c o n s id e ra b le e x te n t on th e su p p ly of d a ta th a t m u s t b e h a n d le d ,
a n d it h a s b e e n show n th a t th is m a y v a r y s u b s ta n tia lly b etw e en c o u n tr ie s .
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C H A P T E R 3 - MANUAL TECH N IQ U E S F O R H ANDLING M A P P E D AND
O T H E R L O C A T IO N -S P E C IF IC DATA
F o r th e p u r p o s e s o f th i s d is c u s s io n , m a n u a l te c h n iq u e s f o r h a n d lin g m a p p e d
a n d o th e r lo c a ti o n - s p e c if ic d a ta a r e ta k e n to b e th o s e a c c o m p lis h e d byh u m a n s k ill, a id e d b y d ra f tin g a n d p h o to g ra p h ic e q u ip m e n t b u t n o t b y
e l e c tr o n i c d a ta p r o c e s s in g eq u ip m e n t.
In g e n e ra l, th e y f o r m th e b a s ic
m e th o d o lo g y o f lo n g - e s ta b lis h e d c a rto g r a p h ic p r a c t ic e .
u s e d to c a r r y out m o s t s p a ti a l d a ta h a n d lin g ta s k s .
T hey a r e s till
A ls o , v ie w e d in th e
t o t a l c o n te x t o f d a ta h a n d lin g r a t h e r th a n o n ly a s " tr a d itio n a l c a r to g r a p h ic
p r a c t i c e " , th e v a r io u s m a n u a l m e th o d s f o r m a s e r i e s of b e n c h m a r k s o f
t r a d iti o n a l c a p a b ility a g a in s t w h ic h m a c h in e m e th o d s m u s t b e ju d g e d .
D e s c r ip tio n s of m a n u a l te c h n iq u e s in th i s c h a p te r w il l fo c u s o n t h e i r
tim in g an d e ffic ie n c y .
V iew ed in th e c o n te x t of d a ta h a n d lin g , a m a p is a lo c a tio n - s p e c if ic d a ta
" f il e " in w h ic h e a r t h d a ta a r e g a th e r e d , o r d e r e d , an d r e c o r d e d in a w ay
th a t p r e s e r v e s th e m e a s u r e s of t h e i r s p a ti a l a t tr ib u t e s an d d is tr ib u tio n .
T h e f i l e 's s t r u c t u r e p r e s u p p o s e s s o m e c o n c e p tu a l m o d e l of th e s p a c e
o c c u p ie d b y th e g lo b e , a n d s u ita b le u n its f o r i t s m e a s u r e m e n t.
The
E u c lid e a n m o d e l, w ith d e g r e e s of la titu d e a n d lo n g itu d e a s u n its of m e a s u r e m e n t, i s th e one w id e ly a c c e p te d .
I t s a p p r o p r i a te n e s s , u tility , o r v a lid ity
w ill n o t b e c a lle d in to q u e s tio n in th i s c h a p te r .
T h e c l a s s i c t a s k of g e o d e tic a n d to p o g ra p h ic s u rv e y in g i s to r e c o r d in s u c h
a f il e th e c o n fig u ra tio n of th e e a r t h 's s u r f a c e a n d a v e r y li m it e d s e t o f i t s
fe a tu re s.
T h e lo c a tio n o f a s e r i e s o f id e n tifia b le p o in ts o n th e g ro u n d i s
e s ta b lis h e d b y m u ltip le m e a s u r e m e n ts b e tw e e n th e p o in ts , a n d b e tw e e n th e m
a n d e x t r a t e r r e s t r i a l b o d ie s .
P la n e g r a p h ic r e p r e s e n t a ti o n s (m ap s) o f th e
c u r v e d s u r f a c e of th e e a r t h a r e p ro d u c e d b y m a th e m a tic a l tr a n s f o r m a tio n s
(m ap p r o je c tio n s ) .
E s ta b lis h e d p o in ts a r e " file d " on th e m a p s a c c o r d in g
to t h e i r m e a s u r e d r e l a ti v e p o s itio n s .
E le m e n ts o f th e m a tic d a ta a r e
lo c a te d b y o b s e rv in g o r m e a s u r in g t h e i r r e l a ti o n s h i p w ith e a s i ly id e n tif ie d
f e a t u r e s a l r e a d y s to r e d in th e s p a ti a l f il e , a n d a r e r e c o r d e d b y in s e r t in g
t h e m in to th e a p p r o p r ia te p la c e in th e f il e , th a t i s , b y p lo ttin g th e o b s e r v a tio n s on a m a p .
60
T h e u s e o f a e r i a l p h o to g ra p h s a s th e s o u r c e o f b o th to p o g r a p h ic a l in f o r m a tio n (p h o to g ra m m e try ) an d th e m a tic d a ta (p h o to -in te rp r e ta tio n ) fo llo w s th e
s a m e g e n e r a l p r o c e d u r e a s f o r g ro u n d s u r v e y .
T h e m a in d if f e re n c e i s
th a t th e r e la tio n s h ip s b e tw e e n o b je c ts o r th e r e la tio n s h ip s b e tw e e n th e m a tic
d a ta a n d to p o g ra p h ic o b je c ts a r e o b s e rv e d a n d m e a s u r e d o n p h o to g ra p h s ,
a n d o n ly a few o b s e r v a tio n s on th e g ro u n d a r e n e c e s s a r y .
B e f o re 1960, th e o n ly f o r m of s to r a g e f o r s p a ti a l d a ta w a s g r a p h ic (as
m a p s ) , a n d i t s p r e c i s io n v a r ie d .
D ata c o m p a c tio n w a s a tte m p te d b y u s e
o f s y m b o ls , a n d d a ta s e p a r a tio n a n d id e n tific a tio n w e r e f r e q u e n tly a id e d
b y c o lo u r s .
R e t r ie v a l of d a ta f r o m th e f il e w a s m a in ly m a n u a l.
T h e se
m a n u a l r e t r i e v a l p r o c e d u r e s h a v e n o t c h a n g ed s u b s ta n tia lly in th e p a s t 30
y e a rs .
T h e s t a r t i n g p o in t o f m a n u a l p r o c e d u r e s f o r h a n d lin g g r a p h ic a lly s t o r e d d a ta
i s th u s th e m a p it s e lf .
T h e e ffic ie n c y of th e m a p a s a s o u r c e o f d a ta f r o m
w h ic h u s e fu l in fo rm a tio n h a s to b e e x tr a c te d , an d th e te c h n iq u e s f o r
e x t r a c ti n g i t , n e e d to b e e x a m in e d .
f a l l in to t h r e e g e n e r a l c a te g o r ie s .
Such s p a tia l d a ta h a n d lin g te c h n iq u e s
T h e f i r s t i s " im a g e m a n ip u la tio n " ,
w h ic h c h a n g e s th e a r e a o f th e g r a p h ic m a t e r i a l on w h ich d a ta a r e to b e
d is p la y e d .
T h is c a te g o ry in c lu d e s c h a n g e s of s c a l e , c o r r e c tio n o f d i s t o r -
tio n s in th e o r ig in a l m a te r i a l, a n d c h a n g e s of m a p p ro je c tio n .
T he second
in v o lv e s th e "g ro u p in g " of d a ta o r s e t s of d a ta a n d th e p ro d u c tio n o f a new
o r a m e n d e d r e c o r d p r i o r to d a ta e x tr a c tio n .
It in c lu d e s s u c h p r o c e d u r e s
a s c e n tr o id a llo c a tio n , m e r g in g an d d is s o lv in g of d a ta , an d g e n e ra liz a tio n .
B o th im a g e m a n ip u la tio n a n d g ro u p in g a r e b r o a d c a te g o r ie s o f d a ta h a n d lin g
te c h n iq u e s th a t a f fe c t th e r e t r ie v a b i lit y of d a ta f r o m th e g ra p h ic f ile .
A lthough t h e r e i s in e v ita b le o v e r la p p in g b e tw e e n th e tw o g r o u p s , th e f o r m e r
i s p r i m a r i l y c o n c e r n e d w ith c h a n g e s in th e g ra p h ic im a g e o f th e d a ta an d
th e l a t t e r i s c o n c e rn e d w ith c h a n g e s in th e s u b s ta n tiv e v a lu e s of th e d a ta
e le m e n ts .
T h e t h i r d g e n e r a l c a te g o r y i s th e p r o c e s s of " d a ta e x tr a c tio n "
i t s e l f , a n d in c lu d e s v is u a l in s p e c tio n a n d e s tim a tio n , s e le c te d e x tr a c tio n ,
a n d m e a s u r e m e n t.
T h e s to r a g e m e d iu m a ff e c ts a l l s u b se q u e n t p r o c e s s e s of d a ta h a n d lin g .
m a y v a r y f r o m p a p e r of v a r io u s q u a litie s an d c o n d itio n s to m o r e s ta b le
It
61
m a te r i a ls s u c h a s p a p e r b o n d ed to m e ta l o r p la s t ic film s (o p aq u e, t r a n s
lu c e n t, o r c l e a r ) , e m u ls io n s on p la s t ic o r g la s s , o r d ir e c t e n g ra v in g s on
m e ta l.
E a c h of th e s e m e d ia h a s s o m e w h a t d iff e re n t p h y s ic a l c h a r a c t e r i s t i c s ,
a n d m a y b e u s e d a t v a r io u s s ta g e s of m a p p ro d u c tio n . A s a n e n d p ro d u c t,
h o w e v e r, t h e r e a r e tw o p re d o m in a n t ty p e s of g ra p h ic d a ta s to r a g e : th e
m a p th a t i s c o l o u r - p r i n te d on p a p e r, a n d th e m a p d ra w n in a s in g le to n e
o n p la s tic f ilm .
T h e s e tw o ty p e s of g r a p h ic s to r a g e e n c o m p a s s th e o v e r -
w h e lm in g a m o u n t of s p a ti a l d a ta in g r a p h ic f o rm .
IM A G E M A N IPU L A T IO N
Im a g e m a n ip u la tio n i s th e c o n tro lle d s tr e t c h in g o r s h rin k in g o f a g iv e n
im a g e .
It i s a c h ie v e d b y v a r io u s m e a n s an d u s e d to a ffe c t th e r e t r i e v a
b il ity of th e g r a p h ic in fo rm a tio n .
S im p le ch a n g e of s c a le is a r e s u l t of
e q u a l a n d o rth o g o n a l s tr e t c h in g o r s h rin k in g .
A fte r r e d u c tio n o f th e im a g e ,
in fo rm a tio n r e t r i e v a l i s a ffe c te d b y f a c t o r s of v is u a l a c u ity , a n d a f t e r
e n la r g e m e n t b y th e f a c t o r of v is u a l s c a n n in g ( re d u c tio n o f s y n o p s is ).
R e c til in e a r d i s t o r t i o n s 1 in a g iv e n im a g e c a n b e e lim in a te d b y li n e a r
s tr e t c h in g o r s h r in k in g a lo n g one o r m o re a x e s (not n e c e s s a r i l y e q u a l o r
o rth o g o n a l).
N o n lin e a r d is to r tio n e lim in a tio n i s a n o n lin e a r v e r s io n of th e
la tte r p ro c e ss.
M ap p r o je c tio n ch a n g e i s e s s e n ti a ll y a c o n tr o lle d f o r m of
l i n e a r o r , m o r e o fte n , n o n lin e a r s tr e t c h in g o r s h rin k in g w h e r e th e p r o p e r t i e s of th e d is to r t io n in th e r e s u lt in g d is p la y m u s t b e know n.
T h e su b se q u e n t
r e t r i e v a b i l i t y of in f o rm a tio n m a y b e a ffe c te d b y b o th of th e f a c t o r s r e l a ti n g
t o s c a l e c h a n g e n o te d ab o v e , an d a ls o b y th e ch a n g e in d is tr ib u tio n o f s u b
s ta n tiv e in fo rm a tio n .
L i n e a r s tr e t c h in g o r s h rin k in g of an im a g e c a n b e a c h ie v e d in s e v e r a l w ay s.
T h e s im p l e s t b u t m o s t la b o r io u s is th e p o in t- b y -p o in t t r a n s f e r o f d a ta b y
h a n d a n d e y e f r o m th e s o u r c e m a t e r i a l to th e new e n la rg e d o r r e d u c e d
f o r m a t.
M o re co m m o n i s th e u s e of a " p a n to g ra p h " , a d e v ic e th a t m e c h a n i
c a lly lin k s a d ra w in g d e v ic e to a c u r s o r w ith w h ich th e o r ig in a l im a g e is
tra c e d .
T h e lin k a g e i s a d ju s ta b le s o th a t th e im a g e b e in g d ra w n c a n b e
l a r g e r o r s m a l l e r th a n th e o rig in a l.
O p tic a l m e th o d s in v o lv e p r o je c tio n
o f th e s o u r c e m a t e r i a l on to a s u ita b ly a lig n e d p la n e s u r f a c e , w h e r e th e new
im a g e i s r e c o r d e d b y tr a c i n g o r b y u s in g p h o to s e n s itiv e m a te r i a l.
The use
1 . E lim in a tio n o f r e c t i l i n e a r d is to r tio n in th i s s e n s e d o e s n o t m e a n c o n v e r s io n to th e a ll - c u r v e d , s p h e r ic a l s u r f a c e b u t r e f e r s o n ly to d is to r tio n
i n c o m p a ris o n w ith a s ta n d a r d th a t h a s n o t u n d e rg o n e d im e n s io n a l ch an g e.
62
o f a n e p id ia s c o p e o r s im p le s lid e p r o je c to r to s h in e im a g e s on a f la t
s u r f a c e f a l ls in to th i s c a te g o ry .
T h e in h e re n t d is to r tio n s o f s u c h s im p le
o p tic a l s y s t e m s c a n b e re m o v e d b y th e u s e of h ig h - p r e c is io n c o p y c a m e r a s ,
s ta b le b a s e m a t e r i a l s , v a c u u m f r a m e s , a n d s o f o rth .
T h e e n la r g e m e n t o r
re d u c tio n of l e t t e r s , n u m b e r s , an d s y m b o ls d o e s in tro d u c e p r o b le m s of
a e s t h e ti c s a n d le g ib ility , a n d i f th e s e b e c o m e s e v e r e , th e te x tu a l in f o r m a tio n m a y h a v e to b e re m o v e d a n d r e i n tr o d u c e d a f t e r a lte r a tio n .
C o lo u rs
c a n b e t r a n s f e r r e d f r o m th e o r ig in a ls b y u s e o f c o lo u r p h o to g ra p h y o r
c o lo u r s e p a r a t io n a n d a f u r t h e r p r in t in g p r o c e s s .
N o n lin e a r s tr e t c h in g o r
s h r in k in g of a n im a g e c a n n o t, h o w e v e r, b e a c h ie v e d w ith s u c h s im p le
o p tic a l o r m e c h a n ic a l s y s t e m s ; it r e q u i r e s q u ite e x p e n siv e o p tic a l p r o c e s s e s
in w h ic h in d iv id u a l l e n s e s a r e p ro d u c e d f o r s p e c if ic n o n lin e a r c o r r e c tio n s ,
o r e l s e th e s im p l e r b u t s lo w e r p r o c e s s o f p o in t-b y -p o in t t r a n s f e r .
S c a le C hange
T h e c u r r e n t m a n u a l p r o c e s s e s of s c a l e ch a n g e th u s in v o lv e e i th e r r e l a ti v e ly
s im p le p r o c e d u r e s w ith in h e re n t in a c c u r a c ie s (in t e r m s o f h u m a n e r r o r , in
o p tic a l s y s t e m s , a n d in tr a c in g p r o c e s s e s th a t m e c h a n ic a lly tr a n s m i t o r
f ix th e im a g e ), o r th e y e m p lo y r e l a ti v e ly s o p h is tic a te d , h ig h - p r e c is io n
o p tic a l e q u ip m e n t, e x p e rie n c e d te c h n ic ia n s , an d n o t in e x p e n s iv e p h o to s e n s itiv e m a t e r i a l s a n d c h e m ic a ls .
T o ch a n g e th e s c a l e o f a 2 0 - in . x 3 0 -in .
m a p s h e e t m a n u a lly w ould n o r m a lly ta k e b e tw e e n 1 a n d 10 h o u r s o f
e x p e rie n c e d la b o u r , d e p e n d in g o n th e d a t a c o n te n t of th e m ap s h e e t c o n c e rn e d .
D is to rtio n E lim in a tio n
A lthough d is to r t io n e lim in a tio n i s u s u a lly p e r f o r m e d w h en d a ta a r e in s e r t e d
in to a s p a ti a l f il e r a t h e r th a n w h ile th e y a r e in t h e i r s to r e d f o r m , te c h n iq u e s
in v o lv in g th e l a t t e r i l l u s t r a t e th e d if fic u ltie s of m a n u a l p r o c e s s e s .
N on-
s ta b l e m a t e r i a l s u c h a s p a p e r m a y o c c a s io n a lly b e u s e d f o r s to r a g e , a n d it
m a y s t r e t c h o r s h r in k b e c a u s e of c h a n g e s in t e m p e r a t u r e of h u m id ity .
If
s u c h a d is to r t e d d a ta s e t h a s to b e o v e r l a id o n a n o n d is to r te d o n e, th e d i s to r t io n s m u s t b e e lim in a te d .
O n ly l i n e a r d is to r tio n c a n b e e ffe c tiv e ly
c o r r e c te d b y e c o n o m ic m a n u a l p r o c e s s e s .
A tr a n s p a r e n c y of th e s o u r c e
m a t e r i a l h a s to b e p r o d u c e d a t a s c a l e th a t c a n b e a c c e p te d b y a p r o je c to r ,
a n d th is p r o c e s s i t s e l f m a y in tro d u c e in a c c u r a c ie s , p a r t ic u l a r ly if th e
63
tr a n s p a r e n c y h a s to b e s m a l l.
P r o d u c tio n o f la r g e tr a n s p a r e n c ie s r e d u c e s
th e e r r o r , b u t r e q u i r e s co p y c a m e r a e q u ip m e n t.
T h e im a g e c a n b e m a d e
to f it c o n tr o l p o in ts d ra w n on th e im a g e p la n e , b y a p r o c e s s s i m i l a r to th a t
of r e c tif y in g p h o to g ra p h s .
B e c a u s e of th e n a t u r e of th e p r o c e s s , a n d b e c a u s e
i t i s d iffic u lt e i th e r to c o r r e c t n o n lin e a r d is to r t io n s o r to a s s u m e th a t th e
d is to r tio n of th e s o u r c e d a ta i s in fa c t li n e a r , th e p r o c e s s i s r a r e l y u s e d .
M in o r d is to r tio n s in g r a p h ic s o u r c e d a ta a r e u s u a lly ig n o re d , o r a t b e s t
"a llo w e d f o r " w h en m a p p e d data, a r e h a n d le d m a n u a lly .
N o n lin e a r D is to rtio n E lim in a tio n a n d M ap P r o je c tio n C han g e
T h e s e p r o c e d u r e s do n o t le n d th e m s e lv e s to o p tic a l o r p h o to g ra p h ic p r o c e s s e s ,
s o th e t r a n s f e r of d a t a f r o m s o u r c e m a t e r i a l to a new f o r m a t is a c h ie v e d b y
ey e a n d h a n d .
C a lc u la te d r e f e r e n c e p o in ts a r e u s e d a s a . g u id e, fo llo w e d b y
in te r p o la tio n b e tw e e n d a t a e le m e n ts w h en s u ffic ie n t n u m b e rs h a v e b e e n
t r a n s f e r r e d ; if g r e a t c a r e i s e x e r c is e d th e a c c u r a c y c a n b e h ig h .
ta k e n m a in ly d e p e n d s o n th e n u m b e r of d a ta p o in ts t r a n s f e r r e d .
T h e ti m e
A s in g le
20 -in . x 20 -in . o u tlin e m a p of p o li tic a l b o u n d a rie s an d m a in p h y s ic a l f e a t u r e s
o f w e s te r n E u r o p e , f o r e x a m p le , w o u ld ta k e m o r e th a n one m a n -d a y .
The
e f f o r t r e q u i r e d f o r th e m a n u a l m e th o d m e a n s th a t it is g e n e ra lly u n d e rta k e n
b y c a r to g r a p h ic h o u s e s r a t h e r th a n b y r e s e a r c h g e o g ra p h e r s .
G ROU PING
G ro u p in g e n c o m p a s s e s s e v e r a l, te c h n iq u e s u s e d to change th e f o r m o f th e
d a ta in a m a p p r i o r to data, e x tr a c tio n . 1 I t in c lu d e s th e r e l a ti v e ly s im p le
c o n c e p ts o f m e r g in g data, o r s e t s o f d a ta an d d is s o lv in g re d u n d a n t d a ta
e le m e n ts ( fo r e x a m p le , re m o v in g a li n e th a t s e p a r a t e s tw o a r e a s o f th e s a m e
k in d , w h ic h m a y h a v e r e s u l t e d f r o m e i th e r m e r g in g o r m a tc h in g e d g e s).
It
a ls o in c lu d e s " m o d a l c h a n g e " a n d th e " g e n e ra te " p r o c e s s , w h e re d a ta e l e m e n ts a r e g ro u p e d o r r e p r e s e n t e d on th e m a p b y a n ew ly g e n e ra te d d a ta
e le m e n t o r e l e m e n t s ( e .g ., c e n tr o id a llo c a tio n , c o n to u rin g , g e n e ra liz a tio n ) .
A ll th e s e te c h n iq u e s in v o lv e s e le c tiv e p r o c e s s e s a s w e ll a s p u r e ly m e c h a n ic a l
r e p r o d u c tio n ; th e l a t t e r m a y b e h a r d e r to a c c o m p lis h th a n th e f o r m e r .
1. B o th " im a g e m a n ip u la tio n " a n d "g ro u p in g " in v o lv e th e c r e a tio n o f a new
r e c o r d , i . e . , a new m a p , and,, i n th a t s e n s e , c o u ld b e te r m e d " m a p c o m p ila tio n " . T h e l a t t e r te r m , h o w e v e r, i s fre q u e n tly u s e d to d e s c r ib e th e
a s s e m b ly o f s p a t i a l d a t a to p r o d u c e a n o r ig in a l m a p . A s th is d is c u s s io n
c o n c e rn s i t s e l f w ith te c h n iq u e s th a t a r e e m p lo y e d o n ly a f t e r th e o r ig in a l
m a p h a s b e e n p ro d u c e d , th e t e r m " m a p c o m p ila tio n " h a s n ot b e e n em p lo y ed
in t h e i r d e s c r i p tio n t o av o id c o n fu sio n .
64
M e rg e an d D is so lv e
T o m e r g e i s t o c o m b in e c o n tig u o u s a r e a s th a t q u a lify f o r in c lu s io n in a new
c a te g o r y o r s e t of c a te g o r ie s , a n d to d is s o lv e i s to re m o v e a co m m o n
b o u n d a r y b e tw e e n s p e c if ie d a r e a s a n d to g ro u p th e m in a sin g le a r e a .
E i th e r th e e n t ir e f il e c a n b e t r a c e d (o r p h o to g ra p h ic a lly re p ro d u c e d ) w ith th e
a p p r o p r i a te e le m e n ts o m itte d o r m a s k e d , o r th e o r ig in a l f ile c a n b e a m en d ed .
E x c e p t w hen m in o r c h a n g e s a r e m a d e to a n e x is tin g f il e , e ith e r p r o c e s s is
r a t h e r la b o r io u s .
T h e m a t e r i a l of th e s o u r c e d o cu m en t, th e n u m b e r of
c h a n g e s , a n d th e n e a tn e s s r e q u i r e d in th e f in a l d o cu m en t h av e a s u b s ta n tia l
e f fe c t on th e tim e in v o lv e d .
S ta b le - b a s e p h o to s e n s itiv e m a te r i a ls h av e b e e n
d e v e lo p e d on w h ic h d a ta f r o m tr a n s l u c e n t s in g le -to n e s o u r c e m a te r i a l ca n
b e c o p ie d a n d f r o m w h ic h d a ta c a n b e re m o v e d b y e l e c tr i c a l ly p o w e re d
erasu re.
H o w e v e r, i f th e s o u r c e m a t e r i a l i s c o lo u r - p rin te d p a p e r an d
c o lo u r w a s h e s m u s t b e c h a n g e d in th e m e r g e d a r e a s , th e d o cu m en t m u s t b e
c o m p le te ly r e p r i n t e d u s in g c o r r e c t e d c o lo u r s e p a r a tio n p la te s .
E d g e M atch
T h e s a m e d if fic u ltie s h a v e to b e f a c e d w h en th e e d g e s of a d ja c e n t m a p s a r e
m a tc h e d .
T o e d g e -m a tc h one s h e e t, e ig h t o th e r s h e e ts m u s t b e e x a m in e d
v is u a l ly a n d c o r r e c t i o n s m a y b e r e q u i r e d on f o u r o r m o r e of th e m .
The
ti m e ta k e n v a r i e s w ith th e n u m b e r o f m is m a tc h e s to b e c o r r e c te d and
n u m b e r of r e f e r e n c e s th a t m u s t b e m a d e to d a ta s o u r c e s , b u t th e le v e l o f
e f f o r t r e q u i r e d c a n b e u n d e rs to o d .
T h e b r i e f d is c u s s io n of m a n u a l te c h n iq u e s f o r h a n d lin g s p a tia l d a ta so f a r
h a s in d ic a te d th e r e l a t i v e l y la b o r io u s n a t u r e of c e r t a in of t h e i r o p e r a tio n s .
T h is p a r t i c u l a r l y a p p lie s to th e p r o c e d u r e s in v o lv in g th e t r a n s f e r of d a ta
f r o m one m e d iu m to a n o th e r , e s p e c i a ll y i f i t i s n o t a li n e a r p r o c e s s .
On
t h e ot h e r h a n d , th e s e le c ti v e p r o c e s s u n d e rta k e n b y th e h u m a n m in d a s an
in t e g r a l p a r t of m a n u a l g r a p h ic d a ta p r o c e s s in g i s o fte n e x tr e m e ly e ffic ie n t.
T h is i s i l l u s t r a t e d in s o m e of th e te c h n iq u e s d e s c r ib e d b elo w .
C e n tr o id A llo c a tio n
C e n t r o id a llo c a t i o n i s th e d e te r m in a tio n of th e c e n tr e of a d a ta c l u s t e r
a c c o r d in g to a g iv e n a lg o r ith m .
T h e a lg o r ith m c a n p r e s c r i b e w h e th e r i t b e
th e c e n tr e of m a s s , a c e n tr e c o n st r a in e d w ith in th e b o u n d a ry o f th e a r e a .
65
o r th e c e n tr e of a r e a s , l i n e s , c l u s t e r s of li n e s , o r c l u s t e r s o f p o in ts .
The
e y e , h a n d , a n d b r a i n c a n p e r f o r m th i s ta s k e a s ily , a s it in v o lv e s p a t te r n
re c o g n itio n b o th to c a lc u la te th e p o s itio n of th e c e n tr o id in th e d a ta c l u s t e r
an d to s e p a r a t e th e d a ta c l u s t e r f r o m o th e r e le m e n ts in th e s p a ti a l f ile .
C a lc u la tio n of th e c e n tr o id , a r a t h e r co m p le x p r o c e s s in t e r m s o f th e
d e c is io n s in v o lv e d , i s done a lm o s t in s ta n ta n e o u s ly .
C o n s id e r a b ly m o r e
t i m e , h o w e v e r, i s n e e d e d a c tu a lly to p lo t th e c e n tro id on th e g r a p h ic m e d iu m .
O n a ty p i c a l 2 0 -in . x 3 0 -in . m a p of p r e s e n t la n d u s e a t a s c a le o f 1 :5 0 ,0 0 0 ,
w ith 2 ,0 0 0 p a tc h e s of h o m o g e n e o u s la n d u s e , e a c h of w h ic h r e q u i r e s a
c e n tr o id , th e p r o c e s s ta k e s a p p r o x im a te ly 2 h o u r s f o r p o in t a llo c a tio n (3
h o u r s i f th e p o in ts a r e s e q u e n tia lly n u m b e re d o n th e m a p a s th e y a r e in s e r t e d ) ,
a n d a f u r t h e r 1 h o u r t o c h e c k th a t n o n e h a v e b e e n m i s s e d .
T he sa m e e ffi-
c i e n c ie s a p p ly in th e t a s k s of m a n u a l c o n to u rin g a n d m a n u a l g e n e ra liz a tio n .
C o n to u rin g
C o n to u rin g , th e c r e a tio n of is o lin e s th ro u g h a s e r i e s of p o in ts w ith v a r i a b le
v a lu e s , r e l i e s upon v is u a l e x a m in a tio n of th e o r ig i n a l d a t a s e t a n d a
d e c is io n -m a k in g p r o c e s s to d ir e c t th e d ra w in g of is o lin e s th r o u g h th e p o in ts
b y hand.
C o n flic ts of in t e r p r e ta tio n m a y o r m a y n o t b e r e s o lv e d b y r e f e r e n c e
to a d d itio n a l d a ta .
T h e m a n u a l a p p ro a c h h a s th e a d v a n ta g e th a t i t m a k e s
im m e d ia te u s e of th e r e l e v a n t know ledge of a d ra u g h ts m a n .
G e n e ra liz a tio n
In g e n e ra liz a tio n , e le m e n ts of s p a ti a l d a ta , p o s s ib ly w ith m u ltiv a r ia b le
c l a s s i f ic a t io n s , a r e c o m b in e d in to a s in g le l a r g e r e le m e n t w ith a s in g le
c l a s s i f ic a t io n , u s u a lly b a s e d on th e p r o p o rtio n of th e o r ig i n a l s e p a r a t e
c l a s s i f ic a t io n s c o n ta in e d in th e new s p a ti a l d a ta e le m e n t.
T he p ro cess is
e s s e n ti a ll y a s o p h is tic a te d s e q u e n c e of m e rg in g , d is s o lv in g , a n d g e n e ra tin g
c a lc u la te d a c c o r d in g to a s e t of r u l e s .
T h e te c h n iq u e i s u s e d w h e n th e
c o m p le x ity of d a ta p r o h ib its s e n s ib le d is p la y a t th e d e s ir e d s c a l e , a n d i s o f
p a r t i c u l a r s ig n ific a n c e w h en th e r e s u lt in g g ra p h ic d is p la y i s to b e th e o n ly
p la c e w h e r e th e s e d a ta a r e s to r e d .
s c ie n c e .
G e n e ra liz a tio n i s p a r t a r t a n d p a r t
T h e d e g re e to w h ich d a ta c a n b e cro w d e d on a p a r t i c u l a r m a p
s h e e t i s f re q u e n tly d e te rm in e d b y m e n ta l e v a lu a tio n of t h e e a s e w ith w h ic h
th e m a p s h e e t c a n b e r e a d , o r th e o v e r a l l a e s t h e ti c s of c o lo u r o r lin e
p a t te r n s .
H e re a g a in , th e m e n ta l p r o c e s s e s of g r a p h ic s e le c tio n a r e
66
e x t r e m e l y e ff ic ie n t.
O nce th e d e c is io n s h a v e b e e n m a d e , th e new b o u n d a r ie s
m a y b e tr a c e d s e le c ti v e ly f r o m l a r g e r - s c a l e s h e e t s , th e im a g e s r e d u c e d
p h o to g ra p h ic a lly , an d th e d a ta e le m e n ts r e la b e lle d ; li n e s m a y b e s m o o th e d ;
o r , f o r e x t r e m e g e n e r a liz a tio n , th e o r ig in a l d a ta m a y b e sy m b o liz e d .
The
te c h n iq u e s u s e d in th e s e d if f e re n t a p p ro a c h e s m a y v a r y , an d c a n b e m ix e d
o n th e s a m e s h e e t.
A ll th e p h y s ic a l o p e r a tio n s a r e la b o rio u s an d in v o lv e
th e c r e a tio n of a new s p a t i a l d a ta f ile .
T h e ti m e an d e f fo r t ta k e n n e c e s s a r i ly
d ep e n d on th e a r e a to b e c o v e re d a n d , in p a r t i c u l a r , on th e r u le s o f th e
g e n e ra liz a tio n .
DATA EX TR A C TIO N
D a ta e x t r a c ti o n i s th e d u a l p r o c e s s of s e le c ti n g an d r e t r i e v i n g d a ta f r o m th e
g r a p h ic s to r a g e f il e f o r s u b s e q u e n t d e c is io n -m a k in g p u rp o s e s .
“ D a ta s e le c tio n " d e p e n d s o n th e r e q u i r e m e n t s of th e p a r t ic u l a r d e c is io n s to b e
m a d e , a n d i s b a s e d on a p r i o r i k now ledge of th e c o n te n ts o f th e f il e , o r on
th e h e u r i s t i c p r o c e s s of b r o w s in g th ro u g h th e f il e ( in te r a c tiv e f il e s e a r c h ) ,
o r , m o re u s u a lly , on a c o m b in a tio n of th e tw o a p p ro a c h e s .
T h e m e n ta l
p r o c e s s e s of s u c h id e n tif ic a tio n a n d s e le c tio n a r e e s s e n ti a ll y lo g ic a l c o m p a r is o n s of th e f il e e le m e n ts w ith m e n ta l s e t s of d a ta , o r r u le s p r e s c r i b e d b y
a d e c is io n -m a k in g p r o c e s s .
A s th e a b i lit y to b ro w s e th ro u g h g ra p h ic
s to r a g e f i l e s r e l a t e s to th e p h y s ic a l p r o c e s s o f d a ta e x tr a c tio n , it w ill b e
b r ie f ly e x a m in e d in th i s s e c tio n o f th e c h a p te r.
" D a ta r e t r i e v a l " e n c o m p a s s e s th e d ir e c t r e a d in g of d a ta e le m e n ts w r itt e n
in th e s p a ti a l f il e a n d a l s o th e r e t r i e v a l of d a ta in h e re n t in th e s t r u c t u r e o f
th e f il e c o n te n ts .
T h is l a t t e r a s p e c t of d a ta r e t r i e v a l in c o r p o r a te s m e a s u r e ­
m e n t a n d c o m p a r is o n , w h ic h a r e c o n tro lle d b y th e d a ta s e le c tio n p r o c e s s
a n d w h ic h c a n b e e i t h e r m e n ta l (e s tim a tio n ) o r p h y s ic a l.
E i th e r ty p e ,
m e n ta l o r p h y s ic a l, c a n b e u s e d to id e n tify d a ta e le m e n ts , id e n tify a n d
r e t r i e v e d a ta p a t t e r n s , c o m p a re s e p a r a t e d a ta e le m e n ts o r p a t te r n s , a n d
s u p e r im p o s e d a ta e le m e n ts o r p a t te r n s .
D a ta r e t r i e v a l i s c o m p le te d b y
m o v in g th e s e le c te d d a ta e le m e n ts o r r e s u l t s of th e m e a s u r e m e n t o r c o m p a r i s o n to a n o th e r f o r m o f s to r a g e , e i th e r m e n ta l o r p h y s ic a l.
T h e m e n ta l
o p e r a tio n s in v o lv e d in m e a s u r e m e n t a n d c o m p a ris o n a r e o u ts id e th e s c o p e
o f th i s t h e s i s , b u t th e p h y s ic a l p r o c e s s e s o f m e a s u r e m e n t an d c o m p a r is o n
67
f o r m a s u b s t a n ti a l p a r t of th e te c h n iq u e s f o r m a n u a lly h a n d lin g g ra p h ic d a ta .
T h e m a n u a l o p e r a tio n s in v o lv e d in th e s e p r o c e s s e s in c lu d e th e a b ility to
r e a d , s e a r c h , m o v e ( tr a n s f e r d a ta f r o m o n e r e c o r d to a n o th e r), m e a s u r e ,
a n d c o m p a re .
S om e e x a m p le s th a t i l l u s t r a t e th e tim e an d e f f o r t in v o lv e d
in th e s e ta s k s a r e g iv e n b elo w .
D a ta S e le c tio n
R e a d in g . R e a d in g i s b y no m e a n s s im p le a n d s tr a ig h tf o r w a r d .
C h a r a c te r
r e c o g n itio n i s a c o m p le x p r o c e s s th a t th e h u m a n m in d c a n do w e ll, g iv e n
a d e q u a te tr a in in g , b u t th a t c o m p u te rs ca n n o t (h en ce th e n e e d to ch a n g e
g r a p h ic d a ta in to s p e c i a l m a c h in e - r e a d a b le c o d e s a s a n e s s e n ti a l f i r s t s te p
in m a c h in e d a ta h a n d lin g ).
F u r t h e r m o r e , r e a d in g g ra p h ic f il e s im p lie s
th e a b ility to in t e r p r e t th e s y m b o ls a n d p a r t i c u l a r l y th e co n v e n tio n s u s e d in
th e c a rto g r a p h ic d is p la y s .
It r e q u i r e s m e n ta l a d a p ta tio n to th e c o n s tr a in ts
o f th e s e g r a p h ic la n g u a g e s w h en e s tim a tio n an d m e a s u r e m e n t o f th e g r a p h ic
f i l e a r e in v o lv ed .
It i s n o t u n u s u a l f o r th e r e a d in g of a 20 -in . x 3 0 - in .
to p o g ra p h ic m a p s h e e t, u n d e r ta k e n to d e te r m in e p r in tin g e r r o r s , to ta k e
10 h o u r s , a n d th e ti m e i s c o rr e s p o n d in g ly lo n g e r f o r s h e e ts w ith h ig h
d e n s it ie s o f d a ta .
S uch r e a d in g f o r e d itin g p u r p o s e s d o e s , o f c o u r s e ,
in c lu d e th e tim e u s e d f o r m e n ta l c o m p a r is o n s w ith a g iv e n s e t of e d i to r ia l
r u l e s , b u t i t in d ic a te s th e g e n e ra lly slow n a t u r e of th is b a s ic a s p e c t o f
m an u al re trie v a l.
T h e r e a d in g p r o c e s s i t s e l f i s n o t f r e e f r o m e r r o r s .
It
i s co m m o n p r a c t i c e to u s e m o r e th a n one e d i to r f o r m a p c h e ck in g , n o t o n ly
b e c a u s e one p e r s o n c a n in tro d u c e e r r o r s in to th e in f o rm a tio n a s it i s b e in g
r e a d , b u t b e c a u s e o n e p e r s o n c a n o m it to r e a d p a r t of th e f il e a tte n tiv e ly ,
e v e n th o u g h i t h a s b e e n v is u a lly s c a n n e d b y th a t p e rs o n .
T h e tim e in v o lv e d in r e a d in g a p a r t i c u l a r g ra p h ic d a ta s e t is a fu n c tio n o f
r e a d in g c a p a b ility a n d f i l e s iz e .
A lthough m a p s h e e t s a r e th o u g h t o f a s a
c o m p a c t a n d s y m b o lic f o r m of d a ta s to r a g e , th e n u m b e r o f s h e e ts r e q u i r e d
to c o n ta in e v e n a li m it e d a m o u n t of th e s p a ti a l d a ta a lr e a d y g a th e r e d f r o m
a p a r t i c u l a r a r e a of th e e a r t h m a y b e la r g e .
tw o e x a m p le s .
T h is ca n b e il l u s t r a t e d b y
T h e fiv e d a ta s e t s (p r e s e n t la n d u s e , a g r i c u lt u r a l c a p a b ility ,
f o r e s t r y c a p a b ility , r e c r e a t i o n s u ita b ility , a n d w ild life h a b ita t s u ita b ility )
c o lle c te d b y th e C a n a d a L a n d In v e n to ry f r o m th e a g r i c u lt u r a l an d p ro d u c tiv e
68
f o r e s t a r e a s of C a n a d a (a p p ro x im a te ly 1 m illio n s q u a r e m ile s ) w i l l c o m p r is e
1 5 ,0 0 0 to 2 0 ,0 0 0 s h e e ts w hen c o m p le te (1 4 ,0 0 0 h av e a lr e a d y b e e n p ro d u c e d ).
O f th e m o r e th a n 500 e l e c tr i c it y u tility c o m p a n ie s in th e U n ite d S ta te s , a
ty p i c a l c o m p a n y h a s 10,0 0 0 to 1 5 ,000 m ap s h e e t s to r e c o r d th e p o s itio n of
i t s p o w e r lin e n e tw o rk .
E ven th e p h y s ic a l s to r a g e r e q u i r e m e n t s o f s u c h
d a ta s e t s a r e n o t in c o n s id e r a b le , an d u s e r s fr e q u e n tly h av e a s u b s e t of
g r a p h i c a ll y s t o r e d m a te r i a l f o r r e g u l a r u s e a n d c e n tr a l (re m o te ) l i b r a r y
f a c i l i t i e s f o r m a in s to r a g e .
T h is m e a s u r a b ly le n g th e n s th e a c c e s s ti m e to
th e to t a l s t o r e a n d h a s s o m e in flu e n c e on th e d a ta r e a d i ly a v a ila b le (h en ce
m o s t u sed ) f o r d e c is io n m a k in g .
F in a lly , th e a c tu a l h a n d lin g o f th e f il e s
c a u s e s e v e n tu a l p h y s ic a l d e t e r io r a t io n of th e im a g e s a n d r e g u l a r m a in te n a n c e
is re q u ire d .
S e a r c h a n d id e n tif ic a tio n .
T h e tim e an d e f f o r t in v o lv ed in a l l ty p e s of
" s e a r c h " o p e r a t io n s , b o th m a n u a l a n d c o m p u te r- a id e d , a r e o b v io u s ly i n flu e n c e d b y th e w ay in w h ich th e d a ta e le m e n ts a r e o r g a n iz e d a n d in d ex e d .
T h e s to r a g e o f g ra p h ic d a ta im p o s e s s e v e r a l s ig n if ic a n t c o n s tr a in ts o n th e
w a y s p a t i a l d a ta a r e f ile d an d on th e v o lu m e of d a ta on a n y o n e r e c o r d .
A tte m p ts to f i l e th e m a n y d iff e re n t ty p e s of in d iv id u a l s p a tia l, data, e le m e n ts
o n s e p a r a t e s h e e t s an d lin k th e m b y lo g ic a l in d e x e s r a p i d l y c r e a t e p r o h ib iti v e ly l a r g e n u m b e rs of s h e e ts .
T o m in im iz e th e n u m b e r o f s h e e t s , s e t s
of r e l a t e d , b u t d if f e re n t, d a ta e le m e n ts a r e fre q u e n tly file d on o n e s h e e t;
f o r e x a m p le , a to p o g ra p h ic m ap sh o w s r i v e r s , b u ild in g s , f o r e s t s , c o n to u rs
of h e ig h t, a n d s o f o r th .
A lte r n a tiv e ly , v a r io u s d a ta e le m e n ts m a y b e c o m -
b in e d a n d c l a s s i f ie d a c c o rd in g to a s e t of r u l e s , a n d o n ly th e r e s u lt in g
c a te g o r ie s a r e show n.
T h e s e p r o c e d u r e s a r e u s e fu l if th e u s e r w is h e s to
c o n s id e r th e r e s u lt in g d a ta s e t s in t h e ir e n t ir e t y , b u t th e y c a n m a k e i t
v e r y d iffic u lt t o s e a r c h f o r s u b s e ts of th e o r ig in a lly g a th e r e d d a t a , a n d w h e r e
r e c l a s s i f i c a t i o n h a s o c c u r r e d m a y e v e n p ro h ib it t h e i r e x tr a c tio n .
T h e f il e s t r u c t u r e u s e d , h o w e v e r, m a y g r e a t ly f a c i li ta te th e s e a r c h p r o c e s s .
In s o m e in s ta n c e s , s u c h a s a to p o g ra p h ic m a p , th e f ile s t r u c t u r e o f th e d a ta
e le m e n t c o n f o r m s a p p ro x im a te ly to o u r p e r c e p tio n of th e v a r i o u s e n v i r o n m e n ta l e le m e n ts , a n d t h e i r r e la tio n s h ip s to e a c h o th e r an d to o u r b e h a v io u r
p a tte rn s .
T h is p r o v id e s u s w ith a s e r i e s of m e n ta l in d e x e s w hich e s ta b lis h
69
a h i e r a r c h y o f v a lu e s f o r d a ta e le m e n ts a n d k e y s to th e ir, s p a ti a l d is tr ib u tio n .1
U se of s u c h e s ta b lis h e d m e n ta l in d e x e s ca n m e a s u r a b ly r e d u c e th e am o u n t
of r e a d in g r e q u i r e d in th e s e a r c h p r o c e s s .
C o n v e n tio n a l p h y s ic a l in d e x in g of g r a p h ic d a ta s to r a g e i s u s u a lly li m it e d to
b r o a d g ro u p s of s u b je c t m a tte r , c r o s s - in d e x e d b y s p a ti a l a t tr ib u t e s .
L ittle
c a n b e a c c o m p lis h e d b y r e f e r e n c e to s u c h s im p le in d e x e s a lo n e , b u t th e y
p ro v id e r a p i d id e n tif ic a tio n of d a ta s e t s f o r s p e c if ic a r e a s ; s u b s e q u e n t
a c c e s s to th e m a p s h e e t s is d ir e c t (ran d o m ) a n d th e ti m e u s e d c a n b e s h o r t.
T h e s to r a g e m e d iu m i s th e s a m e a s th e d is p la y m e d iu m , s o d a ta r e t r i e v a l
c a n b e g in in s ta n tly .
sh e e ts.
B ro w s in g i s g r e a t ly a id e d b y th e ra n d o m a c c e s s to m a p
I t i s e a s y to d is p la y s e v e r a l m a p s h e e ts in r a p i d s u c c e s s io n a n d to
view th e m s id e b y s id e .
F o r s m a l l n u m b e rs of s h e e t s th is is a n e x tr e m e ly
e ffic ie n t o p e r a tio n , b u t if m a n y m a p s a r e d is p la y e d a t o nce it m a y b e c o m e
d iffic u lt f o r th e o b s e r v e r to r e c o g n iz e an d r e t a i n th e im a g e s th e y c o n ta in .
T h is m a y b e a fu n c tio n of low h u m a n "c h a n n e l c a p a c ity " .2 T h e p r o c e s s i s ,
h o w e v e r, e n t ir e l y u n d e r th e c o n tr o l of th e o b s e r v e r a n d b e c o m e s c u m b e r s o m e o n ly i f l a r g e f il e s h a v e to b e s c a n n e d .
W hen th e s im p le in d e x e s allo w
id e n tif ic a tio n of li m it e d s e a r c h a r e a s an d th e a v a ila b le d a ta s e t s a r e c o n v e n ie n tly g ro u p e d , th e m a n u a l p r o c e s s is r a p id , e ff ic ie n t, a n d in e x p e n s iv e .
T h e e n d p ro d u c t of th e s e a r c h a n d id e n tific a tio n p r o c e s s i s s e le c tio n of th e
d a ta e le m e n ts to b e e x t r a c te d f r o m th e f il e .
In m e n ta l t e r m s , th i s in v o lv e s
m a tc h in g th e p a t te r n of th e g ra p h ic e le m e n ts to a g iv e n s e t o f r u l e s o r to
im a g e s b a s e d u p o n a s e t of g ra p h ic r u l e s .
W h e re th e d a ta e le m e n t, f o r
e x a m p le a n a m e , i s w r itt e n in th e f il e , id e n tific a tio n i s a s tr a i g h tf o r w a r d
m a tc h in g p r o c e s s .
W h e re th e d a ta e le m e n t, f o r e x a m p le th e d is ta n c e
b e tw e e n o b je c ts , i s in h e r e n t in th e f il e s t r u c t u r e , th e p r o c e s s e s o f
r e t r i e v a l b y m e a s u r e m e n t o r c o m p a ris o n ( e ith e r m e n ta l o r p h y s ic a l, o r bo th )
m u s t b e c a r r i e d o u t to r e v e a l d a ta th a t m a tc h a s e le c tio n r e q u ir e m e n t.
T h e s e l a t t e r o p e r a tio n s w ill b e e x a m in e d f u r t h e r b elo w .
D a ta R e t r ie v a l
T ra n sfe r .
T h e t r a n s f e r of d a ta e le m e n ts f r o m a g ra p h ic f ile to a s e c o n d
s to r a g e f o r u s e in d e c is io n m a k in g m a y b e a c c o m p lis h e d e i th e r m e n ta lly
1. M ilg r a m 1972, E m e r s o n 1969, S te a 1969, T ro w b rid g e 1913. 2. H u m an
" c h a n n e l c a p a c ity " i s th e m a x im u m r a t e a t w h ich b i t s of in f o r m a tio n c a n
b e t r a n s m i t t e d to th e b r a i n v ia a l l h u m a n s e n s o r y c h a n n e ls .
70
o r p h y s ic a lly .
A s th e f o r m a t of th e m e n ta l s to r a g e i s la r g e ly unknow n, no s e n s ib le c o m m e n t
c a n b e m a d e ab o u t th e m e n ta l p r o c e s s of t r a n s f e r to th a t f o r m o f s to r a g e
e x c e p t th a t it i s r a p i d if th e d a ta a r e s im p le , in v o lv e s o n ly la b o u r c o s ts ,
a n d h a s p ro v e d i t s a b ility .
No m e a s u r e s of im a g e r e te n tio n c a p a c ity a r e
a v a ila b le , b u t it i s th o u g h t th a t a t l e a s t 2 5 0 ,0 0 0 im a g e s a r e f il e d i n s to r a g e
a s p a r t o f th e n o r m a l h u m a n v is u a l re c o g n itio n p r o c e s s .
T h e p ro c e s s in c o r-
p o r a t e s ra n d o m a c c e s s to s u c h im a g e s , a c o m p le x to p o lo g ic a l in d e x ,
b r o w s in g c a p a b ility , a s o p h is tic a te d im a g e - m a tc h in g c a p a b ility , a n d a n
in d iv id u a l im a g e m a tr ix of 1 ,000 b y 1, 000 p o in ts .
T h e r a t e of h u m a n d a ta
t r a n s f e r i s c o n s id e r e d to b e in th e o r d e r of 3 b a u d ,
1w h ic h w o u ld in d ic a te
a r a t h e r low " c h a n n e l c a p a c ity " c o u p le d w ith a h ig h p r o c e s s in g c a p a b ility .
No e s ti m a t e s a r e a v a ila b le f o r th e m o d a l d iv is io n of s u c h d a ta b e tw e e n th e
v a r io u s s e n s o r y c h a n n e ls .
T h e s e f ig u r e s ca n n o t b e s u b s ta n tia te d w ith o u t
e x te n s iv e f u r t h e r in v e s tig a tio n , if a t a l l in th e f o r e s e e a b le f u tu r e , b u t th e y
p r o b a b ly a r e m in im u m s ( p a r t ic u la r ly in th e c a s e of c h a n n e l c a p a c ity ).
They
in d ic a te th e fo r m id a b le c a p a c ity of th e h u m a n s y s t e m of im a g e s to r a g e a n d
m a n ip u la tio n , w h ic h m u s t b e k e p t in m in d w hen a l te r n a t iv e m a c h in e - a id e d
s y s t e m s a r e c o n s id e re d .
T h e p h y s ic a l m o v e m e n t of s e le c te d g r a p h ic d a ta to a s e c o n d s to r a g e i s a n
im a g e t r a n s f e r p r o c e s s a c c o m p lis h e d b y a v a r i e ty of r e a d in g a n d w r itin g
o p e r a tio n s .
T h e o p e r a t o r m a y r e a d th e d a ta e le m e n t a n d w r i t e it o n a
se p a ra te re c o rd .
If th e im a g e i s o th e r th a n s y m b o lic , th e e r r o r le v e l o f
s u c h v is u a l t r a n s f e r m a y b e h ig h ; and, a s a n a lte r n a t iv e , t r a n s f e r m a y b e
m a d e b y c o n ta c t t r a c i n g on to a s e c o n d r e c o r d , o r b y p r o je c tin g th e im a g e
o n to th e s e c o n d r e c o r d a n d tr a c in g th e lig h t im a g e .
If th e im a g e s a r e
e x t r e m e l y c o m p le x a n d tr a c in g w o u ld r e s u l t in a n u n a c c e p ta b le n u m b e r o f
e r r o r s o r e x p e n s e of ti m e , th e n a p h o to g ra p h ic t r a n s f e r p r o c e s s m a y b e
used.
T h e a d v a n ta g e of m a n u a l t r a c i n g i s th a t u n w an te d d a ta c a n b e m e n ta lly
m a s k e d a n d o n ly s e le c te d d a ta n e e d b e t r a n s f e r r e d .
P h o to g r a p h ic d a ta
t r a n s f e r m a y m a k e u s e o f p h y s ic a l m a s k in g , in w h ic h u n w an te d p a r t s o f
e i t h e r th e o r ig in a l im a g e o r i t s p h o to g ra p h ic c o p y a r e c o v e re d .
1 . E d w a rd s 1964, Q u a s tle r 1956.
H o w e v e r,
71
t h i s t a s k i t s e l f m a y b e m o r e la b o r io u s th a n tr a c in g .
A f ilte r can be u sed
in th e p h o to g ra p h ic p r o c e s s to m a s k s p e c ific c o lo u r s o n c o lo u re d o r ig in a ls .
H o w e v e r, p h y s ic a l t r a n s f e r of d a ta f r o m a g r a p h ic s to r a g e f ile to a s e c o n d
s t o r e i s u s u a lly a c c o m p lis h e d b y tra c in g .
E x p e r im e n t a l e v id e n c e th a t r e v e a ls th e d e g re e of e r r o r an d th e e ffo rt
r e q u i r e d in th e p r o c e s s h a s b e e n o b ta in e d in t e s t s of d a ta t r a n s f e r b y
t r a c i n g a n d s c r ib i n g te c h n iq u e s p e r f o r m e d b y th e C a rto g r a p h ic S e c tio n of
th e C a n a d a D e p a rtm e n t o f A g r ic u ltu re in th e G o v e rn m e n t of C an a d a.
D iffe re n t a m o u n ts o f d a ta w e r e c o n ta in e d in th e g ra p h ic s to r a g e f il e f o r
v a r i o u s p a r t s of th e c o u n try .
A c c o rd in g ly , s a m p l e s c o m p r is in g o n e f ile
c o n ta in in g d a ta of a v e ra g e d e n s ity a n d a n o th e r c o n ta in in g d a ta o f low
d e n s it y w e r e c h o s e n f o r th e t e s t s .
T h e f i r s t c o n s is te d of a s o il m a p a n d a
p r e s e n t la n d u s e m a p o f p a r t of G re n v ille C o u n ty in O n ta rio , b o th m a p s a t
a s c a l e o f 1:126, 720.
T w o tr a c in g s f r o m th e p r e s e n t la n d u s e m a p of
G r e n v il l e C o u n ty w e r e m a d e , a n d th e t r a c i n g ti m e s f o r n e a t lin e b o u n d a r ie s
a n d p r e s e n t la n d u s e a r e a b o u n d a r ie s f o r th e e n t ir e m a p s h e e t o f 339 sq . in .
w e r e a s fo llo w s :
a.
E x p e r ie n c e d d ra u g h ts m a n
E d itin g of t r a c i n g p r o c e s s
4 h 35 m in
1h
b.
In e x p e r ie n c e d d ra u g h ts m a n
E d itin g of t r a c i n g p r o c e s s
4 h 40 m in
1 h 30 m in
A v e ra g e ti m e p e r sq . in . of m a p s h e e t
a.
b.
1
m in
1. 1 m in
S c rib in g w a s c a r r i e d o u t a t th e s a m e tim e a s tr a c in g ; th e s c r ib i n g tim e f o r
n e a t lin e a n d p r e s e n t la n d u s e b o u n d a rie s w a s a s fo llo w s:
a.
E x p e r ie n c e d d ra u g h ts m a n
E d itin g
A v e ra g e tim e p e r sq . in . o f m a p s h e e t
3 h 31 m in
35 m in
0. 7 m in
T h e s a m e s c r ib i n g p r o c e d u r e w a s a l s o u s e d to p ro d u c e a co p y o f th e p r e s e n t
la n d u s e m a p o f th e R id in g M ountain a r e a , w ith i t s lo w -d e n s ity d a ta .
The
s h e e t m e a s u r e d 458 s q . in . an d r e q u i r e d 5 h o u r s 12 m in f o r s c r ib i n g a n d
4 7 m in f o r e d itin g .
A v e ra g e tim e p e r s q . in . o f th e m a p s h e e t s c r ib e d b y
a n e x p e rie n c e d d r a u g h ts m a n w a s 0. 8 m in .
I t w a s c o n c lu d e d th a t to t r a n s f e r d a ta f r o m th e s to r a g e f il e b y m a n u a l
tr a c i n g p r o c e s s e s , s c r ib i n g w a s f a s t e r an d m o r e a c c u r a te th a n th e tr a d iti o n a l
72
m e th o d o f in k o r p e n c il tr a c in g .
T h is q u ic k e r m e th o d o f m a n u a l d a ta t r a n s f e r
w a s ta k e n a s a s ta n d a r d f o r e s tim a tio n of th e tim e r e q u i r e d f o r th e tr a c in g
e f f o r t c o n te m p la te d in th e C a n a d a L a n d In v e n to ry .
In th e e x p e r im e n ts ,
s c r ib i n g r e s u lt e d in ti m e s of b etw e en 0. 7 a n d 1. 6 m in p e r sq . in . f o r th e
ty p e a n d d e n s ity of d a ta c o n ta in e d in th e s a m p le f il e of g r a p h ic s to r a g e ,
o r a n e s ti m a t e d la b o u r tim e of b e tw e e n 7 a n d 16 h o u r s to c o m p le te a s h e e t
of 600 s q . in .
A s e t of 500 m a p s w ould in v o lv e b e tw e e n 3 ,5 0 0 a n d 8 ,0 0 0
m a n - h o u r s (19. 9 a n d 45. 5 m a n -m o n th s ).
M o re th a n 1 4 ,0 0 0 m a n u s c r ip t
m a p s h e e t s h a v e b e e n g e n e ra te d b y th e C a n a d a L a n d In v e n to ry .
A lth o u g h
th e i n s tr u m e n ts a n d e q u ip m e n t n e c e s s a r y f o r th i s ty p e of w o rk a r e lim ite d
to n o r m a l d ra u g h tin g f a c i l i t i e s (q u ie t r o o m , t r a c i n g t a b le s , s c r ib e p o in ts ,
a n d s c r ib e c o a t m a te r i a ls a t a c o s t of a p p ro x im a te ly $ 5 . 00 p e r s h e e t) , it
c a n b e s e e n e v e n f r o m th i s in a d e q u a te s a m p le th a t th e r e q u i r e m e n t s of
la b o u r a n d , m o r e im p o r ta n tly , of th e tim e to t r a n s f e r th e d a ta , a r e la r g e .
A p r e l i m i n a r y in v e s tig a tio n of h u m a n t r a c i n g e r r o r w a s c o n d u c te d jo in tly
w ith th e tim in g s tu d ie s .
T h e s a m p le w a s a la n d r e s o u r c e s m a p o f a v e ra g e
d a ta d e n s ity ; th o u g h s u b je c tiv e ly c h o s e n , it w a s r e p r e s e n t a ti v e o f m a n y in
th e C a n a d a L a n d In v e n to ry .
A m a s t e r c o p y o f th e m a p w a s r e p r o d u c e d
p h o to g ra p h ic a lly on s ta b le m a te r i a l.
D ra u g h ts m e n a n d o p e r a t o r s w ith
v a r i o u s d e g r e e s of e x p e rie n c e w e re s e le c te d .
E a c h t r a c e d th e m a s t e r co p y
b y p e n on a tr a n s l u c e n t s ta b le m a te r i a l, f i r s t a t n o r m a l s p e e d , n e x t a t h ig h
s p e e d , a n d f in a lly a t slow s p e e d w ith m a x im u m a c c u r a c y .
A f te r a l l t r a c i n g
h a d b e e n c o m p le te d , a s m a l l a r e a of th e m a s t e r c o p y w a s s e le c te d a n d
e n l a r g e d o n a h ig h - p r e c is io n e n l a r g e r .
T h e s a m e a r e a o n e a c h o f th e tr a c e d
s a m p l e s w a s s i m i l a r l y e n la r g e d , an d d e v ia tio n s f r o m th e o r ig i n a l m o r e th a n
o n e lin e w id e w e r e m e a s u re d .
A s th e d a ta e x t r a c te d w e r e th e b o u n d a r ie s o f
p r e s e n t la n d u s e a r e a s , a n d a s th e f a c t o r c r i t i c a l to s u b s e q u e n t d e c is io n
m a k in g w a s th e m e a s u r e m e n t of s iz e of th e a r e a t r a c e d , th e t r a c i n g e r r o r
w a s e x p r e s s e d in t e r m s of i t s e ffe c t on th e s iz e of th e a r e a s s u b s e q u e n tly
m e a su re d .
B a s e d on th e d a ta r e c o r d e d , i t w a s fo u n d th a t th e e r r o r w a s
c l o s e ly r e l a t e d to b o u n d a ry le n g th of th e s p e c if ic a r e a a n d c o u ld b e e x p r e s s e d
a s 0 . 6 x 10-3 s q . in . of e r r o r p e r li n e a r in c h of b o u n d a ry m e a s u r e d .
T hus,
on a m a p a t 1 :5 0 ,0 0 0 s c a l e , th e a v e ra g e e r r o r in c u r r e d w o u ld b e +
/- 3 a c r e s
in 1, 300 a c r e s .
A lthough th e tim e r e q u i r e d i s s u b s t a n ti a l, th e tr a c in g
73
m e th o d o f g r a p h ic d a ta t r a n s f e r i s th e r e f o r e s u ffic ie n tly p r e c i s e to b e a d e q u a te f o r a w id e v a r i e t y o f d e c is io n - m a k in g p u rp o s e s .
M e a s u r e m e n t a n d c o m p a ris o n . T y p ic a l o p e r a tio n s in v o lv ed in e x tr a c tin g
d a ta in h e r e n t in a g r a p h ic f il e s t r u c t u r e a r e c o u n tin g of d a ta e le m e n ts ,
d e te r m in a tio n of d is ta n c e s an d d ir e c ti o n s , a n d c a lc u la tio n o f th e s iz e of
are a s.
C o m p a ris o n s o f d a ta e le m e n ts , o r of th e r e s u l t s o f t h e i r m e a s u r e -
m e n t, allow id e n tif ic a tio n a n d e x tr a c tio n of s u c h r e la tio n s h ip s a s n e a r e s t
n e ig h b o u rs a m o n g d a ta e le m e n ts , s h o r te s t r o u te s am o n g a l t e r n a t iv e s , a r e a s
w ith s p e c if ic c h a r a c t e r i s t i c s (s u c h a s s iz e ) , an d li n e s of s ig h t.
M e a su re -
m e n t a n d c o m p a r is o n a c c o r d in g to m o re co m p le x s e t s of r u le s p e r m it c o n te x tu a l s e a r c h (id e n tific a tio n of th e o c c u r r e n c e o f s p e c ific d a ta e le m e n ts in
s p e c if ic ju x ta p o s itio n ) , a n d i t s s o p h is tic a te d c a s e , p a t te r n re c o g n itio n .
F u r t h e r e x te n s io n of th i s o p e r a tio n a llo w s th e id e n tific a tio n a n d e x tr a c tio n
of g r o u p s of p a t te r n s o c c u r r i n g a s s p a ti a ll y d is c r e te s e t s , a n d th e m e a s u r e m e n t of s p a ti a l c o r r e l a t i o n s b e tw e e n e le m e n ts o r s e t s of e le m e n ts th a t
in t e r a c t in th e s a m e s p a c e .
A ll m a n u a l d a ta e x tr a c tio n p r o c e s s e s a r e
u n d e r ta k e n u n d e r th e m e n ta l c o n tr o l (m o n ito r) of lo g ic a l r e q u i r e m e n t s
p r e s c r i b e d b y th e d e c is io n - m a k in g p r o c e s s .
T h is fu n c tio n i s ta k e n f o r
g r a n t e d w h e n h u m a n s k ill s a r e u s e d b u t r e p r e s e n t s an e x tr e m e ly h ig h d e g r e e
of s o p h is tic a tio n in c o m p u te r - a id e d te c h n iq u e s .
T h e d if f e re n c e s b e tw e e n th e r e s u l t s o f e s tim a tio n an d p h y s ic a l m e a s u r e m e n t
in c a r r y i n g o u t s i m i l a r fu n c tio n s l i e in t h e i r p r e c is io n a n d th e e f f o r t
r e q u i r e d to a c h ie v e th e m .
T h e n e e d f o r p r e c i s io n sh o u ld , o f c o u r s e , be
d e te r m in e d b y th e in te n d e d u s e of d a ta r e s u lt in g f r o m th e o p e ra tio n .
P r e c i s i o n c a n u s e f u lly b e th o u g h t of a s " re p e a ta b ility " .
I t i s a n o b je c tiv e ly
d e te r m in e d le v e l o f a c tiv ity a t w h ic h it i s d e c id e d to w o rk , a p p r o p r ia te to th e
a i m s of th e e x e r c i s e b e in g c a r r i e d o ut.
A r e l a t e d b u t d if f e re n t p r o p e r ty ,
th a t of " r e s o lu t io n " , i s d ep e n d en t on th e s iz e of th e u n its u tiliz e d f o r m e a s u r e m e n t.
T h e p r e c i s i o n an d r e s o lu t io n of d a ta e x tr a c tio n c l e a r l y a ffe c t th e
s u b s e q u e n t u s e of th e d a ta a n d s i m i l a r l y in flu e n c e th e s p e e d an d le v e l of
e f f o r t n e e d e d to o b ta in th e m .
In t r i v i a l o p e r a tio n s , s u c h a s th e co u n tin g of
a s m a l l n u m b e r of p o in ts , th e d if f e re n c e s a r e s m a l l w h e th e r s u c h an o p e r a tio n i s c a r r i e d o u t m e n ta lly o r w ith th e a id of a s im p le m e c h a n ic a l c o u n te r.
A s th e c o m p le x ity of m e a s u r e m e n t an d c o m p a ris o n in c r e a s e s , h o w e v e r, th e
74
d iffe re n c e b e tw e e n e s tim a tio n a n d p h y s ic a l m e a s u re m e n t b e c o m e s sig n ific a n t
a n d in f lu e n c e s th e u s e s to w h ic h th e re s u lts c a n b e p u t. T h e
d e te r m in a tio n o f d is ta n c e a lo n g a lin e m a y b e u s e d a s a n e x a m p le . F o r
s im p le s h a p e s a n d le n g th s b e tw e e n 0 . 5 in . a n d a p p r o x im a te ly 3 0 in . a n
e s tim a te o f le n g th u s u a lly re s u lts in e rro rs o f ± 5 % . T h is le v e l o f a c c u ra c y
i s a d e q u a te f o r c e r ta i n ty p e s o f d e c is io n m a k in g . F o r in tr i c a te lin e s h a p e s ,
p a r t ic u l a r ly li n e s c o n ta in e d w it h in à n e t w o r k , t h e e r r o r le v e l i n c r e a s e s
s h a r p ly a n d e s t im a tio n b e c o m e s l e s s u s e f u l fo r t h e s a m e d e c is i o n - m a k in g
p r o c e s s . P h y s ic a l lin e m e a s u r e m e n t b y v a r io u s m e th o d s , s u c h a s c o m p a r is o n
o f lin e le n g th w ith a s c a le o f k n o w n le n g th ( e ith e r rig id o r f le x ib le ) , m a p
m e a s u r e m e n t b y m o v in g w h e e l ( c u r v im e te r ) , o r c u r s o r tr a v e l m e a s u r e m e n t ,
c a n r e d u c e t h e e r r o r to w it h in ± 4 % o f t h e tr u e m e a s u r e m e n t. D u p lic a tio n
o f m e a s u re m e n ts c a n re d u c e th e e rro r fu rth e r b u t th e tim e re q u ire d
is in c re a se d s u b sta n tia lly , fre q u e n tly b y fa c to rs o f 1 0 o r m o re . A n
e x p e rim e n t w a s c o n d u c te d in w h ic h 1 5 p o in ts w e r e s e le c te d a t r a n d o m o n
a s e c tio n o f a m a p s h e e t th a t in c lu d e d a ro a d n e tw o rk p a tte rn . T h e
s h o r te s t r o a d d is ta n c e s b e tw e e n e a c h p o in t a n d e v e r y o t h e r p o in t w e r e f ir s t
e s ti m a t e d a n d s u b s e q u e n t l y p h y s i c a l l y m e a s u r e d w i t h a m e c h a n i c a l
lin e m e a s u rin g d e v ic e . F in d in g s a re g iv e n in T a b le 3 . 1 .
T im e
S in g le m e a s u r e m e n t
220 m in
A v. % e r r o r
S ta n d a rd d e v ia tio n
of % e r r o r
R an g e of
% e rro r
A s s u m e d to b e z e ro in th is c a s e
C a re fu l e s ti m a t e
50 m in
9. 3%
10. 3
0 - 68. 2%
Q u ic k e s ti m a t e
22 m in
14. 8%
12 .0
0 - 64. 8%
T able 3. 1. S u m m ary of results of distance estim ation and m easu rem en t. T h e
average difference in error betw een the quick estim ate and single m easurem ent was
a p p ro x im a te ly 1 5 % , a n d th e d iffe re n c e in tim e w a s in th e o rd e r o f x 1 0 . M o re
significantly, the individual distances estim ated show ed errors of up to approxim ately
65% . R esults obtained by m easurem ent and estim ation thus differ w idely in their type
o f a p p lic a tio n to d e c is io n m a k in g , a n d r e q u ir e s ig n ific a n tly d if f e r e n t a m o u n ts
o f e ffo rt to a c q u ire . It m u s t a lso b e re m e m b e re d th a t th is is a sim p le a n d
straightforwardexample of data extraction from a graphic storage file.
75
A f u r t h e r e x a m p le of d a t a e x t r a c ti o n i s th e o v e r la y p r o c e s s , o r m e a s u r e m e n t
o f th e in t e r s e c ti o n of s e t s of h o m o g e n e o u s p a tc h e s of a r e a l d a ta th a t o c c u r in
th e s a m e s e c tio n of th e s p a ti a l f ile .
T w o ty p e s of p h y s ic a l m e a s u r e m e n t a r e in co m m o n u s e f o r m a n u a lly
m e a s u r in g a r e a s o n m a p s , one u s in g a p o la r p la n im e te r , th e o th e r a dot a r e a
g r id .
T e s t s w e r e done w ith b o th ty p e s o f m e a s u r e m e n t.
P a r t of th e
p r e v io u s ly m e n tio n e d G re n v ille C o u n ty s o il m a p (1 :5 0 ,0 0 0 s c a le ) w a s o v e r la id w ith a t r a n s p a r e n t m a p a t th e s a m e s c a l e , a n d an a r e a o f 16 s q . in . w as
s e le c te d .
T h e a r e a c o n ta in e d 386 c o m b in a tio n s o f s o il a n d p r e s e n t la n d u s e
in fo rm a tio n , th e s iz e of th e in d iv id u a l p a tc h e s v a r i e d f r o m 1 to 2, 000 a c r e s ,
a n d th e to t a l s iz e o f th e a r e a r e p r e s e n t e d 10, 240 a c r e s on th e g ro u n d .
A
s ta n d a r d e q u a l - a r e a dot g r i d w a s u s e d b e c a u s e th e in h e r e n t e r r o r in tr e a ti n g
m in im u m - s iz e d a r e a s i s s m a l l e r th a n th a t of a ra n d o m do t p a t te r n g r id ,
w h ic h m a y m i s s m a n y s u c h a r e a s a n d e x h ib it c l u s t e r e d p o in t c h a r a c t e r i s t i c s .
T h e p r o c e d u r e i l l u s t r a t e s th e a c tio n s a n d th e u s e of ti m e in v o lv e d in th is
ty p e of m e a s u r e m e n t:
a)
A g r id w a s s e le c te d : 1 dot = 1. 6 a c r e s .
b)
T h e g r id w a s o v e r l a id a n d f ix e d in p o s itio n .
c)
T h e p u n ch c o u n te r w a s u s e d to r e c o r d d o ts , a p e n c il w a s u s e d to m a r k
off m e a s u r e d a r e a s .
W h e re a d o t w a s b is e c te d b y a lin e , a v a lu e o f
o n e -h a lf d o t w a s a s s ig n e d to th e a r e a o n e a c h s id e o f th e lin e .
d)
T h e a r e a of e a c h c o m b in a tio n of p r e s e n t la n d u s e a n d s o ils w a s
m e a s u r e d a n d r e c o r d e d s e p a r a t e l y in ta b u la r f o r m , a s w a s th e
r e q u i r e d ti m e to c o m p le te th e w o r k o n e a c h a r e a .
e)
T a b u la tio n of th e d a ta w a s m a d e o n th e b a s i s of s o il ty p e s a n d p r e s e n t
la n d u s e .
S u m m a tio n of a l l c o m b in a tio n s of a r e a w a s m a d e a n d th e
t o t a l c o m p a re d w ith th e know n a r e a .
T h e t e s t w a s r e p e a te d u s in g a s ta n d a r d p o la r p la n im e te r w ith a tr a c in g p o in t,
in s te a d o f th e dot g r id .
T h e a r m w a s a d ju s te d to s c a le an d r e a d in g s w e r e
ta k e n to t h r e e d e c im a l p la c e s .
a)
P ro c e d u re :
T h e o p e r a t o r t r a c e d a ro u n d th e a r e a to b e m e a s u r e d a n d r e c o r d e d th e
r e a d in g in s q u a r e in c h e s f r o m th e V e r n ie r s c a le .
b)
T h e o p e r a tio n w a s r e p e a te d t h r e e t i m e s , o r u n til th r e e re a d in g s
d iffe re d b y l e s s th a n 0 .0 0 3 s q . in .
76
c)
T h e a v e ra g e r e a d in g w a s r e c o r d e d .
d)
O p e ra tio n t i m e s w e r e r e c o r d e d a s f o r th e d o t g r id m e th o d .
e)
A r e a ta b u la tio n s w e r e m a d e a s f o r th e dot g r id m e th o d .
C o m p a r is o n of r e s u l t s of t e s t s on 16 s q . in . of m ap s h e e t a r e g iv e n in
T a b le 3. 2.
O p e ra tio n
D ot a r e a g rid
T im e to m e a s u r e a r e a s
9 h 6 m in
T im e f o r e d itin g a n d ta b u la tio n
3h
T o t a l ti m e
12 h 6 m in
P o l a r p la n im e te r
14 h 36 m in
3h
17 h 36 m in
A v e r a g e ti m e p e r s q . in . of m a p s h e e t
45 m in
65 m in
D iffe re n c e b e tw e e n s u m o f p a tc h s iz e s
a n d to t a l s iz e o f a r e a b e in g m e a s u r e d
± 2%
1 3. 7%
±
T a b le 3. 2.
S u m m a ry of r e s u l t s of a r e a m e a s u r e m e n t te s t .
T h e r e s u l t s show th a t th e dot g r id p ro v id e s a c o n s id e r a b ly f a s t e r an d s o m e w h a t m o r e a c c u r a te m e th o d of m e a s u r in g m a p a r e a s .
S im i la r a r e a m e a s u r e m e n t s w e r e o b ta in e d f r o m th e R id in g M o u n tain m ap
s h e e t.
T h e s c a l e of m a p a n d o v e r la y w a s 1:126, 720, a n d th a t o f th e dot
a r e a g r id w a s 1 d o t = 13 a c r e s .
T w o h u n d re d s q u a r e in c h e s o f m a p s h e e t
w e r e m e a s u r e d , e d ite d , a n d ta b u la te d (4 47,000 a c re s ) a t th e r a t e of ab o u t
5 m in p e r s q . in .
T h is r a t e r e f l e c t s tw o th in g s: th e r e l a ti v e c o a r s e n e s s of
th e g r id a n d th e low in fo r m a tio n d e n s ity of th e d a ta in th e g r a p h ic s to r a g e
f il e .
P e r c e n t a g e e r r o r w a s s lig h tly m o re th a n 3% f o r th e to t a l a r e a .
M e a s u re m e n t o f low - d e n s it y m a p d a ta u s in g a c o a r s e dot g r id th u s r e q u i r e d
a p p r o x im a te ly 5 m in p e r s q . in . a n d m e a s u r e m e n t of n o r m a l- d e n s it y m ap
d a ta u s in g a f in e d o t g r id u tiliz e d 45 m in p e r sq . in .
A lthough th e d ot a r e a
g r id m a y p ro v id e th e f a s t e r a n d m o r e a c c u r a te m e th o d of m e a s u r in g m a p
a r e a s , th e b e s t ti m e f o r a s q u a r e in c h of m a n u a l m e a s u re m e n t a p p a re n tly
f a l l s b e tw e e n 5 a n d 45 m in f o r th e c o m p a r is o n of tw o ty p e s o f d a ta .
T h is
d o e s n o t in c lu d e th e p r e p a r a tio n o f th e m a p s , b u t d o es in c lu d e th e m e a s u r in g ,
e d itin g , a n d w r itt e n ta b u la tio n of th e r e s u l t s .
T h e a b o v e t e s t s w e r e c a r r i e d out b e c a u s e m e a s u r e m e n t a n d c o m p a r is o n s
b e tw e e n m a p s c o n ta in in g d iffe re n t ty p e s of d a ta w e r e d e s ir e d a s an a id to
u n d e rs ta n d in g th e q u a lity a n d v a r io u s c h a r a c t e r i s t i c s of th e a g r i c u lt u r a l
77
la n d in C a n a d a .
'
G iv en a n a v e ra g e m a p of 600 s q . in . (20 in . x 30 in . ) an d
a s s u m in g th a t a n a v e r a g e of 400 s q . in . w o u ld b e of in t e r e s t f o r a p a r t ic u l a r
e x a m in a tio n , th e ti m e in v o lv e d f o r th e c o m p a ris o n of one s e t o f 500 m a p s
w ith a n o th e r 500 w o u ld b e b e tw e e n
= 852 m a n - m o n th s .
= 94. 7 m a n -m o n th s an d
T h e s e ti m e s m u s t b e m u ltip lie d b y th e
n u m b e r of c o m p a r is o n s th a t n e e d to b e m a d e , th a t i s , th e n u m b e r of t i m e s
it i s w is h e d to c o m p a re a n y tw o ty p e s o f d a ta th ro u g h o u t th e in v e n to r y a r e a .
T h e s m a l l - s c a l e , h ig h e r - s p e e d a p p ro a c h r e s u l t s in th e b r o a d e s t s p a ti a l
c o m p a r is o n o f t h e d a t a in v o lv e d .
If f in e r g r id s a r e u s e d f o r m e a s u r e m e n t
a n d c o m p a r is o n of m o r e d e ta ile d d a ta , th e m in im u m ti m e s in v o lv e d f a ll
c l o s e r to th e m id d le of th e g iv e n ra n g e .
T h e s e f ig u r e s ca n n o t b e e x te n d e d in to e s ti m a t e s of th e to t a l ti m e a n d e f f o r t
n e e d e d m a n u a lly to e x t r a c t d a ta f r o m a g iv e n s e t of m a p s u n le s s o n e c a n
d e c id e , in a d v a n c e , how m a n y m a p s h a v e to b e e x a m in e d a n d how m a n y
c o m p a r is o n s h a v e t o b e m a d e .
Som e m a p s m ig h t b e e x p e c te d to b e th e
s u b je c t of n u m e r o u s c o m p a r is o n s , b u t r e l a ti v e ly few c o m p a r is o n s w o u ld
n e e d to b e m a d e o n a c o u n try w id e b a s i s .
N e v e r th e le s s , th e a m o u n t o f tim e
a n d e f f o r t n e e d e d to c a r r y o u t m a n u a l m e a s u r e m e n t a n d c o m p a r is o n i s e v i d e n t a n d a n y l a r g e v o lu m e o f m a p s w o u ld n e c e s s a r i l y m e a n a lo t o f w o rk .
E q u ip m e n t a n d in s tr u m e n ta tio n n e c e s s a r y f o r m e a s u r in g a n d e d itin g ,
h o w e v e r, a r e li m it e d to n o r m a l d ra u g h tin g f a c i l i t i e s , th e p r o v is io n o f
p r e c i s io n d o t g r i d s a t a p p r o x im a te ly $ 15 p e r s e t , o r p la n im e te r s a t a c o s t
of $65 e a c h .
I f m e a s u r e m e n t a n d c o m p a r is o n a r e r e p la c e d b y e s tim a tio n , l e s s e f f o r t
w o u ld b e n e e d e d a n d m o r e e r r o r c o u ld b e e x p e c te d .
I f o th e r e s ti m a t e s
o f c o r r e l a ti o n b e tw e e n th e d a ta s e t s w e r e a p p lic a b le to th e t a s k fa c in g th e
u s e r , th e n s a m p lin g p r o c e d u r e s b a s e d on f e w e r m a n u a l m e a s u r e m e n ts
a n d c o m p a r is o n s c o u ld y ie ld u s e f u l r e s u l t s .
In e a c h c a s e , a g e n e r a l le v e l
of p r e c i s io n i s r e l a t e d t o a n a p p r o x im a te le v e l o f e f f o r t.
In th e e x a m p le
of m e a s u r e m e n t a n d c o m p a r is o n p ro v id e d , th e r e s u lt in g d a ta w e r e n e e d e d
to e x a m in e th e a c tu a l r e l a ti o n s h i p b e tw e e n p r e s e n t la n d u s e a n d s o il
c h a r a c t e r i s t i c s i n c o u n tie s w ith v a r y in g s o c io -e c o n o m ic c h a r a c t e r i s t i c s ,
a s a b a s i s f o r id e n tify in g m a r g in a l f a r m in g t r a c t s in C an a d a.
78
SUM M ARY
T h is c h a p te r h a s fo c u s s e d on th e u ti lit y of th e m a p a s a s o u r c e o f d a ta f r o m
w h ic h in fo rm a tio n h a s to b e e x tr a c te d .
G e n e r a l c a te g o r ie s o f m a n u a l t e c h -
n iq u e s f o r h a n d lin g m a p p e d d a ta h a v e b e e n e x a m in e d a n d t h e ir e ffic ie n c y
h a s b e e n il l u s t r a t e d w ith s e le c te d e x a m p le s .
S e v e r a l c o n c lu s io n s c a n b e
d ra w n f r o m th e e v id e n c e p r e s e n te d .
F r o m a s im p l is tic , e m p ir ic a l p o in t of v ie w , i t c a n b e n o te d th a t f o r a s in g le
a r b i t r a r y a r e a of ab o u t 10 s q . in . of m a p s h e e t, th e v a r io u s s im p le t e c h n iq u e s of im a g e m a n ip u la tio n , g ro u p in g , r e a d in g , s e a r c h , s e le c tio n ,
t r a n s f e r , a n d m e a s u r e m e n t b y e s tim a tio n e a c h ta k e a p p ro x im a te ly 1 to 30
m in to a c c o m p lis h .
T h e r e i s w id e v a r i a ti o n w ith in th a t r a n g e d e p e n d in g on
th e ap p ro a c h u s e d , th e d e n s ity of d a ta in th e f il e , an d s o f o r th .
F o r th e
o p e r a tio n s of m e a s u r e m e n t a n d c o m p a ris o n , h o w e v e r, th e tim e a n d e f f o r t
r e q u i r e d r i s e s h a r p ly to b e tw e e n a p p r o x im a te ly 80 a n d 650 m in f o r th e
s in g le 10 s q . in .
T h is i s i l l u s t r a t e d on th e fo llo w in g g ra p h (F ig . 3. 1).
In h e r e n t d a ta
e x tr a c tio n
W r itte n d a ta
m a n ip u la tio n an d
e x tr a c tio n
T im e
Non-Linear
Estima-
M anual te c h n iq u e s
F ig . 3. 1.
R e la tio n s h ip b e tw e e n ty p e of m a n u a l te c h n iq u e a n d tim e u s e d .
T w o c o m m e n ts m a y b e m a d e ab o u t th e r e l a ti o n s h i p show n .
F ir s t, m ost
te c h n iq u e s th a t f a l l below th e b r e a k in s lo p e (a p p ro x im a te ly 3 m in p e r s q . in . )
s e e m to b e th o s e th a t y ie ld a r e a s o n a b l e r e t u r n f o r e f f o r t.
T h e y p r o b a b ly
79
a r e c u r r e n t ly c o n s id e r e d to b e e c o n o m ic a lly p r a c t i c a l a s m a n u a l w o rk in g
to o l s .
S eco n d ly , th e s e te c h n iq u e s o p e r a te on th e d a ta w r itt e n o n th e m ap .
O p e ra tio n s to e x t r a c t d a ta in h e r e n t in th e f il e s t r u c t u r e of th e m a p f a l l ab o v e
th e b r e a k in s lo p e a n d ra p id ly b e c o m e u n e c o n o m ic a l.
I t c a n r e a s o n a b ly b e
c o n c lu d e d th a t if m a n u a l te c h n iq u e s a r e u s e d , g r a p h ic s o u r c e d a ta h a v e low
u ti lit y w h en d a ta in h e r e n t i n the. f i l e s t r u c t u r e h a v e to b e e x tr a c te d .
T h e a b o v e o b s e r v a tio n s w e r e d e riv e d f r o m th e tim e a n d e f f o r t in v o lv e d in
h a n d lin g th e o r e ti c a ll y a s in g le s m a l l p ie c e of g ra p h ic s o u r c e d a ta .
F ro m
th e e v id e n c e in th e te x t i t i s r e a s o n a b le to a s s u m e th a t tim e a n d e ffo rt
in c r e a s e in p r o p o r tio n to t h e v o lu m e of g ra p h ic d a ta to b e h a n d le d .
T h is
m a y n o t b e a li n e a r f u n c tio n , a s in c r e a s in g d a ta v o lu m e b r in g s p h y s ic a l
h a n d lin g p r o b le m s in a d d itio n t o t h e tim e r e q u i r e d f o r d a ta m a n ip u la tio n
a n d e x tr a c tio n .
H o w e v e r, f o r th e p u r p o s e s of th i s a r g u m e n t th e r e la tio n s h ip s
c a n b e c o n s id e r e d to b e l i n e a r ( y = x ), a s sh o w n in th e d ia g r a m (F ig . 3. 2).
T im e
V olum e of g r a p h i c s o u r c e d a ta
F ig . 3. 2.
R e la tio n s h ip b e tw e e n d a ta v o lu m e an d tim e r e q u i r e d f o r d a ta
m a n ip u la tio n a n d e x tr a c tio n .
W hen th e r e l a ti o n s h i p b e tw e e n m a n u a l te c h n iq u e s an d ti m e is c o n s id e r e d ,
th e c u r v e r a p i d ly s te e p e n s (y = a x ).
T im e
In h e r e n t d a ta e x tr a c tio n
W ritte n d a ta m a n ip u la tio n
a n d e x tra c tio n
M an u al te c h n iq u e s
F ig . 3. 3.
R e la tio n s h ip s b etw e en m a n u a l te c h n iq u e s , v o lu m e o f d a ta ,
an d tim e u s e d .
80
I t c a n e a s i ly b e s e e n (F ig . 3. 3) th a t in c r e a s in g d a ta v o lu m e ra p id ly
d e c r e a s e s th e ty p e of m a n u a l te c h n iq u e th a t ca n b e c o n s id e r e d e c o n o m ic a l.
I t a l s o i l l u s t r a t e s th e p o in t th a t in c r e a s in g d a ta v o lu m e ra p id ly m a k e s
u n e c o n o m ic a l th e m a n ip u la tio n an d e x tr a c tio n of d a ta a c tu a lly w r itt e n in th e
f ile .
T h e e ffe c t o f in c r e a s in g d a ta v o lu m e i s p a r t ic u l a r ly s ig n ific a n t, a s
i n c r e a s e s in f il e fle x ib ility in a g ra p h ic m e d iu m u s u a lly im p ly c r e a tio n of
m u ltip le g r a p h ic r e c o r d s a n d h e n c e in c r e a s e th e b i t s of d a ta to b e h a n d le d .
G ra p h ic s o u r c e m a t e r i a l th u s im p o s e s an in h e r e n t in fle x ib ility o n f ile
s t r u c t u r e s , a n d h a s low u tility a s a s o u r c e of l a r g e v o lu m e s o f s p a tia l d a ta .
F r o m a th e o r e ti c a l p o in t of v ie w , it c o u ld b e s a id th a t m a n u a l te c h n iq u e s
f o r h a n d lin g m a p p e d d a ta a r e r e l ia n t p a r t l y on m a n u a l m o to r p r o c e s s e s ,
p a r t l y on m e n ta l d a ta p r o c e s s in g , an d p a r t ly on h u m a n c h a n n e l c a p a c ity .
F r o m th e e x a m p le s d is c u s s e d in th is c h a p te r , i t m ig h t b e r e a s o n e d th a t
m a n u a l m o to r p r o c e s s e s a r e r e l a ti v e ly slo w , th a t m e n ta l g ra p h ic d a ta
p r o c e s s in g i s r e l a ti v e ly f a s t, an d th a t h u m a n c h a n n e l c a p a c ity i s a p p a re n tly
lim ite d .
In g e n e r a l, th e n , te c h n iq u e s th a t r e l y m a in ly o n m a n u a l m o to r
p r o c e s s e s , s u c h a s d a ta t r a n s f e r b y tr a c in g o r m a n u a l m e a s u r e m e n t, a r e
s lo w .
T e c h n iq u e s th a t r e l y m a in ly on m e n ta l d a ta p r o c e s s in g a r e f a s t; f o r
e x a m p le , e s tim a tio n of lin e le n g th is a p p ro x im a te ly 10 ti m e s f a s t e r th a n
m a n u a l m e a s u r e m e n t o f th e s a m e li n e s .
T e c h n iq u e s th a t r e l y o n c o m b in a -
tio n s o f m a n u a l m o to r p r o c e s s e s an d m e n ta l d a ta p r o c e s s in g in c r e a s e in
e f fic ie n c y w ith th e p r o p o r tio n of m e n ta l d a ta p r o c e s s in g in v o lv ed , u n til
h u m a n c h a n n e l c a p a c ity i s re a c h e d .
T w o e x a m p le s c a n b e u s e d to i l l u s t r a t e th i s l a s t p o in t.
T h e f i r s t is c e n tr o id
a llo c a tio n , a n o p e r a tio n c o m b in in g m e n ta l d a ta p r o c e s s in g an d m a n u a l m o to r
p ro cesses.
T h is te c h n iq u e i s e c o n o m ic a lly a c c e p ta b le u n til v e r y co m p le x
a r e a s a r e e n c o u n te r e d (su ch a s a m a tr ix in w h ich m a n y is la n d s a r e s tu d d e d ),
a t w h ic h p o in t m e n ta l r e t r i e v a l of th e im a g e i s s o co m p le x th a t c h a n n e l
c a p a c ity i s e x c e e d e d a n d th e e r r o r in v o lv ed in c e n tro id p la c e m e n t b e c o m e s
v e r y h ig h .
T h e s e c o n d e x a m p le i s e s tim a tio n of lin e le n g th , w h ich
o p e r a t e s a t r a t e s of a p p ro x im a te ly 15% e r r o r w h en li n e s a r e s h o r t, b u t
w h ic h r a p i d ly i n c r e a s e s in e r r o r r a t e f o r lo n g co m p le x lin e s .
T h e se
r e l a ti o n s h i p s c a n b e e x p r e s s e d d ia g r a m m a tic a lly a s fo llo w s ( F ig . 3 .4 ).
81
H u m an c h a n n e l c a p a c ity
T im e
T y p e of m a n u a l te c h n iq u e
I n c r e a s e in m a n u a l m o to r co m p o n en t
I n c r e a s e in m e n ta l p r o c e s s in g c o m p o n en t
F ig . 3. 4.
R e la tio n s h ip b e tw e e n c o m p o n e n ts of m a n u a l te c h n iq u e s
a n d tim e u s e d .
I t m u s t b e e m p h a s iz e d th a t no m e a s u r e s of h u m a n c h a n n e l c a p a c ity w e r e
u n d e rta k e n d u r in g th e w o rk on w h ic h th i s c h a p te r i s b a s e d , a n d th e r e f o r e
th e s e r e m a r k s a r e e s s e n ti a ll y s p e c u la tiv e .
F r o m th e e m p ir ic a l e v id e n c e
th a t h a s b e e n p re s e n te d , h o w e v e r, i t m a y b e r e a s o n a b le to c o n c lu d e th a t if
c o m p u te r - a id e d te c h n iq u e s a r e to im p ro v e on m a n u a l te c h n iq u e s f o r
h a n d lin g m a p p e d d a ta , su c h im p ro v e m e n t m ig h t p r o f ita b ly b e so u g h t in
o p e r a tio n s th a t r e d u c e m a n u a l m o to r p r o c e d u r e s a n d th a t allo w th e
p r e s e n t a tio n of d a ta to a u s e r in a f o r m th a t d o e s n o t o v e r lo a d h is c h a n n e l
c a p a c ity .
A n e x a m in a tio n of c u r r e n t c o m p u te r - a id e d te c h n iq u e s f o r
h a n d lin g m a p p e d d a ta i s p r e s e n te d in th e n e x t c h a p te r .
82
C H A P T E R 4 - C U R R EN T C O M P U T E R -A ID E D SYSTEM S F O R H ANDLING
M A P P E D AND O T H E R L O C A T IO N -S P E C IF IC DATA
C o m p u te r-a id e d te c h n iq u e s f o r h a n d lin g m a p p e d an d o th e r lo c a tio n - s p e c if ic
d a ta m a y b e d e s c r ib e d a s c u r r e n t if th e y a r e b e y o n d th e d e v e lo p m e n t s ta g e
an d h a v e b e e n im p le m e n te d in g o v e rn m e n t o r a c a d e m ic s y s te m s f o r
h a n d lin g s p a ti a l d a ta , f o r p u r p o s e s o th e r th a n th e d e v e lo p m e n t o f th e
te c h n iq u e s th e m s e lv e s .
A s p a ti a l d a ta h a n d lin g " s y s te m " in th i s s e n s e i s
ta k e n to b e a s e t of o n e o r m o re c o m p u te r - a id e d te c h n iq u e s f o r r e a d in g ,
s to r in g , m a n ip u la tin g , a n d d is p la y in g s p a ti a l d a ta .
Such s y s te m s h a v e
b e e n d e v ise d m a in ly in th e p a s t d e c a d e , a n d th e f ie ld c o n tin u e s to d e v e lo p
ra p id ly .
T o u n d e rs ta n d th e c o n trib u tio n of th e c u r r e n t s y s t e m s , it i s
n e c e s s a r y to e x a m in e th e m in th e c o n te x t of t h e i r d e v e lo p m e n t to d a te .
B e fo r e 1960, c o m p u te rs w e r e e s s e n ti a ll y h ig h -s p e e d c a lc u la tin g m a c h in e s .
L a r g e a m o u n ts of d a ta co u ld b e m a n ip u la te d in th e c o m p u te r s , b u t t h e i r
li m it e d in t e r n a l s to r a g e c a p a c ity w a s a s ig n ific a n t c o n s tr a in t o n t h e i r u s e .
T h e e a r l y to m id -1 9 6 0 s saw th e d e v e lo p m e n t of c o m p u te r s w ith v e r y l a r g e
m a g n e tic s to r a g e c a p a c itie s , in e x c e s s of o n e m illio n c h a r a c te r s .
T h is
d e v e lo p m e n t a llo w e d r a p i d g ro w th in th e u s e o f c o m p u te r s f o r in f o r m a tio n
h a n d lin g an d , in p a r t i c u l a r , o p en e d th e d o o r to th e n o n -g r a p h ic s to r a g e o f
s p a ti a l d ata.
T h e c o m p u te r s to r a g e of s p a ti a l d a ta h a s tw o a d v a n ta g e s .
T h e f i r s t i s th e
r e l a ti v e ly c o m p a c t n a tu r e of th e s to r a g e c o m p a r e d w ith c o n v e n tio n a l g r a p h ic
s to r a g e .
T h e s e c o n d ad v a n ta g e i s m o r e c r u c i a l, s in c e it ad d s a new
d im e n s io n to th e f i r s t ; th i s i s th e a b ility to u s e e s ta b lis h e d co m p u tin g
m a c h in e s to r e a d , s t o r e , an d m a n ip u la te n o n -g ra p h ic s t o r e s o f s p a ti a l
d a ta .
In a d d itio n , s u c h s t o r e s of d a ta a r e r e l a ti v e ly e a s y to a u g m e n t,
e d it, an d c o r r e c t w ith o u t re n e w in g th e e n t ir e s to r a g e .
A n o b v io u s u s e of n o n - g ra p h ic s to r a g e i s to c o lle c t to g e th e r th e n u m e r ic a l
r e s u l t s of th e m a n u a l p r o c e s s e s of to p o g r a p h ic s u r v e y , in p r e p a r a tio n f o r
v a r io u s f o r m s of g r a p h ic o u tp u t.
A d v a n c e s in th is a r e a s te m m e d f r o m th e
w o rk of p h o to g r a m m e tr is ts w ith c o m p u te r s in th e 1950s, an d s y s t e m s o f
in s tr u m e n ts now e x is t th a t allow m e a s u r e m e n ts f r o m p h o to g ra p h s to b e
t r a n s f e r r e d d ig ita lly to m a g n e tic ta p e (a u to m a tic p h o to g ra m m e try ).
The
83
u s e of n o n - g ra p h ic s to r a g e b y tr a d iti o n a l m a p -m a k in g in s titu tio n s (a u to m a tic
c a r to g r a p h y ) , h o w e v e r, h a s g ro w n o n ly m o re r e c e n tly .
E x is tin g s y s te m s
c a n now ta k e n u m e r ic a l s u r v e y d a ta a s t h e i r d ir e c t in p u t an d p r o c e s s it
d ig ita lly to p ro d u c e a n o n - g r a p h ic s to r e of s p a tia l d a ta ; th is c a n e a s i ly b e
d is p la y e d , u p d a te d , a n d e d ite d .
A ls o , p lo ttin g m a c h in e s c a n now a c c u r a te ly
c o n v e rt a n o n - g ra p h ic s to r e in to a g r a p h ic d is p la y .
T h e s e s y s t e m s of
a u to m a tic c a rto g r a p h y , h o w e v e r, a r e s t i l l in t h e ir in fa n c y o r , a t b e s t, at
a n e x p e rim e n ta l s ta g e .
A t p r e s e n t (1974), no e x te n s iv e n o n - g r a p h ic s to r e
of to p o g ra p h ic in fo rm a tio n h a s b e e n g e n e ra te d d ir e c tl y f r o m n u m e r ic a l
s u r v e y d a ta .
T h e e x is te n c e of l a r g e an d g ro w in g s t o r e s of s p a tia l d a ta in g ra p h ic fo r m ,
an d th e a b ility of p r e s e n t - d a y c o m p u te r s to m a n ip u la te n o n - g r a p h ic s to r a g e ,
h a v e le d to th e d e v e lo p m e n t of te c h n iq u e s to c o n v e rt g ra p h ic to n o n - g r a p h ic
f o r m a t s a n d to m a n ip u la te th e r e s u lt in g s t o r e s of n o n -g r a p h ic s p a ti a l d a ta .
S e v e r a l m e th o d s now e x is t f o r s u c h tr a n s f o r m a tio n .
O nce a n o n -g ra p h ic
f il e of s p a ti a l d a ta h a s b e e n c r e a te d , d a ta m a y b e a d d e d to it w ith o u t
p a s s in g th ro u g h a g ra p h ic s ta g e .
V a rio u s n o n -g ra p h ic d a ta f o r m a ts an d
r e l a t e d f il e s t r u c t u r e s h a v e b e e n d e v e lo p e d , w ith d if fe rin g d e g r e e s of
re s o lu t io n a n d a b ility to h a n d le th e o r ig in a l d a ta .
E a r ly e f f o r ts in s u c h
tr a n s f o r m a tio n e m p lo y e d s im p le d a ta f o r m a ts a n d f il e s t r u c t u r e s , s e v e r a l
o f w h ic h a r e s t i l l in w id e s p r e a d u s e (fo r e x a m p le , g r id s y s te m s ) .
The
g e n e r a l a c c e p ta n c e o f th e s e a p p r o a c h e s sh o u ld p e rh a p s b e q u e s tio n e d ,
b e a r i n g in m in d th e r e l a ti o n s h i p b e tw e e n d a ta a v a ila b ility an d th e d e c is io n m a k in g p r o c e s s .
M o re s o p h is tic a te d n o n -g ra p h ic d a ta f o r m a ts an d f ile
s t r u c t u r e s h av e b e e n d e v e lo p e d a n d a r e b e c o m in g m o re w id ely u s e d .
The
v a r i o u s m a n ip u la tio n f a c i li tie s th a t h a v e b e e n d e v e lo p e d r e l y to a c o n s id e r a b le e x te n t upon th e f il e s t r u c t u r e s to w h ic h th e y a r e ap p lied .
A lth o u g h th e p r o c e s s e s o f h a n d lin g s p a ti a l d a ta h a v e u n d erg o n e c o n s id e r a b le
d e v e lo p m e n t in th e p a s t d e c a d e , c u r r e n t te c h n iq u e s a r e in a tr a n s i tio n
phase.
A t p r e s e n t t h e i r d a ta a r r a n g e m e n t s a r e b a s e d , w ith few e x c e p tio n s ,
o n lo c a l a p p lic a tio n s .
T h e in t e r n a t io n a l a d o p tio n of co m m o n d a ta f o r m a ts
a n d f il e s t r u c t u r e s i s a tr e n d w h ich m u s t b e e x p e c te d , h o w e v e r, an d th is
s ta n d a r d iz a tio n m a y b e h a s te n e d b y th e n e e d to m o n ito r e n v iro n m e n ta l
84
v a lu e s o n a n in t e r n a t io n a l-sc a le .
g a th e r in g in s ti tu ti o n s .
It m a y b e p r e s c r ib e d b y tr a d iti o n a l d a ta
W e s h a ll a ls o s e e th e d e v e lo p m e n t of s y s t e m s th a t
c a n a c c e p t n u m e r ic a l d a ta f r o m s u r v e y in s tr u m e n ts to au g m en t e s ta b lis h e d
n o n - g r a p h ic d a t a b a s e s .
W ith in th e n e x t d e c a d e a l s o , c o m p u te rs th a t u s e
o p tic a l, h o lo g ra p h ic , o r a d v a n c e d f o r m s o f e le c tro m a g n e tic s to r a g e w ill
p ro b a b ly b e c o m e a v a ila b le , a llo w in g no n co d ed (fo r e x a m p le , g ra p h ic ) d a ta
t o b e s t o r e d a n d m a n ip u la te d .
T h is w ill s u b s ta n tia lly r e d u c e th e n e e d to
c o n v e rt g r a p h ic s o u r c e d a ta to c o d e d n o n -g ra p h ic f o r m a ts an d , w ith th e
ad v e n t of e c o n o m ic a l p ic tu r e p r o c e s s in g , w ill m e a s u r a b ly in c r e a s e th e
ra n g e of g r a p h ic d a ta ty p e s th a t c a n b e p r o c e s s e d .
T h e tr e n d of th e s e
d e v e lo p m e n ts i s sh o w n s c h e m a ti c a ll y (F ig . 4. 1).
R eal
w o r ld
O b s e rv a tio n
M e a s u re m e n t
G ra p h ic
s o u r c e d a ta
N o n -g ra p h ic
s o u r c e d a ta
C u rre n t p ra c tic e
L i m it e d c u r r e n t p r a c t ic e
T r e n d o f f u tu r e d e v e lo p m e n t
F ig . 4 . 1.
N o n -c o d ed
c o m p u te r
s to r a g e
G e o -c o d in g
C o d ed n o n g ra p h ic
fo r m a t
C o d ed
c o m p u te r
s to r a g e
D e v e lo p m e n ts in d a ta flow .
B e fo re f u tu r e t r e n d s a r e d is c u s s e d , h o w e v e r, it i s th e p u r p o s e o f th is
c h a p te r to e x a m in e c u r r e n t l y d e v e lo p e d te c h n iq u e s f o r h an d lin g m a p p ed
d a ta a n d t o c o n s id e r th e u ti lit y
of c o m p u te r s to r a g e a s a s o u r c e o f d a ta
f r o m w h ich in fo r m a tio n h a s to b e e x tra c te d .
BASIC CO NSID ERA TIO NS
F o r a l l c o m p u te r s i n g e n e r a l u s e in 1974, m a p p e d an d r e l a te d lo c a tio n s p e c i f ic d a t a a r e r e t a i n e d in a co d e d , n o n - g r a p h ic f o r m o f s to r a g e .
The
1. T h e " u tility " o f a s t o r e o f in fo r m a tio n f o r d e c is io n - m a k in g p u r p o s e s is
d e p e n d e n t u p o n 1) w h e th e r th e ty p e s of d a ta in th e s t o r e a r e r e le v a n t to th e
d e c is io n s b e in g m a d e , 2) w h e th e r th e re s o lu tio n of th e d a ta e le m e n ts (an d b y
im p lic a tio n t h e i r f o r m a t) i s r e l e v a n t to th e d e c is io n s b e in g m a d e , an d 3) how
e a s i ly th e d a ta in th e s t o r e c a n b e m a n ip u la te d (co m b in ed , c o r r e l a te d , c o m p a r e d , e tc .) t o p ro d u c e th e in fo r m a tio n on w h ich th e d e c is io n s c a n b e m a d e .
T h e r e l a ti o n s h i p b e tw e e n s t o r e s of in fo rm a tio n a n d d e c is io n -m a k in g p r o c e s s e s w ill b e e x a m in e d l a t e r in th e th e s i s . In th i s c h a p te r a tte n tio n w ill b e
fo c u s s e d o n d a ta h a n d lin g te c h n iq u e s f r o m a f u n c tio n a l s ta n d p o in t. T h e
" u ti lit y " of co m p ut e r s to r a g e in th i s s e n s e r e f e r s to th e lim ita tio n s a n d c a p a b il i t i e s in h e r e n t i n n o n - g r a p h ic s to r a g e f o r r e c o r d in g an d m a n ip u la tin g
g r a p h ic s o u r c e data.
85
c h a r a c t e r a n d th e u ti lit y of th a t s to r a g e a r e fu n c tio n s of th e ty p e o f n o n g r a p h ic d a ta f o r m a t o r f o r m a ts u s e d a n d th e ch o ic e of f ile s tr u c t u r e
e m p lo y e d (F ig . 4 . 2).
C O M P U T E R STORAGE
C h o ic e o f c o d e d
n o n - g ra p h ic f o r m a t
S o u rc e d a ta
F ig . 4. 2.
C h o ic e of
f ile s tr u c t u r e
U tility
C o m p o n e n ts of c o m p u te r s to r a g e .
I n v e r y g e n e r a l t e r m s , th e c h o ic e of co d e d d a ta f o r m a t d e te r m in e s w h at
s u b s e q u e n tly c a n b e done w ith th e d a ta , an d th e ch o ic e of f il e s tr u c t u r e
d e te r m in e s th e r e l a ti v e e a s e of th e v a r i o u s m a n ip u la tiv e p o s s ib ilitie s .
T h e s e tw o a s p e c t s of c o m p u te r s to r a g e a r e o b v io u s ly c lo s e ly in t e r r e la te d .
Of th e tw o , th e c h o ic e o f c o d e d f o r m a t i s p e r h a p s th e m o s t c r i t i c a l a s it
c a n h a v e im p a c t on th e c o n te n t of th e d a ta .
T r a n s f o r m a tio n s of d a ta to
v a r io u s c o d e d f o r m a ts , o r f r o m one c o d e d f o r m a t to a n o th e r , in c e r t a in
c i r c u m s ta n c e s c a n r e s u l t in in fo rm a tio n l o s s .
b elo w .
T h is i s e x a m in e d m o r e fu lly
T r a n s f o r m a tio n s b e tw e e n f il e s t r u c t u r e s , on th e o th e r h a n d , a r e
fu n c tio n s of ti m e a n d c o s t, th e s e in t u r n b e in g r e l a t e d to th e c a p a b ilitie s o f
th e c o m p u te r b e in g u s e d .
T h e ty p e of f il e s t r u c t u r e u s e d w ill b e (o r sh o u ld
be) g u id e d b y th e in te n d e d u s e of th e d a ta , w h e re a s i t s c o m p le x ity is
d ir e c tl y d e p e n d e n t on th e c o d e d n o n - g r a p h ic f o r m a t a n d th e v o lu m e o f d a ta
to b e h a n d le d .
CO DES F O R N O N -G R A P H IC S P A T IA L DATA
T w o b r o a d c a te g o r ie s of c o d e s f o r n o n - g r a p h ic s to r a g e of s p a ti a l d a ta ca n
b e re c o g n iz e d .
T h e f i r s t of th e s e i s m e tr ic co d in g , b a s e d on a g e o m e tr ic a l
c o o rd in a te s y s te m ; if a h ig h d e g r e e of a c c u r a c y in g e o g r a p h ic a l lo c a tio n s
i s r e q u i r e d , th e n s o m e f o r m of m e tr ic c o d in g m u s t b e em p lo y ed .
The
s e c o n d i s to p o lo g ic a l c o d in g , w h ic h d e fin e s th e lo c a tio n s o f d a ta e le m e n ts
in s p a c e w ith r e s p e c t to o n e a n o th e r , b u t w ith o u t r e f e r e n c e to a c tu a l
d is ta n c e s .
Q u ite r ig o r o u s to p o lo g ic a l g r a m m a r s ca n b e d ev e lo p ed to d efin e
s p a ti a l r e la tio n s h ip s in w a y s th a t g r e a t ly f a c i li ta te d a ta e d itin g , d a ta m a n ip u la tio n , a n d d a ta r e t r i e v a l f o r s p e c ific p u r p o s e s .
E i th e r c a te g o r y o f
86
c o d in g c a n b e a p p lie d to a g iv e n s e t o f s p a tia l d a ta , b u t p o w e rfu l c a p a b ilitie s
f o r d a t a m a n ip u la tio n c a n b e d ev e lo p ed w h en b o th a p p ro a c h e s a r e u s e d in
c o m b in a tio n on th e s a m e d a ta s e t.
N O N -G R A P H IC F IL E O F S P A T IA L DATA
T o p o lo g ic a l
co d e (optional)
M e tr ic code
(o p tio n al)
D a ta in p u t & r e t r i e v a l p ath
S o u rc e d a ta
o r re trie v a l
req u est
F ig . 4. 3.
D a ta in p u t a n d r e t r i e v a l p a th s .
T h e d ia g r a m of d a ta in p u t an d r e t r i e v a l p a th s (F ig . 4 . 3) il l u s t r a t e s th e la s t
p o in t.
b o th .
A g iv e n s e t of s o u r c e d a ta m a y b e co d e d m e tr ic a lly , to p o lo g ic a lly , o r
I f b o th m e th o d s a r e e m p lo y e d , a r e q u e s t f o r r e t r i e v a l of s o u r c e d a ta
m a y e n t e r th e f il e v ia th e to p o lo g ic a l c o d e s, w h ic h c a n b e u s e d a s an in d ex
to th e m e t r i c d a ta , o r v ia th e m e tr ic c o d e s , w h ich c a n b e u s e d a s an in d e x
t o th e to p o lo g ic a lly c o d e d d a ta ; th e ch o ic e d e p e n d s on th e n a tu r e of th e
e n q u ir y .
I n a d d itio n , to p o lo g ic a l c o d e s c a n b e u s e d in c o n ju n c tio n w ith
m e t r i c c o d e s to r e d u c e th e am o u n t of o v e r a l l s to r a g e re q u ir e d .
A ll m e t r i c c o d e s r e l y e i th e r im p lic itly o r e x p lic itly o n a c o o rd in a te s y s te m .
A s m e n tio n e d in C h a p te r 3, a t p r e s e n t th e o n ly w id e ly a c c e p te d m o d e l o f
th e s p a c e o c c u p ie d b y th e e a r t h i s E u c lid e a n .
T h e p r im a r y c a te g o r y of
n o n - g r a p h ic s to r a g e w o u ld s e e m to b e th e n u m e r ic a l r e c o r d of lo c a tio n s in
t e r m s o f t h e i r th r e e - d im e n s i o n a l s p a ti a l c o o rd in a te s .
H o w e v er, r e la tiv e ly
c o m p le x c a lc u la tio n s a r e r e q u i r e d to m a n ip u la te th i s ty p e o f c o o rd in a te
s y s t e m , th e in te r p o la tio n of d a ta e le m e n ts is a l s o c o m p le x , an d t h e r e a r e
c u r r e n t l y few g o v e rn m e n t d e c is io n -m a k in g p r o c e s s e s th a t r e q u i r e d a ta to
b e m a n ip u la te d on a th r e e - d im e n s i o n a l g lo b a l b a s is ; th is i s t h e r e f o r e an
u n c o m m o n f o r m of n o n -g r a p h ic s to r a g e a t th e m o m e n t.
F u tu r e d e v e lo p m en t
of g lo b a l e n v ir o n m e n ta l m o n ito r in g s y s te m s m a y r e q u i r e tr a n s f o r m a tio n of
s o m e ty p e s of d a ta to s u c h f o r m s of n o n -g r a p h ic s to r a g e .
87
P la n e g r a p h ic r e p r e s e n t a ti o n s (m ap s) o f th e c u r v e d s u r f a c e of th e e a r t h a r e
d e v is e d b y m a th e m a tic a l tr a n s f o r m a tio n s .
T h e lo c a tio n o f d a ta e le m e n ts
m a p p e d on th e p la n e c a n th u s b e n u m e r ic a l ly co d e d b y m a p c o o rd in a te s .
S im ila rly , d a ta ca n b e c o d e d in t e r m s of a n a r b i t r a r y s y s t e m o f p la n e
c o o r d in a te s s u p e rim p o s e d on th e m a p .
S uch a r b i t r a r y co d in g i s u s e d , f o r
e x a m p le , in c o n ju n ctio n w ith an a u to m a tic tr a c in g in p u t d ev ice; o r to a id
s u b s e q u e n t c o m p u ta tio n w ith in th e c o m p u te r; o r to h e lp tr a n s f o r m a r b i t r a r y
c o o rd in a te v a lu e s to th e o r ig i n a l p la n e c o o rd in a te s y s t e m o r to a n o th e r
s y s te m .
In a p la n e c o o rd in a te s y s t e m , th e c o o rd in a te s ca n b e u s e d a lo n e , to d efin e
th e lo c a tio n o n th e p la n e of p o in ts (of p la c e s o r e v e n ts ) , a r b i t r a r i l y s h a p e d
a r e a s (s u c h a s g r id s ) , lin e s of a n y c o n fig u ra tio n an d , b y e x te n s io n , a r e a
b o u n d a r ie s of a n y c o n fig u ra tio n .
T h e s p a ti a l ju x ta p o s itio n o f s u c h d a ta
e le m e n ts i s m a d e e x p lic it in t h e i r c o o r d in a te d e fin itio n s .
A t th e o th e r e n d of th e r a n g e of n o n - g r a p h ic d a ta f o r m a ts i s th e e x c lu s iv e
u s e of to p o lo g ic a l c o d e s to r e c o r d s p a ti a l d a ta e le m e n ts .
T h e s im p l e s t f o r m
i s a n o m in a l co d e w h ich id e n tifie s d a ta a s b e lo n g in g to a p a r t ic u l a r g e o g r a p h ic a r e a o r lo c a tio n .
T h is v a lu e d o e s n o t co n v e y r e l a ti v e lo c a tio n d ir e c tl y ,
b u t m u s t b e u s e d in c o n ju n c tio n w ith a n e x t e r n a l m e tr ic in d e x , ty p ic a lly a
m ap.
C o m m o n am o n g s u c h n o m in a l c o d e s a r e n u m b e r s o r n a m e s id e n tify in g
a d m in is tr a tiv e a r e a s , s t r e e t a d d r e s s e s , c e n s u s t r a c t s , tr a f f i c z o n e s , a n d
s o f o r th .
M o st e x is tin g g e o g r a p h ic a lly r e f e r e n c e d d a ta th a t a r e n o t m a p p e d
e m p lo y th i s d e s c r ip tiv e co d in g m e th o d .
S till a t th e e x c lu s iv e ly to p o lo g ic a l e n d of th e r a n g e is th e u s e o f c o d e s th a t
s p e c ify th e r e l a ti v e lo c a tio n of d a ta e le m e n ts (fo r e x a m p le , p o in t c o n n e c ti v i t i e s , g r id c e ll c o n tig u itie s , n e tw o rk s , a n d a r e a a d ja c e n c ie s ) b u t w h e r e
th e a c tu a l lo c a tio n o f th e d a ta e le m e n ts in s p a c e m u s t s t i l l b e d e te r m in e d
f r o m a n e x t e r n a l in d e x .
A u s e f u l e x a m p le of th i s a p p ro a c h i s a b a s i c D IM E1
fil e w h ich p ro v id e s a to p o lo g ic a lly r ig o r o u s c o n n e c tiv ity co d e f o r c ity s t r e e t s
w ith o u t n e c e s s a r i ly m a p p in g th e r e s u lt in g n e tw o rk in s p a c e .
B e tw e e n th e e x t r e m e s of e x c lu s iv e ly m e t r i c o r e x c lu s iv e ly to p o lo g ic a l
1. DIM E i s th e D u al In d ep en d e n t M ap E n c o d in g s y s t e m (U. S. B u r e a u o f
C e n s u s 1972).
88
c o d in g i s th e c o m b in e d u s e of th e tw o ty p e s o f c o d e (F ig . 4 .4 ) .
O nly m e tr ic
c o d e s u sed *
P u re
C o o r d in a te
d e fin itio n
M e tr ic a n d to p o lo g ic a l c o d e s u s e d *
D a ta c o m p a c tio n
fu n c tio n s
→
D a ta c o n n e c tiv ity
fu n c tio n s
D e c r e a s e in u s e of m e tr ic co d e s
O nly to p o lo g ic a l
codes used*
N am es re fe rrin g
to e x te r n a l
m e tr ic in d e x
* " U s e d " in th i s s e n s e m e a n s th a t th e co d e o r c o d e s c o n c e rn e d a r e p a r t of
th e s to r a g e of th e d a ta h a n d lin g s y s t e m an d th e p r o p e r t ie s th e y d e s c r ib e
a r e th u s know n to th e s y s te m .
F ig . 4 . 4.
R e la tio n s h ip b e tw e e n m e t r i c an d to p o lo g ic a l co d e s.
W hen th e m e t r i c a n d to p o lo g ic a l p r o p e r t i e s of th e d a ta s e t a r e know n to th e
s y s t e m to v a r y in g d e g r e e s , v a r io u s ty p e s of c o m p a c tio n of d a ta s to r a g e o r
in d ic a tio n s of d a ta c o n n e c tiv ity , o r b o th , a r e p o s s ib le , though a t th e e x p e n s e of c o m p le x ity of th e f il e s t r u c t u r e (s e e d is c u s s io n o f f ile s tr u c t u r e s
b e lo w ).
T h is c a n b e il l u s t r a t e d w ith e x a m p le s f o r e a c h o f th e fo u r cate-
g o r ie s o f m e t r i c co d e (p o in ts, a r b i t r a r y r e g u l a r a r e a s , lin e s e g m e n ts ,
a n d i r r e g u l a r p o ly g o n s).
P o in ts d e fin e d b y c o o r d in a te s can b e g iv e n n a m e s (ty p ic a lly , n u m b e rs)
← D e c r e a s e in u s e o f to p o lo g ic a l co d e s
w h ic h c a n b e u s e d in s u b s e q u e n t g ro u p in g p r o f e s s e s , th u s a v o id in g th e
r e p e t it io n of t h e i r le n g th y c o o r d in a te s ; th i s i s a s im p le f o r m o f d a ta c o m p a c tio n .
P o in t n a m e s c a n b e r e l a t e d to one a n o th e r b y a p o in t c o n n e c tiv ity
c o d e o r a p o in t c o n n e c tiv ity m a tr ix .
P o in ts ca n b e r e l a t e d to o th e r d a ta
e le m e n ts , w h o se lo c a tio n s c a n b e e i t h e r d e fin e d o r u n d efin ed , b y e ith e r
c o n n e c tiv ity c o d e s o r a c o n n e c tiv ity m a tr ix .
a r e a c e n tr o id s a s an in d e x to a r e a s .
A c a s e in p o in t i s th e u s e of
If th e a r e a s a r e d efin ed b y c o o r d in a te s ,
th e c o o r d in a te s of th e c e n tr o id s ca n r e l a t e th e m to th e a r e a s .
C o o r d in a te
p o in ts c a n a l s o b e r e l a t e d to a r e a s b y im p lic it o r e x p lic it c o n n e c tiv ity
co d es.
In e i th e r c a s e , th e m e t r i c r e l a tio n s h ip of th e p o in ts can b e u s e d
(an d f r e q u e n tly i s u se d ) a s a s u r r o g a te f o r th e m e tr ic re la tio n s h ip o f th e
a r e a s , w ith s o m e g a in in d a ta c o m p a c tio n b u t w ith th e r i s k o f lo s s of
ac cu racy .
I n a d d itio n , c e n tr o id s w ith m e tr ic o r o th e r c o d e s c a n b e
89
to p o lo g ic a lly i n t e r r e l a t e d , f o r e x a m p le b y a p o in t c o n n e c tiv ity code o r
m a tr ix , w h ic h m a y fu n c tio n a s a s u r r o g a te f o r a n a r e a c o n n e c tiv ity in d ic a to r , b u t a g a in w ith th e r i s k of lo s s o f a c c u r a c y .
A r b i t r a r y r e g u l a r a r e a s c a n b e d e fin e d b y c o o r d in a te s fix in g tw o o r m o re
p o in ts o f th e a r r a y a n d b y to p o lo g ic a lly co d in g th e r e g u l a r c e lls c o n ta in e d
in th e a r r a y (a f o r m o f d a ta c o m p a c tio n ).
B o th s e q u e n tia l d a ta g ro u p in g
a n d in v e r te d d a ta g ro u p in g of a r e a l u n its s i m i l a r in s iz e an d s h a p e a r e
co m m o n ( s e e d is c u s s io n on file s t r u c t u r e s b elo w ).
E x p lic it d a ta e le m e n t
c o n n e c tiv ity i s in h e r e n t in b o th f o r m s of to p o lo g ic a l codin g .
L in e s e g m e n ts c a n b e r e c o r d e d in a c o m p a c t f o r m of s to r a g e th a t u tiliz e s a
p o in t - o f - o r ig in c o o rd in a te fo llo w e d b y t h e i r le n g th a n d d ir e c tio n .
W ith a
p o la r c o o r d in a te s y s t e m , a n a p p ro a c h u s in g v a r i a b le - l e n g th v e c to r s c a n b e
e m p lo y e d .
W ith a n o rth o g o n a l c o o rd in a te s y s t e m , a c h a in -e n c o d in g a p p ro a c h
c a n b e u s e d to r e c o r d c h a n g e s of d ir e c tio n f r o m a s t a r t i n g po in t; it is n o t
n e c e s s a r y to s p e c if y le n g th in th i s c a s e , a s it i s im p lic it in th e d ire c tio n
c o d e s b e c a u s e o f t h e i r h ie r a r c h y of m o v e m e n t.
T h is a p p ro a c h to lin e
s e g m e n t c o m p a c tio n c o d in g w a s f i r s t e m p lo y e d in CGIS. 1 L in e s e g m e n ts
c a n b e n a m e d , an d c o n n e c tiv ity b e tw e e n lin e s e g m e n ts a n d o th e r d a ta
e le m e n ts c a n b e s e p a r a t e ly in d ic a te d , f o r e x a m p le , b y co d in g to en d p o in ts
o r to c o n tig u o u s a r e a s .
I r r e g u l a r p o ly g o n s ( a r e a s ) c a n b e n a m e d a n d th e n a m e s u s e d a s s u r r o g a te s
in s u b s e q u e n t g ro u p in g p r o c e s s e s (a s im p le f o r m of d a ta co m p actio n ).
A reas
c a n b e e n c o d e d a s p o ly g o n s m a d e up of a s e r i e s of p o in ts , o r a s a s e t of
lin e s e g m e n ts ; th i s i s th e re d u n d a n t c o n v e rs e of lin e s e g m e n ts co d ed c o n tig u o u s ly to a r e a s .
A r e a s c a n b e r e l a t e d to o th e r a r e a s b y b e in g coded
a s co n tig u o u s o r b y a c o n n e c tiv ity m a tr ix .
T h e s e e x a m p le s do n o t f o r m a c o m p le te l i s t of th e s p e c if ic n o n -g ra p h ic d a ta
f o r m a ts th a t c a n b e d e v ise d .
T h e y a r e g iv e n to i l l u s t r a t e th e ra n g e of
p o s s ib le ty p e s o f code a n d th e r a n g e o f ty p e s of s p a ti a l r e la tio n s h ip w ith in
a d a ta s e t th a t c a n b e e x p r e s s e d b y v a r io u s c o d in g f o r m s .
E x a m p le s of
1. T h e C a n a d a G e o g ra p h ic In f o rm a tio n S y s te m (T o m lin s o n , R. F . 1967).
90'
th e p o s s i b ili tie s a r e g iv e n below (F ig . 4. 5).
P u re
E x a m p le s of d a ta
E x a m p le s of d a ta
c o o rd in a te c o m p a c tio n fu n c tio n s
co n n e c tiv ity fu n c tio n s
d e fin itio n
(C o m b in ed u s e of m e tr ic & to p o lo g ic a l co d es)
P o in ts
P o in t n a m e
(ty p ic a lly a n u m b e r)
P o in t to p o in t
c o n n e c tiv ity [codeor m a tr ix ]
P o in ts r e l a te d
to a r e a s
[coderm a tr ix ]
A r b itr a r y
re g u la r
a re a s
G rid c e ll n am e
S e q u e n tia l coding
In v e rte d c o d in g , e tc .
L in e
s e g m e n ts
S eg m en t n am e
V a r ia b le v e c to r co d in g
U nit v e c to r co d in g
(ch ain coding)
L in e s e g m e n ts
to end p o in ts
L in e s e g m e n ts
to a r e a s
I r re g u la r
p o ly g o n s
(area s)
A re a nam e
A r e a s m a d e up of p o in ts
A r e a s m a d e up of lin e
s e g m e n ts
A r e a s to a r e a s
[coderm a trix ]
F ig . 4. 5.
L in e s e g m e n t
b o u n d a ry c h a in s
N am es re fe rrin g
to e x te r n a l
m e t r i c in d e x
T o p o lo g ic a lly
u n r e la te d
nam es
T o p o lo g ic a lly
r e l a te d
nam es
R ange of c o d in g r e l a te d to e x p r e s s io n of s p a ti a l r e la tio n s h ip s
w ith in a d a ta s e t.
I t c a n b e s e e n f r o m th e d ia g ra m th a t th e b a s ic f o r m a t of n o n - g r a p h ic d a ta is
d e c id e d b y th e ty p e of r e a l - w o r l d d a ta e le m e n t b e in g e n c o d e d (p o in t, lin e ,
a r e a , o r a r b itr a r y a re a ).
T h e s im p l e s t f o r m of n o n - g r a p h ic s to r a g e u s e s
p u r e c o o rd in a te d e fin itio n a lo n e , o r to p o lo g ic a l r e f e r e n c e to an e x te r n a l
in d e x .
T h e c e n tr a l p a r t of th e d ia g r a m , h o w e v e r, in d ic a te s th e a r e a w h e re
c a r e f u l c h o ic e of f il e s t r u c t u r e c a n b e n e fit th e s u b s e q u e n t e a s e o f r e t r i e v a l
o f th e d a ta , c a n allow m o d a l ch a n g e of d a ta to b e a tte m p te d , a n d , in s o m e
i n s ta n c e s , c a n re d u c e s to r a g e r e q u i r e m e n t s .
F I L E S TR U C TU R ES F O R CODED N O N -G R A PH IC S P A T IA L D ATA
T h e p h y s ic a l a rr a n g e m e n t of a n y s u b s ta n tia l c o lle c tio n of d a ta in an y f o r m a t,
n o n -g r a p h ic o r g r a p h ic , a f fe c ts th e e a s e w ith w h ic h i t m a y s u b s e q u e n tly b e
e x a m in e d , c o r r e l a te d , an d u n d e rs to o d .
T h e r a n g e of d a ta a r r a n g e m e n t ty p e s
th a t c a n b e e m p lo y e d i s d ir e c tl y r e l a t e d to th e p h y s ic a l a n d e c o n o m ic c o n ­
s t r a i n t s of h a n d lin g d a ta in th e c h o s e n s to r a g e m e d iu m .
T h e c h o ic e o f d a ta
a r r a n g e m e n t w ith in th a t r a n g e is ( o r sh o u ld be) b a s e d on th e m a n n e r in
91
w h ic h th e d a ta a r e s u b s e q u e n tly to b e m a n ip u la te d .
T h e p h y s ic a l c h a r a c t e r i s t i c s of s to r a g e m e d ia re a d a b le b y a c o m p u te r (su ch
a s c a r d s , t a p e s , d is k s , c o r e , a n d c e lls ) an d th e e le c tr o n ic c a p a b ility of
e x is tin g c o m p u te r s to r e a d a n d h a n d le d a ta s o s to r e d a r e w e ll-d o c u m e n te d
a s p e c t s of c o m p u te r d e s ig n .
T h e r e s u lt in g ra n g e of d a ta a r r a n g e m e n t
ty p e s is d is c u s s e d b r ie f ly b elow s o th a t th e file s tr u c t u r e s 1 c u r r e n t ly u s e d
to h a n d le m a p p e d a n d r e l a t e d lo c a tio n - s p e c if ic d a ta c a n b e v ie w e d in co n te x t.
T h e ti m e a n d c o s t in v o lv e d in r e a d in g a n d c o r r e l a ti n g a c o lle c tio n of
c o m p u te r - s to r e d d a ta a r e a ff e c te d b y : th e s e q u e n c e in w hich th e d a ta a r e
s to r e d (file s e q u e n c in g ); th e m a n n e r of lin k in g and th e d e g re e to w h ic h it is
p o s s ib le to e s ta b lis h lin k s b e tw e e n d a ta o r s e t s of d a ta (file lin k a g e ); th e
m a n n e r in w h ic h e a c h d a ta e le m e n t i s d e s c r ib e d in th e file (file r e c o r d
la y o u t); a n d th e in fo r m a tio n c o n te n t of th e f ile (file in fo rm a tio n c o n ten t).
O nly a li m it e d s e r i e s of a p p r o a c h e s c a n b e u s e d w ith in e a c h o f th e s e fo u r
a s p e c t s o f f il e s t r u c t u r e .
A lth o u g h t h e r e i s no a c c e p te d o r d in a l s c a l e o f
c o m p le x ity o f o v e r a l l f i l e s t r u c t u r e , th e s im p le s t f il e s tr u c t u r e s te n d to u s e
e l e m e n t a r y a p p r o a c h e s in th e s e f o u r c a te g o r ie s an d th e m o s t co m p le x f ile
s t r u c t u r e s e m p lo y o n e o r m o r e of th e a d v a n c e d a p p ro a c h e s .
A b r ie f
d e s c r i p tio n of th e v a r i o u s a p p r o a c h e s fo llo w s.
F i l e S eq u en c in g
1) S e q u e n tia l
2) In d e x e d S e q u e n tia l
3) D ir e c t A c c e s s
A s e q u e n tia l a r r a n g e m e n t i s th e s im p l e s t of a ll.
E a c h d a ta e le m e n t h a s a
d ir e c t a n d s p e c if ic r e l a ti o n s h i p to th e o n e s s to r e d im m e d ia te ly b e f o r e an d
a f t e r i t , an d th i s r e l a ti o n s h i p i s s p e c ifie d b y th e p o s itio n of th e d a ta e le m e n t
in th e s e q u e n c e .
I t m a y b e a r g u e d th a t th e lo w e s t f o r m of s e q u e n tia l
a r r a n g e m e n t i s one w h e r e th e d a ta e le m e n ts d e lib e r a te ly h a v e no m a th e m a tic a l r e l a ti o n s h i p to e a c h o th e r (th a t i s , n o m in a l sc a lin g ).
T h e v a r io u s
f o r m s of o rd in a l s c a lin g ( p a r t ia l o r d e r in g , w eak o r d e rin g , an d c o m p le te
o r d e r i n g ), in t e r v a l s c a lin g , a n d r a t i o s c a lin g f o r m in c r e a s in g ly s o p h is tic a te d
le v e ls of s e q u e n tia l r e l a ti o n s h i p s .
M u ltid im e n sio n a l s c a lin g ca n n o t be
c o n v e n ie n tly a c c o m m o d a te d in a s im p le li n e a r a r r a n g e m e n t w ith o u t t r a n s f o r m a tio n .
If a n a r r a y of g r id s q u a r e s w e r e s e q u e n tia lly f ile d , th e y w o u ld
b e s to r e d s t r i p b y s t r i p .
1. F o r th e p u r p o s e s o f th i s d is c u s s io n , a " file " is ta k e n to b e a n a r r a n g e d
s e t of d a ta , a n d f ile " s t r u c t u r e " r e f e r s to th e m a n n e r in w h ich th e d a ta
a r e a rran g e d .
92
A n in d e x e d s e q u e n tia l a r r a n g e m e n t im p lie s a s e q u e n tia l s to r a g e r e l a ti o n s h i p
b e tw e e n d a ta e le m e n ts , b u t ad d s th e f a c i li ty of a r e l a t e d in d e x .
If, fo r
e x a m p le , s o m e d a ta e le m e n ts in th e s e q u e n c e w e r e m is s in g , th e r e l a tio n s h ip
b e tw e e n a d ja c e n t e le m e n ts in th e f ile c o u ld b e d e te r m in e d f r o m th e in d e x .
F o r e x a m p le , if an a r r a y of g r id s q u a r e s w e r e in d e x e d b y g r id c e n tr o id
c o o r d in a te s , th e r e s u l t w o u ld b e a n in d e x e d s e q u e n tia l f ile .
A d ir e c t a c c e s s a r r a n g e m e n t d o e s n o t r e q u i r e an y r e la tio n s h ip to e x is t
b e tw e e n a d ja c e n t d a ta e le m e n ts in s to r a g e (an a r g u m e n t a g a in s t n o m in a l
s c a l in g a s th e lo w e s t f o r m of s e q u e n tia l a r r a n g e m e n t) .
In th i s c a s e ,
h o w e v e r, th e d a ta e le m e n ts a r e p la c e d in a lo g ic a l s e q u e n c e a c c o r d in g to
a r a n d o m iz in g f o r m u l a a n d th e r e l a tio n s h ip b e tw e e n d a ta e le m e n ts i s d e t e r m in e d e n t ir e l y f r o m th e r a n d o m iz in g f o r m u la an d n o t f r o m t h e i r p o s itio n in
th e s e q u e n c e of d a ta e le m e n ts .
A co m m o n u s e of a r a n d o m iz in g f o r m u l a i s
know n a s " k e y tr a n s f o r m a tio n " o r " h a s h co d in g ".
T h e n a m e o f e a c h d a ta
e le m e n t to b e s to r e d , f o r e x a m p le , th e v a lu e of v a r ia b le A a t g r id lo c a tio n
23, 64 (i. e . , A. 23, 64) is t r a n s f o r m e d in to a n u m b e r c a lc u la te d f r o m th e
b in a r y f o r m of th e e x p r e s s io n A , 23, 64, u s in g a g iv e n fo r m u la .
The
r e s u lt in g n u m b e r i s u s e d a s an " a d d r e s s " in c o m p u te r s to r a g e a t w h ic h a r e
s t o r e d th e d a ta d e s c r ib in g th e a c tu a l v a lu e of A a t g r id lo c a tio n 2 3 , 64.
Even
w ith s o m e a d d itio n a l c o d e s to allow f o r r e a s s ig n m e n t of d u p lic a te d a d d r e s s e s ,
s p a r s e d a ta c o n te n ts of a n a r r a y c a n b e s t o r e d in m u c h l e s s s p a c e th a n
w o u ld b e ta k e n b y a c o m p le te a r r a y , a n d th e a d d r e s s e s o f s p e c if ic d a ta
i t e m s c a n b e d e te r m in e d th ro u g h c a lc u la tio n b y th e r a n d o m iz in g f o r m u la .
F i l e L in k a g e
A) F ile d a ta o rg a n iz a tio n
1) Sequential data grouping
2) I n v e r te d d a ta g ro u p in g
3) L i s t - s t r u c t u r e d d a ta g ro u p in g
4) V a lu e - l is t- s tr u c t u r e d d a ta o r
C r o s s - l i s t - s t r u c t u r e d d a ta
B) F ile p o in te r s
1) None
2) I n tr a - d a ta - e le m e n t p o in t e r s
a) E x te r n a l d ir e c to r y
b) I n te r n a l d ir e c to r y
c) In te g r a te d p o in te r s
3) I n tr a - f i le p o in te r s
a) E x te r n a l d ir e c to r y
b) I n te r n a l d ir e c to r y
c) In te g r a te d p o in te r s
4) I n te r - f i le p o in te r s
a) E x te r n a l d ir e c to r y
b) I n te r n a l d ir e c to r y
c) I n te g ra te d p o in te r s
93
T h e p u r p o s e of f il e lin k a g e te c h n iq u e s i s to allo w o r a i d th e g ro u p in g an d
r e t r i e v a l of s u b s e ts of d a ta c o n ta in e d in a f il e , o r in m u lti- f ile c o lle c tio n s
o f d a ta , w ith o u t r e a d in g an d p r o c e s s in g th e e n t ir e d a ta s to r e .
O ne o b v io u s
a p p ro a c h to th i s t a s k i s to d e te r m in e in a d v a n c e a l l th e n e e d e d s u b s e ts of
d a ta a n d to c r e a te s e p a r a t e s m a l l f il e s f o r th e m .
T h is i s th e b a s ic c o n -
c e p t b e h in d f il e d a ta o rg a n iz a tio n .
A n o th e r a p p ro a c h i s to in c lu d e in th e o r ig in a l f i l e o r f i l e s a s e t o f " p o in te r s " 1
le a d in g f r o m a p p r o p r ia te d a ta e le m e n ts to o th e r d a ta e le m e n ts w ith w h ich
th e y m a y e v e n tu a lly b e g ro u p e d .
p o in te rs .
T h is i s th e b a s i c r a tio n a le b e h in d f ile
B o th a p p r o a c h e s c a n b e u s e d w ith in th e s a m e d a ta s e t.
T h e s i m p l e s t f o r m of file d a ta o r g a n iz a tio n i s s e q u e n tia l d a ta g ro u p in g .
No
s u b s e t g ro u p in g i s a tte m p te d , an d th e o n ly s u b s e ts th a t ca n b e c o n v e n ie n tly
e x t r a c te d a r e p a r t s of th e o r ig in a l f ile in t h e i r o r ig i n a l s e q u e n c e , s u c h a s
th e f i r s t h a lf, th e m id d le th i r d , o r th e l a s t q u a r t e r .
I n v e r te d d a ta g ro u p in g
i s th e f i r s t a tte m p t a t re o r g a n iz in g th e o r ig i n a l f ile .
I t i s th e e le m e n ta r y
c o n c e p t of m a tr ix in v e rs io n .
D a ta in a n a r r a y of g r id s q u a r e s w o u ld b e
s t o r e d c o lu m n b y co lu m n r a t h e r th a n ro w b y ro w , to av o id p r o c e s s in g th e
w h o le f il e in o r d e r to e x a m in e th e d a ta f r o m o n e c o lu m n o n ly .
T h is s t r a i g h t -
f o r w a r d a p p r o a c h b e c o m e s ex p e n siv e if th e d a ta c o n ta in e d in th e a r r a y a r e
sp a rse .
T o o v e rc o m e th i s p ro b le m , l i s t s t r u c t u r e s a r e u s e d w h ic h s im p ly
l i s t th e d a ta in th e s u b s e ts r e q u ir e d an d s t o r e th e m in th a t m a n n e r .
A
v a l u e - l i s t s t r u c t u r e is e m p lo y e d w hen e a c h d a ta r e c o r d c o n ta in s a n u m b e r
o f v a l u e s , a n d s u b s e ts of s e le c te d v a lu e s a r e r e q u i r e d a s w e ll a s s u b s e ts
of th e d a ta r e c o r d s th a t c o n ta in th o s e v a lu e s .
S im ila r ly , l i s t s c a n b e
c r e a t e d th a t g ro u p s p e c ific d a ta e le m e n ts f r o m a v a r i e ty o f o th e r l i s t s ;
th i s p r o v id e s a c r o s s - l i s t s tr u c t u r e .
A ll o f th e s e f o r m s of f il e d a ta o rg a n iz a tio n c a n b e a c h ie v e d b y u s in g p o in te r s ;
in f a c t , l i s t s t r u c t u r e s (A3 an d A4 in th e s u b s e c tio n h e a d in g above) a r e n ot
o fte n fo u n d w ith o u t th e m .
P o in te r s ca n b e c o n ta in e d in a l i s t th a t is
e x t e r n a l to th e s y s t e m ( e x te rn a l d ir e c to r y ) , o r a l i s t th a t i s in t e r n a l to th e
s y s t e m a n d h e n c e p a r t of th e f il e (in te r n a l d ir e c to r y ) , o r th e y c a n b e
a c tu a lly a tta c h e d to th e d a ta e le m e n ts th e m s e lv e s (in te g r a te d p o in te r s ) .
I n tr a - d a ta - e le m e n t p o in te r s a r e th o s e e m p lo y e d to lin k a s e r i e s of ite m s
1 . P o i n t e r s ca n ta k e s e v e r a l f o r m s , th e m o s t co m m o n of w h ich is a code
fo llo w e d b y th e s to r a g e " a d d r e s s " of th e n e x t d e s ir e d d a ta e le m e n t.
94
of d a ta th a t to g e th e r m a k e up one d a ta e le m e n t (fo r e x a m p le , th e lin k a g e s
b e tw e e n lin e s e g m e n ts th a t to g e th e r m a k e up a s p e c ific polygon).
I n tr a - f i le
p o in t e r s a r e th o s e e m p lo y e d to co n n e c t s u b s e ts of d a ta w ith in one f ile (su ch
a s th e lin k a g e s th a t e s ta b lis h a d ja c e n c y b e tw e e n p o ly g o n s on a m ap).
I n t e r - f i l e p o in t e r s a r e th o s e u s e d f o r m u lti-file in d e x in g (fo r e x a m p le , to
c o n n e c t d if f e r e n t d a ta ty p e s ) .
T h e l a s t c a te g o ry of p o in te r p e r m its m o r e
e f fic ie n t u s e of s u b s e c tio n s o f d a ta f o r s p e c if ic p u r p o s e s an d m o r e e ffic ie n t
u s e of s o m e ty p e s of c o m p u te r h a r d w a r e th a t h a n d le s m a l l b u n d le s o f d a ta
a s c h e a p ly a s in d iv id u a l d a ta e le m e n ts .
T h e s e n s ib le u s e of v a r io u s ty p e s of f il e se q u e n c in g a n d f il e lin k a g e s
in c r e a s e s th e fle x ib ility of a f il e of d a ta a n d d e c r e a s e s th e tim e f o r d a ta
r e t r i e v a l in r e s p o n s e to an e n q u iry .
T h e s e b e n e fits a r e g a in e d a t th e
e x p e n s e of u s in g a d d itio n a l s to r a g e s p a c e a n d in c r e a s in g th e tim e n e e d e d
in i tia lly to e s ta b lis h a n d s u b s e q u e n tly to a m e n d th e f ile .
F ile R e c o rd L ayout
1) F ix e d F o r m a t
2) V a ria b le F o r m a t
3) M ixed F o r m a t
P r a c t i c a l l y a l l c o m p u te r s to r a g e s y s t e m s a r e l i n e a r ; one s to r a g e lo c a tio n
c o m e s a f t e r a n o th e r a n d no new o n e s m a y b e in s e r t e d b etw e en th e o r ig in a l
o nes.
T h e s i m p l e s t ty p e o f r e c o r d la y o u t is th u s one w h e re th e f o r m a t of
e a c h d a ta e le m e n t c a n b e d e te r m in e d in ad v a n c e a n d w h e re fix e d b lo c k s o r
s t a n d a r d - s i z e d u n its of s to r a g e a r e a llo c a te d f o r e a c h d a ta e le m e n t.
Such
r e c o r d s a r e s a id to b e in a fix e d f o r m a t.
A p a rt f r o m th e o b v io u s a d v a n ta g e s of u n ifo rm ity , th e v a lu e of f ix e d - fo r m a t
d a ta i s a p p a r e n t in a l l of th e d a ta s t r u c t u r e s d e s c r ib e d ab o v e , w h e re th e
p o s itio n of a d a tu m in a f il e c a r r i e s a g r e a t d e a l of m e a n in g an d c a n id e n tify
th e d a tu m .
T h e d iffic u lty a r i s e s w h en d a ta in a fix e d f o r m a t s tr u c t u r e a r e
s p a r s e o r w h en , b y th e n a tu r e of th e d a ta , a fix e d f o r m a t i s im p r a c tic a b le .
A r e a l d a ta w ith b o u n d a rie s d e s c r ib e d b y lin e s e g m e n ts is ju s t o n e ex a m p le.
F o r s u c h c a s e s , v a r i a b le - f o r m a t d a ta c a n b e e m p lo y e d , b u t a d d itio n a l d a ta
(p o in te rs ) a r e n e e d e d to in d ic a te th e b e g in n in g , s iz e , o r en d o f a r e c o r d ,
o r to in d ic a te th e s iz e of v a r i a b le - s iz e d d a ta a r r a y s .
W h e re th e d a ta
c o n te n t of e a c h r e c o r d i s v a r i a b le (v a r i a b le d a ta c o n te n ts ), a d ir e c to r y of
95
th e c o n te n ts m u s t b e p ro v id e d in a s e p a r a t e p a r t of th e c o m p u te r o r co d ed
w ith in e a c h r e c o r d it s e l f , s o th a t th e v a r io u s c a te g o r ie s o f d a ta a t d iffe re n t
p la c e s in th e v a r i a b le r e c o r d s c a n b e lo c a te d , a d d e d to , o r d e le te d .
M ixed
f o r m a ts m a y b e u s e d in la r g e f i l e s , to ta k e a d v a n tag e of fix e d f o r m a ts f o r
s o m e p a r t s o f g r o u p in g a n d r e t r i e v a l w h ile r e ta in in g v a r ia b le f o r m a ts to
a c c o m m o d a te v a r i a b le f o r m s o f d a ta .
In e v ita b ly , th e in te r a c tio n of th e
tw o r e q u i r e s a d d itio n a l s e t s o f p o in t e r s , s to r a g e s p a c e , an d p ro g ra m m in g .
F i l e In fo rm a tio n C o n te n t
T h e s t r u c t u r e of a n y f il e i s o b v io u s ly in flu e n c e d b y th e f o r m a t o f th e s o u r c e
d a ta i t h a s to h a n d le (s e e c o d e d n o n - g r a p h ic d a ta f o r m a ts , a b o v e ).
A
s e c o n d in flu e n c e on th e u tility of th e file s t r u c t u r e i s i t s c a p a c ity to a c c e p t
r e l a t e d o r s u m m a r y d a ta w h ic h m a k e it u n n e c e s s a r y t o r e p e a t c a lc u la tio n s
o n th e o r ig i n a l d a ta s e t (fo r e x a m p le , th e a r e a o r th e c e n tr o id o f p o ly g o n s).
T h e s e n s ib le u s e of f ile r e c o r d la y o u t a n d a d d itio n a l f il e in f o rm a tio n c o n ten t
c a n d e c r e a s e th e v o lu m e of s to r a g e r e q u i r e d f o r s p a r s e d a ta , a t a c o s t of
in c r e a s in g th e c o m p le x ity o f th e f ile an d h e n c e th e p r o c e s s in g c o s ts .
(W h ere d a ta s u b s e q u e n tly b e c o m e d e n s e , b o th s to r a g e an d p r o c e s s in g c o s ts
a r e in c r e a s e d . ) T h e t a s k th a t f a c e s th e f il e d e s ig n e r i s to a c h ie v e a
b a la n c e b e tw e e n s to r a g e v o lu m e a n d th e am o u n t of p r o c e s s in g n ee d ed .
R E L A T IO N S H IP B E T W E E N T Y P E O F STO RA G E FO R M A T F O R
N O N -G R A P H IC S P A T IA L DATA AND CU R R EN T SYSTEM S F O R
HAN D LIN G S P A T IA L DATA
T h e u n d e r ly in g th e m e of th e a b o v e d is c u s s io n i s th a t th e f o r m a t, file
s t r u c t u r e , a n d u ti lit y o f a s t o r e of n o n - g ra p h ic d a ta d ep e n d to a g r e a t
e x te n t o n th e f o r m a t o f th e r e a l - w o r l d d a ta e le m e n ts to b e r e p r e s e n t e d in it.
W hen v a r i o u s f o r m a ts of r e a l - w o r l d d a ta m u s t b e in c lu d e d in o ne s y s te m ,
it i s , of c o u r s e , p o s s ib le to c o d e th e m a n d co m b in e th e m in a v a r i e ty of
w ays.
W hen t h e r e i s o n ly o n e ty p e of f o r m a t of r e a l - w o r l d o r c o d e d d a ta
e le m e n t, t h e r e a r e in h e r e n t lim ita tio n s on th e ty p e s o f o p e r a tio n s th a t
c a n b e p e r f o r m e d on th e r e s u lt in g s t o r e of d a ta .
w ith p o in t d a ta .
T h is c a n b e il lu s tr a t e d
96
C o o rd in a te
p o in ts
P o ly g o n
d efin in g p o in ts
F ig . 4 . 6.
O p e r a tio n s p o s s ib le o n s p a ti a l -data co d e d a s c o o r d in a te p o in ts .
T h e d ia g r a m (F ig . 4 . 6) sh o w s th e o p e r a tio n s p o s s ib le on a n o n - g r a p h ic
s t o r e of s p a ti a l d a ta c o d e d a s c o o rd in a te p o in ts .
T h e p o in ts c a n b e a g g r e -
g a te d in to c o a r s e r g r id s , c a lc u la tio n s c a n b e c a r r i e d out on d e n s ity
(in c lu d in g c o n to u rin g ), d is ta n c e , a r e a , an d d ir e c tio n , an d b o u n d a ry o p e r a tio n s c a n b e p e r f o r m e d (fo r e x a m p le , w ith in c i r c l e s , r e c t a n g le s , o r p o ly g o n s).
A b a s ic li m ita tio n o f th e f o r m a t of n o n - g ra p h ic s to r a g e u s in g
n o th in g b u t c o o rd in a te p o in ts i s th a t o n ly r e l a ti o n s h i p s d e r iv e d f r o m p o in tt o - p o i n t d is ta n c e c a lc u la tio n s c a n b e a d e q u a te ly r e n d e r e d .
W ith o u t a d d itio n a l
d a ta d e r iv e d f r o m o th e r d a ta f o r m a t s , th e r e i s n o w a y of in f e r r i n g in f o r m a tio n ab o u t a d ja c e n c y o r a c c e s s i b ili ty s u c h a s c o u ld b e d e te r m in e d f r o m
n e tw o rk , g r id , o r b o u n d a ry (web) f o r m a ts ; th e s e a r e n o t in h e r e n t in th e
p o in t s y s te m .
T h e ty p e of li m ita tio n a p p lie s to s o m e d e g re e to a l l in d iv id u a l d a ta f o r m a ts ,
a n d h a s p a r t i c u l a r im p a c t on th e a b ility to t r a n s f o r m one ty p e of d a ta to
a n o th e r.
F o r e a c h ty p e of r e a l - w o r l d d a ta e le m e n t th e r e i s s t i l l an o p tim u m
c o d e d n o n - g r a p h ic f o r m a t (p o in ts a s p o in ts , li n e s a s li n e s , and s o f o rth ).
T r a n s f o r m a tio n to o th e r f o r m a ts is p o s s ib le in s o m e in s ta n c e s , b u t in o th e r s
i t r e q u i r e s d a ta re d u c tio n .
In th i s e a r l y s ta g e of d ev e lo p m en t of c o m p u te r -
97
a id e d s y s t e m s f o r h a n d lin g s p a ti a l d a ta , t h e r e h a s b e e n a s tr o n g (an d p e r h a p s
u n d e rs ta n d a b le ) te n d e n c y to av o id th e c o m p lic a tio n s of c r o s s - f o r m a t
lin k a g e s b u t r a t h e r to d ev e lo p s y s te m s p r i m a r i l y d e s ig n e d to h a n d le s p e c if ic ,
in d iv id u a l f o r m a ts of d a ta .
T h e r e la tio n s h ip b e tw e e n r e a l - w o r l d d a ta e l e ­
m e n ts a n d c o d e d n o n - g r a p h ic s to r a g e f o r m a ts w ith e x a m p le s o f c u r r e n t
s y s t e m s i s sh o w n in th e d ia g r a m (F ig . 4. 7).
R e a l-w o rld d a ta
e le m↓e n t→
P o in t
L in e
A rea
C o d ed
s to r a g e f o r m a t
(unless data
LU N R, O ZA RKS, e tc .
c o lle c te d
by s a m e
SYM A P, MIADS, e tc .
a r e a u n its)
A rb itra ry
re g u la r a re a
(e. g . , g rid )
O p tim a l
P o in t
L in e s e g m e n t
T y p ic a l c u r r e n t
g e o g r a p h ic a l in f o r ­
m a tio n s y s te m s
F R IS , GRDSR, e tc .
O p tim a l
D IM E, SACS, e tc .
M A P /M O D E L , PIO S
P o ly g o n
O p tim a l
CGIS
F ig . 4. 7.
R e la tio n s h ip b e tw e e n r e a l - w o r l d d a ta e le m e n ts an d co d ed
n o n - g r a p h ic s to r a g e fo r m a ts .
E a c h of th e s e c a te g o r ie s of s to r a g e f o r m a t, th a t i s , a r b i t r a r y r e g u l a r a r e a s ,
p o in ts , lin e s e g m e n ts , a n d p o ly g o n s, w ill b e e x a m in e d in tu r n b elo w .
T h e ir
c h a r a c t e r i s t i c s w ill b e il l u s t r a t e d b y e x a m in in g one o r m o r e s p e c if ic s y s te m s
w ith in e a c h c a te g o ry , s o th a t th e p r a c t ic a l, a s w e ll a s th e th e o r e ti c a l,
c o n s tr a in ts a n d c a p a b ilitie s in h e re n t in e a c h s to r a g e fo r m a t ca n b e s e e n .
1. LU N R - N ew Y o rk S ta te L a n d U se an d N a tu r a l R e s o u r c e s s y s te m ; MIADS U. S. F o r e s t r y S e rv ic e s y s te m ; SYM AP - S y n a g ra p h ic C o m p u te r G ra p h ic s ,
H a r v a r d U n iv e r s ity ; F R IS - S w edish C e n tr a l B o a rd f o r R e a l E s ta te D ata
s y s te m ; GRDSR - G e o g r a p h ic a lly 'R e f e r e n c e d D a ta S to ra g e a n d R e tr ie v a l
s y s te m , S ta t is tic s C an a d a; DIM E - D ual In d e p e n d e n t M ap E n c o d in g s y s te m ,
U. S. B u r e a u of C e n s u s ; SACS - S tr e e t A d d r e s s C o n v e rs io n S y ste m , U rb a n
D a ta C e n te r , S e a ttle .
98
A R B IT R A R Y R E G U L A R -A R E A C A TEG O RY O F SYSTEM S
It ca n b e s e e n f r o m th e d ia g r a m (F ig . 4. 7) th a t th e c h o ic e o f a s to r a g e f o r m a t
u s in g a r b i t r a r y r e g u l a r a r e a s (ty p ic a lly , a g rid ) f o r r e a l - w o r l d d a ta e le m e n ts
im p lie s s o m e d e g r e e of d a ta re d u c tio n , u n le s s th e s o u r c e d a ta e le m e n ts a r e
h o m o g e n e o u s ly (evenly) d is tr ib u te d th ro u g h o u t e a c h a r b i t r a r y a r e a an d u n le s s
c h a n g e s in d a ta v a lu e s o c c u r o n ly a t th e b o u n d a r ie s of th e a r b i t r a r y a r e a s .
T h e m e th o d h a s th e a d v a n ta g e of b e in g a s im p le a p p ro a c h to d a ta s to r a g e ,
a t th e e x p e n s e of s o m e in fo rm a tio n re d u c tio n .
A lthough c o n s id e r a b le
(u s u a lly m a n u al) e f f o r t i s in v o lv e d in re w o rk in g e x is tin g d a ta s e t s to c o n f o r m
to r e g u l a r - s h a p e d " p ig e o n h o le s " , it i s a s im p le c o m p u ta tio n a l t a s k to s t o r e
th e r e s u l t s a n d s u b s e q u e n tly r e t r ie v e o r d is p la y th e m .
If th e a r b i t r a r y a r e a s a r e l a r g e c o m p a re d w ith th e s iz e a n d s p a ti a l c o m p le x ity
of th e d a ta e le m e n ts th e y r e p r e s e n t , th e coding f r e q u e n tly c r e a t e s a s p u r io u s
h o m o g e n e ity , d e g r a d e s lo c a tio n a l p r e c is io n , a n d im p o s e s a n u n r e a l f o r m a t
on th e s o u r c e d a ta .
If th e a r b i t r a r y a r e a s a r e s m a l l c o m p a r e d w ith th e
d a ta e le m e n ts th e y r e p r e s e n t , th e s e e ff e c ts a r e m in im iz e d .
A w id e v a r i e ty
of s y s t e m s h a s b e e n d e v e lo p e d u s in g th e a r b i t r a r y r e g u l a r - a r e a s to r a g e
f o r m a t, a n d th e y r a n g e f r o m th o s e in itia lly d e s ig n e d to a c c e p t c o m p a r a tiv e ly
la r g e c e lls r e l a t i v e to th e d a ta b e in g s to r e d , w h ich w ill b e t e r m e d
Type 1
s y s t e m s , to s y s t e m s w h o se m a n ip u la tiv e fu n c tio n s a s s u m e a s m a l l c e ll s iz e
r e l a ti v e to th e s o u r c e d a ta e le m e n ts b e in g s to r e d , to b e te r m e d T y p e 2.
s y s t e m s (F ig . 4 . 8).
L a rg e
T
ype1m a n ip u la tio n
c a pab iliti e s
C e ll
s iz e
Type2man ip u la tio n
c a p a b ilitie s
S m a ll
S o u rc e d a ta e le m e n t c h a r a c te r is tic s
L a rg e
S m all
R e g u la r d is tr ib u tio n
I r r e g u l a r d is tr ib u tio n
F ig . 4 . 8.
T y p e s of m a n ip u la tio n c a p a b ility in s y s t e m s b a s e d o n s to r a g e
f o r m a ts u s in g a r b i t r a r y r e g u l a r a r e a s a s a fu n c tio n o f c e ll
s iz e a n d c h a r a c t e r i s t i c s of s o u r c e d a ta e le m e n ts .
99
In h e r e n t in fo rm a tio n l o s s g e n e r a lly d e c r e a s e s a lo n g th e d ia g o n al in th e
d ia g r a m (F ig . 4 .8 ) .
W ith in s p e c if ic s y s t e m s , h o w e v e r, th e d e g r e e of
d a ta r e d u c tio n i s a fu n c tio n of th e m ix tu re of c h a r a c t e r i s t i c s o f th e d a ta
e le m e n ts b e in g s to r e d .
T h e r e l a ti o n s h i p b e tw e e n m a n ip u la tiv e fu n c tio n s
a n d th e r a t io of c e ll s iz e to d a ta e le m e n t s iz e i s s im p lifie d , b u t th i s a llo w s
a g e n e ra l g ro u p in g in to tw o b r o a d c a te g o r ie s of s y s t e m s f o r d e s c r ip tiv e
p u rp o ses.
A r b i t r a r y R e g u l a r - A r e a S y s te m s - T y p e 1
T h e f i r s t c a te g o ry (T ype 1 in F ig . 4. 8) is a ty p e o f d a ta s t r u c t u r e th a t h a s
b e e n a d o p te d f o r a n u m b e r of a d m in is tr a tiv e u n its in v a r io u s c o u n tr ie s .
In
N o rth A m e r ic a , f o r e x a m p le , th e ty p e of s to r a g e f o r m a t u s in g a r b i t r a r y
r e g u l a r a r e a s i s u s u a lly a g r id .
T h e s iz e o f th e g r id S q u a re em p lo y ed
v a r i e s f r o m 1 /8 m ile s q u a r e in Illin o is (NARIS s y s t e m 1) a n d M in n eso ta
(M in n e s o ta L a k e s h o re D e v e lo p m e n t S tudy2) to 500 m s q u a r e in p a r t s of
O n ta r io , C a n a d a ( E r i e P r o j e c t 3) , 1 km 2 in M a s s a c h u s e tts (C o m p re h e n s iv e
L a n d U se In v e n to ry P r o j e c t 4) a n d D e la w a re C o u n ty , P e n n s y lv a n ia
(D e la w a re C o u n ty I n f o rm a tio n S y s te m 5) , a n d 10 m i le s s q u a r e in th e O z a rk s
r e g io n (C o m p o site M apping S y s te m 6).
O ne ty p ic a l e x a m p le o f th e f i r s t
c a te g o r y i s LU N R ,7 th e L a n d U se a n d N a tu r a l R e s o u r c e s in v e n to r y of
New Y o rk S ta te , w h ich e m p lo y s a 1-k m 2 g r id s q u a r e .
T h e LU N R s y s te m
w ill b e u s e d to i l l u s t r a t e th e p r o b le m s an d p o te n tia ls of th i s c a te g o r y of
s to r a g e f o r m a t b e c a u s e it is a s tr a i g h tf o r w a r d e x a m p le o f th e g e n r e w h ich
h a s b e e n fu lly d e v e lo p e d in t e r m s of th e o r ig in a l o b je c tiv e s o f i t s d e s ig n e r s .
I t is q u ite w e ll d o c u m e n te d a n d h a s b e e n in e x is te n c e f o r a s u ffic ie n t tim e
( s in c e 1969) to allow a p r e l im i n a r y a s s e s s m e n t of i t s c a p a b ilitie s .
LUNR S y ste m - E x a m p le of T y p e 1 of th e A r b i t r a r y R e g u la r - A r e a C a te g o ry
T h e a i m of th e LUNR8 p r o je c t w a s to p ro d u c e an in v e n to r y o f th e p r e s e n t
la n d u s e s an d c e r t a i n e n v ir o n m e n ta l lin e an d p o in t a t tr ib u t e s in New Y o rk
S ta te .
T h e d a ta s o u r c e s a v a ila b le to th e p r o je c t w e r e a e r i a l p h o to g ra p h s
(1 :2 4 ,0 0 0 ) s u p p le m e n te d b y e x is tin g m a p s , r e p o r t s
p u b lic a g e n c y r e c o r d s , a n d d ir e c t f ie ld o b s e rv a tio n .
a n d d ir e c to r ie s ,
T h e d a ta e le m e n ts
id e n tifie d w e r e p lo tte d on 7 - 1 /2 m in u te s e r i e s of to p o g ra p h ic b a s e m ap s
(1 :2 4 ,0 0 0 ) of th e U n ite d S ta te s G e o lo g ic a l S u rv e y (USGS).
T h e f i r s t s te p
1. U n iv e r s ity of I llin o is 1970. 2. B o r c h e r t 1969. 3. B r u e r 1967, P h ilb r ic k
1967. 4. V o g t, I v e r s a n d A s s o c ia te s 1966. 5. D e la w a re C ounty P la n n in g
C o m m is s io n 1970. 6. U. S. D ep t. of C o m m e r c e 1967. 7. H a rd y e t a l. 1971a.
8. H a rd y e t a l. 1971b.
100
in th e o v e r a l l p r o je c t w a s th u s to e s ta b lis h a to t a ll y g ra p h ic s to r a g e f ile .
T h e g r a p h ic d a ta a r e c o n v e rte d to a n o n -g ra p h ic f o r m a t u s in g v e r y s im p le
c o m b in e d m e t r i c a n d to p o lo g ic a l c o d e s f o r an a r r a y o f g r id s q u a r e s 1 s u p e r im p o s e d o n th e USGS b a s e m a p s.
U n iv e r s a l T r a n s v e r s e M e r c a to r (UTM)
c o o r d in a te p a i r s ta k e n f r o m th e c o r n e r s of e a c h b a s e m a p m e tr ic a lly d efin e
th e a r r a y .
T h e g r id s q u a r e s a r e to p o lo g ic a lly c o d e d b y s e q u e n tia l n u m b e rin g
(le ft to r ig h t , ro w b y row ) w ith in e a c h s h e e t.
A ll d a ta e le m e n ts a r e th e n
a s s ig n e d to a u n iq u e g r id c e ll n u m b e r.
T o a s s ig n d a ta e le m e n ts to g r id c e lls , th e to t a l of a r e a l u n its (in d ic a tin g
p r e s e n t la n d u s e ) w ith in e a c h c e ll i s m a n u a lly m e a s u r e d b y a ty p e o f dot
g r id a c c u r a te to 0 . 01 km2 an d e x p r e s s e d a s th e p e r c e n ta g e o f th e c e ll
c o v e re d b y a p a r t i c u l a r ty p e of a r e a l d a ta .
T h e r e s u lt in g m e a s u r e m e n ts
a r e c o d e d a n d a s s ig n e d to th e g r id s q u a re n u m b e r.
L i n e a r m e a s u r e m e n ts
w ith in e a c h c e l l (m ile a g e s of s h o r e lin e s , r a ilw a y s , a n d s o fo rth ) a r e p e r f o r m e d to a r e s o lu t io n of 1 /1 0 m ile ; th e s e d ata, an d c o u n ts o f n u m b e r s of
p o in t a n d a r e a d a ta e l e m e n ts , a r e s i m i l a r l y a s s ig n e d to g r id c e ll n u m b e r s .
T h u s , a s ig n if ic a n t a m o u n t of d a ta e x tr a c tio n ( m e a s u re m e n t) i s c a r r i e d o u t
o n th e g r a p h ic s to r a g e f ile at th i s s ta g e , a n d it is th e r e s u l t s o f th e s e
m e a s u r e m e n t s th a t a r e s to r e d in th e r e g u l a r m a tr ix o f th e n o n - g r a p h ic
s to r a g e f ile .
N o d e ta ile d c o s t b re a k d o w n s of m a n u a l e f f o r t a r e a v a ila b le ,
b u t i t c a n b e n o te d th a t 1 4 0,000
1-k m 2 g r id c e lls a r e n e e d e d to c o v e r th e
S ta te of New Y o rk , a n d th e m a n u a l p a r t of th e p r o je c t w a s l a r g e en o u g h to
d e m a n d th e f u ll - tim e e f f o r ts of up to 50 w o r k e r s o v e r a p e r io d o f fo u r
y e a r s (1 9 6 7 -7 1 ).
T h e c o d e d n o n - g r a p h ic d a ta a r e k e y p u n c h ed a n d s to r e d on a n IB M 2316 D isk
S to ra g e d e v ic e .3 E a c h in d iv id u a l r e c o r d c o n ta in s a l l th e d a ta f o r f iv e g r id
c e l l s , o r g a n iz e d s e q u e n tia lly in 560 " w o rd s " (th a t i s , 115 w o r d s p e r c e ll).
T h e d a ta a r e c o m p a c te d on th e b a s is of one w o rd (4 b y te s , 32 b in a r y b it s ,
o r 24 f lo a tin g p o in t b i t s , p lu s 8 b it s exponent) p e r s e t of 8 o r 10 r e a l
n u m e r ic in t e g e r s , a n d s to r e d in f ix e d - f o r m a t r e c o r d s ; e m p ty f ie ld s a r e
f ille d w ith z e r o s .
T h e r e c o r d s a r e f ile d f o r d ir e c t a c c e s s , th o u g h th e
r a n d o m iz in g f o r m u la u s e d c r e a t e s 140 in d e x e d s e q u e n tia l g ro u p s o f r e c o r d s ,
e a c h g ro u p c o n ta in in g th e r e c o r d s f r o m one b a s e m a p .
1. I t sh o u ld b e n o te d th a t th e g r id " s q u a r e s " , a r e o n ly a p p r o x im a te ly s q u a r e
a n d t h e i r s h a p e v a r i e s s lig h tly o v e r th e e x te n t of New Y o rk S ta te . T h is i n h e r e n t e r r o r w a s n o t c o n s id e re d to b e s ig n ific a n t in a n y c a lc u la tio n u s in g th e
s u m m a r iz e d g r id c e ll c o n te n ts . 2, H a rd y an d S h elto n 1970. 3 . S h elto n et a l. 1971.
101
T h e r e t r i e v a l p r o g r a m (D A T A L IST1)c a n s e le c t an y in d iv id u a l r e c o r d o r s e t
of re co rd s.
A ny c e ll c a n b e c a lle d 2 b y u s in g th e c o o rd in a te p o in t o f i t s
n o r t h - e a s t c o r n e r ; s im i la r l y , a n y r e c t a n g u la r b lo c k of c e lls ca n b e c a lle d
b y th e c o o rd in a te p o in ts o f b lo c k c o r n e r s .
C e lls ca n a ls o b e c a lle d b y d a ta
it e m s , w h ic h m a y in c lu d e c o u n ty a n d to w n sh ip n a m e s . On r e t r i e v a l , e a c h
in d iv id u a l r e c o r d i s e x p a n d e d in to th e fu ll d a ta s e t f o r th e f iv e s e p a r a t e
g r id c e lls .
U nw anted c e lls o r d a ta v a lu e s a r e s im p ly d is c a r d e d .
T h is i s
th e o n ly f o r m o f r e t r i e v a l p o s s i b le , a n d i t m u s t b e u s e d to g e t e v e n one
v a lu e f r o m o n e g r id c e ll.
T h e r e t r i e v a l of th e to ta l d a ta f r o m one c e ll (o r
s e t of fiv e c e lls ) i s th u s r e l a ti v e ly e ff ic ie n t, b u t th e r e t r i e v a l of o ne v a lu e
f r o m th e e n t ir e file r e q u i r e s p r o c e s s in g of th e e n t ir e f ile .
e x p lic it p o in t e r s in a n y f o r m in c o r p o r a te d in th e f il e .
T h e r e a r e no
U s e r s h a v e c r e a te d
s p e c if ic l i s t s t r u c t u r e s f o r f r e q u e n tly r e q u i r e d r e t r i e v a l s in s e le c te d a r e a s ,
b u t th e s e a r e n o t in c o r p o r a te d o r in d e x e d in th e m a in file .
A ny c o m b in a tio n of d a ta v a lu e s f r o m c e lls c a n b e p ro d u c e d an d a n y m a th e m a tic a l o r lo g ic a l a n a ly s is c a n s u b s e q u e n tly b e m a d e on th e d a ta , a lth o u g h
s p e c if ic a lg o r ith m s m u s t b e p r o g r a m m e d f o r th e d a ta m a n ip u la tio n s
r e q u i r e d in th e s e t a s k s .
U sin g a s e c o n d c o m p u te r p r o g r a m (P L A N M A P 1), a p ic to r ia l r e p r e s e n t a ti o n
of th e g r id s q u a r e s c a n b e p r o d u c e d b y th e c o m p u te r lin e p r in t e r .
In c o n -
ju n c tio n w ith DATA-LIST, th e m a p p in g p r o g r a m P L A N M A P ca n d is p la y a n y
s e le c tio n o r m a th e m a tic a l c o m b in a tio n of g r id v a lu e s .
S y m b o ls c a n b e
o v e r p r in te d to g iv e d iffe re n t g r e y to n e s (ch o ice of fiv e le v e ls ) in e a c h g r id .
N u m e r ic a l v a lu e s (one d ig it) c a n b e p r in t e d in th e m id d le of e a c h g r id so
d is p la y e d .
A g r e a t m a n y l i n e - p r i n t e r m a p s of th e g r id s q u a r e s , sh o w in g
d iffe re n t c o m b in a tio n s of it e m s , c a n b e p ro d u c e d v e r y q u ic k ly (w ith in h o u r s ) .
W h ile th e c o n te n t of th e g r id r e m a in s c o n s ta n t, it i s p o s s ib le to ch a n g e th e
" s c a l e " b y in c r e a s in g th e a r e a of th e li n e - p r i n t e r p a p e r o n w h ich e a c h g r id
i s p ro d u c e d .
No o th e r im a g e m a n ip u la tio n s o r ty p e s of d a ta e x tr a c tio n a r e
p o s s ib le in th i s s y s te m .
T o a s s e s s th i s ty p e of s y s t e m in th e f i r s t c a te g o ry of s to r a g e f o r m a ts , o ne
c o u ld c o m p a r e th e a b ility of th e LU N R s y s t e m to m a n ip u la te i t s n o n - g r a p h ic
s to r a g e w ith th e a b ility to m a n ip u la te th e o rig in a l g r a p h ic a lly s to r e d d a ta
1. S h elto n a n d D im o c k 1971a, 1971b.
s e le c te d f o r r e t r i e v a l .
2. " C a lle d " in th i s c o n te x t m e a n s
102
m a n u a lly .
T h e o r ig i n a l g r a p h ic a lly s to r e d d a ta c o u ld b e a s s u m e d to c o m -
p r i s e a p p ro x im a te ly 140 s h e e t s of p o in t d a ta s im i la r l y r e c o r d e d .
T he effo rt
r e q u i r e d to s u m m a r iz e a n d o v e r la y th e v a rio u s ty p e s of d a ta e le m e n ts f r o m
th e c o n tr a s tin g f o r m a ts c o u ld b e e s tim a te d a n d c o m p a re d .
Such a d ir e c t
c o m p a r is o n w o u ld , h o w e v e r , b e m is le a d in g , an d th e r e in l i e s th e k e y to
a s s e s s i n g th e u ti lit y of L U N R -ty p e s y s te m s .
T h e n o n -g ra p h ic s to r e d o e s
n o t c o n ta in th e s a m e d a ta s e t a s th e g ra p h ic s to r e .
I t c o n ta in s a s e le c te d
s e t of m e a s u r e m e n t s m a n u a lly d e riv e d f r o m th e g ra p h ic s t o r e a t c o n s id e r a b le
e x p e n s e a n d r e c o r d e d in a n a r b i t r a r y f o r m a t.
T h e LUNR s y s t e m c a n o n ly
m a n ip u la te a n d d is p la y th o s e m e a s u r e m e n ts ; i t h a s no a c c e s s to th e s o u r c e
d a ta .
A s m e n tio n e d in th e s y s t e m d e s c r ip tio n a b o v e , th e m a n u a l p r o c e s s of
c r e a tin g n o n -g r a p h ic f o r m a t s of a r b i t r a r y r e g u l a r a r e a s in v o lv e s m e a s u r in g
a n d co d in g a l l p r e s e n t la n d u s e a r e a s , m e a s u r in g an d cod in g lin e le n g th s ,
a n d c o u n tin g a n d co d in g p o in ts .
T h e s e a r e h ig h - o r d e r m a n u a l te c h n iq u e s
(s e e C h a p te r 3, p. 78) th a t e x t r a c t d a ta in h e r e n t in th e f ile s t r u c t u r e of
th e m a p s in v o lv e d , a n d f o r r e a s o n s of c o s t a n d tim e th e y a r e n o t u s u a lly
a p p lie d to m o r e th a n a li m it e d n u m b e r of m a p s h e e ts .
If th e s e m e a s u r e m e n t s a r e g ro u p e d a c c o rd in g to t h e i r o c c u r r e n c e in 1 - k m2
c e l l s , th e o r ig in a l s p a ti a l r e l a ti o n s h i p s of th e d a ta e le m e n ts a r e lo s t an d
a r e r e p l a c e d b y th e a r b i t r a r y r e la tio n s h ip in h e r e n t in th e r e g u l a r a r e a
f o r m a t.
T h is in fo rm a tio n r e d u c tio n in c lu d e s th e l o s s of o r ig in a l a r e a
b o u n d a rie s (b o th t h e i r c o n fig u ra tio n a n d p r e c i s io n of lo c a tio n ) , l o s s o f
p r e c i s io n o f p o in t lo c a tio n , a n d lo s s of lin e s e g m e n t c o n fig u ra tio n an d
p r e c i s io n of lo c a tio n .
U n d e rly in g th e e n t ir e m a n u a l tr a n s f o r m a tio n p r o c e s s
i s th e a s s u m p tio n th a t th e m e a s u r e m e n ts b e in g m a d e w ill b e r e q u i r e d b y
th e u s e r a n d th a t th e l o s s of in fo rm a tio n i s n o t im p o rta n t to th e u s e r .
In
t e r m s of th e u s e of th e s u b s e q u e n t d a ta , th e lo s s of in fo rm a tio n i s , o f
c o u r s e , g r e a t e s t w h en s m a l l n u m b e r s of c e lls a r e c o n s id e r e d , a n d is
m in im iz e d w h en l a r g e n u m b e rs o f th e c e lls a r e c o n s id e re d .
T h e t a s k s e v e n tu a lly a s s ig n e d to th e c o m p u te r to m a n ip u la te th i s n o n - g r a p h ic
s to r a g e a r e r e l a ti v e ly s im p le : th o s e of r e a d in g th e d a ta w r itt e n in th e f il e ,
s e le c tin g a n d g ro u p in g th e m on c o m m a n d , an d p ro d u c in g a p ic to r ia l d is p la y
103
of th e r e s u lt .
In th e t e r m s u s e d to d e s c r ib e m a n u a l p r o c e s s e s in C h a p te r 3,
th e y in v o lv e th e te c h n iq u e s of r e a d in g d a ta , g ro u p in g d a ta (m e r g e , d is s o lv e ,
a n d g e n e ra te ) , a n d p e r f o r m in g d a ta m ove an d s c a l e ch a n g e o n o u tp u t.
T h ese
te c h n iq u e s r e q u i r e a s u b s t a n ti a l d e g r e e of m a n u a l e f f o r t, a n d if a la r g e
n u m b e r of c e lls h a v e to b e p r o c e s s e d (a s f o r th e s ta te - w id e d is p la y of
s e le c te d d a ta it e m s ) , th e c o m p u te r - a id e d p r o c e s s e s w o u ld te n d to b e c h e a p e r
a n d quic k e r th a n m a n u a l te c h n iq u e s , e v e n tho u g h in e ffic ie n t in t e r m s of
c o m p u te r u s a g e .
T h e te c h n iq u e s of r e a d in g d a ta , g ro u p in g d a ta , a n d s c a l e ch a n g e r e f e r r e d
to a b o v e , alth o u g h h ig h in m a n u a l m o to r e f f o r t, a r e n e v e r t h e le s s s t i l l in
th e lo w - o r d e r g ro u p (s e e C h a p te r 3, pp. 78-79) g e n e ra lly c o n s id e r e d to b e
e c o n o m ic a lly p r a c t i c a l a s w o rk in g to o ls f o r a li m it e d n u m b e r o f m a p s (su ch
a s m ig h t b e r e q u i r e d b y a lo c a l p la n n in g a g e n c y ).
T h e s y s t e m d e s ig n e r s
s e e m to h a v e c o n s c io u s ly o r s u b c o n s c io u s ly r e c o g n iz e d th i s f a c t a n d th e f il e
s t r u c t u r e of LU N R i s a t i t s m o s t e f fic ie n t in r e t r i e v i n g d a ta f r o m s m a ll
a re a s.
T h e c o n s tr a in t o n th e s y s t e m , h o w e v e r, is th e low r e s o lu tio n
in h e r e n t in th e n o n - g ra p h ic d a ta f o r m a t, w h ic h s e r io u s ly li m i t s th e u tility
of th e s y s t e m f o r a n a ly s is of s u c h li m it e d a r e a s .
D a ta a r e a d d e d to th e n o n - g ra p h ic s t o r e in th e s a m e m a n n e r a s th e o r ig in a l
d a ta .
W ith s m a l l a m o u n ts of d a ta th i s i s a n e a s y p r o c e s s , now th a t th e f il e s
a r e e s ta b lis h e d .
W ith l a r g e r a m o u n ts of d a ta , s u c h a s a new p r e s e n t la n d
u s e s u r v e y , m a n u a l d a ta e x t r a c ti o n to c r e a te th e n o n - g r a p h ic f ile w o u ld
d e m a n d a s m u c h e f f o r t a s f o r th e o r ig in a l d a ta s e t .
O th e r th a n th e a b ility
to m a n ip u la te d a ta a s d e s c r ib e d ab o v e , th e m a in o v e r a l l b e n e fit o f th e LU N R
a p p ro a c h i s p e rh a p s th e s ta te - w id e c l a s s i f ic a t io n s of d a ta now a v a ila b le
in b o th g ra p h ic a n d n o n - g ra p h ic f o r m s w h ich h a v e r e s u lt e d f r o m th e d a ta
g a th e r in g a c tiv ity u n d e rly in g th e c r e a tio n of th e a c tu a l s y s t e m it s e lf .
A r b i t r a r y R e g u l a r - A r e a S y s te m s - T y p e 2
T h e s e c o n d ty p e o f s y s t e m in th e c a te g o r y of s to r a g e f o r m a t u s in g a r b i t r a r y
r e g u l a r a r e a s i s c h a r a c te r iz e d b y m a n ip u la tiv e fu n c tio n s r e ly in g o n a s m a l l
c e ll s iz e r e l a ti v e to th e s o u r c e d a ta e le m e n ts b e in g s to r e d .
T h is ty p e u s e s
s in g le d a ta s e t s , o r f a c t o r s d e r iv e d b y a c o m b in a tio n o f s u c h d a ta s e ts ,
p la c e d in s m a l l a r b i t r a r y g r id c e lls w h ich c a n th e n b e s p a tia lly m a n ip u la te d
104
b y th e c o m p u te r.
S uch m a n ip u la tio n i s b o th f a c i li ta te d and c o n s tr a in e d b y
th e s m a l l g r id f o r m a t, a n d b y th e r e q u i r e m e n t f o r a n en d p ro d u c t w ith one
d a ta v a lu e p e r g r id c e ll.
T h e r e s u l t s a r e u s u a lly d is p la y e d a s li n e - p r in t e r
c h a r a c te r m a p s.
SYM AP V1 i s th e b e s t know n an d m o s t w id e ly u s e d p r o g r a m o f th i s ty p e .
O th e r s i m i l a r p r o g r a m s in c lu d e MIADS2 a n d MIADS23 (U. S. F o r e s t S e rv ic e ),
GRID4 ( H a rv a r d U n iv e rs ity ) , L IN M A P 5 a n d C O L M A P 6 ( M in is tr y o f H o u sin g
a n d L o c a l G o v e rn m e n t, U .K .) , MANS7 ( U n iv e rs ity of M a ry la n d ), GEOM AP8
(U n iv e r s ity of W a te rlo o ), M AP019 (New Y o rk S ta te , D e p a rtm e n t of P u b lic
W o rk s ), B R A D M A P 10 (B ra d fo rd , U .K .) , a n d n u m e ro u s o th e r u n n am ed ,
u n d o c u m e n te d e x a m p le s th a t e x h ib it th e c h a r a c t e r i s t i c s of th e c a te g o r y a n d
a r e in lo c a l u s e , f o r e x a m p le th e s y s t e m d e v e lo p e d a n d u s e d in th e G eo g rap h y
D e p a rtm e n t, U n iv e rs ity of M ich ig an , A nn A r b o r , U. S. A.
C o n c e p tu a lly , th e tr a n s f o r m a tio n f r o m s o u r c e d a ta f o r m a t to n o n -g ra p h ic
f o r m a t in v o lv e s o v e rla y in g th e s o u r c e d a ta w ith a n a r b i t r a r y r e c ta n g u la r
g r id .
T h e g r id c e lls c a n b e of a n y s iz e , b u t th e y u s u a lly a p p ro x im a te to th e
a r e a on th e s o u r c e m a p c o v e re d b y one s y m b o l o n th e lin e p r i n t e r a v a ila b le .
T h e o n ly c h o ic e th a t c a n a ffe c t th e r e s o lu t io n of th e n o n - g r a p h ic s to r e is
e x e r c is e d a t th i s s ta g e , an d s u b s e q u e n t c h a n g e s of s c a l e o n ly a ffe c t th e a r e a
o f p a p e r u s e d to d is p la y th e r e c o r d e d d a ta s e t.
T h e s o u r c e d a ta a r e th e n
éo d e d in th e new g r a p h ic f o r m a t of th e a r b i t r a r y g r id , th e c o n s tr a in t b ein g
th a t o n ly o n e v a lu e c a n b e a llo c a te d to e a c h g r id c e ll.
P o in ts a r e a s s ig n e d
o n e c e l l e a c h , li n e s a r e r e p r e s e n t e d a s s tr in g s of a d ja c e n t c e lls , and a r e a s
a r e d e s c r ib e d a s c l u s t e r s of c e lls .
F u r t h e r m a n u a l tr a n s f o r m a tio n to n o n -
g ra p h ic f o r m a t in v o lv e s o n ly th e a s s ig n m e n t of a s im p le c o o rd in a te s y s te m
to th e g r id s t r u c t u r e a n d th e r e a d in g of th e c e ll v a lu e f o r th e a p p r o p r ia te
c e ll c o o rd in a te .
T h e r e s u lt in g d a ta s e t i s th u s m e tr ic a lly an d to p o lo g ic a lly
c o d e d , w ith th e r e l a ti o n s h i p s in h e r e n t in th e a r r a y .
T he a r r a y m ay o r m ay
not b e r e l a t e d to r e a l - w o r l d lo c a tio n , th a t i s , i t m a y o r m a y n o t h av e r e a l w o rld d im e n s io n s w h ich a r e know n to th e s y s te m .
M a n ip u la tiv e c h a r a c t e r i s -
t i c s of th e s y s t e m a r e u s u a lly in d e p e n d e n t of d im e n s io n s e x t e r n a l to th e a r r a y .
1. S y n a g ra p h ic C o m p u te r G ra p h ic s , L a b o r a to r y f o r C o m p u te r G ra p h ic s and
S p a tia l A n a ly s is , H a r v a r d U n iv e r s ity , U .S .A . SYM AP w a s o r ig in a lly d e v e lo p e d b y H. T . F i s h e r an d B e tty B e n s o n , a n d s u b s e q u e n t m o d ific a tio n s to th e
p r o g r a m h a v e b e e n m a d e b y A . S c h m id t, R . R u s s e ll, D. S h e p a rd , M. M anes and
K . R e in e . (See H a r v a r d U n iv e r s ity 1968).
2. A m id o n 1964. 3. A m id o n 1966.
4 . S in to n a n d S te in itz 1969. 5. G a its 1968. 6. P e a r s o n 1972. 7. P f a lt z 1967c.
8. S te in e r 1970. 9. New Y o rk S ta te 1967. 10. T o m lin s o n , K. R. an d Huff 1972.
105
In p r a c t i c e , 1 a c o o rd in a te s y s te m of a r b i t r a r y p la n e g r id s is s u p e r im p o s e d
o n th e s o u r c e m a p an d th e n u m e r ic a l c o d e s of p o in ts , li n e s , o r a r e a s a r e
r e c o r d e d m a n u a lly o r b y u s e of a m e c h a n ic a l c o o rd in a te r e a d e r .
In so m e
s y s t e m s , a r e a s ( c l u s t e r s of g r id c e lls ) ca n b e c o d e d b y r e c o r d i n g o n ly th e ir
le f t- h a n d e d g e (a s s u m in g th e m a p i s e n tir e ly c h o ro p le th ic ), o r b y r e c o r d in g
p o in ts w h ic h r e p r e s e n t v e r t ic e s of s tr a i g h t- s id e d p o ly g o n a l a r e a s .
p r o c e s s i s slow a n d a t b e s t s e m i- a u to m a tic .
The
T h e c o n v e rs io n o f a b a s e m a p
of M o n tre a l2 (12 m ile s x 18 m i le s , 1 :2 5 ,0 0 0 s c a l e , 500 c e n s u s t r a c t s ) to a
n o n - g r a p h ic , s m a l l - g r i d f o r m a t to o k 22 m a n -d a y s .
S im ila r ly , th e n o n -
g r a p h ic c o d in g of c ity b lo c k s d e riv e d f r o m 1 :5 0 ,0 0 0 b a s e m a p s f o r P a r i s 3
to o k 12 m a n -m o n th s .
S e v e r a l ty p e s o f im a g e m a n ip u la tio n an d d a ta e x tr a c tio n c a n b e c a r r i e d o ut
o n th e r e s u lt in g n o n -g ra p h ic d ata.
T h e im p lic it a s s u m p tio n in th e m a jo r ity
of s u c h m a n ip u la tio n s i s th a t th e s m a ll g r id c e ll s iz e a n d s in g le v a lu e p e r
c e ll allo w th e c e lls to b e r e g a r d e d a s an a r r a y of p o in ts w ith o u t s ig n if ic a n t
l o s s of in fo r m a tio n .
T h is a s s u m p tio n i s a c c e p ta b le o n ly if th e c e ll s iz e
it s e l f i s s m a l l in r e l a ti o n to th e r e a l - w o r l d d a ta e le m e n ts .
T h e b o u n d a ry
o f th e a r e a a ro u n d th e p o in t (the lin e s e g m e n ts fo r m in g th e ce ll) a r e im p lic it,
n o t e x p lic it, w ith in th e s y s te m .
T h e e x a m p le th a t w ill b e u s e d to il l u s t r a t e
th e p r a c t i c a l p ro b le m s of T y p e 2 of th e c a te g o r y of s to r a g e f o r m a t u s in g
a r b i t r a r y r e g u l a r a r e a s is th e w e ll-d e v e lo p e d a n d w id e ly a p p lie d SYMAP
s y s te m .
SYM A P S y s te m - E x a m p le of T ype 2 of th e A r b i t r a r y R e g u la r - A r e a C a te g o ry
In SYM A P V,1 t h r e e f ix e d - fo r m a t s e q u e n tia l f il e s a r e e s ta b lis h e d f o r e a c h
s o u rce m ap.
T h e f i r s t f ile c o n ta in s th e c o o r d in a te s of th e c e lls th a t f o r m th e
o u te r b o u n d a ry of th e m a p p e d a r e a , th e s e c o n d c o n ta in s th e c o o r d in a te s of
th e c e lls th a t f o r m in t e r n a l b o u n d a rie s w ith in th e m a p p e d a r e a , a n d th e t h i r d
c o n ta in s th e c o o r d in a te s of c e lls th a t h a v e d a ta v a lu e s a s s o c ia te d w ith th e m .
T h e r e a r e no e x p lic it p o in te r s in th e f il e s .
G iven th e s e th r e e f i l e s , th e
fo llo w in g ty p e s of b a s ic m a n ip u la tio n s ca n b e c a r r i e d out.
V alu e s p ro v id e d
a t s in g le g r id c o o rd in a te p o in ts c a n b e s p r e a d h o m o g e n e o u s ly o v e r a r e a s
( c l u s t e r s of g r id c e lls ) p re v io u s ly d e s c r ib e d to th e s y s t e m b y th e o u te r an d
in n e r b o u n d a ry f il e s .
T h is p r o c e s s is a k in to m a n u a l m a p c o lo u rin g .
How -
e v e r , if th e v a lu e s to b e " c o lo u re d " a r e c h o s e n s o th a t u n w an te d v a lu e s
1. S c h m id t, A . 1966.
2. S eem an 1973.
3. A te l ie r P a r i s i e n d 'U r b a n is m e 1972.
106
r e m a in
b la n k , th e n th e p r o c e s s i s e q u iv a le n t to th e m a n u a l d a ta e x tr a c tio n
p r o c e d u r e of r e a d in g , id e n tify in g , a n d r e t r ie v in g s p e c ific d a ta e le m e n ts o r
d a ta p a t te r n s .
F o r up to 1 ,0 0 0 p o in ts w ith d a ta v a lu e s a tta c h e d , is o lin e s c a n b e c a lc u la te d
a t e q u a l in t e r v a l s o v e r th e ra n g e of v a lu e s of p o in t d a ta p ro v id e d .
T h e e q u i-
v a le n t m a n u a l im a g e m a n ip u la tio n p r o c e s s , c o n to u rin g , i s e x tr e m e ly
e ffic ie n t in t e r m s of c a lc u la tin g th e p o s itio n of th e is o lin e s , a s it in v o lv e s a
h ig h d e g r e e of m e n ta l im a g e p r o c e s s in g ; h o w e v e r, p lo ttin g th e r e s u lt in g lin e s
is a r e l a ti v e ly slow m o to r p r o c e s s .
C o m p a ra b le co n to u rin g o f 500 p o in ts on
a 2 0 -in . x 3 0 -in . m a p , f o r e x a m p le , co u ld b e m a n u a lly a c c o m p lis h e d in 3 o r
4 m a n -h o u rs.
A t h i r d ty p e of m a n ip u la tio n i s lo c a tio n of th e b o u n d a rie s o f s p a ti a l u n its ,
e x t r a c te d f r o m p o in t in f o rm a tio n b y n e a re s t- n e ig h b o u r m e th o d s .
T h is is
e s s e n ti a ll y a c a lc u la te - a n d - c o m p a r e p r o c e s s c a r r i e d out o n th e p o in ts in th e
d a ta v a lu e f il e .
T h e r e s u l t s a r e c a lc u la te d f o r e a c h row o f th e a r r a y a n d a r e
p r in t e d s e q u e n tia lly .
T h e m a n u a l e q u iv a le n t i s r a t h e r ak in to a r e v e r s e f o r m
of c e n tr o id a llo c a tio n , w h e r e th e p o in ts a r e know n b u t th e b o u n d a r ie s b e tw e e n
th e m h a v e to b e d e te rm in e d .
If m a n u a l e s tim a tio n is u s e d , th e m e n ta l
s e le c tio n p r o c e s s i s q u ic k , b u t th e m o to r p r o c e s s of p lo ttin g th e li n e s ta k e s
tim e .
F u r t h e r m o r e , th e e r r o r le v e l in th e e s tim a tio n p r o c e s s i s d iffic u lt
to d e te c t.
If a m o re q u a n tita tiv e m a n u a l p r o c e s s i s a tte m p te d , s u c h a s
m e a s u r e m e n t b e tw e e n c e n tr o id s to d e te r m in e m id - p o s itio n s , th e n e x te n s iv e
m a n u a l m e a s u r e m e n t i s in v o lv e d a n d th e r e s u l t s t i l l in c o r p o r a te s v a lu e
ju d g e m e n ts .
Y et a t h i r d m a n u a l a p p ro a c h to th e s a m e ta s k c o u ld b e to
e m u la te th e c o m p u te r p r o c e s s an d la y a fin e g r id o v e r th e p o in ts c o n c e rn e d .
T h e g r id c e lls a ro u n d e a c h p o in t co u ld b e c o lo u re d s te p b y s te p u n til
b o u n d a ry c o n d itio n s w e r e d e te r m in e d . F o r an y m a n u a l a p p ro a c h to s u c h
p r o x im a l im a g e m a n ip u la tio n , th e ti m e to h a n d le 100 p o in ts on a 2 0 - in x 3 0 -in .
s h e e t w o u ld b e in e x c e s s of 3 m a n -h o u r s .
In c o n t r a s t, th e c o m p u te r c a n m a n ip u la te an e q u iv a le n t n o n - g r a p h ic s t o r e
an d p ro d u c e a l l t h r e e ty p e s of d a ta m a n ip u la tio n f o r a 20 -in . x 3 0 -in . m a p
in a p p r o x im a te ly 50 s e c 1 of IB M 3 7 0 /1 5 5 c e n tr a l p r o c e s s in g u n it (cpu) tim e .
T y p ic a l a c tu a l e x a m p le s a r e r e t r i e v i n g a n d d is p la y in g a l l c ity b lo c k s in P a r i s 2
1. S ee S c h m id t, A . 1972a f o r s i m i l a r e x a m p le .
d 'U r b a n is m e 1972.
2. A te lie r P a r i s i e n
107
w hich c o s ts b e tw e e n $12 o r $ 7 5 , d ep e n d in g on th e ty p e of m a n ip u la tio n
(c o n fo rm a i, c o n to u r, o r p ro x im a l).
m a p of C a n a d a
T h e g e n e ra tio n of a SYM AP l i n e - p r i n t e r
s h o w in g 258 c e n s u s s u b d iv is io n s , c o n fo rm a lly s h a d e d , c o s ts
a p p ro x im a te ly $2 0 .
T h e p ro d u c tio n of a s i m i l a r m a p f o r M o n tre a l,2 sh o w in g
500 c e n s u s t r a c t s , c o s ts b e tw e e n $2 an d $10.
S im ila r p r o c e s s in g c a p a b ili tie s h av e b e e n d ev e lo p ed in o th e r s y s t e m s of
th e SYM AP ty p e .
A p r o g r a m c a lle d SECTIO N c r e a te d a t th e U n iv e r s ity of
I ll in o is 3 p r o d u c e s a c r o s s - s e c t i o n p r o f ile a lo n g a ro w o r a c o lu m n o f a
SYM A P d a ta b a s e a t th e c o s t of a p p r o x im a te ly 20 s e c of IB M 3 7 0 /1 5 5 cp u
ti m e .
A p ro g ra m
n a m e d V IEW IT p r o d u c e d b y th e U . S. F o r e s t S e rv ic e 4
o p e r a t e s on a M IADS d a ta b a s e a n d c a lc u la te s an d d is p la y s th e a r e a s v is ib le
w ith in a g iv e n r a d i u s f r o m a g iv e n c e ll, b a s e d on e le v a tio n v a lu e s a s s ig n e d
to th e o th e r c e lls .
F o r a n a r r a y of a p p ro x im a te ly 52 x 52 c e lls , th i s
p r o c e s s c o s ts 1 s e c of UNIVAC 1108 cpu ti m e .
T h e s e s im p le ty p e s of m a n ip u la tio n , w h ich in v o lv e b o th im a g e m a n ip u la tio n
a n d d a ta e x tr a c tio n f r o m th e n o n -g ra p h ic d a ta s to r a g e , a r e th u s e f f ic ie n t
an d in e x p e n s iv e .
T h e y r e l y on th e fa c t th a t th e n o n -g ra p h ic d a ta b a s e i s
s t r u c t u r e d a s an a r r a y , th a t th e d a ta c a n b e h a n d le d a s p o in t v a lu e s in a n
a r r a y , an d th a t e x is tin g d ig ita l c o m p u te r s a r e p a r t i c u l a r l y a d e p t a t a r r a y
m a n ip u la tio n .
C o m p a re d w ith m a n u a l te c h n iq u e s , th e c o m p u te r s h a v e
a d v a n ta g e s in t h e i r s p e e d o f c a lc u la tio n w h en an y m o re th a n a few p o in ts
a r e in v o lv e d , an d in t h e i r a b ility to p lo t th e r e s u l t s of t h e i r c a lc u la tio n s
q u ic k ly on a lin e p r i n t e r (up t o 2 ,0 0 0 lin e s of c h a r a c te r s p e r m in ).
Som e S Y M A P -type s y s t e m s p ro v id e a v e r y s im p le v e r s io n o f a n o v e r la y
p r o c e s s b y t h e i r a b ility to co m b in e d a ta v a lu e s f o r one g r id c e ll f r o m
d if fe re n t d a ta s e t s (u n d e r th e c o n tro l of a s e t of ru le s ) a n d to a r r i v e a t a
new s in g le v a lu e w h ic h i s th e n r e c o r d e d f o r th e c e ll.
T h e u s e of SYM A P in c o n ju n c tio n w ith a p r o g r a m n a m e d SYMVU
a n o b liq u e -v ie w m a p f r o m th e s in g le d a ta b a s e .
p ro d u c e s
T h e m a p s a r e d ra w n b y
a u to m a tic p lo ttin g m a c h in e s th a t u s e th e o u tp u t f r o m th e c o m p u te r.
B ased
on in te rp o la tio n , th e s e d ra w in g s show s p a tia l v a r ia tio n s in v a lu e s o f th e
d a ta b y v a r ia tio n s in th e h e ig h t of a s u r f a c e r e p r e s e n t e d a s i f s e e n o b liq u e ly
1. P o d e h l, 1973.
2. S e e m a n 1973. 3. D udnik 1972. 4. A m idon 1972.
H a r v a r d U n iv e r s ity 1968. 6. SYMVU is b a s e d on a p r o g r a m o r ig in a lly d e v e lo p e d b y F r a n k R e n s . S u b se q u en t m o d ific a tio n s h av e b e e n p ro v id e d b y
K a th le e n R e in e , L a n n o n L e im a n a n d o th e r m e m b e rs of th e L a b o r a to r y f o r
C o m p u te r G ra p h ic s an d S p a tia l A n a ly s is (S ch m id t, A. 1972b).
5.
108
fro m above.
T h e in te r p o la te d fa c ts a r e sh o w n w ith o u t n e e d f o r c la s s in g .1
A f u r t h e r d e v e lo p m e n t of th is c a p a b ility f o r p ic to r ia l d is p la y i s a p r o g r a m
n a m e d O B L IX , b y w h ich c o n to u r lin e s a r e p r e s e n t e d on th e p e r s p e c tiv e view
of th e 3 - d im e n s io n a l s u r f a c e .
T h is l a t t e r c a p a b ility , h o w e v e r, i s o n ly a t th e
s ta g e of a c tiv e d e v e lo p m e n t.2
SYM AP V3 h a s a w id e n u m b e r of s t a t i s t i c a l s u p p o r t o p tio n s lin k e d to th e
m a p p in g s y s t e m , w h ich p e r m it c a lc u la tio n of s u c h a n a ly s e s a s m e a n s ,
s ta n d a r d d e v ia tio n s , h is to g r a m s , a n d p e r c e n til e g ro u p s o f th e d a ta .
T h e e a r l i e r v e r s io n s of SYM AP u s e d l a r g e r - s c a l e c o m p u te r s (fo r e x a m p le ,
IB M 7094), b u t th e c u r r e n t s y s t e m c a n u s e m e d iu m - s c a le c o m p u te r s (su ch
a s th e IB M 3 6 0 /4 0 a n d lim ite d v e r s io n s c a n r u n on s m a l l e r m a c h in e s .
T h e c h a r a c t e r i s t i c s of S Y M A P -type s y s te m s in th i s c a te g o r y a r e : r e l a ti v e ly
la b o r io u s p r e p a r a t i o n of th e b a s i c g r id d a ta ; r e l a ti v e ly c o a r s e d a ta r e p r e s e n ta tio n (u s e o f l a r g e r s c a l e s to a c h ie v e b e t t e r r e s o lu t io n m u ltip lie s th e m a n u a l
p r e p a r a tio n n e c e s s a r y ) ; s tr a ig h tf o r w a r d c o m p u ta tio n a l o p e r a tio n s ; s im p le
b u t u s e f u l d a ta m a n ip u la tio n c a p a b ilitie s on th e v e r y s im p le (one v a lu e p e r
c e ll) d a t a s e t s th a t th e y a r e a b le to h a n d le ; in a b ility to h a n d le c o m p le x d a ta
s e t s ; a n d a s im p le g ra p h ic c a p a b ility f o r d is p la y .
T h e la b o u r c o n s tr a in t
o n in p u t u s u a ll y li m i t s th e a r e a h a n d le d b y th e s y s te m .
h a n d le d in p u n c h - c a r d f o r m . S to ra g e i s n o t c o m p a c t.
T h e d a ta a r e u s u a lly
T h e ti m e r e q u i r e d to
re s p o n d to r e q u e s t s f o r m a n ip u la tio n a n d d is p la y of s e le c te d d a ta s e t s i s
w ith in a d a ily ti m e f r a m e , p ro v id e d th e b a s e m a p i s a l r e a d y co d e d .
ta tio n t i m e s a r e lo w .
C om pu-
C o s t of d a ta p r e p a r a tio n i s fr e q u e n tly f o u r o r f iv e ,
a n d s o m e tim e s m a n y m o r e , t i m e s h ig h e r th a n s u b s e q u e n t c o m p u ta tio n a l
c o s t of m a n ip u la tio n a n d d is p la y of th e s a m e d a ta s e t.
T h e s y s t e m s th a t b e lo n g to T y p e 2 o f th i s c a te g o r y a r e u s e f u l f o r g e o g r a p h ic a l
t a s k s th a t in v o lv e few b a s e m a p s h e e ts a n d s im p le d a ta s e ts ; th e m a n ip u la tio n
a n d d is p la y of c e n s u s d a ta f o r u r b a n a r e a s i s a ty p ic a l a p p lic a tio n .
S im ila r ly ,
s m a l l - s c a l e d is p la y of w id e r d a ta d is tr ib u tio n s ca n b e e f fe c tiv e ly h a n d le d .
T h e s y s t e m s a r e n o t e ffic ie n t f o r s to r a g e an d m a n ip u la tio n o f e x te n s iv e m a p
s e r i e s , a n d h a n d lin g of lin e an d n e tw o rk d a ta a n d flow m a n ip u la tio n s i s
d iffic u lt.
T h e s y m b o lic r e p r e s e n t a ti o n d o e s n o t allow th e h a n d lin g o f c o m -
p lic a te d d e s c r i p tio n s , s u c h a s a f o r e s t s o il c a p a b ility w ith m u ltip le
1. F i s h e r 1970.
1968.
2. S ch m id t, A. 1970, T h o m a s , A. 1972.
3 . H a r v a r d U n iv e r s ity
109
s u b f a c to rs .
E v e n in s itu a tio n s w h e r e th e c a p a b ilitie s o f th e s y s t e m s ca n b e
p u t to t h e i r b e s t u s e , a p p lic a tio n of th e d is p la y s in a r e s e a r c h o r d e c is io n m a k in g c o n te x t is lim ite d .
In a n a c a d e m ic s e n s e , th e te c h n iq u e s a r e v a lu a b le
f o r r a i s i n g q u e s tio n s a b o u t d is tr ib u tio n s , b u t a r e p o o r f o r p ro v id in g , d a ta in a
f o r m on w h ich d e c is io n s ca n b e b a s e d .
P o s s ib l y one of th e m o s t la s tin g
b e n e fits of th e s e s y s t e m s i s t h e i r fu n c tio n of tr a in in g t h e ir u s e r s in e l e m e n t a r y te c h n iq u e s of n o n - g r a p h ic s p a ti a l d a ta h a n d lin g ; a n o th e r i s in p ro v id in g
low - c o s t e x a m p le s of c o m p u te r- m a n ip u la te d g e o g ra p h ic a l d a ta a s a n e x c e lle n t
v is u a l a id , w h ich s e r v e s to in tro d u c e th e p o s s i b ili tie s of f u r th e r u s e of
s u c h c a p a b ilitie s in p la n n in g o r a d m in is tr a tiv e e n v iro n m e n ts.
P O IN T DATA CA TEG O R Y O F SYSTEM S
T h e s e c o n d lo g ic a l c a te g o r y of s to r a g e f o r m a ts o u tlin e d in F ig . 4 . 7 is th a t
o f p o in t d ata.
" P o in t d a ta s y s t e m s " h a n d le r e a l - w o r l d d a ta e le m e n ts s to r e d in th e f o r m
of i r r e g u l a r l y d is tr i b u te d p o in ts .
T h e in h e r e n t lim ita tio n s o f th e ty p e s of
o p e r a tio n th a t c a n b e p e r f o r m e d on th e s u b s e q u e n t s t o r e o f in fo r m a tio n w e r e
d is c u s s e d e a r l i e r in th i s c h a p te r (p ag e 9 6 ).
N e v e r th e le s s , th e r e l a ti v e
s im p l ic i ty o f s to r in g a n d p r o c e s s in g p o in t d a ta h a s le d to u s e o f th e f o r m a t
asx th e b a s i s f o r a n u m b e r of c u r r e n t s y s t e m s , in c lu d in g : F R IS 1 (S w edish
B o a rd f o r R e a l E s ta te D a ta ); GIST2 (G e o g ra p h ic In fo rm a tio n S y ste m , New
Y o rk ); C o v e n try 3 (T h e P o in t D ata S y s te m , C o v e n try , U .K .) ; N C C 4 (The
N a tio n a l C a p ita l C o m m is s io n S y ste m , O tta w a , C an a d a); GRDSR5 ( S ta tis tic s
C an a d a); a n d th e p r o p o s e d G ISP 6 (G e o g ra p h ic In fo rm a tio n S y s te m f o r P la n n in g ,
U .K .) .
A s show n on F ig . 4. 7, th e u s e of th e s im p le p o in t f o r m a t o f s to r a g e is o p tim u m f o r r e a l - w o r l d p o in t d a ta b u t im p lie s d a ta r e d u c tio n w h en u s e d to
r e p r e s e n t a r e a s (in c lu d in g c l u s t e r s of p o in ts) a n d li n e s .
T o a g r e a t e x te n t,
c u r r e n t s y s t e m s in th i s c a te g o r y a c c e p t th e d a ta r e d u c tio n an d u s e p o in t
d a ta s y s t e m s to m a n ip u la te a r e a c e n tr o id s a s s u r r o g a te s f o r d a ta s e ts
g ro u p e d b y i r r e g u l a r a r e a s .
T h is is p a r t l y b e c a u s e r e l a ti v e ly few o f th e
ty p e s of r e a l - w o r l d d a ta e le m e n ts th a t a r e of i n t e r e s t to in v e s tig a to r s a r e
t r u l y p o in t p h e n o m e n a , a n d p a r t ly due to th e c o m p le x ity an d e x p e n se in h e r e n t
in h ig h e r - o r d e r s y s t e m s th a t c a n h a n d le li n e s an d , p a r t ic u l a r ly , i r r e g u l a r
l .A l f r e d s s o n e t a l. 1970, M e la n d e r e t a l. 1971, S e la n d e r 1970, O ls s o n an d
S e la n d e r 1971, O ls s o n 1971. 2. A m s te r d a m 1968, 1969. 3. C o v e n try C ity
C o u n c il 1970. 4. S y m o n s 1972a. 5. S ta t is tic s C a n a d a 1972a, 1972b. 6. J o i n t
L o c a l A u th o rity 1972.
110
are a s.
It r e m a in s to b e s e e n w h e th e r th e s y s t e m u s e r s ca n a c c e p t th e i n f o r -
m a tio n r e d u c tio n in h e r e n t in th e p o in t s to r a g e of h ig h e r - o r d e r d a ta f o r m a ts .
T h e s im p l ic i ty o f p o in t f o r m a t p r o c e s s i n g h a s le d to i t s e a r l y ad o p tio n b y
a g e n c ie s w is h in g to e s ta b lis h s o m e f o r m of lo c a tio n id e n tif ie r f o r la r g e d a ta
s e t s ( fo r e x a m p le , 20 m illio n r e c o r d s , 120 d a ta v a lu e s p e r r e c o r d 1).
The
r e s u l t h a s b e e n th e d e v e lo p m e n t of r e l a ti v e ly s o p h is tic a te d p r o c e d u r e s to a id
th e p r o c e s s of a llo c a tin g v a r i o u s l y co d e d d a ta to th e a p p ro p r ia te p o in ts .
Even
th o u g h th e i n i tia l s ta g e of c r e a tin g th e n o n -g ra p h ic d a ta file u s u a lly r e l i e s o n
m a n u a l o r s e m i - a u to m a tic te c h n iq u e s , th e m o s t s ig n ific a n t c o n tr ib u tio n of
th e c u r r e n t s y s t e m s l i e s in th e s u b se q u e n t f ile c r e a tio n p r o c e s s e s .
They
h a v e , in f a c t , m a d e it p o s s ib le f o r lo c a tio n id e n tif i e r s to b e a s s ig n e d to d a ta
s e t s th a t c o u ld n o t, f o r a l l p r a c t i c a l p u r p o s e s , h av e b e e n d is p la y e d in c a r t o g r a p h ic f o r m b y c o n v e n tio n a l m a n u a l te c h n iq u e s (due to r e a s o n s o f tim e ,
h u m a n r e s o u r c e s , a n d e x p e n s e , r a t h e r th a n to te c h n ic a l c a p a b ility ).
T h e re is ,
a s c a n b e u n d e r s to o d , s o m e d iffic u lty in c o m p a rin g th e c o m p u te r - a id e d
te c h n iq u e s w ith m a n u a l-a id e d te c h n iq u e s w ith o u t a s s u m in g a g r a p h ic d a ta b a s e
th a t c o u ld n o t b e c r e a te d e c o n o m ic a lly b y m a n u a l m e th o d s , th o u g h s o m e
c o m p a r is o n s w ill b e a tte m p te d l a t e r in th i s d is c u s s io n .
S y s te m s u s in g th e p o in t d a ta a p p r o a c h c o m m o n ly u s e a tr a c in g - ty p e d ig itiz e r
to p ro v id e a c o d e d m e tr ic r e p r e s e n t a ti o n of e x is tin g c a d a s t r a l m a p s .
The
te c h n iq u e s u s e d in v o lv e th e i n i tia l c r e a tio n of a s e t of c o o rd in a te p o in ts th a t
c a n b e u s e d a s in d e x p o in ts f o r th e d a ta s e t s o r d is c r e te d a ta .
A m e d iu m -
to l a r g e - s c a l e c o m p u te r i s m o s t o fte n u s e d to s t o r e an d m a n ip u la te th e d a ta .
V a r io u s a p p ro a c h e s c a n th e n b e u s e d to r e l a t e d a ta to th e c o o rd in a te p o in ts .
R e t r ie v a l of d a ta i s
u s u a lly b y a r b i t r a r y poly g o n o r n e tw o rk , an d d is p la y o f
d a ta i s u s u a lly a c c o m p lis h e d on a lin e p r i n t e r .
B e c a u s e of th e l a r g e q u a n titie s
of d a ta m a n ip u la te d in s o m e s y s t e m s , e f fic ie n t f il e s tr u c t u r e s h a v e b e e n
d e v e lo p e d f o r th e s e le c tio n a n d r e t r i e v a l of s p a tia l d a ta f r o m l a r g e f il e s .
T h e ti m e f o r r e s p o n s e to r e q u e s t s ca n b e r a p id enough to h a n d le d a y - to - d a y
q u e r i e s in v o lv in g d a ta s u m m a r y b y a r e a .
a m e n a b le to a s ta n d a r d iz e d q u e r y f o r m a t.
R e q u e s ts r e p e a te d f r e q u e n tly a r e
T h e s e g e n e ra l s y s t e m c h a r a c t e r i s -
t i c s h a v e le d to th e a d o p tio n of p o in t s to r a g e s y s te m s f o r h a n d lin g q u ite c o m p le x a n d c lo s e ly s p a c e d d a ta s e t s f r o m r e l a ti v e ly s m a ll a r e a s .
1. S ta t is tic s C a n a d a 1972a, 1972b.
They a re
111
c o m m o n ly d e v e lo p e d to h a n d le u r b a n d a ta an d c a n b e u s e d in s m a l l- s c a l e
r e p r e s e n t a ti o n s of r u r a l d ata.
O ne s y s t e m th a t il l u s t r a t e s th e m a in c h a r a c t e r i s t i c s c u r r e n t in th e c a te g o r y
of s to r a g e f o r m a t u s in g p o in t d a ta is GRDSR, th e g e o g ra p h ic a lly r e f e r e n c e d
d a ta s to r a g e a n d r e t r i e v a l s y s te m of S ta t is tic s C an a d a.1
I t is b r ie f ly
d e s c r i b e d b elo w .
GRDSR S y ste m - E x a m p le of P o in t D a ta C a te g o ry
T h e o v e r a l l o b je c tiv e of GRDSR i s to f a c i li ta te th e r e t r i e v a l of s u b s e ts , of
c e n s u s d a ta b y s m a l l a r e a s .
T h e c e n s u s (C an a d a 1971) c o m p r is e s a p p r o x i-
m a te ly 21 m illio n s m a l l d a ta s e t s (120 d a ta v a lu e s p e r s e t of d a ta ), to p o lo g ic a lly c o d e d (by p o s ta l a d d r e s s , a nd e n u m e ra tio n d i s t r i c t a n d a r e a n u m b e rs)
to a n e x t e r n a l g ra p h ic in d e x .
In u r b a n a r e a s , s t r e e t a d d r e s s e s ca n b e
r e l a t e d to a s t r e e t m a p ; in r u r a l a r e a s , e n u m e ra tio n n u m b e rs c a n b e r e l a te d
to e n u m e ra tio n a r e a m a p s .
B o th s t r e e t m a p s a n d e n u m e r a tio n a r e a m a p s
a r e b a s e d on U T M -c o d e d c a d a s t r a l s h e e ts .
T h e i n i tia l s te p in c o n v e rs io n to n o n - g r a p h ic f o r m a t i s co d in g th e e x te r n a l
g r a p h ic in d e x to p o lo g ic a lly an d m e tr ic a lly .
W ith in u rb a n a r e a s , th e s t r e e t
n e tw o rk i s to p o lo g ic a lly co d e d b y s t r e e t n a m e , n o d e n u m b e r, an d civ ic
a d d r e s s ra n g e of s t r e e t s e g m e n ts , a n d i s m e tr ic a lly co d e d b y n o d e c o o r d in a te s .
T h e c o o r d in a te s of p o in ts to w h ic h d a ta f r o m one c ity b lo c k s id e
(face) w i l l e v e n tu a lly b e a llo c a te d a r e i n t e r n a l ly c a lc u la te d f r o m th e m e tr ic
n o d e c o d e s , a c c o r d in g to a g iv e n s e t of r u l e s .
T h e r e s u lt in g n o n -g ra p h ic
d e fin itio n of th e c ity i s te r m e d a n a r e a m a s t e r f il e (A M F).
T h e r e a f te r ,
th e s t r e e t a d d r e s s e s th a t id e n tify th e d a ta s e t s a r e in te r n a lly s ta n d a r d iz e d
b y a p r o g r a m c a lle d th e p o s ta l a d d r e s s a n a ly s is s y s t e m (PA A S), m a tc h e d
t o th e to p o lo g ic a l c o d e s of th e A M F (th ro u g h th e a d d r e s s c o n v e rs io n file ) ,
an d , if th e m a tc h is s u c c e s s f u l, a r e a s s ig n e d th e r e l a t e d m e tr ic co d e (the
b lo c k fa c e p o in t c o o rd in a te ).
in to th e s e s te p s .
V e r ific a tio n a n d e d itin g p r o c e d u r e s a r e b u ilt
In r u r a l a r e a s , c e n tr o id s of p o p u la tio n d e n s ity a r e
m a n u a lly a s s ig n e d to e a c h e n u m e ra tio n a r e a ( th is b e in g a n e x tr e m e ly
e f fic ie n t m a n u a l p r o c e s s , a s n o te d in C h a p te r 3) a n d th e m e tr ic c o o rd in a te s
a n d e n u m e ra tio n a r e a c o d e s of th e c e n tr o id s a r e r e c o r d e d s e m i- a u to m a tic a lly .
R e c o r d s f r o m r u r a l a r e a s a r e a s s ig n e d to th e m e tr ic c o o rd in a te v ia th e
1. Io n 1969, S ta tis tic s C an a d a 1 9 7 2 a , 1972b.
112
to p o lo g ic a l c o d e of th e e n u m e ra tio n a r e a n u m b e r.
D e riv in g th e n o n - g r a p h ic
to p o lo g ic a l c o d e s a n d m e tr ic c o d e s f o r b o th u r b a n a n d r u r a l a r e a s i s a slo w ,
s e m i - a u to m a tic p r o c e s s , w h ich i s c h a r a c t e r i s t i c of th e c a te g o r y o f p o in t
s to r a g e s y s t e m s .
T h e F R IS s y s te m , f o r e x a m p le , w h ich u s e s an a p p ro a c h
s i m i l a r to GRDSR f o r a s s ig n m e n t to r u r a l a r e a c o o r d in a te s , b u t c a r r i e s it
to th e le v e l o f la n d o w n e rs h ip p a r c e ls , h a s r e q u i r e d s ix tw o - m a n te a m s of
d ig i tiz e r s to c o p e w ith th e d a ta a t a r a t e of a p p ro x im a te ly 3 0 ,0 0 0 p a r c e ls
p e r y e a r , a n d it i s e s ti m a t e d th a t t h e r e a r e a p p ro x im a te ly 3 m illio n la n d
p a r c e l s in th e p o p u la te d p a r t s of Sw eden a lo n e th a t r e q u i r e f u r t h e r p o in t
a llo c a tio n . 1 In C a n a d a b e tw e e n 1968 a n d 1972, 14 u r b a n c e n tr e s w e r e
p a r t i a l l y c o d e d , 2 2 5 ,0 0 0 b lo c k f a c e s w e r e id e n tifie d , a n d 2 7 ,0 0 0 r u r a l
e n u m e r a tio n a r e a s w e r e coded.
p li s h th i s t a s k a r e a v a ila b le .
No m e a s u r e s of th e e f f o r t r e q u i r e d to a c c o m -
T h e a s s ig n m e n t of re c o r d s '.to th e d e r iv e d p o in t
c o o r d in a te c o d e s , h o w e v e r, i s e ffic ie n t.
T h e to t a l c o s t o f a d d r e s s s t a n d a r d i -
z a tio n , v e r i f ic a t io n , a n d c o o rd in a te a s s ig n m e n t in GRDSR is a p p r o x im a te ly
1 c e n t p e r a d d r e s s .2
T h e f i l e s t r u c t u r e 3 of GRDSR i s s tr a ig h tf o r w a r d , b u t il l u s t r a t e s how th e
e ff ic ie n c y o f s u b s e q u e n t d a ta r e t r i e v a l is d ep e n d en t o n a n a p p r o p r ia te f ile
s tru c tu re .
T h e d e c la r e d o b je c tiv e of th e GRDSR s y s t e m i s to f a c i li ta te th e
r e t r i e v a l of s u b s e ts of c e n s u s d a ta (o r o th e r d ata) b y s m a l l a r e a s .
I n v e r te d
d a ta g ro u p in g of th e b a s ic d a ta s e t p ro d u c e s 120 n a m e d , in d e x e d , s e q u e n tia l
d ata, s tr in g s (s u b s e ts ) of m ix e d - fo r m a t d a ta v a lu e s (fix e d f o r m a t w ith in e a c h
s tr in g ) .
E a c h d a ta s t r i n g i s s to r e d on a d i r e c t - a c c e s s s to r a g e d e v ic e w ith
i t s a p p r o p r i a te c o n tro l in fo r m a tio n ( h e a d e r, le v e l,4 f o r m a t, le n g th , an d s o
fo r th ) .
T h e in t e r n a l in d e x (c a lle d th e d a ta d ir e c to r y ) l i s t s th e b lo c k fa c e
p o in t c o o r d in a te s a n d u s e s in t r a - d a ta - e le m e n t p o in t e r s th a t r e l a t e th e
c o o rd in a te p o in ts to in d iv id u a l d a ta v a lu e s .
f o r e a c h c ity .
O ne d a ta d ir e c to r y i s c r e a te d
T h e a d v a n ta g e of th e d a ta p lu s p o in te r in d e x (d a ta d ir e c to r y )
i s th a t o n ly th e r e q u i r e d s tr in g s a r e a c c e s s e d f o r e a c h r e t r i e v a l r e q u e s t.
W ith in th e s tr in g , o n ly th e r e q u i r e d e le m e n ts a r e a c tu a lly r e a d .
T h e d a ta
d i r e c t o r y i t s e l f i s in d e x e d b y th e q u e r y a r e a l i b r a r y (Q AL), w h ich c o n s is ts
of n a m e d s e t s o f p o in te r s d e riv e d f r o m th e d a ta d ir e c to r y .
T h e n a m e s o f th e
p o in te r s e t s in th e Q A L h e n c e d efin e s p e c if ie d a r e a s f o r d a ta r e t r i e v a l an d
c a n b e u s e d a s s ta te m e n ts in th e r e t r i e v a l c o m m a n d la n g u a g e (T A R E L A ).
1.n C rip p s 1970. 2. S ta t is tic s C a n a d a 1972b.
f o r e x p la n a tio n of " le v e l" .
3. P o d e h l 1972a.
4 . See p. 113
113
R e t r ie v a l1 i s lim ite d to g a th e r in g s p e c if ic d a ta v a lu e s f o r s p e c if ie d p o in ts.
No o th e r f o r m of d a ta m a n ip u la tio n in th e s p a ti a l s e n s e is p o s s ib le .
A re a s
a r e s p e c if ie d f o r r e t r i e v a l b y a n y n a m e d s e t of p o in t e r s in th e Q A L , o r b y a
s e t of p o in te r s g e n e ra te d b y m a tc h in g th e d a ta d ir e c to r y w ith a m e tr ic a lly o r
to p o lo g ic a lly d efin e d r e t r i e v a l a r e a b y a p o in t-in -p o ly g o n r o u tin e (P IP A ).
If
th e r e t r i e v a l a r e a i s to p o lo g ic a lly d e fin e d , b y s t r e e t n a m e s o r n o d e n u m b e r s ,
th e y a r e m a tc h e d a g a in s t t h e A M F to p ro d u c e c o o r d in a te p o in ts w h ich a r e
u s e d to d efin e th e p o ly g o n u s e d in th e P IP A .
F o r m u la s o f g e o m e tr ic s h a p e s
c a n s im i la r l y b e u s e d t o d e fin e a r e t r i e v a l p o ly g o n .
E a c h s e t of p o in te r s
g e n e r a te d b y s u c h r e q u e s t s i s n a m e d a n d a d d e d to a te m p o r a r y o r p e rm a n e n t
f o r m of th e Q A L ; th u s a " l i b r a r y " of f r e q u e n tly u s e d r e t r i e v a l a r e a s i s on
h a n d an d p r e v io u s ly s p e c if ie d a r e a s n e e d n o t b e re s p e c if ie d .
D a ta v a lu e s a r e n a m e d in a d a ta d ic tio n a r y , a n d th e n a m e s c a n b e u s e d a s
s ta te m e n ts in T A R E L A .2
A s th e d a ta s t r i n g s a r e to s o m e e x te n t h i e r a r c h i c a l
(s o m e c o n ta in d a ta r e l a ti n g to h o u s e h o ld s , s o m e to p e r s o n s , a n d s o f o r th ) ,
t h e i r " le v e l" i s c o d e d in th e s t r i n g f il e a n d th e f il e s y s t e m (STA TPA K 3) a llo w s
th e in t e r n a l g e n e ra tio n of i n t e r - f i l e p o in t e r s to p e r m it to p o lo g ic a lly d ir e c te d
s e a r c h (fo r e x a m p le , f o r v a lu e s a tta c h e d to s p e c if ic p e r s o n s w ith in c e r ta in
h o u s e h o ld s ).
T h is a g a in im p r o v e s th e s e a r c h e ffic ie n c y o f th e s y s te m .
O u tp u t f r o m m o s t r e q u e s t s i s g e n e ra te d in th e f o r m of ta b le s .
V a lu e s f o r s p e c ifie d c o o rd in a te p o in ts c a n b e fe d (v ia a p r o g r a m c a lle d
M A PPA K ) to SYM AP f o r d is p la y .
T h e A M F ca n b e a u to m a tic a lly p lo tte d
b y a p r o g r a m n a m e d M A P.M AK ER.
O v e rh e a d c o s ts a r e in v o lv e d in e x t r a c ti n g a r e a d e fin itio n s f r o m Q A L , in
a n a ly s in g th e T A R E L A r e q u e s t , an d in th e c o m p ila tio n a n d lin k in g -e d itin g
phases.
T h e e x e c u tio n c o s ts a r e c lo s e ly d ep e n d en t on th e n u m b e r o f y a lu e s
r e t r i e v e d f r o m th e s t r in g s .
T y p ic a l ta b u la tio n s ra n g e f r o m $30 to o y e r $100.
T h e c o n trib u tio n s of s y s t e m s in th e c a te g o r y il l u s t r a t e d b y GRDSR r e s t in
t h e i r a b ility to a s s ig n l a r g e d a ta s e t s to lo c a tio n id e n tif ie r s an d to s e le c t an d
r e t r i e v e s u c h d a ta e ffic ie n tly .
T h e s p a ti a l m a n ip u la tio n c a p a b ility c u r r e n t ly
in c o r p o r a te d in th e s y s t e m is t r i v i a l , e v e n ta k in g in to a c co u n t th e in h e re n t
l im ita tio n s of m a n ip u la tin g p o in t d a ta .
A n a d d itio n a l c o n s id e r a tio n is th e
r e d u c tio n of d a ta in v o lv e d in a s s ig n in g g ro u p s of p o in t d a ta ( a re a s ) to s in g le
1. S ta tis tic s C a n a d a 1972c.
2. P h ill ip s , J . 1972a. 3. P o d e h l 1972b.
114
p o in ts .
W h ile th is f a c i li ta te s s to r a g e , a s c a n b e s e e n ab o v e , it im p o s e s
s u b s t a n ti a l c o n s tr a in ts on th e u s e of d a ta .
T h e w e ll-k n o w n p o in t-in -p o ly g o n
r e t r i e v a l p r o c e s s in h e r e n tly p ro d u c e s s p u rio u s r e s u l t s w h en p o in ts a r e s u r r o g a te s f o r unknow n, i r r e g u l a r a r e a s , u n le s s s u ff ic ie n t p o in ts a r e in c lu d e d to
m in im iz e th e e d g e e ffe c t.
In a s y s t e m w h o se o b je c tiv e is to p ro d u c e s m a l l-
a r e a d a ta , th e p o in t- d a ta f o r m a t i s th u s th e m a jo r c o n s tr a in t o n r e l ia b l e
d a ta r e t r i e v a l .
T h e a c c e p ta n c e o f th i s fa c t m a y b e r e l a t e d to th e r e q u i r e m e n t s
of c o n fid e n tia lity o f c e n s u s d a ta (ev en th o u g h in th e GRDSR s y s t e m t h e r e i s a n
a d d itio n a l in b u ilt p r o c e s s , n o t d e s c r ib e d ab o v e , to e n s u r e s u c h c o n f id e n tia lity 1),
N e v e r th e le s s , th e a b ility to r e t r i e v e d a ta f r o m l a r g e f i l e s in n o t - s o - s m a l l
a r e a s s p e c if ie d b y th e u s e r i s a g r e a t s te p f o r w a r d f r o m th e s ta t e of
a v a ila b ility of c e n s u s d a ta o n ly b y p r e d e te r m in e d a g g re g a tio n s of c o n s id e r a b ly
l a r g e r s i z e , p ro v id in g th e lim ita tio n s of th e a p p ro a c h a r e u n d e rs to o d .
A s m e n tio n e d ab o v e , th e GRDSR s y s t e m u s e s p o in ts a s s u r r o g a te s f o r a r e a s
( c l u s t e r s of p o in t d a ta ), w h ic h a r e u n d e fin e d in th e r e t r i e v a l s y s t e m , w h ic h
c a n b e of w id e ly d iff e rin g s h a p e s a n d s i z e s , a n d w h ic h m a y o r m a y n o t b e
e x t e r n a ll y d e fin e d (fo r e x a m p le , m a p p ed ).
O th e r s y s t e m s in th i s c a te g o r y ,
s u c h a s F R I S a n d N C C , m e a s u r a b ly i n c r e a s e th e e f f o r t n e e d e d in i tia lly to
co d e th e d a ta b u t u tiliz e p o in ts a s s u r r o g a te s f o r s m a l l e r a r e a s (la n d p a r c e ls )
w h ic h a r e e x t e r n a ll y d e fin e d an d in s o m e in s ta n c e s a r e know n to th e s y s te m .
S om e a d d itio n a l s p a ti a l d a ta m a n ip u la tio n s a r e a ls o p o s s ib le in o th e r
s y s t e m s (fo r e x a m p le , m e a s u r in g th e a r e a s r e p r e s e n t e d b y th e d o ts in
F R IS 2) , b u t th e y a r e g e n e r a lly lim ite d .
C o m p a ris o n of th e c a p a b ilitie s of a s y s t e m in th e c a te g o r y e x e m p lif ie d b y
GRDSR w ith th e c a p a b ilitie s of m a n u a l g r a p h ic d a ta h a n d lin g te c h n iq u e s p o s e s
th e p r o b le m of s e le c tin g a s t a r t i n g p o in t f o r th e c o m p a ris o n .
T h e tr u e b a s ic
d a ta s e t s a r e , of c o u r s e , th e h a n d w ritte n c e n s u s r e t u r n s f r o m in d iv id u a l
re s p o n d e n ts .
P r i o r to 1968, th e o n ly f o r m of g r a p h ic d is p la y o f c e n s u s d a ta
in C a n a d a w a s in d iv id u a lly p ro d u c e d m a p s of c e n s u s d a ta sh o w n a s v a lu e s
w ith in c e n s u s s u b d iv is io n s a t a c o n s id e ra b ly h ig h e r le v e l o f a g g r e g a tio n
th a n e n u m e r a tio n a r e a s o r c ity b lo c k s .
W ith th e a d v e n t of l a r g e - s c a l e c o m p u te rs in th e 1960s, th e b a s ic c e n s u s d a ta
w e r e t r a n s c r i b e d in c o m p u te r - r e a d a b le f o r m to a id th e ta b u la tio n p r o c e s s .
1. P h ill ip s , J . 1972 b , M urphy 1972. 2. O ls s o n 1971.
It
115
i s th e a v a ila b ility of th a t la r g e a m o u n t of d a ta in c o m p u te r - r e a d a b le f o r m
th a t m a k e s th e d e s ig n of GRDSR p r a c t ic a l, b u t w h e th e r th e tr a n s c r i p ti o n
c o s ts sh o u ld b e a s s ig n e d to th e s y s t e m is d e b a ta b le .
T h e g ra p h ic eq u iv alen t
to th e n o n - g r a p h ic s t o r e of d a ta a s c o d e d f o r G RDSR w o u ld b e a s e r i e s of
m a p s w ith th e p o in t lo c a tio n s p lo tte d an d th e d a ta v a lu e s f o r e a c h p o in t
in d ic a te d ( e i th e r a s c l u s t e r s of v a lu e s on s h e e ts o r o n s e p a r a t e s h e e ts ,
120 in a ll) .
G iv en s u c h a g ra p h ic f il e , th e m a n u a l te c h n iq u e s th a t p a r a l le l
th o s e a v a ila b le in GRDSR w o u ld b e th e s u p e r im p o s itio n o f p o ly g o n s , an d th e
co u n tin g of d a ta v a lu e s w ith in th o s e p o ly g o n s.
T h e m a n u a l o p e r a tio n w ould
b e q u ic k e r a n d c h e a p e r th a n GRDSR if v e r y few d a ta p o in ts w e r e r e q u i r e d
f r o m v e r y few s h e e t s , b u t w o u ld r a p i d ly b e c o m e m o r e e x p e n siv e a s th e
s e a r c h a r e a o r a r e a s m u ltip lie d a n d th e n u m b e r of d a ta v a lu e s in c r e a s e d .
T h e im a g e m a n ip u la tio n c a p a b ilitie s in h e r e n t in SYM A P a r e p a r t of th e d i s p la y p o s s i b ili tie s of GRDSR.
T h e r e l a ti o n s h i p o f th o s e te c h n iq u e s to m a n u a l
p r o c e s s e s w a s d is c u s s e d in th e p re c e d in g s e c tio n of th i s c h a p te r and a p p lie s
h ere.
In g e n e ra l, th e c o n trib u tio n of s y s t e m s in th e p o in t d a ta c a te g o r y to
c u r r e n t s p a ti a l d a ta h a n d lin g r e q u i r e m e n t s l i e s in t h e i r to p o lo g ic a l
s o p h is tic a tio n r a t h e r th a n t h e i r m e t r i c f a c ility .
L IN E SEG M E N T C A TEG O RY O F SYSTEM S
T h e t h i r d c a te g o r y of s to r a g e f o r m a t c o n ta in s lin e s e g m e n t d a ta s y s te m s ,
w h ic h a r e th o s e w ith th e c a p a b ility of h a n d lin g r e a l - w o r l d d a ta e le m e n ts
s t o r e d in th e f o r m of lin e s e g m e n ts .
T h e b o u n d a ry c o n d itio n s s e p a r a tin g
lin e s e g m e n t d a ta s y s t e m s f r o m l o w e r - o r d e r s y s t e m s a r e th a t th e lin e
s e g m e n t n e tw o rk s m u s t b e d e fin e d in th e p r i m a r y f il e s t r u c t u r e o f th e
s y s t e m s a n d th a t d a ta s o r e l a te d c a n b e m a n ip u la te d an d e x t r a c te d w ith o u t
f u r t h e r n e tw o rk s p e c ific a tio n .
A lth o u g h it i s c o n v e n ie n t to e s ta b lis h th is
s u b d iv is io n in th e d is c u s s io n of c u r r e n t s y s t e m s , th e lim ita tio n s o f th e
c a te g o r iz a tio n sh o u ld b e n o te d .
F i r s t , th e h ig h e r - o r d e r s y s t e m s , s u c h a s
lin e d a ta s y s t e m s , a r e not n e c e s s a r i l y u n im o d a l.
T h e y m a y in c o r p o r a te in
t h e ir d e s ig n th e a b ility to h a n d le d a ta in f o r m a ts o th e r th a n t h e i r p r im a r y
f o r m a t a n d to ch a n g e one fo r m a t to a n o th e r.
(T he d if fe re n c e b e tw e e n th o s e
tw o fu n c tio n s sh o u ld b e r e c o g n i z e d .) S eco n d ly , a s w a s m e n tio n e d a t th e
b e g in n in g of th i s c h a p te r , th e d e v e lo p m e n t of te c h n iq u e s to h a n d le s p a tia l d ata
116
i s in a s ta t e o f t r a n s i tio n .
S y s te m s o r ig in a lly d e s ig n e d to b e u n im o d a l a r e
b e in g c h a n g e d to h a n d le a d d itio n a l d a ta fo r m a ts .
An e x a m p le o f th i s l a t t e r
ty p e of d e v e lo p m e n t i s th e F R IS s y s te m , w h ich w a s o r ig in a lly d e s ig n e d a s a
p o in t d a ta s y s t e m to lin k a d m in is tr a tiv e d a ta f il e s a n d w h ich i s now h av in g
a d d e d to it th e c a p a b ility of h a n d lin g s tr a i g h t lin e s e g m e n ts in n e tw o rk s .
In
th e i n t e r im , th e g e n e r a l g ro u p in g of s y s te m s in to c a te g o r ie s b y p r i m a r y d a ta
f o r m a t w ill b e r e t a i n e d f o r co n v e n ie n c e of d e s c r ip tio n r a t h e r th a n a s a
p r o p o s a l f o r f o r m a l o r d e r in g .
S e v e r a l c u r r e n t s y s t e m s w e r e d e s ig n e d w ith lin e s e g m e n ts a s a p r i m a r y d a ta
s to r a g e f o r m a t.
T y p ic a l e x a m p le s a r e : SACS1 (S tre e t A d d re s s C o n v e rs io n
S y s te m , U rb a n D a ta C e n t e r , S e a ttle ); V an co u v er S y ste m 2 (C ity of V an co u v er
E n g in e e r in g D e p a rtm e n t); A U T O M A P3 (C e n tra l In te llig e n c e A g en cy , U. S.
G o v e rn m e n t); a n d D IM E4 (D ual In d ep en d e n t M ap E n c o d in g S y ste m , U . S.
B u r e a u of C e n s u s ).
T w o s y s t e m s w ill b e u s e d to il l u s t r a t e th e r a n g e of
c h a r a c t e r i s t i c s w ith in th e c a te g o r y of s to r a g e f o r m a ts u s in g lin e s e g m e n ts .
T h e D IM E s y s t e m is ty p i c a l of th e c a te g o r y in th a t it a tte m p ts to h an d le
s u b s t a n ti a l v o lu m e s of d a ta r e l a t e d to e a c h lin e se g m e n t.
T h e lin e s e g m e n ts
a r e th u s u s e d t o f o r m a s p a t i a l s t r u c t u r e to w h ic h o th e r d a ta c a n b e r e la te d .
T h e s e c o n d e x a m p le i s th e A UTO M A P s y s te m , w h ich i s ty p ic a l o f s y s te m s
d e v e lo p e d t o p ro v id e a c a p a b ility f o r m a n ip u la tin g th e im a g e s f o r m e d b y t h e
lin e s e g m e n ts .
T h e e m p h a s is of th e s e tw o ty p e s of s y s t e m i s d if f e re n t, b ut
b o th u s e lin e s e g m e n t n e tw o rk s a s t h e i r p r i m a r y file s tr u c t u r e .
B o th a r e
w e ll- d e v e lo p e d s y s t e m s a n d a r e in d a ily u s e f o r p u rp o s e s o th e r th a n th o s e
of s y s t e m d e v e lo p m e n t.
T h e f i r s t to b e e x a m in e d i s th e DIM E s y s te m .
D IM E S y s te m - E x a m p le of L in e S eg m en t C a te g o ry
T h e D IM E s y s t e m v ie w s a m a p a s a c o m b in a tio n of li n e a r g r a p h ic s an d a lp h a n u m e r ic d a ta . 5 T h e l i n e a r g ra p h ic s c a n b e d e s c r ib e d b y p o in ts a t w h ich th e
r a t e o f c h a n g e o f c u r v a t u r e of th e lin e e x c e e d s s o m e g iven g o u n d s.
T h e se
p o in ts c h a r a c t e r i z e in a b s t r a c t f o r m th e s tr u c t u r e of th e g ra p h , a s tr u c t u r e
d e te r m in e d e n t ir e l y b y im p lie d m e t r i c - f r e e re la tio n s h ip s .
DIM E to p o lo g ic a l
co d in g b e g in s w ith d iv is io n o f th e a r e a to b e c o d e d in to a n e x h a u s tiv e an d
m u tu a lly e x c lu s iv e s e t of b o u n d ed re g io n s .
a u n iq u e n o m in a l co d e .
E a c h of th e s e r e g io n s i s a s s ig n e d
R e g io n s m a y h a v e s in g le o r m u ltip le b o u n d a rie s .
1. C a lk in s 1967, B a r b 1968. 2 . C ity of V an co u v er 1965. 3. S ch m id t, W. 1969.
4. U. S. B u r e a u o f C e n s u s 1972.
5. C o rb e tt an d F a r n s w o r th 1971.
117
T h is d iv is io n r e q u i r e s th a t a n a r e a to b e c o d e d b e t r e a t e d a s a s in g le , s im p ly
c o n n e c te d s u r f a c e .
T h e b o u n d a r ie s b e tw e e n r e g io n s th e n f o r m th e m in im u m
lin e (s e g m e n ts ) n e tw o rk w h ic h m u s t b e coded.
A ny a d d itio n a l lin e s ( in t e r io r
to a s in g le re g io n ) m a y a l s o b e c o d e d a s th e a p p lic a tio n r e q u i r e s .
A ll p o in ts (nodes) w h e re li n e s m e e t a r e th e n a s s ig n e d uniq u e n o m in a l c o d e s.
T h e m in im u m co d in g f o r e a c h s e g m e n t th e n c o n s is ts of fo u r n o m in a l c o d e s:
one f o r e a c h e n d p o in t a n d one f o r e a c h s id e .
S ince no s e g m e n t m a y c r o s s
a n o th e r , a s id e o f a s e g m e n t is e n t ir e l y in one a n d o n ly one re g io n .
T h e s e q u e n tia l a r r a n g e m e n t of th e tw o node c o d e s w ith in th e lin e s e g m e n t
r e c o r d i s u s e d to s p e c if y o rie n ta tio n .
A s e g m e n t i s c o n s id e r e d to b e o r ie n te d
aw ay f r o m th e f i r s t a n d to w a r d th e s e c o n d n ode.
T h is o r ie n ta tio n m a y b e
e n t ir e l y a r b i t r a r y , b u t o n c e s e t dow n it d e t e r m i n e s th e o r d e r of th e r e g io n
c o d e s , th e f i r s t of w h ic h i s th a t of th e le f t s id e of th e s e g m e n t, th e s e c o n d
th e r ig h t s id e .
N o rm a lly th e r e g io n b o u n d a ry lin e s a r e s t r e e t s a n d th e r e f o r e
it is u s e fu l to r e c o r d s t r e e t n a m e s a n d a d d r e s s r a n g e s a s a d d itio n a l n o m in a l
c o d e s , an d to b r e a k up th e b o u n d a r ie s b y s t r e e t n a m e s .
A w id e v a r i e ty of
o th e r n o m in a l c o d e s ca n b e a s s ig n e d a n d r e l a t e d to th e n o d e s , th e s e g m e n ts ,
o r th e s id e s ( a r e a s ) .
fo r m a t.
T h e r e s u lt in g in d iv id u a l lin e s e g m e n ts a r e in fix e d
T h e c o n n e c tiv itie s th a t a r e s p e c ifie d d ep e n d on th e s e le c tio n o f
n o m in a l c o d e s w h ic h a r e r e c o r d e d a s p a r t of e a c h r e c o r d , b u t in e s s e n c e ,
tw o n e tw o rk s a r e d e s c r ib e d .
O ne n e tw o rk i s th a t of th e s e g m e n ts ' c o n n e c tin g
p o in ts , th e o th e r th a t of th e s e g m e n ts ' c o n n e c tin g (s e p a ra tin g ) r e g io n s .
p r in c ip le of d u a lity le a d s to s o m e e ffic ie n t i n t e r n a l e d itin g c h e c k s .
The
The
m a in e d it ro u tin e of th e D IM E s y s t e m is th e p r o g r a m (KI R C H O F F ) th a t u s e s
th e K irc h o ff a lg o r ith m f o r d e te r m in in g th e c o n n e c tiv ity of th e g ra p h .
A f te r
a s s e m b lin g a l l s e g m e n ts w ith a p a r t i c u l a r re g io n co d e (on e i th e r s id e ) , o ne
m u s t b e a b le to f o r m o n e o r m o r e c lo s e d c h a in s w ith s e g m e n ts c h a in e d
to g e th e r b y th e n o d e co d e .
If a n y b o u n d in g s e g m e n t h a s b e e n o m itte d , o r
i f a n y co d e h a s b e e n r e c o r d e d in c o r r e c tl y , o r if th e o rie n ta tio n i s in c o r r e c t
on an y s e g m e n t, th e n th e c h a in in g w ill f a il.
S im ila r ly , one c a n a s s e m b l e a l l
s e g m e n ts w ith a g iv e n n o d e co d e an d t r y to c o n s tr u c t a c h a in a ro u n d th e n o d e
w ith th e s e g m e n ts c h a in e d on re g io n co d e s.
i f t h e r e a r e no d u p lic a te co d e s.
N o d es m u s t be s in g ly b o u n d ed
118
T h e f ile c a n b e m e tr ic a lly c o d e d b y ad d in g th e c o o rd in a te s o f n o d e s to th e
segm ent re c o rd s.
Co o r d in a te s a r e a d d e d to th e f il e s o n ly a f t e r a h ig h
le v e l of in t e r n a l to p o lo g ic a l c o n s is te n c y h a s b e e n ac h ie v e d .
T h e D IM E s y s t e m h a s b e e n d e v e lo p e d b y th e U. S. B u re a u o f th e C e n s u s .
It
h a s tw o s ig n ific a n t a d v a n ta g e s th a t a r e p a r t ic u l a r ly v a lu a b le , one o f w h ich
a r i s e s f r o m th e to p o lo g ic a l n a tu r e of i t s co d in g a n d th e o th e r f r o m i t s c e n s u s
o r ig in .
T h e s iz e of th e U n ite d S ta te s h a s in h ib ite d th e d e v e lo p m e n t o f a
u n if o r m n a tio n a l g r id th a t w o u ld s u p p o r t a m a p f il e e n c o d ed p r i m a r i l y b y
t r a c in g .
A ny in f o rm a tio n s y s t e m th a t i s c r e a te d on a g e o g r a p h ic a l b a s i s a t
p r e s e n t h a s to re c k o n w ith s o u r c e d a ta of a v a r i a b le a n d u n c e r ta in q u a lity .
H e n c e , t h e r e a r e s tr o n g a d v a n ta g e s in h e r e n t in a s p a ti a l d a ta s y s t e m w h ich
c a n e x p lo it to p o lo g ic a l r e l a ti o n s h i p s to th e f u ll e s t e x te n t.
T h e D IM E co d e d d a ta s e t i s a m e n a b le to v a r io u s ty p e s of f il e s t r u c t u r e , th e
c h o ic e o f w h ic h d e p e n d s u p o n th e p a r t i c u l a r a p p lic a tio n .
b y t h r e e e x a m p le s b elo w .
T h is i s il lu s tr a t e d
T h e U. S. B u r e a u of C e n s u s b a s ic a ll y u s e s a
p o s ta l c e n s u s f o r i t s u r b a n a r e a s (at l e a s t 60% of a l l h o u s e h o ld s in th e
U n ite d S ta te s re s p o n d in th a t m a n n e r .) T h is le d to th e e a r l y d e v e lo p m e n t of
l i s t i n g s in c i tie s of p o s ta l a d d r e s s e s th a t w e r e g ro u p e d b y b lo c k f a c e s .
E a c h b lo c k f a c e f i l e in th i s a d d r e s s l i s t (ACG, a d d r e s s co d in g guide)1 i s
id e n tifie d b y s t a t e , co u n ty , c e n s u s d i s t r i c t , c ity , z ip n u m b e r, s t r e e t s e g m e n t
n u m b e r, s t r e e t a d d r e s s b u ild in g n u m b e rs (a t e a c h en d ), a d m in is tr a tiv e co d e ,
an d an o r d e r n u m b e r.
U. S. A.
A CG f i l e s h a v e b e e n e s ta b lis h e d f o r 225 c i tie s in th e
T h e lin e s e g m e n t D IM E r e c o r d s ca n b e s e q u e n tia lly a r r a n g e d b y
n o d e n u m b e r s w ith in s t r e e t n a m e s .
T h is s te p p ro d u c e s tw o l i s t s of b lo c k
n u m b e r s , one f o r e a c h s id e of th e s t r e e t .
T h e c e n su s re c o rd s (ad d ress
c o d in g g u id e ), c o d e d b y s t r e e t a d d r e s s a n d b lo c k c o d e s , c a n th e n b e m a tc h e d
in to th e s e g m e n t r e c o r d s b y m a tc h in g s t r e e t n a m e s a n d b lo c k c o d e s , u s in g
ADM A TCH o r U N IM A TCH p r o g r a m s .2 H ence, a ll in d iv id u a l c e n s u s r e c o r d s
c a n b e s p a ti a ll y a s s ig n e d to lin e s e g m e n ts w ith in th e c ity c o n c e rn e d .
T h e D IM E a p p ro a c h a llo w s c o lla tio n of s e p a r a t e ly e s ta b lis h e d e x te r n a l
in d e x e s s u c h a s c ity d i r e c t o r i e s 3 w ith th e DIM E f ile it s e lf , on th e b a s i s of
s tr e e t nam es.
A c ity d ir e c to r y file c o n s is ts of an a d d r e s s co d in g of c o n ti-
g uous s e g m e n ts w ith in s t r e e t n a m e w ith id e n tific a tio n of in te r s e c tio n s t r e e t s .
T h e DIM E d a ta s e t i s s e q u e n tia lly a r r a n g e d b y n o d e n u m b e rs w ith in s t r e e t
1. U. S. B u re a u of C e n s u s 1971a.
C e n s u s 1971b.
2. J a r o 1972a, 1972b.
3. U. S. B u r e a u o f
119
n a m e s , a s d e s c r ib e d in th e p re v io u s e x a m p le .
T h e r e s u lt in g c h a in of no d e
n u m b e rs i s u s e d a s an in d e x to r e t r i e v e th e n a m e s of in t e r s e c ti n g s t r e e t s
f r o m th e o r ig in a l f il e a n d a d d th e m to th e new li s t .
T h e r e s u ltin g f il e is in
e s s e n ti a ll y th e s a m e s t r u c t u r e a s th e c ity d ir e c to r y , a n d it i s p o s s ib le to
c o lla te th e tw o f il e s on th e b a s i s of s t r e e t s e g m e n ts b e tw e e n i n t e r s e c ti o n s .
T h e th i r d e x a m p le c o n c e r n s th e c o lla tio n of tw o DIM E f il e s f o r th e s a m e a r e a ,
w h ic h h a v e b e e n c o d e d f o r d iffe re n t p u r p o s e s an d c o n ta in d if f e re n t c o d e s.
It
is a s s u m e d th a t th e tw o e n c o d in g s a r e in d e p en d en t a s to no d e n u m b e rin g ,
a n d th a t th e a r e a c o d e s r e c o r d e d a r e d iff e re n t in e a c h c a s e (th e tw in c i tie s
p ro b le m ) .
T h e c o lla tio n p r o c e e d s b y a s s e m b lin g th e s t r e e t n a m e s a t e a c h
n o d e in d e p e n d e n tly f o r e a c h f il e , an d th e n c o m p a rin g th e g ro u p s o f n a m e s to
d e v e lo p c o rre s p o n d e n c e b e tw e e n n o d e n u m b e rs in b o th f i l e s .
E v e n if b o th
f i l e s c o n ta in c o o r d in a te s , th e to p o lo g ic a l a p p ro a c h f o r d e v e lo p in g c o r r e s p o n d en c e i s p ro b a b ly a m o r e r e l ia b l e p r o c e d u r e th a n m a tc h in g c o o r d in a te s ,
g iv e n th e in e v ita b le d if f e re n c e s in c o o rd in a te re a d in g s f r o m tw o in d e p e n d e n t
m aps.
T h e DIM E s y s t e m h a s i t s d is a d v a n ta g e s .
I t i s o f v e r y lim ite d u s e f u ln e s s in
r u r a l a r e a s , a s th e r u r a l r o a d n e tw o rk le a v e s i n t e r s t i t i a l a r e a s p o o r ly
d if f e re n tia te d
a n d r u r a l p o s ta l a d d r e s s e s a r e v e r y d iffic u lt to a llo c a te to
s p e c ific lin e (ro ad ) s e g m e n ts .
T h e ACG d o e s n o t e x is t in r u r a l a r e a s .
T h e re
i s c o n s id e r a b le d iffic u lty in r e l a ti n g th e DIM E f il e to c e r t a i n k in d s o f m a p s ,
s u c h a s c o n to u r m a p s , w h ic h c a n o n ly b e c o lla te d on a c o o rd in a te b a s is .
T h e c o s t of c r e a tin g a D IM E f ile , in c lu d in g th e c o o rd in a te f il e , is. a p p r o x im a te ly 50 to 70 c e n ts p e r b lo c k .
T h is in c lu d e s th e u p d a tin g a n d c o r r e c tio n
of th e a v a ila b le m a p s , co d in g of th e n o d e s , a llo c a tio n of s t r e e t s e g m e n t
d e s c r ip tio n s , c a r d p u n c h in g a n d t r a n s f e r to m a g n e tic ta p e , a v a lid ity c h e c k
on th e f il e , a n d th e a d d itio n of c o o rd in a te s .
c o m p u te r to o p e r a te e ffic ie n tly .
I t u s u a lly r e q u i r e s a l a r g e - s c a l e
H o w e v e r, th e e d its w ill ru n o n a n IB M 3 6 0 /4 0
w ith a s l i t t l e a s 32K b y te s of s to r a g e .
U n d o u b ted ly a m a jo r b e n e fit of a n e s ta b lis h e d file in th e c a te g o r y o f s y s t e m s
lik e D IM E i s th e s u b s e q u e n t a b ility to c o lla te s p a tia lly th e d a ta s e t s o f i n t e r e s t
to a n in v e s tig a to r .
A n e x c e lle n t e x a m p le of th is i s th e D IM E -b a s e d h e a lth
in fo rm a tio n s y s t e m 2 (HIS) e s ta b lis h e d in New H av en , C o n n ., U . S .A .
1. O b s e r v a to ire É co n o m iq u e Mé d i t e r r a n ée n 1971.
1970a, 1971c.
N e a r ly
2. U. S. B u r e a u of C e n s u s
120
300 s e t s of d a ta it e m s f r o m s u c h s o u r c e s a s th e C e n s u s F i r s t C o u n t S u m m a ry
T a p e s , C ity V ita l R e c o r d s , a n d th e M en ta l R e ta r d a tio n R e g i s t e r w e r e lin k e d
th ro u g h A DM ATCH a n d s u m m a r iz e d b y b lo c k g ro u p .
C o r r e la tio n a l, f a c to r ,
an d f u r t h e r m u ltiv a r ia te a n a ly s e s w e r e p e r f o r m e d on th e d a ta to p ro d u c e a
few c o n s tr u c ts o r ty p o lo g ie s . 1 T h e r e s u lt in g ty p o lo g ie s th e m s e lv e s and m a p s
d is p la y in g w h ich b lo c k g ro u p s a r e ty p ic a l f o r a g iv e n ty p o lo g y (th a t i s , w h ich
b lo c k g ro u p s r a n k in th e to p q u a r t ile am o n g a l l th e b lo c k g ro u p s w ith r e s p e c t
to th i s typology) w e r e p ro d u c e d f o r c ity h e a lth s e r v ic e p la n n in g .
A g e n e ra lly
e q u iv a le n t m a n u a l p r o c e s s c o u ld b e c o n s id e re d to b e th e m a n u a l a llo c a tio n
o f th e s e le c te d d a ta v a lu e s id e n tif ie d b y s t r e e t a d d r e s s e s to c ity b lo c k s
(o r s u b je c tiv e ly d efin e d c ity z o n e s) w ith s u b s e q u e n t m a n u a l co u n tin g and
s u m m a r y le a d in g to th e e q u iv a le n t s t a t i s t i c a l a n a ly s is , fo llo w e d b y g e n e ra tin g
a p p r o p r ia te m a p s of th e r e s u l t s .
A n a l te r n a t iv e m ig h t b e to p lo t e a c h d a ta
s e t a s p o in ts on a c ity m a p , w ith s u b se q u e n t v is u a l in t e r p r e ta tio n of p o in t
c lu s te r c h a ra c te ris tic s .
E i th e r a p p ro a c h w o u ld in v o lv e e x te n s iv e m a n u a l
e f f o r t a n d i t ca n b e n o te d th a t d e s p ite th e lo n g - t e r m a v a ila b ility o f th e
s t a t i s t i c s c o n c e rn e d , no a tte m p t h a s b e e n m a d e to c a r r y o u t th i s ty p e of
s p a ti a l a n a ly s is b y m a n u a l m e th o d s (though s u c h a d e c is io n i s in flu e n c e d b y
th e le v e l of c ity m a n a g e m e n t p r o c e s s e s a s w e ll a s th e c o s t o f c a rto g r a p h ic
te c h n iq u e s ).
T h e m o s t s o p h is tic a te d s p a ti a l a n a ly s is te c h n iq u e s b a s e d o n th e n e tw o rk s
d efin e d in a D IM E s y s t e m a r e in c o r p o r a te d in a p r o g r a m know n a s th e
c o m p u te r iz e d r e s o u r c e a llo c a tio n m o d e l (CRAM ).
CRA M 2 is a g e n e ra liz e d
s y s t e m f o r d e te rm in in g th e s e r v ic e a r e a s f o r a s e t of f a c i li ty lo c a tio n s .
In
it s m o s t g e n e r a l f o r m , s e r v i c e a r e a s a r e c o n s tr a in e d b y f a c i li ty c a p a c itie s
an d t r a v e l ti m e s .
G iven d a ta on d e m a n d an d f a c i li ty c a p a c ity , th e p r o b le m s
th a t c a n b e a tta c k e d th ro u g h C RA M r u n f r o m s im p le f ix e d - s o u r c e d is tr i c ti n g
p r o b le m s , s u c h a s a llo c a tio n o f s c h o o l d i s t r i c t b o u n d a rie s , p a r k p la n n in g ,
an d s i t e lo c a tio n , to m u c h m o re c o m p lic a te d p ro b le m s o f e m e r g e n c y v eh ic le
ro u tin g , d e liv e r y o r b u s ro u te p la n n in g , an d f re e w a y lo c a tio n s tu d ie s .
CRAM
u s e s a m o d ifie d v e r s io n of th e M o o re s h o r te s t p a th a lg o r ith m 3 to do it s
g e o g ra p h ic a n a ly s is ; th e m o d ific a tio n c o n s is ts of ch a n g in g M o o r e 's te c h n iq u e
o f fin d in g th e s h o r te s t p a th b e tw e e n p o in ts to one of v ie w in g th e n e tw o rk a s a
1 . A ty p o lo g y in th i s s e n s e i s a s y n th e s is of m a n y it e m s , o r d e r e d lo g ic a lly b y
t h e i r c o n trib u tio n to th e w h o le. 2. U. S. B u re a u of C e n s u s 1971d.
3 . F a r n s w o r t h 1970.
121
s e t of in te rc o n n e c te d lin k s , th e c o n n e c tio n s b e in g n o d e s .
T h is a p p ro a c h
f i t s th e a lg o r ith m to th e p r i m a r y DIM E file s t r u c t u r e a n d b r in g s s o m e
a d v a n ta g e s in th e a llo c a tio n of d em an d , b e c a u s e d is a g g r e g a tio n o f p e rso n s
(dem and) to lin k s i s m o r e r e l ia b l e th a n d is a g g re g a tio n to n o d e s , a s lin k s
h a v e le n g th a n d th e d is a g g r e g a tio n m a y b e v a r i e d a c c o rd in g to le n g th , b u t
th i s ca n n o t b e done w ith n o d e s .
In m a n u a l t e r m s , th e u s e of g ra p h ic s to r a g e
a s a s o u r c e of d a ta f o r s u c h s p a tia l a n a ly s is w o u ld im p ly th e m a n u a l m e a s u r e m e n t of le n g th o f a l l r e l e v a n t s t r e e t s e g m e n ts on a s t r e e t m a p , th e m a n u a l
a llo c a tio n of p o p u la tio n d a ta f r o m in d iv id u a l c e n s u s (o r o th e r) r e c o r d s b y
s t r e e t a d d r e s s to th e lin e s e g m e n ts , a n d th e id e n tif ic a tio n an d c a lc u la tio n
of s h o r t e s t p a th s in th e s im p le c a s e of a fix e d f a c ility .
I t is d o u b tfu l if th e
it e r a t i v e p r o c e s s e s of o p tim iz in g c o lle c tio n r o u te s o r a llo c a tio n o f m u ltip le
f a c i l i t y lo c a tio n s w o u ld b e a tte m p te d q u a n tita tiv e ly b y m a n u a l m e th o d s .
It
i s m u c h m o re p r o b a b le th a t e s tim a tio n , c o u p le d w ith a lim ite d a m o u n t of
m a n u a l m e a s u r e m e n t, w o u ld b e e m p lo y e d to a v o id a n in c a lc u la b le am o u n t of
m a n u a l e f fo r t.
In e i th e r of th e s e m a n u a l a p p r o a c h e s to n e tw o rk a n a ly s is ,
a h ig h p e r c e n ta g e of th e m a n u a l ta s k s a r e of a h ig h o r d e r b e c a u s e th e d a ta
r e q u i r e d a r e in h e r e n t in th e g r a p h ic file s t r u c t u r e , r a t h e r th a n b e in g e x p lic itly
w r itt e n in it.
M o re d i r e c t c o m p a r is o n b e tw e e n m a n u a l te c h n iq u e s a n d c o m p u te r - a id e d
te c h n iq u e s r e l a t e d to th e D IM E ty p e ca n b e m a d e f r o m a n e x a m p le o f th e
s i m p l e r s p a ti a l d a ta m a n ip u la tio n t a s k s .
U sin g th e DACS p r o g r a m 1 (DIME
A r e a s - C e n tr o i d S y ste m ), th e s iz e of c ity b lo c k s , c e n s u s t r a c t s , o r o th e r
a r e a s n o m in a lly d e fin e d in a m e tr ic a lly c o d e d D IM E f il e c a n b e c a lc u la te d .
T h is w o u ld c o m p a re w ith m e a s u r e m e n t o f th e s a m e a r e a s b y d ot g r id o r
p la n im e te r on th e g r a p h ic v e r s io n of th e m a p .
S im ila r ly , b y th e DACS
p r o g r a m , th e p o s itio n of a r e a c e n tro id s c a n b e a llo c a te d an d t h e i r c o o r d in a te s c a lc u la te d .
T h is w o u ld c o m p a re w ith th e e ffic ie n t p r o c e s s o f v is u a l
a r e a c e n tr o id a llo c a tio n c o u p le d w ith th e r e l a ti v e ly slow m a n u a l p r o c e s s o f
d e te r m in in g c o o rd in a te v a lu e s f r o m a n o v e r la id g r id .
T y p ic a l f ig u r e s f o r
th e c o m b in e d c o m p u te r - a id e d a r e a c a lc u la tio n a n d c e n tro id a llo c a tio n
p r o c e s s (p ro d u c in g a li s t in g of a r e a id e n tif i e r , s iz e , an d c e n tr o id c o o rd in a te s )
a r e : f o r 288 b lo c k s in A k ro n , O hio, 2 1 .6 m in of IB M 36 0 /4 0 cp u ti m e a t a
1. M e y e r 1972.
2. W h ite, M. S. 1973.
122
to t a l c o s t of $ 4 . 00; a n d s im i la r l y f o r a p p ro x im a te ly 5 ,0 0 0 b lo c k s in New
H av en , C o n n ., 1 a to t a l c o s t of a p p ro x im a te ly $ 8 0 . 00.
(C o s ts a r e n o t q u ite
l i n e a r a s th e p r o c e s s in v o lv e s b o th s o r tin g an d c a lc u la tio n , a n d th e c o s t of
th e s o r tin g r i s e s f a s t e r th a n th e c o s t of th e c a lc u la tio n .)
I t i s a l s o p o s s ib le ,
t h e r e a f t e r , u s in g D IM E s y s t e m c o lla tio n p r o c e d u r e s , to a llo c a te th e
d a ta s u m m a r iz e d b y b lo c k s o r o th e r a r e a s to s u c h c a lc u la te d c e n tr o id s .
P o in t- in - p o ly g o n r e t r i e v a l c a n b e c a r r i e d out s u b s e q u e n tly o n s u c h p o in t
d a ta (in e x a c tly th e s a m e m a n n e r a s th e GRDSR p o in t d a ta s y s t e m d e s c r ib e d
a b o v e , a n d w ith a l l th e c o n s tr a in ts in h e r e n t in p o in t d a ta s y s t e m s ap p ly in g
to th e p r o c e s s ) .
E v e n a s s u m in g a co n v e n ien t w ay of m a n u a lly a llo c a tin g
d a ta s e t s to g r a p h ic a lly s to r e d p o in ts , th e m a n u a l p r o c e s s o f s u c h po ly g o n
o v e r la y a n d p o in t c o u n tin g r e q u i r e s c o n s id e ra b le m o to r e f f o r t if th e a r e a
c o n c e rn e d i s l a r g e o r if th e p r o c e s s h a s to b e r e p e a te d f o r v a r i o u s ty p e s o f
p olygon.
A s a c o m p le m e n t to th e DIM E ty p e of s y s te m , w h ic h u s e s a lin e n e tw o rk
a s a b a s i s f o r m a n ip u la tin g r e l a t e d s e t s of d a ta , it is n e c e s s a r y to c o n s id e r
th e ty p e of s y s t e m th a t in c o r p o r a te s th e a b ility to p e r f o r m s p a t i a l d a ta m a n ip u la tio n s on a r e l a t i v e l y s im p le im a g e file of lin e s e g m e n ts a n d p o in ts b u t th a t
d o e s n o t p ro v id e m u ltip le lin k a g e s to r e l a te d d a ta s e t s .
A ty p i c a l e x a m p le
o f th i s p a r t of th e lin e s e g m e n t c a te g o r y of s y s t e m s i s th e A U TO M A P2
s y s t e m of th e C e n t r a l In te llig e n c e A g en cy , U. S. A.
A U T O M A P S y s te m - E x a m p le of L in e S egm ent C a te g o ry
T h e A U T O M A P s y s t e m c o n c e rn s i t s e lf w ith th e e x t r a c ti o n o f s im p le lin e an d
p o in t d a ta f r o m e x is tin g m a p s , w ith t h e i r s to r a g e in a n o n - g r a p h ic f o r m , an d
w ith th e a b i lit y to s e le c t an d m a n ip u la te th e s e t o r a s u b s e t o f th e n o n - g r a p h ic
im a g e s (im a g e m a n ip u la tio n te c h n iq u e s ) in q u ite a c o m p re h e n s iv e w ay b e f o r e
d is p la y in g th e m a g a in in g ra p h ic f o r m .
I t d o e s n o t, a s f a r a s i s p u b lish e d ,
h a v e a n y e x te n s iv e a b ility to e x t r a c t d a ta f r o m th e n o n -g r a p h ic s to r a g e if
th e y a r e n o t a l r e a d y w r itt e n in th e f il e (s e e d a ta e x t r a c ti o n te c h n iq u e s ).
T h e g r a p h ic s o u r c e d a ta o r ig in a lly u s e d w e r e th e U. S. N av y O c e a n o g ra p h ic
12 S h eet M ap " T h e W o rld " (1:12, 2 3 3 ,0 0 0 s c a le ) a n d th e U. S. A ir F o r c e
P la n n in g C h a r t " A n ta r c tic a " A SC -6 (1 :9 ,0 0 0 ,0 0 0 s c a le ) .
T h e d a ta e le m e n ts
th a t w e r e n o n - g r a p h ic a lly co d e d w e re lin e s e g m e n ts d e s c r ib in g in te r n a tio n a l
1. W hite, M. S. 1973.
2. S ch m id t, W. 1969.
123
b o u n d a rie s , c o a s tlin e s , r i v e r s , c o o r d in a te g r id s , an d s e le c te d p o in t d ata.
P o in t d a ta e le m e n ts a r e m e tr ic a lly co d e d b y la titu d e an d lo n g itu d e c o o rd in a te s
a n d a r e n o m in a lly c o d e d b y n a m e , ty p e of lo c a tio n , " r a n k " , m a p a r e a co d e ,
an d a c c e s s io n n u m b e r.
L in e d a ta a r e m e tr ic a lly c o d e d a n d t r a n s f e r r e d f r o m g ra p h ic s to r a g e to n o n g r a p h ic s to r a g e b y u s in g a d ig ita l lin e fo llo w e r, a T h o m p so n P F 1 0 L D S , w h ich
c r e a t e s a s t r i n g of a r b i t r a r y X , Y c o o rd in a te s f o r e a c h lin e s e g m e n t.
E ach
lin e s e g m e n t is f u r t h e r id e n tifie d b y a n u m b e r u n iq u e ly a s s ig n e d w ith in e a c h
c o n tin e n t.
T h e lin e s e g m e n ts a r e p la c e d in a v a r i a b le - f o r m a t in d e x e d
s e q u e n tia l f i l e s t r u c t u r e in o r d e r o f s e g m e n t n u m b e r.
T h e in d e x r e l a t e s th e
lin e s e g m e n t n u m b e r to a m a p a r e a co d e , a f e a t u r e ty p e co d e , an d a " r a n k "
code.
T h e " r a n k in g " co d e a llo c a te s e a c h d a ta e le m e n t to one of a h i e r a r c h a l
s e r i e s of s u b s e ts of d a ta .
T h e c o d e s a r e th u s i n t r a - f i l e p o in te r s to a n
e x t e r n a l d ir e c to r y of r a n k v a lu e s .
T h e ra n k in g c o d e c o u p le d w ith th e n a m e s
o f th e ty p e s of d a ta e le m e n t r e q u i r e d a r e th e n e c e s s a r y d a ta d e s c r i p to r
s ta te m e n ts in s u b s e q u e n t r e t r i e v a l a n d m a n ip u la tio n p r o c e s s e s .
A m a th e m a tic a l tr a n s f o r m a tio n i s s u b s e q u e n tly p e r f o r m e d o n th e lin e se g m e n t
f il e to c o n v e rt th e a r b i t r a r y c o o r d in a te s to g e o g ra p h ic c o o r d in a te s an d r a d ia n
v a lu e s .
T h e g e o g ra p h ic a l c o o r d in a te s of th e p o in t d a ta s e t s c a n s i m i l a r l y b e
t r a n s f o r m e d to r a d i a n s .
T h i s , th e n , i s th e f i r s t e x a m p le in th e s e t o f s y s te m s
d e s c r ib e d in th i s c h a p te r th a t v e n tu r e s in to an y f o r m of th r e e - d im e n s i o n a l
m e tr ic coding.
T h e s y s t e m c a n c a r r y o u t th e s e in p u t tr a n s f o r m a tio n s on
s o u r c e d a ta a r r a n g e d in p la n e g r a p h ic s to r a g e in a n y one o f f o u r c o m m o n
m a p p r o je c tio n s .
O nce th e s p a ti a l d a ta a r e o r g a n iz e d in th i s m a n n e r in th e n o n - g r a p h ic f il e ,
i t i s p o s s ib le to c a r r y o u t im a g e m a n ip u la tio n s th a t a r e b o th in t e r e s ti n g
a n d e x te n s iv e .
U sin g th e c o o r d in a te v a lu e s a n d r a d i a n v a lu e s , th e n o n -
g ra p h ic s t o r e c a n b e r e a r r a n g e d in to a n y o n e of 16 p la n e tr a n s f o r m a tio n s
b y th e CA M 1 (C a rto g ra p h y A u to m a tic M apping) p r o g r a m .
are:
1. S ch m id t, W . 1970.
T h e s e p r o je c tio n s
124
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
M e r c a to r - s p h e r e or s p h e ro id
M ille r C y lin d r ic a l - s p h e r e o r s p h e r o id
T r a n s v e r s e M e r c a to r - s p h e r e
O r ig in a l In p u t P r o je c tio n , r e g a r d l e s s of ty p e (o n e -to -o n e )
A z im u th a l E q u id is ta n t, O b liq u e - s p h e re
O rth o g ra p h ic f r o m In fin ity
E q u ir e c ta n g u la r
S te re o g r a p h ic - s p h e r e o r s p h e ro id
L a m b e r t C o n fo rm a l C o n ic w ith T w o S ta n d a rd P a r a l l e l s - s p h e r e o r
s p h e r o id
P to le m y C o n ic E q u a l I n te r v a l w ith O ne S ta n d a rd P a r a l l e l
K a v r a is k y IV C o n ic E q u a l I n te r v a l w ith Tw o S ta n d a rd P a r a l l e l s
A l b e r 's C o n ic E q u a l A r e a w ith T w o S ta n d a rd P a r a l l e l s
T r a n s v e r s e M e r c a to r S p h e ro id
G nom onic - s p h e r e
P e r s p e c t iv e f r o m a G iven A ltitu d e
A z im u th a l E q u a l A r e a
I t w ill b e r e m e m b e r e d th a t th e m a n u a l p r o c e s s of ch a n g in g m a p p r o je c tio n s
w a s e x t r e m e l y le n g th y a n d la b o r io u s a n d w a s a fu n c tio n u s u a lly u n d e r ta k e n
o n ly b y la r g e c a r t o g r a p h ic in s titu tio n s .
T h e A UTO M A P s y s t e m c a n c a r r y
o u t s u c h ta s k s w ith in a s in g le day.
A f u r t h e r in t e r e s ti n g a b i lit y i s to s e le c t s p e c ific a r e a s f o r r e t r i e v a l a n d a t
th e s a m e tim e to s p e c if y to p o lo g ic a lly th e c a te g o r ie s of d a ta th a t a r e
r e q u i r e d f o r d is p la y , a n d a ls o , if n e c e s s a r y , in c o r p o r a te a g e n e r a liz a tio n of
th e l i n e a r d a ta .
A s m e n tio n e d ab o v e , th e s e le c tio n of it e m s to b e d is p la y e d
i s b a s e d on th e c o d e s f o r d a ta ty p e an d r a n k le v e l, s u c h a s a l l to w n s (type)
of o v e r 1 0 0 ,000 in h a b ita n ts (ra n k ).
L i n e a r g e n e ra liz a tio n is a c h ie v e d b y
ig n o rin g s e g m e n t c o o r d in a te s a t s p e c if ie d i n t e r v a l s an d a s s ig n in g a f r e e - r u n
(in te rp o la te d ) p lo t te r lin e th ro u g h th e r e m a in in g p o in ts.
T h is a p p r o a c h to
li n e a r g e n e ra liz a tio n i s s im p l is tic b u t a d e q u a te f o r th e d e c is io n - m a k in g
p u r p o s e s th a t th e s y s t e m w a s d e s ig n e d to a c c o m m o d a te .
(T he c o a s t a l is la n d
p r o b le m i s d e a lt w ith b y a s im p le a l g o r ith m .) D ep en d en t o n th e r e q u i r e m e n t s
of th e u s e r , th e s y s t e m h a s th e a b ility a u to m a tic a lly to s e a r c h th e f il e , to
c a r r y out th e c a lc u la tio n s n e c e s s a r y f o r th e r e q u i r e d p r o je c tio n , s c a l e ,
a n d o u tp u t d e v ic e , a n d to f i l t e r to e lim in a te s u p e rflu o u s p o in ts .
T h is p r o c e s s
th u s n o t o n ly in c lu d e s th e im a g e m a n ip u la tio n s of th e d a ta b a s e , b u t i n c o r p o r a t e s s e le c tiv e e x t r a c ti o n a k in to th e p r o c e s s of tr a c in g s e le c te d d a ta
f r o m g ra p h ic s to r a g e .
125
T h e s y s t e m h a s th e f u r t h e r a b ility to g e n e r a te a n d d raw p r o je c tio n g r id s ,
ra n g e r in g s , a z im u th s , a n d c i r c l e s o r s p i r a l s a ro u n d a g iv e n p o in t, a n d to
s u p e r im p o s e th e s e on th e d a ta to b e d is p la y e d .
In th e s a m e m a n n e r , i t ca n
g e n e ra te a n d d ra w r e c t a n g le s , m a p b o u n d a r ie s , g r e a t c i r c le p a th s , e l lip s e s ,
a v a r i e ty of s p e c i a l s y m b o ls , m a p c e n tr e p o in ts , c o r n e r ti c k s , a n d t i tle
b lo c k s .
T h e s y s t e m e m p lo y s a l a r g e - s c a l e c o m p u te r (IBM 360 /6 5 ) an d c a n p ro d u c e
g ra p h ic o u tp u t s u ita b le f o r a v a r i e t y of o u tp u t d e v ic e s : lin e p r i n t e r , lin e
p lo t te r , a n d c a th o d e r a y tu b e .
T o do t h i s , it c a n c o n tro l a lig h t-b e a m ,
d ra w in g h e a d o n th e p lo ttin g ta b le , c o n tr o l v a r i o u s l y c o lo u r e d p e n s o n o ne
o u tp u t, a n d c o n tr o l th e s i z e a n d s la n t a t w h ic h s p e c i a l sy m b o ls a r e d raw n .
T h e tim e b e tw e e n r e q u e s t f o r d a ta a n d a fin a l m a p p lo tte d to th e s p e c i f ic a tio n s r e q u e s te d c a n ta k e a s l i t t l e a s 3 to 4 h o u r s .
T he sy ste m h a s an
e x t r e m e l y li m it e d s u ite of d a ta s e t s w ith a t o t a l n u m b e r o f p o in ts a n d lin e
s e g m e n t n o d es in th e o r d e r o f 1 0 0 ,0 0 0 ; it ca n n o t h a n d le th e p r in tin g of n a m e s
w ith an y f a c ility , a n d h a s n o c a p a b ility f o r m e a s u r e m e n t o r c o m p a r is o n of
d a ta .
T h e s y s t e m i s b y no m e a n s u n iq u e .
S im ila r a p p r o a c h e s h a v e b e e n u s e d a t
s e v e r a l a g e n c ie s , in c lu d in g th e E x p e r im e n ta l C a rto g ra p h y U n it,1 R . C. A . ,
L ondon, R o m e A i r D e v e lo p m e n t C e n te r ,2 New Y o rk , th e C a n a d ia n H y d ro g r a p h ic S e rv ic e ,3 O tta w a , th e G eo g ra p h y D e p a rtm e n t, U n iv e r s ity of
M ic h ig a n ,4 th e O n ta r io D e p a rtm e n t of H ig h w a y s,5 T o ro n to , an d th e
E le c tro m a g n e tic C o m p a tib ility A n a ly s is C e n te r ,6 A n n a p o lis, M ary la n d .
A s th e u s e of s u c h m a p c o m p ila tio n s y s t e m s in c r e a s e s , s o t h e r e w ill b e
a b u ild - u p of c a r t o g r a p h ic in f o rm a tio n in d ig ita l f o r m th a t w ill b e a m e n a b le
to s p a ti a l a n a ly s is of m a n y k in d s .
A lth o u g h th i s ty p e of a n a ly s is i s n o t th e
a im of m a n y s y s t e m s of t h i s c a te g o r y a t p r e s e n t , it m a y b e a f u tu r e b e n e fit
w h ic h f a r e x c e e d s th e c u r r e n t o b je c tiv e s of ec o n o m y an d f a c i li ty in p ro d u c in g
c a rto g r a p h ic im a g e s .
S om e li m it e d m e a s u r e m e n t an d c o m p a ris o n o f n o n -
g ra p h ic s to r a g e s a r e b e in g c a r r i e d out in s o m e r e l a t e d s y s te m s .
T h e d ig ita l
in f o rm a tio n i s , f o r e x a m p le , b e in g u s e d to c a lc u la te d is ta n c e s , a r e a s , and
v o lu m e s in v a r io u s a p p lic a tio n s .
P r o f ili n g ,7 li n e - o f - s ig h t a n a ly s is ,8 and
r a d a r - m a s k in g a n a ly s is 6 a r e a l s o b e in g c a r r i e d o u t.
.
T h e A UTOM A P s y s te m
.
1. B ic k m o r e 1971, L a n g 1971, R h in d 1971. 2. D ie llo e t a l. 1969, D ie llo 1970.
3 B oyle 1970b, 1972. 4. T o b le r 1970. 5 M cL e o d 1972. 6 E le c tro m a g n e tic
C o m p a tib ility A n a ly s is C e n te r 1969. 7. C la rk . 1970. 8. B o ehne 1967.
126
d o e s , h o w e v e r, r e p r e s e n t one s u c h s y s t e m th a t i s in d a y - to - d a y u s e f o r
p u r p o s e s o th e r th a n i t s ow n d e v e lo p m e n t.
SUMMARY
T h is c h a p te r h a s f o c u s s e d on th e lim ita tio n s an d c a p a b ilitie s o f c u r r e n t
te c h n iq u e s f o r n o n -g ra p h ic s to r a g e an d c o m p u te r - a id e d m a n ip u la tio n of
s p a ti a l d a ta .
d is c u s s e d .
T h e b a s ic a t tr ib u t e s of n o n -g r a p h ic s to r a g e w e r e b r ie f ly
G e n e ra l c a te g o r ie s o f c u r r e n t c o m p u te r - a id e d te c h n iq u e s w e r e
th e n e x a m in e d a n d t h e i r c h a r a c t e r i s t i c s il l u s t r a t e d w ith s p e c if ic e x a m p le s .
C o m p u te r -a id e d te c h n iq u e s w e r e c o m p a re d w ith m a n u a l te c h n iq u e s .
S e v e ra l
c o n c lu s io n s c a n b e d ra w n f r o m th e e v id e n c e p r e s e n te d .
A ss u m in g th a t th e l a r g e - s c a l e c o m p u te rs c o m m o n in m o s t r e s e a r c h an d
g o v e rn m e n t in s titu tio n s in th e 1970s a r e a v a ila b le to th e u s e r , th e n th e
f a c t o r th a t d e te r m in e s th e u s e f u ln e s s of c u r r e n t s y s t e m s is th e f o r m a t a n d
f il e s t r u c t u r e of th e s p a ti a l d a ta s to r e d in th e m .
T h e p r i m a r y s h o r tc o m in g
o f c u r r e n t s y s t e m s i s th e c o n s tr a in t on d e v e lo p m e n t of th e f o r m a t im p o s e d
b y th e e c o n o m ic s of t r a n s f o r m in g g ra p h ic s o u r c e d a ta to a m e t r i c a l l y co d ed ,
n o n -g r a p h ic f o rm .
In a l l s y s t e m s d e s c r ib e d th e p r o c e s s i s m a n u a l o r , at
b e s t , s e m i- a u to m a tic .
In ty p ic a l l o w e r - o r d e r s y s t e m s , e x t r e m e l y h ig h
le v e ls of m a n u a l e f f o r t a r e u s e d to c r e a te d a ta f o r m a ts w ith in h e r e n t
in fo r m a tio n l o s s , a n d f il e s t r u c t u r e s of th e s im p l e s t k in d .
In th e h i g h e r -
o r d e r s y s t e m s th e c r e a tio n of th e b a s ic m e tr ic a lly c o d e d s to r a g e f o r m a ts
in v o lv e s e f f o r t ra n g in g f r o m 5 to 50 m a n -d a y s p e r 2 0 -in . x 3 0 -in . m ap
s h e e t.
T h e e f fo rt in v o lv e d p u ts s e v e r e c o n s tr a in ts on th e am o u n t of d a ta
a v a ila b le to th e c o m p u te r.
It sh o u ld b e e m p h a s iz e d th a t th i s a p p lie s
p r i m a r i l y to th e m e t r i c a s p e c t of n o n - g ra p h ic c o d in g .
T h e m o s t s ig n if ic a n t
ad v a n c e in o v e rc o m in g th e lim ita tio n s of c u r r e n t p r a c t i c e s f o r c o n v e rtin g
g r a p h ic to n o n -g ra p h ic d a ta l i e s in th e a b ility to r e l a t e s p a ti a l to to p o lo g ic a lly
co d e d d a ta s e t s , d e v e lo p e d in th e h ig h e r - o r d e r s y s t e m s e x e m p lifie d b y
PA A S,1 A DM A TCH ,2 a n d UNIM A TCH . 3 T h e li m ita tio n on m e tr ic in p u t is
s ig n ific a n t a s it ca n h a v e th e e ffe c t, a t p r e s e n t , of r e d u c in g th e re s o lu tio n
of th e in p u t d a ta (in a n a tte m p t to r e d u c e th e in p u t e ffo rt) a n d th u s im p o s in g
s ig n ific a n t c o n tro l o v e r th e s u b se q u e n t u tility o f th e c o m p u te r - a id e d p r o c e s s .
S im ila r ly , it l i m it s th e v o lu m e of d a ta a v a ila b le to th e s y s te m , a n d th e
1. S ta t is tic s C a n a d a 1972b. 2. U. S. B u re a u of C e n s u s a s d e s c r ib e d b y J a r o
1972a. 3. U. S. B u re a u of C e n s u s a s d e s c r ib e d b y J a r o 1972b.
127
p r i m a r y a d v a n ta g e of c o m p u te r p r o c e s s in g i s i t s a b ility to h a n d le ra p id ly
l a r g e v o lu m e s o f d a ta .
C e r ta in ly , i f im p ro v e m e n ts in c u r r e n t s y s te m s a r e
to b e e x p e c te d , th e y w o u ld b e of g r e a t e s t b e n e fit in th e in p u t p r o c e s s .
In c o n t r a s t to th e li m it a ti o n s im p o s e d b y th e tr a n s f o r m a tio n o f d a ta to n o n g r a p h ic f o r m a ts , t h e r e i s a s ig n ific a n t u n d e r - u s e of c a p a c ity in s u b se q u e n t
d a ta m a n ip u la tio n a n d e x tr a c tio n .
In a l l c a te g o r ie s of s y s t e m s o f a r
d e s c r ib e d , th e f il e s t r u c t u r e s a r e a t b e s t s tr a ig h tf o r w a r d .
It a p p e a r s th a t
th e c a p a c ity of c u r r e n t (1974) l a r g e - s c a l e c o m p u te r s to m a n ip u la te d a ta is
c o n s id e r a b ly in e x c e s s of th e m a n ip u la tio n s x v o lu m e of s p a ti a l d a ta th a t
th e y a r e b e in g a s k e d to h a n d le .
T h is m a y w e ll b e a c o n s tr a in t im p o s e d b y
th e in p u t li m ita tio n s d e s c r i b e d a b o v e .
I t m a y b e a la c k o f r e q u ir e m e n t f o r
d a ta to b e m a n ip u la te d in a s o p h is tic a te d m a n n e r (th a t i s , a la c k o f u s e r
n e e d o r c o m p e te n c e ).
In a n y e v e n t, th e r e i s no e v id e n c e f r o m th e f ile
s t r u c t u r e s e x a m in e d s o f a r th a t th e y a r e d e s ig n e d to f a c i li ta te (th a t i s , to
m a k e p o s s ib le e c o n o m ic a lly ) c o m p le x s p a ti a l d a ta m a n ip u la tio n s .
T h e s e c o n s id e r a tio n s le a d to th e g e n e ra l o b s e r v a tio n th a t c u r r e n t c o m p u te r a id e d s y s t e m s a r e , to a g r e a t e x te n t, c o n c e p tu a lly e x te n s io n s of m a n u a l
p ro c e sse s.
A s m e n tio n e d a t th e b e g in n in g o f th i s c h a p te r , th e y a r e in a
t r a n s i tio n p h a s e b e tw e e n m a n u a l te c h n iq u e s a n d c o n s id e ra b ly m o r e a d v a n c e d
c o m p u te r - a id e d p r o c e s s e s , th e l a t t e r u s in g e i th e r co d e d o r n o n -c o d e d
in fo rm a tio n .
A t th e e n d of th e c h a p te r c o n c e rn in g m a n u a l te c h n iq u e s , i t
w a s n o te d th a t in c r e a s in g d a ta v o lu m e r a p id ly d e c r e a s e s th e ty p e o f m a n u a l
te c h n iq u e th a t c a n b e c o n s id e r e d e c o n o m ic a l, a n d it w a s s u g g e s te d th a t
c o m p u te r - a id e d te c h n iq u e s m ig h t p r o f ita b ly s e e k to r e d u c e m a n u a l m o to r
p r o c e s s e s a n d allow th e p r e s e n t a tio n of d a ta to a u s e r in a f o r m th a t d o e s
n o t o v e r lo a d h is c h a n n e l c a p a c ity (th e l a s t tw o s u g g e s tio n s b e in g a d ir e c t
fu n c tio n of th e v o lu m e of d a ta to b e h a n d le d ).
T h e k e y to th e u ti lit y o f
c o m p u te r - a id e d s y s t e m s i s th u s th e d e g r e e to w h ic h th e y c a n s p a tia lly
m a n ip u la te in c r e a s in g v o lu m e s of d a ta .
tw o f o r m s .
S uch s p a ti a l m a n ip u la tio n c a n ta k e
T h e f i r s t of th e s e i s th e a b ility to r e d u c e th e in fo rm a tio n
c o n te n t of im a g e s , o r r e f o r m a t th e m to f it m e n ta l in d e x e s , to th e p o in t w h e r e
t h e i r v is u a l e x a m in a tio n d o e s n o t e x c e e d h u m a n c h a n n e l c a p a c ity (so th a t
th e m a p s p ro d u c e d b e c o m e c l e a r o r a r e c o m p r e h e n s ib le to m a n k in d , b u t
128
w h e re th e s u b se q u e n t c o r r e l a ti o n s o r p a t te r n s of s p a ti a l d a ta a r e s t i l l
v is u a lly d e te r m in e d b y th e o b s e r v e r ) .
T h e s e c o n d ty p e of s p a tia l m a n ip u la -
tio n i s th e a b i lit y to r e t a i n th e to t a l in fo rm a tio n c o n te n t of th e im a g e s an d
s y s t e m a tic a lly a n a ly s e th e m n o n -v is u a lly (b e c a u se th e v o lu m e of g ra p h ic
d a ta d o e s n o t allow v is u a l in s p e c tio n ), th e n to p r e s e n t th e r e s u l t s o f s u c h
a n a ly s is to th e u s e r .
T h e lo w e r o r d e r of c u r r e n t s y s te m s a n d th e h ig h e r o r d e r o f im a g e m a n ip u la tio n s y s t e m s (s u c h a s SYMVU,1 O B LIX , 2 A U T O M A P 3) m a k e t h e i r
g r e a t e s t c o n trib u tio n in th e f i r s t m ode of s p a ti a l m a n ip u la tio n .
T h a t i s , th e y
h a v e a s t h e i r o b je c tiv e th e d is p la y of m e d iu m to l a r g e d a ta s e t s f o r s u b s e q u e n t v is u a l s y n th e s is .
T h e y b r in g so m e w h a t l a r g e r d a ta s e t s th a n c a n b e
n o r m a lly v is u a lly a c c o m m o d a te d to a p o in t w h e re h u m a n c h a n n e l c a p a c ity i s
n ot exceeded.
In th i s p r o c e s s , th e y ca n a c c e p t, in f a c t m u s t in c o r p o r a te ,
s o m e in fo r m a tio n l o s s .
T h is ty p e of s y s te m , d e s p ite th e u s e of c o m p u te r s ,
i s c o n s id e r e d to b e c o n c e p tu a lly m a n u a l (v is u a l).
T h e h ig h e r - o r d e r c a te g o r ie s of c u r r e n t s y s te m s a p p ro a c h th e p o in t w h e r e th e
d a ta th e y c u r r e n t ly c o n ta in ca n n o t b e v is u a liz e d e c o n o m ic a lly an d w h e r e th e
s e c o n d m o d e of s p a ti a l m a n ip u la tio n m u s t b e e m p lo y e d .
A t th i s p o in t, b y
r e a s o n of v o lu m e of d a ta (a p ro d u c t of d a ta r e s o lu tio n , s iz e o f d a ta s e t s , a n d
n u m b e r of m a n ip u la tio n s r e q u i r e d ) , it i s l i t e r a l l y im p o s s ib le to c o n c e iv e
m e n ta lly th e r e s u l t .
(T h e p r i m a r y f a c t o r is o n e of h u m a n c h a n n e l c a p a c it y .)
I t i s c o n s id e r e d th a t th e h ig h e r o r d e r of c u r r e n t s y s te m s i s ju s t e n te r in g
t h i s a r e a of c a p a b ility .
S om e s y s t e m s h a v e la r g e d a ta f il e s b u t a r e u n ab le
to m a n ip u la te th e m o th e r th a n to r e t r i e v e s u b s e ts of d a ta e ffic ie n tly .
O th e r
s y s t e m s , h o w e v e r, s u c h a s th e C RA M p r o g r a m o p e r a tin g o n a DIM E f il e , do
a p p ro a c h th i s le v e l of c a p a b ility .
O ne c a n p e r h a p s lo o k fo r w a r d to th e tim e
w h en in s te a d of c a r r y i n g o u t an o p tim iz in g a n a ly s is on a p la n e n e tw o rk in tw o
d im e n s io n s i t w ill b e p o s s ib le to h av e s i m i l a r a n a ly s is of m u ltila y e r n e tw o r k s ,
o r th r e e - d im e n s i o n a l n e tw o rk s th a t g e n e ra lly d e fin e v o lu m e s in s p a c e , o r
d y n a m ic m u ltid im e n s io n a l n e tw o rk s .
In a d d itio n , o r a s an in t e r im s te p , one
m ig h t a n tic ip a te s y s t e m s th a t c a n in c o r p o r a te b o th m o d e ls o f s p a ti a l m a n ip u la tio n on a n in t e r a c t iv e b a s is .
1. S c h m id t, A. 1970.
T h e c u r r e n t s y s t e m s a r e t r u l y in an
2. S c h m id t, A . 1970, T h o m a s , A. 1972.3. S ch m id t, W. 1969.
129
e le m e n ta l s ta t e , b u t g iv e s o m e in d ic a tio n s of th e c a p a b ilitie s th a t ca n b e
e x p e c te d .
T h e fo llo w in g c h a p te r w ill e x a m in e s o m e w h a t m o r e a d v a n c e d s y s te m s th a t
a r e now b e in g d ev e lo p ed .
130
C H A P T E R 5 - C O M P U T E R -A ID E D SYSTEM S U ND ER D E V ELO PM E N T
F O R H ANDLING M A P P E D AND O T H E R LO CA TIO N S P E C IF IC DATA
C o m p u te r - a id e d te c h n iq u e s f o r h a n d lin g m a p p e d a n d o th e r lo c a tio n - s p e c if ic
d a ta a r e d e s c r ib e d h e r e a s b e in g " u n d e r d e v e lo p m e n t" i f th e y h av e n o t b e e n
im p le m e n te d a s d a ta h a n d lin g s y s t e m s in a g e n c ie s o th e r th a n th o s e w h e re
th e te c h n iq u e s w e r e d e v e lo p e d .
T h e y a r e g e n e ra lly r e g a r d e d a s b e in g s t i l l
in th e d e v e lo p m e n t s ta g e b y th e s ta f f c o n c e rn e d w ith t h e i r d e s ig n , an d
u s u a lly a r e n o t d o c u m e n te d to th e le v e l w h e re t r a n s f e r of th e te ch n o lo g y to
o th e r a g e n c ie s co u ld b e e a s i ly a c c o m p lis h e d .
T h is d o e s n o t m e a n th a t
u s e f u l i n t e r i m p ro d u c ts a r e n o t g e n e ra te d b y s u c h s y s t e m s in t h e i r c u r r e n t
s ta t e of d e v e lo p m e n t.
T h e t e r m " u n d e r d e v e lo p m e n t" n e c e s s a r i l y c o v e rs a la r g e an d h e te ro g e n e o u s
r e a l m o f a c tiv ity a n d t h e r e a r e d if f ic u ltie s in p ro v id in g a n in te g r a te d view .
T h e f i r s t h a lf of th i s c h a p te r w ill co n tin u e th e d is c u s s io n of s to r a g e f o r m a t
c a te g o r ie s f r o m C h a p te r 4 , e x a m in in g th e c u r r e n t w o rk o n s y s t e m s w ith
s to r a g e f o r m a ts th a t u s e i r r e g u l a r p o ly g o n s; th e P o ly g o n In fo rm a tio n O v e rla y
S y s te m (P IO S )1 a n d th e C a n a d a G e o g ra p h ic I n f o rm a tio n S y ste m (CGIS)2 w ill
b e ta k e n a s e x a m p le s to i l l u s t r a t e th e c a te g o ry .
T h e s e c o n d h a lf of th e
c h a p te r w ill e x a m in e m o re g e n e ra l c u r r e n t d e v e lo p m e n ts in in p u t (d ig itiz a tio n ),
m a n ip u la tio n , a n d o u tp u t c a p a b ilitie s w h ic h a p p ly to a l l th e c a te g o r ie s of
s y s t e m d is c u s s e d s o f a r .
T h e c h a p te r w ill co n c lu d e w ith a d is c u s s io n o f th e
m o d e rn tr e n d to w a r d m u l ti- f o r m a t s y s t e m s w h ic h co m b in e th e p r o p e r t ie s
o f o th e r s y s t e m s d e s c r i b e d h e r e .
In C h a p te r 6, th e " s t a t e - o f - t h e - a r t
w ill
b e e x a m in e d b y r e f e r e n c e to th e p r o g r e s s r e p r e s e n t e d by a ll of th e d e v e lo p m e n ts d is c u s s e d in C h a p te r s 4 a n d 5.
IR R E G U L A R PO LY G O N CA TEG O R Y O F SYSTEM S
S y s te m s th a t h a n d le r e a l - w o r l d d a ta e le m e n ts w ith i r r e g u l a r p o ly g o n s a s th e ir
p r i m a r y s to r a g e f o r m a t a r e g e n e ra lly c o n s id e r e d to b e s t i l l (1974) u n d e r
d e v e lo p m e n t.
T h e b o u n d a ry c o n d itio n s th a t d is tin g u is h i r r e g u l a r polygo n d a ta s y s te m s f r o m
l o w e r - o r d e r s y s t e m s a r e th a t th e i r r e g u l a r p o ly g o n s m u s t b e s e p a r a te ly
1 . D a n g e rm o n d 1971.
2. T o m lin s o n , R . F . 1967.
131
d e fin e d in th e p r im a r y file s tr u c t u r e , an d th a t th e d a ta r e l a te d to th e m can
b e m a n ip u la te d and e x tr a c te d w ith o u t f u r t h e r p o ly g o n s p e c ific a tio n .
s y s t e m s a r e not n e c e s s a r i ly u n im o d a l.
Such
T h e y m a y in c o r p o r a te in t h e ir
d e s ig n th e a b ility to h a n d le d a ta in f o r m a ts o th e r th a n th e p r im a r y one,
an d to ch a n g e f r o m one fo r m a t to a n o th e r.
I r r e g u l a r poly g o n d a ta s y s t e m s a r e c h a r a c t e r i s t i c a l l y u s e d to s t o r e and
d e s c r i b e th e a r e a l a t tr ib u t e s of a s u r f a c e .
T h e lin e d e fin in g a po ly g o n
b o u n d a ry h a s r e g io n s on e i th e r s id e of it w ith d iff e re n t s u r f a c e a t tr ib u t e s ,
w h e r e a s li n e s d e fin in g p o in t c o n n e c tiv itie s (n e tw o rk s) m a y h a v e th e s a m e
a t tr ib u t e s on e i th e r s id e (th a t i s , th e n e tw o rk m a y p a s s th ro u g h a h o m o geneous are a ).
T h e a t tr ib u t e s of a s u r f a c e c a n b e e x p r e s s e d a s c o n tin u o u s
s in g le - v a lu e d fu n c tio n s , o r a s s te p fu n c tio n s of in d e p e n d e n t c o n tin u o u s
v a r i a b le s .
T h e s e a r e co m m o n ly t r e a t e d a s e i th e r c o n to u r m a p s o r s e ts of
la b e lle d re g io n a l b o u n d a rie s .
In b o th c a s e s , i r r e g u l a r p o ly g o n b o u n d a r ie s
p ro v id e an o p tim a l d a ta r e p r e s e n t a ti o n .
A lth o u g h th e d a ta c o n te n ts of
th e s e tw o ty p e s of i r r e g u l a r poly g o n b o u n d a ry a r e d iff e re n t, an d th e s u b s e q u e n t m a n ip u la tio n p r o c e s s e s c o n s e q u e n tly d if fe r, th e s a m e b a s ic
p r o b le m s of g ra p h ic to n o n -g ra p h ic c o n v e rs io n an d s to r a g e p r e s e n t th e m s e lv e s .
T h e ra n g e of n o n -g ra p h ic c o d e s th a t ca n b e e m p lo y e d to d e s c r ib e i r r e g u l a r
p o ly g o n s w a s g e n e ra lly d is c u s s e d in C h a p te r 4 (pp. 8 7 -9 0 ).
P e r h a p s th e
m o s t c o m m o n f o r m of r e g io n a l co d in g u s e d i s th a t of to p o lo g ic a lly u n r e la te d
n a m e s r e f e r r i n g to a n e x t e r n a l m e tr ic in d e x (ty p ic a lly a m a p ); th e w id ely
u s e d n a m e s of c o u n tr ie s , p r o v in c e s , s t a t e s , c o u n tie s , p a r i s h e s , p r e c in c ts ,
tr a f f i c z o n e s , a d m in is tr a tiv e d i s t r i c t s , a n d c e n s u s s u b d iv is io n s a l l f a l l in to
th e c a te g o r y of n a m e d i r r e g u l a r p o ly g o n s.
T h e n a m e s h a v e v a lu e f o r a l l o -
c a tio n a n d g ro u p in g p u r p o s e s , a r e th e b a s i s of a v a s t am o u n t of s t a t i s t i c a l
l i t e r a t u r e , a n d a r e n o t in th e m s e lv e s m e tr ic a lly defin ed .
T h e r e l a ti v e p o s itio n s of i r r e g u l a r p o ly g o n s c a n , o f c o u r s e , b e d efin e d b y
u s e of a d ja c e n c y c o d e s o r a c o n n e c tiv ity m a tr ix , b u t if a n y h ig h d e g r e e of
a c c u r a c y i s r e q u i r e d in th e g e o g ra p h ic a l lo c a tio n of th e i r r e g u l a r po ly g o n
b o u n d a ry , m e tr ic c o d e s b a s e d on a g e o m e tr ic a l c o o rd in a te s y s t e m m u s t be
e m p lo y e d f o r n o n -g ra p h ic s to r a g e .
132
T h e c o m p le x s h a p e of i r r e g u l a r p o ly g o n s m a k e s th e t a s k of s p a tia l d e fin itio n
g r e a t e r th a n th a t f o r lo w e r o r d e r s of g r a p h ic r e p r e s e n t a ti o n ( r e g u l a r g r id s ,
p o in ts , o r lin e s e g m e n ts ).
An a d d itio n a l im p e tu s to p r e c i s e lin e d e fin itio n
of p o ly g o n s is th a t th e lo c a tio n of th e lin e a lo n g i t s le n g th r e p r e s e n t s a
b o u n d a ry co n d itio n , w h e r e a s lin e s in n e tw o rk s r e p r e s e n t in g flow c o n n e c ti­
v it ie s , f o r e x a m p le , ca n fu lf il t h e i r fu n c tio n w ith l e s s li n e a r p r e c is io n .
T h e v o lu m e of s p a ti a l d a ta n e e d e d to d efin e i r r e g u l a r poly g o n b o u n d a r ie s h a s
c o n s id e r a b le in p a c t on th e e ff o rt n e e d e d to c o n v e rt th e d a ta f r o m g ra p h ic to
n o n - g ra p h ic f o r m a t (w hich w a s th e m a in c o n s tr a in t in c u r r e n t s y s t e m d e s ig n
a n d u s e , a s r e c o g n iz e d in C h a p te r 4 , p. 1 2 6 ).
It a l s o a ff e c ts th e s to r a g e
a n d m a n ip u la tio n of th e d a ta , an d th e ch o ic e of f il e s t r u c t u r e s .
T h e r e l a ti o n s h i p b e tw e e n th e v o lu m e of s to r a g e d a ta an d th e c h o ic e an d
r e s o lu t io n (fid e lity ) of th e v a r io u s s to r a g e f o r m a ts i s il l u s t r a t e d in th e
fo llo w in g s e r i e s of d ia g r a m s (pp. 133-135).
F ig . 5. 1 i s a s a m p le m a p (g ra p h ic im a g e only) m a d e up o f a n a r b i t r a r y s e t
of li n e s w ith in a 1 0 -s q . in . r e c ta n g le .
W ith d iff e re n t s e t s o f d e s c r i p to r d a ta
r e l a t e d to s u c h a m a p , th e lin e s c o u ld c o n c e iv a b ly r e p r e s e n t a n e tw o rk
(s u c h a s a h ig h w ay n etw o rk ) o r a s e t of 15 b o u n d ed r e g io n s (s u c h a s a p r e s e n t
la n d u s e m a p ).
T h e r e a r e a p p ro x im a te ly 33 in . of lin e le n g th in th e to ta l
s e t of i n t e r i o r a n d e x t e r io r b o u n d a rie s .
In c o m p a r is o n w ith r e a l - w o r l d
m a p s of s i m i l a r s u b je c ts , th e s a m p le m a p m ig h t s u b je c tiv e ly b e d e s c r ib e d
to b e of " m e d iu m " d a ta d e n s ity .
F ig . 5. 2 sh o w s th e r e s u l t of r e g a r d in g th e s a m p le m a p a s a s e t of i r r e g u l a r
p o ly g o n s an d u s in g th e p o in t d a ta s to r a g e f o r m a t to r e c o r d t h e i r c e n tr o id
c o o r d in a te s .
A p p ro x im a te ly 15 d a ta p o in ts w o u ld n e e d to b e c o d e d if th is
a p p ro a c h w e r e u s e d .
F ig . 5. 2. 1 sh o w s th e s iz e o f a s q u a r e g r id th a t w o u ld
r e s u l t if 15 a r b i t r a r y r e g u l a r a r e a c e lls w e r e u s e d to d e s c r ib e th e s a m e a r e a .
In F ig . 5. 3, th e s a m p le m a p is ta k e n to b e a n e tw o rk w h e r e th e flow b e tw e e n
i n t e r s e c ti o n s is o f c o n c e rn and w h e re it c a n b e a d e q u a te ly r e p r e s e n t e d b y
s t r a i g h t - l i n e s e g m e n ts b e tw e e n i n t e r s e c ti o n s .
(An in t e r s e c ti o n o c c u rs
w h e re t h r e e o r m o re lin e s e g m e n ts m e e t; m a p c o r n e r p o in ts a r e a s p e c i a l
c a s e . ) S uch a lin e s e g m e n t m a p c o u ld b e s a t i s f a c t o r i l y e n c o d ed w ith 32 d a ta
F ig . 5. 2. C en troid co o rd in a tes
(15 data p o in ts).
F ig . 5. 1. Sam ple m ap of 15 ir r e g u la r p olygon s.
133
F ig . 5. 2. 1. F ifte e n a rb itr a ry r e g u la r -a r e a c e lls .
F ig . 5. 3. N e tw o rk r e p r e s e n t a ti o n (32 d a ta p o in ts).
F ig . 5. 4. 1. N in e ty -e ig h t a r b i t r a r y r e g u l a r - a r e a
c e lls .
134
F ig . 5 .3 .1 . T h ir ty - tw o a r b i t r a r y r e g u l a r - a r e a
c e lls .
F ig . 5 .4 . C o a r s e p o ly g o n r e p r e s e n t a ti o n
(98 d a ta p o in ts .
F ig . 5. 5. F in e p o ly g o n r e p r e s e n t a ti o n : 10 p o in ts
p e r in . (330 d a ta p o in ts).
F ig . 5. 6. 1. O ne th o u s a n d , s ix h u n d re d an d fifty
a r b i t r a r y r e g u l a r - a r e a c e lls .
135
F ig . 5. 5. 1. T h r e e h u n d re d an d t h i r t y a r b i t r a r y
r e g u l a r - a r e a c e lls .
F ig . 5. 6. F in e p o ly g o n r e p r e s e n t a ti o n : 50 p o in ts
p e r in . (1 , 650 d a ta p o in ts ).
136
p o in ts .
F ig . 5. 3. 1 sh o w s th e s iz e of s q u a r e g r id th a t w o u ld r e s u l t i f 32
a r b i t r a r y r e g u l a r - a r e a c e lls w e r e u s e d to d e s c r i b e th e s a m e a r e a .
In F ig . 5. 4 , th e s a m p le m a p is r e g a r d e d a s a s e t of i r r e g u l a r p o ly g o n s
w h o se b o u n d a r ie s m u s t b e d efin ed .
A c c o rd in g ly , th e b o u n d a r ie s a r e
r e p r e s e n t e d , in c o a r s e a p p ro x im a tio n , by s tr a i g h t- li n e s e g m e n ts b e tw e e n
n o d e s (c o o rd in a te p o in ts) th a t h a v e b e e n m a n u a lly s e le c te d b e tw e e n i n t e r s e c tio n s .
T h is i s p ro b a b ly th e lo w e s t le v e l of f id e lity (an d h e n c e d a ta vo lu m e)
th a t w o u ld b e a c c e p ta b le to a u s e r in t e r e s te d in th e lo c a tio n of th e b o u n d a r ie s .
N in e ty - e ig h t d a ta p o in ts a r e u s e d to en c o d e th e b o u n d a rie s in th i s m a n n e r.
F ig . 5. 4 . 1 sh o w s th e s iz e of g r id s q u a r e th a t w o u ld r e s u l t if 98 a r b i t r a r y
r e g u l a r - a r e a c e lls w e r e u s e d to d e s c r ib e th e s a m e a r e a .
F ig s . 5. 5 a n d 5. 6 a r e to p o lo g ic a lly th e s a m e a s F ig . 5. 4 ; th e d if f e re n c e l i e s
o n ly in th e s p a c in g of th e c o o rd in a te p o in ts u s e d to d e s c r i b e th e c o n fig u ra tio n
of th e b o u n d a r ie s .
In p r a c t ic e , th e s to r a g e f o r m a ts il l u s t r a t e d in F ig s . 5. 5
a n d 5. 6 r e s u l t f r o m th e u s e of v a r io u s ty p e s o f s e m i- a u to m a tic d ig itiz a tio n
te c h n iq u e s w h ic h p ro d u c e a s t r e a m of c o o rd in a te p o in ts b y fo llo w in g o r
s c a n n in g th e li n e s on th e s o u r c e m a p .
tiv e a n d c a n b e v a r i e d w ith in one m a p .
T h e s p a c in g of th e p o in ts i s s u b je c H o w e v e r, 10 p o in ts p e r in . i s u s u a lly
c o n s id e r e d to b e th e w id e s t s p a c in g a t w h ic h th e c o n fig u ra tio n of i r r e g u l a r
li n e s c a n b e f in e ly a p p ro x im a te d .
A s p a c in g of 50 p o in ts p e r in . is co m m o n ;
i t a llo w s p o ly g o n s to b e d e fin e d w ith m in im a l l o s s of a r e a l a c c u r a c y , b u t
w ith li n e s th a t do n o t a p p e a r "s m o o th " to n o r m a l v is u a l in s p e c tio n .
A
s p a c in g of 100 p o in ts p e r in . p ro d u c e s p o in ts th a t a r e w ith in th e w id th of
th e o r ig i n a l lin e o n th e m a p , an d th i s m u s t b e c o n s id e r e d to b e th e m a x im u m
n e e d e d f o r a c c u r a te r e p r e s e n t a ti o n of th e li n e s .
S uch a s p a c in g m ig h t b e
c o n s id e r e d n e c e s s a r y f o r c a rto g r a p h ic p u r p o s e s , w h e r e th e lo c a tio n a l
a c c u r a c y of c lo s e ly s p a c e d lin e s d e p ic tin g c o n to u rs (fo r ex a m p le) m u s t b e
p re se rv e d .
G iv en th a t t h e r e a r e 33 in . of lin e on th e s a m p le m a p , i t w o u ld
b e n e c e s s a r y to e n c o d e 330,
s p a c in g s m e n tio n e d ab o v e .
1 ,6 5 0 , a n d 3 ,3 0 0 p o in ts r e s p e c t iv e l y f o r th e
F ig . 5. 5 i l l u s t r a t e s a fin e po ly g o n r e p r e s e n t a ti o n
u s in g 10 p o in ts p e r in . (330 to t a l p o in ts), a n d F ig . 5. 5. 1 sh o w s th e s iz e of
g r id s q u a r e th a t w o u ld r e s u l t if 330 a r b i t r a r y r e g u l a r - a r e a c e lls w e r e u s e d
to d e s c r i b e th e s a m e a r e a .
F ig . 5. 6 i l l u s t r a t e s a f in e po ly g o n r e p r e s e n t a ti o n
137
u s in g 50 p o in ts p e r in . (1, 650 p o in ts in to ta l) , a n d F ig . 5. 6. 1 sh o w s th e
s iz e of 1, 650 g r id s q u a r e s to d e s c r i b e th e s a m e a r e a .
E a c h of th e a p p ro a c h e s to d a ta s to r a g e d e s c r ib e d a b o v e h a s a d v a n ta g e s an d
d is a d v a n ta g e s f o r d a ta r e p r e s e n t a ti o n an d s u b se q u e n t d a ta m a n ip u la tio n .
It
i s im p o r ta n t to n o te th a t a s tr o n g r e la tio n s h ip e x i s t s b e tw e e n th e s to r a g e
f o r m a t c h o s e n a n d th e v o lu m e of d a ta g e n e ra te d .
M e tr ic d e fin itio n of
i r r e g u l a r p o ly g o n b o u n d a rie s in c u r s th e e x p e n s e o f s to r in g s ig n ific a n tly
h ig h e r v o lu m e s of d a ta th a n s to r a g e f o r m a ts th a t do n o t a tte m p t to r e p r e s e n t
th e p o ly g o n b o u n d a ry a c c u r a te ly .
T h is i s in tu itiv e ly s e lf- e v id e n t, b u t th e
d e g re e of i n c r e a s e in d a ta v o lu m e b e tw e e n f o r m a ts i s in s tr u c tiv e .
At a
" c o a r s e " le v e l of i r r e g u l a r poly g o n d e fin itio n (F ig . 5. 4 ), th e v o lu m e of
d a ta r e q u i r e d i s 3 to 6 t i m e s g r e a t e r th a n l o w e r - o r d e r f o r m a ts .
A t a " fin e "
l e v e l of i r r e g u l a r p o ly g o n d e fin itio n (F ig s . 5. 5 a n d 5. 6), th e v o lu m e of d a ta
r e q u i r e d i s 10 to 200 t i m e s g r e a t e r .
T h e fo llo w in g s e r i e s of d ia g r a m s (pp. 138-39) p r o v id e s a g e n e r a l c o m p a ris o n
b e tw e e n s to r a g e f o r m a ts u s in g i r r e g u l a r p o ly g o n s a n d th o s e u s in g a r b i t r a r y
re g u la r a re a s .
T h e v o lu m e o f d a ta a n d th e c o m p a ra tiv e r e s o lu tio n of th e
tw o s to r a g e f o r m a ts a r e of c o n c e rn , w h e r e b o u n d a ry d e fin itio n a tte m p ts to
b e e x p lic it.
T h e f i r s t f ig u r e (F ig . 5. 7) is . s im p ly th e s a m p le m ap f r o m th e p re v io u s s e r i e s ,
w ith a s in g le i r r e g u l a r poly g o n in d ic a te d .
T h e n e x t fiv e il lu s tr a t io n s ( F ig s .
5. 7. 1 - 5. 7. 5) show th e b o u n d a ry of th e s a m e p o ly g o n a s i t w o u ld b e s to r e d
i f a s s ig n e d to a r e g u l a r a r b i t r a r y g r id in c u r r in g p r o g r e s s iv e l y l a r g e r
v o lu m e s of d a ta s to r a g e .
(T he v a lu e of th e i r r e g u l a r poly g o n is a s s ig n e d
t o a r e g u l a r g r id u n it if m o re th a n 50% of th e r e g u l a r g r id f a lls w ith in th e
i r r e g u l a r p o ly g o n .)
In e a c h c a s e , th e a r b i t r a r y g r id s iz e c h o s e n u s e s th e s a m e v o lu m e of
s to r a g e a s th e a l te r n a t iv e s to r a g e f o r m a t on w h ic h it i s s u p e rim p o s e d .
It
c a n b e s e e n th a t th e s to r a g e of i r r e g u l a r p o ly g o n s in a r b i t r a r y g r id f o r m a t
e i th e r g iv e s a n u n r e a l f o r m to th e r e a l - w o r l d d a ta e le m e n t o r im p o s e s a
h ig h e r b u r d e n of d a ta v o lu m e to o b ta in c o m p a r a b le fid e lity .
It m u s t b e
e m p h a s iz e d th a t th i s p a r t ic u l a r s e r i e s of e x a m p le s il l u s t r a t e s th e e ffe c t
138
F ig . 5. 7.
S am p le m ap w ith s in g le
i r r e g u l a r p o ly g o n in d ic a te d .
F ig . 5. 7. 1.
P o ly g o n b o u n d a ry a s s ig n e d
to r e g u l a r g r id u s in g s a m e
d a ta vo lu m e (15 d a ta p o in ts)
a s c e n tr o id c o o rd in a te s .
F ig . 5. 7. 2.
P o ly g o n b o u n d a ry a s s ig n e d
to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (32 d a ta p o in ts )
a s lin e n etw o rk .
139
F ig . 5 . 7 . 3 .
P o ly g o n b o u n d a ry a s s ig n e d
to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (98 d a ta p o in ts )
a s c o a r s e p o lygon.
F ig . 5 . 7 . 4 .
P o ly g o n b o u n d a ry a s s ig n e d
to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (330 d a ta p o in ts )
a s fin e p o ly g o n s a t 10 p o in ts
p e r in .
F ig . 5 . 7 . 5 .
P o ly g o n b o u n d a ry a s s ig n e d
to r e g u l a r g r id u s in g s a m e
d a ta v o lu m e (1, 650 d a ta
po in ts) a s fin e p o ly g o n s
a t 50 p o in ts p e r in .
140
o n ly o n o n e s p e c if ic p o ly g o n .
T h e e r r o r in h e re n t in th e tr a n s f o r m a tio n
b e tw e e n s to r a g e f o r m a ts m a y b e l e s s s e v e r e if th e s h a p e o f th e i r r e g u l a r
p o ly g o n i s c l o s e r to th a t of th e a r b i t r a r y a r e a u s e d , an d w ill p ro b a b ly b e
m o r e s e v e r e if th e i r r e g u l a r p o ly g o n h a s a m o re co m p lex c o n fig u ra tio n .
No
m e a s u r e s of th e d e g r e e of a r e a l c o r r e l a ti o n ca n b e v a lid ly o b ta in e d f r o m th i s
s in g le e x a m p le .
T h e p o ly g o n u s e d f o r c o m p a ris o n , h o w e v e r, i s h o t a
c o m p le x i r r e g u l a r p o ly g o n , a n d th e g e n e ra l tr e n d il lu s tr a t e d is p ro b a b ly
v a lid .
G iv en r e a l - w o r l d d a ta e le m e n ts in th e f o r m o f i r r e g u l a r p o ly g o n s ,
a h ig h v o lu m e of d a ta i s n e e d e d to d efin e t h e i r b o u n d a r ie s m e tr ic a lly , b u t
o th e r ty p e s o f s to r a g e f o r m a t p ro v id e r e p r e s e n t a ti o n a t a lo w e r r e s o lu t io n
e v e n w ith e q u iv a le n t v o lu m e s of m e tr ic d a ta .
In c o n s e q u e n c e , o n ly a r e l a ti v e ly n a rro w r a n g e of n o n -g ra p h ic c o d e s c a n
b e u s e d to d e fin e th e lo c a tio n of th e b o u n d a ry of an i r r e g u l a r p o ly g o n
m e tr ic a lly w ith o u t l o s s of r e s o lu t io n o r p ro h ib itiv e ly ex p e n siv e (g r id s q u a re )
v o lu m e s of d a ta .
W ith in th e r a n g e , th r e e a p p ro a c h e s c a n b e r e c o g n iz e d .
T h e f i r s t a p p ro a c h , a n d th e m o s t co m m o n , i s th e o n e u s e d in th e e x a m p le s
a b o v e , w h ic h c a n b e r e f e r r e d to a s " c h a in en c o d in g ".
C o o rd in a te p o in ts a t
c h o s e n s p a c in g s a r e r e c o r d e d e i th e r m a n u a lly o r b y m a c h in e to d e fin e th e
b o u n d a ry , w ith s tr a i g h t- li n e s e g m e n ts a s s u m e d to jo in th e p o in ts .1
A
v a r i a ti o n on th e s a m e th e m e is to d e fin e b o u n d a ry p o in ts (u s u a lly i n t e r s e c tio n s ) a n d d e s c r i b e th e p o in t lo c u s b e tw e e n in t e r s e c ti o n s b y a s e r i e s o f
d ir e c tio n a n d d is ta n c e c o d e s , w ith o u t a c tu a lly r e c o r d in g th e c o o rd in a te
v a lu e s of th e i n t e r s t i t i a l p o in ts .
T h e a p p ro a c h u s in g c o o rd in a te p o in t r e c o r d s
i s th e one e m p lo y e d in th e m a jo r it y of i r r e g u l a r polygon s y s te m s a n d w ill b e
d e s c r i b e d m o r e fu lly i n th e s y s t e m d e s c r ip tio n s g iv e n belo w .
T h e s e c o n d a p p ro a c h , a n d p e r h a p s th e m o s t m a th e m a tic a lly e le g a n t, i s to
a p p ro x im a te th e b o u n d a r y lin e p ie c e b y p ie c e w ith a n a ly tic a lly s im p le c u r v e s ,
a s i s done in SK E T C H PA D an d i t s s u c c e s s o r s . 2 T h is a p p ro a c h c a n g r e a t l y
r e d u c e th e v o lu m e of d a ta n e e d e d to d efin e a poly g o n b o u n d a ry m e tr ic a lly ,
a t th e e x p e n s e , h o w e v e r , of s o m e s u b se q u e n t c o m p le x ity in d a ta m a n ip u la tio n .
T h e a p p ro a c h i s m e n tio n e d f o r th e s a k e of c o m p le te n e s s , b u t h a s n o t
b e e n a d o p te d b y an y i r r e g u l a r p o ly g o n s y s t e m now u n d e r d e v e lo p m e n t.
1. F r e e m a n 1961, F r e e m a n an d G a r d n e r 1964.
2. S u th e rla n d 1963.
141
T h e t h i r d a p p ro a c h i s th e r e p r e s e n t a ti o n of p la n a r re g io n s b y t h e i r
" s k e le to n s " .
If th e s k e le to n s , a s d e fin e d b y a p a r c e l of g r id s q u a r e s , of
a d ja c e n t p la n e r e g i o n s a r e m e tr ic a lly d e s c r ib e d in s u ff ic ie n t d e ta il, th e
b o u n d a ry b e tw e e n th e m i s th e r e b y m e tr ic a lly d efined.
S e v e r a l ty p e s of s k e le to n r e p r e s e n t a ti o n ca n b e e n v isa g e d ; th e o ne u s e d b y
P f a lt z a n d R o s e n fe ld 1 a s s u m e s a r e c t a n g u la r m a tr ix of p o in ts o v e r l a id on
th e a r e a c o n ta in in g th e re g io n .
W ith in th e m a tr ix , " n e ig h b o u rh o o d s" c a n
b e d e fin e d b y a p o in t a n d a r a d iu s .
N eig h b o u rh o o d
F ig . 5. 8.
M a x im a l n e ig h b o u rh o o d of a p o in t in a m a tr ix .
In F ig . 5. 8 a b o v e , th e n eig h b o u rh o o d is d e fin e d b y th e lo c a tio n o f p o in t P
w ith a r a d i u s of 2.
A n e ig h b o u rh o o d i s te r m e d a " m a x im a l n e ig h b o u rh o o d "
if it i s n o t p r o p e r l y c o n ta in e d in an y o th e r s u c h n eig h b o u rh o o d .
An ir r e g u la r
p o ly g o n c a n b e r e g a r d e d a s a u n io n of m a x im a l n e ig h b o u rh o o d s, a n d th u s
c a n b e s p e c if ie d b y c e n t r e s an d r a d i i of th o s e n eig h b o u rh o o d s.
F ig . 5. 9 .
R e p r e s e n ta tio n of an i r r e g u l a r poly g o n b y m a x im a l
n e ig h b o u rh o o d s.
T h e i r r e g u l a r p o ly g o n in F ig . 5. 9 i s d efin ed b y th e m a x im a l n eig h b o u rh o o d s
of p o in ts A , B , C , D w ith r a d i i 3, 2, 1, a n d 0 .
P f a lt z a n d R o s e n fe ld c o m p a r e d th e v o lu m e of d a ta g e n e ra te d b y th i s a p p ro a c h
w ith th a t of c h a in - e n c o d in g i r r e g u l a r p o ly g o n s, an d c a m e to th e c o n c lu s io n
1 . P f a l t z a n d R o s e n fe ld 1967.
142
th a t f o r th e s a m e re s o lu tio n of b o u n d a ry d e fin itio n a p p ro x im a te ly th e s a m e
n u m b e r of d a ta p o in ts m u s t b e en c o d ed .
S p e c ific a lly , f o r a s e r i e s o f
i r r e g u l a r p o ly g o n s (c o u n try b o r d e r s ) , th e r e s u l t s g iv e n in T a b le 5. 1
w e r e o b ta in e d .
A
B
C
D
E
B o u n d a ry p o in ts
338
178
231
286
440
197
262
S k e le to n p o in ts
371
135
407
272
402
183
244
I r r e g u l a r polygon
T a b le 5. 1.
G
F
N u m b e r of d a ta p o in ts r e q u ir e d to d efin e a s e r i e s o f i r r e g u l a r
p o ly g o n s b y c h a in -e n c o d in g bo u n d a rie s a n d b y s k e le to n m eth o d .
I t i s p o s s i b le to g e n e ra te a c h a in -e n c o d e d r e p r e s e n t a ti o n of a b o u n d a ry ,
g iv e n th e s k e le to n p o in ts , an d it is m o re e ffic ie n t to c a r r y o u t s o m e ty p e s
of s e t - t h e o r y o p e ra tio n s u s in g s u c h e n c o d in g s .
In p a r t i c u l a r , th e m e th o d
p ro v id e s a v e r y e ff ic ie n t f o r m of s to r a g e if it i s n e c e s s a r y to d e te r m in e
w h e th e r p o in ts li e w ith in o r o u ts id e r e g io n s .
T h e a p p ro a c h a ls o s e e m s
a m e n a b le to h i e r a r c h i c a l co d in g of d e s c r i p to r d a ta , a n d w o u ld p r o v id e
e c o n o m ie s in s o m e f o r m s of g e n e r a liz a tio n a n d r e t r i e v a l o f d e s c r i p to r
d a ta .
U n fo rtu n a te ly , th e a p p ro a c h h a s n o t b e e n a d o p te d b y an y a g e n c y f o r
a n i r r e g u l a r p o ly g o n d a ta h a n d lin g s y s t e m u n d e r d e v e lo p m e n t a t th i s t i m e .
T h e d e fin itio n of i r r e g u l a r poly g o n d a ta s y s te m s u s e d a t th e b e g in n in g o f
t h i s c h a p te r w a s th a t th e i r r e g u l a r p o ly g o n s th e m s e lv e s m u s t b e d e fin e d
in th e p r i m a r y f il e s t r u c t u r e of th e s y s t e m s c o n c e rn e d .
It can be seen
f r o m th i s d is c u s s io n of m e tr ic d e fin itio n s th a t p o ly g o n b o u n d a r ie s a r e
g e n e ra lly d e fin e d w ith r e f e r e n c e to s o m e s t r u c t u r e of c o o r d in a te p o in ts .
In
a d d itio n t o c a r r y i n g th e r e q u i r e d v o lu m e of d a ta , if p o ly g o n f o r m s a r e t o b e
id e n tifie d th e f ile s t r u c t u r e m u s t o b v io u s ly in c lu d e c o d in g o f th e r e l a t i o n s h ip s b e tw e e n th e e le m e n ts of th e poly g o n fo r m ; b e tw e e n p o in ts th a t f o r m
lin e s e g m e n ts ; a n d b e tw e e n lin e s e g m e n ts th a t f o r m p o ly g o n s.
m u s t b e e x p lic itly o r im p lic itly id e n tifie d .
T h is " c h a in
S im ila rly , if m o r e th a n o n e
p o ly g o n i s c o n c e rn e d , th e r e la tio n s h ip b e tw e e n p o ly g o n s m u s t b e c o d e d to
p ro d u c e m a p s .
T h is c a n b e im p lic it in m e t r i c c o d in g , b u t a d v a n ta g e s m a y b e
g a in e d f r o m s p e c ify in g th e r e la tio n s h ip s b e tw e e n p o ly g o n s m o r e d ir e c tl y .
In
143
a d d itio n , th e d e s c r i p t o r d a t a (w hich m a y b e v e r y com plex ) h a s to b e r e l a te d
to a p p r o p r ia te p o ly g o n b o u n d a rie s a t a n e f fic ie n t le v e l in th e h ie r a r c h y of
r e la tio n s h ip s b e tw e e n c o d e d im a g e e le m e n ts .
F o r e x a m p le , i f m an y
c o o rd in a te p o in ts a r e u s e d to d e fin e a poly g o n b o u n d a ry , it m a y b e p r o h ib itiv e ly e x p e n s iv e in t e r m s of d a ta v o lu m e a n d p r o c e s s in g c o s t to a tta c h th e
d e s c r ip tio n of th e p o ly g o n c o n te n t to e a c h p o in t; w h e r e a s in a p o in t d a ta
s y s t e m th i s i s a n o r m a l p r o c e d u r e .
C le a r ly , i r r e g u l a r po ly g o n d a ta s y s te m s
d e m a n d m o re s o p h is tic a te d d a ta s t r u c t u r e s th a n l o w e r - o r d e r s y s te m s .
E x a m p le s of th e d a ta s t r u c t u r e s e m p lo y e d in s y s t e m s u n d e r d ev e lo p m en t
a r e g iv e n b elo w .
S y s te m s u s in g th e i r r e g u l a r p o ly g o n a p p ro a c h c o m m o n ly u s e a tr a c in g ty p e
of d ig i tiz e r , a n a u to m a tic lin e -f o llo w in g d e v ic e , o r s o m e f o r m o f e l e c t r o o p tic a l s c a n n e r to p ro d u c e th e c o d e d m e t r i c r e p r e s e n t a ti o n o f th e g ra p h ic
s o u r c e d a ta .
A l a r g e - s c a l e c o m p u te r i s m o s t o fte n u s e d to s t o r e an d m a n i-
p u la te th e d a ta , b u t r e c e n t d e v e lo p m e n ts in m in i- c o m p u te r s h a v e a llo w ed
th e m to b e u s e d f o r c r e a tin g an d a c c e s s i n g la r g e o ff-lin e d a ta s t o r e s .
D ata
m a n ip u la tio n c a p a b ili tie s a ffe c te d b y th e f o r m a t in c lu d e th e a b ility to m e a s u r e
a r e a s an d p e r i m e t e r le n g th s , a n d to g ro u p d a ta in s e t s o f p o ly g o n s e ith e r
know n to th e s y s t e m o r a r b i t r a r i l y g e n e ra te d b y th e s y s te m .
P e r h a p s th e
m o s t u s e f u l c a p a b ility is th a t of o v e rla y in g o n e s e t of i r r e g u l a r p o ly g o n s
o n a n o th e r , to d e te r m in e th e c h a r a c t e r i s t i c s of c o m p o site s u r f a c e s .
P o ly g o n d a ta s y s t e m s h a v e b e e n a d o p te d f o r h a n d lin g s u r f a c e - d e s c r ip ti v e
d a ta s e t s f r o m r e l a t i v e l y l a r g e a r e a s ; th e s y s te m s h av e c o m m o n ly b e e n
d e v e lo p e d to h a n d le r e g i o n a l d a ta .
D a ta r e t r ie v e d f r o m su c h s y s t e m s a r e
ty p ic a lly d is p la y e d on a lin e p lo t te r o r in ta b u la r f o r m on a lin e p r in t e r ,
a lth o u g h th e u s e of c a th o d e r a y tu b e s (both s to r a g e tu b e an d r e f r e s h e d
disp la y ) i s b e c o m in g m o r e p re v a le n t.
T Y P E S O F IR R E G U L A R PO L Y G O N SYSTEM S
I r r e g u l a r p o ly g o n d a ta s y s t e m s co m m o n ly u s e c h a in -e n c o d in g to d efin e th e
polygon b o u n d a r ie s .
F o r c o n v e n ie n c e of d e s c r ip tio n , tw o ty p e s o f c h a in -
en c o d in g c a n b e r e c o g n iz e d .
T h e d if fe re n c e b e tw e e n th e tw o ty p e s i s r e l a te d
s o le ly to th e p r a c t i c e of e n c o d in g a n d u tility of th e su b se q u e n t r e c o r d s , a s
th e a p p r o a c h e s a r e to p o lo g ic a lly id e n tic a l.
T h e f i r s t r e l i e s o n th e
144
a p p ro x im a tio n of p o ly g o n b o u n d a rie s b y s tr a i g h t lin e s e g m e n ts b e tw e e n
n o d e s v is u a lly c h o s e n b y a n o b s e r v e r .
A n e x a m p le of th i s a p p ro a c h is
show n in F ig . 5 .4 ab o v e ; it r e s u l t s in r e c o r d s th a t w ill b e te r m e d " c o a r s e "
p o ly g o n s.
T h e s e c o n d r e l i e s on th e d e fin itio n of th e poly g o n b o u n d a r ie s b y
a s t r e a m of p o in ts (b etw ee n w h ich s tr a i g h t lin e s e g m e n ts a r e a s s u m e d ),
u s u a lly g e n e ra te d b y a s e m i - a u to m a tic o r a u to m a tic d e v ic e .
T h is a p p ro a c h
( F ig s . 5. 5 an d 5. 6 above) r e s u l t s in r e c o r d s th a t w ill b e te r m e d " fin e "
p o ly g o n s.
T h is is an e n t ir e l y a r b i t r a r y d is tin c tio n an d on e o f o n ly te m p o r a r y
m e r it, a s new en c o d in g m e th o d s a r e b e in g d e v e lo p e d b y w h ich i r r e g u l a r p o ly g o n s w ill b e d e fin e d b y m e t r i c c o d e s a t v a r io u s p o in ts on th e c o n tin u u m
b e tw e e n " c o a r s e " an d " fin e " .
T h e c a te g o r ie s d o , h o w e v e r, r e f l e c t tw o m a in
a p p ro a c h e s to th e d e s ig n of i r r e g u l a r p o ly g o n d a ta s y s t e m s w h ic h h a v e b e e n
a tte m p te d in th e p a s t d e c a d e an d a r e e m p lo y e d b y s y s t e m s now u n d e r d e v e lo p m e n t.
S e v e r a l s y s te m s f o r h a n d lin g i r r e g u l a r p o ly g o n s in b o th o f th e
a b o v e c a te g o r ie s e x is t to s t o r e a n d m a n ip u la te c o n to u r d a ta ; h o w e v e r, th e
e x a m p le s d e s c r ib e d b elow w ill b e d ra w n f r o m s y s t e m s th a t u s e i r r e g u l a r
p o ly g o n s to d efin e r e g i o n s , a s th e p r o b le m s a r e of c o m p a r a b le c o m p le x ity
a n d th e re g io n a l s y s t e m s r e l a t e m o r e d ir e c tl y to th e a u t h o r 's w o rk w ith th e
C a n a d a G e o g ra p h ic In fo rm a tio n S y s te m ( d e s c r ib e d in th e A ppendix).
C o a r s e P o ly g o n S y s te m s : th e E x a m p le of P IO S
S e v e r a l s y s t e m s h a v e b e e n d e s ig n e d w ith c o a r s e p o ly g o n s a s a p r im a r y d a ta
s to r a g e f o r m a t.
C o lu m b ia
T y p ic a l e x a m p le s a r e M A P /M O D E L 1 (M ap M o d el S y ste m ,
R e g io n A s s o c ia tio n of G o v e rn m e n ts , P o r tla n d , O reg o n ), P IO S 2
(P o ly g o n In fo rm a tio n O v e rla y S y ste m , C o m p re h e n s iv e P la n n in g O rg a n iz a tio n ,
S an D iego C ounty, C a lifo r n ia ), a n d N R IS3 (N a tu ra l R e s o u r c e s In fo rm a tio n
S y ste m , B o ein g C o m p u te r S e r v ic e s , I n c .) .
A ll th e s y s t e m s e x h ib it s i m i l a r
b a s ic c h a r a c t e r i s t i c s an d c lo s e ly fo llo w th e c o n c e p ts th a t o r ig in a te d in th e
M A P /M O D E L s y s t e m b e tw e e n 1964 a n d 1968.
D e s p ite th e le n g th of tim e
o v e r w h ic h th e s y s t e m s h a v e b e e n d e v e lo p e d , r e c e n t c o m m u n ic a tio n w ith
th o s e re s p o n s ib le f o r t h e i r d e v e lo p m e n t c o n f ir m s th a t th e a p p ro a c h i s s t i l l
e x p e rim e n ta l.
N one of th e s y s t e m s i s in ro u tin e o p e r a tio n in a n a g e n c y th a t
i s u s in g , r a t h e r th a n d e v e lo p in g , th e a p p ro a c h .
T h e P IO S s y s t e m is b r ie f ly
d e s c r ib e d b elo w .
1. A r m s 1 9 6 7 , 1 9 6 8 , 1 9 6 9 , 1 9 7 0 . 2 . D a n g e r m o n d 1 9 7 1 , C o m p r e h e n s i v e
P la n n in g O r g a n iz a tio n 1971. 3. B o e in g 1 9 7 2 a, 1972b.
145
L ik e M A P /M O D E L a n d N R IS, P IO S is b a s e d on th e c o n c ep t th a t th e g ra p h ic
c o n te n t of a m a p i s m a d e up of i r r e g u l a r s tr a i g h t- s id e d p o ly g o n s th a t d e fin e
h o m o g e n eo u s a r e a s .
P o in ts , an d lin e s e g m e n ts th a t do not b o u n d p o ly g o n s,
a r e c o n s id e r e d to b e s p e c i a l c a s e s of p olygons.
T h e p u rp o s e of im p le m e n tin g P IO S in San D iego C ounty, C a lif o r n ia , is
p r im a r il y to s u m m a r iz e s o il d a ta b y tr a f f i c zone f o r u s e in a n u r b a n d e v e lo p m e n t m o d e l.
T h e s e c o n d a r y o b je c tiv e i s to p ro v id e a c a p a b ility to a g g r e g a te
th e s o il d a ta in to o th e r a r e a l u n its e c o n o m ic a lly f o r su b se q u e n t a p p lic a tio n s .
T w o s e t s of m a p s h a v e b e e n s p e c ia lly p r e p a r e d f o r th e p r o je c t.
A ll m a p s
a r e d ra w n on s ta b le b a s e m a t e r i a l (m y la r) a t a s c a le of 1 :2 4 ,0 0 0 w ith an
a p p r o x im a te s h e e t s iz e of 40 in . x 45 in . T h e s ta t e p la n e c o o rd in a te s o f a t
l e a s t t h r e e r e f e r e n c e p o in ts (ed g e " tic k " m a rk s ) a r e g iv e n o n e a c h s h e e t,
a n d e a c h s h e e t i s u n iq u e ly n u m b e re d w ith in i t s s e t.
T h e f i r s t s e t of
a p p r o x im a te ly 15 s h e e t s (s o m e p a r t i a l s h e e ts ) sh o w s s o i l d a ta b o u n d a r ie s
( ir r e g u l a r p o ly g o n s ). E a c h s h e e t i s o v e r la id on a s e p a r a t e id e n tic a l co p y
(b lu e p rin t) on w h ic h a r e w r itt e n th e s o il- ty p e s y m b o ls .
m a p s e t C ontains a p p r o x im a te ly 3 0 ,0 0 0 p o ly g o n s.
T h e to t a l s o il d a ta
T h e n u m b e r o f p o ly g o n s
o n e a c h s h e e t v a r i e s w id e ly , b u t s u b je c tiv e ly ca n b e c o n s id e r e d to b e of
m e d iu m to low d e n s ity (a r a n g e of 500 to 5 ,0 0 0 poly g o n s p e r s h e e t).
The
s e c o n d s e t of m a p s a r e o v e r la y s f o r th e f i r s t s e t an d show tr a f f i c zo n e
b o u n d a r ie s ( ir r e g u l a r p o ly g o n s); th e to t a l of s u c h p o ly g o n s in th e m a p s e t i s
a p p ro x im a te ly 250.
A g a in , th e n u m b e r of poly g o n s o n e a c h s h e e t v a r i e s
w id e ly , b u t a l l c a n b e c o n s id e r e d to c o n ta in lo w - d e n s ity d a ta .
zo n e n u m b e r i s w r itt e n d ir e c tl y on th e o v e r la y .
T h e tr a f f i c
T h e f i r s t s te p in th e o v e r a l l
p r o je c t i s th u s th e e s ta b lis h m e n t of a to ta lly g ra p h ic s to r a g e file .
T h e b o u n d a ry d a ta a r e m e tr ic a lly c o d e d a n d t r a n s f e r r e d f r o m g ra p h ic to n o n g r a p h ic s to r a g e b y u s in g a d ig i tiz e r to r e c o r d a s e r i e s of d is c r e te p o in ts th a t
d efin e e a c h p o ly g o n .
T h e a r e a o f e a c h p o ly g o n i s c o n s id e r e d to b e c o m p le te ly
e n c lo s e d b y a b o r d e r c o m p o se d of s tr a i g h t lin e s e g m e n ts jo in in g th e p o in ts .
(C u rv e d li n e s a r e a p p ro x im a te d b y s u c h s tr a i g h t lin e s e g m e n ts .) E a c h
in d iv id u a l p o ly g o n i s to t a ll y e n c lo s e d b y a s e r i e s of p o in ts , s o a l l li n e s o n
th e m a p a r e r e c o r d e d tw ic e .
T h e p o s itio n s o f th e p o in ts a r e v is u a lly
s e le c te d b y th e o p e r a t o r ; th e n u m b e r r e q u i r e d to d e fin e a p o ly g o n v a r i e s w ith
146
th e s iz e a n d c o n fig u ra tio n o f th e p o ly g o n .
T h e fin e s t re s o lu tio n u s e d is
a p p r o x im a te ly 50 p o in ts p e r li n e a r in c h of p o ly g o n b o u n d a ry , b u t th e a v e ra g e
is s u b s t a n ti a ll y l e s s th a n th a t.
A t o t a l of 6 ,0 0 0 ,0 0 0 p o in ts h av e b e e n u s e d to
d efin e 3 0 ,0 0 0 p o ly g o n s, a n a v e ra g e of 200 p o in ts p e r in d iv id u a l polygon
re c o rd .
T h e r e c o r d s iz e , h o w e v e r, v a r i e s w id e ly .
E a c h p o ly g o n i s a ls o
a s s ig n e d th e c o o rd in a te s of a c o n ta in e d c e n tr o id v is u a lly e s tim a te d b y th e
o p e ra to r.
In a d d itio n , s e v e r a l s ig n ific a n t it e m s o f d a ta a r e a d d e d to th e c o n te n t of
e a c h p o ly g o n r e c o r d .
E a c h p o ly g o n is a s s ig n e d a u n iq u e n u m b e r (a c o m b in a -
tio n of th e m a p n u m b e r a n d th e p o ly g o n n u m b e r w ith in th e m a p ).
C lo s e s t
p o ly g o n s a r e n u m b e r e d c o n s e c u tiv e ly to a c h ie v e s o m e e ff ic ie n c ie s in
s u b s e q u e n t g ro u p in g an d p r o c e s s in g p r o c e d u r e s .1
T h e d e s c r ip tiv e d a ta
r e l a t i n g to th e p o ly g o n a r e e n te r e d a s p a r t of th e polygon r e c o r d .
(S o il d a ta
a l p h a n u m e r ic s a r e t r a n s f o r m e d to a n u m e r ic c o d e s o th a t th e y c a n b e e n te r e d
th ro u g h th e d ig i tiz e r k e y b o a r d .) E a c h p o ly g o n i s a s s ig n e d a co d e b y th e
o p e r a t o r to d is tin g u is h n o r m a l p o ly g o n s , in c o m p le te p o ly g o n s (th o s e a t m ap
b o r d e r s ) , a n d p o ly g o n s w h o lly c o n ta in e d w ith in o th e r p o ly g o n s (th e is la n d
ca se).
A co u n t o f th e to t a l n u m b e r o f p o in ts r e q u i r e d to d e s c r ib e th e p o ly g o n
i s a u to m a tic a lly a s s ig n e d to e a c h p o ly g o n r e c o r d b y th e d ig itiz e r .
F o r e a c h s h e e t , th e c o o rd in a te a x is of th e d ig i tiz e r ta b le i s m a n u a lly a lig n e d
to th e a x is of th e P la n e C o o rd in a te S y s te m r e f e r e n c e p o in ts o n th e m a p to
e l im i n a te th e n e e d f o r s u b s e q u e n t c a lc u la tio n of c o o rd in a te r o ta tio n .
The
ta b le c o o r d in a te s of th e r e f e r e n c e p o in ts a r e r e c o r d e d f o r e a c h m a p , th e
u p p e r le f t r e f e r e n c e p o in t b e in g a s s ig n e d a ta b le c o o rd in a te v a lu e o f 0 .0 .
T h e e f f o r t e x p e n d e d in d ig itiz in g a lo n e , e x c lu d in g e r r o r c h e c k in g an d
r e d i g iti z in g , to o k 218 m a n -d a y s a n d c o s t $ 1 0 ,2 4 0 .0 0 , e x c lu d in g o v e rh e a d .
T h e s e f i g u r e s r e f l e c t th e le v e l of d e n s ity an d c o m p le x ity of c o n fig u ra tio n of
th e s o u r c e d a ta .
H a rd w a re p ro b le m s a ls o c o n trib u te d to th e a m o u n t of e ffo rt
in v o lv e d (th o u g h th e s e a r e not u n u s u a l in th i s ty p e of d ev e lo p m en t).
D a n g e rm o n d 2 e s ti m a t e s th a t o v e r a l l d ig itiz in g c o s ts cou ld b e lo w e r e d b y 30%
i n a p ro d u c tio n o p e r a tio n .
A n in s p e c tio n of th e s p a ti a l c o n n e c tiv itie s in h e r e n t in th e d a ta r e c o r d s
1. T h i s i s a lo o s e f o r m of to p o lo g ic a l c o n n e c tiv ity coding , b u t i s n o t rig o r o u s
e n o u g h f o r s u b s e q u e n t u s e a s a c o n n e c tiv ity in d ic a to r . 2. D a n g e rm o n d 1971.
147
p ro d u c e d b y th e d ig itiz in g p r o c e s s m a k e s i t p o s s ib le to u n d e rs ta n d th e s u b s e q u e n t p r o c e s s in g s te p s u s e d to p ro d u c e a n in te r n a lly c o n s is te n t n o n - g r a p h ic
f il e .
A s a r e s u l t of th e d ig itiz in g p r o c e s s , p o in ts a r e s p e c ifie d b y m e tr ic
c o d e s a n d t h e i r s p a ti a l r e l a ti o n s h i p to one a n o th e r i s d efin ed b y t h e ir
s e q u e n c e w ith in th e lin e s e g m e n t r e c o r d s .
S im ila rly , th e re la tio n s h ip of
th e lin e s e g m e n ts (th e s t r a i g h t lin e c o n n e c tio n p o in ts) to one a n o th e r is
e s ta b lis h e d b y t h e i r s e q u e n c e in a p o ly g o n r e c o r d (and o n ly o ne po ly g o n
re c o rd ).
S p a tia l c o n n e c tiv ity b e tw e e n p o ly g o n s is e x p lic it o n ly in th e m e tr ic
c o d e s of th e b o u n d a ry p o in ts u s e d to d efin e th e m .
T h e c e n tr o id c o o rd in a te s
o r th e u n iq u e n u m b e r a s s ig n e d to e a c h p o ly g o n w ould s e e m to b e a m e n a b le
t o to p o lo g ic a l c o n n e c tiv ity c o d in g , b u t n o n e h a s b e e n a tte m p te d .
M a p -to -m a p
c o n n e c tiv ity is lo o s e ly d e fin e d b y th e m a p n u m b e rin g s y s te m , b u t is e x p lic it
o n ly in th e c o o rd in a te v a lu e s a s s ig n e d to th e ed g e r e f e r e n c e p o in ts.
The
s p e c if ic a tio n of s p a ti a l c o n n e c tiv ity th u s l i e s w ith in th e m e tr ic c o d in g of th e
d a ta s e t .
T h e s p a ti a l a s p e c t s of s u b s e q u e n t f il e c r e a tio n a r e in itia lly c o n -
c e r n e d w ith a c h ie v in g a n i n t e r n a l ly c o n s is te n t m e tr ic s tr u c t u r e .
Such a
s y s t e m s h o u ld allow e d itin g a n d c o r r e c tio n of e r r o r s in th e c o o rd in a te r e c o r d s .
A s s u m in g th a t a c o m p le te m a p i s n o t d ig itiz e d at one tim e , th e n th e r e m u s t
b e a w a y to in c lu d e p o ly g o n s in o n e s e t to f o r m a c o m p le te m a p o r s e t of
m a p s.
A s s u m in g th a t m o r e th a n one m a p i s d ig itiz e d , th e r e m u s t b e a
p r o c e s s to lin k th e m e t r i c c o d e s of in c o m p le te p o ly g o n s to f o r m w h o le p o ly go n s (ed g e m a tc h in g ).
If s u b s e q u e n t p r o c e s s in g i s to b e e f fic ie n t, t h e r e m u s t
b e a p r o c e s s to c o n v e rt th e c o o rd in a te d e s c r ip tio n of th e f ile to a u n if o r m
b ase.
S u b se q u e n t d a ta m a n ip u la tio n s s u c h a s d a ta r e t r i e v a l , m e a s u r e m e n t,
an d c o m p a r is o n w ill p ro b a b ly n e e d to b e b a s e d on th e m e tr ic p r o p e r t ie s of
th e f ile .
T h is in d e e d o c c u r s in P IO S .
A f te r th e d ig itiz in g p r o c e s s i s c o m p le te d , s o m e in itia l s te p s in c o r p o r a te d in
th e p r o g r a m s ST O R E AND E D IT , PO L Y G O N M ER G E, a n d M AP M ERG E a r e
gone th ro u g h to f a c i li ta te s u b s e q u e n t p r o c e s s in g .
W ith th e s e p r o g r a m s ,
e a c h p o ly g o n r e c o r d i s e d ite d f o r s u c h ite m s a s c lo s u r e , f o r m a t, and
c o r r e c t c o n te n ts (none m i s s in g o r e x c e e d in g g iv e n lim its ) .
In th e p r o c e s s ,
th e e x t r e m i ty c o o r d in a te s of th e p o ly g o n a r e d e te rm in e d a n d a d d e d to th e
p o ly g o n r e c o r d .
T h e p o ly g o n s a r e p lo tte d u s in g an a u to m a tic d r a f tin g
148
m a c h in e u n d e r c o n tr o l of th e c o m p u te r a n d th e r e s u lt in g g r a p h ic r e p r e s e n t a t i o n of th e d ig ita l r e c o r d i s v is u a lly in s p e c te d to d e te r m in e in a c c u r a c ie s ,
p a r t i c u l a r l y n o n -lo g ic a l e r r o r s s u c h a s th o s e r e s u lt in g f r o m d ig i tiz e r d r if t,
in c o r r e c t s e t- u p , o r o th e r s .
(T h e s e p r o b le m s w ill b e d is c u s s e d m o r e
f u lly in a l a t e r p a r t of th i s c h a p te r .) I n a c c u r a te p o ly g o n s a r e r e d i g iti z e d
a n d th e new r e c o r d s a r e ex c h a n g e d f o r th e o ld on th e b a s i s o f p o ly g o n
n u m b e rs .
F in a lly , th e p o ly g o n c o o r d in a te s a r e c h a n g e d f r o m th o s e o f th e
d ig i tiz e r ta b le t o s ta t e p la n e c o o r d in a te s , b y e m p lo y in g th e s ta t e p la n e
c o o rd in a te v a lu e s of th e r e f e r e n c e p o in ts o n th e b o r d e r of e a c h m a p .
The
f il e th a t r e s u l t s f r o m th e s e o p e r a tio n s i s te r m e d th e B a s e M ap M a s te r F ile .
T h e n e x t s e r i e s of o p e ra tio n s i s d e s ig n e d t o r e m o v e th e b a s e m a p b o r d e r s
,
c o n s tr u c t c o m p le te r e c o r d s f o r p o ly g o n s th a t c o n ta in o th e r s , c o m p u te a r e a s
a n d c e n tr o id s , c o n v e rt polygon v e r t ic e s to c e n tr o id r e l a ti v e c o o r d in a te s , a n d
c r e a t e th e P IO S M a s te r F i l e w ith a m p lifie d d e s c r i p tiv e d a ta .
T h e s e fu n c tio n s
a r e p e r f o r m e d b y th e in te r a c tio n of t h r e e p r o g r a m s (L IS T , C O N N E C T , an d
IN S E R T ).
T h e LIS T p r o g r a m i s u s e d to p ro d u c e a l i s t of th e n u m b e r s o f th e
b o r d e r (in c o m p le te ) a n d n e s te d ( is la n d c a se ) p o ly g o n s f r o m th e s h o o ts b e in g
jo in e d .
T h e l i s t e d n u m b e rs of th e a p p r o p r ia te p o ly g o n s a r e m a tc h e d b y
v is u a l in s p e c tio n of th e g ra p h ic s o u r c e m a te r i a l.
T h e r e a f te r , a te m p o r a r y
f i l e i s g e n e ra te d w hich c o n ta in s th e r e s u l t s of th i s v is u a l p r o c e s s in th e f o r m
o f a n in d e x e d s e q u e n tia l s e t of p o ly g o n s .
O ne p a s s of th e p r o g r a m CO NN EC T
us e s a s e a r c h r a d iu s te c h n iq u e to m a tc h c o o r d in a te s tr in g s i n a d ja c e n t
b o r d e r p o ly g o n s f r o m a d ja c e n t m a p s .
c
T h e s a m e a p p ro a c h is u s e d t o i n s e r t
o n ta in e d (n este d ) p o ly g o n s in to th e f il e b y a m a n u a l m a tc h fo llo w e d b y
m a c h in e m e r g e , th o u g h in th i s c a s e th e m e r g e i s a c h ie v e d u s in g th e IN SE R T
p ro g ram .
T h e IN SE R T p r o g r a m a l s o c a lc u la te s th e a r e a o f e a c h p o ly g o n
(u s in g S im p s o n 's r u le ) , a n d c a lc u la te s a "c e n tr o id " (u s in g a s tr a ig h tf o r w a r d
c e n t r e - o f - g r a v i t y s o lu tio n ; th e r e s u lt in g p o in t i s e x p r e s s e d in s ta t e p la n e
c
o o r d in a te s , a n d m a y b e w ith in o r o u ts id e th e po ly g o n ).
The sam e p ro g ra m
c o n v e r ts th e p o ly g o n v e r t e x c o o rd in a te s to c e n tr o id r e l a ti v e c o o r d in a te s .
T h is l a t t e r s te p f a c i l i t a t e s c e r t a i n s u b se q u e n t m a n ip u la tio n s , in c lu d in g a
s im p lif ie d v e r s io n of p r o je c ti o n c h a n g e , u s in g s u c h p r o g r a m s a s th o s e
a v a ila b le i n th e AUT O M A P s y s t e m b u t p e r f o r m e d o n th e c a lc u la te d c e n tr o id s
r a t h e r th a n o n a l l v e r t e x c o o r d in a te s .
In a d d itio n , th e IN SE R T p r o g r a m
14 9
w r i t e s l i t e r a l r e c o r d s u b tit le s in to th e d e s c r ip tiv e r e c o r d , s u c h a s SOILS,
T R A F F IC , C S P C (C a lifo r n ia S ta te P la n e C o o rd in a te s ), a s a p p r o p r ia te in
each case.
T h e r e s u lt in g f il e (PIO S M a s te r F ile ) i s th u s a s e q u e n tia l s e t
o f p o ly g o n r e c o r d s , e a c h r e c o r d h a v in g a n in d e x e d s e q u e n tia l s tr u c t u r e ,
w ith a r e l a ti v e ly s o p h is tic a te d s e t of in s e r t e d an d c a lc u la te d d a ta c o n te n ts .
T h e fo llo w in g e x a m p le i s a n in d ic a tio n of th e le v e l of e ffo rt r e q u i r e d f o r
a n a v e r a g e m a p to b e p r o c e s s e d th ro u g h th e ab o v e s te p s f r o m d ig itiz a tio n
to P I OS M a s te r F ile .
p o ly g o n s .
T h e m a p u s e d a s a n e x a m p le c o n ta in s 3 ,1 0 0 s o ils
T h e ti m e s g iv e n a r e f o r s in g le r u n s of e a c h of th e p r o g r a m s .
T h e r u n s w e r e m a d e on a n IB M 3 6 0 /5 0 , 256K , w ith a C alco m p 566 3 0 -in .
p lo t te r .
R u n tim e s
C o m p u te r p r o c e d u r e s
1)
S to re a n d e d itin g ( s e v e r a l r u n s to g e t to t a l m ap)
17. 3 m in cp u
2)
M e rg e p r o g r a m ( s e v e r a l r u n s to g e t to t a l map)
19. 7 m in cp u
3)
P l o t t e r r uns
4)
E d itin g ru n
5)
8. 1 m in cp u
4. 2 h p lo ttin g tim e
8. 7 m in cp u
37. 7 m in cp u
C o n v e rt ru n
T a b le 5. 2.
P IO S : c o m p u te r ti m e r e q u i r e d to p r o c e s s a n a v e ra g e m ap
f r o m d ig itiz a tio n to M a s te r F ile f o r m a t.
S e v e r a l k in d s of m a n ip u la tio n c a n b e p e r f o r m e d on th e P IO S M a s te r F ile .
T h e LIS T p r o g r a m ca n b e u s e d to l i s t an d s u m m a r iz e poly g o n s b y ty p e ,
w h ich c a n b e s p e c ifie d b y a n y of th e c h a r a c t e r i s t i c s in th e p o ly g o n r e c o r d
(s e e a b o v e ).
T h is r e p r e s e n t s a v a lu a b le c a p a b ility f o r s e le c tiv e r e t r i e v a l .
T h e P IO S M a s te r F ile c a n b e u p d a te d u s in g th e IN PU T p ro g r a m .
B y m a n u a lly
s p e c ify in g th e c h a n g e s on new p u n ch c a r d s , it is p o s s ib le to ad d , r e p l a c e ,
o r d e le te p o ly g o n s , a n d to ch a n g e d e s c r ip tiv e in fo rm a tio n .
H o w e v e r, th i s
m a y r e q u i r e la b o r io u s m a n u a l p r e p a r a tio n of pu n ch c a rd s u n le s s th e
c h a n g e s in v o lv e s m a l l a m o u n ts of d a ta .
T h e M ASTER F I L E P L O T p r o g r a m
w ill c a u s e th e a u to m a tic p lo ttin g ta b le to d ra w m a p s of th e p o ly g o n f i l e o r
p o r ti o n s of th e f il e (s e e "w indow " c a p a b ility below ), a t any s c a le , s u ita b ly
g r id d e d a n d title d .
D e s c rip tiv e a n n o ta tio n s a r e p la c e d a t th e e s tim a te d
c e n tr o id c o n ta in e d w ith in e a c h p o ly g o n ( r a t h e r th a n a t th e c a lc u la te d c e n tro id ).
W e ig h te d s h a d in g c a n b e a s s ig n e d to s p e c ifie d a r e a s .
An a lte r n a tiv e f o r m
150
of g r a p h ic d is p la y i s to a llo c a te d e s c r i p tiv e d a ta of th e poly g o n s to t h e i r
c e n tr o id s a n d u s e th e r e s u lt in g p o in t d a ta a s a n in p u t to s y s te m s o f th e
SYM AP ty p e ; in o th e r w o rd s , a g r id c e ll d a ta b a n k of any c e ll s iz e c a n b e
c r e a te d .
S im ila r ly , s u c h p o in t d a ta c o u ld b e u s e d in any p o in t d a ta h an d lin g
s y s t e m , c o u ld b e a g g r e g a te d b y p o in t-in -p o ly g o n te c h n iq u e s , a n d co u ld b e
u s e d in c o m p a r a tiv e s t a t i s t i c a l o r s in g le v a r ia b le a n a ly s is .
T h e se m odal
ch a n g e p r o c e d u r e s do, of c o u r s e , in c o r p o r a te a l l th e lim ita tio n s of th e
r e s u lt in g d a ta f o r m a ts d is c u s s e d in C h a p te r 4 , pp.
9 5 -9 7 , a lth o u g h th e y
h a v e s o m e v a lu e f o r p la n n in g s tu d ie s th a t in v o lv e s m a l l- s c a l e g r id te c h n iq u e s .
M o re in t e r e s t i n g a r e th e "w indow ing" an d " o v e r la y " c a p a b ilitie s .
The
w indow ing te c h n iq u e a llo w s r e c t a n g u la r a r e a s to b e s o r te d o u t o f th e m a s t e r
f il e f o r s u b s e q u e n t c o m p u ta tio n a n d a n a ly s is o r g ra p h ic d is p la y .
The
r e c t a n g u la r a r e a r e q u i r e d i s s p e c if ie d b y c o o r d in a te s and th e p r o g r a m
c r e a t e s a w o rk f il e th a t c o n ta in s th o s e p o ly g o n s w h o se e x t r e m i tie s f a l l
w ith in th e r e c t a n g le , th a t i s , w ith in th e s p e c ifie d "w indow ".
T h is l i m it s
th e s iz e o f f il e to b e a c c e s s e d f o r s u b s e q u e n t p r o c e s s in g , p a r t ic u l a r ly f o r
o v e r la y p u r p o s e s .
O v e rla y in g i s th e p r o c e s s of s u p e rim p o s in g tw o o r m o re d a ta s e t s s u c h th a t
th e f in a l d a t a s e t p r o d u c e d c o n ta in s th e in fo r m a tio n f r o m b o th o r a l l of th e
o r ig i n a l d a ta s e t s .
A s th e n u m b e r of o v e r la y s a n d m a p c o m p le x ity g ro w ,
s o do th e c o s t a n d d o u b ts about r e p r o d u c ib ility .
T h is is o b v io u sly a v e r y
e x p e n siv e a n d tim e - c o n s u m in g p r o c e s s f o r c o m p le x s itu a tio n s , alth o u g h i t
m a y b e a c c e p ta b le f o r s im p le o n e s .
i s b a s e d o n s e v e r a l a s s u m p tio n s .
T h e o v e r la y p r o c e s s e m p lo y e d in P IO S
T h e d a ta s e t s to b e o v e r la id a r e , of c o u r s e ,
s e t s of d e fin e d , s tr a i g h t- s id e d p o ly g o n s .
It i s a s s u m e d th a t th e a v e ra g e
s iz e of o n e of th e p o ly g o n s of one s e t (th e tr a f f i c zone) i s s u b s ta n tia lly l a r g e r
th a n th e a v e ra g e s iz e of p o ly g o n s in th e s e c o n d s e t (th e s o il m a p s), an d th a t
th e l a t t e r a r e to b e a g g re g a te d w ith in th e f o r m e r .
It i s a ls o a s s u m e d th a t th e
d a ta s e t s a r e of li m it e d s iz e (th is i s e n s u r e d by th e a b ility to "w indow " th e
r e q u i r e d a r e a s ) , a n d th a t o n ly tw o s e t s of d a ta a r e b e in g o v e r la id a t one ti m e .
V a rio u s a p p r o a c h e s to th e ta s k of o v e r la y a r e a v a ila b le .1
T h e a p p ro a c h
c h o s e n b y th e d e s ig n e r s of P IO S 2 r e f l e c ts th e n e c e s s a r y b a la n c e b e tw e e n
1. A rm s 1968. S ee re v ie w of o v e r la y te c h n iq u e s , pp. 795-805 in T o m lin s o n , R .F .
1972. 2. D a n g e rm o n d 1971.
151
e ffic ie n c y of p r o c e s s in g a n d th e c o r e s to r a g e r e q u i r e m e n t s n e e d e d to r u n th e
p r o g r a m , g iv e n th e o v e r la y a s s u m p tio n s m e n tio n e d ab o v e.
T h e a lg o r ith m
u s e d e m p lo y s a n e ffic ie n t poly g o n s u b d iv is io n te c h n iq u e w h ich p a r titio n s th e
l a r g e r p o ly g o n s f o r su b se q u e n t p o in t- in - p o ly g o n c a lc u la tio n s to d e te r m in e
w h ic h v e r t i c e s of th e s u b o rd in a te p o ly g o n s a r e c o n ta in e d w ith in th e m , and
h e n c e w h ic h p a r t s of th e s u b o rd in a te p o ly g o n s a r e c o n ta in e d .
E a c h d o m i-
n a n t p o ly g o n (tr a f f ic zone) i s d iv id e d in to 16 s t r i p s of e q u a l w id th , p a r a l le l
to th e X a x i s . E a c h s t r i p i s th u s a n ew ly d e fin e d s u b -p o ly g o n , w h ich i s s to r e d
in a n a r r a y .
E a c h p o in t in th e s u b o rd in a te p o ly g o n i s r e a d in to th e a r r a y an d
i s t e s t e d to d e te r m in e w h e th e r i t is in o r out of th i s s t r i p of th e m a jo r p o ly gon.
A s th e p o in t-in -p o ly g o n te c h n iq u e o p e r a t e s p a r a l l e l to th e s t r i p 's
lo n g itu d in a l d ir e c tio n , th e t e s t n e e d o n ly b e a p p lie d w ith in th e s t r i p an d th e
r e s t of th e d o m in a n t p o ly g o n n e e d n o t b e c o n s id e r e d .
A f te r th e s p e c i a l c a s e
o f lo c a tin g th e f i r s t p o in t h a s b e e n c o n s id e r e d , s u c c e s s iv e p o in ts d efin e lin e
s e g m e n ts th a t a r e c o n ta in e d w ith in , i n t e r s e c t , o r a r e o u ts id e th e d o m in an t
p o ly g o n .
T h o s e c o n ta in e d a r e r e c o r d e d in a m e m o r y ta b le .
T hose in te r-
s e c t in g allow th e in t e r s e c ti o n p o in t to b e c a lc u la te d , th e tr u n c a te d lin e
s e g m e n t to b e s to r e d in th e m e m o ry ta b le , a n d a c lo c k w is e ch a n g e in
d ir e c ti o n to b e m a d e to p ro c e e d to th e n e x t p o in t.
In th is m a n n e r th e new
(o v e rla id ) p o ly g o n s a r e d ev e lo p ed an d t h e i r a r e a s a r e s u b s e q u e n tly co m p u ted .
T h e r e s u lt in g p o ly g o n s iz e s a r e s u m m a r iz e d b y ty p e w ith in th e d o m in an t
p o ly g o n s .
T h is is a n e x t r e m e l y s tr a ig h tf o r w a r d a p p ro a c h to poly g o n o v e r la y , a n d th e .
p r e l i m i n a r y a s s u m p tio n s m a d e a n d d e s c r i b e d ab o v e e lim in a te th e m a jo r ity
o f p r o b le m s in h e r e n t in m o re c o m p le x p o ly g o n o v e r la y t a s k s ( s u c h a s im a g e
b la c k e n in g , s m a l l a r e a c r e a tio n , e x c e s s iv e d a ta v o lu m e c r e a tio n , c o in c id in g
b o u n d a r ie s , c o a s tlin e w e a v e , a n d i m m e r s e d b o u n d a rie s ).
T h e few p r o b le m s
th a t a r i s e a r e v is u a lly e x a m in e d in a g r a p h ic p lo t of th e f il e r e s u lt in g f r o m
o v e r l a y a n d a r e c o r r e c t e d m a n u a lly .
In c o n s e q u e n c e , th e co m p u tin g tim e s
f o r th e o v e r l a y p r o c e s s e s a r e s h o r t.
T h e s im p l e s t e a s e , w h e r e tw o p o ly g o n s
a r e o v e r l a id one on th e o th e r a n d h a v e tw o in t e r s e c ti o n p o in ts , h a s an
a v e r a g e c o m p u ta tio n tim e of 0. 8 s e c o f cp u ti m e .
A ty p ic a l w indow c o n -
ta in in g 400 s o il zone poly g o n s o v e r la id b y o n e t r a f f i c zone c a n b e a n a ly s e d
152
in l e s s th a n 1 m in of cpu ti m e , o r a n a v e ra g e of 6. 6 poly g o n c o m p a r is o n s
p e r s e c.
(A c o n s id e r a b le p e r c e n ta g e of th e 400 p o ly g o n s in v o lv ed in s u c h an
e x a m p le w ill n o t b e in c lu d e d in th e d o m in a n t p o ly g o n an d h e n c e w ill n o t b e
p r o c e s s e d .) T h e o v e r a l l e ffo r t to o v e r la y a l l of b o th d a ta s e t s in th e P IO S
p r o je c t c o s t $ 4 , 200. 00 f o r c o m p u te r ti m e a n d $ 1 3 0 .0 0 f o r la b o u r , an d w as
c o m p le te d in 2 d a y s .
F in e P o ly g o n S y s te m s : th e E x a m p le o f CGIS
P r o b a b ly th e m o s t c o m p re h e n s iv e s y s t e m d e s ig n e d w ith fin e p o ly g o n s a s a
p r i m a r y s to r a g e f o r m a t i s th e C a n a d a G e o g ra p h ic I n fo rm a tio n S y s te m (CGIS).
A lth o u g h th e s y s t e m i s c u r r e n t ly in o p e r a tio n a t th e D e p a rtm e n t o f th e E n v ir o n m e n t, G o v e rn m e n t of C a n a d a , O tta w a , th e s y s t e m f a c i li tie s a r e u n d e r c o n tin u in g d e v e lo p m e n t.
A f u ll te c h n ic a l d e s c r i p tio n of CGIS i s g iv e n in th e
A ppendix.
T h e a p p ro a c h u s e d in CGIS i s , f i r s t , to t r a n s f o r m th e g ra p h ic d a ta in to a
s tr u c t u r e d , n o n -g ra p h ic fo rm a t, a m e n a b le to c o m p u te r p r o c e s s in g , an d
s e c o n d ly , to p ro v id e a s e t of p r o c e d u r e s th a t c a n e ff ic ie n tly o p e r a te o n th e
s t o r e d d ata.
T h e s e tw o s te p s a r e c o n c e p tu a lly d is tin c t.
T h e c r e a tio n o f
th e d a ta b a n k in v o lv e s th e p r o c e s s in g of s o u r c e d a ta by a u n if o r m s e t of
o p e r a tio n s .
O nly th e d a ta , o r a t m o s t a few p a r a m e t e r s , ch a n g e.
T h is s e t
s e r i e s of o p e r a tio n s , o r " p h a s e s " a s th e y a r e r e f e r r e d to in th e CGIS,
r e m a in s c o n s ta n t a n d is e x e c u te d u n d e r th e r e s id e n t o p e r a tin g s y s t e m of
th e c o m p u te r.
T h e s u b se q u e n t m a n ip u la tio n an d r e t r i e v a l o f th e d a ta , o n
th e o th e r h a n d , a r e m a d e u p of s e ts of p r o c e s s e s th a t c a n v a r y f o r e a c h u s e r
and each u se.
T h e s e q u e n c e an d ty p e of o p e r a tio n s m a y ch a n g e w ith e a c h
re q u e s t , f o r e x a m p le , o v e r la y , d is s o lv e , o r m e r g e .
E a c h r e q u e s t h a s to
b e p ro v id e d w ith i t s ow n "jo b s t r e a m " , w h ic h c a n b e co m p le x to s e t up,
tim e c o n su m in g , an d p r o n e to e r r o r u n le s s a u to m a te d .
A c c o rd in g ly , a
" m o n ito r" s y s t e m i s a b a s i c n e e d of th e r e t r i e v a l p r o c e s s .
It f a c i li ta te s
a n d c o o rd in a te s th e o p e ra tio n s n ee d ed , to m a n ip u la te th e d a ta b a n k , a n d a ls o
h a s a s p e c ia l c o m p ile r th a t a llo w s a n u m b e r of c o m m a n d s f o r g r a p h ic d a ta
h a n d lin g to b e e x p r e s s e d in a n E n g l is h - lik e la n g u a g e .
r e q u e s t s ca n b e in ta b u la r o r p lo tte d lin e f o r m .
1. T o m lin s o n , R . F . 1967, 1968.
T h e o u tp u t f r o m
153
S y ste m
li b r a r y
G ra p h ic
so u rce
d a ta
G ra p h ic to
n o n -g ra p h ic
c o n v e rs io n
In p u t
p hases
0 - 8
D ata
b an k
R e tr ie v a l
m o n ito r
R e q u e s ts
O utput
( p r in te r o r
p lo tte r )
IN P U T P R O C E S S
(U n d er c o n tr o l of o p e r a tin g s y s te m )
R E T R IE V A L PR O C E SS
(U nder c o n tr o l of r e t r i e v a l
m o n ito r)
F ig . 5. 10. CGIS: o v e r a l l s y s t e m c o n c e p t.
T h e f i r s t f u n c tio n of th e s y s t e m i s to c o n v e rt th e g r a p h ic s o u r c e d a ta to a
s im p le n o n -g r a p h ic f o r m a t.
T h e o p e ra tio n s in v o lv ed in th i s p r o c e s s a r e
il l u s t r a t e d in th e d ia g r a m (F ig . 5 .1 1 ) b elo w , b u t it m a y b e n o te d th a t th e
g ra p h ic s o u r c e d a ta a r e p r o v id e d a s h a n d -d ra w n a n n o ta tio n s on tr a n s lu c e n t,
s t a b l e - b a s e r e p r o d u c tio n s o f to p o g ra p h ic m a p s .
i s h ig h .
T h e v o lu m e of s o u r c e d a ta
O v e r 1 5 ,0 0 0 2 0 -in . x 3 0 -in . s h e e ts h a v e a lr e a d y b e e n r e c e iv e d f o r
s y s t e m p r o c e s s in g .
T h e s o u r c e d a ta a r e p r e p a r e d f o r co d in g b y tr a c in g
(s c rib in g ) th e im a g e (b o u n d a ry lin e ) d a ta on s e p a r a t e s h e e ts , b y s e q u e n tia lly
n u m b e rin g 1 e a c h g r a p h ic d a ta e le m e n t on e a c h s h e e t, an d b y c r e a tin g a
s e q u e n tia lly n u m b e re d l i s t of th e a lp h a n u m e ric d e s c r i p to r s th a t a p p ly to
e a c h g ra p h ic d a ta e le m e n t on e a c h s h e e t.
T h u s p r e p a r e d , th e im a g e d a ta a r e s c a n n e d w ith a d r u m s c a n n e r 2 (s e e F ig .
5. 11) to c r e a t e a m a g n e tic ta p e of th e im a g e .
T h e s e q u e n tia lly n u m b e re d
a lp h a n u m e r ic d e s c r i p t o r s a r e k e y e d 3 d ir e c tl y on m a g n e tic ta p e .
T o lin k
th e im a g e an d d e s c r i p t o r d a ta s e t s , a d ig i tiz e r p ro d u c e s a th i r d m a g n e tic
ta p e th a t co n ta in s th e c o o r d in a te s of a p o in t f o r e a c h s e q u e n tia lly n u m b e re d
d a ta e le m e n t (u s u a lly a v is u a lly e s tim a te d , c o n ta in e d c e n tr o id f o r po ly g o n
1. T h is p r o c e s s i s d u p lic a te d to allow d a ta to b e v e r if ie d d u rin g s u b se q u e n t
e d itin g p r o c e d u r e s . 2. T h o m p so n 1967. 3. T h is p r o c e s s is d u p lic a te d to
allow d a ta to b e v e r i f ie d d u r in g s u b s e q u e n t e d itin g p r o c e d u r e s .
154
d a ta ).
T h e n u m b e r i s c o m m o n to th e p o in t a n d to th e a lp h a n u m e ric d e s c r i p ­
t o r o f th e d a ta e le m e n t.
T h e c o o rd in a te s o f th e po in t c a n b e m e tr ic a lly
r e l a t e d to th e c o o r d in a te s of th e im a g e r e c o r d .
A r e c o r d i s a ls o m a d e o f
c e r t a i n d a ta , s u c h a s m a p s c a l e , la titu d e an d lo n g itu d e of m ap c o r n e r p o in ts ,
a n d ty p e of s o u r c e d a ta , to b e u s e d a s c o n tro l in fo rm a tio n in s u b se q u e n t
p r o c e s s in g .
S o u rc e m ap
H IJ
RFT
KL M
CDE
1
2
3
4
S c r ib e d im a g e
ABC
CDE
H IJ
KLM
N u m b e re d o v e r la y
D e s c r ip to r d a ta
X -Y d ig i tiz e r
E ncoder
D ru m s c a n n e r
D e s c r ip to r d a ta w ith r e l a te d
r e f e r e n c e c o o rd in a te s f r o m
d ig itiz e r
Raw m a p im a g e d a ta
D a ta re d u c tio n
s u b s y s te m
F ig . 5 . 11. O p e ra tio n s in v o lv e d in CG IS p r o c e s s of g ra p h ic to n o n -g ra p h ic
c o n v e rs io n .
155
O n ce th e d a t a a r e in n o n -g ra p h ic f o r m , th e fo llo w in g s y s t e m fu n c tio n s a r e
c a r r i e d o u t b y a c o m p u te r.
T h e n o n - g ra p h ic d a ta , b o th im a g e a n d d e s c r ip tiv e , a r e e d ite d f o r v a lid ity .
R ed u n d a n t d a ta a r e e lim in a te d a n d to p o lo g ic a l c o d e s a r e a u to m a tic a lly a d d e d
to th e m e tr ic a lly c o d e d im a g e s .
L in e s e g m e n ts a r e id e n tifie d a s lin e s e g -
m e n ts , a r e o r d e r e d a n d li s t e d , an d a r e a s s ig n e d " d ir e c tio n s " , th a t i s , a r b i t r a r y but c o n s ta n t " r ig h t " an d " le ft" s id e s .
id e n tif ie d a s p o ly g o n s .
S in g le -b o u n d ed p o ly g o n s a r e
T h e c o n n e c tiv ity b e tw e e n p o ly g o n s an d lin e s e g m e n ts
i s s p e c ifie d in a c o d e a u to m a tic a lly a s s ig n e d to e a c h lin e s e g m e n t r e c o r d .
T h e m e t r i c c o d e s of th e im a g e r e c o r d s a r e c o n v e rte d f r o m th e c o o rd in a te
s y s te m s of th e s c a n n e r a n d d ig i tiz e r to a u n if o r m b a s e c o o r d in a te s y s te m ,
th e G e o g ra p h ic a l C o o rd in a te S y s te m (G CS).
W hen a p p lic a b le , th e in p u t s c a le
of th e s o u r c e d a ta i s c o n v e rte d to a s to r a g e s c a l e , a n d i f th i s in v o lv e s s c a le
r e d u c tio n , s in g le - p o in t sm o o th in g of th e li n e s i s c a r r i e d o u t.
T h e e f f e c ts of
l i n e a r d is to r t io n s in th e s o u r c e m a te r i a l a n d a x ia l ro ta tio n o n th e a b s o lu te
p o s itio n o f d a ta e le m e n ts a r e e lim in a te d d u rin g th e s e tr a n s f o r m a tio n s .
The
a r e a of p o ly g o n s i s m e a s u r e d a n d th e c e n tr o id c o o rd in a te s ( c e n t r e s o f m a ss )
o f th e p o ly g o n s a r e c a lc u la te d an d a d d e d to th e p o ly g o n r e c o r d s .
T h e s iz e of
th e im a g e d a ta f i l e i s re d u c e d b y c o n v e rtin g th e m e tr ic c o d e s f o r lin e s e g m e n ts to a c o m p a c t f o r m a t.
T h e f il e c o n ta in in g th e im a g e d a ta i s a u to m a tic a lly
s u b d iv id e d a n d la b e lle d in c o n v e n ie n tly s iz e d b lo c k s (fra m e s ) f o r e a s e o f
s u b s e q u e n t r e t r i e v a l an d p r o c e s s in g ; th e s y s t e m th u s im p a r ts a s t r u c t u r e d
a r e a l d iv is io n to th e im a g e f il e .
P o ly g o n e q u iv a le n c e s a r e r e s o lv e d an d th e
d e s c r i p t o r d a t a a r e m a tc h e d to t h e im a g e d a ta .
T h e s y s t e m a u to m a tic a lly d e t e c ts to p o lo g ic a l e r r o r s an d l i s t s th e e r r o r s
fo u n d in th e f i l e s .
A m a n u a l s u b s y s te m a llo w s e r r o r s to b e c o r r e c te d b y
u s in g m a n u a lly p r e p a r e d c o r r e c t d a t a e le m e n ts to u p d a te th e f il e .
A f te r e r r o r c o r r e c tio n of th e f i l e s , e d g e m a tc h in g i s a c h ie v e d b e tw e e n th e
new s h e e t s of d a ta a n d th e d a ta a l r e a d y s t o r e d in th e d a ta b a n k .
T h e new
d a t a a r e th e n a d d e d to th e d a ta b a n k (d a ta b a n k c re a tio n ).
T h e c o n c e p tu a l fo r m a t of th e d a ta b a n k r e s u lt in g f r o m th e s e p r o c e s s e s is
s h o w n i n F ig s . 5 .1 2 a n d 5 . 13.
156
D ata ty p e
N ext
d a ta ty p e
F ra m e
N ext
fr a m e
P o ly g o n
N ext
polygon
P o in te r
to DDS
O rd ered
se q u e n c e
S e q u e n tia lly
o rd e re d
w ith in f r a m e
DDS
DDS
e tc .
L in e
s e g m e n t #1
L in e s e g m e n ts
th a t c o n s titu te
polygon
S e q u e n tia lly o r d e r e d
in v e r t e x ta b le
L in e
s e g m e n t #n
F ig . 5. 12.
Im a g e D ata S et - L e v e l 1.
T w o m a in d a ta s e t s a r e e s ta b lis h e d : th e im a g e d a ta s e t a n d th e d e s c r i p to r
d a ta s e t.
A n o th e r w is e u n s tr u c t u r e d (le v e l 1) im a g e d a ta s e t (IDS) i s a r r a n g e d b y
d a ta ty p e .
E a c h d a ta ty p e c o n ta in s th e im a g e r e c o r d s f o r e a c h f r a m e ,
w h ic h c o n s is ts of th e m a p e le m e n ts (u s u a lly poly g o n s) th a t m a k e u p th e
fra m e .
E a c h p o ly g o n r e c o r d c o n ta in s th e im a g e r e c o r d s o f th e lin e s e g m e n ts
th a t m a k e up th a t p o ly g o n an d a l s o a p o in te r to th e p a r t of th e d e s c r i p t o r
d a ta s e t th a t c o n ta in s th e d e s c r i p to r a p p ly in g to th a t p olyg o n .
A n o th e r w is e
u n s tr u c t u r e d ( le v e l 1) d e s c r i p to r d a ta s e t (DDS) is a r r a n g e d b y d a t a ty p e .
W ith in e a c h d a ta ty p e th e d e s c r ip tiv e d a ta a r e g iv e n f o r e a c h s e p a r a t e m a p
e le m e n t (u s u a lly a p olygon).
F o r e a c h m a p e le m e n t, p o in te r s a r e p ro v id e d
to th e f r a m e s an d m a p e le m e n ts in th e IDS th a t c o n ta in th e im a g e d a ta f o r
th a t p a r t i c u l a r d e s c r i p to r .
S e v e r a l f r a m e s m a y th u s c o n ta in p a r t i a l r e c o r d s
157
o f th e im a g e d a ta n e e d e d to d e s c r i b e th e b o u n d a ry of one m ap e le m e n t d e s c r i b e d in th e DDS.
N ext
d a ta
ty p e
D a ta
ty p e
M AP
ELEM EN T
M AP
ELEM ENT
A ttr ib u te s
of p o ly g o n
S eq u en ce
n u m b e rs
w ith in
d a ta ty p e
e. g.
P o ly g o n
num ber
e . g.
P o ly g o n
num ber
P o i n t e r s to
f r a m e s in IDS
th a t c o n ta in
p o ly g o n
d itto
d itto
IDS
IDS
F ig . 5. 13.
D e s c r ip t o r D a ta S et - L e v e l 1.
V a rio u s a d d itio n a l l e v e ls of s t r u c t u r e c a n b e im p a r te d to th e DDS b y g ro u p in g
a n d in d e x in g th e m a p e le m e n ts ; th e s u b d iv is io n of a f il e b y re g io n i s a ty p ic a l
e x a m p le .
T h e r e s u lt in g f o r m a t i s sh o w n in F ig . 5. 14.
D a ta ty p e
N ext
d a ta ty p e
L evel 2
s tru c tu re
C la s s
e . g ., re g io n
N ext
c la s s
L evel 3
s tr u c t u r e
S u b c la s s
e .g .,
s u b r e g io n
N ext
s u b c la s s
L evel 1
s tru c tu re
M ap e le m e n t
N ext
m a p e le m e n t
P o in te r s
t o ID S
IDS
F ig . 5. 14. S tr u c tu r e d D e s c r ip t o r D ata S et.
IDS
158
A s n o te d a b o v e , a l l fu n c tio n s of d a ta b a n k m a n ip u la tio n an d r e t r i e v a l a r e
c a r r i e d out u n d e r th e c o n tr o l of a r e t r i e v a l m o n ito r p r o g r a m .
O ne o f th e
b a s i c s y s t e m c a p a b ilitie s is th u s th e a b i lit y to co m b in e m a n ip u la tio n o r
r e t r i e v a l c o m m a n d s , o r b o th , a u to m a tic a lly , w ith th e d e s c r ip tiv e in f o r m a tio n in th e a p p r o p r i a te f il e an d w ith c o m p u te r p r o g r a m s r e s id e n t in th e
s y ste m lib r a r y .
I t g e n e ra te s a c o m p le te r e q u e s t th a t th e c o m p u te r c a n u s e
to e n t e r th e d a t a b a n k an d p ro d u c e th e d e s ir e d a n s w e r in ta b u la r o r p lo tte d
fo rm .
T h e s e t of co d e w o r d s u s e d to s p e c ify th e m a n ip u la tio n a n d r e t r i e v a l
fu n c tio n s m a k e u p th e " c o m m a n d la n g u a g e " .1
T h e m a n ip u la tio n an d r e t r i e v a l
fu n c tio n s c u r r e n t l y in u s e a r e d e s c r ib e d b elo w .
In e a c h c a s e , th e co m m an d
la n g u a g e w o rd o r w o rd s th a t in itia te th e fu n c tio n a r e g iv e n in p a r e n t h e s e s .
W ith in a n y o n e d a ta ty p e (c o v e ra g e in th e d a ta b a n k ), it i s p o s s ib le to r e t r i e v e
a n y d e s ir e d s u b s e t of d a ta .
S p e c ific a lly , one c a n s e le c t (e x tra c t) a l l d a ta
w ith d e s i r e d ID S o r DDS c h a r a c t e r i s t i c s an d a llo c a te a n a m e to th e r e s u ltin g
s u b s e t (S E L E C T , IN C L U D E , N EW NAM E); s e le c t a l l d a ta e x c e p t th o s e w ith
u n d e s ir e d c h a r a c t e r i s t i c s an d n a m e th e r e s u lt in g s u b s e t (S E L E C T , E X C L U D E ,
N EW N A M E); o r s p e c ify a c i r c le o r p o ly g o n w ith in w h ich to a d d r e s s f u r th e r
c o m m a n d s (C IR C L E , POLYG O N).
T h e s t r u c t u r e of a f il e in th e d a ta b a n k ca n b e c h a n g e d , b y s o r tin g th e DDS
in to a d e s ir e d s e q u e n c e of an y c h a r a c t e r i s t i c (DDSORT); b y s p e c ify in g
(la b e llin g ) p a r t s of th e file f o r f u r t h e r in c lu s io n o r e x c lu s io n in p r o c e s s in g
(C O M B IN E , M ER G E); b y e q u a tin g e x is tin g f a c e s in th e f ile an d e f f e c tiv e ly
r e m o v in g th e b o u n d a ry b e tw e e n th e m , s o th a t f o r th e p u r p o s e s of f u r t h e r
r e t r i e v a l th e y w ill b e r e g a r d e d a s one a r e a (DISSOLVE).
T h e c o n te n t of a f ile in th e DDS c a n b e c h a n g e d b y re c la s s if y in g e x is tin g m a p
e le m e n ts in th e f ile .
T h is a llo w s th e a d d itio n a n d d e le tio n of d a ta (DISSOLVE
XXXX F R O M YYYY P O IN T E R , C LA SSIFY XXXX F R O M YYYY P O IN T E R ).
R e c la s s if ic a tio n of th e IDS i s c a r r i e d o u t b y u s in g th e m a n u a l p r o c e s s o f
e r r o r c o r r e c tio n a n d r e p r o c e s s in g th ro u g h in p u t p h a s e s 0 to 8 (a s d e ta ile d
in th e A p p en d ix ).
" M e a s u r e m e n ts " c a n b e c a r r i e d o u t on th e f i l e b y g a th e rin g to g e th e r th e
m e a s u r e m e n t s a l r e a d y m a d e in th e in p u t p h a s e s an d c o n v e rtin g th e m a s
d e s ir e d to u n its of e i th e r a s q u a r e m ile o r a n a c r e (SQMI, A C R E).
1. K in g s to n 1968.
159
T h e c o n te n t of a f i l e c a n b e s e le c tiv e ly r e p o r t e d upon, p r in te d o u t, o r p lo tte d .
T h e w h o le f il e , e i th e r ID S o r DDS, c a n b e p r in te d out (IDSDUM P, D D SLT).
F o r m a t c o n tr o l o f s u c h a p r in to u t o r s e le c te d r e t r i e v a l of p a r t of th e f ile , o r
b o th , c a n b e s p e c if ie d (ASSESS).
w ith o u t th e DDS) c a n b e p lo tte d .
w ith in a r a n g e of x 0 .5 t o x 4 .
A ny s p e c ifie d p a r t of th e ID S (w ith o r
T h e p lo t c a n in c o r p o r a te a s c a le ch a n g e
N u m e ric la b e ls ca n b e p lo tte d a t th e c e n tr o id
o f e a c h fa c e a n d th e a p p r o p r i a te d e s c r i p to r s f r o m th e DDS ca n b e l i s t e d
s e p a r a t e ly b y la b e l n u m b e r (P L O T ).
F r o m m u ltip le d a ta ty p e s (c o v e ra g e s ), i t i s p o s s ib le to e x t r a c t (m ove) b o th
ID S a n d DDS d a ta f r o m th e d a ta b a n k a n d p la c e th e m in th e s y s t e m l i b r a r y in
p r e p a r a tio n f o r f u r t h e r c o m b in e d p r o c e s s in g (CO M BIN E).
A f te r th i s s te p
h a s b e e n ta k e n , a h o v e r la y c a n b e m a d e of o v e rla p p in g d a ta s e t s (O V ER LA Y ).
T h e r e s u lt in g s in g le c o v e ra g e is a m e n a b le to a ll th e m a n ip u la tio n an d
r e t r i e v a l fu n c tio n s m e n tio n e d ab o v e.
S e v e r a l " h o u s e k e e p in g " fu n c tio n s c a n a l s o b e c a r r i e d o ut.
I t i s p o s s ib le to
m o d ify th e s y s t e m p a r a m e t e r s in th e d a ta b a n k a n d in th e s y s t e m l i b r a r y ,
c r e a t e b a c k -u p f i l e s , a n d l i s t th e e x is tin g s y s t e m l i b r a r y (M OD M CCB).
A
m o c k DDS ca n b e c r e a te d f o r te s t in g p u r p o s e s o r f o r g e n e ra tin g a s u b s e t of
d a ta r e l a t e d to a c i r c l e o r p o ly g o n (DDSGENR).
New co m m an d w o r d s c a n
b e s p e c ifie d a n d a d d e d to th e c o m m a n d l i b r a r y (SYSM AT).
It c a n b e s e en f r o m
th e ab o v e d e s c r ip tio n of CGIS fu n c tio n s th a t th e c o s ts of
h a n d lin g s p a tia l d a ta in no n - g r a p h ic f o r m ca n no lo n g e r b e s im p ly r e g a r d e d
a s th o s e a s s o c ia te d w ith c o n v e rtin g th e s o u r c e d a ta to n o n -g ra p h ic f o r m p lu s
th o s e in c u r r e d in r e t r i e v i n g or d e r iv in g m e a s u r e m e n ts an d c o m p a r is o n s f r o m
th e d ata.
At l e a s t t h r e e d i s c r e t e s te p s c a n b e re c o g n iz e d th a t h a v e a c o s t
a s s o c ia te d w ith th e m .
T h e f i r s t r e m a in s th e g ra p h ic to n o n - g r a p h ic c o n v e r -
s io n , a lth o u g h , a s c a n b e s e e n , th i s m a y in c o r p o r a te s e v e r a l d is tin c t
p r o c e s s e s , th e co n tr i b u tiv e c o s t of w h ich m a y v a r y w ith e a c h d a ta s e t.
s e c o n d s te p is d a ta r e d u c tio n arid d a ta b a n k (file s tr u c tu r e ) c r e a tio n .
The
T h is
s te p c a n b e c a r r i e d o u t w ith in th e c o m p u te r b u t m a y in c o r p o r a te s e v e r a l h ig h o r d e r o p e ra tio n s of m e a s u r e m e n t an d c o m p a ris o n , th e r e s u l t s of w h ic h a r e
s to r e d i n th e f il e f o r s u b s e q u e n t r e t r i e v a l .
In th e c a s e o f th e CG IS, th i s s te p
in v o lv e s c h a n g e o f m a p p ro je c tio n , c e n tro id c a lc u la tio n , a r e a m e a s u r e m e n t,
160
li n e a r m e a s u r e m e n t, a u to m a tic a s s ig n m e n t o f n a m e s to f a c i li ta te r e t r i e v a l ,
to p o lo g ic a l e d itin g an d c o r r e c tio n , an d s im p le f o r m s of lin e sm o o th in g ; it
m a y a l s o in v o lv e s c a l e ch a n g e, m e r g e , an d d is s o lv e .
T h e t h i r d s te p i s th e
a c tu a l m a n ip u la tio n , r e t r i e v a l , m e a s u r e m e n t, a n d c o m p a ris o n of d a ta in
th e f il e .
T h is m a y in v o lv e th e r e t r i e v a l a n d g ro u p in g of an y of th e m e a s u r e -
m e n ts c a r r i e d ou t d u rin g th e c r e a tio n of th e d a ta b a n k , o r th e g e n e ra tio n o f
new m e a s u r e m e n ts a n d c o m p a r is o n s , o r b o th .
T h e t a s k of d ir e c tl y c o m p a r in g m a c h in e - a id e d te c h n iq u e s an d e q u iv a le n t
m a n u a l p r o c e s s e s c a n th u s b e e x tr e m e ly d iffic u lt an d m is le a d in g .
For
c o m p a r is o n w ith o n e m a n u a l o p e ra tio n , th e to t a l c o s ts in v o lv ed in c r e a tio n
o f th e w h o le d a ta b a n k r e p r e s e n t a v e r y l a r g e o v e rh e a d b u rd e n f r o m w h ich it
i s im p o s s ib le to s e p a r a t e th e c o m p o n en t p a r t s th a t h a v e c o n trib u te d to th e
e q u iv a le n t c o m p u te r - a id e d o p e r a tio n .
F o r th e s a m e m a n u a l o p e r a tio n , if
r e t r i e v a l c o s ts o n ly a r e e x a m in e d th e r e s u l t m a y b e e q u a lly m is le a d in g , a s
m u c h o f th e n e c e s s a r y p r o c e s s in g m a y h a v e b e e n a c c o m p lis h e d in c r e a tin g
th e n o n - g r a p h ic f ile an d th e r e t r i e v a l c o s ts m a y s e e m u n re a s o n a b ly low .
L e t u s , h o w e v e r, e x a m in e th e c o s ts f o r th e v a r i o u s s ta g e s o f d a ta h an d lin g
in th e CG IS, to g a in an i n i tia l o v e rv ie w of th e e f f o r t in c u r r e d .
T h e m o s t r e c e n t in fo r m a tio n on c o s ts of u s in g th e CGIS is s o m e t e s t r e s u lt s
m a d e a v a ila b le in S e p te m b e r, 1973.
T a b le 5. 3 below is a s u m m a r y of th e
c o s ts f r o m w h ic h s o m e c o n c lu s io n s m a y b e d ra w n .
F i r s t , le t i t b e s a id
th a t th e t e s t d id n o t in v o lv e e i th e r a w id e ra n g e of d a ta ty p e s , o r enough
v o lu m e of d a ta f r o m w h ich to d e r iv e r e l ia b l e e s ti m a t e s f o r a l l ty p e s of d a ta
p r o c e s s in g u s in g th e CGIS.
Such a v o lu m e t e s t i s c u r r e n t ly b e in g d e sig n e d ,
b u t w ill n o t b e a v a ila b le in tim e f o r in c lu s io n in th i s th e s i s .
T he te s t re s u lts
th u s r e f e r o n ly to th e ty p e an d v o lu m e of d a ta b e in g p r o c e s s e d d u rin g th e
t e s t a lo n e .
(H o w e v er, th e d a ta w e r e c h o s e n to b e r e p r e s e n t a ti v e o f ty p e s
c o m m o n ly a v a ila b le to th e s y s t e m .)
T h e s o u r c e d a ta f o r th e t e s t c o m p r is e d f o u r s h e e ts of i r r e g u l a r po ly g o n d a ta
w ith s im p le r e l a t e d d e s c r i p to r d a ta (a tw o - d ig it o r th r e e - d ig it d e s c r i p to r
co d e f o r e a c h p o ly g o n ).
T h e s h e e t s v a r i e d in s iz e an d d a ta d e n s ity .
The
s h e e t d im e n s io n s , poly g o n co u n t, a n d to t a l lin e le n g th s f o r e a c h s h e e t a r e
161
g iv en .
T h e s o u r c e d a ta w e r e p ro v id e d b y th e U n ite d S ta te s G e o lo g ic a l
S u rv e y a n d w e r e b a s e d on U. S. to p o g r a p h ic s h e e ts .
F o r th e c o n v e n ie n c e of
th e CGIS, th e s h e e t s w e r e r e d r a w n to c o n fo rm w ith C a n a d ia n N a tio n a l T o p o g ra p h ic s h e e t s , g iv in g a to t a l of 12 s h e e ts .
ta b u la te d b elo w .
T h e r e s u lt in g d im e n s io n s a r e
T h e p o ly g o n co u n t a n d th e s c a l e r e m a in th e s a m e , th e lin e
le n g th i s a d ju s te d to a c c o m m o d a te th e a d d itio n a l le n g th of s h e e t b o u n d a r ie s
o n ly , th e d a ta d e n s ity is a p p ro x im a te ly h a lv e d , an d th e ch an g e in p o ly g o n
d e n s ity p e r s q u a r e in c h a n d lin e in c h e s p e r s q u a r e in c h a r e ta b u la te d ,
The
f ig u r e s r e l a ti n g to th e s o u r c e d a ta a r e p ro v id e d in th e to p fo u r r o w s of th e
ta b le , a n d th o s e r e l a ti n g to th e C a n a d ia n e q u iv a le n t s h e e ts a r e g iv e n in th e
b o tto m f o u r ro w s ; th e ro w s a r e a r r a n g e d in d e s c e n d in g o r d e r of d a ta d e n s ity
in b o th c a s e s .
T h e s h e e t c o n ta in in g th e d e n s e s t s o u r c e d a ta h a s 2. 54 p o ly -
gons p e r s q . in . a n d 4. 02 lin e in . p e r sq . in ., w h ich m ig h t b e s u b je c tiv e ly
d e s c r ib e d a s m e d iu m -d e n s ity d a ta .
T h e s h e e t w ith th e le a s t d e n s e s o u r c e
d a ta h a s 0. 13 p o ly g o n s p e r s q . in . a n d 0 . 68 lin e in . p e r sq . in ., an d th i s
m ig h t b e s u b je c tiv e ly d e s c r ib e d a s lo w - d e n s ity d a ta .
In th e C a n a d ia n f o r m a t,
th e d a ta h a v e a ra n g e of 1. 34 to 0. 07 p o ly g o n s p e r s q . in . a n d 2. 13 to 0 . 40
lin e in . p e r s q . in .
T h e c o s ts g iv e n a r e th o s e f o r p r o c e s s in g th e l a t t e r 12
s h e e ts in th e C a n a d ia n f o r m a t.
A m o d e r a te a d d itio n a l o v e rh e a d b u rd e n is
th u s p la c e d on th e p r o c e s s , in th a t e d g e s h a v e to b e m a tc h e d b e tw e e n th e
s h e e ts th a t m a k e u p th e new d a ta s e t , b u t th e th e m a tic d a ta s e t b e in g
p r o c e s s e d r e m a in s e s s e n ti a ll y th e s a m e .
T h e c o s ts of g r a p h ic to n o n -g r a p h ic c o n v e rs io n in c lu d e a l l p r o c e s s e s b e tw e e n
th e s o u r c e d o c u m e n t m a n u s c r ip t a n d th e p ro d u c tio n of a d ig ita l r e c o r d s u ita b le
f o r c o m p u te r p r o c e s s in g .
T h is in v o lv e s th e t a s k s , d e s c r ib e d a b o v e , of
re f o r m a tti n g , im a g e s c r ib in g , p o ly g o n n u m b e rin g , d e s c r i p to r d a ta en c o d in g ,
r e f e r e n c e c o o rd in a te d ig itiz in g , a n d im a g e s c a n n in g .
T h e c o s ts f o r th i s s te p
a r e g iv e n in t e r m s of to t a l la b o u r a n d to t a l m a n - h o u rs u s e d , a n d the. n u m b e r
of m in u te s ta k e n to c o m p le te a l l th e s e fu n c tio n s p e r s q u a r e in c h of m a p s h e e t
a r e g iv e n in th e a d ja c e n t co lu m n .
It i s in t e r e s ti n g to n o te th a t th e to t a l n u m -
b e r of m in u te s p e r s q u a r e in c h (w ith o n e e x c ep tio n ) is l e s s th a n 3, th e le v e l
re c o g n iz e d in C h a p te r 3, p. 78, a s b e in g e ffic ie n t f o r m a n u a l p r o c e s s in g . T h is
i s to b e e x p e c te d , a s th e m a n u a l t a s k s in v o lv ed a r e b a s ic a lly lo w - o r d e r
o p e r a tio n s s u c h a s tr a c in g an d n u m b e rin g , a n d n o d a ta in h e r e n t in th e f ile
s t r u c t u r e h a v e to b e m e a s u r e d o r c o m p a re d .
TEST DATA CHARACTERISTICS
T otal
line
length
(in .
Line
No.of P o ly ­ incl.
P e r i ­Sheet
etr p e r i- i n . /
poly­- gons/ m
dim ensions m e te r
sq.in.
s
q
.
in.
gons
Sq.
in
(in.)
(in .)
18 x 26
88
4 .02
1883
1190
2.54
468
PROCESSING COST SUMMARY
G raphic to
non-graphic /sq.inMin.
conversion
164
1672
1252
0 .7 5
3728
18 x 26
88
468
185
0 .40
566
1.21
38 x 44
164
1672
207
0 .1 3
1134
0.6 8
1. 76
0 . 68
0. 43
15.7
21. 1
0 . 66
0 .88
0. 29
5.5
7. 9
0. 71
1. 80
0. 59
6.1
8.5
0. 38
3. 04
0. 55
3.7
4. 4
$ 8 0 6 .4 7
0. 90
0. 68
0. 42
8. 4
10.8
$1095.84
0. 37
0. 88
0. 29
3. 1
4 .4
$ 3 3 4 .2 8
0. 37
1. 80
0.5 3
3. 2
4 .4
$ 6 2 7 .9 5
0 . 21
2.5
2. 1
3. 04
0. 53
* A ssum ing labour co sts
of $5.00 p e r hour.
A ssum ed
2. 4
2.23
as
as
data
Total
5. 4
A ssum ed
38 x 44
S ource
Data
reduction
and file
form ation
TIME & COST ANALYSIS
Data red. T o ta l
cost as
&fileform
.costas
m anual
Total T otal
* eq u iv .
T otal co s t/ co st / m anual equiv.tm
tim e *
c o s t/ poly­- line in.
sq.in gon
(m in . /
($)
($) (min./sq. in) s q . in.)
($)
2.4
below
below
0. 7
T otal extrio
M a n -h r.
Govt. of
Canada
labour cost
p e r i ­m e te r
s heet
R eform at
A tal sq.in
(No. of in.)( group prox.to
sheets)
As
2
122
900
1190
1.34
1917
2.13
pro c essed
4
217
3000
1252
0 .4 2
3781
1.2 6
2
122
900
3000
in C anadian
form at
4
217
600
0 .6 7
185
0 .21
207
0.07
1187
0.40
T a b le 5 . 3.
42. 30 hr.
$182.55
65. 75 h r.
$284.85
18. 45 h r.
$ 8 0 . 25
$102.45 20. 25 h r.
IBM 370/165
in.
cpum
g ro s s system
u tilization
co sts
24. 632 min.
$623. 92
2.4
21. 451 min.
$810. 99
1.3
4. 624 min.
$254.03
1.2
$52.3 10. 559 min.
0.4
C G IS t e s t : s u m m a r y a n d t i m e a n d c o s t a n a l y s i s .
162
163
T h e c o s ts of d a ta r e d u c tio n an d f il e f o r m a tio n (d a ta b a n k c r e a tio n ) a r e g iv e n
in th e n e x t co lu m n .
of e f f o r t in v o lv e d .
T h e cpu m in u te s g iv e a n in d ic a tio n of th e r e l a ti v e am o u n t
T h e y in c lu d e a l l cpu u tiliz a tio n f o r p h a s e s 0 to 8,
in c lu s iv e , p lu s M EC ( e r r o r c o r r e c tio n ) p r o c e d u r e s .
P e r h a p s th e c o s ts o f
g r o s s u s e of th e IB M 3 7 0 /1 6 5 s y s t e m g iv e a b e t t e r in d ic a tio n of th e le v e l of
e f f o r t.
T h e c o s ts a r e th o s e p a id to a c o m m e r c i a l d a ta c e n tr e f o r u s e o f a l l
f a c i l i t i e s r e l a t e d to th e s e s ta g e s of th e p r o c e s s in g , a n d n o t s im p ly to cp u u s e .
T h e c o m b in e d c o s ts of a l l d a ta p r o c e s s in g f r o m s o u r c e d a ta to d a ta b a n k a r e
g iv e n in th e n e x t co lu m n .
A s m e n tio n e d a b o v e , a n d d e s c r ib e d in d e ta il in
th e A p p en d ix , th e s e c o s ts in c lu d e h ig h - o r d e r te c h n iq u e s f o r h a n d lin g g r a p h ic
d a t a s u c h a s a r e a m e a s u re m e n t, li n e a r m e a s u r e m e n t, s c a l e c h a n g e , p r o j e c tio n c h a n g e , to p o lo g ic a l code a s s ig n m e n t, a n d r e s t r u c t u r i n g o f th e g r a p h ic
f ile .
T h e a n a ly s is o f th e s e c o s ts in th e n e x t t h r e e c o lu m n s sh o w s w h at m ig h t
b e in tu itiv e ly e x p e c te d .
F i r s t , th e d e n s e r th e d a ta o n th e s o u r c e m a te r i a l,
th e m o r e e f f o r t (tim e a n d co st) p e r s q u a r e in c h i s r e q u i r e d to p r o c e s s th e m .
S eco n d ly , a s f e w e r p o ly g o n s p e r s q u a r e in c h a r e e n c o u n te r e d , th e c o s t p e r
p o ly g o n r i s e s (a s b o th th e s iz e of th e p o ly g o n s , a n d th e n u m b e r o f s q u a r e
in c h e s th e y e n c o m p a s s , in c r e a s e ) .
T h ir d ly , th e c o s t p e r lin e in c h o f d a ta
p r o c e s s e d sh o w s no m a r k e d tr e n d .
(T he s a m p le i s n o t l a r g e en o u g h to show
a tr e n d w h en d if f e re n c e s a r e s m a l l . ) V a r ia tio n b e tw e e n e x a m p le s in th i s
s a m p le a r e p ro b a b ly a fu n c tio n of th e n u m b e r of e r r o r s w ith in an y o n e d a ta
s e t th a t h a d to b e c o r r e c te d , o r th e edge m a tc h in g p ro b le m s e n c o u n te re d .
P e r h a p s th e m o s t in t e r e s ti n g o b s e rv a tio n s c a n b e m a d e f r o m th e ti m e a n a ly s is .
O b v io u sly , in an y m a c h in e -a id e d d a ta p r o c e s s in g s y s t e m th a t in c u r s c o s ts ,
th e q u e s tio n a r i s e s a s to th e am o u n t of m a n u a l e f f o r t th a t co u ld h a v e b e e n
b r o u g h t to b e a r on th e s a m e t a s k s if e q u a l a m o u n ts of m o n e y h a d b e e n s p e n t
o n m e n a s o p p o s e d to m a c h in e s .
T h is i s a n e x t r e m e l y d iffic u lt q u e s tio n to
a p p ro a c h , a s s o m a n y v a r i a b le s a r e in v o lv e d a n d s o m a n y a s s u m p tio n s m u s t
b e m ade.
In a n a tte m p t to p ro v id e s o m e c o m p a r is o n , h o w e v e r, th e to t a l c o s ts
in v o lv e d w e r e c o n v e rte d to h o u r s u s in g a n a r b i t r a r y fig u r e o f $ 5 . 00 p e r h o u r
f o r la b o u r c o s ts .
(No a tte m p t w ill b e m a d e to d e fe n d th i s f ig u r e .
I t is
p r o b a b ly f r a c t io n a l ly h ig h in t e r m s of s tr a i g h t s a la r y , a n d s u b s ta n tia lly low
if la b o u r o v e rh e a d i s in c lu d e d .) T h e r e s u lt in g m a n - h o u r s a r e g iv e n a s
164
m in u te s o f la b o u r p e r s q u a r e in c h of s h e e t p r o c e s s e d .
d ir e c tl y w ith th e d a ta d e n s ity , a s m ig h t b e e x p e c te d .
T h e ra n g e v a r i e s
W ith r e g a r d to th e
C a n a d ia n f o r m a t (w ith i t s lo w e r d a ta d e n s itie s ) , th e ra n g e i s 2. 5 to 10. 8 m in
p e r s q . in . (o r 2. 1 to 8. 4 m in p e r s q . in . i f th e lo w - o r d e r m a n u a l p r o c e s s e s
in v o lv e d in th e g r a p h ic t o n o n -g ra p h ic c o n v e rs io n a r e e x tr a c te d ) ; w ith r e g a r d
t o th e h ig h e r - d e n s i ty s o u r c e d a ta th e r a n g e i s 4. 4 to 21. 1 m in p e r sq . in . (o r
3. 7 to 15. 7 m in p e r s q . in . i f th e lo w - o r d e r m a n u a l p r o c e s s e s a r e e x tr a c te d ) .
D ir e c t c o m p a r is o n b e tw e e n th e c o m p u te r p r o c e s s in g a n d m a n u a l- c o s t e q u i
v a le n t t i m e s f o r th e c o m p le te ra n g e of d a ta d e n s itie s is g iv e n in T a b le 5 .4
below .
P o ly g o n s
p e r s q . in .
2 . 54
1. 34
0 . 75
0. 42
0 . 40
0 . 21
0 . 13
0 . 07
M anual
e q u iv a l e n t
(m in . p e r s q . in .)
21. 1
10. 8
7. 9
4. 4
8. 5
4 .4
4. 4
2. 5
D a ta
d e n s ity
M e d↓iu m
L ow
L in e in s .
p e r s q . in .
4 .0 2
2 .2 3
2 .1 3
1 .2 6
1 .2 1
0 .6 8
0 .6 7
0 .4 0
M anual c o st
e q u iv a l e n t
m in . p e r s q . in .
2 1 .1
7 .9
1 0 .8
4 .4
8 .5
4 .4
4 .4
2 .5
T a b le 5. 4 . CGIS a n d m a n u a l e q u iv a le n t ti m e s f o r h a n d lin g d a ta a t
v a r io u s d e n s itie s .
A n i n t e r e s t i n g o b s e rv a tio n i s th a t th e s e tim e f ig u r e s (a ra n g e o f 2 .5 to 2 1 .1
m in p e r s q . i n . ) r e p r e s e n t th e m a n u a l- c o s t e q u iv a le n t m in u te s f o r c o m p le tio n
o f s e v e r a l h ig h - o r d e r d a ta m a n ip u la tio n p r o c e s s e s .
T h e ra n g e f o r s in g le
h i g h - o r d e r d a ta m a n ip u la tio n p r o c e s s e s d e te r m in e d f r o m th e e x a m in a tio n
of m a n u a l t a s k s in C h a p te r 3, p. 78, w a s b e tw e e n 3 an d 65 m in p e r s q . in .
I n th e s e t e r m s , a n d f r o m th i s v e r y li m it e d s a m p le , i t m ig h t b e s u g g e s te d
th a t th e m a c h in e - a id e d p r o c e s s e s w e r e s o m e w h a t m o re e f f ic ie n t th a n
m a n u a l te c h n iq u e s , e v e n w h e n th e s te p o f g ra p h ic to n o n - g r a p h ic c o n v e rs io n
i s in c lu d e d in th e c o s ts .
P e r h a p s e v e n m o r e s ig n ific a n t th a n th e c o s t f a c t o r i s th e to ta l e la p s e d ti m e
r e q u i r e d to c a r r y o u t e q u iv a le n t ta s k s .
T a b le 5. 5 sh o w s th e tim e r e q u i r e d
to c r e a te th e d a ta b a n k , a s s u m in g a c tu a l tim e f o r m a n u a l p r o c e d u r e s
165
(p lu s a n o m in a l o n e -d a y a llo w a n c e f o r m a c h in e p r o c e s s tu rn a ro u n d ),
c o m p a re d w ith th e n u m b e r of m a n -d a y s th a t co u ld b e p u rc h a s e d w ith th e
s a m e fu n d s.
D ata
d e n s ity
p e r s q . in.
Sq. in .
2. 54
0. 75
0 . 40
0. 13
468
1672
468
1672
T a b le 5. 5.
E la p s e d tim e
in CGIS
days
6.
6.
3.
3.
29
72
31
53
T o ta l CGIS
co st ex p ressed
a s m a n -d a y s
@ $5 p e r h
20. 57
27. 52
8. 29
15. 33
T o ta l r e a l
e la p s e d tim e
f o r e q u iv a le n t
ta s k
B ased on m anual
e s ti m a t e s in ch . 4,
th e s e f ig u r e s co u ld
b e m u ltip lie d b y a
f a c t o r of 1 to 6 f o r
r e a l - t i m e e s ti m a t e s
CGIS t e s t : to t a l e la p s e d ti m e an d c o s t r e q u i r e d to c r e a te
d a ta b an k .
T h e a b o v e a n a ly s is r e l a t e s to th e c r e a tio n of th e d a ta b a n k an d , a lth o u g h
s e v e r a l h ig h - o r d e r p r o c e s s e s of d a ta m a n ip u la tio n h av e b e e n a c c o m p lis h e d ,
th e r e t r i e v a l of th e d a ta h a s s t i l l to b e c a r r i e d out and p a id f o r .
T h is
r e t r i e v a l c a n , of c o u r s e , in c lu d e f u r t h e r m e a s u r e m e n t and c o m p a r is o n s
p e r f o r m e d on th e n o n - g ra p h ic s to r a g e .
B e f o re p r e s e n tin g th e s e r e t r i e v a l f i g u r e s , it i s p e r tin e n t to r e m e m b e r th a t
a b a s ic o b je c tiv e of th i s s tu d y w a s to c o m p a r e th e u tility o f n o n - g r a p h ic
s to r a g e c o m p a re d w ith th e u ti lit y of g r a p h ic s to r a g e . A c a s e co u ld b e m a d e
th a t th e o n ly c o s ts r e l e v a n t to s u c h a c o m p a r is o n w ould b e th e o n e s
p r e s e n t e d b elo w , an d th a t th e c o s ts of c r e a tin g th e n o n -g ra p h ic s to r a g e
g iv e n a b o v e sh o u ld b e r e g a r d e d a s o v e r h e a d , ju s t a s th e c o s ts f o r c r e a tin g
th e o r ig in a l g r a p h ic s to r a g e a r e g e n e r a lly c o n s id e re d to b e o v e rh e a d .
The
ti m e h a s n o t y e t c o m e , h o w e v e r, w h en d a ta g a th e rin g co m m o n ly p r o c e e d s to
th e n o n - g ra p h ic f o r m a t w ith o u t p a s s in g th ro u g h th e g ra p h ic p h a s e ; th u s i t is
s t i l l r e a s o n a b le to in c lu d e th e c o s ts f o r th e s te p f r o m g ra p h ic im a g e to d a ta
b a n k , p a r t i c u l a r l y a s s e v e r a l h ig h - o r d e r p r o c e s s e s of d a ta m a n ip u la tio n a r e
in v o lv e d in c r e a tin g th e d a ta b a n k .
H o w e v e r, i t sh o u ld b e e m p h a s iz e d th a t
d a ta b a n k c r e a tio n is a o n e - tim e e f f o r t a n d r e p r e s e n t s a n o v e rh e a d c o s t th a t
m u s t n e c e s s a r i l y b e s p r e a d o v e r a l l s u b se q u e n t o p e ra tio n s o f d a ta r e t r i e v a l ,
m u c h a s s u r v e y a n d c a r t o g r a p h ic c o s ts a r e s p r e a d o v e r a l l s u b se q u e n t
p r o c e s s e s of g ra p h ic d a ta e x tr a c tio n (if th e y a r e c o n s id e r e d a t a l l! ) .
166
S e v e r a l r e t r i e v a l o p e r a tio n s w e r e p e r f o r m e d o n th e d a ta s e t s d e s c r ib e d ab o v e .
S p e c ific a lly :
1)
L in e a r m e a s u r e m e n ts of th e p e r i m e t e r of e a c h p o ly g o n w e r e m a d e f o r
e a c h d a ta s e t.
T h e s e w e r e e x p r e s s e d a s in c h e s of lin e an d a l s o c o n -
v e r t e d to m e tr e s a t m a p s c a le .
T h e r e s u l t w a s p r in te d in a r e p o r t ,
g iv in g th e code n u m b e r of e a c h p olygon, i t s d e s c r ip tiv e d a ta , i t s s iz e
in a c r e s , a n d th e tw o le n g th s m e a s u r e d .
2)
T h e a r e a of e a c h p o ly g o n w a s m e a s u r e d a n d e x p r e s s e d in a c r e s , a n d
th e c e n tr o id o f e a c h p o ly g o n w a s d e te rm in e d a n d e x p r e s s e d in d e g r e e s
of la titu d e a n d lo n g itu d e .
T h e r e s u l t s w e r e p r in te d a s a r e p o r t , g iv in g
th e c o d e n u m b e r of e a c h p olygon, th e la titu d e a n d lo n g itu d e of it s
c e n tr o id , i t s a r e a , a n d th e p e r c e n ta g e of th e to t a l a r e a o f th e d a ta
s e t r e p r e s e n t e d b y th a t p olygon.
3)
A s u m m a r y r e p o r t w a s g e n e ra te d sh o w in g th e s u m of a c r e s of p o ly g o n s
w ith th e s a m e d e s c r i p t o r , th e n u m b e r of p o ly g o n s th a t m a d e u p th e
t o t a l , th e a v e ra g e s iz e o f e a c h p o ly g o n , a n d th e p e r c e n ta g e o f th e to t a l
d a ta s e t of e a c h d e s c r i p to r .
4)
A n o v e r la y of. d a ta s e t s of th e s a m e s iz e w a s p e r f o r m e d , th a t i s , th e
m e d iu m - d e n s ity d a ta s e t of 468 sq . in . (1 ,1 9 0 p o ly g o n s) w a s o v e r la id
o n th e l e s s d e n s e d a ta s e t of 468 s q . in . (185 p o ly g o n s). S im ila r ly ,
th e 1, 67 2 -sq . in . (1, 2 5 2 -polygon) d a ta s e t w a s o v e r la id o n th e 1, 6 7 2 -sq . in .
(2 0 7 -polygon) d a ta s e t.
In e a c h c a s e a r e p o r t w a s g e n e r a te d sh o w in g
th e s iz e in a c r e s o f th e p o ly g o n s f o r m e d b y th e o v e r la y p r o c e s s , t h e i r
lin k e d d e s c r i p t o r s , a n d th e p e r c e n ta g e of e a c h new p o ly g o n c o n ta in e d
w ith in th e l e s s d e n s e p o ly g o n s of th e o r ig i n a l d a t a s e t.
5)
G ra p h ic o u tp u t f r o m th e c o m p u te r d u p lic a tin g e a c h o f th e o r ig in a l d a ta
s e t s a n d th e o v e r l a id d a ta s e t s w a s p ro d u c e d , a s w e r e r e p o r t s li s t in g
th e p o ly g o n c o d e n u m b e r, c e n tr o id c o o r d in a te s , a n d d e s c r i p t o r d a ta
f o r e a c h p lo t.
T h e c o m m a n d s to g e n e r a te th e ab o v e r e t r i e v a l p r o c e s s e s to o k 1. 5 d a y s to
p r e p a r e , th e e la p s e d tim e f o r a l l p r o c e s s e s w a s 10 d a y s ,
a n d th e to ta l
m a n - e f f o r t w a s 11. 5 d a y s .
1. T h e t e s t r e p o r t s w e r e n o n - s ta n d a r d f o r m a ts a n d th e c o s t f o r g e n e ra tin g
th e s p e c i a l- p u r p o s e r e p o r t s i s in c lu d e d i n b o th th e m a n -d a y s o f e f f o r t an d
th e c o s t o f c o m p u te r u s e .
167
T h e d a ta r e t r i e v a l c o s ts in t e r m s of g r o s s c o m p u te r u s e a r e g iv e n in
T a b le 5 .6 .
L i n e a r m e a s u r e m e n ts
O v e r la y
S o rtin g
R e p o r t p r o g r a m d e v e lo p m e n t
R e p o r t g e n e ra tio n
V a lid a tio n r e p o r t s (DDSLT)
$697
T o ta l
T a b le 5. 6.
$ 25
287
35
250
57
43
CGIS t e s t : r e t r i e v a l c o s ts .
I t c a n b e s e e n th a t e a c h of th e r e t r i e v a l p r o c e s s e s in v o lv e s h ig h - o r d e r
m e a s u r e m e n t a n d th e e x tr a c tio n of d a ta th a t a r e in h e r e n t in th e f il e s t r u c t u r e s
of g ra p h ic s o u r c e m a te r i a l.
A s m e n tio n e d ab o v e , s e v e r a l of th e s e p r o c e s s e s
a r e a c c o m p lis h e d e n r o u te to th e d a ta b a n k .
T h e o v e r la y p r o c e s s , h o w e v e r,
i s n o t in c lu d e d in th e fo r m a tio n of th e d a ta b a n k , a n d ca n o n ly b e c a r r i e d o u t
in CGIS a f t e r th e d a t a b a n k h a s b e e n e s ta b lis h e d .
I t i s p e r h a p s i n s tr u c tiv e
to e x a m in e th e c o s t of th i s p r o c e s s in d ir e c t c o m p a r is o n w ith m a n u a l t e c h n iq u e s o p e r a tin g on g r a p h ic s o u r c e d a ta .
T h e o v e r la y , w h ic h w a s c a r r i e d o u t e ff e c tiv e ly , p r o c e s s e d a t o t a l of 2 ,1 4 0
s q . in . of d a ta .
A s s u m in g th a t 20% of th e r e p o r t - g e n e r a t in g p r o c e s s w a s
a s s o c ia te d w ith th e o v e r la y (it w a s p ro b a b ly l e s s th a n th a t, a s o v e r la y r e p o r t
i s a r o u tin e CG IS fu n c tio n ), th e n th e t o t a l c o s t in c u r r e d w a s $287 + $70 = $ 3 5 7 .
T h e e la p s e d ti m e f o r th e a c tu a l o v e r la y r u n w a s l e s s th a n 10 m in , b u t,
a s s u m in g th a t 2 d a y s w e r e n o m in a lly in v o lv e d in r e q u e s t p r o g r a m m in g a n d
r e p o r t g e n e ra tio n a s s o c ia te d w ith i t , th e o v e r l a y c o s t $357 a n d to o k 2 d a y s .
F r o m a m a n u a l o v e r la y o p e ra tio n e x a m in e d i n d e t a il in C h a p te r 3, p p . 7 5 -7 6 ,
w ith d a ta s e t s of c o m p a ra b le d e n s ity , th e ti m e r e q u i r e d f o r 2, 140 s q . in . of
o v e r la y , g e n e ra tin g e x a c tly th e s a m e r e p o r t s , w o u ld r e q u i r e a p p r o x im a te ly
200 m a n - d a y s (w hich, a t a c o s t of $ 5 .0 0 p e r h o u r , w o u ld am o u n t to $ 8 ,0 0 0 ) .
T h e to t a l c o s t of c o m p le te ly c r e a tin g th e n o n - g r a p h ic d a ta b a n k a n d p e r fo r m in g a l l th e r e t r i e v a l p r o c e d u r e s m e n tio n e d a b o v e w a s $ 3 , 607. 54, th i s
f ig u r e in c lu d in g la b o u r c o s ts an d g r o s s c o m p u te r u tiliz a tio n c o s ts .1
F r o m th i s li m it e d t e s t , it c a n b e s u g g e s te d th a t, g iv e n th e n e e d to p e r f o r m
1. O v e rh e a d c o s ts of p h y s ic a l p la n t, e q u ip m e n t o th e r th a n th e c o m p u te r,
a n d s u p e r v is o r y s ta f f a r e n o t in c lu d e d in e i t h e r th e m a n u a l o r m a c h in e - a id e d
e s ti m a t e s . O v e rh e a d c o s ts , in c lu d in g c o m p u te r a m o r tiz a tio n , a r e in c lu d e d
in th e g r o s s c o s ts of c o m p u te r u s e g iv en .
168
h ig h - o r d e r p r o c e d u r e s f o r d a ta e x tr a c tio n f r o m a g ra p h ic s o u r c e d a ta b a s e of
i r r e g u l a r p o ly g o n s, i t i s a t l e a s t a s e f fic ie n t in t e r m s o f o p e r a tin g c o s ts to
c r e a te a n o n -g r a p h ic d a ta b a n k of th e CG IS ty p e to c a r r y o ut th e o p e ra tio n s
c o n c e rn e d .
In a d d itio n , if m o re th a n one r e t r i e v a l (m e a s u re m e n t o r c o m -
p a r is o n ) of d a ta i s c o n te m p la te d f r o m th a t d a ta b a n k , th e n th e c o m p a ra b le
o p e r a tin g c o s ts a r e m a rk e d ly lo w e r.
T h e c o m p u te r - a id e d te c h n iq u e s c a n
a l s o s u b s ta n tia lly r e d u c e th e e la p s e d ti m e b e tw e e n th e r e q u e s t f o r r e t r i e v a l
an d th e d e liv e r y of th e r e s u l t s o f h i g h - o r d e r m e a s u r e m e n t a n d c o m p a r is o n
o f g r a p h ic d a ta .
So f a r , th i s c h a p te r h a s b e e n d e a lin g w ith th e c a te g o r y of s y s t e m s u s in g an
i r r e g u l a r poly g o n s to r a g e f o r m a t, w h ic h c a n b e c o n s id e r e d to b e u n d e r
d e v e lo p m e n t in th e e a r l y 1970s.
T h e r e m a in in g p a r t of th is c h a p te r w ill
d is c u s s c u r r e n t d e v e lo p m e n ts in in p u t, m a n ip u la tio n , a n d o u tp u t te c h n iq u e s
w h ic h m a in ly r e f l e c t p r o b le m s r e l a t e d to h a r d w a r e .
T h e se encom pass
d ig itiz a tio n , a u to m a tic lin e fo llo w in g , s c a n n in g , in t e r a c t iv e m a n ip u la tio n
o f th e d a ta b a s e , m a n ip u la tio n of r e m o te s e n s in g d a ta , a n d g ra p h ic o u tput
c a p a b ilitie s .
In e a c h o f th e s e a r e a s , d e v e lo p m e n ts in a c tiv e p r o g r e s s
w ill g e n e ra lly a p p ly to a l l th e c a te g o r ie s o f s y s t e m d is c u s s e d s o f a r .
C U R R E N T H A R D W A R E -R E L A T E D D E V E L O P M E N T S IN IN P U T ,
M A N IPU L A T IO N , AND O U T PU T C A P A B IL IT IE S
In p u t T e c h n iq u e s
T h e fo r e g o in g d is c u s s io n h a s n o te d th a t if d ig ita l c o m p u te r s
c o m m o n ly
a v a ila b le in 1974 a r e to b e u s e d to h a n d le g r a p h ic im a g e s , th e n a n o n - g r a p h ic
(d ig ita l) r e p r e s e n t a ti o n of th e im a g e s m u s t b e g e n e ra te d .
T h is im a g e
" d ig itiz a tio n " h a s b e e n r e c o g n iz e d a s a s te p w ith s u b s ta n tia l ti m e an d c o s ts
r e l a t e d to it.
A s m ig h t b e e x p e c te d , s e v e r a l a p p ro a c h e s to d ig itiz a tio n a r e
u n d e r d e v e lo p m e n t th a t a tte m p t to r e d u c e th e c o s t b u rd e n a n d th e in h e r e n t
c o n s tr a in ts on d e v e lo p m e n t of g e o g ra p h ic in fo r m a tio n s y s te m s .
C u r r e n t p o in t /li n e d ig itiz in g . T h e s im p l e s t f o r m of m a n u a l d ig itiz a tio n i s to
p la c e a t r a n s p a r e n t g r id o v e r th e g ra p h ic im a g e an d to r e a d b y e y e th e row
a n d c o lu m n v a lu e s of p o in ts .
A n e q u iv a le n t f o r m is th e u s e of a s e t s q u a r e
o r s i m i l a r d e v ic e to r e a d c o o r d in a te v a lu e s of a p o in t f r o m th e c o o rd in a te
169
a x is a t th e ed g e of a g iv e n s h e e t.
C u r r e n t s e m i - a u to m a tic " d ig i tiz e r s " a r e
e s s e n ti a ll y e le c tr o m e c h a n ic a l d e v ic e s th a t u s e th e s a m e a p p r o a c h e s a s th e
m a n u a l te c h n iq u e s .
A p o in t m a y b e e le c tr o m e c h a n ic a lly r e l a te d to a g r id
u n d e rly in g th e s u r f a c e of th e d ig itiz in g ta b le , o r to th e im p lie d c o o rd in a te
a x is a t th e ed g e .
T h e te c h n iq u e i s th u s e s s e n ti a ll y li m it e d to th a t of a
r e a d in g d e v ic e , in th a t th e lo c a tio n of th e p oint o r p o in ts i s s t i l l c h o s e n b y
th e o p e r a t o r w ho p o s itio n s a c u r s o r .
In m o s t of s u c h s y s t e m s , a s t r e a m of
p o in ts i s g e n e r a te d a s th e c u r s o r is m o v e d a lo n g a lin e .
Such d ig itiz in g u n its
a r e r e a s o n a b l y w e ll know n an d m a n y ty p e s a r e in u s e , f r o m th o s e w h e re th e
c u r s o r s a r e m o v e d b y h a n d w h e e ls , to th e " f r e e p e n c il
ty p e s , to th e m o r e r e c e n t B en d ix d a ta g rid .
ra n g e u s e s a s o n ic p o s itio n d e te c to r .1
v a r y f r o m $ 5 , 000 to $ 5 5 ,0 0 0 .
H a rd w a re c o s ts f o r c u r r e n t d ig i tiz e r s
T h e a v a ila b le c u r r e n t e q u ip m e n t i s fu lly
d is c u s s e d b y B o y le in " G e o g ra p h ic a l D a ta H a n d lin g "2
fu rth e r d e sc rib e d h e re .
e le c tr o m e c h a n ic a l
A n o th e r r e c e n t ad d itio n to th e
an d w ill n o t b e
I t i s , h o w e v e r, p e r t in e n t to n o te th e lim ita tio n s
o f th e c u r r e n t e q u ip m e n t, s o th a t th e p o te n tia l a d v a n ta g e s o f d ig itiz in g
s y s t e m s u n d e r d e v e lo p m e n t c a n b e u n d e rs to o d .
C u r r e n t s y s t e m s n e c e s s a r i l y r e l y on th e tr a c in g c a p a b ility of h u m a n s.
T h is
i s a lo w - o r d e r m a n u a l fu n c tio n , b u t it h a s b e e n o b s e r v e d 3 th a t th e m a x im u m
s p e e d f o r t r a c i n g w ith good to l e r a n c e li m i t s i s o n ly a b o u t 2 in . p e r m in .
T h is h a s o b v io u s c o n s tr a in ts on a l l lin e d a ta in p u t.
T h e s e c o n d d iffic u lty i s
th e p o s s i b ili ty of e r r o r in a s s ig n in g d e s c r i p to r d a ta to th e g ra p h ic im a g e .
A th i r d d iffic u lty i s , of c o u r s e , th e e r r o r s th a t m a y b e in tr o d u c e d b y th e
e q u ip m e n t it s e lf .
T h e fo u r th lim ita tio n i s th a t th e d ig itiz a tio n p r o c e s s
p ro d u c e s a " b lin d " r e c o r d , th a t i s , th e o p e r a t o r c a n n o t d ir e c tl y c o m p a r e
th e r e c o r d h e i s p r o d u c in g w ith th e s o u r c e d o c u m e n t, an d th u s e r r o r s c a n
o n ly b e d e te c te d b y s u b s e q u e n t p lo ttin g a n d e d itin g of th e r e s u l t .
The lim i-
ta tio n s of c u r r e n t e q u ip m e n t a r e g r a p h ic a lly i l l u s t r a t e d b y th e fo llo w in g
e x t r a c t f r o m th e P IO S r e p o r t .4
" T h e G e o g ra p h y D e p a r tm e n t.. . m a in ta in e d a s u b - c o n t r a c t . . . f o r
d ig itiz in g , p r e - e d i tin g a n d r e - d i g iti z in g of th e p o ly g o n d a ta . H a rd w a re
a n d o th e r p r o b le m s e x p e rie n c e d b y th e U n iv e r s ity s e r io u s ly c o m p lic a te d
th e p r o je c t s itu a tio n a n d m o re th a n d o u b le d th e e s ti m a t e d tim e r e q u ir e d .
1. T h e " g r a f / p e n " p r o d u c e d b y S cie n c e A c c e s s o r ie s C o r p ., 65 S ta tio n S t . ,
S o u th p o rt C o n n ., U . S. A . 2. T o m lin s o n , .R. F . 1972. 3. S ee tr a c in g c a p a b ility
t e s t s d e ta ile d in Ch. 3, pp. 7 1 -7 3 ,a n d d is c u s s io n of d ig itiz in g o p e r a t o r
p e r f o r m a n c e b y B o y le in T o m lin s o n , R. F . 197-2. 4. D a n g erm o n d 1971.
170
f o r d ig itiz in g th e m a p s.
" O rig in a lly th e U n iv e rs ity d ig itiz in g e q u ip m e n t b e in g u s e d w a s c o n fig u re d
f o r p u n ch e d c a r d outp u t o nly, a n d h a d b e e n s u b je c t to o n ly lig h t to m o d e r a te
w o rk lo a d s . B y th e e n d of th e f i r s t m o n th of h e a v y d ig itiz in g , s p o r a d ic
e q u ip m e n t a n o m a lie s h a d in tro d u c e d e n o rm o u s e d itin g p r o b le m s . A
m a g n e tic ta p e r e c o r d e r w a s r e q u e s t e d a n d in s ta lle d .
O
" nce o p e r a tio n a l, th e ta p e r e c o r d e d outp u t sh o w e d p o o r e r q u a lity th a n
th e p u n ch e d c a r d s . A fte r e x te n s iv e in v e s tig a tio n it w a s fo u n d th a t s i m i l a r
p ro b le m s e x p e rie n c e d b y o th e r u s e r s of th i s e q u ip m e n t h a d b e e n t r a c e d to
s e r v i c e v o lta g e v a r ia tio n . T h e r e f o r e , th e v a r io u s u n its w e r e is o la te d o n
s e p a r a t e c i r c u i t s an d v o lta g e r e g u l a t o r s in tro d u c e d . T h e s e m e a s u r e s
c o r r e c t e d p u n c h e d c a r d e r r o r s , b u t h a d l i t t l e e ffe c t on m a g n e tic ta p e
o u tp u t. N ext th e m a g n e tic ta p e a n d in t e r f a c e w a s in v e s tig a te d . B y
in s u la tin g th e u n it 's c h a s s is , p ro v id in g a n a b s o lu te g ro u n d , s h ie ld in g c a b le s ,
a n d c a re f u l tu n in g , th e m o s t s e v e r e k in d s of e r r o r s w e r e e lim in a te d a n d
e r r o r fr e q u e n c y s u b s ta n tia lly re d u c e d . O ne w e e k o f p r o d u c tio n sh o w e d a
r a t e w h ich , th o u g h m u c h lo w e r th a n o r ig in a l e s ti m a t e s , c o u ld b e a m e l io r a te d w ith i n c r e a s e d s ta ffin g . T h is p r o g r e s s , co u p led w ith th e f a v o u r a b le
a p p e a r a n c e o f th e f i r s t p lo tte d m a p s , c a u s e d .. . th e U n iv e r s ity to p r o c e e d .
" T h e f o u r th a n d fifth p r o je c t m o n th s sh o w e d r e a s o n a b le p r o g r e s s . N o ise
a p p e a r e d in o u tp u t ta p e s p e r io d ic a lly , b u t f r e q u e n t r e tu n in g o f th e r e c o r d e r
in t e r f a c e w o r k e d to a lle v ia te th e p ro b le m . In a d d itio n , a s p e c ia l c o m p u te r
p r o g r a m w a s w r itt e n to o v e r c o m e th e im p a c t of n o is e on p r o c e s s in g . A n
u n e x p e c te d f u r t h e r p ro b le m a p p e a r e d in th a t d ig i tiz e r o p e r a t o r s b e g a n to
e x h ib it a n a b ility to " o v e r d r iv e " th e r e c o r d e r . T h is " o v e r d r iv e " p r o b le m
w a s c a u s e d b y o p e r a t o r s w ho a tte m p te d to r e c o r d a g r e a t e r n u m b e r of
p o in ts th a n th e m a c h in e h a d th e c a p a b ility of s to r in g an d w r itin g o n ta p e .
T h e d ig i tiz e r a l s o sh o w e d s o m e c u m u la tiv e d r if t , b u t n o t of a s ig n if ic a n t
a m o u n t w h en th e o r ig in w a s r e g u l a r ly c h e c k e d a n d r e s e t . It w a s th o u g h t
th a t th e o p e r a t o r s w o u ld s e lf - d i s c ip li n e t h e i r a c tiv i tie s . In m a n y o c c a s io n s th i s d is c ip lin e d id n o t p r e v a i l a n d th e jo b of r e d ig itiz in g i n c r e a s e d
a s a r e s u l t . U n iv e r s ity s ta ffin g d id n o t r e a c h e x p e c te d le v e ls , b u t
i n c r e a s e d s te a d ily .
T
" h e s e c o n d b a tc h of m a p s w e r e p lo tte d d u r in g th e l a s t p a r t o f th e f if th
p r o je c t m o n th a n d th e f i r s t p a r t of th e s ix th p r o je c t m o n th . T h e y il l u s t r a t e d
th a t r e m a in in g s o u r c e s o f e r r o r s w e r e m o r e s e r io u s th a n a n tic ip a te d . O ne
of th e s tu d e n t d ig i tiz e r o p e r a t o r s w a s p ro d u c in g w o rk of p o o r q u a lity an d
in m a n y c a s e s a l l th e o p e r a t o r s w e r e p ro d u c in g d r if t. S e v e r a l o f th e o th e r
o p e r a t o r s c o n tin u e d to o v e r d r iv e th e s y s te m . C o m p u te r p r o g r a m s w e r e
m o d ifie d to h e lp c o r r e c t d r if t a n d a r ig i d q u a lity c o n tr o l p la n w a s d e s ig n e d
b u t m u c h re d ig itiz in g w a s n e e d e d . T o w a rd th e e n d of th e s ix th m o n th th e
d ig itiz in g e q u ip m e n t s u f f e r e d b re a k d o w n s . T h is b re a k d o w n n e c e s s i ta te d
e x te n s iv e r e p a i r s .
"D u rin g th e s e v e n th an d e ig h th m o n th s of d ig itiz in g it w a s fo u n d th a t th e
f in a l d ig i tiz e r r e p a i r s , in c lu d in g a f ie ld m o d ific a tio n to le n g th c i r c u it
ti m e c o n s ta n t in th e ta p e in te r f a c e , a lm o s t to t a ll y e lim in a te d n o is e an d
s h a r p ly r e d u c e d o v e rd riv in g . It w a s d e m o n s tr a te d th a t if th e eq u ip m e n t
w a s o p e r a tin g e ff e c tiv e ly to b e g in w ith th e d e la y an d e r r o r p r o b le m s
w o u ld h a v e b e e n g r e a t ly re d u c e d . "
171
It sh o u ld b e e m p h a s iz e d th a t n o t a l l d ig itiz in g e f f o r ts h av e th e s a m e p r o b le m s ,
a n d th a t th e p ro b le m s a r i s e m a in ly w h en th e v o lu m e of d a ta n e c e s s i ta te s a
p r o d u c tio n o p e r a tio n r a t h e r th a n a n e x p e rim e n ta l o p e ra tio n .
T h is a u th o r,
h o w e v e r, d o u b ts th a t an y c u r r e n t p ro d u c tio n o p e ra tio n -in v o lv in g d ig i tiz e r s
h a s r e a c h e d a n y le v e l of e ff ic ie n c y w ith o u t e x p e rie n c in g s i m i l a r d if f ic u ltie s ,
e v e n if s u c h d if fic u ltie s h a v e not b e e n r e p o r t e d .
I n te r a c ti v e p o in t/lin e d ig itiz in g .
P r o b le m s s i m i l a r to th e o n e s n o te d ab o v e
p ro m p te d th e u s e of c o m p u te rs to m o n ito r th e r e c o r d b e in g p ro d u c e d b y th e
o p e r a t o r d u r in g d ig itiz in g .
T h e a v a ila b ility in 1968 a n d m o r e r e c e n tly of
m i n i- c o m p u te r s th a t co u ld b e e c o n o m ic a lly d e d ic a te d to a d ig itiz in g p r o c e s s ,
c o u p le d w ith a c c u r a te , in e x p e n s iv e , o n - lin e d is p la y u n its u s in g ca th o d e r a y
tu b e s (C R T ), g r e a t ly a c c e n tu a te d th i s tr e n d .
In th i s in t e r a c t iv e p r o c e s s , th e c o m p u te r c h e c k s th a t th e d a ta a r e p r o p e r ly
r e c o r d e d , th a t th e d e s c r i p to r f o r m a ts u s e d b y th e o p e r a t o r a r e s e n s ib le ,
th a t th e " lin e d a ta " s e n s ib ly r e p r e s e n t a lin e of d e s ir e d r e s o lu tio n an d
a c c u r a c y , an d th a t " is la n d " o r "p o ly g o n " c l o s u r e s a r e c o m p le te d p r o p e r ly ;
i t a ls o a llo w s th e o p e r a t o r to b a c k tr a c k a n d r e c o v e r o r c o r r e c t e r r o r s a s
th e y a r e m a d e .
T h e in t e r a c t iv e d ig itiz in g a p p ro a c h is s t i l l lim ite d to th e
tr a c i n g s p e e d o f th e o p e r a t o r , b u t g r e a t l y im p r o v e s th e q u a lity o f th e r e c o r d s
p ro d u c e d a n d g o e s f a r to w a r d e lim in a tin g th e le n g th y p r o c e d u r e s o f e d itin g an d
e r r o r c o r r e c tio n n e c e s s i ta te d b y " b lin d " d ig itiz in g .
S e v e r a l s u c h in t e r a c t iv e d ig itiz in g s y s t e m s a r e u n d e r d e v e lo p m e n t.
W e ll-
know n o n e s a r e r e s id e n t in th e R o y a l C o lle g e of A r t, 1 L ondon; R o m e A ir
D e v e lo p m e n t C e n te r ,2 U. S. A . ; U n ite d S ta te s G e o lo g ic a l S u rv e y ,3 W ash in g to n ,
D. C . ; a n d th e C a n a d ia n H y d r o g ra p h ic S y s te m 4 d e v e lo p e d a t th e U n iv e r s ity of
S a s k a tc h e w a n , C an a d a.
T h is a p p ro a c h d e fin ite ly h a s m e r it, p a r t ic u l a r ly
w h en th e w o rk r e q u i r e m e n t in v o lv e s low to m e d iu m v o lu m e s o f d a ta .
N u m e ro u s f i r m s in N o rth A m e r ic a , in c lu d in g IB M , R ay th eo n , H . D e ll F o s t e r ,
S y n e rc o m T e c h n o lo g y , a n d o th e r s , h a v e a d o p te d th e a p p ro a c h f o r s y s te m s
c u r r e n t l y u n d e r d e v e lo p m e n t a n d s t i l l p r o p r ie to r y .
s u c h s y s t e m s v a r i e s f r o m $ 5 0 ,0 0 0 to $ 1 5 0 ,0 0 0 .
T he h a rd w a re co st fo r
In e a c h c a s e th e s o ftw a re
h a s b e e n d e v e lo p e d b y th e a g e n c y c o n c e rn e d an d h a s n o t b ee n im p le m e n te d
e ls e w h e r e .
1. B ic k m o re 1966, 1971, R h in d 1971. 2. D ie llo 1970, P . R . C . 1973.
3. U. S. G . S. 1969. 4 . B o y le 1.970a, 1971.
172
A n in t e r e s ti n g h y b r id v e r s io n of th i s a p p r o a c h i s u s e d in th e C O P IE R s y s t e m 1
(L o c k h eed ), w h e re a g r a p h ic im a g e i s o p tic a lly p r o je c te d o n to a C R T
s u r f a c e a n d a lig h t p e n i s u s e d to t r a c e th e im a g e in te r a c tiv e ly .
S o m ew h at
s u r p r is in g ly , a g r id b lo c k s t r u c t u r e i s d e r iv e d f r o m th e C O P IE R s y s te m f o r
e a s e of s u b s e q u e n t p r o c e s s in g in th e r e l a ti v e ly s m a l l a r e a s th a t h a v e b e e n
a tte m p te d , th o u g h th e L o c k h e e d f il e s t r u c t u r e d e s c r i b e d h a s q u ite a d e q u a te
b o u n d a ry -h a n d lin g a lg o r ith m s .
A u to m a tic lin e fo llo w in g . If a d e v ic e c o u ld b e d e v e lo p e d th a t a u to m a tic a lly
fo llo w s a lin e (an d a c c u r a te ly r e c o r d s th e p a th fo llo w ed ) a t a f a s t e r r a t e
th a n a h u m a n c a n g u id e a c u r s o r , th e n a s ig n ific a n t c o n s tr a in t o n lin e
d ig itiz in g w o u ld b e r e m o v e d .
yet w on.
T h is i s a g r a i l th a t h a s b e e n so u g h t b u t n ot
In p r a c t ic e , th e a p p ro a c h u s e d c o n c e n tr a te s on th e p r o c e d u r e s
w h e re b y th e o p e r a t o r p r e d e f in e s a lin e , m a n u a lly t r a c e s a n y " le n g th s of
c o n fu s io n " , a n d a llo w s th e lin e fo llo w e r to f i l l in th e d e ta ile d lin e d ata.
T h e G e r b e r C o m p a n y , M a s s . , U. S. A .
a n d th e U. S. G. S . , 2 W ash in g to n ,
D. C . , in d e p e n d e n tly h a v e done c o n s id e r a b le r e s e a r c h on th i s a p p ro a c h ,
b u t h a v e n o t y e t d e v e lo p e d a n a c c e p ta b le s y s te m .
T h e U n iv e r s ity of
S a s k a tc h e w a n 3 u s e s a V idicon. c a m e r a c a r r i e d on an X , Y m e c h a n is m ,
c o n n e c te d to a P D P 8 /E c o m p u te r.
1 /2 in . a lo n g e a c h lin e in tu r n .
T h e V id ic o n t r a c k s in s te p s o f about
W ith in e a c h s te p a s c a n o p e r a tio n is
c a r r i e d o u t, b u t th e f in a l output i s in lin e f o r m a n d is d ir e c tl y c o m p a ra b le
w ith o u tp u t f r o m o th e r lin e d ig i tiz e r s .
In o r d e r to m a k e th e lin e tr a c in g
o p e r a tio n c o m p le te ly a u to m a tic , th e w o rk is p r e c e d e d b y a v is u a l e x a m in a t i o n o f th e a r e a o n th e in t e r a c t iv e d is p la y C R T .
S ta r t c o o r d in a te s an d
d e s c r i p t o r s a r e th e n a llo c a te d b y th e o p e r a t o r .
S p eed s o f a p p r o x im a te ly
60 in . p e r m in ca n b e a c h ie v e d u s in g th e o p e r a tio n s of p r e - e d i tin g p lu s
a u to m a tic lin e fo llo w in g .
d e v e lo p m e n t.
$ 2 0 0 ,0 0 0 ,
T h is a p p ro a c h c a n b e s a id to b e u n d e r a c tiv e
C o s ts of h a r d w a r e a s s o c ia te d w ith i t v a r y f r o m $ 3 0 ,0 0 0 to
N o a u to m a tic lin e fo llo w in g s y s t e m i s in p ro d u c tiv e u s e in an y
g e o g ra p h ic in fo rm a tio n in 1974.
H o w e v e r, th e g e n e ra tio n o f lin e in fo rm a tio n
in 20 to 30 t i m e s l e s s tim e a n d a t m e a s u r a b ly lo w e r c o s t th a n c u r r e n t
d ig itiz in g s y s t e m s i s a p r o b a b le f u tu r e d e v e lo p m e n t.
T h e u s e f u ln e s s of
th i s a p p ro a c h w ill d ep e n d u p o n th e s p e e d w ith w h ich i t c a n b e b ro u g h t in to
1. M e r r i l l 1973.
2. P e r s o n a l c o m m u n ic a tio n , E d s o n 1973.
3. B ro w n 1970.
173
r e l ia b l e p r o d u c tio n , th e a r c h i te c tu r e of l a r g e - s c a l e c o m p u te r s , a n d t h e i r
n e e d s a n d e ffic ie n c y in h a n d lin g lin e d a ta f o r m a ts a t th a t tim e .
G iv en th e
p r e s e n t a r c h i te c tu r e , c a p a b ility , a n d file s t r u c t u r e s of c o m p u te r s , th e
a u to m a tic lin e fo llo w in g a p p ro a c h w o u ld s e e m to o ff e r e x tr e m e ly a t tr a c t iv e
a d v a n ta g e s .
S can n in g . T h e s c a n n in g a p p ro a c h e s s e n ti a ll y u s e s s o m e d e v ic e to r e c o r d a
p a tc h (o r a ll) of th e s u r f a c e of th e s o u r c e d o c u m e n t in m a c h in e - r e a d a b le
f o r m , a n d r e l i e s o n th e c o m p u te r s u b s e q u e n tly to id e n tify th e im a g e e le m e n ts
w ith in th e p a tc h th a t a r e of i n t e r e s t to th e u s e r a n d n ee d to b e r e t r ie v e d .
a p p ro a c h r e q u i r e s u n e q u iv o c a l d a ta to b e s c a n n e d .
The
T he p ro g ram s needed fo r
s u b s e q u e n t id e n tific a tio n a n d la b e llin g of lin e s e g m e n ts a r e s o p h is tic a te d ;
in a d d i tio n , a m a n u a l o r s e m i- a u to m a tic p r o c e s s m u s t b e u s e d to r e l a te
d e s c r i p t o r d a ta to th e im a g e s .
T w o v e r s io n s of th e s c a n n in g a p p ro a c h h a v e b e e n fo llo w e d .
T he f ir s t is
b a s e d o n th e w e ll-k n o w n f a c s i m il e p r in c ip le , w h e re th e s o u r c e d o cu m en t i s
p la c e d o n a d r u m a n d r o ta te d in f r o n t of th e s c a n n in g h e a d , w h ic h m o v e s
in c r e m e n t a ll y a c r o s s th e f a c e of th e d ru m .
T h e e n t ir e d o cu m en t i s s c a n n e d
an d t r a n s l a t e d in to b it s of d a ta , th e n u m b e r of b it s f o r any o n e d o cu m en t
d e p e n d in g on th e s c a n s p o t s iz e .
In th e s e c o n d v e r s io n , a s m a l l a r e a (ab o u t
2 in . x 2 i n . ) of th e s o u r c e d o c u m e n t (o r a m ic r o f il m of a l a r g e r d o cu m en t)
i s s c a n n e d w ith a f ly in g sp o t ( r a s te r ) s c a n n e r , a n d th e c o m p le te d a ta f o r
th a t a r e a a r e r e c o r d e d o n m a g n e tic ta p e .
o n ly .
T h is l a t t e r p r o c e s s ta k e s s e c o n d s
T h e d a ta a r e s u b s e q u e n tly h a n d le d in m u c h th e s a m e w a y a s th o s e
fro m a d ru m sc a n n e r.
T h e r a s t e r s c a n n in g a p p ro a c h w o u ld s e e m to b e of im m e d ia te b e n e fit.
e v e r , th e d e s ig n p ro b le m s h a v e n o t y e t b e e n o v e rc o m e .
H ow -
A fly in g sp o t s c a n
of 0. 001 in . r e s o lu t io n r e s u l t s in 1 m illio n s p o ts p e r sq . in ., o r 0. 6 b illio n
s p o ts f o r a 2 0 -in . x 3 0 -in . m a p .
A 0 . 0 1 -in . s p o t s iz e g iv e s o n ly 1 0 ,0 0 0
s p o ts p e r s q . in . o r 6 m illio n s p o ts f o r th e s a m e m a p .
T h e r e f o r e , sp o t
s iz e , s h a p e , s p a c in g , p r e c i s io n p la c e m e n t, o v e rla p , e n e rg y d is tr ib u tio n ,
a n d o th e r p a r a m e t e r s of s p o t d e s ig n m u s t b e g iv e n e x tr e m e ly c a r e f u l c o n s id e r a tio n to p ro v id e th e s y s t e m w ith e c o n o m ic s c a n n in g , p lo ttin g , p r o c e s s in g , a n d d is p la y .
P r o c e s s in g tim e p e r m a p c a n q u ic k ly b e c o m e
1. S ee d is c u s s io n b y S h a rp , p p . 6 8 7 -6 8 9 in T o m lin s o n , R. F . 1972.
174
e x c e s s iv e w ith th e c o m p u te r s in g e n e r a l u s e in 1974.
T h e d r u m s c a n n in g a p p ro a c h , tho u g h s lo w e r (b etw een 1 and 15 m in , d ep e n d in g
o n m a p s iz e ) h a s b e e n u s e d to d ig itiz e e c o n o m ic a lly s o u r c e d o c u m e n ts o f u p
to 45 in . x 45 in . in s iz e .1
A V is ic o n d r u m s c a n n e r w ith a r e s o lu t io n o f
0 . 01 in . i s u s e d f o r d o c u m e n ts of u p to 11 in . x 17 in . a t P e n n s y lv a n ia
S ta te U n iv e r s ity .2
T h e R o m e A ir D ev elo p m en t C e n te r 3 u s e s a l a r g e (45-in.
x 4 5 -in .) p r e c i s io n d r u m s c a n n e r , a s d o e s T O P O C O M (U. S. A r m y T o p o g r a p h ic C o m m an d ) in W a sh in g to n , D. C.
T h e RADC s c a n n e r s a r e in te n d e d f o r
b o th p lo ttin g a n d d ig itiz in g (in th a t o r d e r ) , a n d a r e p a r t of th e p r o p o s e d
s y s t e m of d a ta s to r a g e in g r a p h ic f o r m .
T h e T O P O C O M u n it w a s p r im a r il y
in te n d e d f o r d ig itiz a tio n , b u t u s e s a n e a r l y f o r m of d is p la y m a n ip u la tio n
s y s t e m to a id th e s o f tw a r e in jo in in g s m a l l a r e a s r e c o r d e d f r o m th e s c a n
o p e r a tio n .
T h e C a n a d a G e o g ra p h ic In fo rm a tio n S y ste m u s e s a d r u m s c a n n e r ,
a s d e s c r i b e d in th e a c c o u n t of th e CGIS g iv e n ab o v e a n d in d e ta il in th e
A p p en d ix .
T h e in p u t p r o c e d u r e s , d e s c r i p to r d a ta lin k a g e , an d s u b se q u e n t
p r o c e s s in g s te p s g iv e n in th e CGIS d e s c r ip tio n a r e ty p ic a l o f th o s e e n c o u n te re d
in th e d r u m s c a n n in g a p p ro a c h .
T h e e q u ip m e n t c o s ts f o r d r u m sc a n n in g
v a r y f r o m $ 5 0 ,0 0 0 to $ 1 8 0 ,0 0 0 .
A n in t e r e s ti n g h y b r id a p p ro a c h 4 i s u s e d b y C a ls p a n C o rp o r a tio n ( f o r m e r ly
th e C o r n e ll A e r o n a u tic a l L a b or a t o r y , C. A . L . ).
T h e in i tia l s te p f o r
d ig itiz in g b a t h y m e t r ic c h a r t s s e m i- a u to m a tic a lly is to s c a n th e c h a r t an d
p ro d u c e a d ig ita l im a g e , w h ic h i s d is p la y e d to th e o p e r a to r on a C R T .
A fte r
g e o m e tr ic r e f e r e n c in g of th e e d g e " tic k " m a r k s , a s e t of c lo s e ly s p a c e d
p a r a l l e l (tra c k ) li n e s i s a u to m a tic a lly g e n e ra te d o v e r th e im a g e .
T h e c h a rt
i s th e n r e s c a n n e d a lo n g th e t r a c k li n e s , a n d in t e r s e c ti o n s w ith th e b a th y m e tr ic c o n to u rs a r e a u to m a tic a lly d e te c te d .
N ex t, th e in fo r m a tio n o n d ep th
f o r th e in t e r s e c ti o n s i s a u to m a tic a lly a d d e d i f enough d a ta a r e a v a ila b le .
T h e o p e r a t o r m a y th e n in t e r a c t w ith th e s y s t e m to d e te c t an d a d d m is s in g
c o n to u rs , d e te c t a n d d e le te e x tr a n e o u s c o n to u rs , an d p ro v id e th e n e c e s s a r y
a d d itio n a l d a ta o n c o n to u r d ep th .
T r a c k lin e b y t r a c k lin e , th e id e n tifie d
in fo rm a tio n i s w r itt e n in to m a g n e tic ta p e s to r a g e .
T h is ty p e o f a p p r o a c h is
of c o n s id e r a b le i n t e r e s t , a s it c o m b in e s th e sw ift a s p e c ts o f s c a n n in g w ith
th e in t e r a c t iv e c a p a b ility of th e o p e r a t o r to p ro d u c e a f o r m o f a u to m a tic
1. See CG IS c o s t s u m m a r y in T a b le 5. 3, p.162, a n d in A ppendix. 2. P e r s o n a l
c o m m u n ic a tio n , W illia m s , C . M. 1973. 3. D iello 1970. 4. S o lo sk o 1973.
175
lin e fo llo w in g .
ti m e .
C o s ts of u s in g th e C a ls p a n s y s t e m a r e not a v a ila b le a t th is
S uch s y s t e m s m u s t b e c o n s id e re d to b e u n d e r d ev e lo p m en t.
I t c a n b e s e e n f r o m th e a b o v e th a t th e in h e re n t c o n s tr a in t of g ra p h ic to n o n g r a p h ic c o n v e rs io n i s re c o g n iz e d n o t o n ly f r o m a th e o r e ti c a l s ta n d p o in t,
b u t a s a p r o b le m th a t m u s t b e o v e rc o m e if s p a ti a l d a ta s y s te m s a r e to
d e v e lo p f u r th e r .
In te c h n ic a l t e r m s , it is c e r t a in l y th e m a jo r c o n s tr a in t
o n s y s t e m d e v e lo p m e n t a t p r e s e n t , alth o u g h it w o u ld a p p e a r th a t a s ig n if ic a n t
r e d u c tio n in th e c o n s tr a in t m ig h t b e r e a s o n a b ly a n tic ip a te d w ith in th e n e x t
th re e y e a rs .
D a ta B a s e M an ip u latio n T e c h n iq u e s
I n te r a c ti v e m a n ip u la tio n of s p a tia l d a ta b a s e . A s ig n ific a n t d if f e re n c e b e tw e e n
g r a p h ic a n d n o n - g r a p h ic f o r m s of s p a ti a l d a t a s to r a g e i s th a t t h e f o r m e r
a r e v is ib l e to a h u m a n an d th e l a t t e r a r e v is ib le o n ly to a c o m p u te r .
W ith g r a p h ic d a ta s to r a g e , th e s to r a g e m e d iu m i s th e d is p la y m e d iu m , s o
d a ta r e t r i e v a l c a n b e g in in s ta n tly .
a c c e s s to m a p s h e e t s .
B ro w sin g i s g r e a t ly a id e d b y t h e ra n d o m
W hen s im p le in d e x e s allow id e n tif ic a tio n o f li m it e d
s e a r c h a r e a s a n d th e a v a ila b le d a ta s e t s a r e c o n v e n ie n tly g ro u p e d , th e
m a n u a l p r o c e s s i s ra p id , e ffic ie n t, an d in e x p e n s iv e .
In c o n t r a s t, i n a n y o f
th e s y s t e m s e m p lo y in g n o n -g ra p h ic f o r m s of d a ta s to r a g e d e s c r i b e d i n th e
p r e v io u s c h a p te r s , th e c o m p u te r m u s t b e c a r e f u lly in s tr u c te d to c a r r y o u t
th e s im p l e s t of r e a d in g t a s k s , b ro w s in g is c o m p le te ly in e ffic ie n t (in v o lv in g ,
a s it d o e s , th e r e q u ir e m e n t to s p e c ify w h at m u s t b e b r o w s e d b e f o r e th e
b r o w s in g b e g in s ), a n d w h en a l l is done th e c o m p u te r o u tp u t (in g r a p h ic f o rm )
s t i l l h a s to b e r e a d b y a h u m a n .
W ith th e s e c o m m e n ts in m in d , it is in t e r e s ti n g to e x a m in e s y s t e m s u n d e r
d e v e lo p m e n t th a t b o th allow d ir e c t v is u a l e x a m in a tio n of n o n - g r a p h ic s t o r e s
of s p a t i a l d a ta v ia a ca th o d e r a y tu b e , an d o ff e r th e a b ility to b r o w s e th ro u g h
th e d a ta b a s e , s e le c t s e t s of d a ta of i n t e r e s t to th e o b s e r v e r an d , th ro u g h
th e s a m e m e d iu m (C R T ), p e r f o r m ( d ir e c t an d r e c e iv e r e s u l t s f r o m ) s o m e
m a n ip u la tio n t a s k s on th e s e le c te d d a ta .
A lth o u g h th i s in t e r a c t iv e in te r r o g a tio n of a d a ta b a s e i s n o t u n c o m m o n in
176
l a r g e n o n - s p a ti a l d a ta s e t s ,1 it h a s n o t b e e n w id e ly a d o p ted f o r la r g e - s c a l e
m a n ip u la tio n of s p a ti a l d a ta .2
P e r h a p s th e b e s t e x a m p le o f s p a tia l d a ta
s y s t e m s th a t e m p lo y th e a p p ro a c h is th e a p p r o p r i a te l y n a m e d INSIGHT3
(I n te ra c tiv e S y s te m f o r In v e s tig a tio n b y G ra p h ic s o f H y d ro lo g ic a l T r e n d s ) ,
a s y s t e m d e v e lo p e d b y R . F . P h illip s of U n id a ta , Inc., A nn A r b o r , M ichigan.
T h e INSIGHT s y s t e m u s e s a s to r a g e tu b e te r m i n a l (T e c tro n ix 4010) co n n e c te d
to a ti m e - s h a r i n g c o m p u te r (IBM 36 0 /6 7 )4 t o d is p la y th e lo c a tio n s o f a p o in t
d a ta s e t of w a te r q u a lity m o n ito r in g s ta t io n s , s u p e rim p o s e d o n a b a c k g ro u n d
o f g e o g ra p h ic f e a t u r e s .
T h ro u g h th e C R T , th e u s e r c a n m a n ip u la te th i s m ap
b a c k g ro u n d in a v a r i e t y of w a y s a n d a s k f o r a n d r e c e iv e ta b u la r a n d g ra p h ic
p r e s e n t a tio n of th e w a te r q u a lity p a r a m e t e r s th a t h a v e b e e n m e a s u r e d f o r any
of th e p o in t d a ta s ta tio n s .
T h e c a rt o g r a p h ic d a ta b a s e i s q u ite s m a l l a n d e s s e n ti a ll y fix e d (a p p ro x im a te ly
2. 2 x 106 b y te s of d a ta ).
T h e d a ta b a s e r e l a t e d to th e p o in t d a ta s e t of w a te r
q u a lity m o n ito rin g s ta tio n s i s la r g e ( c u r r e n t ly 700 x 106 b y te s) an d is
e x p a n d a b le .
S in ce th e s y s t e m is g e o g r a p h ic a lly o r ie n te d , th e u s e r 's f i r s t s te p is to s e le c t
a r e f e r e n c e m a p f r o m th e c a rto g r a p h ic d a ta b a s e .
c a r t o g r a p h ic u n it o f th e s y s te m .
T h e S tate i s th e b a s ic
T h e u s e r c a n h a v e a n y s ta t e m a p d is p la y e d ,
o r a n y g ro u p , o r a l l of th e m , an d th e n in d ic a te th e one o r th e g ro u p th a t i s of
fu rth e r in te re s t.
T h e r e s u lt in g m a p c a n b e m o d ifie d , b y s h rin k in g o r
e x p a n d in g th e d is p la y s c a l e , b y zo o m in g o r p an n in g , w ith r e s p e c t to th e
o r ig i n a l d a ta , o r b y d e s ig n a tin g a c e r t a i n p o ly g o n a l p o rtio n (a co u n ty , f o r
e x a m p le ).
A d d itio n a l g e o g ra p h ic a l f e a t u r e s s u c h a s county b o u n d a rie s ,
r i v e r t r a c e s , la k e o u tlin e s , a n d m u n ic ip a l b o u n d a rie s c a n b e s e le c tiv e ly
a d d e d a t th i s p o in t b y r e q u e s tin g th a t th e y b e o v e r la id on th e s ta t e o u tlin e s .
T h is i s e s s e n ti a ll y a b ro w s in g p r o c e s s th ro u g h a s e t of m a p s.
T h e s c a le
c a n b e e n la r g e d u n til th e lim it of th e o r ig i n a l d ig itiz e d d a ta i s r e a c h e d .
1. A s, f o r e x a m p le , a t a i r lin e ti c k e t c o u n te rs in N o rth A m e r ic a a n d E u ro p e .
2. I t h a s , h o w e v e r, b e e n a d o p te d f o r a v a r i e ty of m i lit a r y a p p lic a tio n s , a n d in
c o m m e r c e , f o r o n - lin e m a n ip u la tio n of s p a ti a l d a ta f o r a i r t r a f f i c c o n tro l.
3. P h ill ip s , R . L .1972, U n id a ta , In c . 1973. 4. T h is i s a d uplex cpu c o n fig u ra tio n
w ith 2, 700 p a g e s of v ir t u a l m e m o ry (4K b y te s /p a g e ) a v a ila b le o n th r e e p ag in g
d r u m s . T h e c o m m u n ic a tio n s in t e r f a c e i s a d a ta c o n c e n tra to r b a s e d on a P D P 8 /E
a n d a s s o c ia te d m u ltip le x in g an d p o r t s e le c ti o n h a r d w a r e . C o n v en tio n al
s u p p o rt r o u tin e s w ith te le ty p e d e v ic e s a r e u s e d f o r g ra p h ic t e r m in a l
o p e r a tio n s .
177
S e v e r a l a d d itio n a l m a n ip u la tio n f e a t u r e s a r e p o s s ib le on th i s d a ta b a s e .
A reas
c a n b e m e a s u r e d b y tr a c in g t h e i r o u tlin e w ith th e c u r s o r o n th e C R T.
S im ila r ly , lin e s ca n b e m e a s u r e d b y m o v in g th e c u r s o r a lo n g t h e i r le n g th .
L o n g itu d e a n d la titu d e of an y c u r s o r p o s itio n c a n b e c a lc u la te d .
of th e s e c a lc u la tio n s a r e show n on th e s c r e e n .
T h e r e s u lt s
T h e m o s t im p o r ta n t f a c ility
o f th e s y s t e m i s , h o w e v e r, th e c o n n e c tio n w ith th e h y d ro g ra p h ic d a ta .
The
c a rt o g r a p h ic b a s e a c ts a s a n in d e x to th e v a s t s t o r e of w a te r q u a lity d ata.
T h e p o in t d a ta r e p r e s e n t in g th e p o s itio n s o f th e w a te r q u a lity s ta tio n s a r e
d is p la y e d o n th e c a rto g r a p h ic d a ta b a s e .
of s ta tio n s is s e le c te d .
F r o m th is b a s e , th e d e s ir e d s e t
A l i s t of d a ta a v a ila b le a t e a c h of th e s e le c te d s ta tio n s
c a n th e n b e d is p la y e d .
A fte r b r o w s in g th ro u g h th e l i s t , th e o b s e r v e r s e le c ts
th e d e s ir e d v a r i a b le s .
A c o n v e n tio n a l g ra p h sh o w in g th e d is tr ib u tio n o f th e
v a r i a b le s o v e r tim e a t th e s e le c te d s ta tio n s c a n th e n b e g e n e ra te d ; e q u a lly ,
th e d a ta c a n b e l i s t e d in ta b u la r fa s h io n o r , p e r h a p s m o re in te r e s tin g ly ,
th e w a te r d a ta a n d c a r to g r a p h ic d a ta b a s e c a n b e c o m b in e d a t th i s p o in t and
a th r e e - d im e n s i o n a l p e r p e c tiv e d is p la y of th e s ta t io n s , th e c o u n try
s u r r o u n d in g th e m , an d th e m e a s u r e m e n ts of th e s p e c ifie d p a r a m e te r s ca n
b e d is p la y e d a s a v e r t i c a l b a r g ra p h .
G e n e r a l c o s t f ig u r e s a r e n o t a v a ila b le , b u t d a ta h av e b e e n g a th e r e d f r o m
o p e r a tio n in th e U n iv e rs ity of M ich ig an c o m p u te r.
W hen th a t s y s t e m is
u s e d , o n e is c h a rg e d m a in ly f o r : (1) c o n n e c t ti m e , a t $3 p e r h o u r; (2) cpu
t i m e , a t $ 4 . 73 p e r m in ; an d (3) a c tu a l v ir t u a l m e m o ry , a t $ 2 . 85 p e r p a g e h o u r.
F o r a ty p ic a l 1 -h o u r s e s s i o n w ith IN SIG H T, an d 20 to 30 r e t r i e v a l s
f o r ab o u t 20 s ta t io n s , th e c o s t r u n s b e tw e e n $15
T h e lim ita tio n s o f th e s y s t e m a r e o b v io u s.
an d $20.
I t i s a p o in t d a ta s y s t e m o f th e
G RDSR ty p e , em b e d d e d in a s im p l is tic c a rto g r a p h ic d a ta s e t.
T h e s im p l i-
c ity of th e c a rto g r a p h ic d a ta s e t is id e a l f o r th e in d e x in g p u r p o s e s f o r w h ich
i t i s u s e d , an d no p r e c i s io n i s a tte m p te d o r n e e d e d .
T h e s p a ti a l m a n ip u la -
tio n fu n c tio n s ( a r e a m e a s u r e m e n t a n d c o o rd in a te p o in t m e a s u re m e n t) a r e
e s s e n ti a ll y m a n u a lly t r a c e d , an d th e o p e r a t o r w o r k s in a r e la tiv e ly
e x p e n siv e (c o m p u te r-lin k e d ) e n v iro n m e n t.
N e v e r th e le s s , th e a b ility to
r e a d e ff e c tiv e ly an d b ro w s e th ro u g h n o n - g ra p h ic s to r a g e a t th e s e v o lu m e
le v e ls i s c l e a r ly in d ic a te d , a s is th e a b ility to g a in r a p id a c c e s s to hu g e
178
a m o u n ts of d a ta a n d m a n ip u la te s e le c te d s u b s e ts .
T h is p r o c e s s w o u ld s e e m
to b e a fu n d a m e n ta l r e q u i r e m e n t if l a r g e - s c a l e n o n -g ra p h ic s t o r e s o f s p a tia l
d a ta a r e to b e of w id e u s e in th e f u tu r e .
M a n ip u la tio n of E R T S n u m e r ic a lly coded im a g e s .
R e m o te s e n s in g is a
s u r v e y te c h n iq u e th a t c a n a n d d o e s p ro d u c e la r g e q u a n titie s of s p a ti a l d a ta in
n o n -g r a p h ic f o r m a s a p r im a r y p ro d u c t.
T h e E R T S -A s a te lli te , f o r
e x a m p le , p r o d u c e s a p p ro x im a te ly 9, 212 o r ig in a l n u m e r ic a l im a g e s o f 1, 316
s c e n e s o v e r th e U. S. A. a lo n e , e a c h w eek .
r e t a in e d in n u m e r ic a l f o r m .
O f th e s e , b e tw e e n 1% a n d 5% a r e
E a c h s u c h im a g e , h o w e v e r, c o n ta in s a p p r o x i-
m a te ly 16 m illio n c e l l s , e a c h co d e d to 64 g r e y le v e ls in 6 b it s ; in o th e r w o r d s ,
e a c h im a g e p r o d u c e s 96 m illio n b i t s of n u m e r ic a l in fo rm a tio n .
E a c h w eek
a p p ro x im a te ly 300 n u m e r ic a l im a g e s a r e r e c o r d e d on a p p r o x im a te ly 870 c o m p u te r - c o m p a tib le m a g n e tic ta p e s .
T h e o r ig in a l im a g e d a ta p r o d u c e d c a n , of
c o u r s e , b e t r a n s l a t e d in to g ra p h ic f o r m b y a v a r i e ty of p r o c e s s e s .
The
r e s u lt in g p ic tu r e s c a n b e v is u a lly in t e r p r e te d an d th e r e s u l t s of s u c h i n t e r p r e t a ti o n c a n b e c o n v e rte d to d a ta b a n k f o r m a ts u s in g a n y o f th e te c h n iq u e s
d e s c r ib e d a b o v e .
A c o n s id e r a b le c h a lle n g e , h o w e v e r, e x i s t s in th e p o s s ib ility o f u s in g th e
c o m p u te r to m a n ip u la te a n d c o n v e rt d ir e c tl y th e 1% to 5% of im a g e s le f t in
th e ra w n u m e r ic a l d a ta f o r m a t, in to a u s e f u l d a ta b a n k f o r m a t.
T h e m an y
v a r i a b le s a s s o c ia te d w ith th i s t a s k a r e th o ro u g h ly d o cu m en ted b y S te in e r
in " G e o g ra p h ic a l D a ta H a n d lin g " . 1 T h e d a ta re d u c tio n s te p s in c lu d e im a g e
p r o c e s s in g , p a t t e r n r e c o g n itio n , s t a t i s t i c a l r e la tio n s h ip s to n o n - o b s e r v a b le s ,
d e s c r i p tiv e u n it a s s ig n m e n t, ch an g e d e te c tio n , a n d g e o m e tr ic b a s e
r e c o n s t r u c tio n .
T h e r e s u lt in g p ro d u c ts w o u ld b e a m e n a b le to en c o d in g f o r
d a ta b a n k u s e o r to a f u tu r e f o r m of p ic to r ia l in fo rm a tio n s y s te m .
I t i s o u ts id e th e s c o p e o f th i s th e s i s to e x p lo re th e d a ta te c h n iq u e s in v o lv ed
in p ic t o r i a l d a ta r e d u c tio n .
T h e y do, h o w e v e r, r e p r e s e n t an e x te n s io n o f th e
c o n v e n tio n a l n o n - g r a p h ic p r o c e s s in g te c h n iq u e s c o v e re d in th i s th e s i s an d
w ill f o r m a b r id g e b e tw e e n th e la r g e m a s s e s of n u m e r ic a lly c o d e d p ic tu r e
in fo rm a tio n now b e c o m in g a v a ila b le an d g e o g ra p h ic in f o rm a tio n s y s te m s th a t
w ill b e d e v e lo p e d h e r e a f t e r .
1. T om lin s o n , R . F . 1972.
A t th e m o m e n t, h o w e v e r, th e te c h n iq u e s
179
d e v is e d f o r n u m e r ic a l d a ta re d u c tio n do not allow a c c u r a te th e m a tic in f o r m a tio n to b e e x t r a c te d f r o m th e n u m e r ic a l p ic to r ia l d a ta b a s e , e x c e p t in c lo s e ly
c o n tr o lle d t e s t s itu a tio n s o r f o r g r o s s th e m a tic o b s e r v a tio n s .
In a d d itio n ,
th e g e o m e tr ic r e s ti tu ti o n o f th e p ic t o r i a l im a g e s d e g r a d e s t h e i r a l r e a d y low
re s o lu tio n a n d f u r t h e r in v a lid a te s th e m a tic id e n tific a tio n p r o c e s s e s .
In th e m a in , it c a n b e s a id th a t th i s a p p ro a c h to m a n ip u la tio n o f ra w n u m e r ic a l
s p a ti a l d a ta d o e s n o t a d d a n y s ig n ific a n t a m o u n t of d a ta to g e o g ra p h ic in f o r m a tio n s y s t e m s , b u t th a t it i s an a p p r o a c h w h ich m u s t b e fo llo w e d f u r t h e r a s
s e n s o r s a r e d e s ig n e d to p ro d u c e m o r e p r e c i s e , h ig h - r e s o l u tio n d a ta an d a s
c o m p u te r c o n fig u ra tio n s a r e d e v e lo p e d th a t a r e a m e n a b le to s u c h p r o c e s s in g .
O utput D e v ic e s
O u tp u t d e v ic e s a r e th o s e th a t c o n v e rt n o n - g ra p h ic d a ta to a g r a p h ic f o r m a t.
T h e y r a n g e f r o m lin e p r i n t e r s of a lp h a n u m e ric s y m b o ls (o r s p e c i a l s y m b o ls ),
th ro u g h s y m b o l a n d lin e d ra f tin g m a c h in e s ( p lo tte r s ) , to c a th o d e r a y tu b e s
of v a r i o u s k in d s .
T h e r e i s a w id e r a n g e of "designs a n d c a p a b ilitie s , c o s ts
a n d c o n v e n ie n c e s in th e s e m a c h in e s .
A f u ll d e s c r i p tio n of th e e q u ip m e n t
h a s b e e n p ro v id e d b y R . B o y le 1 in " G e o g ra p h ic a l D a ta H a n d lin g " .
The
s p e c t r u m of c a p a b ilitie s f o r p ro d u c in g m a p s w ith th e s e d e v ic e s w a s th o ro u g h ly
d e m o n s tr a te d b y D. E d s o n 1 in th e s a m e v o lu m e .
T h e ir r e v ie w s w ill n o t b e
r e p e a te d h e r e ; it is s im p ly p e r tin e n t to n o te th a t th e d e v ic e s p r e s e n t no
c o n s tr a in t on c u r r e n t a b ility to h a n d le s p a tia l d a ta .
A ny n o n - g r a p h ic im a g e
c a n b e r e a d i ly a n d e c o n o m ic a lly tr a n s f o r m e d to a g r a p h ic im a g e , to an y
d e g r e e of p r e c i s io n a n d r e s o lu t io n in h e re n t in th e n o n - g ra p h ic d a ta .
E ach
y e a r s u c h s y s t e m s d e v e lo p i n c r e a s e d s p e e d of o p e ra tio n , im p r o v e d r e l ia b i lit y ,
a n d lo w e r u n it c o s t.
T h i s , a t l e a s t , i s th e s itu a tio n in 1974.
P e r h a p s w ith
th e e x c e p tio n of C R T s to r a g e tu b e s (w hich m ig h t c o n v e n ie n tly b e s o m e w h a t
la r g e r ) , no s p a ti a l d a ta b a s e h a s g r a p h ic f o r m a ts th a t ca n n o t b e d is p la y e d
w ith in th e l i m i t s of e x is tin g d e v ic e s .
O ne ca n , h o w e v e r, v is u a l iz e f u tu r e
d e v e lo p m e n ts in s p a ti a l d a ta s to r a g e (s u c h a s h o lo g ra p h ic m e m o r ie s , o r
p ic tu r e - p r o c e s s in g c o m p u te rs ) th a t w ould e x c e e d th e c a p a b ility of e x is tin g
o u tp u t h a r d w a r e .
T h is s ta g e h a s n o t y e t b e e n r e a c h e d , a n d it i s r e a s o n a b le
to s a y th a t th e c u r r e n t o u tp u t e q u ip m e n t an d th e te c h n iq u e s e m p lo y e d a r e
a s good a s o r b e t t e r th a n c u r r e n t c a p a b ility f o r s p a ti a l d a ta h a n d lin g .
1. T o m lin s o n , R. F . 1972.
180
M U L T I-F O R M A T SYSTEM S
A m u l ti- f o r m a t g e o g ra p h ic in f o rm a tio n s y s t e m i s one th a t a tte m p ts to h a n d le
m o r e th a n one f o r m a t of n o n - g ra p h ic s p a ti a l d a ta .
T h e r e a r e tw o a s p e c t s to
th i s c a p a b ility , e i th e r o r b o th of w h ich m a y b e p r e s e n t in a m u lti- f o r m a t
s y s te m .
T h e f i r s t is th e a b ility to a c c e p t and s t o r e d a ta of d if f e re n t f o r m a ts
in th e b a s i c file s t r u c t u r e of th e s y s te m .
T h is p r o c e s s i s c l e a r ly d if f e re n t
f r o m th a t of c o n v e rtin g d iffe re n t s o u r c e d a ta f o r m a ts to a s in g le f o r m a t f o r
s u b s e q u e n t n o n - g ra p h ic s to r a g e .
T h e s e c o n d a s p e c t i s th e a b ility to ch a n g e
th e d a ta s t o r e d in s in g le o r m u ltip le f o r m a ts in th e file s t r u c t u r e o f th e
s y s t e m to a l te r n a t iv e f o r m a ts f o r u s e in su b se q u e n t p r o c e d u r e s o f d a ta
m a n ip u la tio n o r d is p la y .
T h e s e tw o a s p e c ts w ill b e c o n s id e r e d s e p a r a t e ly .
T h e a b ility to ch a n g e d a ta s to r e d in a s in g le f o r m a t to a lte r n a tiv e f o r m a ts i s
in c r e a s in g ly c o m m o n in g e o g ra p h ic in fo rm a tio n s y s te m s .
b e h in d s u c h t r a n s f o r m a tio n s a r e v a r ie d .
The p u rp o ses
A ty p ic a l u s e i s to r e d u c e th e v o lu m e
o f d a ta th a t m u s t b e h a n d le d in s u b se q u e n t d a ta m a n ip u la tio n s , o r s im p ly to
p ro v id e th e d a ta in a f o r m a t th a t is a m e n a b le to c e r t a in ty p e s o f m a n ip u la tio n .
A n o th e r u s e i s to allow c o m p a ris o n w ith d a ta s e t s th a t a r e a v a ila b le in th e
a l te r n a t iv e f o r m a t.
A s w ith th e tr a n s i tio n f r o m th e f o r m a t of r e a l - w o r l d d a ta
e le m e n ts to th e s to r a g e f o r m a t, a ch a n g e m a y im p ly s o m e l o s s o f in fo rm a tio n .
S im ila r ly , th e l o s s of in fo rm a tio n te n d s to d e c r e a s e a s th e s iz e o f th e s to r a g e
e le m e n t d e c r e a s e s in r e l a ti o n to th e s iz e of th e o utput e le m e n ts , a s show n
in F ig . 5. 15.
S iz e of
s to r a g e e le m e n t
S ize o f o u tp u t e le m e n t
F ig . 5. 15.
In fo rm a tio n l o s s in r e l a ti o n to s iz e s of s to r a g e an d o u tp u t
e le m e n ts .
V e ry s m a l l g r id c e l l s , f o r e x a m p le , m a y b e g ro u p e d in to v e r y la r g e i r r e g u l a r
p o ly g o n s w ith a m in im a l in fo rm a tio n l o s s (and w ith an a tte n d a n t r e d u c tio n in
d a ta v o lu m e ).
A p o ly g o n r e p r e s e n t e d b y i t s c e n tro id c o o r d in a te , o n th e o th e r
181
h a n d , m a y in c u r a s u b s t a n ti a l in fo r m a tio n l o s s (alth o u g h th e in fo rm a tio n
lo s s m a y n o t b e of c o n c e r n to a p a r t i c u l a r u s e r , an d th e s ig n ific a n t r e d u c tio n
in d a ta v o lu m e f o r s o m e m a n ip u la tio n s m a y b e a t tr a c t iv e ) .
T h e fo llo w in g
d ia g r a m (F ig . 5. 1 6 .), w h ic h c lo s e ly fo llo w s F ig . 4. 7 b u t w h ich now r e l a t e s
s to r a g e f o r m a t to o u tp u t f o r m a t, sh o w s ty p ic a l tr a n s f o r m a tio n s w h ich a r e
c u r r e n t ly c a r r i e d out in v a r i o u s s y s t e m s .
S to ra g e f o r m a t
GRID
P O IN T
LIN E
PO L Y G O N
S m all L a rg e
GRDSR
G RID
O p tim u m
(for
m a n ip u la tio n
o r d isp la y )
3
PIOS
P O IN T
Same
SYMAP
L IN E
3
SYMAP
POLYG O N
F ig . 5 .1 6 .
CGIS
3
O utput f o r m a t
3
Same
O p tim u m
3
DIME, FRIS
Optimum
3
DIME
GRDSR
O p tim u m
3
3
T r a n s f o r m a tio n s b e tw e e n s to r a g e a n d o u tp u t f o r m a ts
u n d e r ta k e n b y ty p ic a l s y s te m s .
T h e a d v a n ta g e s o f h a n d lin g r e d u c e d v o lu m e s of d a ta (fo r e x a m p le , p o ly g o n s
r e p r e s e n t e d a s c e n tr o id s ) c a n b e r e a d i ly u n d e r s to o d .
S im ila r ly , th e
d e s ir a b ili ty (if n o t th e v a lid ity ) of ch a n g in g f o r m a ts to allow c o m p a r is o n w ith
o th e r d a ta s e t s c a n b e a p p r e c ia te d .
T h e v a lu e of ch a n g in g n o n - g r a p h ic
s to r a g e f o r m a ts to f a c i li ta te s p e c if ic s p a ti a l d a ta m a n ip u la tio n s i s i l l u s
t r a t e d in th e fo llo w in g e x a m p le s .
G iven a s u r f a c e d e s c r i b e d b y d a ta e le m e n ts in th e f o r m o f i r r e g u l a r p o ly g o n s
w h o se b o u n d a rie s a r e is o lin e s , an d g iv e n th e n e e d to d e te r m in e s u r f a c e s lo p e s ,
i t i s th e o r e ti c a ll y p o s s ib le to c a lc u la te th e s lo p e d a ta d ir e c tl y f r o m th e
is o li n e s , b u t o n ly w ith a r e l a ti v e ly c o m p le x a l g o r ith m w h ich i s th u s e x p e n siv e
to u se.
T h e p o ly g o n f o r m a t c a n , h o w e v e r, b e ch a n g ed to a s m a l l g r id
f o r m a t f r o m w h ich s lo p e d e te r m in a tio n is s im p ly d e r iv e d b y c o m p a rin g th e
e le v a tio n a t a g iv e n c e ll w ith th a t of th e s u rro u n d in g c e lls .
D iv isio n b y th e
182
c o n s ta n t s c a l e d d is ta n c e b e tw e e n ro w s an d c o lu m n s g iv e s th e s lo p e g ra d ie n t.
T h e c e ll s iz e c h o s e n i s , of c o u r s e , s ig n ific a n t, a s th e c a lc u la tio n can n o t
ta k e in to a c c o u n t i r r e g u l a r i t i e s th a t m a y e x is t w ith in th e g r id c e ll.
If th e
c e lls a r e r e l a t i v e l y s m a l l, f o r th e m a jo r ity of d e c is io n -m a k in g p u r p o s e s
th e r e s u l t s o b ta in e d b y th i s a p p r o a c h to s lo p e c a lc u la tio n a r e d ir e c tly
c o m p a ra b le to r e s u l t s f r o m th e is o lin e in t e r p r e ta tio n a lg o r ith m , an d th e y
a r e s u b s t a n ti a ll y e a s i e r to a c q u ir e .
S im ila r ly , v a l u e s of i r r e g u l a r l y d is tr i b u te d p o in t d a ta c a n b e u s e d to c a l c u la te r e l a t e d v a lu e s f o r a n o v e r la y of s m a l l g r id s q u a r e s (as o p p o s e d to
g ro u p in g p o in ts w ith in g r id s q u a r e s ) .
T h e r e s u lt in g a r r a y ca n b e u s e d in
d a ta m a n ip u la tio n s s u c h a s d iffu s io n a n a ly s is w ith m u c h g r e a t e r e ffic ie n c y
th a n d ir e c t u s e of th e p o in t d a ta s e t (though e r r o r m a y b e in tro d u c e d b y th e
a s s u m p tio n s in h e r e n t in th e p o in t- to - g r id tr a n s f o r m a tio n p r o c e s s , a n d m ay
a r i s e f r o m th e o r ig in a l d is tr ib u tio n of th e p o in ts).
T h e e x a m p le s g iv e n a b o v e m ig h t in d ic a te th a t a g r id f o r m a t i s a d e s ir a b le
p r i m a r y f o r m a t f o r d a ta .
In s o m e c i r c u m s ta n c e s it i s .
It i s a lig n e d to
m u c h c o m p u te r a r c h i te c tu r e ( p a r t ic u la r ly th a t of th e e a r l y c o m p u te r s ) , and
e v e n to s o m e c o m p u te r la n g u a g e s (F O R T R A N , f o r e x a m p le , h a s i t s r o o ts
in m a t r i x m e th o d o lo g y ).
H o w e v er, it m u s t b e s t r e s s e d th a t th e f o r m a t
c h a n g e i s , to a g r e a t e x te n t, i r r e v e r s i b l e .
In th e e x a m p le g iv e n a b o v e , it
i s n o t p o s s i b le to r e c a lc u l a te th e lo c a tio n s of th e o r ig in a l p o in t d a ta , o r
to t r a c e th e o r ig in a l p o ly g o n a l b o u n d a r ie s a c c u r a te ly f r o m th e g r id v a lu e s .
T h e a b i lit y to c h a n g e to a g r id f o r m a t f o r s o m e m a n ip u la tio n s i s c l e a r ly
d e s ir a b le .
I t s v a lu e a s a u n im o d a l s to r a g e f o r m a t h a s to b e c o n s id e r e d
w ith due c a u tio n a n d w ith a tte n tio n to o v e r a l l r e q u i r e m e n t s f o r d a ta
m a n ip u la tio n .
In th e s a m e m a n n e r th a t p o in t a n d p o ly g o n d a ta c a n b e r e l a t e d t o g r id s , so
d a ta f r o m a l te r n a t iv e f o r m a ts c a n b e r e l a te d to lin e s e g m e n ts .
J u s t a s th e
e x a m p le g iv e n ab o v e of t r a n s f o r m in g p o in t d a ta to g r id s im p lie d th e a s s ig n m e n t of a w e ig h te d v a lu e to a g r id c e ll, s o c a n th e d is ta n c e - o f - p o in t d a ta
a t t r i b u t e s b e u s e d a s a w e ig h tin g f a c t o r in a s s ig n in g v a lu e s to lin e se g m e n t
d a ta .
T h is a p p ro a c h c a n , f o r e x a m p le , in t e r n a l ly s im p lif y th e a n a ly s is of
c o r r i d o r s th ro u g h lin e n e tw o rk s .
A r e c e n t s tu d y to lo c a te tr a n s m is s i o n
183
li n e s c a r r i e d o u t f o r th e A riz o n a P u b lic S e rv ic e 1 w e ig h te d d a ta ite m s f o r
r e l a t i v e c o m p a tib ility w ith tr a n s m is s i o n lin e r o u te s , c o n s id e r in g su ch
f a c t o r s a s d is ta n c e f r o m h is to r i c s ite s (point d a ta ), d is ta n c e o v e r b a d
g ro u n d c o n d itio n s (polygon d a ta ), a n d in t e r s e c ti o n s w ith r a i l r o a d s (o th e r
lin e s e g m e n t d a ta ).
T h e s tu d y d e riv e d v a lu e s f o r e a c h lin e s e g m e n t b a s e d
o n th is t r a n s f e r of v a lu e f r o m o n e d a ta f o r m a t to a n o th e r.
T h e r e s u ltin g
a n a ly s is f o r n e tw o rk o p tim iz a tio n w a s a s tr a i g h tf o r w a r d li n e a r p r o c e d u r e .
J u s t a s in th e c a s e of g r id c e lls , a llo c a tio n of th e (w eighted) v a lu e s to th e
lin e s e g m e n ts i s i r r e v e r s i b l e .
It is n o t p o s s ib le to r e c r e a t e th e s o u r c e
d a ta f o r m a t f r o m th e new f o r m a t.
H o w e v e r, th e b e n e fit of th e c a p a b ility
f o r f o r m a t ch a n g e w ith in s y s te m s ca n b e a p p r e c ia te d .
A s w a s n o te d in C h a p te r 4 , p p . 9 6 -9 7 , a t th i s e a r l y s ta g e o f d ev e lo p m en t of
c o m p u te r - a i d e d s y s t e m s f o r h a n d lin g s p a ti a l d a ta
t h e r e h a s b e e n a te n d e n c y
t o a v o id th e c o m p lic a tio n s of c r o s s - f o r m a t lin k a g e s th a t w o u ld b e r e q u ir e d
b y m u l ti- f o r m a t p r i m a r y s to r a g e ; h e n c e , th e file s t r u c t u r e s o f s y s te m s
h a v e g e n e ra lly b e e n d e v e lo p e d a ro u n d a s in g le f o r m a t of s p a ti a l d ata.
p r e s s u r e s to c h a n g e th i s s ta t e of a f f a i r s a r e e a s y to u n d e r s ta n d .
The
The r e a l
w o r ld c a n b e m o re a c c u r a te ly d e s c r ib e d if a m ix tu re of d a ta f o r m a ts (p o in ts,
l i n e s , a n d a r e a s ) i s e m p lo y e d , a n d e x p la n a tio n s of th e in t e r a c t io n o f r e a l w o r ld p h e n o m e n a f r e q u e n tly in v o lv e r e a l - w o r l d d a ta e le m e n ts th a t h ave
d if f e re n t o p tim a l s to r a g e f o r m a ts .
T h e d e s ig n of s e v e r a l s y s t e m s o b v io u sly
r e f l e c t s a r e s p o n s e to th e s e p r e s s u r e s .
T h e F R IS s y s t e m f r o m
S w eden, now b e in g f u r t h e r d ev e lo p ed b y th e
N O R D P L A N 2 a g e n c y , h a s a l t e r e d i t s p r im a r y p o in t f il e s t r u c t u r e s o th a t
lin e n e tw o rk s c a n b e id e n tif ie d a n d m a n ip u la te d .
T h e po in t d a ta a p p ro a c h
i s s t i l l u s e d to lo c a te th e b a s ic s t a t i s t i c a l r e c o r d s .
T h e p o in t-n e tw o rk
lin k a g e s h a v e a llo w e d th e d e v e lo p m e n t of q u ite s o p h is tic a te d m o d e ls f o r
r e s o u r c e a llo c a tio n .
S im p le f ix e d - s o u r c e d is tr i c ti n g p r o b le m s , s u c h a s
a llo c a tio n of s c h o o l b o u n d a r ie s an d t r a v e l- to - w o r k c a lc u la tio n s , a r e now
b e in g c a r r i e d o u t in a d d itio n to m a n ip u la tio n s o f p o in t d ata.
T h e D IM E3 s y s t e m , alth o u g h p r im a r il y a n e x a m p le of a lin e n e tw o rk s y s te m ,
i s a l s o a n e x a m p le of a m u l ti- f o r m a t s y s t e m th a t a c c e p ts a r e a l an d lin e d a ta
1. D a n g e rm o n d 1973. 2. P e r s o n a l c o m m u n ic a tio n , S alo m o n sso n 1973.
3. C o rb e tt a n d F a r n s w o r t h 1971.
184
in to i t s p r i m a r y s to r a g e f o r m a t (h en ce th e w o rd "D u al" in i t s a c ro n y m ).
T h e s y s t e m s t r e s s e s i t s c a p a b ility f o r h an d lin g lin e n e tw o rk s a n d h a s s o m e
in e f f ic ie n c ie s in t e r m s of d e s c r ib in g co m p le x a r e a s , b u t n e v e r t h e le s s it
h a n d le s b o th f o r m a ts .
S an D iego C o u n ty 1 in C a lif o r n ia is in th e p r o c e s s of c o m b in in g th e f ile
s t r u c t u r e s o f i t s c o a r s e p o ly g o n s y s t e m (a v e r s io n of PIOS) an d th e D IM E
s y ste m .
T h e d e g re e to w h ic h th i s h a s b e e n s u c c e s s f u l i s n o t know n.
T h e CGIS now h a s th e a b ility to a c c e p t d a ta r e l a te d to p o in t f o r m a ts .
i s a f a i r l y r e c e n t d e v e lo p m e n t2 (1973).
T h is
It w ould s e e m to le a d th e w ay to
lin k in g th e c a p a b ilitie s o f CGIS w ith th e f il e s o p h is tic a tio n o f GRDSR.
As
b o th s y s t e m s h a v e b e e n d e v e lo p e d w ith in th e s a m e g o v e rn m e n t, th i s m a y
p r e s e n t a n o p p o rtu n ity f o r c o m p le m e n ta r y d ev e lo p m en t.
It i s , h o w e v e r,
s ig n if ic a n t to n o te th a t th e CGIS h a s n o t a tte m p te d (and a t th e tim e o f w r itin g
h a s n o p la n s to a tte m p t) to a c q u ir e th e a b ility to s to r e n e tw o rk d a ta in i t s
m a in f il e s tr u c t u r e .
U n d o u b ted ly , th e a b ility to s to r e v a r io u s d a ta f o r m a ts in th e p r i m a r y f ile
s t r u c t u r e of a s y s t e m i s b e in g c o n s id e re d , a n d d e v e lo p m e n t a lo n g th e s e lin e s
i s ta k in g p la c e .
E q u a lly , s u c h a n a b ility w ould b e d e s ir a b le .
C o n s id e r a tio n
of th e f il e s t r u c t u r e s of th e t y p i c a l s y s t e m d e s c r ib e d in th is t h e s i s , h o w e v e r,
d o e s n o t le a d to th e c o n c lu s io n th a t m o d ific a tio n o r m e rg in g of e x is tin g
d e s ig n s w ill b e an e a s y p r o c e s s o r w ill le a d to e ffic ie n t p r o c e s s in g .
It i s
p r o b a b le th a t e ffic ie n t f il e s t r u c t u r e s f o r m u lti-m o d a l in p u t w ill h a v e to b e
d e s ig n e d w ith th e m ix tu re of d a ta f o r m a ts e x p lic itly p r e d e te r m in e d .
SUM M ARY
T h is c h a p te r h a s f o c u s s e d on th e s ta t u s of te c h n iq u e s u n d e r d e v e lo p m e n t f o r
th e n o n - g r a p h ic s to r a g e a n d c o m p u te r - a id e d m a n ip u la tio n o f s p a ti a l d a ta .
T h e i r r e g u l a r po ly g o n c a te g o r y of s y s t e m s f o r h a n d lin g s p a tia l d a ta w as
e x a m in e d a n d i t s c h a r a c t e r i s t i c s i l l u s t r a t e d w ith s p e c ific e x a m p le s .
The
c o m p u te r - a id e d p r o c e s s e s w e r e c o m p a re d w ith e q u iv a le n t m a n u a l p r o c e s s e s .
T h e t r e n d s in th e d e v e lo p m e n t of d ig itiz a tio n te c h n iq u e s , in te r a c tiv e m a n ip u la tio n of th e d a t a b a s e , o u tp u t d e v ic e s , a n d m u lti- f o r m a t s y s t e m s w e r e
a l s o e x a m in e d , a n d t h e i r p o te n tia l c o n trib u tio n to p r o c e s s e s f o r h a n d lin g
1. P e r s o n a l c o m m u n ic a tio n ,
S w itz e r, W. 1973.
T a y l o r 1973.
2. P e r s o n a l c o m m u n ic a tio n ,
185
s p a ti a l d a ta w a s c o n s id e re d .
S e v e r a l c o n c lu s io n s ca n b e d ra w n f r o m th e
e v id e n c e p r e s e n t e d .
T h e te c h n iq u e s of g r a p h ic to n o n -g ra p h ic c o n v e rs io n th a t w e r e n o te d to b e
m a jo r c o n s tr a in ts on c u r r e n t s y s t e m s r e m a in a s c o n s tr a in ts o n s y s te m s
u n d e r d e v e lo p m e n t.
D a n g e rm o n d 's1 g ra p h ic d e s c r ip tio n of th e d if f ic u ltie s
of d ig itiz a tio n e n c o u n te re d in th e r e l a ti v e ly a d v a n c e d P IO S s y s t e m w a s
p re se n te d .
O n ly w h e n m o r e a d v a n c e d d ig itiz a tio n te c h n iq u e s a r e e m p lo y e d ,
s u c h a s u s e of th e d r u m s c a n n e r b y CGIS, a r e th e o v e r a l l c o s ts o f c o m p u te r
te c h n iq u e s lo w e r e d to a c c e p ta b le le v e ls in c o m p a ris o n w ith th o s e o f e v e n
m e d iu m - to h ig h - le v e l m a n u a l p r o c e s s e s .
show n in th e CG IS c o s t a n a ly s is .
rem oved.
T h is c o m p a r is o n w a s c l e a r ly
T h e c o n s tr a in ts , h o w e v e r, a r e b e in g
S p e e d s of d ig itiz in g 20 to 30 ti m e s f a s t e r th a n c u r r e n t m e th o d s
c a n b e r e a s o n a b l y e x p e c te d .
T h is , c o u p le d w ith th e ad v e n t o f s u b s ta n tia l
v o lu m e s of n u m e r ic a l d a ta d ir e c tl y d e r iv e d f r o m s u r v e y p r o c e s s e s (su ch
a s E R T S -A d a ta ), ca n b e p r e d i c te d to r e s u l t in g r e a t e r v o lu m e s o f m e tr ic a lly
c o d e d n o n - g r a p h ic s p a ti a l d a ta in th e f o r e s e e a b le f u tu r e .
T h e p r o s p e c t o f in c r e a s in g v o lu m e s of n o n -g r a p h ic d a ta , b o th b y im p r o v e d
d ig itiz in g o r d if f e re n t g a th e r in g te c h n iq u e s a n d b y th e u s e o f h ig h - o r d e r
d a ta f o r m a t s s u c h a s i r r e g u l a r p o ly g o n s (o r l o w - o r d e r , h ig h -v o lu m e d a ta
f o r m a ts s u c h a s g r id s ) , b r in g s w ith it th e p r o b le m th a t th e p r o c e s s in g
c a p a c it ie s of c o m p u te r s m a y b e e x c e e d e d .
A lre a d y (in CGIS) it c a n b e n o te d
th a t s o m e p r o c e s s in g te c h n iq u e s (se c tio n in g ) w e r e d e te r m in e d b y c o m p u te r
p r o c e s s in g c a p a c ity a n d th a t th e f il e s t r u c t u r e (fr a m e s ) w a s d e te r m in e d b y
a n tic ip a te d d a ta v o lu m e s (o v e rla y s) r e l a te d to c o m p u te r p r o c e s s in g c a p a c ity .
T h is is n o t a fu n c tio n of s to r a g e c a p a c ity of a c o m p u te r (w hich i s p r a c t ic a lly
in f in ite ) , b u t o f th e a c c e s s tim e to th e v a r io u s f o r m s of s to r a g e .
As p resen t
c o m p u te r s a r e a p p a re n tly a p p ro a c h in g th e th e o r e ti c a l l i m i t s o f e l e c t r o m e c h a n ic a l s to r a g e , a new a p p ro a c h t o c o m p u te r m e m o ry ( o p tic a l s to r a g e ,
h o lo g r a p h ic m e m o r ie s ) m a y h av e to b e im p le m e n te d to re m o v e th i s c o n s tra in t.
T h is f a c t o r d o e s n o t in h ib it th e u s e of c u r r e n t s y s t e m s o r s e r io u s ly
in flu e n c e th o s e u n d e r d e v e lo p m e n t, b u t it w ill h a v e s ig n if ic a n t im p a c t if n o n g r a p h ic d a ta v o lu m e s a r e in c r e a s e d , a n d th e r e is e v e ry in d ic a tio n th a t th e y
w ill b e .
1. S ee q u o ta tio n on pp. 169-170 in th e te x t above f r o m D a n g e rm o n d 1971.
186
In c o n t r a s t to th e lim ita tio n s im p o s e d b y th e tr a n s f o r m a tio n o f d a ta to n o n g r a p h ic f o r m a ts a n d th e p o te n tia l c o n s tr a in ts of c o m p u te r p r o c e s s in g s p e e d ,
t h e r e is a s ig n if ic a n t u n d e r - u s e of th e a r c h i te c tu r e of c u r r e n t c o m p u te r s b y
e v e n th e m o s t a d v a n c e d s p a tia l d a ta h a n d lin g s y s te m s .
I t is n o t n e c e s s a r i l y
tr u e th a t th e m o s t co m p le x f ile s t r u c t u r e i s th e m o s t e ffic ie n t, b u t th e f ile
s t r u c t u r e s e m p lo y e d b y th e s y s te m s u n d e r d e v e lo p m e n t a r e e x tr e m e ly
s tr a i g h tf o r w a r d .
T h e s e c o n s id e ra tio n s le a d to th e g e n e ra l o b s e r v a tio n th a t
th e g r e a t m a jo r it y of c o m p u te r- a id e d s y s te m s in an y s ta t e o f d e v e lo p m e n t
h a v e b e e n d e s ig n e d in th e a b s e n c e of r e q u i r e m e n t s to m a n ip u la te d a ta in a
s o p h is tic a te d m a n n e r .
T h e o n ly s y s te m s th a t a r e d e s ig n e d to o p e r a te in a
u s e r e n v iro n m e n t, u n d e r th e c o n tr o l of a s y s t e m m o n ito r an d w ith a s u ite o f
c o m m a n d s to g e n e r a te d a ta m a n ip u la tio n s , a r e th e CGIS an d IN SIG H T.
N e ith e r of th e s e s y s t e m s co u ld b e c o n s id e r e d to h a v e u s e d th e f u ll c a p a c ity
of p r e s e n t - d a y c o m p u te rs f o r t h e i r f il e s t r u c t u r e s .
T h e s u ite of CG IS
c o m m a n d s i s lim ite d , in an y s e n s e of in te r r o g a tiv e s p a ti a l a n a ly s is , a n d th e
IN SIG H T f i l e s t r u c t u r e f a c i li ta te s r e a d in g a n d b r o w s in g r a t h e r th a n a n y
s u b s ta n tiv e m a n ip u la tio n .
N e ith e r i s lin k e d to a n y f o r m of s p a ti a l a n a ly s is
p r o g r a m o r s e t of p r o c e d u r e s th a t r e q u i r e c o m p le x d a ta m a n ip u la tio n s .
I t i s c l e a r th a t f u tu r e s y s t e m d e v e lo p m e n t w ill n e e d g r e a t e r in t e r a c t io n an d
d ir e c ti o n f r o m s y s t e m u s e r s .
A s s p a ti a l d a ta v o lu m e s in c r e a s e , an d if
th e s e d a ta a r e to b e m a n ip u la te d b y c o m p u te r , a n in c r e a s e c a n b e e x p e c te d
in th e r e q u i r e m e n t s f o r s p a tia l a n a ly s is of th e d a ta in a n o n - v is u a l m a n n e r
a n d f o r c o m b in e d v is u a l a n d n o n - v is u a l (in te ra c tiv e ) a n a ly s is .
C e r ta in ly ,
if im p r o v e m e n ts a r e to b e m a d e in s y s t e m s u n d e r d e v e lo p m e n t, th e y ca n
m o s t b e n e f ic ia lly b e a p p lie d to th e s e p r o c e s s e s .
T h e r e la tio n s h ip b e tw e e n
d a ta a v a i l a b i l i t y , d a ta h a n d lin g c a p a b ility , an d u s e r r e q u i r e m e n t s w ill b e
e x a m in e d in th e fo llo w in g c h a p te r s .
187
C H A P T E R 6 - A NALYSIS O F S PA T IA L DATA HANDLING C A PA B IL IT Y
IN T E R M S O F DATA C H A RA CTE R AND A V A ILA B ILITY :
A FRA M EW O R K FO R D ESC R IPT IO N O F G EO GRA PHIC
IN FO R M A T IO N SYSTEM S
T h e tw o p r e v io u s c h a p te r s h a v e e x a m in e d th e s ta tu s of e x is tin g c o m p u te r a id e d te c h n iq u e s f o r h a n d lin g s p a tia l d a ta .
T h e p u rp o s e of th i s c h a p te r is
to id e n tify th e c o n trib u tio n of th e v a r io u s te c h n iq u e s to o u r o v e r a l l a b ility
to h a n d le s p a t i a l d a ta .
A te n ta tiv e f r a m e w o r k is p ro v id e d w ith in w h ic h
s p a ti a l d a ta h a n d lin g s y s t e m s
u n d e rs to o d .
ca n b e lo c a te d an d t h e i r r e l a ti v e c a p a b ilitie s
B y e x te n s io n , it c a n a l s o b e u s e d to in tro d u c e th e r e la tio n s h ip s
b e tw e e n h a n d lin g c a p a b ility an d th e r e q u i r e m e n t s of th e u s e r .
ANALYSIS O F FR A M EW O R K
F r o m th e s ta n d p o in t o f th e s e s y s t e m s , s p a tia l d a ta ca n be c h a r a c te r iz e d
b y th e n a t u r e of th e lo c a tio n id e n tif ie r u s e d , and th e v o lu m e (n u m b e r of
p ie c e s ) of d a ta c a r r i e d in c o n c e r t w ith an y one s e t of lo c a tio n id e n tif i e r s .
L o c a tio n i d e n tif i e r s r a n g e f r o m th e m o s t e le m e n ta r y f o r m of e x t e r n a l
in d e x e s to e x p lic it b o u n d a ry d e fin itio n on th e s u r f a c e of th e e a r t h , w ith a
p o s itio n a l a c c u r a c y o f p lu s o r m in u s h a lf th e w id th of th e lin e .
T h e v o lu m e
of d a ta v a r i e s in s c a l e f r o m one o r tw o p ie c e s of d a ta p e r lo c a tio n id e n tif ie r
to l a r g e a m o u n ts up to 5 0 ,0 0 0 p ie c e s of d a ta p e r lo c a tio n id e n tif ie r , a r r a n g e d
in o v e rla p p in g c a te g o r ie s .
T h e t h i r d b a s ic v a ria b le of a s p a ti a l d a ta h an d lin g
s y s t e m i s th e r a n g e of c a p a b ilitie s f o r m a n ip u la tio n ; it e x te n d s f r o m e le m e n t a r y f o r m s of r e t r i e v a l up to co m p lex d a ta h a n d lin g o p e ra tio n s u n d e r th e
c o n tro l o f a s y s t e m m o n ito r .
T h e s e t h r e e v a r i a b le s (lo c a tio n id e n tif ie r , d a ta v o lu m e , an d m a n ip u la tio n
fa c ility ) c a n b e th o u g h t of a s th r e e a x e s of a cube (F ig . 6. 1) w ith in w h ich
th e s y s t e m s d e s c r i b e d in C h a p te r s 4 an d 5 ca n b e lo c a te d .
T h e u s e o f th e
d ia g o n a l a x is of th e cu b e a s a v e c to r of p o te n tia l f i l e - s t r u c t u r e c a p a b ility
w ill b e e x a m in e d l a t e r in th e c h a p te r .
It m u s t b e e m p h a s iz e d th a t th e v a lu e s of th e v a r ia b le s a lo n g e a c h a x is a r e
e s s e n ti a ll y a r b i t r a r y , a n d t h e i r r e l a ti v e p o s itio n s a r e u s e f u l o n ly a s g e n e ra l
in d ic a to r s of s y s t e m c h a r a c t e r i s t i c s .
T h e p r o g r e s s io n a lo n g e a c h a x is is
c e r t a in l y n o t li n e a r , a n d in a t l e a s t tw o c a s e s te n d s to b e lo g a r ith m ic , a s
1. A " s p a ti a l d a ta h a n d lin g s y s te m " in th i s s e n s e i s ta k e n to b e a s e t o f one
o r m o re c o m p u te r - a id e d te c h n iq u e s th a t ca n r e a d , s t o r e , m a n ip u la te , an d
d is p la y s p a ti a l d a ta .
188
w ill b e show n.
T h e r e a r e d is c o n tin u itie s in th e s e r i e s of v a lu e s a n d , h e n c e ,
im p lic it s te p s in th e s c a l e s .
In s h o r t, th e in t e r n a l s p a c e o f th e c u b e is
n o t s im p ly d e fin e d , a n d s y s t e m s ca n n o t b e p r e c i s e ly lo c a te d w ith in it .
As
m o r e in fo rm a tio n b e c o m e s a v a ila b le ab o u t v a r io u s s y s t e m s , i t m a y be
p o s s ib le an d w o rth w h ile to r e g r o u p o r r e f in e th e v a lu e s .
T h e a p p r o a c h is
p ro v id e d h e r e o n ly a s a c o n v e n ie n t f r a m e w o r k f o r d is c u s s io n o f s y s t e m
c h a ra c te ris tic s .
L o c a tio n
id e n tif ie r
F ig . 6. 1.
A x es o f d e s c r ip tiv e f r a m e w o rk .
T h e r a n g e of v a lu e s a lo n g e a c h a x is w ill b e e x a m in e d b r ie f ly b elo w .
T h e re-
a f t e r , th e v a r io u s s y s t e m s w ill b e lo c a te d w ith r e f e r e n c e to th e a x e s an d
t h e i r r e l a ti v e c h a r a c t e r i s t i c s w ill b e d is c u s s e d .
L o c a tio n I d e n tif ie r s
T h e v a r io u s a p p ro a c h e s u s e d to d e fin e a n d code th e lo c a tio n o f s p a ti a l d a ta
w e r e d is c u s s e d in s o m e d e ta il a t th e b e g in n in g of C h a p te r 4.
T o s u m m a r iz e
a n d s im p lify th a t d is c u s s io n , t h e r e a r e e s s e n ti a ll y th r e e c a te g o r ie s o f
m e th o d s f o r id e n tify in g lo c a tio n .
A r r a n g e d in a s c e n d in g o r d e r of. r e s o lu tio n ,
th e f i r s t c a te g o r y g iv e s a n a m e to th e lo c a tio n of th e d a ta e le m e n t w ith o u t
o th e rw is e d e fin in g i t s p o s itio n , th e s e c o n d d e s c r i b e s th e r e l a ti v e lo c a tio n
o f d a ta e le m e n ts , an d th e th i r d , u s in g v a r io u s le v e ls of p r e c i s io n , d e fin e s
th e lo c a tio n of th e b o u n d a ry 1 o f th e d a ta e le m e n t.
T h e s e r i e s o f lo c a tio n
i d e n tif i e r s , w ith e x a m p le s of t h e i r a p p lic a tio n , is il lu s tr a t e d in F ig . 6. 2.
1. A ll r e a l - w o r l d e le m e n ts of s p a ti a l d a ta h a v e b o u n d a rie s . P o in ts a r e
r e g a r d e d a s d a ta e le m e n ts w ith b o u n d a r ie s b u t no s ig n ific a n t d im e n s io n s ,
li n e s a s d a ta e le m e n ts w ith b o u n d a rie s b u t no s ig n ific a n t d im e n s io n in
o ne d ir e c tio n , an d a r e a s a s b o u n d ed d a ta e le m e n ts w ith tw o d im e n s io n s .
189
L o c a tio n i d e n t i f i e r s
T y p ic a l s y s t e m s
idthofE rro r within
w
original line
CGIS
CANADIAN H Y D R O G R A PH IC
AU T O M A P
Explicit
t
know
sytemBoundary
P IO S , M A P /M O D E L , GIM M S, N R IS
Nodol
Simple grid
Implicit
locatin
specifdRelative
External
index
only
F ig . 6. 2.
e .g .
Centroids of
unspecified areas
e.g. etc. ↑
Postal zone
City
County
Province
ountry
C
orld
W
D IM E , O E M , N O R D P L A N , SACS
SYM AP
M INN ESO TA
LUN R
GRDSR
F R IS
A D M IN ISTR A TIV E D A T A
CENSUS
L o c a tio n id e n tif ie r s w ith r e l a te d d a ta s e ts .
T h e s im p l e s t c a te g o ry of lo c a tio n id e n tif i e r s i s th e e x t e r n a l in d e x , a
n o m in a l co d e th a t id e n tifie s d a ta a s b e lo n g in g to a p a r t i c u l a r g e o g ra p h ic
a r e a o r lo c a tio n .
T h e v a lu e d o es n o t co n v e y r e l a ti v e lo c a tio n , w h ich in
th i s c a s e m u s t be d e te r m in e d b y r e f e r e n c e to an e x t e r n a l m e t r i c in d e x ,
ty p ic a lly a m a p .
W ith in th is c a te g o ry i t i s p o s s ib le to r e c o g n iz e a h ie r a r c h y
of n a m e s r e f e r r i n g to d e c re a s in g s iz e s of d a ta e le m e n t (and h e n c e in c r e a s in g
r e s o lu t io n of lo c a tio n ), f o r e x a m p le : w o r ld , c o u n try , p r o v in c e , c o u n ty ,
p o s ta l z o n e , s t r e e t n a m e , an d s t r e e t a d d r e s s .
P r o b a b ly th e o v e rw h e lm in g
p r o p o r tio n of n o n -m a p p e d d a ta w ith a n y lo c a tio n a l id e n tif i e r to d a y u s e s th i s
d e s c r i p tiv e m e th o d .
M o st tr a d iti o n a l c e n s u s a n d a d m in is tr a tiv e d a ta , f o r
e x a m p le , a r e co d e d o n ly b y th i s m e th o d .
T h e s e c o n d c a te g o ry c o n s is ts of id e n tif i e r s th a t c o n v ey th e r e l a ti v e lo c a tio n
190
o f th e d a ta e le m e n ts , b u t do n o t d efin e th e p o s itio n of t h e i r b o u n d a ry .
A ty p ic a l
e x a m p le of th i s c a te g o r y i s p o in t c o o rd in a te s th a t r e p r e s e n t th e lo c a tio n of
o th e rw is e u n s p e c ifie d a r e a s , a s in GRDSR1 an d F R IS 2.
A n o th e r e x a m p le is
th e DIM E3 s y s te m , w h ich p ro v id e s a to p o lo g ic a lly r ig o r o u s c o n n e c tiv ity code
f o r c ity s t r e e t s w ith o u t n e c e s s a r i l y m a p p in g th e r e s u ltin g n e tw o rk in s p a c e .
T h is l a s t e x a m p le i l l u s t r a t e s one of th e d iffic u ltie s in a b s o lu te a llo c a tio n of
s y s t e m s to c a te g o r ie s .
In th e D IM E s y s te m , c o o rd in a te v a lu e s c a n b e ad d e d
to i t s n e tw o rk n o d e s , a n d h e n c e it c a n b e r e g a r d e d a s a h ig h e r - o r d e r s y s t e m
(s e e F ig . 6. 2).
A ls o , s e v e r a l h i g h e r - o r d e r s y s te m s h av e th e a b ility to
c h a n g e th e d a ta f o r m a t.
Such c h a n g e s a r e fre q u e n tly m a d e to lo w e r - o r d e r
lo c a tio n id e n tif i e r s , a n d w hen o p e r a tin g in th a t m o d e th e s y s t e m s m ig h t b e
c o n s id e r e d to b e of a lo w e r o r d e r .
In g e n e r a l, h o w e v e r, s y s te m s a r e a l l o -
c a te d to th e c a te g o ry th a t r e p r e s e n t s th e h ig h e s t fu n c tio n th e y c a n c a r r y o u t.
T h e t h i r d c a te g o r y of lo c a tio n id e n tif i e r s c o m p r is e s th o s e u s e d in s y s t e m s
w h e re th e p o s itio n of th e b o u n d a ry of th e d a ta e le m e n t is im p lic itly o r
e x p lic itly know n.4
T h e lo w e s t o r d e r w ith in th i s c a te g o ry u s e s c e lls in a
s im p le g r id w h o se o r ig in i s m e tr ic a lly defin ed .
T h e r e s u lt in g lo c a tio n a l
c o d e s m a y b e m e tr ic ( c e ll c e n tr o id c o o r d in a te s , f o r ex a m p le) o r to p o lo g ic a l
(s u c h a s c e ll s e q u e n c e n u m b e r s ).
H o w e v e r, th e e s s e n ti a l c h a r a c te r is tic
i s th a t th e lo c a tio n of th e a c tu a l b o u n d a ry of th e c e ll is (im p lic itly ) know n to
th e s y s te m , w ith o u t b e in g f u r t h e r (e x p lic itly ) d efin e d b y a ll c o r n e r p o in ts o r
b y a s t r i n g of c o o rd in a te s of th e b o u n d a ry lin e s .
T h e r e is a fin e d is tin c tio n
in lo c a tio n a l p r e c i s io n b e tw e e n u s e of c e n tr o id c o o rd in a te s o f u n d efin ed a r e a s ,
a s in GRDSR, an d th e g ro u p in g of d a ta e le m e n ts of o th e r w is e u n s p e c ifie d
lo c a tio n in l a r g e g r id c e l l s , a s in LU N R .5
T h e im p lic it d e fin itio n of a
b o u n d a ry b e tw e e n s e t s of d a ta b y th e g r id c e ll m e th o d d o e s , h o w e v e r, p la c e
it in th e lo w e s t o r d e r of th e t h i r d c a te g o r y .
W ith in th i s g r id c e ll s u b -
c a te g o r y t h e r e a p p e a r s to e x is t a h ie r a r c h y of v a lu e s , ra n g in g f r o m la r g e
to s m a l l c e ll s iz e (in r e l a ti o n to th e s iz e an d r e g u l a r ity of d is tr ib u tio n of
s o u r c e d a ta e le m e n ts ), th a t i s , f r o m T y p e 1 a r b i t r a r y r e g u l a r - a r e a s y s t e m s 6
s u c h a s LUNR to T y p e 2 a r b i t r a r y r e g u l a r - a r e a s y s t e m s 6 s u c h a s SYM AP.7
1. S ta t is tic s C a n a d a 1972a, 1972b; s e e a ls o C h a p te r 4, p p .l l 1-115. 2. A lf r e d s s o n
e t a l. 1970, M e la n d e r e t a l. 1971. 3. C o rb e tt a n d F a r n s w o r th 1971; s e e a ls o
C h a p te r 4 , p p .116-122. 4 . "K now n" in th i s s e n s e m e a n s th a t th e b o u n d a ry p r o p e r t i e s c o n c e rn e d a r e r e c o r d e d in th e s to r a g e of th e d a ta h an d lin g s y s t e m an d
a r e th u s know n to th e s y s te m . 5. H a rd y e t a l. 1971a; s e e a ls o C h a p te r 4, pp.
9 9 -1 0 3 . 6. A s d e fin e d in C h a p te r 4 , p .98 . 7. H a r v a r d U n iv e r s ity 1968; s e e a lso
C h a p te r 4 , pp. 105-109.
191
E x p lic it b o u n d a rie s of d a ta e le m e n ts f o r m th e h ig h e r o r d e r s of th e c a te g o ry .
L in e s d e s c r i b e d b y w id e ly s p a c e d n o d a l p o in ts m a y b e th o u g h t o f a s s im p le
( lo w e r - o r d e r ) e x a m p le s of e x p lic it b o u n d a rie s .
T h e h ie r a r c h y e x te n d s u p w a rd s
a s th e r e s o lu t io n o f th e im a g e d e s c r ip tio n i n c r e a s e s , a s , f o r e x a m p le , w hen
th e n u m b e r of p o in ts u s e d to d e s c r i b e a lin e in c r e a s e s .
B e c a u s e lo c a tio n
id e n tif i e r s c a n b e u s e d f o r v a r io u s ty p e s of d a ta e le m e n t (p o in ts, li n e s , a r e a s )
w ith in o n e s y s t e m , it i s d iffic u lt to a llo c a te s y s te m s a b s o lu te ly to c a te g o r ie s ,
b u t a llo c a tio n of s y s t e m s i s g e n e r a lly b a s e d on th e le v e l of lo c a tio n id e n tif ie r
u s e d to d e fin e i t s m o s t c o m p le x d a ta e le m e n t.
T y p ic a l of th e s im p l e s t f o r m
of e x p lic it b o u n d a ry id e n tif i e r s a r e th o s e u s e d in th e D IM E, O EM , 1
N O R D P L A N ,2 a n d SACS3 n e tw o rk s y s t e m s .
H ig h e r in lo c a tio n a l p r e c is io n
b u t s t i l l a t th e " c o a r s e p o ly g o n " le v e l a r e th e G IM M S,4 P IO S , 5 M A P /M O D E L ,6
an d N RIS7 s y s t e m s .
A U T O M A P8 a n d th e C an a d ian H y d ro g ra p h ic S y ste m 9
a tte m p t to d e fin e t h e i r b o u n d a r ie s w ith g r e a t e r p r e c is io n .
T y p ic a l o f th e
h i g h e r - o r d e r s y s t e m s i s C G IS ,10 w h ic h lo c a te s a l l b o u n d a rie s w ith a n e r r o r
o f l e s s th a n h a lf th e w id th of th e o r ig in a l lin e .
T h e s p a c in g of th e c a te g o r ie s a n d s u b c a te g o r ie s along th e a x is il lu s tr a t e d
in F ig . 6. 2 i s c o m p le te ly s u b je c tiv e , b u t it i s s tr a ig h tf o r w a r d , an d r e c o g n iz e s th e a s c e n d in g o r d e r of r e s o lu tio n of lo c a tio n a l id e n tific a tio n in th e
d iffe re n t c a te g o r ie s .
T h e lo w e r h a lf of th e a x is i s o cc u p ie d b y te c h n iq u e s
th a t do n o t e x p lic itly d e fin e th e p o s itio n of th e r e a l - w o r l d d a ta e le m e n t, b ut
u s e s o m e s u r r o g a te . 11 T h is lo w e r p a r t of th e a x is is a r b i t r a r i l y s u b d iv id e d
in to t h r e e e q u a l p a r t s , e a c h r e p r e s e n t in g a m o r e p r e c i s e m e th o d w ith in th is
a p p r o a c h t o lo c a tio n id e n tific a tio n ; w ith in e a c h s u b d iv is io n , a n a s c e n d in g
o r d e r of lo c a tio n a l r e s o lu t io n i s a s s u m e d .
T h e u p p e r h a lf o f th e a x is is
o c c u p ie d b y te c h n iq u e s th a t m a k e a n a tte m p t to define th e p o s itio n o f th e
b o u n d a r ie s of th e r e a l - w o r l d d a ta e le m e n ts in s p a c e .
A g ain , a n a s c e n d in g
o r d e r of lo c a tio n a l r e s o lu t io n i s a s s u m e d w ith in th e e n t ir e s u b c a te g o ry .
T he
r e l a ti v e r e s o lu t io n of lo c a tio n id e n tif i e r s u s e d in th e d if fe re n t s y s te m s ca n
b e id e n tifie d r e a s o n a b ly c l e a r l y f r o m th i s a r r a n g e m e n t alo n g th e a x is .
I. O b s e r v a to ire É co n o m iq u e Mé d i t e r r a n é en 1971. 2. P e r s o n a l co m m u n ic a tio n ,
S a lo m o n ss o n 1973. 3. C a lk in s 1967, B a rb 1968. 4. W augh 1972. 5. D a n g e r m o n d 1971; s e e a l s o C h a p te r 5 , pp. 145-152. 6. A rm s 1967, 1968, 1969, 1970.
7. B o ein g 1972a, 1972b. 8. S c h m id t, W. 1969; s e e a ls o C h a p te r 4 , pp. 122-126.
9. B o y le 1970a, 1971. 10. T o m lin s o n , R . F . 1967; s e e a l s o A ppendix.
11. A p o s s ib le e x c e p tio n i s th a t s o m e r e a l - w o r l d d a ta e le m e n ts m a y a c tu a lly
h av e th e f o r m o f g r id s , a n d m a y b e r e p r e s e n t e d b y a g rid .
192
Volume of Related Data The
s e c o n d v a ria b le o f s p a tia l d a ta h a n d lin g s y s te m s is th e v o lu m e o f p ie c e s
o f r e l a t e d d a ta t h a t c a n b e c a r r i e d a t a n y o n e lo c a ti o n w i th in o n e s e t
o f lo c a tio n id e n tifie rs . T h is v a ria b le is th e s e c o n d a x is o f th e re c o rd
plane (the other axis being that of the location identifier).
T h e u n it o f m e a s u r e m e n t o f v o lu m e is im p o r ta n t, b e c a u s e t h e r e is a d i f f e r e n c e
b e tw e e n b in a r y b it s o f s to r a g e , w h ic h r e p r e s e n t th e - m o s t e f f ic ie n t f o r m o f
c o m p a c tio n a n d h e n c e th e tru e v a lu e o f d a ta v o lu m e th a t h a s to b e h a n d le d b y
a n y s y s te m , a n d p ie c e s o f d a ta , w h i c h a r e r e c o g n iz a b le e l e m e n ts o f r e a lw o r ld d a t a . T h e r e la t io n s h ip b e t w e e n th e t w o i s s tr a ig h tf o r w a r d a n d c a n b e
e x p r e s s e d a s th e to ta l n u m b e r o f c la s s if ic a ti o n s o r g r o u p i n g s u s e d ( o r a t le a s t
th e n e x t h ig h e s t b in a r y n u m b e r th a t w ill h o ld th a t n u m b e r o f c la s s if ic a tio n s )
fo r e a c h c a te g o ry o r p ie c e o f d a ta o r d a ta e le m e n t, th a t is :
Category n
∑ C lassificatio n G ro u p s = M ag n itu d e o f B its o f D ata
C ategory 1 W ith th e r e la tio n s h ip e x p r e s s e d , p ie c e s c a n b e u s e d a s th e u n its to
s u b d iv id e th e a x is re p re s e n tin g th e v o lu m e o f re la te d d a ta , b e c a u s e th e
re la tio n sh ip b e tw e e n p ie c e s o f d a ta a n d th e c o n te n t o f a c tu a l sy ste m s is c o n sid e ra b ly
e a sie r to u n d e rsta n d . T h e s u b d iv is io n o f th e a x is is illu stra te d in F ig . 6 . 3 .
C A N .H Y D R O
T y p ic a l
e x a m p le s
SY M A P
AUTOM AP
P IO S
LUNR
M A P /M C D E L F R I S C G I S S A C S G R D S R
M IN N
D IM E
WWW
CEN SU S
N u m b e r of p ie c e s
o f d a ta a t a n y o n e
lo c a tio n
F ig . 6. 3.
C a te g o r ie s of v o lu m e of r e l a t e d d a ta w ith e x a m p le s of
ty p ic a l s y s te m s .
In th e il lu s tr a t io n , s ix c a te g o r ie s h av e b e e n id e n tifie d .
A t th e lo w e r (left) end
o f th e a x is th e r e a r e tw o c l e a r l y d is tin g u is h e d c a te g o r ie s .
F a r t h e r alo n g th e
a x is th e p ic tu r e i s l e s s c l e a r , b o th a s to s ig n ific a n t g ro u p in g s an d a s to th e
193
e x a c t d a ta c o n te n t of a n y one s y s te m .
In th is p a r t of th e a x is , o v e rla p p in g
r a n g e s h a v e b e e n u s e d to d is tin g u is h s m a l l, m e d iu m , la r g e , a n d v e r y la r g e
v o lu m e s o f r e l a t e d d a ta .
T h e p r o g r e s s io n i s c e rta in ly n o t li n e a r , an d e v e n
,in th i s s im p lif ie d i l l u s t r a t i o n it c a n be s e e n to b e a p p r o x im a te ly lo g a r ith m ic .
T h e f i r s t c a te g o r y c o n ta in s one p ie c e of d a ta p e r lo c a tio n .
T h is r e p r e s e n t s
a n e n tity th a t s ta n d s b y it s e l f , s u c h a s th e p r e s e n c e o r a b s e n c e o f snow a t a
p a r t i c u l a r lo c a tio n o r , m o r e co m m o n ly , th e p r e s e n c e o r a b s e n c e o f a r o a d
a t a p a r t ic u l a r lo c a tio n .
T h is c a te g o r y in c lu d e s th e co m m o n ly re c o g n iz e d
im a g e -h o ld in g b it- p la n e fo u n d in im a g e re p ro d u c tio n s y s t e m s s u c h a s
A U T O M A P, an d a l s o th e g r id c e ll s y s t e m s r e s t r i c t e d to on e v a lu e p e r g r id
c e ll s u c h a s SYM A P.
T h e s e c o n d c a te g o r y c o m p r is e s r e c o r d s th a t c a n c o n ta in tw o p ie c e s o f r e l a te d
d a ta p e r lo c a tio n , a n d f r o m th e v ie w p o in t of s y s t e m c o n te n t it i s th e f i r s t
c a te g o r y w h e re p ie c e s o f d a ta c a n b e r e l a te d to. one a n o th e r , a t o n e lo c a tio n .
I t b e c o m e s p o s s ib le to c o n s id e r tim e in th e d a ta s tr in g , an d to m a n ip u la te
o v e r la y s .
T y p e s o f s y s t e m s w ith in th is s u b d iv is io n in c lu d e th e C a n a d ia n
H y d ro g ra p h ic S y s te m 1 a n d s im p le v e r s io n s of th e M A P /M O D E L s y s te m ,
a lth o u g h th e l a t t e r i s c a p a b le of e x te n s io n in to th e t h i r d c a te g o r y .
T h e t h i r d c a te g o r y c o n ta in s d a ta r e c o r d s w ith a s m a l l n u m b e r o f p ie c e s of
d a ta a t e a c h lo c a tio n , ty p ic a lly 2 to 100.
In to th i s s u b d iv is io n c o m e s u c h
s y s t e m s a s F R IS , N C C ,2 O EM , P IO S , an d th e CGIS in i t s c u r r e n t s ta t u s ,
a lth o u g h th e l a s t of th e s e s y s t e m s h a s th e c a p a c ity to ex p a n d in to th e f o u r th
s u b d iv is io n .
T h e fo u rth c a te g o r y h a s a m e d iu m n u m b e r of p ie c e s of d a ta a s s o c ia te d w ith
e a c h lo c a tio n id e n tif i e r , ty p ic a lly 50 to 1 ,0 0 0 .
In c lu d e d in th i s c a te g o r y a r e
th e d a ta - in te n s iv e c e n s u s ty p e s of r e c o r d s s u c h a s th e GRDSR s y s te m , D IM E,
SACS, a n d th e LU N R ty p e o f s y s te m .
In th e fifth c a te g o r y , l a r g e n u m b e rs of p ie c e s of d a ta a r e a s s o c ia te d w ith
e a c h lo c a tio n i d e n tif i e r , ty p ic a lly 500 to 1 0 ,0 0 0 .
E x a m p le s o f th i s s u b -
d iv is io n a r e t r a d iti o n a l c e n s u s - d a ta h a n d lin g s y s t e m s , w h e r e la r g e n u m b e r s
o f v a r i a b le s a r e g a th e r e d f o r a r e a s lo c a te d b y n a m e .
T h is c a te g o r y i s a ls o
c h a r a c te r iz e d b y d a ta s tr i n g s w h e r e th e a t tr ib u t e s a r e m e a s u r e d a t r e p e a te d
1. B o y le 1970a, 1971.
2. S ym ons 1972a.
194
ti m e in t e r v a l s , th u s p ro d u c in g la r g e v o lu m e s of d a ta .
A n e x a m p le of th is
ty p e w o u ld b e th e in fo r m a tio n a tta c h e d to one lo c a tio n su c h a s a w e a th e r
s ta t io n on a 10- y e a r s e r i e s o f w e a th e r m a p s , e a c h p ro d u c e d e v e r y h o u r.
T h e e x i s t in g w o r ld -w id e w e a th e r s y s t e m h a s d a ta r e c o r d s in th is c a te g o ry .
T h e s ix th c a te g o r y h a s a v e r y la r g e n u m b e r of p ie c e s of d a ta a s s o c ia te d w ith
e a c h lo c a tio n id e n tif i e r .
in fin ity .
T h e r a n g e is s u g g e s te d to ex te n d f r o m 5 ,0 0 0 to
N o d a ta s y s t e m know n to th e a u th o r c u r r e n t ly h a n d le s d a ta v o lu m e s
in th i s c a te g o r y , b u t i f m a n y l a r g e f i l e s o f d a ta w e r e in te g r a te d o n a s p a tia l
b a s i s s u c h v o lu m e s m ig h t c o n c e iv a b ly o c c u r in th e f u tu r e .
T h e s ix c a te g o r ie s g ro u p v a r io u s ty p e s of s y s te m s to g e th e r a n d show in
s e q u e n tia l o r d e r o f m a g n itu d e th e im p a c t of th e r e l a te d d a ta v o lu m e o n th e
f i l e s t r u c t u r e s th a t m u s t b e in c o r p o r a te d in to th e v a r io u s s y s t e m s .
No
a tte m p t h a s b e e n m a d e a t th i s s ta g e to e v a lu a te th e d e g r e e of im p a c t of
r e l a t e d d a ta v o lu m e on s y s t e m d e s ig n .
I t is p ro b a b ly not li n e a r .
M a n ip u la tio n F a c i l i t i e s
T h e t h i r d v a r i a b le is th a t of th e m a n ip u la tio n f a c i li tie s in c o r p o r a te d in th e
s y s te m .
T o e s ta b lis h a h ie r a r c h y of m a n ip u la tio n f a c i li tie s , it i s n e c e s s a r y
to e s ta b lis h s o m e r e l a t i v e m e a s u r e of th e e ffo r t n e e d e d to p r o v id e th e m , th a t
i s , s o m e m e a s u r e to id e n tify w h ic h m a n ip u la tio n s a r e e a s y a n d w h ic h a r e
m o r e d iffic u lt.
F o r e a c h m a n ip u la tio n , one o r m o r e lo g ic a l o p e r a tio n s m u s t
b e p e r f o r m e d u p o n th e d a ta to p ro d u c e th e d e s ir e d r e s u l t s .
A lo g ic a l o p e r a -
tio n i s a ch a n g e in d a ta v a lu e , a c o m p a r is o n , o r m o v e m en t of th e d a ta e le m e n t.
A h ie r a r c h y of m a n ip u la tio n f a c i li tie s c a n b e b a s e d on th e in c r e a s in g n u m b e r
of lo g i c a l o p e r a tio n s th e y p |n t a i n .
A d is tin c tio n s h o u ld b e m a d e a t th i s p o in t b e tw e e n a lo g ic a l o p e r a tio n a n d a
p h y s ic a l o p e r a tio n w ith in th e c o m p u te r s y s t e m its e lf .
A ch a n g e in d a ta v a lu e ,
f o r e x a m p le , c a n b e a c c o m p lis h e d b y a n y of th e p h y s ic a l o p e r a tio n s o f a d d itio n ,
s u b tr a c tio n , m u ltip lic a tio n , o r d iv is io n , e i th e r s in g ly o r in s e q u e n c e ( m u ltip lic a tio n a n d d iv is io n a r e in th e m s e lv e s a s e q u e n c e of th e p h y s ic a l o p e r a tio n s
of a d d itio n o r n e g a tiv e ad d itio n ). T h e r e s u l t o f th e s e q u e n c e of p h y s ic a l
o p e r a tio n s , h o w e v e r, i s a lo g ic a l o p e ra tio n , th e ch an g e in d a ta v a lu e .
T h e s e r i e s o f m a n ip u la tio n f a c i l i t i e s a r e la id o u t a lo n g th e th i r d a x is o f th e
195
cu b e in F ig . 6. 4.
T h r e e s ig n if ic a n t c a te g o r ie s o f s y s t e m c a n b e id e n tifie d :
th o s e w ith o u t o v e r la y c a p a b ility , th o s e w ith o v e rla y c a p a b ility , an d th o s e
w ith a s ig n if ic a n tly d e v e lo p e d m o n ito r s y s t e m o r q u e ry la n g u a g e , o r both.
M a n ip u la tio n
f a c ilitie s
O v e rla y
Number of o p e r a tio n s
Monitor system a n d
query la n g u a g e
T y p ic a l s y s t e m s
CGIS
C A N . HYDRO
GIMMS
P IO S , M A P /M O D E L , NRIS
N o n - o v e rla y
O B L IX , SYMVU
F ig . 6. 4.
SY M A P, D IM E , G RDSR, P R IS , SACS
WWW, N O R D P L A N , O EM
AUTOM AP
L U N R , MINN
CENSUS
M a n ip u la tio n f a c i li tie s a n d t h e i r r e l a te d s y s te m s .
L e v e l 1. W ith in th e f i r s t c a te g o ry , th e h ie r a r c h y of d a ta m a n ip u la tio n c a n be
la id o ut.
T h e s i m p l e s t c a p a b ility (le v e l 1) i s b a s ic d a ta r e t r i e v a l , a s in g le
lo g ic a l "M o v e" o p e ra tio n .
T h e d a ta c o n te n t is n o t m a n ip u la te d b u t i s m e r e ly
r e p r o d u c e d on a n e x t e r n a l s to r a g e m e d iu m , w h ich co u ld b e a p ie c e o f p a p e r.
T h is f i r s t e x a m p le i l l u s t r a t e s th e d iff e re n c e b e tw e e n lo g ic a l an d p h y s ic a l
o p e r a tio n s : th e lo g ic a l M ove o p e r a tio n m a y r e q u i r e s e v e r a l p h y s ic a l o p e r a tio n s .
T h e s e c a n in c lu d e : D efine w h a t i s b e in g lo o k e d f o r ; R e a d th e in p u t
r e q u e s t in fo rm a tio n ; A n a ly se th e c o n te n t of th e r e q u e s t; M ove f r o m e x te r n a l
196
m e d iu m to s to r a g e to allow c o m p a r is o n in te r n a lly ; S e a rc h th e ta p e to fin d th e
in fo rm a tio n (S e a rc h i t s e l f i s m a d e up of R e a d , C o m p a re , I n c r e m e n t, Move
ta p e , R e p e a t; w h en e q u a l; C o m p a re a n d M ove e le m e n t); D e te rm in e w h at p ie c e
o f e x t e r n a l s to r a g e h a s to b e r e f e r e n c e d ( c a rd p u n ch , p r i n t e r , e t c .) ;
R e - f o r m a t a s r e q u i r e d to s a ti s f y th e r e q u e s t , (th is is u s u a lly a co m p lex
M ove o p e r a tio n , alth o u g h it c a n b e done a s p a r t o f a s o p h is tic a te d P r i n t
o p e ra tio n ); an d O u tp u t (p r in t, p u n ch , o r d is p la y ).
T h is to t a l b a s ic r e t r i e v a l p r o c e s s m a y ta k e b e tw e e n s ix ( P L /1 ) a n d a p p r o x i m a te ly 200 ( A s s e m b le r la n g u ag e) in s tr u c tio n s , d ep e n d in g on th e le v e l of
c o m p u te r s y s t e m a n d th e la n g u a g e b e in g u s e d .
In l a r g e r an d m o r e ad v a n ced
c o m p u te r s , p a r t i c u l a r l y th o s e w ith v ir t u a l m e m o ry o p e r a tin g s y s t e m s , th e
e x t e r n a l m e m o r y i s in m a n y w a y s a n e x te n s io n of th e in t e r n a l s to r a g e an d
th e in s tr u c tio n s r e q u i r e d a r e g r e a t ly s im p lifie d .
H o w e v er, th e p r o c e s s
fo llo w e d in b a s i c d a t a r e t r i e v a l is th a t of r e p r o d u c in g , on a n e x te r n a l
m e d iu m , m a t e r i a l th a t a l r e a d y e x i s t s on a n in t e r n a l m e d iu m .
T h is i s
d e s c r ib e d a s a lo g i c a l M ove, a n d i s one lo g ic a l o p e r a tio n .
F u r t h e r le v e ls o f c a p a b ility f o r m a n ip u la tio n w ill b e d e s c r i b e d a s c o m b in a tio n s of s u c h lo g i c a l o p e r a tio n s .
In e a c h c a s e th e n u m b e r of lo g ic a l o p e r a -
tio n s s p e c if ie d m a y b e r e p e a te d a s o fte n a s n e c e s s a r y to c o m p le te th e m a n ip u la tio n .
A t th e r i s k of n o t id e n tify in g s u b tle d if f e re n c e s in m a n ip u la tio n
f a c ility , a n d to s im p lif y d is c u s s io n d iv id in g th e c a p a b ilitie s f o r m a n ip u la tio n
in to o n ly a few l e v e ls , o p e ra tio n s th a t a r e lo g ic a lly th e s a m e o r th a t co u ld
lo g ic a lly b e done in one s te p w ill b e g ro u p e d a s one lo g ic a l o p e r a t i o n .
L e v e l 2. T h e s e c o n d le v e l o f c a p a b ilitie s i s th e r e s u l t of tw o lo g ic a l o p e r a tio n s ,
a n d th e s e c a n n o n - in t e r a c t iv e l y p ro v id e d a ta s u m m a r y , e lim in a tio n of li n e a r
d is to r t io n , c l a s s i f ic a t io n ch a n g e, s e le c tiv e s e a r c h , s c a l e c h a n g e , p r o je c tio n
c h a n g e , o r m e a s u r e m e n t of s tr a i g h t- li n e d is ta n c e b e tw e e n p o in ts .
T h ese
f a c i li tie s a r e d e s c r i b e d belo w ; it sh o u ld b e n o te d th a t th e m a n ip u la tio n
f a c i li tie s m u s t r e m a in n o n - in te r a c tiv e to b e c l a s s i f ie d a t le v e l 2.
D a ta s u m m a r y i s a c h ie v e d b y th e c o m b in a tio n of th e lo g ic a l o p e r a tio n s M ove
(to a c q u ir e data) an d C hange in D ata V alu e.
E lim in a tio n of li n e a r d is to r tio n ,
th e r e v i s i o n of th e lo c a tio n of s p a tia lly d is tr i b u te d p o in ts in a li n e a r fa s h io n
197
on o n e a x is , i s a c h ie v e d b y a lo g ic a l C o m p a re o p e r a tio n (a g a in s t s ta n d a rd s )
a n d a lo g ic a l C hange in D a ta V alu e.
T h e l a t t e r i s u s u a lly a co m p lex o p e ra tio n
of m u ltip ly in g a n d d iv id in g , w h ich p r o d u c e s a s h if t, on one c o o rd in a te a t a
t i m e , f r o m o n e p o s itio n to a n o th e r .
C la s s if ic a tio n change i s b ro u g h t ab o u t
b y a lo g ic a l C o m p a re (of th e e x is tin g d a ta v a lu e s w ith a ta b le o f d a ta v a lu e s ,
to fin d th e m a tc h in g e n t r y f o r th e s u b s e q u e n t su b stitu tio n ) a n d a lo g ic a l M ove
(to e f fe c t th e s u b s titu tio n ).
S e le c tiv e s e a r c h i s c a r r i e d o u t b y a lo g ic a l Move
to g e t th e d a ta , fo llo w e d b y a lo g ic a l C o m p a re (a g a in s t th e r e q u e s t).
S cale
c h a n g e an d P r o je c tio n c h a n g e , lik e E lim in a tio n of li n e a r d is to r tio n , a r e a
c o m b in a tio n of lo g ic a l C o m p a re a n d lo g ic a l C hange in D ata V alu e.
The
m e a s u r e m e n t of th e s t r a i g h t - l i n e d is ta n c e b e tw e e n tw o p o in ts i s a c h ie v e d b y
a lo g ic a l M ove to a c q u ir e th e s e c o n d p o in t an d a lo g ic a l C a lc u la te (C hange in
D a ta V alu e ).
A lo g ic a l C a lc u la te is th e s a m e a s a C hange in D ata V alu e w h e re
th e ch a n g e i s m a d e b e tw e e n tw o v a r i a b le s o r b e tw e e n a v a r ia b le a n d a
r e f e r e n c e v a lu e ; th a t is , it i s a p a r a m e t r i c ch a n g e in d a ta v alu e.
T h e a b ility to c a r r y o u t m o r e th a n one of th e s e m a n ip u la tio n s n o n - in te r a c tiv e ly
e s ta b lis h e s a s u b h ie r a rc h y w ith in le v e l 2.
H o w e v er, a s lo n g a s th e m a n ip u la -
tio n s a r e n o n - in t e r a c t iv e , th e s y s t e m i s s t i l l c o n s id e r e d to b e w ith in th e le v e l.
T h e s a m e s u b h ie r a r c h ic a l g ro u p in g c a n b e a p p lie d w ith in o th e r h ig h e r le v e ls .
T r a d iti o n a l c e n s u s s y s t e m s in v o lv in g s u m m a ry , LU N R , a n d th e M in n eso ta
S y s te m (MINN)1 c a n b e c o n s id e r e d a s e x a m p le s of le v e l 2 s y s te m s .
L e v e l 3.
T h e t h i r d le v e l of c a p a b ilitie s i s a r e s u l t of t h r e e lo g ic a l o p e ra tio n s .
T h e s e p ro v id e f o r m e a s u r e m e n t, e lim in a tio n of n o n - lin e a r d is to r tio n , th e
a b ility to g e n e ra te ( c i r c le s a n d p o ly g o n s), a n d th e a b ility to c a r r y out
s t a t i s t i c a l g a th e r in g .
M e a s u re m e n t c a n c o n s is t of a r e a c a lc u la tio n s , d e te rm in a tio n o f d is ta n c e a lo n g
a n i r r e g u l a r lin e b e tw e e n p o in ts , p e r i m e t e r m e a s u re m e n t, an d th e co u n t of
p o in ts w ith in a r e a s .
In a r e a c a lc u la tio n , th e a c tu a l m e a s u r e m e n t p r o c e s s is
a s s u m e d to s t a r t w h e n th e d a ta h a v e b e e n found on th e a p p r o p r ia te f ile an d a
v e r t e x on th e b o u n d a ry h a s b e e n id e n tifie d a s a n a d d r e s s of th e a r e a lo c a tio n .
A ty p ic a l a n d s tr a i g h tf o r w a r d a r e a c a lc u la tio n (CGIS2) u s e s th e s ta n d a r d
a lg o r ith m f o r su b te n d e d a r e a s .
T h e f i r s t o p e r a tio n is a lo g ic a l C o m p a re (at
th e g iv e n s t a r t i n g p oint) w ith th e b o u n d a ry d e fin itio n , to d e te r m in e th e n e x t
1. B o r c h e r t 1969.
2. S ee A ppendix.
198
p o in t on th e b o u n d a ry .
T h is m a y b e a lo g ic a l M ove, d e p e n d in g o n th e s tr u c t u r e
of th e d a ta s to r a g e ; it i s s o in th e c a s e o f CGIS, w h e re e a c h v e r t e x w o u ld
c o n ta in th e d ir e c tio n an d th e d is ta n c e of th e n e x t v e r t e x on th e s e g m e n t.
The
c o m p a r is o n w o u ld , h o w e v e r, b e im p lic it on th e m ove t o th e n ex t v e r te x .
The
l o g i c a l C o m p a re is fo llo w e d b y a lo g ic a l C a lc u la te (of th e a r e a s u b te n d e d ),
a n d a n o th e r lo g ic a l C a lc u la te (to c r e a te th e to ta l).
T h e d is ta n c e a lo n g an i r r e g u l a r lin e b e tw e e n tw o p o in ts , o r a p e r i m e t e r , a
s p e c i a l c a s e w h e r e th e lin e f o r m s a c lo s e d lo o p , is o b ta in e d b y m e a s u r in g
th e le n g th of th e s tr a i g h t- li n e s e g m e n ts th a t m a k e up th e i r r e g u l a r lin e and
s u m m in g th e r e s u l t s .
B oth m a n ip u la tio n s a r e m a d e up of a lo g ic a l M ove (to
g e t th e p o s itio n of th e en d o f th e s tr a i g h t- li n e s e g m e n ts ); a lo g ic a l C a lc u la te
(of th e s tr a i g h t- li n e le n g th of th a t s e g m e n t); a n d a lo g ic a l C a lc u la te (to
p ro d u c e th e to ta l) .
A s th e m a n ip u la tio n s b e c o m e in c r e a s in g ly c o m p le x , th e y
m a y b e a c h ie v e d b y s e v e r a l s e t s of lo g ic a l o p e ra tio n s r a t h e r th a n b y ju s t one
s e t.
In th i s d is c u s s io n , a m a n ip u la tio n w ill g e n e ra lly b e d e s c r ib e d in a
s im p le f o r m , to in d ic a te th e le v e l in th e h ie r a r c h y of m a n ip u la tio n s a t w h ich
th a t p a r t i c u l a r k in d o f m a n ip u la tio n b e c o m e s p o s s ib le .
A co u n t of p o in ts w ith in a n a r e a (polygon), a n o th e r fu n c tio n o f m e a s u r e m e n t,
c a n b e a c h ie v e d in v a r io u s w a y s .
T h e s im p le to p o lo g ic a l te c h n iq u e i s to m o v e
f r o m th e g iv e n p o in t in a u n ifo r m d ir e c tio n to a n a x is , a n d co u n t th e n u m b e r
o f in t e r s e c ti o n s m a d e w ith th e b o u n d a ry of th e p r e s c r ib e d a r e a .
T h is
a lg o r ith m i s u s u a lly m a d e u p of a lo g ic a l M ove (to g e t th e n e x t p o in t); a
lo g ic a l C a lc u la te (of th e n u m b e r of in t e r s e c ti o n s c r o s s e d g o in g to th e a x is);
a n d a lo g ic a l C a lc u la te (to co u n t th e n u m b e r o f p o in ts).
D iffe re n t a p p ro a c h e s
to th e co u n t of p o in ts w ith in poly g o n s a r e u s e d in v a r io u s s y s t e m s .
T h e d ig ita l
a p p r o a c h to co u n t th e p o in ts w ith in th e p olygon, u s e d in th e M A P /M O D E L
s y s t e m , a n d th e a p p ro a c h u s e d in th e CGIS to lo c a te th e a r e a in to w h ich a
p o in t f a l l s r a t h e r th a n to co u n t th e p o in ts w ith in a n a r e a , b o th r e q u i r e th r e e
lo g i c a l o p e ra tio n s .
The Generate f a c i li ty is th e a b ility to p ro d u c e c i r c l e s , p o ly g o n s , an d p o in ts
th a t m u s t b e know n to th e s y s te m .
T h e p r o c e s s of g e n e ra tio n i t s e l f a s s u m e s
th a t th e p o s itio n o f th e it e m to b e g e n e ra te d i s s p e c ifie d .
T h e r e a f te r , th e
g e n e ra tio n of th e it e m p r o c e e d s th ro u g h th e lo g ic a l o p e r a tio n M ove (to a c q u ir e
199
th e d a ta , in c lu d in g th e s p e c if ie d p o s itio n ); a lo g ic a l C a lc u la te (to d e te r m in e
th e d is ta n c e to th e b o u n d a ry f r o m th e ite m c o n c e rn e d ); an d a lo g ic a l
C a lc u la te (to d e te r m in e th e m o v e m e n t to th e n e x t v e r t e x p o in t).
R e p e titio n
of th i s p r o c e s s g e n e r a te s th e r e q u i r e d f ig u r e o r p o in t an d p la c e s it in
s to r a g e f o r f u r t h e r u s e .
S ta t is tic a l g a th e r in g i s th e p r o c e s s of s e le c tiv e ly s e a r c h in g f o r ite m s
a c c o r d in g to a g iv e n p r o f ile , and th e a p p lic a tio n of a s p e c if ie d s t a t i s t i c a l
c a lc u la tio n to th o s e s e le c te d .
T h e m a n ip u la tio n c a n b e d e s c r ib e d a s a lo g ic a l
M ove (to a c q u ir e th e d a ta ); a lo g ic a l C o m p a re ( a g a in s t th e p r o f ile p ro v id e d
i n th e r e q u e s t ) ; a n d a lo g ic a l C a lc u la te (w hich i s a ch a n g e in v a lu e a c c o r d in g
to th e r u l e s p ro v id e d in th e re q u e s t).
A s y s t e m in l e v e l 3, o r a n y o th e r le v e l, m a y n o t a u to m a tic a lly in c lu d e a l l th e
m a n ip u la tio n f a c i l i t i e s c o n ta in e d in th e p r e v io u s le v e ls , b u t th e m a n ip u la tio n s it
c a n c a r r y o u t a r e m o r e s o p h is tic a te d . T h e A U T O M A P s y s t e m m a y b e c o n s id e r e d to b e in le v e l 3.
L ev el 4.
T h e f o u r th le v e l of c a p a b ilitie s i s th e r e s u l t of fo u r lo g ic a l o p e r a -
tio n s u s e d in s e q u e n c e , a n d th e s e p ro v id e th e m a n ip u la tio n f a c i li tie s of
c e n tr o id a llo c a tio n ( b e c a u s e m e a s u r e m e n t e f fe c tiv e ly h a s to b e done f ir s t)
a n d a u to m a tic c o n to u rin g .
T y p ic a l s y s t e m s w ith in le v e l 4 in c lu d e D IM E, O EM ,
SACS, F R IS , N O R D P L A N , a n d GRDSR.
J u s t a s . t h e r e a r e s e v e r a l w a y s of c a lc u la tin g a r e a o th e r th a n th e s in g le
a lg o r ith m m e n tio n e d in le v e l 3, t h e r e a r e s e v e r a l w a y s of c a lc u la tin g c e n tr o id s .
T h e c h o ic e an d e ffic ie n c y of p r o c e d u r e s f o r c a lc u la tin g a r e a s d ep e n d o n th e
m e th o d u s e d to s t o r e th e li n e s a s b o u n d a rie s of a r e a s w ith in th e c o m p u te r.
T h e d iff e re n c e b e tw e e n a p p r o a c h e s b y w h ich li n e s a r e r e p r e s e n t e d a s f o r m u la s
of c u r v e s , o r a s s tr a i g h t- li n e s e g m e n ts , o r a s c l o s e ly s p a c e d p o in ts o r s m a ll
g r id s , c a n b e r e a d i l y e n v isa g e d .
T h e c h o ic e of lin e s to r a g e m e th o d , and
h e n c e th e a p p ro a c h to a r e a c a lc u la tio n , i s d e p e n d e n t o n th e c h a r a c te r an d
v o lu m e of th e o r ig i n a l lin e d a ta , b a la n c e d a g a in s t th e n e e d to p r e s e r v e th e
a c c u r a c y o f th o s e d a ta a n d th e c o s t o f c o m p u te r p r o c e s s in g .
C e n tr o id d e t e r -
m in a tio n r e q u i r e s a n e x t r a c a lc u la tio n , th a t of d iv id in g th e to ta l m o m e n t b y
th e to t a l a r e a ; th e a d d itio n a l lo g ic a l C a lc u la te o p e r a tio n in v o lv ed p la c e s it in
200
le v e l 4.
T h e lo g ic a l o p e r a tio n s in v o lv ed a r e : a lo g ic a l M ove o r C o m p a re (to
a c q u ir e th e d a ta ); a lo g ic a l C a lc u la te (of th e s u b te n d e d a r e a an d m o m en t); a
lo g ic a l C a lc u la te (to s u m th e to ta ls ) ; an d a lo g ic a l C a lc u la te (to d iv id e th e
t o t a ls one in to th e o th e r to p ro v id e th e c o o rd in a te ).
A u to m a tic c o n to u r in g i s th e f a c ility of c r e a tin g is o lin e s th ro u g h a s e t of
p o in ts w ith v a r i a b le v a lu e s .
T h e s im p l e s t f o r m of a u to m a tic c o n to u rin g i s
th e p r o c e s s of s t a r t i n g a t a p o in t w ith a s p e c if ic v a lu e , o r a v a lu e w ith in a
s p e c if ie d r a n g e of v a lu e s , th e n jo in in g it to th e c l o s e s t p o in t w ith in th e s a m e
v a lu e r a n g e .
T h e r e a r e m o r e s o p h is tic a te d a p p ro a c h e s to a u to m a tic
c o n to u rin g , b u t th i s e le m e n ta r y one u s e s a m in im u m n u m b e r of lo g ic a l s te p s
a n d i s d e s c r i b e d to in d ic a te th e lo w e s t le v e l in th e h ie r a r c h y o f m a n ip u la tio n
f a c i l i t i e s a t w h ic h a u to m a tic c o n to u rin g b e c o m e s p o s s ib le .
A s s u m in g th a t th e p r o c e s s s t a r t s a t a g iv e n p o in t, th e s te p s r e q u i r e d a r e :
r e t r i e v a l of th e n e x t p o in t to b e c o n s id e re d ; d e te r m in a tio n of th e d is ta n c e
b e tw e e n th e g iv e n p o in t a n d th e n e x t p o in t; c o m p a ris o n of th e v a lu e o f th e n ex t
p o in t w ith a g iv e n s e t of r u le s to d e te rm in e if i t is th e c l o s e s t p o in t w ith in th e
s a m e r a n g e of v a lu e s , to c h e c k w h e th e r it h a s b e e n u s e d b e f o r e , an d to
e n s u r e th a t th e r e s u l t i n g c o n to u r w ill not c r o s s a n o th e r c o n to u r a lr e a d y in
e x is te n c e (though it c a n to u c h ); a n d f in a lly to jo in th e p o in ts b y a tta c h in g a
c o m m o n id e n tif i e r to th e new p o in t.
T h e lo g i c a l o p e r a tio n s n e e d e d a r e : a lo g ic a l M ove o r C o m p a re (to g e t th e n ex t
p o in t); a lo g ic a l C a lc u la te (to d e te rm in e th e d is ta n c e ); a lo g ic a l C o m p a re (w ith
a s e t of r u le s ) ; a n d a lo g ic a l M ove (to a s u b s e t, to a s s ig n a c o m m o n id e n tif ie r ) .
T h e r e l a t i v e s im p l ic i ty of th e s e t of r u le s in th e lo g ic a l C o m p a re i s th e
e s s e n t i a l d if f e re n c e b e tw e e n th is le v e l of m a n ip u la tio n a n d h ig h e r - le v e l m a n ip u la tio n s s u c h a s th e d e te r m in a tio n of in t e r v is ib i lit y b e tw e e n p o in ts.
In th e
l a t t e r c a s e , th e lo g ic a l C o m p a re w ould s p lit in to a lo g ic a l C o m p a re /M o v e
p ro c e ss.
SYM AP V a n d WWW, w ith t h e i r c a p a b ility f o r a u to m a tic c o n to u rin g ,
m a y a l s o b e c o n s id e r e d to b e a t le v e l 4.
L e v e l 5. T h e n e x t le v e l of c a p a b ilitie s i s th e r e s u l t of fiv e lo g ic a l o p e r a tio n s
u s e d in s e q u e n c e .
T h is p ro v id e s f a c i li tie s f o r th e s im p l e s t f o r m s of g e n e r a l i -
z a tio n , m e r g in g , d is s o lv in g , d e te rm in a tio n of in t e r v is ib i lit y , a n d s im u la tio n .
T y p ic a l o f th i s le v e l a r e s y s t e m s w ith f a c i li tie s f o r h il l sh a d in g o r r o u te
201
d e te rm in a tio n .
G e n e r a liz a tio n i s c o n s id e re d to b e th e p r o c e s s of c o m b in in g m u ltip le a r e a s ,
p o s s ib ly w ith m u ltiv a r ia b le c la s s if ic a tio n d e s c r i p t o r s , in to a s in g le l a r g e r
a r e a w ith a s in g le c la s s if ic a tio n .
T h e new c l a s s i f ic a t io n is b a s e d on th e
p r o p o r tio n of th e o rig in a l s e p a r a t e c l a s s i f ic a t io n s c o n ta in e d in th e new a r e a .
G e n e r a liz a tio n s of lin e s h a p e s s u c h a s c o a s tlin e s , a n d p a r t ic u l a r ly th e
" c o a s t a l is la n d " ty p e of p ro b le m , a r e a p p lic a tio n s of th e a lg o r ith m ; th i s w ill
b e o u tlin e d l a t e r .
T h e f i r s t p a r t of th e p r o c e s s i s to m e a s u r e th e s iz e of th e a r e a s to b e c o m b in e d , w h ic h is a r e p e a te d le v e l 3 o p e ra tio n .
T h e n e x t s te p i s to c o m p a r e
th e in f o r m a tio n c o n c e rn in g th e lo c a tio n an d s iz e o f th e a r e a s w ith a s e t of
ru le s .
T h e c o m p a ris o n w ill d e te r m in e if th e a r e a s f a l l in to a s iz e c a te g o r y
th a t r e q u i r e s th e m to b e g e n e ra liz e d an d , if th i s i s s o , w ith w h ic h a r e a s
a n d a c c o r d in g t o w h a t r u le s th e g e n e ra liz a tio n w ill ta k e p la c e .
F o r e x a m p le ,
i t m a y n o t b e p e r m itt e d to co m b in e c e r t a in ty p e s of c la s s if ic a tio n , s u c h a s
la n d a n d w a te r , o r , if s u c h a c o m b in a tio n is a llo w e d , a r e s u lt in g c la s s if ic a tio n
a s w a t e r m a y o r m a y not show th a t th e a r e a c o n ta in s a p e r c e n ta g e o f la n d .
T h e C o m p a re o p e ra tio n r e f l e c t s th e r u le s f o r g e n e r a liz a tio n th a t a p p ly in th e
p a r t i c u l a r c a s e a n d f o r m s th e b a s i s of th e c a lc u la tio n , w h ich fo llo w s th e
p re s c rib e d ru le s .
T h e f i r s t lo g i c a l o p e ra tio n in v o lv ed is a lo g ic a l M ove (to g e t th e d a ta ).
T h is
m a y in s te a d b e a lo g ic a l C o m p a re of th e g iv e n s t a r t i n g p o in t w ith th e b o u n d a ry
d e fin itio n , to d e te r m in e th e n e x t p o in t on th e b o u n d a ry .
T h is o p e r a tio n is
fo llo w e d b y a lo g ic a l C a lc u la te (of th e a r e a su b te n d e d ); a lo g ic a l C a lc u la te
(to c r e a t e th e to t a ls ) ; a lo g ic a l C o m p a re (w ith a s e t of r u le s ) ; a n d a lo g ic a l
C a lc u la te (a c c o rd in g to th e s e t of r u l e s , to p ro d u c e th e g e n e ra liz a tio n ) .
T h e c a s e of g e n e ra liz a tio n of is la n d s on a c o a s tlin e fo llo w s th e s a m e a lg o r ith m .
T h e s i z e o f th e is la n d s i s m e a s u r e d a s ab o v e.
T h e fo u rth s te p , th e lo g ic a l
c o m p a r is o n w ith a s e t of r u l e s , d e te r m in e s w h e th e r th e is la n d s a r e s m a l le r
th a n a p r e s c r i b e d m in im u m s iz e a n d c a n b e e lim in a te d ( r e p la c e d b y b la n k s)
d u r in g th e C a lc u la te o p e ra tio n ; w h e th e r th e y a r e l a r g e eno u g h to b e k e p t b u t
to o s m a l l f o r e a s y re c o g n itio n , in w hich c a s e th e s u b se q u e n t C a lc u la te
202
e n l a r g e s th e m ; o r w h e th e r th e y a r e s o la r g e th a t g e n e ra liz a tio n i s not
d e s ir a b le .
If th e p r e s c r i b e d s iz e li m it s in th e r u le s w e re s e t a t a s u ita b ly
low le v e l, th e C a lc u la te o p e r a tio n c o u ld m a k e P r i n c e E d w a rd Is la n d th e
s iz e of G re e n la n d .
M e rg e i s th e p r o c e s s of co m b in in g co n tig u o u s a r e a s th a t q u a lify f o r
in c lu s io n in a g iv e n new c a te g o ry o r s e t of c a te g o r ie s , a s d e fin e d u n d e r
m a n u a l p r o c e d u r e s in C h a p te r 3 a n d in th e CGIS d e s c r ip tio n in th e A pp en d ix .
T h e p r o c e s s is i l l u s t r a t e d in F ig . 6. 5.
C ase 1
M e rg e w o u ld o c c u r h e r e
B
C
X
X
X
A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
A
X
X
B
X
X
X
X
X
X
X
X
B
C
X
A
M ap sh o w in g 1 - m ile s q u a r e f ie ld s o f la n d
c la s s if ie d a c c o r d in g
to q u a lity .
C ase 2
M e rg e w o u ld o c c u r h e r e
G iven th a t la n d ty p e s A , B , an d C a r e p rim e la n d , an d
i t i s r e q u i r e d to d e te r m in e th e s iz e a n d n u m b e r o f p ie c e s
of p r im e la n d on th e m a p , th e a n a ly s is w o u ld p ro v id e th e
a n s w e r th a t th e r e w e r e fiv e p ie c e s of p r im e la n d , o n e of
3 s q u a r e m i le s , one of 2 s q u a r e m i le s , an d th e r e m a in d e r
of 1 s q u a r e m ile . T h e M e rg e f a c i li ty w o u ld b e u s e d in
c a s e s 1 a n d 2.
F ig . 6. 5.
E x a m p le of th e m e rg e p r o c e s s .
T h e M e rg e f a c i li ty w ould b e u s e d f o r a l l c o n tig u o u s o c c u r r e n c e s o f la n d
ty p e s A , B , an d C in th e f ig u r e , s u c h a s in C a s e 1 and C a s e 2, to co m b in e
t h e i r p ie c e s f o r m e a s u r e m e n t an d to a s s ig n th e r e s u lt in g p ie c e s to th e c a t e g o r y " p r im e la n d " .
T h is p r o c e s s i s s i m i l a r to g e n e ra liz a tio n in it s lo g ic a l
p a th , b u t i s s lig h tly d iffe re n t in a p p lic a tio n .
T h e f i r s t p a r t of th e p r o c e s s is to c a lc u la te th e s iz e of th e a r e a s to b e
203
c o n s id e re d .
(A lthough th e c a lc u la tio n i s p a r t of th e lo g ic a l p r o c e s s , it m a y
h a v e b e e n done a t a n e a r l i e r s ta g e in s o m e s y s t e m s , s u c h a s CGIS; th is
s h o r te n s th e s u b s e q u e n t M e rg e p r o c e s s an d m a k e s it m o re e f f i c ie n t .) T h e
in fo r m a tio n d e s c r ib in g th e s e a r e a s i s c o m p a re d w ith a s e t o f r u l e s , to
d e te r m in e if th e c l a s s i f ic a t io n s a r e of a ty p e th a t ca n b e m e r g e d a n d if th e y
a r e c o n tig u o u s w ith s i m i l a r a r e a s .
T h is le a d s to th e c a lc u la tio n in w h ich
th e s iz e s of th e a r e a s to b e m e rg e d a r e s u m m e d .
T h e s e q u e n c e of lo g ic a l o p e r a tio n s is : M ove, C o m p a re , an d C a lc u la te
o p e r a tio n s (to m e a s u r e th e a r e a s ) ; a lo g ic a l C o m p a re (a g a in s t a s e t o f r u le s ) ;
a n d a lo g ic a l C a lc u la te (to a d d th e t o t a ls a n d c r e a te th e new c o m b in e d a r e a s ) .
D is s o lv e i s th e p r o c e s s of re m o v in g a co m m o n b o u n d a ry b e tw e e n s p e c if ie d
a r e a s an d g ro u p in g th e m in to a co m m o n a r e a .
of tw o s p e c if ie d a r e a s .
It i s s im p ly a s in g le m e r g in g
T h e p r o c e s s of D is so lv e a n d th e p r o c e s s o f M erg e
a r e id e n tic a l, e x c e p t th a t th e a p p lic a tio n of th e D is so lv e to th e a c tu a l im a g e
in c lu d e s in i t s c a lc u la tio n th e r e m o v a l of th e id e n tifie d b o u n d a ry a n d th e r e c a l c u la tio n of th e v a lu e s of p o in te r s on th e s e g m e n ts , a s d ir e c te d b y th e s e t of
r u le s .
T h e c o n c e p t of d e te r m in in g in t e r v is ib i lit y b e tw e e n g iv e n p o in ts i s s t r a i g h t fo rw ard .
T h e a im is to f in d out if a n y in te r m e d ia te p o in t on a lin e b e tw e e n
tw o g iv e n p o in ts h a s a h ig h e r a ltitu d e th a n th e p la n e on w h ich th e y a r e
lo c a te d (F ig . 6. 6).
I n te r v is ib il ity lin e
Z a x is
X , Y p la n e
F ig . 6. 6.
I n te r v is ib il ity b e tw e e n g iv e n p o in ts.
T h e s te p s in th e p r o c e s s a r e to r e t r i e v e th e d a ta ; to c a lc u la te th e c o o r d in a te
on th e X , Y p la n e of th e n e x t p o in t (o b s tru c tio n ) to b e p r o c e s s e d ; to c a lc u la te
th e Z c o o r d in a te of th e in te r s e c tio n ; to c o m p a re th e r e s u l t s w ith a s e t of
r u le s to d e te r m in e if th e n ex t p o in t is c lo s e enough to th e in te r v is ib i lit y lin e
204
to b e c o n s id e r e d , an d if s o i f i t s Z c o o r d in a te v a lu e i s h ig h e r th a n th a t o f th e
in t e r s e c ti o n ; a n d to m o v e a n id e n tif ie r to a s s ig n a v a lu e to th e in t e r v is ib i lit y
lin e if th e c o m p a r is o n sh o w s th a t i t i s e q u a l o r h ig h e r.
T h e lo g ic a l o p e r a tio n s a r e : a lo g ic a l M ove (to g e t th e d ata); a lo g ic a l C a lc u la te
(to d e te r m in e th e d is ta n c e aw ay f r o m th e lin e b e tw e e n th e tw o p o in ts); a lo g ic a l C a lc u la te (of th e h e ig h t of th e in t e r v is ib i lit y lin e a t th a t p o in t); a lo g ic a l
C o m p a re ( a g a in s t a s e t of r u le s ) ; an d a lo g ic a l M ove (to id e n tify th e lin e ).
In th e s im p l e s t t e r m s , S im u la tio n is th e p r o c e s s o f ta k in g s t a t i s t i c s an d
e x tr a p o la tin g t r e n d s f r o m th e m u n d e r c e r t a in c o n s tr a in ts an d p r o b a b ilitie s .
T h is is a v e r y b a s i c v ie w p o in t of a p r o c e s s th a t c a n b e e x tr e m e ly co m p lex .
S im u la tio n d if f e r s f r o m th e m a n ip u la tio n s d e s c r ib e d s o f a r , in th a t th e o th e r s
a r e e s s e n ti a ll y s e t s of p re d e fin e d o p e ra tio n s in a s p e c if ie d s e q u e n c e , w h e r e a s
e a c h s im u la tio n i s a u n iq u e in t e r p r e ta tio n a p p lie d to e a c h s e t o f d a ta .
To
a c h ie v e a n o p tim u m s im u la tio n f o r a p a r t ic u l a r p u rp o s e , one m u s t c r e a te a
s p e c i a l s e t o f o p e r a tio n s th a t p ro d u c e s th e d e s ir e d r e s u l t f o r th e s p e c ific
d a ta s e t .
D e fin in g th e a lg o r ith m is p a r t of th i s p r o c e s s .
F o r th e s a k e of
e c o n o m y , p r e s p e c i f ie d s im u la tio n m o d e ls a r e o fte n u s e d on v a r io u s s e t s of
d a ta , b u t th i s u s u a lly r e q u i r e s a s a c r i f i c e to g e n e ra lit y an d a c o m p ro m is e in
s o m e s p e c if ic a s p e c t s of th e p ro b le m s to b e so lv ed .
T h e b a s ic a p p r o a c h to s im u la tio n c a n b e th o u g h t of
in th e fo llo w in g s te p s .
F i r s t , th e s t a t i s t i c s th a t d e s c r ib e th e c o n s tr a in ts an d th e p r o b le m h av e to b e
g a th e r e d to g e th e r .
T h e s e c o n d s te p is th e g e n e ra tio n of a n a lg o r ith m
(fo rm u la ) to r e p r e s e n t th o s e s t a t i s t i c s .
T h e t h i r d i s th e g e n e ra tio n o r s e l e c -
tio n of p r o b a b i lit ie s o r p r o b a b ility d is tr ib u tio n s th a t w ill b e s t r e p r e s e n t th e
s t a t i s t i c a l t r e n d s p ro v id e d in th e d a ta g a th e r e d in s te p o ne.
T h e fo u rth i s to
a p p ly th e p r o b a b i lit ie s to th e fo r m u la , to g e n e r a te th e f o r e c a s te d r e s u lt .
The
lo g i c a l o p e r a tio n s n e e d e d to a c h ie v e th e s e s te p s a r e : a lo g ic a l M ove (to a c q u ir e
th e d a ta ); a lo g ic a l C o m p a re (a g a in s t a p r o f ile p ro v id e d in th e re q u e s t); a
lo g ic a l C a lc u la te (a c c o rd in g to th e r u l e s in th e r e q u e s t); a lo g ic a l C a lc u la te (to
g e n e ra te th e a p p lic a b le p ro b a b ilitie s ) ; a n d a lo g ic a l C a lc u la te (to ap p ly
p r o b a b i lit ie s to th e fo r m u la , to g e n e ra te th e f o r e c a s t e d r e s u lt s ) .
D ep en d in g on th e a lg o r ith m th a t h a s b e e n d e v e lo p e d , th e fin a l s te p is a c tu a lly
th e " s im u la tio n " s te p .
205
L e v e l 6. T h e s e c o n d m a jo r c a te g o ry of m a n ip u la tio n f a c i li tie s c o n ta in s th o s e
th a t in c o r p o r a te o v e r la y (s e e F ig . 6. 4 ), a n d le v e l 6 i s a r b i t r a r i l y o c c u p ie d
b y th e o v e r la y f a c i li ty it s e lf .
O v e rla y i s th e w e ll-u n d e r s to o d a b ility to
s u p e r im p o s e tw o m a p s (th a t i s , tw o s e t s of im a g e s an d c la s s if ic a tio n s y s te m s )
a n d s e n s ib ly co m b in e th e m in to o n e m a p (th a t i s , in to o n e im a g e a n d o ne
c la s s i f ic a t io n s y s te m ) .
T h e g e n e ra l p r in c ip le s of th e m a tic m a p o v e r la y w ill
b e d e s c r ib e d b elo w , a n d alth o u g h t h e r e a r e s e v e r a l a p p ro a c h e s to th e t a s k ,
th e one u s e d in CGIS w ill p ro v id e e x a m p le s w h e r e d e ta ils o f a s p e c if ic
a l g o r ith m a r e g iv en .
A p r e l im i n a r y s te p in th e p r o c e s s of o v e r la y is to s e le c t th e p a r t i c u l a r p a r t s
o f th e tw o m a p s th a t h a v e to b e o v e r la id , in o th e r w o r d s , to d efin e th e s u b s e ts
o f th e to t a l a r e a th a t h av e to b e o v e r la id .
o v e r l a id o n M ap A.
F ig . 6. 7 sh o w s M ap B p a r t ia l ly
T h e d e c is io n m u s t b e m a d e w h e th e r to in c lu d e in th e
o u tp u t a l l p o r tio n s th a t a r e co m m o n to A an d B. (A∩B ), o r to in c lu d e a l l a r e a s
of b o th A a n d B (A⋃B).
In th e l a t t e r c a s e , a n a r b i t r a r y n u ll c l a s s i f ic a t io n
c o u ld b e u s e d f o r th e p o r tio n of th e r e s u lt in g o v e r la y th a t d o e s n o t o v e rla p ;
in th e CG IS, c h a r a c t e r b la n k s a r e a s s ig n e d .
A f u r t h e r c h o ic e i s to o v e r la y
o n ly c e r t a i n p o rtio n s of th e in t e r s e c ti o n of A a n d B.
2 M aps
A
B
F ig . 6. 7.
O v e rla y c o n d itio n w h e re M ap B i s p a r t ia l ly o v e r la id o n M ap A.
T h e f i r s t s te p in th e a c tu a l o v e r la y p ro c e d u r e i s to la y o u t th e im a g e o f th e
f i r s t m a p in m e m o ry .
T h e im a g e of th e s e c o n d c o v e ra g e i s th e n la id o v e r
th e f i r s t im a g e in m e m o ry .
D u rin g th i s p r o c e s s th e im a g e s a r e c o m p a r e d ,
p o in t b y p o in t, f o r in t e r s e c ti o n s of b o u n d a r ie s an d f o r e a c h in t e r s e c ti o n p o in t
fo u n d , a v a lu e (th e X , Y c o o rd in a te of th e in te rs e c tio n ) i s p u t in to a ta b le .
N ex t, t h e ta b le of in t e r s e c ti o n s i s s o r t e d in to a c o n v e n ie n t s e q u e n c e f o r
206
s u b s e q u e n t c o m p a r is o n s ; in th e CGIS a p p ro a c h th e ta b le is o r d e r e d b y X, Y
v a lu e s .
T h e n u m b e r of b o u n d a ry in t e r s e c ti o n s s o s to r e d is th e o r e tic a lly
in f in ite , an d is lim ite d o n ly by th e c a p a c ity of th e m e m o ry s y s t e m an d th e
f a c t th a t a m e a n in g le s s q u a n tity of in t e r s e c ti o n s m a y b e c r e a te d w h en
n u m e r o u s c o v e ra g e s a r e s o o v e r la id .
T h e CGIS d e s ig n h a s a r b i t r a r i l y s e t
e ig h t m e d iu m - o r lo w -d e n s ity m a p c o v e ra g e s a s i t s u p p e r li m it .
T h e o v e r la y
o f tw o m a p c o v e ra g e s w ith e x tr e m e ly d e n s e b o u n d a ry s e t s c a n c a u s e p r o b le m s
w ith m e m o r y c a p a c ity a t th i s p o in t in th e p r o c e s s .
T h e n e x t o p e r a tio n i s to r e - e x a m in e e a c h of th e tw o c o v e ra g e s b e in g o v e r l a id
a n d to b r e a k up t h e i r b o u n d a r ie s in to s u b s e g m e n ts w h o se e n d s a r e th e s a m e
a s th e n ew ly d e te rm in e d in t e r s e c ti o n p o in ts .
T h e s u b s e g m e n ts a r e th e n
re c o n n e c te d to c r e a te th e new a r e a s a n d s o c o m p le te th e o v e r la y o f th e im a g e s ,
T h is l a s t s te p m u s t b e done s e n s ib ly w ith r e g a r d to th e c la s s if ic a tio n s
a tta c h e d to th e p r e v io u s b o u n d a rie s .
S y s te m s do n o t n e c e s s a r i l y k e e p t h e i r im a g e an d d e s c r i p t o r d a ta s e t s in
d if f e re n t f i l e s , a s in CGIS, an d th e co m b in in g of a r e a s an d c la s s if ic a tio n
s y s t e m s s o m e tim e s p ro c e e d s s im u lta n e o u s ly .
S im ila r ly , t h e r e a r e d if f e re n t
a p p r o a c h e s to th e p r o c e s s o f co m b in in g th e c l a s s i f ic a t io n s f r o m tw o o r m o re
m a p s to p ro d u c e th e c la s s if ic a tio n f o r th e new m a p .
em p lo y e d .
G e n e r a liz a tio n m a y b e
In co m b in in g 12 w e a th e r m a p s , e a c h sh o w in g th e a v e ra g e m e an
t e m p e r a t u r e f o r a m o n th o f th e y e a r , one m a y w is h to p ro d u c e an e n d r e s u l t
s h o w in g a r e a s w ith a s p e c if ic p r o f ile o f t e m p e r a t u r e , f o r e x a m p le , a n a r e a
th a t e n jo y e d 30% of th e y e a r b e tw e e n 30 a n d 40º F , 40% of th e y e a r b e tw e e n
40 a n d 7 0 ° F , a n d 30% of th e y e a r b e tw e e n 70 an d 9 0 ° F .
T h is ty p e of ch an g e
in c l a s s i f ic a t io n c o u ld b e h a n d le d b y th e im a g e o v e r la y p r o c e s s d e s c r i b e d
a b o v e , b u t th e g e n e ra liz a tio n of th e d e s c r i p to r d a ta w o u ld h a v e to follow a
c o m p le x s e t of r u le s th a t w o u ld d ep e n d to a g r e a t e x te n t o n th e f o r m a t an d
n a t u r e o f th e d a ta .
T h e CGIS a p p ro a c h is to u s e s im p le c o n c a te n a tio n o f th e
d e s c r i p t o r d a ta s e t s , s o th a t th e d e s c r i p to r of e a c h new a r e a f o r m e d b y th e
o v e r l a y is o b ta in e d b y s im p ly a d d in g to g e th e r th e c la s s if ic a tio n s o f th e tw o
o r ig i n a l a r e a s .
d e p e n d e n t.
T h e p r o c e s s fo llo w s a s im p le s e t of r u le s an d i s n o t d a ta
T h e to t a l c l a s s i f ic a t io n of o n e a r e a i s c o m b in e d w ith th e to t a l
c l a s s i f ic a t io n of th e o v e rly in g a r e a .
T h e r e a r e , of c o u r s e , v a r ia tio n s in
207
th e a p p ro a c h to o v e r la y , d ep e n d in g on th e n a tu r e of th e c o m p u te r b e in g u s e d ,
th e s iz e of th e r e c o r d s b e in g h a n d le d , an d th e r e s u l t s r e q u ir e d b y th e u s e r .
T h e lo g ic a l o p e r a tio n s in v o lv ed in p r e l im i n a r y s e le c tio n of th e a r e a s to b e
o v e r la id a r e : a lo g ic a l M ove (to g e t th e d a ta ); a lo g ic a l C o m p a re (a g a in s t a
s e t of r u l e s ) ; a n d a lo g ic a l M ove (to a s u b s e t).
In th e b a s ic ty p e o f o v e r la y
p r o c e s s , th e lo g ic a l o p e ra tio n s b e g in w ith a lo g i c a l M ove ( fro m a u x ilia r y
s to r a g e to m e m o ry ) to la y o u t th e im a g e o f th e f i r s t c o v e ra g e ; th e s e c o n d
im a g e i s la i d o u t a n d th e s u b s e q u e n t c o m p a ris o n a n d fo rm a tio n o f th e ta b le
of in t e r s e c ti o n s a r e done b y a r e p e a te d lo g ic a l M ove an d lo g ic a l C o m p a re ,
fo llo w e d b y a lo g ic a l M ove (of th e id e n tifie d in t e r s e c ti o n s to th e ta b le ) .
The
ta b le i s s o r t e d in to s e q u e n c e b y a c y c le c o n s is tin g of a lo g ic a l C o m p a re
fo llo w e d b y a lo g ic a l M ove.
T h e e x is tin g b o u n d a r ie s a r e b ro k e n dow n in to
s u b s e g m e n ts b y a lo g ic a l M ove (w ithin th e im a g e d a ta ), a lo g ic a l C o m p a re
(w ith th e a l r e a d y s e q u e n c e d in t e r s e c ti o n ta b le ), a n d a lo g ic a l M ove (of th e
d a ta s u b s e g m e n ts to s to r a g e w h en th e n e x t in t e r s e c ti o n is r e a c h e d ) .
T he
s u b s e g m e n ts a r e re c o n n e c te d in to a r e a s b y a lo g ic a l C o m p a re (to m a k e s u r e
th a t i t i s a n o th e r s e g m e n t b o u n d in g th e s a m e a r e a ) an d a lo g ic a l M ove to
r e d i r e c t th e p o in t e r s .
L e v e ls 7 to 11. T h e s e q u e n c e o u tlin e d ab o v e w a s ta k e n m a in ly f r o m th e
p r o c e s s of im a g e o v e r la y u s e d in th e CG IS, a n d 11 lo g ic a l o p e r a tio n s w e r e
id e n tifie d in i t .
A n o v e r la y p r o c e s s b a s e d on im a g e s alo n e co u ld ta k e s o m e -
w h a t fe w e r lo g ic a l o p e r a tio n s , b u t a t th e e x p e n s e of p r o c e s s in g ti m e , o r if
b a s e d on a l e s s c o m p le x d a ta s tr u c t u r e .
O ne w ith m o re s o p h is tic a te d
h a n d lin g of c o m p le x im a g e c o n d itio n s o r of d e s c r i p to r d a ta co u ld h a v e m o r e
o p e r a tio n s .
A s th e o v e rla y m a n ip u la tio n i s c o n s id e re d to b e s ig n if ic a n tly
m o r e c o m p le x th a n th e m a n ip u la tio n s d e s c r ib e d in le v e ls 1 to 5, it h a s b e e n
a r b i t r a r i l y a s s ig n e d to le v e l 6 a n d f o r m s th e b a s i s of th e s e c o n d c a te g o r y .
T h e le v e ls d e s c r i b e d in th e f i r s t c a te g o ry c a n b e r e p e a te d a s le v e ls in th e
s e c o n d c a te g o r y (w ith th e a d d itio n of an a r b i t r a r y s ix o p e ra tio n s o n th e f r o n t
of e a c h m a n ip u la tio n ), p ro v id in g le v e ls 7 th ro u g h 11.
L e v e l 8 i s th u s a s y s t e m w ith o v e r la y c a p a b ilitie s th a t c a n a ls o c a r r y out
m a n ip u la tio n s up to le v e l 2 , e i th e r b e f o re o r a f t e r th e o v e r la y m a n ip u la tio n .
208
L e v e l 9 in c o r p o r a te s o v e r la y c a p a b ility w ith in th e f a c i l i t i e s o f le v e l 3, an d is
ty p ic a lly r e p r e s e n t e d b y th e P IO S , M A P /M O D E L , N RIS, an d GIMMS s y s te m s .
L e v e ls 12 to 24. T h e t h i r d m a jo r c a te g o ry in c o r p o r a te s a l l s y s te m s w ith a
m o n ito r s y s t e m o r q u e r y la n g u a g e , o r b o th , th a t h a v e b e e n d e v e lo p e d o r
im p le m e n te d to a s ig n ific a n t d e g re e .
T h is f a c i li ty m a y e x i s t w ith o r
w ith o u t th e o v e r la y c a p a b ility an d , u s in g a b a s e of 12, p ro v id e s le v e ls 13 to
24.
I ts p o s itio n on th e a x is (s e e F ig . 6 .4 ) th u s n e e d n o t b e a li n e a r p r o g r e s -
s io n f r o m th e o v e rla y ; it is p la c e d t h e r e m e r e ly f o r c o n v e n ie n c e , an d p e r h a p s
to in d ic a te th e s ig n ific a n tly h ig h le v e l o f c a p a b ility f o r m a n ip u la tio n .
The
s e q u e n c e of le v e ls c o u ld b e c o n tin u e d th ro u g h th i s t h i r d c a te g o r y to in d ic a te
th e r e l a ti v e s o p h is tic a tio n of c a p a b ility f o r m a n ip u la tio n .
A lth o u g h th e p o s i -
tio n of s y s te m s w ith m o n ito rin g c a p a b ilitie s on th e a x is is a r b i t r a r y , in p r a c ti c e th e y h av e n o t b e e n c o n s id e re d n e c e s s a r y f o r s y s t e m s w ith r e l a ti v e ly
s im p le m a n ip u la tio n f a c i li tie s .
O nly th e h i g h e r - o r d e r s y s t e m s in c o r p o r a tin g
o v e r la y o r in te r a c tiv e p r o c e s s e s , o r b o th , e m p lo y th i s in c r e a s e d le v e l of
s o p h is tic a tio n .
T h e p r o g r e s s io n of m a n ip u la tio n f a c i l i t i e s a lo n g th e a x is th u s
r e p r e s e n t s a r e l a ti v e ly c l e a r p r o g r e s s io n of a c tu a l c a p a b ilitie s f o r m a n ip u la tio n in s y s t e m s in 1974.
A m o n ito r s y s t e m a n d q u e ry la n g u a g e f a c i li ty i s n o t a n o p e r a tio n in its e lf ;
r a t h e r , i t i s a n o v e r a l l c o n tro llin g fu n c tio n of o th e r o p e r a tio n s .
A m o n ito r
s y s t e m i s th e e x e c u tiv e d ir e c to r of n o r m a l o p e r a tio n s w ith in th e c o m p u te r
a n d i t s p u r p o s e is to f r e e th e o p e r a to r f r o m m a n u a l c o n tr o l t a s k s ; it m a k e s it
a s e a s y a s p o s s ib le f o r th e u s e r to h a v e h is r e q u e s t a n s w e r e d .
A q u e ry
la n g u a g e i s a s e t of code w o rd s u s e d to s p e c ify th e m a n ip u la tio n a n d r e t r i e v a l
fu n c tio n s r e q u ir e d .
O ne of th e b a s ic fu n c tio n s of th e m o n ito r s y s t e m is
a u to m a tic a lly to co m b in e m a n ip u la tio n o r r e t r i e v a l c o m m a n d s f r o m th e q u e ry
la n g u a g e w ith th e d e s c r ip tiv e in fo rm a tio n in th e a p p r o p r ia te f i l e s , and
w ith c o m p u te r p r o g r a m s r e s id e n t in th e s y s t e m l i b r a r i e s .
I t th u s g e n e r a te s
a c o m p le te r e q u e s t th a t th e c o m p u te r c a n u s e to e n t e r th e d a ta b a n k , p ro d u c e
th e d e s ir e d m a n ip u la tio n , an d p r e s e n t i t s r e s u l t s in ta b u la r o r p lo tte d fo r m .
A fu ll te c h n ic a l d e s c r ip tio n of a ty p ic a l m o n ito r s y s t e m a n d q u e r y la n g u ag e
i s g iv e n f o r th e CGIS in th e A ppendix.
T h e lo g ic a l o p e ra tio n s in v o lv ed in th e b a s ic th e o r e ti c a l a p p ro a c h u s e d b y th e
209
m o n ito r s y s t e m a n d q u e ry la n g u a g e a r e a s fo llo w s : a lo g ic a l M ove (to r e a d
th e a tte n tio n s ig n a l f r o m th e in p u t d e v ic e ); a lo g ic a l M ove (to s e n d a c k n o w le d g e m e n t to th e d e v ic e ); a lo g ic a l M ove (to r e a d th e in itia liz a tio n r e c o r d
f r o m in p u t o r o u tp u t of th e l a s t c o m p le te d ta s k ) ; a lo g ic a l C o m p a re (to
c h e c k th e v a lid ity of th e u s e r , o r a g a in s t th e ta b le of a c tiv e ta s k s ) ; a lo g ic a l
M ove (of a m e s s a g e to th e t e r m i n a l te lli n g i t to e n te r th e r e q u e s t , i f th e
r e q u e s t is f r o m a te r m in a l, o r to r e m o v e th e t a s k id e n tif ie r f r o m th e ta b le
o f a c tiv e ta s k s ) ; a lo g ic a l M ove (to r e a d th e f i r s t lin e of th e r e q u e s t , o r , if
th i s i s th e l a s t s te p of th e p r o c e s s , to r e t u r n to w a itin g s ta tu s ) ; a lo g ic a l
C o m p a re (of k e y w o rd w ith l i s t , to e d it th e k e y w o rd f o r v a lid ity ); a lo g ic a l
M ove (to r e a d f il e d e fin itio n s on a s p e c i a ll y d e s ig n e d s y s t e m f il e a s s o c ia te d
w ith th e m o n ito r to d e te r m in e th e f i l e s a s s o c ia te d w ith th e p r o g r a m ); a
lo g ic a l M ove (to c a ll in th e o p tio n a l p a r a m e t e r s p ro v id e d in th e r e q u e s t to
m o d ify th e f ile d e fin itio n , f o r e x a m p le , th e n a m e s of th e c o v e ra g e s to b e
a c c e s s e d ) ; a lo g ic a l M ove (to lo a d th e p r o g r a m f r o m th e l i b r a r y to th e
c o m p u te r); a lo g ic a l M ove (to e n t e r th e ta s k id e n tif ie r in to th e ta b le of
a c tiv e ta s k s ) ; a lo g ic a l M ove (to h a n d o v e r c o n tr o l of p r o c e s s in g to th e
p ro g ra m , an d s o in i tia te th e t a s k , a n d th e n r e t u r n to w a itin g s ta tu s ) ; a n d a
lo g ic a l M ove, C o m p a re , M ove, C a lc u la te , a n d M ove s e q u e n c e (s e e q u e r y
la n g u a g e ).
T h e a b o v e lo g ic a l s te p s a r e th e n r e p e a te d a s n e c e s s a r y .
T h e o n ly s y s t e m know n to h a v e a f u ll m o n ito r s y s t e m in co n ju n c tio n w ith
o v e r la y an d a l l lo w e r - l e v e l c a p a b ilitie s f o r m a n ip u la tio n i s th e CG IS, w h ich
w o u ld h a v e an a p p r o x im a te le v e l o f 22.
T h e USGS s y s te m , 1 now in th e
e x p e rim e n ta l p h a s e , an d d e v e lo p m e n ts of th e U. S. E n g in e e r s W a te rw a y s
s y s t e m 2 a n tic ip a te a tta in in g th i s le v e l of m a n ip u la tio n fa c ility .
T h e ab o v e d is c u s s io n of m a n ip u la tio n f a c i l i t i e s h a s b e e n m o r e e x te n s iv e th a n
th o s e f o r th e a x e s of lo c a tio n id e n tif i e r a n d v o lu m e of r e l a te d d a ta , m a in ly
b e c a u s e th e te c h n iq u e s in v o lv e d h a v e n o t b e e n c l a s s i f ie d b e f o r e a n d it w a s
n e c e s s a r y to e s ta b lis h s o m e b a s i s f o r c o m p a ris o n , h o w e v e r b r o a d an d
s im p l is tic .
T h e c a te g o r ie s a n d s u b c a te g o r ie s id e n tifie d (s e e F ig . 6 .4 ) a r e
n o t li n e a r l y d is tr i b u te d a lo n g th e a x is .
T h e r e a r e o b v io u s d is c o n tin u tie s of
s c a le am o n g th e t h r e e m a in c a te g o r ie s , an d th e d is tr ib u tio n i s n o t a r ith m e tic
b u t te n d s to b e lo g a r ith m ic in t e r m s of th e i n c r e a s e in c o m p le x ity of
1. E d s o n 1973.
2. L a G a rd e 1973.
210
m a n ip u la tio n a lo n g th e a x is .
A m o re d e ta ile d e x a m in a tio n o f th e p r o c e s s e s
w o u ld p ro b a b ly r e v e a l th a t th e p r o g r e s s io n w a s m u lti-d im e n s io n a l.
F o r th e
p u r p o s e s of th i s d is c u s s io n , h o w e v e r, th e a x is p r o v id e s a s im p le e m p ir ic a l
s u m m a r y of th e r e l a ti v e le v e ls of m a n ip u la tio n c a p a b ility in s y s te m s .
SYNTHESIS
T h e fo llo w in g s e r i e s of d ia g r a m s il l u s t r a t e s th e lo c a tio n of th e v a r io u s
s y s t e m s in r e l a ti o n to th e a x e s d e s c r ib e d ab o v e.
N in e te e n s y s t e m s h a v e b e e n lo c a te d on th e fo llo w in g d ia g r a m s .
N ot a l l th e
s y s t e m s m e n tio n e d in th e p re v io u s c h a p te r s h a v e b e e n p lo tte d , a s th i s w o u ld
h a v e in c u r r e d m a n y c l o s e ly o v e rla p p in g n a m e s an d u n n e c e s s a r y d u p lic a tio n .
(T he SYM AP s y s te m , f o r e x a m p le , i s r e p r e s e n t a ti v e of a p p r o x im a te ly te n
s i m i l a r s y s t e m s th a t w o u ld e a c h o cc u p y a p p ro x im a te ly th e s a m e s p a c e o n th e
d i a g r a m .) H o w e v e r, e a c h s y s t e m p r e v io u s ly m e n tio n e d in th e te x t a s an
e x a m p le of a p a r t i c u l a r c a te g o r y of s to r a g e f o r m a t is p lo tte d .
W h e re s p a c e
p e r m itt e d , a n d d if f e re n c e s w a r r a n te d , o th e r s y s t e m s h av e b e e n a d d e d .
The
M in n e s o ta (MINN) s y s te m , w h ich u s e s 4 0 - a c r e g r id u n its , h a s b e e n p lo tte d
a s w e ll a s th e LU N R s y s te m , w h ich u s e s l- k m 2 u n its .
The "C ensus"
s y s t e m r e p r e s e n t s t r a d iti o n a l, c o m p u te r-a id e d , c e n s u s h an d lin g te c h n iq u e s
u s e d p r i o r to th e a d v e n t of th e GRDSR a n d D IM E ty p e of s y s te m s , a n d w h ich
s t i l l a c c o u n t f o r th e g r e a t e s t am o u n t of c e n s u s d a ta h a n d lin g .
T h e w o rld -w id e
w e a th e r (WWW)1 s y s t e m , w h ic h i s e s s e n ti a ll y a p o in t d a ta s y s te m , h a s b e e n
sh o w n a s it r e p r e s e n t s th e l a r g e s t n u m e r ic a lly co d e d , lo c a tio n - s p e c if ic d a ta
s e t c u r r e n t ly b e in g h a n d le d .
M anual te c h n iq u e s a r e n o t id e n tifie d a s th e y
a r e not tr a d iti o n a ll y re c o g n iz e d a s s y s te m s .
T h e ir c o n trib u tio n to o v e r a ll
d a ta h a n d lin g c a p a b ility w ill, h o w e v e r, b e c o m e a p p a re n t.
T h e f i r s t d ia g r a m (F ig . 6. 8) lo c a te s th e 19 s y s t e m s in th e r e c o r d p la n e ,
w ith r e s p e c t to th e v a r i a b le s of lo c a tio n id e n tif i e r a n d v o lu m e o f r e l a t e d
d a ta . .T h is p e r h a p s i s th e m o s t in t e r e s ti n g of th e t h r e e v ie w s o f th e cube
sh o w n , a s i t g iv e s a n o v e r a l l p ic tu r e of th e g e n e ra l a v a ila b ility o f s y s te m s
( r e g a r d l e s s of m a n ip u la tio n c a p a b ility ) to h a n d le v a r io u s ty p e s o f d a ta .
1. P e r s o n a l c o m m u n ic a tio n , M cK ay 1973.
Location
ide ntifie rs
211
Volume
F ig . 6. 8.
of related da ta
L o c a tio n id e n tif i e r s r e l a t e d to v o lu m e of r e l a te d d a ta .
T h e a r e a of th e d ia g r a m c l o s e s t to th e o r ig in of b o th a x e s c o n ta in s no
c o m p u te r - a id e d s y s t e m s .
In th is a r e a of s im p le lo c a tio n id e n tif i e r s an d
r e l a ti v e ly low v o lu m e s of r e l a te d d a ta , c u r r e n t m a n u a l te c h n iq u e s o f s to r in g
a n d a n a ly s in g d a ta a r e e c o n o m ic a l an d s a ti s f a c to r y to th e u s e r .
Im m e d ia te ly b e y o n d th i s a r e a i s a p r o li f e r a ti o n of c u r r e n t w o rk in g s y s t e m s ,
lo c a te d a c c o rd in g to t h e i r n e e d to h a n d le im a g e s in r e l a te d d a ta s e t s .
The
v a r io u s a r b i t r a r y r e g u l a r - a r e a g r id s y s te m s su c h a s SYM A P, M IADS1, MINN,
a n d LUNR a r e r e p r e s e n t e d h e r e , a s a r e th e p o in t d a ta s y s t e m s of GRDSR
a n d F R IS .
T h e s e s y s te m s a r e r e a s o n a b l y w e ll e s ta b lis h e d in c u r r e n t p r a c t ic e , b u t it is
1. A m idon 1964, 1966.
212
in t e r e s ti n g to n o te th a t a s in c r e a s in g v o lu m e s of d a ta a r e h a n d le d , a r e t r e a t
i s b e in g m a d e in to th e s im p l e r f o r m s of lo c a tio n id e n tif ie r .
T h e p r o g r e s s io n
of g r id s iz e s in r e l a ti o n to d a ta e le m e n t s iz e i n c r e a s e s (SYMAP - ty p e , to
M IN N -type, to L U N R -type) a s v o lu m e of d a ta i n c r e a s e s . P o in t d a ta s y s te m s
s u c h a s GRDSR, F R IS , a n d WW W, u tiliz in g lo c a tio n id e n tif i e r s th a t p ro v id e
o n ly th e r e l a ti v e lo c a tio n o f t h e i r d a ta s e t s , a r e u s e d a s d a ta v o lu m e
in c r e a s e s .1 W ith th e tr a d iti o n a l te c h n iq u e s f o r h a n d lin g to t a l s e t s o f c e n s u s
d a ta it h a s b e e n fo u n d e s s e n ti a l to li m i t th e lo c a tio n id e n tif i e r s to n o m in a l
c o d e s.
B ey o n d th e w e ll - e s ta b li s h e d s y s t e m s is a b a n d o f o th e r s th a t a r e g e n e ra lly
o p e r a tio n a l, b u t s t i l l s o m e w h a t e x p e rim e n ta l.
T h e A U TO M A P s y s t e m c o m e s
in to th i s c a te g o ry b y r e a s o n of i t s a tte m p t to h a n d le s im p le im a g e s w ith a
r e l a ti v e ly h ig h o r d e r of lo c a tio n id e n tif ie r .
T h e D IM E, O EM , N O RD PLA N ,
a n d SACS ty p e of n e tw o rk s y s t e m s f a l l in to th i s c a te g o r y b e c a u s e , a lth o u g h
th e y u tiliz e a lo w e r o r d e r of lo c a tio n id e n tif ie r , th e y a tte m p t to h a n d le
m e d iu m v o lu m e s of d a ta .
T h e c o a rs e - p o ly g o n s y s t e m s of th e M A P /M O D E L ,
P IO S , a n d GIMMS ty p e f a l l in to th i s c a te g o r y b e c a u s e th e y co m b in e th e f i r s t
a tte m p ts a t u s in g p o ly g o n lo c a tio n id e n tif i e r s w ith s m a l l a m o u n ts o f r e l a te d
d a ta .
T h e C a n a d ia n H y d ro g ra p h ic S y s te m a n d CGIS r e p r e s e n t s y s t e m s u n d e r
d e v e lo p m e n t, w h ic h a tte m p t to h a n d le d a ta w ith a h ig h d e g r e e o f lo c a tio n
s p e c if ic ity .
I t sh o u ld b e n o te d th a t th i s is th e r e a s o n w hy th e y a r e r e l a ti v e ly
h ig h - o r d e r s y s t e m s .
p re s e n t.
N e ith e r h a n d le s l a r g e v o lu m e s of r e l a te d d a ta at
T h e C a n a d ia n H y d ro g ra p h ic S y s te m is p r i m a r i l y a n im a g e
r e p r o d u c tio n s y s te m .
CGIS s t i l l h a n d le s r e l a ti v e ly s m a l l v o lu m e s o f d a ta
a t an y o n e lo c a tio n , a lth o u g h it m a y h a n d le c o n s id e r a b ly m o r e a s i t s d e v e lo p m e n t c o n tin u e s .
T h e n e x t d ia g r a m (F ig . 6. 9) sh o w s th e r e l a tio n s h ip b e tw e e n th e m a n ip u la tio n
f a c i li tie s o f th e v a r io u s s y s t e m s a n d th e ty p e of lo c a tio n id e n tif i e r s u s e d .
1. A lthough GRDSR an d F R IS a r e d e s ig n e d to r e p r e s e n t a r e a l d a ta b y a p o in t
d a ta s u r r o g a te , it co u ld b e s u g g e s te d th a t p o in t d a ta c o lle c te d a t w e a th e r
s ta t io n s , a s in WWW, a r e p r e c i s e l y lo c a te d in a p o in t d a ta s y s te m . T h is
s u g g e s tio n w ould, h o w e v e r, b e m is le a d in g , a s th e w e a th e r s ta tio n d a ta a r e
b y d e fin itio n ta k e n a s a s a m p le o f th e a r e a l a tm o s p h e r ic c o n d itio n s an d
in d e e d a r e th e b a s i s of s u b s e q u e n t a r e a l a n a ly s is . T h e c o n s tr a in t im p o se d
b y th e d a ta - g a th e r in g p r o c e s s d o e s n o t a l t e r th e f a c t th a t a r e a l d a ta a r e
b e in g s u r r o g a te d b y p o in t d a ta f o r th e n e c e s s a r y p u rp o s e of d a ta r e d u c tio n .
Location
id e ntifie rs
213
Ma n ipu la tio n
F ig . 6. 9.
fa c ilitie s
S y s te m m a n ip u la tio n f a c i li tie s r e l a te d to lo c a tio n id e n tif ie r s .
If one c o n s id e r s th e h u m a n m in d to b e th e e q u iv a le n t of a m o n ito r s y s t e m
an d q u e r y la n g u a g e c o m b in e d (and f r o m th e c o n c lu s io n s r e a c h e d in C h a p te r
3, it p e r f o r m s th e s e fu n c tio n s w ith c o n s id e ra b le e ffic ie n c y ), th e n ,
d is r e g a rd i n g v o lu m e of d a ta , m a n u a l p r o c e s s e s m a y b e s a id to b e a p p lic a b le
t o a n y ty p e of m a n ip u la tiv e a c tiv ity , in c o n c e r t w ith an y ty p e of lo c a tio n
i d e n tif i e r e n c o m p a s s e d in th e a b o v e d ia g ra m .
B e c a u s e of th e li m ita tio n s o f h u m a n m o to r c a p a c ity an d h u m a n ch a n n e l
c a p a c ity , h o w e v e r, o n ly th e s im p le s t of m a n ip u la tiv e fu n c tio n s c a n b e
214
h a n d le d e c o n o m ic a lly b y m a n u a l p r o c e s s e s .
F o r ev e n lim ite d v o lu m e s of
d a ta , th e e v id e n c e p r e s e n t e d in C h a p te r 3 in d ic a te s th a t m a n u a l te c h n iq u e s
c a n o n ly b e c o n s id e r e d e c o n o m ic a l in a p p r o x im a te ly th e f i r s t tw o le v e ls o f
m a n ip u la tio n f a c i li ty id e n tif ie d in th e d ia g ra m . (T h is, h o w e v e r, h a s n o t
p r o h ib ite d t h e i r a p p lic a tio n to v e r y s m a l l v o lu m e s of d a ta f o r h ig h e r - o r d e r
m a n ip u la tio n p r o c e d u r e s .)
T h e d e v e lo p m e n t of c o m p u te r - a id e d s y s t e m s h a s
th u s s e e n i t s g r e a t e s t p r o li f e r a ti o n in le v e ls 3, 4, a n d 5 of m a n ip u la tio n
p r o c e d u r e , a s m a y b e e x p e c te d .
T h e s e e s s e n ti a ll y r e p r e s e n t th e im m e d ia te
e x te n s io n of m a n u a l p r o c e s s in g c a p a b ility .
F r o m th e d is tr ib u tio n of th e
s y s t e m s o n th e d ia g r a m , i t c a n b e s e e n th a t tr a d iti o n a l c e n s u s h a n d lin g
te c h n iq u e s , a n d th e l a r g e r g r id s y s t e m s LUNR a n d MINN, o v e r la p in to th e
a r e a of e c o n o m ic a l m a n u a l te c h n iq u e s .
T h e y c o m p e te d ir e c tl y w ith
p r o c e s s e s th a t a r e s t i l l m a n u a lly e f fic ie n t (a s s u m in g lim ite d d a ta s e ts ) .
A U TO M A P c a n c a r r y o u t s e a r c h , s c a l e c h a n g e , a n d p r o je c tio n ch a n g e on
e x p lic itly d e fin e d b o u n d a r ie s , b u t th e s e a c tiv i tie s a p p e a r to b e a t th e li m it s
of m a n u a l e ffic ie n c y e v e n th o u g h th e y a r e c a r r i e d o u t m a n u a lly w ith s o m e
r e g u l a r ity .
A n id e n tifia b le g ro u p o f s y s t e m s f a l l s w e ll w ith in le v e ls 3, 4, a n d 5 of
m a n ip u la tio n f a c ility .
T h e s e p r o c e s s e s a r e d e m o n s tra b ly e x p e n siv e to
c a r r y o u t m a n u a lly , a n d i t i s to b e e x p e c te d th a t c o m p u te r - a id e d te c h n iq u e s
w o u ld b e f i r s t d e v e lo p e d f o r s u c h f a c i li tie s .
f a ll in to th i s li m it e d a r e a .
T e n of th e 19 s y s t e m s show n
I t i s in t e r e s ti n g t o n o te , h o w e v e r, th a t th e r a n g e
o f lo c a tio n id e n tif i e r s e m p lo y e d b y s u c h s y s te m s i s s t i l l q u ite lim ite d .
They
u s e p o in t d a ta s e t s , s m a l l g r id s , o r s im p le n e tw o rk r e p r e s e n t a ti o n s a s t h e i r
b a s ic d a ta f o r m a ts .
L ittle c a p a b ility e x i s t s to p e r f o r m th e h ig h e r m a n ip u la ­
tio n fu n c tio n s of th e f i r s t c a te g o r y on th e m o re e x p lic itly d e fin e d s p a tia l d a ta .
S y s te m s in c o r p o r a tin g a n o v e r la y c a p a b ility n e c e s s a r i l y o c c u r in th e u p p e r
h a lf of th e lo c a tio n id e n tif i e r a x is b e c a u s e , u n le s s b o u n d a rie s a r e e x p lic itly
id e n tifie d , th e u n io n of d a ta s e t s c a n b e a c c o m p lis h e d b y s u m m a r y .
The
r e l a ti v e ly s m a ll n u m b e r o f s y s t e m s in c o r p o r a tin g th is c a p a b ility (fiv e o ut
o f 19) s u g g e s ts th a t e i th e r l i t t l e r e q u i r e m e n t e x i s t s f o r th e r e s u l t s o f o v e r la y ,
o r th e p r o c e s s r e q u i r e s te c h n iq u e s th a t a r e m a in ly e x p e rim e n ta l a t p r e s e n t.
T h e t r u t h p ro b a b ly l i e s in a c o m b in a tio n of th e s e f a c t o r s , alth o u g h th e
215
te c h n ic a l d if fic u ltie s m a y p r e s e n t th e g r e a t e r c o n s tr a in t.
T h e c o a r s e p o ly -
gon ty p e of s y s t e m (M A P /M O D E L , P IO S , GIMMS) f o r m s a n id e n tifia b le
g ro u p a t th e lo w e r en d of th e h ie r a r c h y of s y s te m s u s in g e x p lic it b o u n d a rie s .
O nly th e C a n a d ia n H y d ro g ra p h ic S y s te m a n d CGIS a tte m p t o v e r la y m a n ip u la tio n s on f in e ly d e fin e d p o ly g o n s; th e l a t t e r s y s t e m a ls o in c o r p o r a te s a
f u ll m o n ito r s y s t e m an d q u e r y la n g u a g e c a p a b ility .
T h e n e x t d ia g r a m (F ig . 6. 10) i l l u s t r a t e s th e m a n ip u la tio n f a c i l i t i e s o f th e
Manipulation
fa c ilitie s
v a r io u s s y s t e m s in r e l a ti o n to th e v o lu m e of d a ta a t e a c h lo c a tio n .
V o lu m e
F ig . 6. 10.
of
r e l a t e d da ta
S y s te m m a n ip u la tio n f a c i l i t i e s r e l a te d t o v o lu m e o f d a ta
p e r lo c a tio n .
A s w a s n o te d in C h a p te r 3, a n i n c r e a s e in th e v o lu m e of d a ta r a p id ly d e c r e a s e s
th e u tility of m a n u a l p r o c e s s e s .
T h e d ia g r a m il l u s t r a t e s th e e ffe c t of
216
in c r e a s in g v o lu m e s of r e l a t e d d a ta on e v e n th e s im p l e s t m a n u a l m a n ip u la tio n p r o c e s s e s .
In F ig . 6. 8 ( s y s te m s in th e r e c o r d p la n e ), it w a s s u g g e s te d
th a t tr a d iti o n a l c o m p u te r-a id e d c e n s u s te c h n iq u e s , a n d th e l a r g e r g r id - b a s e d
s y s t e m s (LU N R a n d MINN), w e r e n o t e c o n o m ic a l to p e r f o r m m a n u ally .
In F ig . 6. 9 (m a n ip u la tio n f a c i li tie s r e l a t e d to lo c a tio n id e n tif ie r s ) , th e y
a p p e a r e d to b e c o m p e tin g w ith m a n u a l p r o c e s s e s , a s s u m in g lim ite d am o u n ts
of d a ta .
F ig . 6. 10 sh o w s th a t th e u tility o f t h e s e s im p le a p p r o a c h e s
to s p a ti a l d a ta m a n ip u la tio n r e s t s on t h e i r e c o n o m y in h a n d lin g m e d iu m to
l a r g e a m o u n ts o f d a ta r a t h e r th a n on t h e i r r e s o lu t io n o f lo c a tio n id e n tif ie r .
T o w a rd th e le f t o f th e d ia g r a m , in th e f i r s t c a te g o r y of v o lu m e o f r e l a te d
d a ta , th e im a g e r e p r o d u c tio n s y s t e m s c a n b e id e n tifie d .
A UTOM A P a p p e a r s
to b e a l o w - o r d e r s y s t e m in th e s e t e r m s , a lth o u g h it h a n d le s a h ig h - o r d e r
s e t of e x p lic it lo c a tio n id e n tif ie r s .
T h e h ig h e s t o r d e r of th e im a g e m a n ip u la -
tio n s y s t e m s sh o w n i s u n d o u b te d ly th e C a n a d ia n H y d ro g ra p h ic S y ste m , c o m b in in g a s i t d o e s a h ig h c a p a b ility f o r m a n ip u la tio n w ith h ig h - r e s o lu tio n
lo c a tio n id e n tif i e r s . (Its p u rp o s e is to m a n ip u la te p r e c i s e h y d ro g ra p h ic
c h a r t s p r e p a r e d f o r n a v ig a tio n a l p u r p o s e s .) T h e m id d le r a n g e of th e im a g e
re p r o d u c tio n s y s t e m s i s o c c u p ie d b y th e T y p e 2 a r b i t r a r y r e g u l a r - a r e a 1
f a m ily (SY M A P, M IADS, e t c . ) th a t a c c e p ts a low to m e d iu m le v e l of lo c a tio n
id e n tif i e r ( s m a ll g r id s ) b u t o f f e r s a r e l a ti v e ly w id e r a n g e of c a p a b ility f o r
m a n ip u la tio n in th e n o n -o v e rla y c a te g o ry .
T h e n e x t g ro u p i s F R IS , SACS, D IM E, O EM , GRDSR, N O R D PLA N , an d WWW.
T h e s e s y s t e m s a r e c h a r a c te r iz e d b y a f a i r l y e x te n s iv e c a p a b ility f o r m a n ip u la tio n in th e n o n - o v e r la y c a te g o ry , a n d b y a v a r i e d b u t m e d iu m le v e l of
lo c a tio n id e n tif i e r (s e e F ig . 6. 9); h o w e v e r, a l l in s o m e w a y a tte m p t to
h a n d le c o n s id e r a b le q u a n titie s o f d a ta r e l a t e d to t h e i r lo c a tio n id e n tif ie r s .
R e g a r d le s s of lo c a tio n id e n tif ie r , th e e m p h a s is i s on r e l a t e d d a ta h an d lin g .
It i s s ig n ific a n t th a t, w ith th e e x c e p tio n of WWW ( it s e lf a s y s t e m h a n d lin g
la r g e a m o u n ts of d a ta ), a l l s y s te m s in th i s g ro u p h a v e b e e n d ev e lo p ed in
a g e n c ie s d ir e c tl y r e l a t e d to c e n s u s an d a d m in is tr a tiv e d a ta h an d lin g a c tiv itie s .
T h i s , th e n , i s th e g ro u p th a t h a s a tte m p te d to h a n d le l a r g e q u a n titie s of
d a ta a n d h a s c o m p ro m is e d on lo c a tio n id e n tif ie r an d m a n ip u la tio n c a p a b ility
(at th e m o m e n t).
1. A s d e fin e d in C h a p te r 4, p. 98.
217
In th e o v e r la y c a te g o r y i s th e w e ll - e s ta b li s h e d g ro u p (in a l l th r e e d ia g r a m s )
o f GIM M S, P IO S , an d M AP / M OD EL.
H e r e th e e m p h a s is h a s b e e n on th e
d e v e lo p m e n t of c a p a b ility f o r m a n ip u la tio n , an d in e v e ry c a s e th e file
s t r u c t u r e is d e s ig n e d f o r th i s r a t h e r th a n f o r c a r r y i n g la r g e a m o u n ts o f d a ta .
I t is r e l e v a n t th a t e a c h s y s t e m h a s b e e n d e v e lo p e d b y p la n n e r s o r g e o g r a p h e r s
c o n c e rn e d w ith s p a ti a l a n a l y s i s , r a t h e r th a n th e m a n ip u la tio n o f la r g e d a ta
s e ts .
T h e CG IS s y s t e m h a s a s u b s t a n ti a l c a p a b ility f o r m a n ip u la tio n b u t a t p r e s e n t
i t d o e s not c a r r y l a r g e v o lu m e s o f r e l a te d d a ta a t e a c h lo c a tio n .
T h e f ile
s t r u c t u r e of th e s y s t e m (th e s e p a r a t e d e s c r i p to r d a ta f ile s ) is in p la c e to
h a n d le s u b s t a n ti a l q u a n titie s of r e l a t e d d a ta in a n e ffic ie n t m a n n e r.
In s u m m a r y , th e f i r s t d ia g r a m of th e t h r e e (F ig . 6. 8) g e n e r a lly il l u s t r a t e s
th e c u r r e n t s ta t u s of d e v e lo p m e n t of s y s te m s a n d t h e i r a b ility to h an d le
v a r i o u s ty p e s o f d a ta .
T h e tw o d ia g r a m s t h e r e a f t e r (F ig s . 6. 9 a n d 6. 10)
c l a r if y th e f i r s t an d p e r m it c e r t a in g ro u p c h a r a c t e r i s t i c s to b e c o m e
a p p a re n t.
T h e im a g e -h a n d lin g s y s t e m s , w ith t h e i r v a ry in g le v e ls of
lo c a tio n id e n tif i e r a n d c a p a b ility f o r m a n ip u la tio n , ca n b e re c o g n iz e d .
T h is
g ro u p i s p r o b a b ly r e p r e s e n t a ti v e of s y s te m s of " a u to m a tic c a rto g r a p h y " now
in e m b r y o n ic s ta g e s of d e v e lo p m e n t in v a r io u s tr a d iti o n a l c a r to g r a p h ic
in s titu tio n s .
T h e g ro u p u tiliz in g lo w - le v e l lo c a tio n id e n tif ie r s (CENSUS,
LU N R , MINN) c a n b e id e n tifie d a s d ep e n d in g on d a ta v o lu m e f o r t h e ir
e c o n o m ic a p p lic a tio n .
T h e l a r g e r g ro u p of w o rk in g s y s t e m s , w ith n o n -
o v e r la y m a n ip u la tio n f a c i li ty an d s o m e v a r i e ty of m e d iu m - le v e l lo c a tio n
i d e n tif i e r , a r e show n to b e th o s e a tte m p tin g to ta c k le th e p r o b le m o f h a n d lin g
d a ta v o lu m e w ith g r e a t e r f a c i li ty th a n is o f fe re d e i th e r b y m a n u a l te c h n iq u e s
o r b y th e s y s t e m s u s in g lo w - le v e l lo c a tio n id e n tif i e r s .
T h e y d ir e c tl y r e f l e c t
th e im m e d ia te n e e d s of th e a g e n c ie s d ev e lo p in g them ..
T h e c o a rs e - p o ly g o n g ro u p of s y s t e m s (M A P /M O D E L , P IO S , GIMMS, e t c .)
c a n b e id e n tifie d , a n d e s s e n ti a ll y r e p r e s e n t s an a tte m p t to a c h ie v e th e
c a p a b ility f o r s p a ti a l m a n ip u la tio n on lim ite d d a ta s e ts an d to f a c i li ta te th e
g r a p h ic t a s k s th a t a r e p r o h ib itiv e ly e x p e n siv e b y m a n u a l m e th o d s.
CG IS i s a r e s e a r c h s y s t e m d e s ig n e d to h a v e a r e l a ti v e ly h ig h c a p a b ility f o r
m a n ip u la tio n c o u p le d w ith th e p o te n tia l to h a n d le m e d iu m to la r g e d a ta s e t s .
218
I t m u s t b e e m p h a s iz e d th a t th e d ia g r a m s th e m s e lv e s a r e n o t, an d ca n n o t b e
c o n s id e r e d , a p r e c i s e to o l f o r r e l a ti n g s y s t e m c a p a b ilitie s ; th e y m e r e ly
p ro v id e a c o n c e p tu a l f r a m e w o r k f o r d is c u s s io n an d f o r th e s e g e n e r a l
o b s e rv a tio n s .
C o n s id e rin g th e t h r e e v a r i a b le s a s th e a x e s of a cu b e , a s il l u s t r a t e d in
F ig . 6. 11, th e d ia g o n a l OS e s s e n ti a ll y r e p r e s e n t s th e p o te n tia l c a p a c ity
o f a f il e s t r u c t u r e to h a n d le in fo rm a tio n in a n y lo c a tio n - s p e c if ic in fo r m a tio n
s y s te m .
L o c at i o n
identifier
s
o
F ig . 6. 11.
D iag o n a l OS a s a v e c to r o f p o te n tia l c a p a b ility o f s y s t e m
f il e s t r u c t u r e s .
If th e d ia g o n a l a x is is d iv id e d a r b i t r a r i l y b e tw e e n O a n d S in to t e n e q u a l
p a r t s , r e f e r e n c e to th e t h r e e p r e v io u s d ia g r a m s ( F ig s . 6. 8, 6. 9, a n d 6. 10)
sh o w s th a t th e p o r tio n of th e cube p a s s e d th ro u g h b y th e lo w e s t t h r e e u n its
e n c o m p a s s e s v a r i a b le s th a t to g e th e r m a y c o m p ris e th e f ie ld w h e r e c u r r e n t
m a n u a l m e th o d s of s to r in g a n d m a n ip u la tin g d a ta a r e e c o n o m ic an d
s a ti s f a c to r y to th e u s e r .
T h e p o r tio n of th e c u b e b e tw e e n le v e ls 3 an d 4 on th e d ia g o n a l c o n ta in s th e
p r o li f e r a ti o n o f c u r r e n t w o rk in g s y s te m s a c c o r d in g to t h e i r n e e d to h a n d le
im a g e s o r r e l a te d d a ta s e ts .
T h e s e p ro b a b ly in d ic a te th e le v e l o f f ile
s t r u c t u r e a n d d e s ig n , co u p led w ith m a c h in e c a p a b ility , th a t h a s c u r r e n t ly
219
found e c o n o m ic a c c e p ta n c e .
F u r t h e r s y s t e m s , if d e v e lo p e d w ith c o m b in a tio n s
of v a r i a b le s th a t f a l l in to th i s c a te g o r y , sh o u ld b e im p le m e n te d w ith o u t
d iffic u lty a n d b e e ffic ie n t t o u s e .
A s o n e p r o c e e d s up th e d ia g o n a l, th e f ile s t r u c t u r e s n e c e s s a r i l y b e c o m e m o r e
s o p h is tic a te d ; in f a c t , a s th e o rth o g o n a l a x e s th e m s e lv e s e x h ib it lo g a r ith m ic
p r o g r e s s io n , th e d ia g o n a l a x is is p r o b a b ly lo g a r ith m ic .
T h e ty p e a n d c a p a -
c ity o f th e d a ta p r o c e s s in g m a c h in e r e q u i r e d , a s w e ll a s th e d e g r e e of s k ill
n e e d e d to u s e it e ffic ie n tly , s i m i l a r l y p r o g r e s s .
T y p ic a l o f th e s y s t e m s a t
le v e ls 5 t o 7 a r e th e im a g e -h a n d lin g s y s te m s of A U T O M A P, th e C a n a d ia n
H y d ro g ra p h ic S y ste m , a n d a l s o th e PIO S, M AP / M O D EL, GIMMS g ro u p .
I t sh o u ld b e n o te d th a t th e d ia g o n a l r e p r e s e n t s th e p o te n tia l c a p a b ility o f th e
s t r u c t u r e s a t th e s e le v e ls .
a t i t s f u ll p o te n tia l.
In s o m e in s ta n c e s th e f il e s t r u c t u r e i s n o t u s e d
T h e b a s i c c h a r a c t e r i s t i c s m a y b e e m p lo y e d , b u t th e
s u b s t r u c tu r e s w ith in th e g e n e ra l f ile o rg a n iz a tio n h a v e n o t b e e n d ev e lo p ed .
T h e s t r u c t u r e co u ld b e s a id to b e lik e a s k e le to n th a t i s c a p a b le o f s u p p o rtin g
a b o d y b u t d o e s n o t h a v e th e f le s h a n d a n c illa r y s y s t e m s in p la c e , o r d o es
n o t n e e d th e m a t th e m o m e n t.
P e r h a p s o n e le v e l h ig h e r i s th e ty p e of s y s t e m r e p r e s e n t e d b y C G IS, b e c a u s e
s u c h s y s t e m s a tte m p t to c a r r y m o re r e l a te d d a ta th a n do th o s e m a in ly
c o n c e r n e d w ith th e m a n ip u la tio n of im a g e s .
A t th i s le v e l, e f f ic ie n c y of o p e r a -
t io n is c lo s e ly r e l a t e d to f il e s t r u c t u r e a n d th e o p tim u m u s e o f co m p u tin g
fa c ilitie s .
H e re a g a in , h o w e v e r, th e p o te n tia l c a p a b ility o f th e f il e s t r u c t u r e
i s c u r r e n t ly u n d e r-u tiliz e d . W ith in th e g e n e ra l f r a m e w o r k o f th e e x is tin g
CGIS f il e s t r u c t u r e , a w id e v a r i e ty of s u b s t r u c tu r e s c o u ld b e d e v e lo p e d in
r e s p o n s e to u s e r d e m a n d s , b u t th e y h a v e n o t y e t b e e n e s ta b lis h e d .
R e m e m b e rin g th a t th e d ia g o n a l p ro b a b ly p r o g r e s s e s lo g a r ith m ic a lly in t e r m s
of in c r e a s in g c o m p le x ity , i t c a n b e n o te d th a t no file s t r u c t u r e s h a v e b e e n
d e v e lo p e d in th e h ig h e r p a r t s of th e ra n g e .
Such s y s t e m s d e m a n d s o p h is -
tic a t e d d e s ig n , a n d p ro b a b ly th e u s e of c o m p u te r f a c i li tie s n o t c u r r e n t ly
a v a ila b le .
T h e a r e a , h o w e v e r , e n c o m p a s s e s s y s t e m s th a t m u s t m a n ip u la te
l a r g e v o lu m e s of d a ta w ith h ig h - r e s o lu tio n lo c a tio n id e n tif i e r s .
T h e d a ta
s e t s to b e h a n d le d in th i s m a n n e r a r e n o t y e t in m a c h in e - r e a d a b le f o r m .
A ls o , th e im p le m e n ta tio n of s u c h c a p a b ility m u s t aw a it th e d e v e lo p m e n t of
220
c o n s id e r a b ly im p ro v e d p r o c e s s e s of g r a p h ic to n o n -g r a p h ic d a ta c o n v e rs io n ,
o r th e d e v e lo p m e n t of a d v a n c e d co m p u tin g c a p a b ility , o r b o th .
E ven m o re
fu n d a m e n ta lly , it a w a its th e n e e d of u s e r s to h a n d le s u c h d a ta s e ts .
A lth o u g h th i s a p p ro a c h to g e o g r a p h ic a l in fo rm a tio n s y s t e m s c r e a t e s s o m e
u n d e r s ta n d in g of th e r e la tio n s h ip b e tw e e n c h a r a c t e r i s t i c s of th e v a r io u s
s y s t e m s , i t s p r im a r y p u r p o s e i s n o t to e s ta b lis h a h ie r a r c h y of s y s t e m
s o p h is tic a tio n .
R a th e r , it a llo w s th e s y s te m s to b e e x a m in e d in t e r m s of
a v a ila b le e n v iro n m e n ta l d a ta and th e e f f o r t r e q u i r e d to h a n d le th e m .
Ju st
a s th e v a r i a b le s of lo c a tio n id e n tif i e r , v o lu m e of r e l a t e d d a ta , a n d m a n ip u la tio n f a c i li ty m a y b e u s e d to d e s c r ib e th e s y s t e m s , s o m a y th e y s e r v e
to in d ic a te th e r e q u i r e m e n t s f o r h a n d lin g d a ta to p r o v id e a b e t t e r d e s c r ip tio n
a n d u n d e r s ta n d in g of th e e n v iro n m e n t.
B y e x te n s io n , th e s a m e ty p e of cu b e o r m a tr ix u s e d a s a f r a m e w o r k f o r
s y s t e m d e s c r i p tio n co u ld b e u s e d to e x a m in e th e d a ta h a n d lin g r e q u ir e m e n ts
of th e u s e r , a n d th e r e la tio n s h ip s b e tw e e n s y s t e m c a p a b ility an d e n v ir o n m e n ta l d a ta h a n d lin g n e e d s .
F u r th e r , it m a y b e p o s s ib le to r e l a t e th e
c a p a b ilitie s of g e o g ra p h ic a l in fo r m a tio n s y s t e m s to th e c a p a b ilitie s of d a ta
g a th e r in g p r o c e s s e s .
In s i m i l a r t e r m s th e s ta t e d r e q u i r e m e n t s of th e u s e r
m a y b e r e l a t e d to th e v a r io u s ty p e s of d a ta a n a ly s is , an d to th e d e c is io n s
th a t d ep e n d on s u c h a n a ly s e s .
T h e s e lin k a g e s , a n d h e n c e th e o v e r a l l u tility
of s p a ti a l d a ta h a n d lin g s y s t e m s , w ill b e e x a m in e d in th e fo llo w in g c h a p te r .
221
C H A P T E R 7 - G EO GRA PHIC IN FO RM A TIO N SYSTEM S, S PA T IA L DATA
ANALYSIS, AND D ECISION MAKING IN G OVERNM ENT
In g e n e r a l, th e fiv e p r e v io u s c h a p te r s o f th i s th e s i s h a v e h a d a te c h n ic a l
e m p h a s is .
R e la tiv e ly l i ttl e d is c u s s io n h a s b e e n p ro v id e d ab o u t th e th e o r y
o n w h ich s p a ti a l d a ta a n a ly s is is im p lic itly o r e x p lic itly b a s e d , ab o u t th e
i n s ti tu ti o n s th a t h av e f o s te r e d th e d e v e lo p m e n t of v a rio u s d a ta h a n d lin g
s y s t e m s , o r ab o u t th e g e n e ra l s o c io -e c o n o m ic c o n te x t in w h ich g e o g ra p h ic
in f o rm a tio n s y s t e m s h a v e ev o lv ed .
P r o c e s s e s o f d a ta g a th e r in g , c h a r a c t e r i s t i c s of d a ta , a n d te c h n iq u e s of
m a n ip u la tio n a r e in e x tr ic a b ly lin k e d w ith m e th o d s of d a ta a n a ly s is , i n s t i tu tio n a l s t r u c t u r e s an d a c tiv i tie s , a n d th e n e e d to m a k e d e c is io n s ab o u t
r e a l - w o r l d p r o b le m s , e v e n if t h e i r in te rd e p e n d e n c e is not c l e a r o r c o m p le te ly
u n d e rs to o d .
T h is c h a p te r w ill b r ie f ly e x a m in e s o m e a s p e c t s of th e s e
in t e r r e la tio n s h ip s in o r d e r to il l u s t r a t e th e o v e r a l l v a lu e o f g e o g ra p h ic
in fo r m a tio n s y s te m s a s th e y a r e know n to d a y , an d to show th a t th e y h av e
g ro w n o u t of a c o m b in a tio n of p r a g m a tic n e e d a n d in t e ll e c tu a l c u r i o s i ty a s
m u c h a s f r o m an y n a r r o w ly d efin ed p r o g r e s s io n of te c h n ic a l e v o lu tio n .
T h e c o n c e p tu a l e x te n t of th e s u b je c t, h o w e v e r, i s e n o r m o u s .
It w ou ld , f o r
e x a m p le , b e q u ite p r o p e r to c o n s id e r th e l a r g e - s c a l e s o c ia l an d p o litic a l
b a c k g ro u n d 1 of in s titu tio n s , in o r d e r to u n d e rs ta n d t h e i r p r i o r i t i e s and
a c tio n s in in fo rm a tio n p r o c e s s in g .
I t w o u ld b e v a lid to t r a c e th e im p a c t o f
d a ta on d e c is io n s in th e v a rio u s in s titu tio n s w ith in d iffe re n t s o c ia l an d
p o li tic a l s t r u c t u r e s .
It w o u ld a l s o b e v a lu a b le to a s s e s s th e v a lid ity o f th e
t h e o r i e s c o n s c io u s ly o r s u b c o n s c io u s ly a p p lie d in th e c u r r e n t g a th e r in g of
d a ta (th e th e o r ie s u n d e rly in g th e m e a s u r e m e n t, s a m p lin g , c la s s if ic a tio n ,
a n d r e c o r d i n g o f d a ta ).2
T h e s e a r e im p o r ta n t an d n e c e s s a r y to p ic s f o r s tu d y
a n d m u s t b e e x a m in e d if th e v a lu e of in fo rm a tio n s y s t e m s is to b e f u lly u n d e r sto o d .
A ny d is c u s s io n of th e s e b r o a d e r i s s u e s in th e co n c lu d in g c h a p te r s of
th e t h e s i s , h o w e v e r, w o u ld n e c e s s a r i ly b e s u p e r f ic ia l an d u n s a tis f a c to r y .
T h e th e s i s h a s b e e n c o n c e rn e d w ith th e h a n d lin g of s p a ti a l d a ta g a th e r e d b y
g o v e rn m e n t a g e n c ie s ; th e r e f o r e , th e d is c u s s io n in th i s c h a p te r w ill fo c u s on
1. S ee, f o r e x a m p le , T o m lin s o n , R . F . 1971. 2. S ee, f o r e x a m p le , C o o m b s
1964, an d th e d is c u s s io n in H a rv e y 1969, C h a p te r 17.
222
th e c o n tr ib u tio n of s y s t e m s f o r h an d lin g s p a ti a l d a ta to th e a n a ly s is o f
s p a ti a l d a ta a n d d e c is io n m a k in g in g o v e rn m e n t.
T h e c o n c e p t of th e r e la tio n s h ip s b e tw e e n th e th r e e e le m e n ts i s e x p r e s s e d
in s im p l e s t t e r m s in F ig . 7. 1.
G o v e rn m e n ta l
d e c is io n m a k in g
F o rm a l
s p a ti a l
a n a ly s is
F ig . 7. 1.
G eo g rap h ic
in fo rm a tio n
s y s te m s
R e la tio n s h ip s b e tw e e n d a ta , a n a ly s is , an d d e c is io n .
T h e c i r c u l a r n a t u r e of th e d ia g r a m im m e d ia te ly e m p h a s iz e s th e d iffic u lty of
b r e a k in g in to th e p r o b le m a t an y one p o in t.
T h e a v a ila b ility of d a ta c o n -
s t r a i n s a n a ly s is , y e t a n a ly s is ( o r th e th e o r y b e h in d it) sh o u ld b e a g u id e to
w h a t d a ta a r e m a d e a v a ila b le .
In t e r m s o f d e c is io n m a k in g , th e a n a ly s is
r e q u i r e d d e p e n d s o n th e d e c is io n s th a t m u s t b e m a d e , an d th e d e c is io n s in
t u r n c a n b e a ffe c te d b y th e a n a ly tic a l c a p a b ility .
D e c isio n s ca n b e m a d e
d i r e c t l y f r o m d a ta (a s s u m in g th e e x is te n c e o f s o m e m e n ta l m o d e l), a n d 'th e
c o n c e r n s of th e co m m u n ity a n d th e n a t u r e of i t s in s titu tio n s ca n in flu e n c e
th e d a ta a c tu a lly g a th e re d .
T h e t r a n s l a ti o n of th i s s im p le c o n c e p tu a l
d ia g r a m in to a m o d e l r e l a ti n g te c h n iq u e s of d a ta h a n d lin g to s p a tia l th e o r y
a n d th e p r a c t i c e of in s titu tio n a l d e c is io n m a k in g is n o t s tr a ig h tf o r w a r d .
T h e r e a r e d iffic u ltie s in u s in g a r ig o r o u s la n g u a g e to a b s tr a c t th e r e l a t i o n s h ip s , in s ta t in g r e a s o n a b le c o n c e p ts th a t a r e p r e c i s e an d u n a m b ig u o u s, an d
in d e v e lo p in g p r e c i s e s ta te m e n ts o f th e r e la tio n s h ip s th a t b in d th e c o n c e p ts
to g e th e r .
T h e d ia g r a m c a n th u s b e u s e d o n ly a s a f r a m e w o r k f o r d is c u s s io n
in a p r e l im i n a r y e x a m in a tio n of th e r e la tio n s h ip s involved .
T h e c h a r a c t e r i s t i c s of g e o g ra p h ic in fo r m a tio n s y s te m s an d th e c a p a b ility o f
t h e i r te c h n iq u e s to h a n d le s p a ti a l d a ta h a v e b e e n e x a m in e d in th e p re v io u s
c h a p te r s .
T h e r e m a in d e r of th i s c h a p te r w ill c o n s id e r th e c h a r a c t e r i s t i c s ,
223
f i r s t , of f o r m a l s p a ti a l a n a ly s is , an d th e n o f g o v e rn m e n ta l d e c is io n m a k in g ,
in t e r m s of t h e i r n e e d s to h a n d le s p a ti a l d a ta .
T h e v a rio u s c a te g o r ie s o f
e x is tin g g e o g ra p h ic in fo rm a tio n s y s t e m s id e n tifie d in C h a p te r 6 w ill be
e x a m in e d in th i s c o n te x t, th e in s titu tio n a l b a s is of t h e i r d e v e lo p m e n t w ill
b e d is c u s s e d , an d th e u s e f u ln e s s of th e d iffe re n t ty p e s of s y s te m w ill
b e c o m e a p p a re n t.
C h a p te r 8 w ill c o n s id e r th e f u tu r e d e v e lo p m e n ts of g e o g ra p h ic in f o rm a tio n
s y s t e m s an d e x a m in e t h e ir co n tin u in g r o l e w ith in th e d is c ip lin e o f g e o g ra p h y
a n d d e c is io n m a k in g in g o v e rn m e n t.
F O R M A L S P A T IA L ANALYSIS R E L A T E D T O DATA USE
F o r m a l s p a ti a l a n a ly s is , th e r ig o r o u s e x p la n a tio n of th e d is tr ib u tio n an d
i n t e r a c t io n of th e a t tr ib u t e s of p la c e s o n th e e a r t h 's s u r f a c e , i s c e n tr a l to
g e o g ra p h ic a l m e th o d o lo g y .
T h e c o n tr ib u tio n of th e to o ls o f g e o g ra p h ic
in fo rm a tio n s y s t e m s to f o r m a l s p a ti a l a n a ly s is i s th u s , to s o m e e x te n t, a
c o n trib u tio n m a d e to g e o g ra p h ic a l m e th o d o lo g y .
A fte r e a r l i e r d e v e lo p m e n t in s e v e r a l of th e p h y s ic a l an d b io lo g ic a l s c ie n c e s ,
th e to o l s a v a ila b le f o r r ig o r o u s e x p la n a tio n in th e s o c ia l s c ie n c e s h av e
r a p i d ly d e v e lo p e d in r e c e n t y e a r s .
In a n e s s a y on th e in te r a c tio n o f to o ls
a n d p r o b le m s in e c o n o m ic s , K o o p m a n s 1 n o te d th a t "T h e p r e s e n t p h a s e of
e c o n o m ic s i s in d e e d one of tu r b u le n c e a n d tr a n s i tio n in th e d o m a in o f to o ls ,
m o r e s o th a n in th e d o m a in of p ro b le m s a n d s u g g e s te d s o lu tio n s .
P e rh a p s
th e m o s t c o n s p ic u o u s d e v e lo p m e n t is th e in c r e a s in g u s e of a g ro w in g n u m b e r
o f m a th e m a tic a l c o n c e p ts , th e o r i e s , a n d th e o r e m s in ec o n o m ic re a s o n in g .
B u t s e v e r a l o th e r im p o rta n t d e v e lo p m e n ts d e m a n d a tte n tio n .
T h e r e i s th e
re v o lu tio n a ry in c r e a s e in th e c a p a b ilitie s of c o m p u tin g an d d a ta - p r o c e s s in g
e q u ip m e n t; th e in c r e a s e d a p p lic a tio n o f m e th o d s of s t a t i s t i c a l in f e r e n c e ,
in c lu d in g m e th o d s s p e c if ic a lly d e s ig n e d f o r e c o n o m ic p ro b le m s ; th e o p p o r tu n i tie s a f fo rd e d b y s y s te m a tic a p p lic a tio n of s a m p le s u r v e y m e th o d s of
o b s e r v a tio n . "
T h e w o rd s of K o opm ans in 1957 w ill s e e m f a m ili a r to th e e a r s o f g e o g r a p h e r s ,
w ho h a v e w itn e s s e d a s i m i l a r r a d i c a l tr a n s f o r m a tio n in th e s p i r i t an d p u rp o s e
o f g e o g r a p h ic a l m eth o d o lo g y in th e p a s t 15 y e a r s .
1. K o o p m an s 1957.
T h e y s e r v e , h o w e v e r, to
224
p la c e th e c o n trib u tio n o f c o m p u te r-a id e d s y s t e m s of d a ta h an d lin g in
co n te x t w ith th a t of th e o th e r r e c e n tly a r r i v e d " to o ls " .
P e r h a p s a c l e a r e r d is tin c tio n sh o u ld b e m a d e a t th is p o in t b etw e en th e
e m e r g e n c e o f th e c a p a b ilitie s of c o m p u te r s to p e r f o r m c a lc u la tio n s an d t h e ir
u s e f o r g e o g ra p h ic in fo r m a tio n s y s t e m s .
A t th e b e g in n in g o f C h a p te r 4 it
w a s n o te d th a t b e f o r e 1960, c o m p u te rs w e r e e s s e n ti a ll y h ig h - s p e e d
c a lc u la tin g m a c h in e s , a n d n o t u n til th e e a r l y m id -1 9 6 0 s d id d e v e lo p m e n ts
in c o m p u te r te c h n o lo g y allow r a p i d g ro w th in t h e i r u s e f o r in fo rm a tio n
h a n d lin g an d th e n o n -g ra p h ic s to r a g e o f s p a ti a l d a ta .
Y et in 1963, in a co g e n t
re v ie w of th e im p a c t of th e n e w e r to o ls on g e o g ra p h ic a l m e th o d o lo g y ,
B u rto n 1 s ta t e d th a t, w h ile " th e c o n s e q u e n c e s of th e r e v o lu tio n h a v e y e t to b e
w o rk e d o u t a n d a r e lik e ly to in v o lv e th e 'm a th e m a tiz a tio n ' o f m u ch o f o u r
d is c ip lin e w ith th e a tte n d a n t e m p h a s is on th e c o n s tr u c tio n a n d te s t in g of
t h e o r e t i c a l m o d e ls , " an d " a lth o u g h th e fu tu r e c h a n g e s w ill f a r o u tru n th e
i n i tia l e x p e c ta tio n s of th e r e v o l u tio n a ri e s , th e (q u a n tita tiv e ) r e v o lu tio n is
now o v e r . " C e r ta in ly , b y 1 9 6 2 -6 3 , th e to o ls of m a th e m a tic s , th e te c h n iq u e s
o f s t a t i s t i c a l in fe re n c e an d s a m p lin g , a n d the. c a lc u la tin g c a p a c ity of c o m ­
p u te r s h a d b eg u n to m a k e a s ig n ific a n t im p a c t on g e o g ra p h ic a l m e th o d o lo g y .
H o w e v e r, a t th a t tim e n o t one of th e n u m e r o u s c o m p u te r - a id e d te c h n iq u e s
f o r h a n d lin g s p a ti a l d a ta a v a ila b le to d a y a n d d e s c r ib e d in th is th e s i s h a d b e e n
d e v e lo p e d .
C oppock2 in 1962 c l e a r l y saw th e lim ita tio n s of th e c o m p u te rs
of th e tim e a n d n o te d th a t th e " b o o k -k e e p in g " ty p e o f c o m p u te r w a s p ro b a b ly
f a s t e r f o r l a r g e - s c a l e d a ta m a n ip u la tio n th a n th e " s c ie n tif ic " c o m p u te r s th e n
a v a ila b le .
H e c o m m e n te d th a t "w ith a m a c h in e of l a r g e r s to r a g e c a p a c ity ,
it m ig h t h a v e b e e n p o s s ib le to p r in t o u t r e s u l t s . . . " s o r te d b y g e o g ra p h ic
c o o r d in a te s to m a k e m ap d ra w in g e a s i e r .
Such d e v e lo p m e n ts w e r e a n tic i-
p a te d b y T o m lin s o n ,3 K ao ,4 an d o th e r s , b u t e v e n th e s im p l e r f o r m s of
s y s t e m s w ith g r id s to r a g e f o r m a ts (s u c h a s SYM AP5 an d MIADS6) d id n ot
a p p e a r u n til 1964-66.
T o b l e r 's 7 e a r l y c o n trib u tio n to e x p e rim e n ta l a u to -
m a te d p r e p a r a tio n of th e m a tic m a p s w a s p u b lish e d in 1964.
T h e d e v e lo p m e n t
o f a w id e r ra n g e of s y s t e m s f o r h a n d lin g s p a ti a l d a ta h a s b e e n a p r o d u c t o f
th e p a s t d e c a d e (1 9 6 4 -7 4 ), a n d e v e n now th e y m u s t b e c o n s id e r e d to b e in
a n e m b ry o n ic s ta g e of d e v e lo p m e n t.
1. B u rto n 1963. 2. C oppock 1962. 3. T o m lin s o n , R . F . 1962.
5. S c h m id t, A. 1966. 6. A m idon 1964. 7, T o b le r 1964a.
4. K ao 1963.
225
N ot o n ly w e r e g e o g ra p h ic in fo rm a tio n s y s t e m s n o t in th e f o r e f r o n t of th e
q u a n tita tiv e r e v o lu tio n in g e o g ra p h y , b u t a ls o th e y h a v e , in th e m a in , b e e n
d e v e lo p e d b y a g e n c ie s m o re c o n c e rn e d w ith th e h a n d lin g of d a ta th a n w ith
th e g ro w th of g e o g ra p h ic a l th e o ry .
I t is n o t w ith in th e s c o p e of th i s th e s i s
to r e p e a t o r e n la r g e on th e e p is te m o lo g ic a l p r o b le m s of g e o g ra p h y o r to
t r a c e th e o v e r a l l im p a c t o f q u a n tita tiv e m e th o d s on th e d e v e lo p m e n t o f g e o ­
g r a p h ic a l
th e o r y .
I t i s , h o w e v e r, n e c e s s a r y to m e n tio n b r ie f ly th e to p ic o f
g e o g r a p h ic a l m e th o d o lo g y to i l l u s t r a t e th e p o te n tia l c o n trib u tio n of
g e o g ra p h ic in f o r m a tio n s y s t e m s to f o r m a l s p a ti a l a n a ly s is .
A t th e o u ts e t, it i s p r o b a b ly r e a s o n a b le to s ta t e th a t th e a b ility to h a n d le
s p a ti a l d a ta w ill p r o b a b ly h a v e m o r e im m e d ia te im p a c t on g e o g ra p h ic a l
m e th o d o lo g y th a n on g e o g r a p h ic a l th e o r y .
W ith in a g e o g ra p h y d e fin e d a s
" th e d e s c r i p tio n a n d e x p la n a tio n of th e s p a ti a l d if f e re n tia tio n a n d in te r a c tio n
b e tw e e n a t tr ib u t e s o f th e e a r t h 's s u r f a c e , "1 t h e r e a r e a n u m b e r o f " s tr a n d s "
o f th e o r y , w h ic h a r e v e r y d iffic u lt to d is c u s s in th e a b s e n c e o f an y a s y e t
c l e a r ly id e n tif ie d b o d y of g e o g ra p h ic a l th e o ry .
H a g g e tt an d C h o rle y 2 h av e
a p p ro a c h e d th e p r o b le m b y g ro u p in g a w id e v a r i e t y of id e a s an d a p p r o a c h e s
w ith in a f r a m e w o r k of m o v e m e n ts , n e tw o rk s , n o d e s , h i e r a r c h i e s , and
s u rfa c e s.
T h e r e a r e p ro b le m s of d is tin c tly s p a ti a l d a ta a s s o c ia te d w ith e a c h
of th e s e " s t a g e s " , a n d s o m e of th e m h a v e b e e n a tta c k e d , c o n s c io u s ly o r n o t,
b y th e g e o g ra p h ic d a ta h a n d lin g s y s t e m s d e s c r ib e d .
Som e e x a m p le s at
v a r io u s s ta g e s a r e s y s t e m s b a s e d on p o in t d a ta , o n l i n e s e g m e n ts , o n i r r e g ­
u l a r p o ly g o n s , a n d
on
o th e r s u r f a c e - d e s c r ip ti v e f o r m a ts , an d s y s t e m s w ith
th e a b ility to c o m b in e a t tr ib u t e s w ith in o r b e tw e e n d a ta f o r m a ts a n d to d e r iv e
c o m p o s ite d a ta s u c h a s th e in te r a c tio n b e tw e e n tw o p la c e s , t h e i r h i e r a r c h ic a l
s ta t u s , o r t h e i r in v o lv e m e n t in a p a r t i c u l a r a c tiv ity .
T h e r e a r e , h o w e v e r,
d if fic u ltie s in th i s s im p l is tic r e la tio n s h ip b e tw e e n g e o g ra p h ic a l th e o r y an d
c a p a b ilitie s f o r h a n d lin g s p a ti a l d ata.
A s in an y d is c ip lin e , t h e r e a r e m a n y a p p r o a c h e s to th e o r y , ra n g in g f r o m
th e m o s t a b s t r a c t , d e d u c tiv e , and id e a liz e d m e n ta l c o n s tr u c ts of t h e o r e ti c a l
p h y s ic a l s c ie n c e o r e c o n o m ic s , to th e m o s t in d u c tiv e , d a ta - o r ie n te d
fo r m u la tio n of w o rk in g h y p o th e s e s , f o r th e p u r p o s e s o f e x p e rim e n ta l s c ie n c e
o r s o c ia l s tu d ie s .
T h e f o r m e r ty p e of a p p ro a c h o fte n d e a ls w ith c o n c e p ts
1. S u rfa c e in th i s s e n s e im p ly in g " s h e ll " , r a t h e r th a n th e m a th e m a tic a l
d e fin itio n of " s u r f a c e " . 2. H a g g e tt 1965, C h o rle y a n d H a g g e tt 1967, H a g g e tt
a n d C h o r le y 1969.
226
th a t a r e c u r r e n t l y d iffic u lt to m e a s u r e (su c h a s a "q u a n tu m " in p h y s ic s o r
" u tility " in e c o n o m ic s ), o r th a t c a n b e m a th e m a tic a lly p r e c i s e i n t h e i r
m e a n in g w h ile b e in g d iffic u lt to e n v is a g e i n th e r e a l w o r ld (fo r e x a m p le ,
e x p o n e n tia l fu n c tio n s , L a g r a n g ia n m u l tip l ie r s , o r e n tro p y ). T h e in d u c tiv e
a p p ro a c h , on th e o th e r h a n d , d ep e n d s on f o r m u la tin g g e n e ra liz a tio n s ( th e o r e ti­
c a l s ta te m e n ts ) in w a y s th a t c a n b e te s t e d th r o u g h m o d e ls of v a r io u s k in d s .
T h e in d u c tiv e a p p ro a c h , in f a c t, d e p e n d s o n th e a v a ila b ility of s p e c if ic d a ta .
T o c o m p lic a te th i s s itu a tio n f u r th e r , b o th d e d u c tiv e ly a n d in d u c tiv e ly d e r iv e d
th e o r ie s c a n b e t e s t e d b y r e f e r e n c e to m o d e ls t h a t u s e v a r io u s ty p e s o f s u r r o ­
g a te d a ta ; f o r e x a m p le , u ti lit y m a y b e m e a s u r e d b y th e a m o u n t o f c a s h p e o p le
a r e p r e p a r e d to p a y f o r a good; in te r a c tio n i s o f te n " m e a s u r e d " th r o u g h u s e
of s p e c if ic s e t s of d a ta on m ig ra tio n , te le p h o n e c a l l s , o r c o m m u tin g flo w s .
T h e v a lid ity of s u c h o p e r a tio n a l t e s t s o f t h e o r e t i c a l s ta te m e n ts o b v io u s ly
d e p e n d s on how w e ll th e d a ta c o n fo r m
d e r iv e d f r o m th e th e o r y .
w ith t h e a s s u m p tio n s o f th e m o d e l
T h u s th e d iffic u lty i n f o r m u la tin g a n y d ir e c t
m e a s u r e o f th e im p a c t of e x is tin g o r im p ro v e d g e o g ra p h ic in f o r m a tio n
s y s t e m s on th e c r e a tio n of g e o g ra p h ic a l t h e o r y c a n b e r e a d i ly a p p r e c ia te d .
H a rv e y ­1 a t te m p ts a b r i e f c la s s i f ic a t io n o f th e v a r i o u s a p p r o a c h e s to t h e o r e t i ­
c a l s t r u c t u r e s : T y p e 1, d e d u c tiv e ly c o m p le te th e o r y ; T y p e 2, s y s te m a tic
p r e s u p p o s itio n s ; T y p e 3, q u a s i- d e d u c tiv e t h e o r i e s (w hich in c lu d e s in d u c tiv e
s y s t e m a tiz a tio n a s o n e of i t s sub c a te g o r ie s ) ; a n d T y p e 4 , n o n fo rm a l th e o r ie s .
C o n s id e rin g s p e c i f ic a l ly g e o g ra p h ic th e o r y , H a r v e y 2 a r g u e s th a t
"G iv en th e
n a t u r e of g e o g r a p h ic a l c o n c e p ts , th e d e v e lo p m e n t of f o r m a l th e o r y (T y p e 1)
in g e o g ra p h y a p p e a r s to b e a r e s t r i c t e d p o s s i b i l i t y ," an d , "In p r a c t ic e ,
m o s t of o u r t r a d iti o n a l ( p r e - q u a n tita tiv e ) th e o r is in g h a s b e e n w ith in T y p e 4
th e o r e ti c a l s t r u c t u r e s . . . "
H e c o n tin u e s 3 b y s u g g e s tin g th a t
"in th e p r e s e n t
s itu a tio n , i t m a y w e ll b e m o re a d v is a b le to d e v e lo p c l e a r h e u r i s t ic tr e a tm e n ts
of g e o g r a p h ic a l p r o b le m s th a n to s e e k f o r f u l l f o r m a l e x p r e s s io n s o f th e o r y .
F o r th i s r e a s o n , m o d e l-b u ild in g te c h n iq u e s a r e m u c h m o r e s ig n ific a n t to
g e o g ra p h ic r e s e a r c h a n d a r e lik e ly to r e m a in s o in th e n e a r f u t u r e . "
F o llo w in g th i s lin e o f th o u g h t, it is r e a s o n a b le t o s u g g e s t th a t th e m a in c o n t r i­
b u tio n to b e m a d e b y g e o g ra p h ic in f o rm a tio n s y s t e m s to g e o g r a p h ic a l th e o r y
a n d f o r m a l s p a t i a l a n a ly s is is th e p r o v is io n o f d a t a f o r m o d e ls o r p a r t i a l
1. H a r v e y 1969, C h. 7, pp. 9 7 -9 9 .
3. H a r v e y 1969, C h. 9, p. 134.
2. H a r v e y 1 9 69, C h. 9, p . 130.
227
m o d e ls r e l a t e d to in d u c tiv e t h e o r e ti c a l s t r u c t u r e s .
T h e q u e s tio n th a t r e m a in s
i s w h e th e r m o d e ls of u s e in g e o g r a p h ic a l s tu d ie s r e q u i r e s p a tia lly d is a g g r e ­
g a te d d a ta , o r l a r g e v o lu m e s of d a ta , o r w h e th e r th e y r e q u i r e s o p h is tic a te d
te c h n iq u e s of m a n ip u la tio n to d e r iv e a d e q u a te s u r r o g a te d a ta f r o m b a s ic d a ta
s e ts ; in o th e r w o r d s , w h e th e r g e o g ra p h ic in f o rm a tio n s y s te m s a r e a c tu a lly
needed.
C e r t a in l y th e r e h a s b e e n l i t t l e c o m m u n ic a tio n b e tw e e n th o s e d e v e ­
lo p in g m o d e ls a n d th o s e d ev e lo p in g g e o g ra p h ic in fo rm a tio n s y s te m s .
F r e q u e n t ly o n e h e a r s of m o d e ls b e in g b a s e d o n e x is tin g d a ta , o r s im p ly
u s in g s p e c i a l s u r v e y s to g a th e r d a ta o th e r w is e u n a v a ila b le .
T h e o v e r a l l s p e c t r u m of d a ta n e e d s f o r g e o g ra p h ic a l m o d e ls h a s n o t b e e n
e x a m in e d e x te n s iv e ly .
A p a rt f r o m s t a t i s t i c a l a b s t r a c t s an d r e p o r t s o n d a ta
s o u r c e s , s o m e p u b lic a tio n s b y d a ta g a th e r in g in s titu tio n s h a v e s u g g e s te d
u s e s f o r th e d a t a th e y c o lle c t.
A n e x a m p le of th e s e i s a s e r i e s 1 o f p u b lic a ­
tio n s b y th e U. S. B u r e a u of C e n s u s o n d a ta u s e f o r v a rio u s ty p e s o f a d m in i­
s tra tiv e p u rp o se .
S im ila r ly , th e a d m in is tr a tiv e n e e d s of p la n n in g a g e n c ie s
f o r d a ta h a v e b e e n e x a m in e d ; th i s w o rk i s ty p if ie d b y th e p a p e r s of
C h e s h ir e 2 in G r e a t B r it a in , H o lle b 3 in th e U. S. A., S a lo m o n ss o n 4 in Sw eden,
a n d b y a m a jo r s tu d y 5 in G r e a t B r i t a i n th a t e x a m in e d th e n e e d s o f lo c a l
a g e n c ie s in t e r m s of th e d e c is io n s th e y m a k e .
T h e l a s t s tu d y d id n o t,
h o w e v e r, r e l a t e th e d a t a to th e s t i l l " la r g e ly e x p e rim e n ta l s y s t e m s a p p ro a c h
to p la n n in g a n d m o d e llin g te c h n iq u e s ." A t th e o th e r en d of th e s c a l e a r e
th e n u m e ro u s d e s c r i p tio n s of in d iv id u a l s p a t i a l m o d e ls th a t m e n tio n th e d a ta
p r o b le m s r e l a t e d to t h e i r s p e c ific t a s k .
p o in t o f v ie w .
S om e a u th o r s h a v e ta k e n a w id e r
C o ppock a n d J o h n so n 6 in 1962 m a d e a n e a r l y e x a m in a tio n o f
d a ta s o u r c e s i n t e r m s o f th e b u rg e o n in g d e m a n d s of q u a n tita tiv e g e o g ra p h ic a l
m e th o d s .
R e c e n t w o r k i s ty p ifie d b y th e r e p o r t s o f C a t e r ,7 B a tty ,8 an d
W illis 9 in th e U n ite d K ingdom .
O f th i s l a t e r w o rk , th a t o f B a tty p r o b a b ly
a p p r o a c h e s th e p r o b le m m o s t d ir e c tly .
B a tty c o n s id e r s th e s p a ti a l t h e o r y u n d e rly in g u rb a n p la n n in g an d g e n e ra lly
c l a s s i f i e s th e v a r i o u s c o n c e p ts a c c o rd in g to t h e i r u s e of d a ta .
H e r e c o g n iz e s
e ig h t c a te g o r ie s , b a s e d o n w h e th e r th e d a ta u s e d a r e a g g re g a te d o r d is a g g r e ­
g a te d w ith r e s p e c t to s p a c e , a ttr ib u t e , o r tim e .
T h e s e c a te g o r ie s c a n b e
g ro u p e d a n d ra n k e d a c c o rd in g to th e le v e l of r e s o lu tio n of th e d a ta
1. U. S. B u r e a u of C e n s u s 1970a. 2. C h e s h ir e 1970. 3. H o lle b 1969.
4 . S a lo m o n ss o n 1969. 5. M in is try of H o u sin g a n d L o c a l G o v e rn m e n t, U. K . 1970.
6. C o ppock a n d J o h n s o n 1962. 7. C a t e r 1970. 8. B a tty 1970. 9. W illis 1971.
228
e m p lo y e d .
F o r co n v e n ie n c e of c l a s s i f ic a t io n , low le v e ls o f d a ta r e s o lu tio n
w ill b e r e f e r r e d to a s " r e l a tiv e ly a g g re g a te d " d a ta an d h ig h le v e ls of
re s o lu tio n a s " r e l a tiv e ly d is a g g re g a te d " d ata.
T h e co n c e p t of a g g re g a tio n o r d is a g g re g a tio n of th e s p a ti a l a s p e c t o f d a ta
g e n e ra lly r e l a t e s to s c a le .
R e la tiv e ly a g g r e g a te d d a ta in th e s p a ti a l s e n s e
w o u ld b e u s e d in s u b r e g io n a l m o d e ls s u c h a s i n t e r u r b a n m o d e ls , w h e r e a s
r e l a ti v e ly d is a g g r e g a te d s p a ti a l d a ta w o u ld b e e m p lo y e d in i n t r a - u r b a n
m o d e ls a t lo c a l s c a l e s .
In t e r m s of ti m e d a ta , m o d e ls th a t a r e s ta t ic w ith r e s p e c t to ti m e a r e
c o n s id e r e d to e m p lo y a g g re g a te d ti m e d a ta ; c o n v e rs e ly , th o s e th a t a r e
d y n a m ic w ith r e s p e c t to tim e a r e s a id to b e u s in g d is a g g re g a te d ti m e d a ta .
S im ila r ly , th e r e l a ti v e a g g re g a tio n o r d is a g g re g a tio n of a t tr ib u t e d a ta r e f e r s
to th e le v e l of d e ta il a t w h ich th e y a r e c la s s if ie d .
In m o d e ls u s in g p o p u la tio n
o r e m p lo y m e n t d a ta , f o r e x a m p le , a g g r e g a tio n w ould a p p ly to th o s e th a t
t r e a t th e d a ta a s a w h o le w h e r e a s d is a g g r e g a tio n w o u ld a p p ly to m o d e ls th a t
s u b d iv id e th e m in s o m e w ay.
T h e ra n k in g of m o d e ls i s g iv e n b elo w .
(B a tty u s e s a d iffe re n t f o r m a t f o r th e
a r r a n g e m e n t of h is e ig h t c a te g o r ie s a n d a s o m e w h a t d iff e re n t a s s ig n m e n t of
c o n c e p ts to c a te g o r ie s , b u t th e g e n e ra l a p p ro a c h fo llo w s h is w o r k .)
L e v e l 1:
A ll d a ta a g g r e g a te d in s p a c e , a ttr ib u t e , a n d tim e
E x a m p le s : R an k s iz e r u le , g r a v ity th e o r y ( p r in c ip le o f l e a s t e ffo rt).
L e v e l 2:
O ne a s p e c t of d a ta d is a g g re g a te d ; o th e r a s p e c ts a g g r e g a te d
a) D is a g g r e g a te d s p a ti a l d a ta
E x a m p le s ; T h e o r ie s o f li n e a r f o r m , c o n c e n tr ic f o r m , a n d
m ic r o s c a le d e s ig n , c e n tr a l p la c e th e o r y , G a r in L o w ry m o d e ls of ch a n g e of la n d u s e .
b) D is a g g r e g a te d a t tr ib u t e d a ta
E x a m p le s: I s a r d 's g e n e ra l th e o r y of s p a ti a l e c o n o m ic s (m in im u m
c o s t e q u ilib riu m ), e c o n o m ic b a s e th e o r y , in p u t-o u tp u t
a n a ly s is , s o c ia l th e o r y of h u m a n in te r a c tio n (e. g . ,
W e b b e r), F o r r e s t e r 's m o d e l of u r b a n d y n a m ic s ,
M e ie r 's m o d e l of h u m a n co m m u n ic a tio n .
c) D is a g g r e g a te d tim e d a ta
E x a m p le s : M ig ra tio n m o d e ls (e. g . , H äg e r s tr a n d ) .
229
L e v e l 3:
T w o a s p e c t s of d a ta d is a g g r e g a te d , t h i r d a g g re g a te d
a ) D is a g g r e g a te d s p a tia l d a ta , d is a g g r e g a te d a ttr ib u te d a ta
E x a m p le s : S o c io -e c o lo g ic a l th e o r ie s (la n d u s e - la n d r e n t e q u i­
lib r iu m ) s u c h a s th e c o n c e n tr ic zone th e o r y , m u ltip le
n u c le i an d s e c t o r a l th e o ry , ec o n o m ic r e n t , th e o r y of
a g r i c u lt u r a l lo c a tio n an d u r b a n lo c a tio n , W in g o 's
m o d e l of u r b a n la n d u s e , M u th 's m o d e l o f r e s id e n tia l
lo c a tio n , K a in 's m o d e l of r e s id e n tia l lo c a tio n , H e r b e r t S te v e n s ' m o d e l of r e s id e n tia l lo c a tio n , C h a p in -W e is s '
m o d e l of r e s id e n tia l lo c a tio n , e tc .
b) D is a g g re g a te d s p a tia l d a ta , d is a g g r e g a te d tim e d a ta
E x a m p le s : S p a tia l d iffu sio n m o d e ls .
c) D is a g g r e g a te d a ttr ib u te d a ta , d is a g g re g a te d ti m e d a ta
E x a m p le s : R e g io n a l e c o n o m e tric m o d e ls .
L ev el 4:
A ll d a ta d is a g g r e g a te d in s p a c e , a t tr ib u t e , an d tim e
E x a m p le :
I s a r d 's g e n e ra l th e o ry .
E x a m in a tio n o f th e le v e l of d a ta r e q u ir e m e n t of th e v a r io u s c o n c e p ts i l l u s ­
t r a t e s th a t, f o r th e e x a m p le s of u r b a n s p a ti a l th e o r y g iv e n , th e a v a ila b ility
of d a ta d o e s n o t a f fe c t th e c o n c e p tu a l f o r m a tio n of th e o ry .
L e v e l 1 c o n ta in s s o m e o f th e m o r e f re q u e n tly d is c u s s e d th e m e s o f r e c e n t
q u a n tita tiv e g e o g ra p h y , th o s e of r a n k s iz e r u le an d g r a v ity th e o r y (p rin c ip le
o f l e a s t e f f o r t) .
an d 1949.1
T h e s e c o n c e p ts w e r e , h o w e v e r, f o rm u la te d b e tw e e n 1929
T h e y w e r e ta k e n up a g a in b y s e v e r a l w o r k e r s b e tw e e n 1956 and
1964 . 2
L e v e l 2 c o n ta in s t h r e e c a te g o r ie s , e a c h w ith so m e w h a t d if f e re n t c h a r a c t e r i s ­
tic s .
T h e f i r s t c a te g o r y c o n ta in s th e o r ie s of li n e a r f o r m a n d c o n c e n tr ic
f o r m e l a b o r a te d b y w o r k e r s in th e a r c h i te c tu r a l tr a d iti o n a c tiv e a t th e tu r n o f
th e c e n tu ry .
T h e s e c l a s s i c s tu d ie s in c lu d e G a r n i e r 's c o n c e p t o f th e li n e a r
f o r m , " C ité i n d u s t r i e l l e , " p ro p o s e d in 1904, E b e n e z e r H o w a rd 's c o n c e p t of
a c o n c e n tr ic f o r m of " G a rd e n C ity " in 1898, a n d L e C o r b u s ie r 's c o n c e p t of
th e " V ille r a d i e u s e " in 1920.
T h e c a te g o r y a ls o c o n ta in s w o rk o f t h e ir
m o d e r n c o u n t e r p a r ts 3 in m i c r o s c a le u r b a n d e s ig n , p u b lish e d b e tw e e n 1964
an d 1967, th e c o n c e p ts of c e n tr a l p la c e th e o r y , a n d th e G a r in - L o w r y m o d e ls
o f la n d u s e c h a n g e .
T h e f i r s t of th e s e c o n c e p ts o r ig in a te d o v e r 40 y e a r s ag o 4
a n d h a s b e e n d e v e lo p e d m o r e r e c e n tly (1954-67) b y s e v e r a l w o r k e r s .5
The
1. R e illy 1929, S in g e r 1936, Z ip f 1949. 2. C a r r o t h e r s 1956, B e r r y an d G a r r is o n
1958, B e r r y 1 9 6 1 , K a n to ro w ic h 1964, H uff 1964, an d o th e r s . 3. A le x a n d e r
1964, 1967, A le x a n d e r a n d C h e rm a y e ff 1966. 4. C h r is ta lle r 1935. 5. L o s c h
1954, B e r r y 1967.
230
G a r in - L o w r y m o d e ls o f la n d u s e ch a n g e a tte m p t to u s e v e r y d is a g g r e g a te d
s p a t i a l d a t a a n d a r e r e l a ti v e ly r e c e n t d e v e lo p m e n ts .1
T h e s e c o n d c a te g o r y of le v e l 2 c o n ta in s th e o r ie s e s s e n ti a ll y d e r iv e d f r o m
e c o n o m ic s a n d th e s o c ia l s c ie n c e s .
A ll a r e d a ta - d e p e n d e n t th e o r ie s an d
w e r e d e v e lo p e d b e tw e e n 1956 a n d 1969 by n u m e ro u s w o r k e r s .2
T h e t h i r d c a te g o r y c o n ta in s th e o r y c h a r a c te r iz e d b y d is a g g r e g a te d tim e
d a ta a n d g e n e r a lly l a r g e v o lu m e s of d a ta .
W o rk on m ig r a tio n m o d e ls b y
g e o g r a p h e r s w a s a d e v e lo p m e n t of th e p e r io d 1957-69.3
L e v e l 3 c o n ta in s t h r e e c a te g o r ie s , th o u g h m o s t of th e e x a m p le s f a l l in to th e
f i r s t w h ic h c o n ta in s c o n c e p ts em p lo y in g d a ta d is a g g r e g a te d in a t tr ib u t e an d
in s p a c e .
H e r e a g a in , i t c a n b e n o te d th a t th e a v a ila b ility of d a ta d o e s n o t
a ffe c t th e c o n c e p tu a l fo r m a tio n o f th e o ry .
w e r e d e v e lo p e d b e tw e e n 1925 a n d 1939.4
T h e s o c io -e c o n o m ic t h e o r i e s
T h e c l a s s i c th e o r y o f e c o n o m ic
r e n t w a s f i r s t f o r m u la te d b y R ic a rd o in 1817, a n d th e o r ie s o f a g r i c u lt u r a l
lo c a tio n a n d u r b a n lo c a tio n w e r e d ev e lo p ed b e tw e e n 1826 a n d 1926.5
The
m a in d e v e lo p m e n t of th e s e th e o r ie s a n d t h e i r e x te n s iv e te s t in g a n d d e v e lo p ­
m e n t, h o w e v e r , o c c u r r e d b e tw e e n 1961 a n d 1964.6
W ils o n 's 7 te c h n iq u e
o f e n tr o p y m a x im iz a tio n sh o u ld p e r h a p s b e r e g a r d e d a s a s p e c i a l c a s e , in
th a t th e a p p ro a c h is fle x ib le enough to b e u s e d w ith w id e ly v a r y in g le v e ls of
d is a g g r e g a tio n a n d ty p e s of d a ta .
T h e m o re f re q u e n t a p p lic a tio n s , h o w e v e r,
m ig h t b e a llo c a te d to th i s c a te g o ry .
T h e s e c o n d a n d t h i r d c a te g o r ie s a t th i s le v e l b o th r e q u i r e d a ta d is a g g r e g a te d
w ith r e s p e c t to ti m e .
C o u p le d w ith e i th e r d is a g g r e g a te d s p a ti a l d a ta o r d i s ­
a g g r e g a te d a t tr ib u t e d a ta , th i s im p lie s th a t s ig n ific a n t v o lu m e s o f d a ta m u s t
b e h a n d le d .
W o rk b y g e o g ra p h e rs in th is f ie ld i s a f a i r l y r e c e n t d e v e lo p m e n t;
th e s p a t i a l d iffu s io n m o d e ls of Hä g e r s tr a n d 8 a n d P i t t s 9 w e r e a p r o d u c t of
1. L o w ry 1964, 1965, G a rin 1966. 2. I s a r d 1956, 1960, L e o n tie ff a n d S tro u t
1963, W e b b e r 1963, 1964, W ils o n , A. G. 1967, 1969a, 1969b, N o u r s e 1968,
W ä r n e r y d 1968, B ro a d b e n t 1969, R ic h a r d s o n 1969, F o r r e s t e r 1961, M e ie r
1962, a n d o th e r s . 3. Hä g e r s tr a n d 1957, 1965, B o g u e 1957, R o g e r s 1968,
M o r r ill 1965, a n d o th e r s . 4. B u r g e s s 1925, M cK en zie 1933, H oyt 1933, 1939.
5. H u rd 1903, V on T h u n e n 1826, H aig 1926. 6. A lo n s o 1964, C h is h o lm 1961,
H a ll, 1966, W ingo 1961a, 1961b, M uth 1961, K ain 1962, H e r b e r t a n d
S te v e n s 1960, C h ap in a n d W e is s 1962a, 1962b, a n d o th e r s . 7 . W ils o n , A . G. 1969 c .
8. Hä g e r s t r a n d 1965. 9. P i t t s 1963.
231
th e e a rly 1 9 6 0 s . M o d e ls o f re g io n a l e c o n o m ic g ro w th 1 a re m o re
re c e n t, a n d so m e o f th e v e ry re c e n t w o rk o n u rb a n h o u s in g s u c h a s th a t
u n d e r d e v e lo p m e n t b y th e U rb a n In s titu te a n d th e N a tio n a l
B u rea u
fo r E c o n o m ic R e se a rc h in W a s h in g to n , D .C ., w o u ld s e e m to fa ll in to th is
category. L e v e l 4 c o n ta in s th e c a te g o r y o f th e o r y w h e r e th e d e m a n d s f o r d a ta
h a n d lin g a r e n e c e s s a r ily h ig h . I t
is ty p i f ie d b y c u r r e n t c o n c e p ts s u c h
as Isard's general
theory. S e v e ra l s u g g e s tio n s c a n b e m a d e fr o m th e a b o v e o b s e r v a tio n s . F ir s t,
a n d m o st o b v io u s, is th a t th e c o n c e p tu a l fo rm a tio n o f th e o ry is n o t d e p e n d e n t
o n th e a b ility to h a n d le d a ta . S e c o n d ly , th e te stin g o f h y p o th e se s b a s e d o n
s u c h th e o r ie s b y m o d e l b u ild i n g r e c e iv e d c o n s id e r a b le im p e t u s b e tw e e n
1 9 5 4 a n d 1 9 6 7 , a n d to s o m e e x te n t is c o n te m p o ra ry w ith th e a v a ila b ility
o f c a lc u la tin g c a p a c ity in
c o m p u te r s . T h i r d l y , th e t r e n d in m o r e r e c e n t w o r k
(1 9 6 1 -6 9 ) is to w ard d ata-d ep en d e n t m o d e ls, w h ic h c o u ld b e n e fit fro m in c re a s e d
availa­ bility of relevant data. F inally, the developm ent of theory req u irin g th e
a n a ly s is o f d a ta d isa g g re g a te d in tim e h a s n o t b e e n e x te n s iv e , a n d th is
is p o s sib ly d u e
in p a r t to t h e la c k o f s u i ta b l e d a t a a n d th e c a p a c ity t o h a n d le
them . F r o m t h e a b o v e c o m m e n t s i t i s c l e a r t h a t t h e d e v e l o p m e n t o f
g e o g r a p h ic in f o r m a tio n s y s te m s w ill n o t c r e a te th e o r y , b u t th e y m a y s p e e d
th e c o u r s e o f th e o r y te s tin g a n d th u s a llo w n e w a v e n u e s to b e
e x p lo re d
m o re ra p id ly . S p e c ific a lly , th e y m a y h e lp th e o ry b y m a k in g a v a ila b le in fo rm a tio n
that would: a ) a llo w c u r r e n t m o d e ls to b e te s te d o v e r a w id e r a r e a , o r f o r
more disaggregated populations;
b ) a l lo w th e d e v e lo p m e n t o f n e w m o d e ls ( o f te n d e r iv e d f r o m o ld th e o r y )
th a t m a y in c o r p o r a te v a r ia b le s n o t b e f o r e a v a ila b le in q u a n tita tiv e
fo rm (w h ic h m a y , in tu r n , le a d to c o m p le te ly n e w ty p e s o f th e o r e tic a l
development); c)
a s a s p e c i a l c a s e o f ( b ) a b o v e , p r o v i d e d a ta o n c h a n g e a t p la c e s , a n d th e
in te r r e la tio n s h ip b e tw e e n c h a n g e s a t p la c e s ( th a t is , th e in te r a c tio n
b e tw e e n a ttrib u te a n d tim e o v e r s p a c e ) , to d e v e lo p a n d im p r o v e
d y n a m ic m o d e ls o f in n o v a t io n , d if f u s io n , t h e la g g e d e f f e c t s
of econom ic and social change, etc.
1. R ic h a r d s o n 1969.
232
T h e a b o v e d is c u s s io n h a s b r ie f ly e x a m in e d th e re la tio n s h ip b e tw e e n f o r m a l
s p a ti a l a n a ly s is a n d th e a v a ila b ility of d a ta .
T h e n ex t s e c tio n w ill o u tlin e th e
c h a r a c t e r i s t i c s of th e d e c is io n -m a k in g p r o c e s s in g o v e rn m e n t.
T h e r e a f te r ,
th e v a lu e of e x is tin g g e o g ra p h ic in f o rm a tio n s y s te m s to f o r m a l s p a ti a l
a n a ly s is a n d d e c is io n m a k in g w ill b e e x a m in e d .
G O V ER N M EN T D ECISION MAKING R E L A T E D T O DATA U SE
T h e p r i m a r y fu n c tio n of m a n i s th e p r o c e s s in g of in fo rm a tio n .
A ll h is
d e c is io n s a r e b a s e d on h is im a g e of r e a l it y , h is m e n ta l m o d e l o f th e r e a l
w o r ld .
W h e re th e d e c is io n s (of a g o v e rn m e n t, f o r ex a m p le) c o n c e r n
v a r i a b le s d is tr i b u te d in s p a c e , th e th o u g h t p r o c e s s e s in v o lv ed a r e , to s o m e
d e g r e e , s p a t i a l m o d e ls .
M e n ta l m o d e ls can b e v e r y c o m p le x , f in e ly tu n e d ,
in tu itiv e p r o c e s s e s ; th e y r e c e iv e d a ta f r o m a v a r i e ty of s o u r c e s , f it th e m
in to th e in d iv id u a l's p r a g m a ti c e x p la n a tio n of th e c o u r s e s of a c tio n o p e n to
h im , a n d f o r m th e s ta n d p o in t f r o m w h ic h h e (as a M in is te r of g o v e rn m e n t
in C a b in e t, f o r e x a m p le ) m u s t a r g u e h is c a s e w ith h is c o lle a g u e s .
The
d is c u s s io n p r o c e s s of C a b in e t i t s e l f c o u ld b e lik e n e d to a n it e r a t iv e m o d e l,
r e c e iv in g v a r i a b le in p u ts of in fo rm a tio n a s th e d e b a te c o n tin u e s , p o s itio n s
(w eig h ted v a r i a b le s ) a r e c h a n g e d in d e b a te , and an e v e n tu a l s o lu tio n (o r la c k
of one) i s r e a c h e d .
I t i s n o t s u g g e s te d th a t th i s i s a co ld , r a t io n a l p r o c e s s .
A ny e x p e r ie n c e of th e p o li tic a l o r e m o tio n a l a s p e c ts of d e c is io n m a k in g
im m e d ia te ly in f o r m s o n e o th e r w is e .
T h e p s y c h o lo g ic a l im p u ts s im p ly a d d
to t h e ra n g e of in fo rm a tio n b e in g p r o c e s s e d ; th e y a r e a n in t e g r a l p a r t o f th e
d e c is io n - m a k in g p r o c e s s a n d i n c r e a s e th e c o m p le x ity of th e in h e r e n t m o d e llin g
e x e rc is e .
T h e r e a r e no f o r m a l s u r r o g a t e s th a t c a n a d e q u a te ly r e p l a c e th e
m e n ta l m o d e llin g p r o c e s s in 1974, th o u g h o b v io u sly b o th f o r m a l an d m e n ta l
m o d e ls c a n p la y a r o l e in d e c is io n - m a k in g p r o c e s s e s .
T h e m e n ta l m o d e ls
r e l y o n d a ta p r e s e n t e d in s u c h a w ay th a t th e h u m a n m in d c a n v is u a liz e an d
c o m p re h e n d th e m .
T h u s , th e r o l e o f in fo rm a tio n s y s te m s f r e q u e n tly i s to
r e d u c e , d e r iv e , a n d r e f o r m a t d a ta s o th a t th e y c a n b e u n d e rs to o d a n d
i n c o r p o r a te d in th e m e n ta l m o d e llin g p r o c e s s (th e p a r a l l e l r o le f o r in f o r m a ­
tio n s y s t e m s i s to s u p p ly a n d m a n ip u la te d a ta f o r in p u t to f o r m a l m o d e ls ).
E v e n a m o n g g o v e rn m e n ta l in s ti tu ti o n s , i t i s e a s y to e n v isa g e a w id e r a n g e
o f ty p e s o f d e c is io n - m a k in g a g e n c y .
A ty p ic a l s e t of d e c is io n - m a k in g
233
in s ti tu ti o n s i s g iv e n in F ig . 7. 2.
E x a m p le s
UN
C a th o lic c h u r c h
G lo b a l
NATO
OPEC
M u ltin a tio n a l
C anada
N a tio n a l
TVA
M a r itim e s
S ta te
P ro v in c e
R e g io n a l
L ocal
C o u n ty
C ity
C o m m u n ity
In d iv id u a l
F a m ily
P e rso n
F ig . 7. 2.
T y p ic a l s e t of d e c is io n -m a k in g in s titu tio n s .
T h e l i s t i s a r b i t r a r y a n d o th e r s e t s of d e c is io n -m a k in g a g e n c ie s c o u ld b e
e q u a lly v a lid ; one co u ld d iffe re n tia te b e tw e e n g o v e rn m e n ts in c o u n tr ie s a t
d if fe re n t s ta g e s of e c o n o m ic d e v e lo p m e n t, f o r e x a m p le , o r b e tw e e n g o v e r n ­
m e n ts w ith d if fe re n t p o litic a l an d a d m in is tr a tiv e p h ilo s o p h ie s .
T he lis t
a b o v e r e c o g n iz e s g lo b a l, m u ltin a tio n a l, n a tio n a l, r e g io n a l, lo c a l, an d
in d iv id u a l le v e ls of d e c is io n m a k in g .
T h e ty p e s of d e c is io n - m a k in g
a g e n c ie s a n d th e ty p e s of d e c is io n w ith in in s titu tio n s th a t f a l l in to th e s e
c a te g o r ie s ca n b e r e a d i ly e n v isa g e d .
T h e a i m i s n o t to d efen d th i s p a r t ic u l a r
s e t , b u t m e r e ly to in d ic a te th e s c o p e of a n y s tu d y of d e c is io n m a k in g in
g o v e rn m e n t.
If th i s s e t is a c c e p te d a n d o n ly th e n a tio n a l, r e g io n a l, a n d lo c a l
f o r m s of g o v e rn m e n t a r e c o n s id e re d , one c a n s u g g e s t s o m e of th e ty p e s of
d e c is io n m a d e b y s u c h a g e n c ie s (F ig . 7. 3).
P o lic y
S e le c tio n b e tw e e n
a lte rn a tiv e s
M anagem ent
S e le c tio n o f im p le m e n ta tio n
a lte r n a tiv e s w ith in p o lic y
a n d o th e r c o n s tra in ts
A d m in is tra tiv e /
m o n ito r in g p r o c e s s e s
D a y - to - d a y d e c is io n s w ith in
c h o s e n im p le m e n ta tio n p r o c e d u r e
F ig . 7. 3.
T y p ic a l ty p e s of d e c is io n w ith in n a tio n a l, r e g io n a l, a n d lo c a l
in s titu tio n s .
234
T h e l i s t c h o s e n d if f e r e n tia te s b etw e en ty p e s of d e c is io n s in a r e a s o f p o lic y ,n
m a n a g e m e n t, an d th e a d m in is tr a tiv e /m o n ito r in g p r o c e s s .
T h e c a te g o r ie s
a r e s u b je c tiv e a n d th e a c tu a l b o u n d a ry c o n d itio n s th a t s e p a r a t e th e m a r e
f a r f r o m d is tin c t; o th e r s e t s of d e c is io n ty p e s c a n b e e q u a lly v a lid .
T hus,
D e u ts c h 1 r e v ie w s s e v e r a l m o d e ls o f p o litic a l c o m m u n ic a tio n a n d c o n tr o l in
g o v e rn m e n t, B r a y 2 r e c o g n iz e s g e n e ra l p o lic y r e v ie w s , a c tio n p r o g r a m s ,
a n d o p e r a tio n a l d e c is io n s a s s e p a r a t e c a te g o r ie s w ith in th e B r i t i s h g o v e r n
m e n t, a n d W a rd 3 in C a n a d a h a s d is c u s s e d g o v e rn m e n t d e c is io n s d if f e r e n ­
t i a t e d on f i s c a l c r i t e r i a .
A g ain , th e a im i s n o t to d e fe n d th e s e t p r e s e n t e d
a b o v e , b u t to in d ic a te th e s c o p e of th e ty p e s of d e c is io n th a t m u s t b e
c o n s id e r e d f o r f u tu r e stu d y .
In th e c a te g o r ie s g iv e n a b o v e , p o lic y d e c is io n s
a r e ta k e n to b e th o s e w h e r e a s e le c tio n is m a d e b e tw e e n m a jo r a l te r n a t iv e s
o f a c tio n .
M a n a g e m e n t d e c is io n s c o n c e rn th e s e le c tio n o f a lte r n a t iv e s f o r
im p le m e n tin g th a t p o lic y w ith in th e c o n s tr a in ts of th e p o lic y a n d th e j u r i s ­
d ic tio n a l c o n s tr a in ts of th e a g e n c y r e s p o n s ib le f o r im p le m e n ta tio n .
D e c isio n s
o n a d m in is tr a tiv e a n d m o n ito rin g p r o c e s s e s a r e th e d a y - to - d a y d e c is io n s
w ith in th e c h o s e n im p le m e n ta tio n p r o c e d u r e s .
A h y p o th e tic a l p o lic y d e c is io n a t th e n a tio n a l le v e l of g o v e rn m e n t, f o r
e x a m p le , c o u ld b e to r e h a b i li ta te f a r m e r s f r o m m a r g in a l f a r m s w h o se
in c o m e w a s b elo w th e p o v e r ty le v e l.
T h e p o s s ib le ju r i s d i c ti o n a l, le g a l,
f in a n c ia l , a n d s p e c if ic m e a s u r e s w o u ld b e e s ta b lis h e d .
T h e p o lic y m ig h t
s p e c i f y a v a r i e t y of m e a s u r e s s u c h a s f a r m p u r c h a s e , fo r m a tio n o f f a r m e r s '
c o o p e ra tiv e s , a m a lg a m a tio n of f a r m s in to e c o n o m ic a lly v ia b le e n titie s ,
in c r e a s e d o p p o rtu n itie s f o r e x te n s io n e d u c a tio n in a g r i c u lt u r e , d ir e c t
c a p ita l s u p p o r t, s u b s i d ie s f o r c ro p tr a n s p o r t a ti o n , a n d s o f o r th .
The
m a n a g e m e n t d e c is io n s r e l a t e d to s u c h p o lic y m ig h t b e c o n c e rn e d , in th e f i r s t
in s ta n c e , w ith id e n tify in g f a r m e r s on m a r g in a l la n d .
in v e n to r y o f m a r g in a l la n d .
T h is m ig h t in v o lv e an
In a c o u n tr y w ith th e re g io n a l d iv e r s i ty of
C a n a d a , f o r e x a m p le , a m a n a g e m e n t d e c is io n m a y b e m a d e , on th e b a s i s
o f v a r i o u s ty p e s of d a ta , to em p lo y (p ro m o te an d e n c o u ra g e ) o n e c o u r s e of
a c tio n in o n e p a r t of th e c o u n tr y a n d a n o th e r in a d iffe re n t p a r t o f th e
c o u n try .
A d m in is tr a tiv e d e c is io n s w ould b e a t th e le v e l o f d e te r m in in g
w h e th e r a f a r m e r w a s e lig ib le f o r s u p p o rt u n d e r th e v a r io u s c a te g o r ie s of
l . D e u ts c h 1966.
2. B r a y 1970.
3. W a rd 1962.
23 5
th e le g is la t io n im p le m e n te d in h is a r e a ; th e y w o u ld in c lu d e m o n ito rin g th e
p r o c e s s , m e a s u r in g th e r e s p o n s e to th e p r o g r a m in th e a r e a , a n d s o fo rth .
T h e d e c is io n -m a k in g le v e ls a r e O bviously in te rd e p e n d e n t an d o p e r a te w ith in
a c o m p le x fr a m e w o r k w ith in an d o u ts id e th e in s titu tio n s .
A s im p l is tic
co n ­
c e p t o f th e r e la tio n s h ip s b e tw e e n th e d e c is io n -m a k in g le v e ls of n a tio n a l,
re g io n a l, a n d lo c a l g o v e rn m e n ts in a p a r l ia m e n ta r y s y s t e m is il lu s tr a t e d
in th e d ia g r a m ( F ig . 7 .4 ) o v e r le a f .
T h e d ia g r a m a n d th e c o m m e n ts th a t
follow a r e a s g e n e ra l a s p o s s ib le , b u t r e f l e c t th e a u t h o r 's e x p e rie n c e w ith
v a r io u s le v e ls of p a r l ia m e n ta r y g o v e rn m e n t in C an a d a.
T h e h y p o th e tic a l le g is la t io n a l r e a d y o u tlin e d w ill b e u s e d a s an e x a m p le to
t r a c e th e p a th s fo llo w e d b y th e d e c is io n -m a k in g p r o c e s s a s p r e s e n t e d in th e
d ia g r a m (F ig . 7 .4 ).
T h e p o s s ib le c o n trib u tio n of g e o g ra p h ic in fo rm a tio n
s y s t e m s a n d f o r m a l a n d m e n ta l m o d e ls to th e p r o c e s s w ill a l s o b e e x a m in e d .
I t m u s t, h o w e v e r, b e e m p h a s iz e d th a t th e m ix tu r e an d v a lu e of th e v a r io u s
te c h n iq u e s a r e d if fe re n t f o r e a c h ty p e of le g is la tio n ; th e y v a r y f r o m y e a r to
y e a r , f r o m d e p a rtm e n t to d e p a rtm e n t, a n d e v e n f r o m in d iv id u a l to in d iv id u a l
a c c o r d in g to th e tr a in in g a n d c h a r a c t e r of k e y p e r s o n n e l.
A s s u m in g th a t th e d ia g r a m r e p r e s e n t s a n a tio n a l le v e l of g o v e rn m e n t an d th e
p o lic y d e c is io n r e s u l t s in p a r l ia m e n ta r y le g is la tio n , th e A ct w ill u s u a lly b e
im p le m e n te d b y a s in g le g o v e rn m e n t d e p a rtm e n t, th o u g h it m a y a l s o h a v e an
im p a c t o n th e a c tio n s o f o th e r s .
T h o s e in v o lv e d w ith th e m a n a g e m e n t d e c is io n
p r o c e s s a s d e fin e d ab o v e a r e now r e s p o n s ib le f o r c h o o s in g th e a lte r n a tiv e s
o f a c tio n w ith in th e le g is la t iv e f ra m e w o r k .
F o r o u r h y p o th e tic a l a g r i c u lt u r a l
le g is la tio n , th e d e p a rtm e n t m a y f i r s t w a n t to g a th e r d a ta , n o t a v a ila b le f r o m
o th e r s o u r c e s , a b o u t th e d is tr i b u tio n of m a r g in a l la n d s a c r o s s th e co u n try .
T h is s te p i s sh o w n a s in p u t f r o m d e p a rtm e n ta l d a ta g a th e r in g to th e m a n a g e ­
m e n t d e c is io n p r o c e s s .
A g e o g ra p h ic in f o rm a tio n s y s t e m m a y b e d e s ig n e d ,
o r a n e x is tin g o n e u s e d , to s t o r e , m a n ip u la te , a n d g e n e r a te s u m m a r ie s of
th e d a t a f o r th e d e p a rtm e n t.
D a ta f r o m o th e r a g e n c ie s , s u c h a s a g r i c u lt u r a l
c e n s u s d a ta r e l a ti n g to s iz e a n d c o n d itio n of f a r m s , g r o s s p ro d u c tiv ity ,
a v e r a g e in c o m e le v e ls , a n d s o f o r th , m a y b e d e riv e d a n d r e w o r k e d to m a tc h
th e d a ta g a th e r e d b y th e im p le m e n tin g a g e n c y it s e lf .
At th i s s ta g e , f o r m a l
236
E s ta b lis h e d a g re e m e n ts
(e . g . , C o n s titu tio n
L aw
P a c ts
T re a tie s
T ra d itio n s
In d e p e n d e n t
c o u n c ils a n d
c o m m is s io n s
M e d ia
P e rc e iv e d n e e d s
P o litic a l c o n s tr a in ts ,
a c c id e n ts , p o s s ib ilitie s
D a ta f r o m
o th e r a g e n c ie s
S p e c ia l- in te r e s t
p r e s s u r e g ro u p s
P ro p o s a ls f r o m
o th e r d e p a r tm e n ts
P o lic y
r e v ie w
a g e n c ie s
P o lic y
d e c is io n
p ro ce ss
GOVERNMENT
C o m m itte e
D e b a te
V o te
P o lic y
( L e g is la tio n )
Im p l e m e n ta tio n
P ro p o s a ls
f o r new
le g is la tio n
M IN IS T E R
D e p a rtm e n ta l
d a ta g a th e rin g
D a ta f r o m
o th e r a g e n c ie s
M anagem ent
rocesp d e c i s i o n
A lte r n a tiv e s w ith in le g is la tio n
GOVERNMENT
DEPARTMENT
I n s titu tio n a l
p ro c e d u re
A d m in is tra tiv e
d e c is io n s /
m o n ito rin g
p ro ce ss
D a ta
F ig . 7. 4.
S im p lis tic c o n c e p t of p o lic y , m a n a g e m e n t, a n d a d m in is tr a tiv e
d e c is io n le v e ls in n a tio n a l, r e g io n a l, o r lo c a l g o v e rn m e n t
in a p a r l ia m e n ta r y s y s te m .
237
m o d e ls m a y b e d e s ig n e d a n d u s e d .
M o d els m a y b e d e v e lo p e d to r e l a t e th e
v a lu e of f a r m la n d to th e d is ta n c e f r o m m a r k e ts , to s tu d y i n t e r r e g io n a l
flo w s of c o m m o d itie s , to id e n tify r e g io n s , to d e te r m in e w h ich r e g io n w o u ld
b e n e fit f r o m w h ich ty p e of s u p p o rt u n d e r th e p r o g r a m , an d p e r h a p s e v e n to
s im u la te th e d iffu sio n of know ledge ab o u t th e p r o g r a m to th e f a r m in g
c o m m u n ity s o th a t i t s tim in g an d b u d g e ttin g c a n b e m o r e p r e c i s e .
The
m a n a g e m e n t d e c is io n p r o c e s s w o u ld a lm o s t c e r t a in l y in c o r p o r a te s o m e
s u c h p r o c e d u r e s , b u t w o u ld a ls o r e l y h e a v ily on m e n ta l m o d e ls b a s e d on
th e e x p e rie n c e of th e r e s id e n t g o v e rn m e n t a g r o n o m is ts , th e p r o v in c ia l
m i n i s t e r s of a g r i c u lt u r e a n d t h e i r s ta f f s in v a r i o u s p a r t s o f th e c o u n try ,
a n d th e e x p e rie n c e o f th e d e p a rtm e n ta l a d m in is tr a to r s th e m s e lv e s .
W ith in th e li m it s im p o s e d b y th e le g is la tio n , th e in s titu tio n a l p r o c e d u r e
w o u ld b e d e v e lo p e d a n d p a s s e d to th e a d m in is tr a tiv e u n its f o r im p le m e n ta tio n .
In th e i n i tia l s ta g e s of a d m in is tr a tio n of s u c h p r o g r a m s , d e c is io n s a r e
p r e s c r i b e d a n d h a v e s im p ly to b e im p le m e n te d .
of th e a d m in is tr a tiv e p r o c e s s .
D a ta a r e c o lle c te d a s p a r t
H o w e v e r, a s d if fic u ltie s in im p le m e n ta tio n
a r i s e , a n d a s th e p e o p le in th e f ie ld f in d th a t th e p r o g r a m i s n o t a c c e p te d o r
i s n o t h a v in g th e d e s ir e d r e s u l t s , t h e i r a r g u m e n ts a n d th e s u p p o r tin g d a ta
a r e p a s s e d b a c k to th e m a n a g e m e n t d e c is io n p r o c e s s .
S uch a rg u m e n ts
fr e q u e n t ly in v o lv e lo g ic a l, w e ll-d o c u m e n te d , d a ta -d e p e n d e n t r e p o r t s , b u t in
o u r h y p o th e tic a l e x a m p le th e y w o u ld a lm o s t e n t i r e l y b e b a s e d o n th e m e n ta l
m o d e ls of th e e x p e rie n c e d f ie ld o f f ic e r s .
A t th i s s ta g e th e p r o c e s s e s of m a n a g e m e n t a n d a d m in is tr a tiv e d e c is io n ca n
b e c o n s id e r e d to a c t to g e th e r a s a n it e r a t i v e p r o c e d u r e .
F r e s h d a ta f r o m
a d m in is tr a tiv e s o u r c e s , p e r h a p s a d d itio n a l d a ta f r o m o th e r a g e n c ie s ,
r e p r e s e n t a ti o n s to th e m i n is te r of th e d e p a rtm e n t, an d h is r e d i r e c ti o n of
p r i o r i t i e s o r r e a lig n m e n t of p r o c e d u r a l e m p h a s is a r e s o m e o f th e f a c t o r s
th a t c h a n g e .
P r o g r a m s blo o m , w ith e r , an d d ie in ti m e , a s th e c o n d itio n s in w h ich th e y
o p e r a t e c h a n g e , a s th e n e e d f o r th e m b e c o m e s l e s s r e a l o r a p p a re n t, o r
b e c a u s e th e le g is la tio n o r ig in a lly p a s s e d dow n d o e s n o t allow th e p r o g r a m
to s u c c e e d .
In o u r h y p o th e tic a l c a s e , th e l a s t s itu a tio n m ig h t o c c u r if th e
o r ig i n a l le g is la t io n h a d b e e n f r a m e d to g iv e a i d d ir e c tl y to f a r m e r s o n th e
2 3 .8 ;
m a r g in a l f a r m s o f a c e r t a in r u r a l a r e a , w ithout re c o g n iz in g th a t t h e i r p lig h t
m ig h t b e in e x tr ic a b ly bound t o th e to t a l ec o n o m ic s y s te m in th e r u r a l - u r b a n
r e g i o n th a t in c lu d e d t h e i r a r e a .
I t m ig h t b e c o m e c l e a r a s th e p r o g r a m
p r o c e e d e d th a t th e m a in e ffe c t of th e p o lic y a s im p le m e n te d w as a r a p i d
in c r e a s e in r u r a l - t o - u r b a n m ig r a tio n , an d th a t th e " re h a b ilita te d " , d is p la c e d
m a r g in a l f a r m e r s w e r e b e c o m in g u rb a n w e lfa r e r e c ip ie n ts a n d c r e a tin g a
m o r e s e v e r e s o c ia l an d e c o n o m ic p r o b le m th a n th e one in itia lly fa c e d .
In s u c h c ir c u m s ta n c e s , i t i s c o m m o n f o r a d e p a rtm e n t to p r e p a r e p r o p o s a ls
f o r new le g is la tio n to b e s u b m itte d to g o v e rn m e n t.
T h e se m ay e ith e r a g re e
o r c o n flic t w ith p r o p o s a ls f o r new le g is la tio n f r o m o th e r d e p a r tm e n ts .
A
H e a lth a n d W e lfa re a g e n c y , f o r e x a m p le , m a y h av e id e a s o n th e a p p r o p r i a te
a n s w e r to o u r h y p o th e tic a l p r o b le m c o m p le te ly d iffe re n t f r o m th o s e o f a n
A g r ic u l tu r a l ag e n cy .
m a n y in p u ts .
T h e p o lic y d e c is io n p r o c e s s m u s t b e r e s p o n s iv e to
T h e p r im a r y lin k b e tw e e n th e le v e ls of m a n a g e m e n t d e c is io n
a n d p o lic y d e c is io n i s th e fu n c tio n of th e e le c te d m i n is te r .
H is a w a r e n e s s
o f th e n e e d f o r a ch an g e in p o lic y c o m e s n o t o n ly f r o m th e s e n io r c i v il
s e r v a n t s i n h is ow n d e p a rtm e n t (o r f r o m t h e i r n e g o tia tio n s w ith th e i r c o u n t e r ­
p a r t s in o th e r d e p a rtm e n ts ), b u t f r o m th e a d v ic e o f in d e p e n d e n t c o u n c ils a n d
c o m m is s io n s , f r o m s p e c i a l - i n t e r e s t g ro u p s s u c h a s f a r m e r s ' a s s o c ia tio n s ,
f r o m p e r s o n a l c o n ta c ts , a n d f r o m th e m e d ia .
C o m m is s io n s , su c h a s th e
E c o n o m ic C o u n c il of C a n a d a , m a y w e ll u s e f o r m a l m o d e ls in p r e p a r i n g a
s u b m is s io n (to th e m i n is te r , to p a r lia m e n t, o r f o r g e n e ra l p u b lic a tio n ) o n
th e s t a t e of th e f a r m in g eco n o m y .
T o a l e s s e r e x te n t, a g e n c ie s s u c h a s
f a r m e r s ' a s s o c ia tio n s e m p lo y e c o n o m is ts to h elp th e m p r e p a r e t h e i r a r g u ­
m e n ts .
I t i s p ro b a b le , th o u g h , th a t m o s t s u b m is s io n s a r e b a s e d o n m e n ta l
m o d e ls a n d , in th e c a s e of th e m e d ia , th e y a r e p e r h a p s li m it e d to th e c o n ­
tr i b u tio n of d a ta a n d o p in io n of v a r y in g d e g re e s of r e lia b ility .
T h e p r o c e s s o f p o lic y d e c is io n in g o v e rn m e n t w o rk s in th e m ilie u o f e s t a ­
b li s h e d a g r e e m e n ts ; it o p e r a t e s w ith in th e c o n s titu tio n (w hich m a y h a v e a.
p a r t i c u l a r l y s tr o n g in flu e n c e o n p o lic y u n d e r a f e d e r a l s y s te m ) , t h e la w ,
e x is tin g t r e a t i e s , in te r n a tio n a l t a r i f f a g r e e m e n ts , and tr a d iti o n s o f i n t e r ­
g o v e r n m e n ta l c o n s u lta tio n .
T h e p r o c e s s a ls o w o r k s w ith in p o li tic a l
c o n s tr a in ts , a c c id e n ts , an d p o s s i b ili tie s ;
" p o litic a l" h e r e i s u s e d i n a
239
b r o a d s e n s e t o in c lu d e th e in te r a c tio n s w ith th e b u s in e s s , la b o u r , an d
r e l ig io u s c o m m u n itie s .
d e c is io n s .
T h e s e v a r i a b le s m u s t a l l b e c o n s id e r e d in p o lic y
P o lic y f r e q u e n tly i s in flu e n c e d b y b a c k g ro u n d s tu d ie s , and
p ro p o s e d p o lic ie s a r e o fte n s u b je c t to r e v ie w , b y a g e n c ie s s u c h a s T r e a s u r y
B o a r d , D e p a rtm e n t of F in a n c e , and P r i v y C o u n cil O ffice.
T h e s e a g e n c ie s
m a y o r m a y n o t u s e f o r m a l m o d e ls in t h e i r e v a lu a tio n of p o lic y , b u t a s tr o n g
tr a d iti o n o f e c o n o m ic in p u t/o u tp u t m o d e ls an d n a tio n a l a c c o u n ts (an d to so m e
e x te n t r e g i o n a l a c c o u n ts ) u n d e r l ie s m a jo r f i s c a l d e c is io n s .
H o w e v er, th e
a d v ic e s p e c if ic to a p a r t i c u l a r p o lic y w ill c e rta in ly in c o r p o r a te a s tr o n g
e le m e n t b a s e d on m e n ta l m o d e llin g .
T h e p a r l ia m e n ta r y p r o c e s s of p o lic y d e c is io n b y c o m m itte e d is c u s s io n ,
d e b a te , a n d v o te c o u ld b e d e s c r ib e d a s b e in g b a s e d on m e n ta l m o d e llin g .
It
r e c e i v e s in p u ts of a w id e v a r i e t y of d a ta , s o m e of w h ich m a y c o m e f r o m
g e o g r a p h ic in fo rm a tio n s y s t e m s in th e f o r m of m a p s , d ia g r a m s , s t a t is tic a l
s u m m a r ie s , flow c h a r t s , a n d th e lik e .
F r o m th i s p r o c e s s e m e r g e s (it is
hoped) new p o lic y w h ich , a t n a tio n a l le v e l, m a y b e tr a n s l a t e d in to le g is la tio n .
F r o m th e a b o v e s im p lif ie d d is c u s s io n of th e in te r a c tio n s am o n g d e c is io n ­
m a k in g l e v e ls of g o v e rn m e n t, it i s c l e a r th a t a m ix tu r e o f f o r m a l m o d e ls
a n d m e n ta l m o d e ls i s in v o lv e d in d e c is io n m a k in g .
In g e n e ra l, f o r m a l
m o d e ls p ro b a b ly m a k e t h e i r m a jo r c o n trib u tio n a t th e m a n a g e m e n t le v e l,
a n d a s a n e le m e n t in th e p r o c e s s e s of p o lic y re v ie w (both b a c k g ro u n d rev iew
a n d p ro p o s e d p o lic y re v ie w ).
A ll t h r e e le v e ls of d e c is io n m a k in g , h o w e v e r,
a r e d o m in a te d b y th e u s e of m e n ta l m o d e ls .
D e c is io n s a t th e le v e l of th e
a d m in is tr a tiv e / m o n i to r in g p r o c e s s a r e d ep e n d en t on m e n ta l m o d e ls b e c a u s e ,
to a g r e a t e x te n t, a c tio n s a t th a t le v e l a r e p r e s c r ib e d b y in s titu tio n a l
p r o c e d u r e s (d e c is io n m o d e ls a r e e s s e n ti a ll y p ro v id e d ).
A lthough d a ta
g a th e r in g ( p r o g r a m m o n ito rin g ) i s a fu n d a m e n ta l a c tiv ity a t th is le v e l, few
r e s o u r c e s a r e p ro v id e d f o r a b s tr a c t th o u g h t.
T h e v a lu a b le a d v ic e f r o m th e
a d m in is tr a tiv e le v e l r e l i e s h e a v ily o n th e m e n ta l m o d e llin g p r o c e s s e s of
e x p e rie n c e d a d m i n i s t r a t o r s .
D e c isio n m a k in g a t th e m a n a g e m e n t le v e l, in
c o n t r a s t, h a s th e r e s o u r c e s a n d th e n e e d to u s e f o r m a l m o d e ls ( th e r e is
u s u a lly a " P o lic y a n d P la n n in g " d iv isio n in g o v e rn m e n t d e p a rtm e n ts a t th e
n a tio n a l le v e l in C a n a d a ).
N e v e r th e le s s , th e in p u ts a t th i s le v e l a r e
240
n u m e ro u s an d n o t n e c e s s a r i l y q u a n tifia b le .
T h e ir in te g r a tio n r e l i e s upon
th e e x p e rie n c e (m e n ta l m o d e ls) of th e s e n io r a d m in is tr a to r s an d , in p a r t i ­
c u l a r , on th e in t e r a c t io n b e tw e e n th e d e p a rtm e n t (c iv il s e r v ic e ) a n d th e
m i n is te r ( e le c te d o ffic ia l).
D e s p ite th e in p u t of f o r m a l m o d e ls to th e
p o lic y re v ie w p r o c e s s , p o lic y d e c is io n s m u s t a l s o b e c o n s id e r e d to b e
d e p e n d e n t on m e n ta l m o d e ls .
T h e d e c is io n s a r e b a s e d o n a w id e v a r ie ty
of f a c t o r s , of w h ic h m a n y a r e e s s e n ti a ll y q u a n tita tiv e , s o m e u n c e rta in ,
m a n y d y n a m ic , a n d a l l , to g e th e r , in v a ria b ly c o m p le x .
D e c is io n th e o r y
a n d , in p a r t i c u l a r , th e r e c e n t d e v e lo p m e n t of th e o r y on d e c is io n s u n d e r c o n ­
d itio n s of u n c e r ta in ty a r e not d e v e lo p e d (in 1974) to th e s ta g e w h e r e th e
o v e r a l l p o lic y p r o c e s s of g o v e rn m e n t is a m e n a b le to f o r m a l m o d e ls .
W ith th e a b o v e d is c u s s io n s of th e c h a r a c t e r i s t i c s of f o r m a l s p a ti a l a n a ly s is
a n d an o u tlin e o f th e d e c is io n -m a k in g le v e ls of g o v e rn m e n t in m in d , th e
c o n trib u tio n o f g e o g ra p h ic in fo rm a tio n s y s te m s to th e o v e r a l l s itu a tio n w ill
b e e x a m in e d .
C O N T R IB U T IO N O F D IF F E R E N T T Y P E S O F E X ISTIN G G EO GRA PHIC
IN FO R M A T IO N SY STEM T O FO R M A L S PA T IA L A NALYSIS AND TO
D ECISION MAKING IN GOVERNM ENT
T h e fiv e b r o a d c a te g o r ie s of g e o g ra p h ic in fo rm a tio n s y s t e m s , b a s e d on
d if f e r e n c e s in th e m ix tu r e of t h e i r c h a r a c t e r i s t i c s of m a n ip u la tio n c a p a b ility ,
c a p a b ility to h a n d le v o lu m e s of d a ta , a n d r e s o lu t io n o f lo c a tio n id e n tif ie r ,
w e r e re c o g n iz e d in C h a p te r 6.
T h e y a r e s u m m a r iz e d in th e f iv e ro w s of
F ig u r e 7. 5.
T h e f i r s t c a te g o r y id e n tif ie d i s th a t of s y s t e m s w h o se p r im a r y fu n c tio n is
im a g e h a n d lin g . T h e y a r e not d e s ig n e d to h a n d le c o m p le x s e t s o f d a ta r e l a te d
to th e lo c a tio n id e n tif i e r s , b u t e x is t to p ro d u c e im a g e s , to m a k e th e p r o d u c ­
tio n of m a p s m o r e r a p i d o r m o r e e c o n o m ic a l, o r to f a c i li ta te v is u a l d is p la y .
T h e ir u s e f u ln e s s c a n b e i n f e r r e d f r o m t h e i r e n d p r o d u c ts .
T h o s e w ith a s to r a g e f o r m a t of a r b i t r a r y r e g u l a r a r e a s (T y p e 2), th e SY M A PMIADS g ro u p , a r e u s e d to g e n e ra te in e x p e n s iv e , s im p le , v is u a l e x p r e s s io n s
of s t a t i s t i c s .
T y p ic a l p r o d u c t s 1 a r e g ra p h ic i l lu s tr a t io n s o f in c o m e d e n s ity
in S o u th e rn New E n g la n d ; of d is tr ib u tio n of s e d im e n t c l a s s e s on a p o r tio n of
th e O hio R iv e r flo o d p la in ; of i n d u s tr i a l e m p lo y m e n t a s a p e r c e n ta g e of to t a l
1 . P i c t o r i a l i l lu s tr a t io n s of th e e x a m p le s c i te d a r e c o n ta in e d in W arn tz 1971
a n d T o m lin s o n , R . F . 1972.
G ro u p c h a r a c t e r i s t i c s
T y p ic a l s y s t e m s
P r i m a r y u tility
F a c i lit a te v is u a l d is p la y
P r im a r y u se
M en ta l m o d e ls
P r i m a r i l y im a g e -h a n d lin g s y s t e m s :
F ie ld of a u to m a tic c a rto g ra p h y
V a rie d lo c a tio n id e n tif ie r s
SY M A P, MIADS, e tc .
A UTOM A P
CAN. HYD RO GRA PHIC
R e la tiv e ly h ig h d a ta v o lu m e :
L o w - o rd e r lo c a tio n id e n tif ie r s
an d m a n ip u la tio n c a p a b ility
CENSUS
LU N R, MINN
G e n e r a liz e l a r g e v o lu m e s
of d a ta
M en ta l m o d e ls
F o r m a l m o d e ls u s in g
a g g r e g a te d d a ta
M ed iu m m a n ip u la tio n c a p a b ility :
M ed ium to h ig h d a ta volum e
M e d iu m -o r d e r lo c a tio n id e n tif ie r s
F R IS , GRDSR
D IM E, SACS, O EM
N O RD PLA N
WWW
W id e p o te n tia l a p p lic a tio n
to f o r m a l m o d e ls
P r o v id e e c o n o m ic /r a p id
m a p p ro d u c tio n
INSIGHT
D ev elo p ed b y , a n d r e f l e c t n e e d s
of, c e n s u s o r a d m in is tr a tiv e
a g e n c ie s .
A tte m p t to h a n d le d a ta v o lu m e
w ith g r e a t e r f a c i li ty th a n m a n u a l
te c h n iq u e s o r s y s t e m s u s in g
lo w - le v e l lo c a tio n id e n tif i e r s .
H igh m a n ip u la tio n c a p a b ility :
L im ite d d a ta v o lu m e
M ed ium to h ig h - o r d e r lo c a tio n
id e n tif i e r s
P IO S , NRIS
M A P /M O D E L
GIMMS
F a c i lit a te g r a p h ic t a s k s th a t a r e
p r o h ib itiv e ly ex p e n siv e
b y m a n u a l m e th o d s
M en ta l m o d e ls
S o u rc e of d e r iv e d d a ta f o r
f o r m a l m o d e ls
H ig h - o r d e r lo c a tio n id e n tif i e r :
H igh m a n ip u la tio n c a p a b ility
Low to (p o te n tia lly ) h ig h d a ta
v o lu m e
CGIS
A s ab o v e
N a tio n -w id e d a ta b a s e s tr u c t u r e
M en ta l m o d e ls
S o u rc e o f e x te n s iv e d e riv e d
d a ta f o r f o r m a l m o d e ls
P o te n t ia l a p p lic a tio n to
f o r m a l m o d e ls
241
F ig . 7. 5 C a te g o r ie s o f g e o g ra p h ic in fo rm a tio n s y s t e m s , t h e i r c h a r a c t e r i s t i c s , p r im a r y u tility , an d p r im a r y u s e .
242
e m p lo y m e n t; a n d p e r c e n ta g e s of la n d in r e s id e n tia l u s e (s e p a r a te m a p s ,
s a m e a r e a ) in th e N o r th e a s t e r n C o r r id o r T r a n s p o r ta tio n P r o j e c t , U. S. A . ;
o f a i r p o llu tio n f r o m 2 -h o u r s u lp h u r d io x id e re a d in g s in St. L o u is; o f ch a n g e
in p o p u la tio n b y c e n s u s d i s t r i c t in C an a d a; o r of th e p e r c e n ta g e o f c o c o n u t g ro w in g a c r e a g e s u f f e r in g f r o m b lig h t in M ontegna B ay .
s i m i l a r p r o d u c ts c o u ld b e li s t e d .
M any h u n d r e d s o f
T h e p r o c e s s p r e s e n t s s p a ti a l s t a t i s t i c s
in a f o r m th a t c a n b e m o r e e a s ily c o m p re h e n d e d b y a n o b s e r v e r , a n d i s
u s e d to i l l u s t r a t e r e p o r t s , t o s u p p o rt a v e r b a l p r e s e n ta tio n o f a c o n c e p t o r
p o in t o f v ie w , a n d (o c c a sio n a lly ) to tr i g g e r new u n d e rs ta n d in g o f d i s t r i b u ­
tio n s .
E s s e n ti a ll y th e s y s t e m s p ro v id e in p u t to m e n ta l m o d e ls .
The
A UTO M A P s y s t e m c a n ra p id ly (in 2 h o u rs ) p ro d u c e a s im p le o u tlin e m a p
of a n y p la c e in th e w o r ld , a t a n y s c a l e (f ro m 1 :1 0 ,0 0 0 to 1 :1 ,0 0 0 ,0 0 0 ,0 0 0 )
on a n y o n e of 17 m a p p r o je c tio n s .
P e r ti n e n t d a ta a r e a n n o ta te d b y h a n d on
th e c o m p u te r - p r o d u c e d o u tlin e m a p .
T h e m a p s a r e p ro v id e d b y th e C e n tr a l
In te llig e n c e A g e n c y 1 o f th e U. S. A. a s a b a c k g ro u n d f o r d a ily b r ie f in g s o f
th e D ir e c t o r o f C . I. A. a n d th e P r e s id e n t of th e U n ite d S ta te s .
The
C a n a d ia n H y d ro g r a p h ic S y s te m p ro v id e s a m e a n s of ra p id ly p r o d u c in g
(re v is in g ) h y d r o g r a p h ic c h a r t s f r o m new s o u n d in g s a n d h y d r o lo g ic a l o b s e r ­
v a tio n s .
I t i s ty p i c a l o f s y s t e m s o f " a u to m a tic c a rto g ra p h y " th a t a r e in
e a r l y s ta g e s o f d e v e lo p m e n t in tr a d iti o n a l m a p -m a k in g in s titu tio n s .
T h e o v e r a l l c a p a b ility o f th e s e s y s t e m s i s to r e f o r m a t d a ta f le x ib ly s o th a t
th e y f i t h u m a n m e n ta l u n d e rs ta n d in g of s p a c e , an d in one s e n s e (th a t of
g e n e ra liz a tio n ) t o r e d u c e d a ta v o lu m e.
T h e y a l s o c a n p ro d u c e in n u m e r a b le
g r a p h ic im a g e s , w h ic h m u s t s u b se q u e n tly be v is u a lly e x a m in e d .
of c o u r s e , th e c h a r a c t e r i s t i c s of tr a d iti o n a l c a rto g ra p h y .
T h ese a re ,
In a l l c a s e s , th e
s y s t e m s in th i s c a te g o r y m a k e t h e i r p r im a r y c o n trib u tio n to m e n ta l m o d e ls .
T h e y a r e c o n c e p tu a l e x te n s io n s o f m a n u a l c a r to g r a p h ic p r a c t ic e .
T h e ir
v a lu e l i e s in th e d e g r e e t o w h ich th e y c a n lo w e r th e c o s t o r i n c r e a s e th e
r a p i d ity w ith w h ic h g r a p h ic im a g e s a r e p ro d u c e d .
T h e s e c o n d c a te g o r y c o n ta in s tw o a p p a re n tly d i s s i m i l a r ty p e s o f s y s t e m , th e
tr a d iti o n a l m e th o d of p r o c e s s in g c e n s u s d a ta a n d th e s y s t e m s w ith a s to r a g e
f o r m a t ( la r g e g rid ) o f a r b i t r a r y r e g u l a r a r e a s (T ype 2).
T h e u n d e rly in g
fu n c tio n s , h o w e v e r, a r e th e s a m e : th e y b o th g e n e ra liz e l a r g e v o lu m e s o f d a ta
1. S c h m id t, W. 1973.
243
a n d b o th h a v e a r i s e n f r o m th e n e e d of n a tio n a l o r r e g io n a l g o v e rn m e n ts to
g a th e r s t a t i s t i c s a b o u t t h e i r d o m a in s an d s u b se q u e n tly s u m m a r iz e th e
d a ta f o r h u m a n c o m p re h e n s io n .
T h e v a lu e of s u c h s y s t e m s a t th e a d m in is tr a tiv e le v e l of n a tio n a l, r e g io n a l,
an d lo c a l g o v e rn m e n ts i s m a r g in a l.
B e c a u s e th e y s u m m a r iz e d a ta in to
r e l a ti v e ly l a r g e a r e a l u n its f o r r e a s o n s of co n v e n ie n c e o r c o n fid e n tia lity ,
th e y e ff e c tiv e ly o b s c u r e th e d a ta on w h ich m o s t a d m in is tr a tiv e d e c is io n s a r e
m ade.
T h is i s o n e of th e r e a s o n s w hy a d m in is tr a tiv e le v e ls of g o v e rn m e n t
te n d to g a t h e r t h e i r ow n d a ta .
T h is s itu a tio n is o n ly a m e lio r a te d w h en th e
s u m m a r y a r e a c o in c id e s w ith a n a d m in is tr a tiv e a r e a .
E v e n th i s d o e s n o t
p ro v id e th e d is a g g r e g a te d d a ta r e le v a n t to d e c is io n s a t th e a d m in is tr a tiv e
le v e l.
T h e u s e f u ln e s s of s u c h s y s t e m s to th e m a n a g e m e n t an d p o lic y le v e ls of
d e c is io n m a k in g r e s t s on to t a l c o v e ra g e of th e a r e a th a t th e d e c is io n c o n c e r n s .
T h e v a lu e of s u m m a r ie s of c e n s u s d a ta to n a tio n a l a n d r e g io n a l le v e ls o f
g o v e rn m e n t (w h ile s u b je c t to m a jo r im p ro v e m e n t) is n o t in q u e s tio n .
The
to t a l c o v e ra g e of th e g o v e rn m e n ta l d o m a in i s in h e r e n t in th e c e n s u s p r o c e s s ;
th e p r in c ip a l s u m m a r ie s follow one (u s u a lly p o litic a l) h i e r a r c h i c a l s e t o f
m a jo r a d m in is tr a tiv e a r e a s (though th e r e i s n o th in g " n a tu r a l" ab o u t s u c h
u n its ) .1
If, h o w e v e r, s i m i l a r la r g e - g r id - ty p e c o v e ra te of th e d e c is io n ­
m a k in g a r e a of n a tio n a l o r r e g io n a l g o v e rn m e n ts i s e m p lo y e d , th e a d v a n ta g e o f
r e g u l a r a r e a s i s g a in e d b u t th e m a n u a l p r o c e s s of a s s ig n in g d a ta f r o m o th e r
g r a p h ic f o r m a ts to g r id s q u a r e s i s e n o rm o u s .
T h e r e s u ltin g g r id s q u a r e s
a r e n o t a lig n e d to a d m in is tr a tiv e b o u n d a rie s , th o u g h th e s e m a y b e a p p r o x i­
m a te d i f s o m e f u r t h e r d a ta l o s s i s a c c e p ta b le .
T h e y c a n , h o w e v e r, p r e s e n t
th e g e n e ra liz e d d a t a i n c o m p u te r - g e n e r a te d d is p la y s of th e SYM AP ty p e .
S uch s y s te m s a r e u s e f u l o n ly to f o r m a l s p a ti a l m o d e ls th a t u s e s p a ti a ll y
a g g r e g a te d s t a t i s t i c s .
T h e c e n s u s h a s th e m e r it of m e a s u r in g m a n y a t tr ib u t e s ,
a n d d o e s a t l e a s t p r o v id e a w id e v a r i e ty of s p a ti a ll y a g g re g a te d s t a t i s t i c s .
The
d e s ig n of th e c u r r e n t d a ta b a n k s w ith a la r g e g r id s y s t e m a s s u m e s th a t th e
r e q u i r e d s t a t i s t i c s a r e th e a g g r e g a te d o n e s (but t h e r e h a s b e e n l i t t l e c o n ta c t
to d a te b e tw e e n s y s t e m d e s ig n e r s an d s p a ti a l a n a ly s ts ) , a n d th a t th e s i z e an d
s h a p e of th e a r b i t r a r y u n it of th e s y s t e m a r e a p p r o p r ia te to th e . le v e l o f
1. S e v e r a l d is c u s s io n s h a v e c o n s id e re d th e p ro b le m s in h e r e n t in u s in g d a ta
f r o m a d m in is tr a tiv e u n its th a t a r e n o t s i m i l a r o r c o m p a r a b le w ith r e g a r d to
th e d a ta a g g r e g a te d w ith in th e m . S ee, f o r e x a m p le , H a rv e y 1969, C h a p te r 19,
R o b in so n 1956, T h o m a s , E . N . an d A n d e rs o n 1965, a n d D uncan e t a l. 1961.
244
a g g re g a tio n of th e m o d e l c o n c e rn e d .
F o r a l l ty p e s of s y s t e m in th i s c a te g o ry , o n ly lim ite d o p e r a tio n s of m a n i­
p u la tio n c a n b e c a r r i e d out on th e s u m m a r iz e d d a ta .
T h is is n o t a c o m p u te r
l i m i t a t i o n , b u t i s in h e r e n t in th e n a tu r e o f s u m m a r iz e d d a ta .
G ro u p in g an d
d is p la y a r e s tr a i g h tf o r w a r d , b u t s ig n if ic a n t m e a s u r e m e n ts an d c o m p a r is o n s
c a n b e m a d e w ith in th e d a ta s e t o n ly w hen v e r y l a r g e a r e a s a r e in v o lv ed
(an d th e T y p e 2 s to r a g e f o r m a t i s th e r e b y a p p ro a c h e d ).
P e r h a p s th e r e a l v a lu e of th i s a p p ro a c h to s p a ti a l d a ta h a n d lin g i s th e b a s ic
f a c t th a t i n t e r n a l ly co n s is te n t d a ta s e t s f o r n a tio n a l a n d r e g io n a l a r e a s a r e
a c tu a lly g a th e re d .
T h e f a m i l i a r i t y of c e n s u s s t a t i s t i c s o b s c u r e s th is f a c t,
b u t i t i s m o r e a p p a r e n t in th e r e c e n tly d ev e lo p ed l a r g e g r id s y s t e m s .
The
LU N R 1 s y s t e m of New Y o r k S ta te , f o r e x a m p le , r e q u i r e d a e r i a l p h o to g ra p h y
of th e e n t ir e s ta t e (1 4 0 ,0 0 0 k m 2 ) a n d s ta te - w id e id e n tif ic a tio n a n d c l a s s i f i ­
c a tio n of la n d u s e c a te g o r ie s , r e c r e a t i o n a l f a c i li tie s , tr a n s p o r t a ti o n
f a c i l i t i e s , w a te r r e s o u r c e s , a n d s o f o r th .
q u e n tly s u m m a r iz e d
A lthough th e s e d a ta w e r e s u b s e
in to l a r g e g r id s q u a r e s , th e s ta t e h a s w is e ly m a d e th e
o r ig i n a l d a ta a v a ila b le a s w e ll a s th e s u m m a r y d a ta .2
T h e d e m a n d f o r th e
b a s i c d a ta in g r a p h ic f o r m h a s s o f a r o u ts tr ip p e d th e d e m a n d f o r th e c o m p u te r s to r e d , s u m m a r iz e d d a ta .
T h e g r a p h ic b a s ic d a ta h a s p r i m a r i l y b e e n u s e d
f o r d e c is io n m a k in g a t th e a d m in is tr a tiv e le v e l of g o v e rn m e n t.
T h e " s y s te m "
h a s th u s m a d e m o r e d a ta o b s e r v a tio n s a v a ila b le , ev e n th o u g h it h a s e s s e n
ti a ll y d ep e n d e d on m a n u a l e f f o r t to a c h ie v e th i s .
T h e a u th o r know s o f no
in s ta n c e w h e re th e s u m m a r y d a ta in l a r g e g r id f o r m a t f r o m th a t p a r t ic u l a r
s y s t e m h a s b e e n u s e d in a f o r m a l s p a ti a l m o d el; th e g r id d is p la y s h a v e b e e n
of s o m e v a lu e i n th e m e n ta l m o d e llin g p r o c e s s a t m a n a g e m e n t an d d e c is io n ­
m a k in g le v e ls o f s ta t e g o v e rn m e n t.
T h e t h i r d c a te g o r y c o m p r is e s s y s t e m s th a t a s s ig n d a ta to p o in t lo c a tio n s o r
to lin e s e g m e n ts , a n d a tte m p t to b r in g a d d itio n a l c a p a b ility f o r s p a ti a l m a n i­
p u la tio n to l a r g e v o lu m e s of d a ta .
I t is te m p tin g to s a y th a t no o n e i s m o re
a w a r e of th e m a n ip u la tiv e li m it a ti o n s im p o s e d b y la r g e d a ta v o lu m e s and
lo w - le v e l lo c a tio n id e n tif i e r s th a n th e c e n s u s an d a d m in is tr a tiv e a g e n c ie s
th e m selv e s".
W h e th e r o r n o t th i s is t r u e , th e p r im a r y d e v e lo p m e n t o f th e
l . See C h a p te r 4 , pp. 9 9 - 1 0 3 . 2. R e m e m b e r th a t th e n o n -g ra p h ic s to r e d o es
n o t c o n ta in th e s a m e d a ta s e t a s th e g r a p h ic s to r e . It c o n ta in s a s e le c te d
s e t of m e a s u r e m e n t s , m a n u a lly d e r iv e d f r o m th e g r a p h ic s to r e .
245
G RDSR, D IM E, F R IS , O EM , WWW g ro u p of s y s t e m s h a s b e e n u n d e rta k e n
b y a g e n c ie s r e s p o n s ib le f o r d a ta g a th e r in g r a t h e r th a n im p le m e n ta tio n of
p ro g ra m s.
T h e r e a r e s o m e e x c e p tio n s .
V a rio u s c i tie s in th e U n ite d
K ingdom an d N o rth A m e r ic a (fo r e x a m p le , C o v e n try ,1 O tta w a ,2 and
D e tro it3) h a v e e x p e rim e n te d w ith p o in t-g e o c o d e d p a r c e l f il e s f o r a d m in i
s tra tiv e p u rp o se s.
T h e p ro p o s e d 4 p o in t r e f e r e n c in g s y s t e m in G re a t
B r it a in s te m s f r o m th e in t e r a c t io n of p la n n in g d e p a rtm e n ts a t th e lo c a l
g o v e rn m e n t le v e l a n d th e (now) D e p a rtm e n t of th e E n v iro n m e n t.
The
m e te o r o lo g ic a l s e r v ic e s of v a r io u s c o u n tr ie s p a r t ic i p a tin g in th e WWW
s y s t e m c o lle c t th e d a ta f o r t h e i r ow n a n a ly s is (though th a t p r o b a b ly sh o u ld
n o t b e th o u g h t of a s th e e n d u s e of th e in fo rm a tio n ).
H o w e v e r, th e p a t te r n
i s c l e a r ; th e in itia tiv e h a s b e e n b a s e d on p r a g m a tic c o n s id e r a tio n s r a t h e r
th a n in te lle c tu a l c u r io s ity .
T h e li m ita tio n s o f th i s c a te g o r y of s y s t e m ( in fo rm a tio n r e d u c tio n w ith u s e
o f n o n -o p tim a l lo c a tio n id e n tif i e r s , r e s t r i c t e d in h e r e n t c o n n e c tiv itie s o f
p o in t d a ta s e t s , a n d s o f o rth ) h a v e b e e n d is c u s s e d in th e te x t.5
T h e se
l i m ita tio n s a r e m in im iz e d w h e r e c lo s e ly s p a c e d lo c a tio n id e n tif i e r s a r e
e m p lo y e d .
A c o m m o n u s e of th e s y s t e m s i s to h a n d le u r b a n d ata.
In s p ite of t h e i r li m it a ti o n s , it c a n b e s a id th a t s u c h s y s t e m s allo w a c c e s s to ,
a n d s p a ti a l m a n ip u la tio n o f, d a ta th a t w o u ld o th e rw is e b e u n a v a ila b le ,
b e c a u s e o f th e c o s t o f h a n d lin g h ig h v o lu m e s o r th e s u b m e r g e n c e o f d is a g g r e ­
g a te d d a ta in la r g e a r e a s u m m a r ie s .
T h e y p ro v id e p o te n tia l a c c e s s to m a n y
m e a s u r e d v a r i a b le s in c e n s u s a n d a d m in is tr a tiv e r e c o r d s th a t p r e v io u s ly
c o u ld n o t (in p r a c t ic a l t e r m s ) b e s p a ti a ll y r e l a t e d to one a n o th e r o r ev e n
s p a ti a ll y g ro u p e d to g e th e r .
W ith th e e x c e p tio n of w e a th e r m o n ito r in g (WWW), th e s e s y s t e m s h av e b e e n
d e v e lo p e d a n d te s t e d o n ly s in c e 1968.
A p a r t f r o m WWW, th e r u r a l c a p a b ility
o f G RDSR, a n d th e c o n trib u tio n of INSIGHT (w hich w ill b e d is c u s s e d s e p a r a t e ­
ly b elo w ), th e s y s t e m s h a n d le u r b a n d a ta .
O w ing in p a r t to t h e i r r e c e n t
d e v e lo p m e n t, t h e i r im p le m e n ta tio n a n d u s e in d e c is io n m a k in g h a v e ju s t
b eg u n a n d a r e p o te n tia l r a t h e r th a n a c tu a l.
S e v e ra l e x a m p le s c a n , h o w e v e r,
b e g iv e n to i l l u s t r a t e th e c a p a b ility th a t e x i s t s .
1. C o v e n try C ity C o u n c il 1971. 2. S ym ons 1972b. 3. B e c k e r 1971.
4. D e p a r tm e n t of th e E n v iro n m e n t, U .K . 1973. 5 . See C h a p te r 4 , p p . 9 5 -9 6 .
246
A t th e a d m in is tr a tiv e le v e l of d e c is io n m a k in g , th e p o lic e d e p a rtm e n t in
B o s to n , 1 U. S. A., u s e s i t s D IM E s y s t e m to d is p a tc h e m e r g e n c y c a r s b y
a d d r e s s , in t e r s e c ti o n , a n d s t r e e t lo c a tio n .
an d
P o lic e " in c id e n ts " a r e g eo c o d ed
p o lic e p a t r o l r o u te s a r e r e v i s e d on th e b a s i s of th e d a ta .
L o s A n g ele s2
a n d o th e r c i tie s h av e u s e d c e n s u s d a ta a s s ig n e d to p o in t c o o r d in a te s to
d e v e lo p t e s t s of p o te n tia l c a rp o o l c a n d id a te s on th e b a s i s o f p r o x im ity to
re s id e n c e s , w o rk h o u r s , a n d d is ta n c e to w o rk .
T h e d a ily r o u te m a p s f o r
s o lid - w a s te c o l le c t o r s in B a to n R o u g e, M e m p h is, S h r e v e p o r t, a n d o th e r
c i tie s in th e
U. S. A. a r e r e v i s e d b y u s e o f a lin e s e g m e n t s y s t e m (RAGS)3
s i m i l a r to D IM E; c o lle c tio n c o s ts h a v e b e e n re d u c e d b y 10% to 25%, d a ily
r o u te s h a v e b e e n r e d u c e d f r o m 200 to 175, a n d f r o m 65 to 32, am o n g o th e r
r e s u lts .
S im ila r a p p lic a tio n s in c lu d e a s s ig n m e n t of p u p ils to s c h o o ls ­4 an d
c r e a tio n of s t r e e t m a in te n a n c e a n d r e p a i r s c h e d u le s .5
T h e se p ro c e sse s
p r i m a r i l y r e l y on s p e c if ic d a ta a s in p u t to m e n ta l m o d e ls , b u t o c c a s io n a lly
th e y e m p lo y s im p le p a r t i a l m o d e ls f o r p r o c e s s e s o f n e tw o r k o p tim iz a tio n .
A t th e m a n a g e m e n t le v e l of d e c is io n m a k in g , th e lo c a tio n o f f a c i li tie s r e l a te d
to d is a g g r e g a te d p o p u la tio n c h a r a c t e r i s t i c s i s a ty p i c a l e x a m p le of d e c is io n s
th a t a r e m a d e b e tw e e n a l te r n a t iv e s w ith in a p o lic y .
m a d e on
D e c is io n s h a v e b e e n
lo c a tio n of h o s p ita ls , 6 f a llo u t s h e l t e r s , 7 new s c h o o ls , 8 u n e m p lo y
m e n t o r w e lf a r e o ffic e s ,9 a n d c o m m e r c i a l e s ta b lis h m e n ts ,10
h ig h w ay r o u te s 1
h a v e b e e n e v a lu a te d .
an d a lte r n a tiv e
S im ila r c h o ic e s b e tw e e n a lte r n a tiv e s
h a v e b e e n e x a m in e d in th e e v a lu a tio n of m o d a l c h o ic e 12
b e tw e e n u rb a n
tr a n s p o r t a ti o n n e tw o rk s , g iv e n a p o lic y of in c r e a s in g c o m m u tin g s e r v ic e .
T h e d a ta a r e u s e d in s im p le s p a ti a l m o d e ls in m o s t in s ta n c e s .
A t th e p o lic y le v e l o f d e c is io n m a k in g , d a ta h a v e b e e n c o lle c te d to d is p la y
g ra p h ic a lly th e h ig h
r a t e s of a b a n d o n m e n t of s u b s id iz e d h o u s in g ;13
s t r a t e th e im p a c t of a new r a p i d t r a n s i t
s y s t e m 14
to d e m o n
on p o p u la tio n , la n d u s e ,
an d p u b lic s a f e ty a ro u n d new s ta tio n s ; to d e te r m in e th e p o te n tia l d e m a n d f o r
b a n k s e r v ic e s ;15
p o lic ie s .16
an d to p ro v id e b a c k g ro u n d d a ta f o r s c h o o l d e s e g r e g a tio n
B a s ic a lly , th e d a ta p ro v id e in p u t to m e n ta l m o d e ls .
1. K ra s n a k e v itc h 1973. 2. H o e lz e l 1973. 3. O w en 1972. 4. S a lo m o n ss o n 1973.
5. C ity of V a n c o u v e r 1965. 6. Dowd 1973. 7. T r e ic h e l 1973. 8. B a r r e t t 1973.
9. W e s te r f ie ld 1973. 10. H e a ly 1972. 1 1 . K r a s n a k e v itc h 1973. 12. B a r r e t t
1973. 13. F a r n s w o r t h 1973. 14. B a r r e t t 1973. 15. C ooke 1973.
16. A lm e n d in g e r 1973.
247
D a ta f r o m th i s c a te g o ry o f s y s t e m a r e s u ita b le f o r m a n y ty p e s o f m o r e
c o m p le x f o r m a l s p a ti a l m o d e llin g .
T h e y h a v e b e e n u s e d f o r in p u t to g r a v ity
m o d e ls ,1 f o r e c a s t s of t r i p g e n e ra tio n m o d e ls ,2 f a c i li ty d e m a n d m o d e ls
(the CRA M 3 m o d e l w a s b r ie f ly d e s c r i b e d in C h a p te r 4 , pp.
120 - 121 ).
O th e r s c a n e a s i ly b e e n v isa g e d .
T h e p o te n tia l v a lu e of th i s ty p e o f g e o g ra p h ic in fo rm a tio n s y s t e m f o r u rb a n
d e c is io n m a k in g an d f o r m a l s p a ti a l a n a ly s is i s c l e a r l y h ig h .
N e tw o rk (lin e
s e g m e n t) s y s t e m s p r o b a b ly a r e s o m e w h a t m o re p o te n tia lly u s e fu l th a n p o in t
d a ta s y s t e m s , p r in c ip a l ly b e c a u s e th e c o n n e c tiv ity in h e r e n t in t h e i r f ile
s t r u c t u r e is m o re s p e c if ic .
T h e c o n v e rs io n o f th e p o in t d a ta s y s t e m F R IS
to a lin e s e g m e n t s y s t e m b y N O R D PLA N i l l u s t r a t e s th i s p o in t o f v iew .
T o p o lo g ic a lly r ig o r o u s s y s t e m s w o u ld s e e m s o m e w h a t m o r e u s e f u l th a n
s y s te m s w ith s t r i c t l y m e t r i c co d in g , if o n ly b e c a u s e of th e s tr o n g e r in te r n a l
e d itin g p o s s ib le in th e f o r m e r a n d th e p r a c t i c a l p r o b le m s a s s o c ia te d w ith
d ig itiz a tio n in th e l a t t e r .
I n te r a c tiv e s y s t e m s c a n b e e x p e c te d to a d d a
h ig h e r d im e n s io n of m a n ip u la tio n c a p a b ility , an d of u s e f u ln e s s .
INSIGHT4 (d is c u s s e d in C h a p te r 5,
pp.
175-178) i s ty p ic a l o f a new b r e e d
o f s y s te m , th o s e w ith in t e r a c t iv e c a p a b ility .
I t f a l l s in to th e t h i r d c a te g o r y
b e c a u s e i t c a n p ro v id e a c c e s s to l a r g e d a ta s e t s , h a s a m e d iu m le v e l o f
c a p a b ility f o r s p a ti a l m a n ip u la tio n , a n d ca n u s e m e d iu m - o r d e r lo c a tio n
i d e n tif i e r s ( e s s e n tia lly p o in t d a ta s e t s in IN SIG H T).
A s i m i l a r in te r a c tiv e
s y s t e m o p e r a tin g on lin e s e g m e n t d a ta h a s b e e n d e v e lo p e d 5a s a n a d ju n c t to
SACS b y th e U rb a n D a ta C e n te r in S e a ttle .
T h e a p p lic a tio n o f th i s a p p ro a c h
to th e l a r g e d a ta s e t s a l r e a d y g e o c o d e d (su ch a s GRDSR a n d DIME) w o u ld
ad d a c a p a b ility f o r h e u r i s t i c b r o w s in g an d c o m p a ris o n to a l r e a d y u s e f u l
s y ste m s .
I t w ould a l s o a d d a v a lu a b le new to o l to th e p r o c e s s of m e n ta l
m o d e llin g , w h ic h in t u r n m ig h t o p e n lin e s of in q u iry le a d in g to th e f o r m u l a ­
tio n of h y p o th e s e s th a t c o u ld b e t e s t e d b y n o n in te r a c tiv e u s e o f th e s a m e d a ta
bank.
A g ain , i t c a n b e n o te d th a t th e c a p a b ility w a s d e v e lo p e d in r e s p o n s e
to th e n e e d o f a d a ta g a th e r in g an d a d m in is tr a tiv e a g e n c y of g o v e rn m e n t.
T h e fo u rth c a te g o ry c o n ta in s th e " c o a r s e " poly g o n s y s t e m s (M A P /M O D E L ,
P IO S , N RIS, GIMMS, e t c . ) .
T h e y a r e c h a r a c te r iz e d b y a r e l a ti v e ly h ig h
c a p a c ity f o r m a n ip u la tin g t h e i r s p a ti a l d a ta ; th e y a l l c a r r y o ut o v e r la y w ith
1. W h ite, M. S. 19.73. 2. B a r r e t t 1973.
1972. 5. C a lk in s 1973.
3. F a r n s w o r th 1970. 4 . P h ill ip s , R . L.
248
s o m e d e g r e e of s u c c e s s , a n d c a n m a n ip u la te , c o m p a r e , a n d d e r iv e a v a r i e ty
of s p a ti a l m e a s u r e m e n ts f r o m t h e i r s to r e d d a ta .
" C o a r s e " p o ly g o n s a r e
m e d iu m - to h i g h - o r d e r lo c a tio n id e n tif i e r s , th o u g h , a s y e t, th e s y s te m s
h a n d le low v o lu m e s of d a ta r e l a t e d to th e m .
In e s s e n c e , th e y a r e s u r f a c e -
d e s c r ip tiv e s y s t e m s , d e s ig n e d to f a c i li ta te g ra p h ic t a s k s th a t a r e p r o h ib i­
tiv e ly e x p e n siv e b y m a n u a l m e th o d s .
In th e m a in , t h e i r d e v e lo p m e n t h a s
r e s u lt e d f r o m th e w o rk of g e o g r a p h e r s a n d p la n n e r s , w h o , a s a g ro u p , a r e
p r o f e s s io n a lly in t e r e s t e d in s u r f a c e c h a r a c t e r i s t i c s o f s p e c if ic a r e a s an d
a r e a w a r e of th e e f f o r t in v o lv e d in h a n d lin g g ra p h ic d a ta m a n u a lly .
In t h e i r c u r r e n t s ta t e of d e v e lo p m e n t, none of th e s y s te m s is o f im m e d ia te
b e n e fit to d e c is io n m a k in g a t th e a d m in is tr a tiv e le v e l.
G iv en a s u b s ta n tia l
in c r e a s e in th e a r e a l e x te n t a n d v o lu m e of t h e i r s to r e d d a ta , a n d i n c r e a s e d
e a s e of u s e , th e y c o u ld b e c o m e u s e fu l f o r m o n ito rin g c h a n g e , o r a s a r e a d i ly
u p d a te d d a ta b a s e a g a in s t w h ic h to c h e c k c o m p lia n c e to r e g u la tio n s , s u c h a s
z o n in g d e c is io n s o r b u ild in g p e r m it a p p lic a tio n s .
T h e ir m a in u s e , h o w e v e r,
i s n o t a n tic ip a te d a t th e a d m in is tr a tiv e le v e l.
T h e ir p r im a r y v a lu e l i e s in t h e i r c o n trib u tio n to m a n a g e m e n t an d p o lic y
d e c is io n s .
T h e y ca n c o m p a re (o v e rla y ) tw o o r m o r e a t tr ib u t e s of s u r f a c e -
d e s c r i p tiv e d a ta , s u c h a s p o te n tia l la n d u s e , w ith a c tu a l la n d u s e , f o r e s t
c a te g o r ie s w ith s lo p e c a te g o r ie s , s o il d a ta w ith t r a f f i c z o n e s (PIO S), 1 o r
c o m p a re m a p s of a s in g le a t tr ib u t e p r e p a r e d a t d iff e re n t t i m e s , s u c h a s
la n d u s e of th e s a m e a r e a in 1965 a n d 1970.
T h is p r o c e s s i s a n a la g o u s to
" s ie v e " m a p p in g a n d a llo w s , f o r e x a m p le , s e v e r a l c o n s tr a in ts on la n d
d e v e lo p m e n t to b e c o m b in e d a n d a r e a s s u ita b le f o r d e v e lo p m e n t to b e
p in p o in te d , o r a r e a s w ith m u ltip le s p e c if ie d c h a r a c t e r i s t i c s to b e id e n tifie d
f o r f a c i li ty lo c a tio n .
A v e r y in t e r e s ti n g c a s e of th e a p p ro a c h b e in g u s e d to
d efin e le g a lly an e s ta b lis h e d c o m m u n ity c e n tr e in R o m u lu s, M ich ig an , in
t e r m s of o v e r la p p in g s o c ia l s e r v ic e s a n d a r a n g e of c e n tr a l p la c e fu n c tio n s
w a s r e c e n tly r e p o r t e d b y K o la r s a n d N y stu e n .2
In a l l c a s e s th e s y s t e m s h av e
th e a b ility to p ro d u c e g ra p h ic im a g e s (m ap s) sh o w in g th e r e s u l t s of t h e i r
o p e r a tio n s .
It m u s t b e n o te d th a t m u c h of th e o r ig in a l s u r f a c e - d e s c r ip ti v e
s o u r c e d a ta c o m e s o n ly in th e f o r m of m a p s (o r s i m i l a r g r a p h ic s ) u s in g
i r r e g u l a r p o ly g o n s.
V is u a l c o m p a ris o n b e tw e e n g ra p h ic im a g e s n o t o n ly is
1. S ee d is c u s s io n of P IO S in Ch. 5, pp. 1 4 4-152.
2. K o la r s a n d N y stu e n 1974.
249
ti m e c o n s u m in g , b u t ca n b e m is le a d in g .1
T h e o v e r a l l v a lu e of th is c a te g o r y
o f s y s t e m s l i e s in m a k in g th i s ty p e of d e riv e d d a ta a v a ila b le to th e d e c is io n ­
m a k in g p r o c e s s ; s u c h s y s t e m s ca n in c r e a s e th e n u m b e r of o b s e r v a tio n s th a t
r e l a t e to a d e c is io n .
T h e s y s t e m s c a n d e r iv e q u a n tita tiv e m e a s u r e m e n ts of th e c o r r e la tio n ,
g e n e ra te a g g r e g a te d d a ta w ith in n ew ly d efin ed , i r r e g u la r - s h a p e d a r e a s , an d
d e r i v e q u a n tita tiv e m e a s u r e m e n ts of n u m b e r s o f a t tr ib u t e s , le n g th s o f lin e s ,
a n d e x te n t of a r e a s f r o m t h e i r d a ta b a s e .
T h u s , th e y can in c r e a s e th e
n u m b e r o f d e r iv e d o b s e r v a tio n s th a t a r e e c o n o m ic a lly a v a ila b le f o r in p u t
to f o r m a l s p a ti a l m o d e ls .
(PIO S w a s , in f a c t , s p e c if ic a lly d ev e lo p ed to
p ro v id e d a ta f o r a m o d e l o f u r b a n d e v e lo p m e n t.)
T h e f ifth c a te g o r y i s c h a r a c te r iz e d b y h ig h - o r d e r lo c a tio n id e n tif ie r s (fine
p o ly g o n s ), b u t e q u a lly im p o rta n tly b y h ig h c a p a b ility f o r m a n ip u la tio n a n d
th e p o te n tia l c a p a b ility f o r h a n d lin g la r g e v o lu m e s of d a ta b y a f il e s tr u c t u r e
a l r e a d y d e s ig n e d to a c c o m m o d a te th e m .
A n e s s e n ti a l a s p e c t of th e c a te g o r y
i s th a t a b a s ic f il e s t r u c t u r e f o r s p a ti a l d a ta a llo w s re g io n -w id e o r n a tio n ­
w id e d a ta to b e s to r e d a n d e ffic ie n tly r e t r ie v e d .
T h is im p lie s th a t th e
in h e r e n t p r o b le m s of in t e r n a l tr a n s f o r m a tio n b e tw e e n c o o rd in a te s y s t e m s ,
e d g e m a tc h in g of s o u r c e m a p s h e e ts , d a ta c o m p a c tio n , an d e ffic ie n t f ile
s t r u c t u r e s f o r s p a t i a l d a ta s to r a g e an d r e t r i e v a l h a v e b e e n o v e rc o m e .
At
th e p r e s e n t ti m e (1974), it a ls o im p lie s th a t an e ffic ie n t p r o c e s s o f g ra p h ic
to n o n - g r a p h ic c o n v e r s io n h a s b e e n d e v ise d .
T h e u n d e r ly in g in te n t of s y s t e m s in c a te g o r y 5 is to u s e n o n -g ra p h ic s to r a g e
a s a n a l te r n a t iv e t o g ra p h ic s to r a g e , to s e r v e a s a p e rm a n e n t s o u r c e of
s p a t i a l d a ta o th e r w i s e a v a ila b le o n ly o n m a p s .
I ts o b je c tiv e is to p ro v id e
e c o n o m ic a l a c c e s s to th e s u b s ta n tia l q u a n titie s o f s o u r c e d a ta d e s c r ib in g
a t tr ib u t e s of th e e a r t h 's s u r f a c e r e c o r d e d o n ly on m a p s .
A lth o u g h th is
o b je c tiv e i s a s im p le c o n c e p tu a l e x te n s io n of th e c a p a b ilitie s of s y s te m s
d e s c r i b e d in c a te g o r y 4 , it i s , in m a n y w a y s , p a r a l l e l to th a t o f s y s te m s
lik e GRDSR a n d D IM E ( c a te g o r y 2) th a t n o t o n ly a s s ig n lo c a tio n id e n tif ie r s
to l a r g e d a ta f i l e s , b u t m o r e im p o rta n tly allow c o m p u te r - a id e d s p a tia l
m a n ip u la tio n s to b e p e r f o r m e d on s u c h la r g e d a ta s e t s .
T h e p re v io u s
c o n s tr a in t of s u c h c e n s u s d a ta s e t s w a s th a t no d is a g g re g a te d lo c a tio n
1. E k m a n e t a l. 1963.
250
id e n tif i e r s w e r e a v a ila b le f o r o th e rw is e m a c h in e - r e a d a b le d a ta .
The
p re v io u s c o n s tr a in t of m a p d a ta s o u r c e s w a s th a t t h e i r d is a g g r e g a te d
lo c a tio n id e n tif i e r s w e r e n o t in m a c h in e - r e a d a b le fo r m .
CGIS1 i s a n e x a m p le of a s y s t e m in c a te g o ry 5.
I ts lim ita tio n s a r e n u m e ro u s.
It h a n d le s d a ta o n ly in i r r e g u l a r p o ly g o n f o r m a ts (alth o u g h th e c a p a b ility f o r
h a n d lin g p o in t - r e f e r e n c e d d a ta i s now b e in g ad d e d ).
D e s p ite th e f a c t th a t it
i s d e s ig n e d a s a s t o r e f o r l a r g e a m o u n ts of d a ta , t h e r e is no b ro w s in g
c a p a b ility ; a l l p r o c e s s in g i s done b y b a tc h - p r o c e s s in g .
I ts m a n ip u la tio n
c a p a b ilitie s do n o t in c lu d e h a n d lin g i r r e g u l a r p o ly g o n s th a t d e s c r ib e c o n ­
tin u o u s , s in g le - v a lu e d fu n c tio n s ; th a t i s , it c a n n o t m a n ip u la te o r g e n e ra te
c o n to u rs .
T h e v a lu e of th e ty p e of s y s t e m s in c a te g o ry 5 fo llo w s a s i m i l a r p a t te r n to
c a te g o r y 4 s y s t e m s .
In t h e i r p r e s e n t f o r m th e y c a n m a k e li ttl e c o n trib u tio n
to d e c is io n m a k in g a t th e a d m in is tr a tiv e le v e l, a lth o u g h w ith c o n s id e r a b le
f u r t h e r d e v e lo p m e n t, a n d p a r t i c u l a r l y a n i n t e r a c t iv e m a n /m a c h in e in te r f a c e ,
th e y m ig h t a p p r o a c h th e u s e f u ln e s s of c a te g o r y 3 s y s t e m s f o r d e c is io n m a k in g
a t th a t le v e l.
T h e q u e s tio n c o n c e r n s th e n e e d f o r s u r f a c e - d e s c r ip ti v e d a ta
in s u c h d e c is io n m a k in g r a t h e r th a n th e r e q u i r e m e n t f o r te c h n iq u e s o f s p a tia l
d a ta h a n d lin g .
T h e p r i m a r y v a lu e of c a te g o r y 5 s y s t e m s is a t th e m a n a g e ­
m e n t an d p o lic y -m a k in g le v e ls of d e c is io n m a k in g .
CGIS w a s d e s ig n e d in a g o v e rn m e n t d e p a rtm e n t2 in r e s p o n s e to th e n e e d s of
th a t d e p a rtm e n t to g a th e r an d a n a ly s e d a ta f o r m a n a g e m e n t d e c is io n s .
The
d e p a rtm e n t h a d u n d e rta k e n to ta k e a n in v e n to ry 3 of th e r e s o u r c e s o f th e
p ro d u c tiv e a r e a s of C a n a d a in th e c a te g o r ie s of p r e s e n t la n d u s e , a g r i c u lt u r a l
c a p a b ility , f o r e s t c a p a b ility , r e c r e a ti o n a l s u ita b ility , an d s u ita b ility f o r
w ild life .
E a c h o f th e s e a t tr ib u t e s w a s s e p a r a t e ly o b s e rv e d (as e a c h r e q u i r e d
s e p a r a t e o b s e r v a tio n a l s k ills ) a n d e n c o d e d on s e p a r a t e s e r i e s o f m a p s h e e ts .
A ll d a ta w e r e m a p p e d in th e f o r m of i r r e g u l a r p o ly g o n s.
2 0 ,0 0 0 m a n u s c r ip t m a p s h e e t s w e r e in itia lly in v o lv e d .
B etw e en 1 0 ,0 0 0 an d
T h e d e c is io n s to b e
m a d e b y th e d e p a rtm e n t c o n c e rn e d c h o ic e s a m o n g c o m p e tin g p r o p o s e d la n d
u s e s , b a s e d on c o m p a r is o n of th e v a lu e s of th e v a r io u s la n d a t tr ib u t e s ; th a t
i s , i t w a s n e c e s s a r y to c o m p a re th e a t tr ib u t e s b y o v e r la y o f th e m ap s h e e ts .
A t th i s m a n a g e m e n t le v e l of d e c is io n m a k in g , th e r e te n tio n o f b o u n d a rie s
1. S ee Ch. 5, p p . 152-168 a n d A ppendix. 2. D e p a rtm e n t of F o r e s t r y a n d R u r a l
D e v e lo p m e n t, G o v e rn m e n t of C an a d a. 3. T h e C a n a d a L a n d In v e n to ry .
251
was significant. It was also desired to overlay the data on land attributeswith the boundaries
of census enumeration areas so that the socio-economic attributes of areas could be similarly
examined and correlated. In addition,summaries of widespread correlations between the variables
were neededas a basis for policy decisions. These tasks required high-order (but conceptually
straightforward) manualcartographic
techniques, which were prohibitively expensive in terms ofeffort and time. The contribution
of the CGIS in carrying out these techniques was to provide data to the mental modelling
process at management and policy levels of decision making. Although the system must still be
considered to be experimental, it has provided test data as a basis for mental models at
management and policy levels for comprehensive develop­ ment programs on land use
in Prince Edward Island, Nova Scotia, the Gaspé Peninsula, and Manitoba. The capability
exists within the CGIS to derive measurements and compari­ sons from the stored data and
produce the results in quantitative terms, to assign any result to any point location, or
automatically to assign weightedattribute
values to any size of overlaid grid square (or other arbitrary regular area). It thus has a high
potential as a source of derived data forinput into formal spatial models. The file structure of
the system can accept any descriptor of an attribute and so can respond to as yet unspecified
inputs to formal models that relate to surface attributes within irregular polygons. The
author, however, knows of no instance where data from the system have been used in a formal
spatial model. OVERALL VALUE OF EXISTING GEOGRAPHIC INFORMATION
SYSTEMS In considering the value of geographic information systems, it is worth noting the
difference between a store of information and an informationsystem. Earlier in the thesis1 it
was stated that the usefulness of astore of information depends on whether the type (attributes),
resolutin
(le v e l of d is a g g re g a tio n ), an d f o r m a t (type of lo c a tio n id e n tifie r) o f d a ta
a r e r e l e v a n t to th e d e c is io n s ( a n a ly s is ’) b e in g m a d e , an d a ls o o n th e e a s e
w ith w h ic h th e d a ta in th e s t o r e (in te r m s of t h e i r a t tr ib u t e s , v o lu m e , an d
fo r m a t) c a n b e m a n ip u la te d to p ro d u c e th e in fo rm a tio n on w h ich d e c is io n s
1. Ch. 4 , p. 85.
252
(a n a ly s is ) a r e m a d e .
In view of th e d is c u s s io n s ab o v e , i t s e e m s a p p r o p r ia te
to ad d th a t th e v a lu e of th e s to r e of in fo rm a tio n a ls o d ep e n d s on w h e th e r it s
c o n te n ts a r e p e r c e iv e d to b e n e e d e d f o r e x p la n a tio n o r d e c is io n , th a t is ,
w h e th e r th e tr a in in g of th e u s e r s h a s p ro v id e d th e m w ith f o r m a l o r m e n ta l
to o ls th a t u s e s u c h d a ta .
T h e v a lu e of g e o g ra p h ic in fo rm a tio n s y s t e m s m u s t b e c o n s id e r e d w ith in th is
c o n c e p t Of th e u s e f u ln e s s of s t o r e s of in fo rm a tio n .
It i s c l e a r f r o m th e
d is c u s s io n ab o v e th a t th e c u r r e n t c o n trib u tio n of g e o g ra p h ic in fo rm a tio n
s y s t e m s to b o th f o r m a l a n d m e n ta l ty p e s o f s p a ti a l a n a ly s is is tw ofold:
th e y in c r e a s e th e a m o u n t a n d v a r i e ty of e x is tin g d a ta th a t c a n e c o n o m ic a lly
b e a v a ila b le f o r s p a ti a l a n a ly s is , a n d th e y i n c r e a s e th e c a p a b ility o f m a n i­
p u la tin g th o s e d a ta to p ro d u c e th e in fo rm a tio n a p p r o p r ia te to s p e c if ic ty p e s
of a n a ly s is , th a t i s , w h e re c h a r a c t e r i s t i c s of p la c e a r e in v o lv ed .
It h as
b e e n sh o w n th a t th e s e fu n c tio n s r e s t o n i n c r e a s e s in th e c a p a b ilitie s f o r
re a d in g d a ta , a s s ig n in g th e m to lo c a tio n id e n tif i e r s f o r s u b se q u e n t s p a tia l
a n a ly s is , d e r iv in g d a ta b y m e a s u r e m e n t a n d c o m p a ris o n , a n d g e n e ra tin g
g r a p h ic d is p la y s .
253
C H A P T E R 8 - F U T U R E D E V E L O P M E N T O F G EO GRA PHIC
IN FO RM A TIO N SYSTEM S
D E V E L O P M E N T O F SYSTEM C A P A B IL IT IE S ASSUMING P R E S E N T
C O M P U T E R CH A R A C TE R IST IC S
S e v e ra l u s e f u l li n e s of f u tu re d e v e lo p m e n t c a n f i r s t b e p r o p o s e d w ith in th e
d e l ib e r a t e ly n a r ro w view of th e v a lu e of g e o g ra p h ic in fo r m a tio n s y s te m s
th e m s e lv e s .
A s s u m in g p r e s e n t (1974) c h a r a c t e r i s t i c s , c a p a b ilitie s an d
c o s ts of c o m p u te r s , i t i s p o s s ib le to e n v is a g e d e v e lo p m e n t o f b o th th e
a v a ila b le d a ta b a s e a n d th e m a n ip u la tiv e a b ility u n d e rly in g s p a ti a l a n a ly s is
an d d e c is io n m a k in g .
I m p ro v e m e n ts of th e N o n -g ra p h ic D a ta B a s e
T h e tr e n d in im p ro v e m e n t of te c h n iq u e s f o r tr a n s f o r m a tio n f r o m g ra p h ic to
n o n - g r a p h ic f o r m a t h a s a l r e a d y b e e n n o te d . 1 C e r ta in ly th i s i s a t p r e s e n t
a m a jo r c o n s tr a in t on th e a v a ila b ility of s p a ti a l d a ta th a t c a n b e p r o c e s s e d
b y c o m p u te r .
T h e n a tu r e of th e new te c h n iq u e s in th i s f ie ld h a s a lr e a d y
b e e n e x a m in e d , 1 b u t it m u s t b e r e c o g n iz e d (though i t i s fr e q u e n tly o v erlo o k ed )
th a t th e p r o b le m i s n o t s im p ly one of " d ig itiz a tio n " , b u t r a t h e r of t r a n s ­
fo r m in g a n e r r o r - p r o n e m a n u s c r ip t to a n a c c e p ta b ly e r r o r - f r e e n o n - g r a p h ic
f ile .
T h is en d p ro d u c t is p a r t ic u l a r ly s ig n if ic a n t in th e c u r r e n t s ta g e of
d e v e lo p m e n t of c o m p u te r s th e m s e lv e s , a s th e y a r e n o t s e le c ti v e ly " fo rg iv in g "
in t h e i r s u b s e q u e n t a n a ly s is of d a ta ; th e y m a y b e e ffic ie n t b u t th e y can n o t
in te llig e n tly ig n o r e n o n lo g ic a l e r r o r s .
T h e in t e r a c t iv e c a p a b ility th a t
c o u p le s a m a n 's m in d d ir e c tly to a c o m p u te r, a n d th e s o p h is tic a te d d e v e lo p ­
m e n t of c o m p u te r p r o g r a m s w ith a c a p a b ility f o r m u ltip le , h e u r i s t ic ,
i n t e r n a l e d itin g , a r e s t i l l in a m o s t e le m e n ta l s ta t e .
C o n s e q u e n tly , th e
te c h n iq u e s of p r e - e d i tin g g ra p h ic d a ta f o r d ig itiz a tio n a n d c o r r e c tin g e r r o r s
in th e s u b s e q u e n t f i l e s t r u c t u r e a r e e s s e n ti a l s te p s an d c o s ts in th e p r o c e s s
o f tr a n s f o r m a tio n f r o m g ra p h ic to n o n - g r a p h ic f o r m a t.
Im p r o v e m e n ts in
th e s e a s p e c t s of th e p r o c e s s a r e j u s t a s im p o rta n t a s im p ro v e m e n ts in d ig i­
ti z a t io n , a n d m u s t r e c e iv e m o r e a tte n tio n th a n a t p r e s e n t.
I n c r e a s e s in th e s t o r e of m a c h in e - r e a d a b le d a ta p o te n tia lly a p p lic a b le to a
s p e c ific p r o b le m c a n c o m e f r o m th e e n c o u ra g e m e n t, b y p e r s u a s io n o r l e g i s ­
la tio n , o f c o m p a tib ility b e tw e e n th e a t tr ib u t e s , lo c a tio n id e n tif i e r s , an d tim e
1. C h a p te r 5, p p . 1 7 1 -1 7 5 .
254
id e n tif i e r s of d a ta .
s ta t e d .
T h e c a s e f o r d a ta s ta n d a r d iz a tio n h a s b e e n fre q u e n tly
T h e c a s e f o r n a tio n a l s ta n d a r d s of lo c a tio n id e n tif i e r s h a s b e e n
r e c e n t l y e x a m in e d 1 in th e U. S. A . , an d ev e n th e n a tio n a l s a v in g s o n c o s ts
of s u c h a s te p w e r e e s tim a te d .
U ndoubtedly s u c h lo n g - t e r m o b je c tiv e s
a r e d e s ir a b le , b u t a s a n in t e r im m e a s u r e c o m p a tib ility , r a t h e r th a n
s ta n d a r d iz a tio n , m a y b e m o re r e a d i ly r e a liz e d .
C o m p a tib ility c a n b e
e n c o u ra g e d th ro u g h th e e s ta b lis h m e n t o f g u id e lin e s (a s r e c e n tly a tte m p te d
in th e U. K . ,2 b u t n o t in m a n y o th e r c o u n tr ie s ) , b y th e a d v ic e o f c e n tr a lly
fu n d e d s o u r c e s of e x p e r t is e a v a ila b le a t no c o s t to p a r tic ip a tin g l e v e ls of
g o v e rn m e n t (an a p p r o a c h th a t h a s a p p lic a tio n in a f e d e r a l s y s te m ) , b y
d e s ig n r e q u i r e m e n t s a tta c h e d to th e fu n d in g of p r o g r a m s th a t in v o lv e d a ta
g a th e r in g , an d b y a g r e e m e n t b e tw e e n a g e n c ie s w ith m u tu a lly s u p p o r tiv e
p ro g ra m s.
W ith th e e x c e p tio n of th e l a s t e x a m p le , d a ta c o m p a tib ility a t
th i s le v e l i s c o n s id e r e d to b e a te c h n ic a l is s u e w h ic h c a n b e r e s o lv e d b y
th o s e c o n c e r n e d w ith th e d e s ig n of d a ta h a n d lin g s y s t e m s .
D a ta c o m p a tib ility
d o e s n o t g u a r a n te e th e a v a ila b ility o r e x c h a n g e of in f o rm a tio n , b u t it w o u ld
m a k e p o s s ib le m a n y d e v e lo p m e n ts th a t a r e now im p o s s ib le .
It w o u ld tu r n
th e m a tte r in to one of le g is la tio n a n d n o t of p h y s ic a l f r u s tr a t io n .
I n c r e a s e s in th e s t o r e o f n o n -g ra p h ic s p a ti a l d a ta c a n c o m e f r o m th e d e v e lo p ­
m e n t of te c h n iq u e s th a t a c c e p t n o n -g ra p h ic d a ta d ir e c tl y f r o m q u a n tita tiv e
d a t a g a th e r in g p r o c e s s e s ( s e n s in g , s u rv e y in g , a n d s o fo r th ) .
I t is p a r a d o x ic a l
th a t s u r v e y s f o r m a p p in g p u r p o s e s o fte n g a th e r d a ta f i r s t in n u m e r ic a l fo r m .
T h e s e d a ta a r e th e n tu r n e d in to g r a p h ic d a ta , w h ich m u s t b e tr a n s f o r m e d to
a n o n -g r a p h ic f o r m a g a in f o r c o m p u te r s to r a g e .
a d v a n ta g e s in th e tr a d iti o n a l p r o c e s s .
T h e re a r e , of c o u rs e ,
T h e m o s t s ig n if ic a n t i s h u m a n
i n t e r p r e ta tio n of th e o r ig in a l n u m e r ic a l d a ta to p ro d u c e a g r a p h ic im a g e .
It
i s im p o r ta n t, th o u g h , th a t th e co n c e p t o f s o u r c e s f o r n o n - g r a p h ic s to r a g e is
p u s h e d b a c k b e y o n d th e g ra p h ic im a g e , f o r tw o r e a s o n s .
T h e f i r s t i s th e
f a c t th a t in tr a d iti o n a l " in t e r p r e ta tio n " , n u m e r ic a l s o u r c e d a ta a r e f r e q u e n tly
r e p l a c e d b y g ra p h ic m a te r i a l a s th e o n ly a v a ila b le " s o u r c e " .
C o n to u rs a r e
p r e s e n t e d a s th e s o u r c e d a ta of a S u rfa c e in s te a d of th e m e a s u r e d p o in t
o b s e r v a tio n s on w h ich th e y w e re b a s e d .
D e lin e a tio n s of s o il ty p e s r e p l a c e
th e m a n y q u a n tita tiv e m e a s u r e s o f s o il c h a r a c t e r i s t i c s g a th e r e d w ith c o n ­
s id e r a b le e f f o r t a t e a c h s a m p lin g lo c a tio n .
1. B a r r a c lo u g h 1972.
T h e b a s ic q u a n tita tiv e d a ta a r e
2. D e p a rtm e n t of E n v iro n m e n t, U .K . 1973.
255
e ff e c tiv e ly lo s t , b u t co u ld b e r e t a in e d a n d r e t r i e v e d in c o n c e r t w ith th e
i n t e r p r e t e d im a g e f r o m a d e q u a te n o n -g r a p h ic s to r a g e .
S eco n d ly , s e n s o r s
a r e b e c o m in g a v a ila b le th a t r e c o r d a t tr ib u t e s o f th e e a r t h 's s u r f a c e on ly
in th e f o r m of l a r g e q u a n titie s of n u m e r ic a l c o d e s.
i s a n a d e q u a te e x a m p le of th i s tr e n d .1
T h e E R T S -1 s a te lli te
T h e te c h n iq u e s f o r a c c e p tin g th e s e
d a ta d ir e c tl y in to n o n - g r a p h ic s to r a g e s o th a t th e y c a n b e r e l ia b l y c o m p a re d
w ith o th e r d a ta a r e in an e v e n m o re e m b ry o n ic f o r m th a n s p a ti a l d a ta s y s te m s
th e m s e lv e s .
B u t th e y a r e b e in g d e v e lo p e d , a n d th e f u r t h e r d ev e lo p m en t of
g e o g ra p h ic in f o r m a tio n s y s t e m s to h a n d le s u c h d a ta w ill c e r ta in ly ad d to th e
v o lu m e , c o v e ra g e , a n d ti m e l in e s s w ith w h ic h s p e c if ic a t tr ib u t e s o f e a r t h s u r f a c e d a ta a r e s to r e d f o r u s e .
I m p ro v e m e n ts in M an ip u lativ e C a p a b ility
I n c r e a s e s in th e a b ility of g e o g ra p h ic in f o rm a tio n s y s t e m s to p e r f o r m m a n i­
p u la tio n s c a n s t e m f r o m s e v e r a l li n e s of d e v e lo p m e n t.
b e e n m e n tio n e d in th e te x t.
a c tiv e c a p a b ility .2
T w o o f th e s e h av e
T h e f i r s t i s th e f u r t h e r d e v e lo p m e n t o f i n t e r
T h is is a m o s t s ig n ific a n t a d d itio n , n o t o n ly b e c a u s e it
m a y b e of c o n s id e r a b le b e n e fit to th e e c o n o m ic s of e r r o r c o r r e c tio n , b u t
a l s o b e c a u s e i t a llo w s th e u s e r to " s e e " w h a t i s o th e r w is e a n in v is ib le d a ta
bank.
T h e s in g u la r a d v a n ta g e s of g r a p h ic f o r m s of s to r a g e a r e th e s p e e d of
a c c e s s to d a ta w ith in th e s to r e a n d th e c a p a b ility of b ro w s in g h e u r i s t ic a l ly
th ro u g h a m a p c o lle c tio n .
T h is c a p a b ility i s la c k in g in m o s t c u r r e n t g e o ­
g r a p h ic in fo r m a tio n s y s t e m s , a n d i t i s an im p o r ta n t fa ilin g .
I n te r a c tiv e
s y s t e m s a r e now b e c o m in g f e a s i b le , p r i m a r i l y b e c a u s e of th e ad v e n t of
th e m in i- c o m p u te r a n d lo w - c o s t c a th o d e r a y tu b e d is p la y s (the f o r m e r can
a c t a s a c o m m u n ic a tio n s d e v ic e to a l a r g e r c o m p u te r if a d d itio n a l c a p a c ity
i s c a lle d f o r , a s in th e IN SIG H T3 s y s te m ).
n eed ed fo r su ch s y ste m s.
E ff ic ie n t f il e s t r u c t u r e s a r e
C o n s id e ra b le e f f o r t i s n e e d e d to d ev e lo p i n t e r ­
a c tiv e m a n ip u la tio n c a p a b ility (in a d d itio n to b ro w s in g an d r e t r ie v in g o f d ata).
T h e i n t e r a c t iv e a p p ro a c h , h o w e v e r, i s a n im p o r ta n t k e y to th e u s e f u ln e s s of
n o n - g r a p h ic d a ta s to r a g e f o r th e l a r g e r d a ta s e t s th a t c a n b e ex p e c te d .
T h e s e c o n d lin e of d e v e lo p m e n t in m a n ip u la tio n m e n tio n e d in th e te x t
th a t of m u l ti- f o r m a t s y s te m s f o r h a n d lin g s p a t i a l d a ta .
w as
T h is c a p a b ility h a s
n o t b e e n w id e ly d e v e lo p e d to . d a te , p a r t l y b e c a u s e of th e a t tr a c t iv e s im p lic ity
1. S ee C h a p te r 5 , pp. 1 7 8 -179. 2. See C h a p te r 5, p.1 7 5 . 3. P h ill ip s , R . L . 1972;
s e e a l s o C h a p te r 5, pp. 176-179. 4 . S ee C h a p te r 5, p. 180.
256
o f s in g le - f o r m a t s y s t e m s f o r p r im a r y d e v e lo p m e n t e f f o r ts , an d p a r tly
b e c a u s e of th e la c k o f s p e c if ie d n e e d to r e l a t e d if fe re n t s p a ti a l f o r m a ts in a
m o r e e f fic ie n t s u ite of m a n ip u la tio n s .
U n d o u b ted ly th e a t tr ib u t e s of th e r e a l
w o r ld c a n b e m o r e a c c u r a te ly r e p r e s e n t e d in a n y s to r a g e s y s t e m if s p a tia l
f o r m a t s c a n b e m ix e d .
E q u a lly , it i s c l e a r th a t c e r t a i n f o r m s o f s p a tia l
a n a ly s is c a n b e c a r r i e d out m o re e ffic ie n tly if d a ta a r e a v a ila b le in m a tc h in g
f o r m a ts (m a tc h in g e a c h o th e r a n d m a tc h in g th e te c h n iq u e s e m p lo y e d in th e
s p a t i a l a n a ly s is ) .
T h e p o s s ib le lo s s of in fo rm a tio n in c u r r e d b y ch an g in g
th e f o r m a t m a y not b e s ig n ific a n t to th e p r o b le m b e in g so lv e d .
T h is c a p a ­
b i l i t y i s b e in g e x p lo r e d in v a r io u s s y s t e m s ,1 b u t i f th e r e q u ir e m e n t f o r
m a n ip u la tio n c a n b e s p e c if ie d a d e q u a te ly , it r e p r e s e n t s a f r u it f u l lin e of
d e v e lo p m e n t.
I m p r o v e m e n ts in th e c a p a b ility f o r m a n ip u la tio n ca n a ls o co m e f r o m g r e a t e r
s t a t i s t i c a l u n d e r s ta n d in g of th e m a n ip u la tio n p r o c e s s e s th e m s e lv e s .
a p a r a d o x i c a l s itu a tio n p r e s e n t s its e lf .
A gain,
In th e f i r s t in s ta n c e , m a n y p o te n ­
t i a l l y u s e fu l p r o c e d u r e s of m a n ip u la tio n , w h ic h s y s t e m s a r e a lr e a d y in h e r e n tly
c a p a b le of p e r f o r m in g , a r e n o t a tte m p te d .2
In th e s e c o n d in s ta n c e , m a n ip u la ­
tio n s a r e c a r r i e d o u t a n d th e r e s u l t s a r e a c c e p te d w ith o u t th e a s s u m p tio n s
u n d e rly in g th e o p e r a tio n s b e in g e x a m in e d .
M o st o f th e s y s t e m s in c a te g o r y 4 o r 5 g iv e n in C h a p te r 7 (pp. 247-252) h a v e
th e c a p a b ility f o r o v e r l a y (p atch on p a tc h ).
c o m p a r is o n c a n b e g e n e ra te d .
M e a s u r e s of a s s o c ia tio n of th e
It i s dou b ted , h o w e v e r, w h e th e r th e in h e r e n t
p o s s i b ili ty of p r o d u c in g s p u r io u s r e s u l t s h a s b e e n e x a m in e d b y s y s te m
d e s ig n e r s .
T h e r e is e v e n l e s s e v id e n c e of th e d e s ig n of m a n ip u la tio n
f u n c tio n s th a t c o u ld in v e s tig a te s u c h c o m p a r is o n s , f o r in s ta n c e , b y c r o s s c o r r e l a t i o n b e tw e e n v a r i o u s s c a l e s o b ta in e d b y s p e c t r a l a n a ly s is , th o u g h th is
w o u ld b e a f a i r l y s tr a i g h tf o r w a r d p r o c e d u r e to im p le m e n t ev e n w ith th e
e x is tin g f il e s t r u c t u r e s .
C le a r ly , s t a t i s t i c a l m e th o d s m u s t b e in te g r a te d
1. C h a p te r 5, pp. 1 8 3 -1 8 4 . 2. T h e r e a s o n f o r n o t c a r r y i n g o u t m a n ip u la tio n s
th a t s y s t e m s c a n p e r f o r m is c o m p lex . P a r t l y it i s la c k of a s p e c if ie d n e e d ,
p a r t l y i t i s th e in a b ility o f n o n - u s e r d e s ig n e r s of s y s t e m s to r e c o g n iz e th e
c a p a b ili tie s o f t h e i r s y s t e m , p a r t ly it i s th e f e a r a tta c h e d to a n y s t a t e - o f - t h e a r t p r o je c t a n d e x p r e s s e d b y th e a ttitu d e " L e t w e ll enough a l o n e ," a n d p a r t ly
i t i s la c k o f r e s o u r c e s ("T h e d e s ig n e r s a r e h a v in g a h a r d en o u g h tim e m a k in g
th e s y s t e m w o rk a s i t i s , w ith o u t w a n tin g f u r t h e r ta s k s t h r u s t upon th e m " )
E s s e n ti a ll y , it i s a r e f l e c ti o n of th e e a r l y s ta t e of d e v e lo p m e n t of th e s y s te m s .
257
w ith th e c a p a b ility f o r m a n ip u la tio n in s y s t e m d e s ig n if s e n s ib le u s e i s to
b e m a d e of e x is tin g a n d f u tu r e g e o g ra p h ic in fo r m a tio n s y s te m s .
T h e im p o r ta n c e of th i s lin e of d e v e lo p m e n t i s e m p h a s iz e d b y a n e x a m p le ,
q u o te d b y D a n g e rm o n d ,1 of th e s e c o n d in s ta n c e : w h e re a m a n ip u la tio n i s
c o m m o n ly c a r r i e d o u t w ith o u t e x a m in a tio n o f th e a s s u m p tio n s u n d e rly in g
th e o p e r a tio n .
T h e c a s e i s th e s im p le one of a r e a l o v e rla y ( in te r s e c tio n of
s e ts ) w h e r e it i s a s s u m e d th a t th e p o ly g o n s b e in g o v e rla id a r e h o m o g e n eo u s
w ith in th e m s e lv e s .
T h e C o m m o n w e alth S c ie n tific a n d I n d u s tr ia l R e s e a r c h
O r g a n iz a tio n (CSIRO) in A u s t r a li a m a n u a lly o v e r la id t h r e e s e t s of p o ly g o n s
a n d c a r r i e d o u t f ie ld c h e c k s to d e te rm in e w h e th e r th e a t tr ib u t e s th a t
c o in c id e d a t s p e c if ic p o in ts on th e m a p s a c tu a lly c o in c id e d in th e fie ld .
O nly in 38% of th e c a s e s c o u ld th e y c o r r e c t l y p r e d i c t th e p r e s e n c e of th e
t h r e e a t t r i b u t e s to g e th e r on th e g ro u n d .
T h is is o la te d r e s u l t m a y b e due to
a v a r i e t y of f a c t o r s , in c lu d in g th e p o s s ib ility of in a c c u r a te o r ig in a l s u r v e y .2
I t d o e s , h o w e v e r , i l l u s t r a t e th e la c k of u n d e rs ta n d in g of e v e n s tr a ig h tf o r w a r d
p r o c e s s e s of s p a ti a l m a n ip u la tio n w h ich a r e r e g u l a r l y c a r r i e d o u t.
p r o b le m e x te n d s to th e u s e of s ta n d a r d s t a t i s t i c a l p r o c e d u r e s .
The
A co m m o n
a s s u m p tio n in s t a t i s t i c s i s th a t v a r i a b le s a r e in d e p e n d e n t, h e n c e th e d iffic u lty
of a p p ly in g th e m to tim e s e r i e s o r s p a ti a l d a ta .
T h e p ro b le m s of a u t o c o r r e la
tio n h a v e , of c o u r s e , b e e n r e c o g n iz e d ,3 b u t th e f a c t r e m a in s th a t v e r y few
s ta n d a r d s t a t i s t i c a l p r o c e d u r e s a r e a s p a tia l.
In g e n e r a l, s t a t i s t i c i a n s h a v e n o t d e v e lo p e d te c h n iq u e s th a t a r e r e a d i ly
a p p lie d to s p a ti a l p r e d ic tio n .
T h e r e a r e e x c e p tio n s .
W e in e r4 in 1930
in tr o d u c e d w o rk on g e n e r a l h a rm o n ic a n a ly s is , a n d M a th e ro n 5 b u ilt on th is
w o r k a n d in tro d u c e d a new fie ld o f s t a t i s t i c s , d if f e re n t f r o m th e tr a d iti o n a l
o n e in th a t it a s s u m e s th a t v a r i a b le s a r e r e l a t e d to e a c h o th e r .
Som e
g e o g r a p h e r s 6 a r e s t a r t i n g to a p p ly th e s e a p p ro a c h e s to s p a ti a l a n a ly s is , b u t
s u c h s o p h is tic a tio n i s n o t co m m o n .
M o re f r e q u e n tly , a n a tte m p t is m a d e
to c o n v e rt s p a ti a l d a ta to a f o r m th a t f i t s th e u n d e rly in g a s s u m p tio n s , o r e v e n
to p r o c e e d w ith o u t u n d e rs ta n d in g th e a s s u m p tio n s .
Such m a n ip u la tio n s m a y
a c q u ir e e v e n m o r e s p u r io u s v a lid ity w hen th e y a r e th e r e s u l t of a s u p p o se d ly
a c c u r a te c o m p u te r p r o c e d u r e .
Im p ro v e m e n t of c a p a b ilitie s f o r m a n ip u la tio n
m u s t r e s t o n a b e t t e r u n d e rs ta n d in g of th e s t a t i s t i c a l b a s i s o f th e o p e ra tio n s
1. D a n g e rm o n d 1973. 2. W hich a r g u e s s tr o n g ly f o r th e d e v e lo p m e n t of in d ic e s
of th e r e l i a b i l i t y of s o u r c e d a ta an d t h e i r in c o r p o r a tio n a s f la g s in n o n ­
g r a p h ic s to r a g e . 3. C liff a n d O rd 1973. 4. W e in e r 1930, 1958. 5. M a th e ro n
1970. 6. S w itz e r, P . 1973, R a y n e r 1974, f o r e x a m p le .
258
in v o lv ed .
A v it a l lin e of d e v e lo p m e n t, r e l a te d to th e p ro b le m s m e n tio n e d ab o v e b u t
c o n s id e ra b ly m o re fu n d a m e n ta l in n a t u r e , i s in v e s tig a tio n of th e lo g ic a l
p r o p e r t i e s of th e la n g u a g e s a v a ila b le f o r o r d e r i n g s p a tia lly d is tr ib u te d d a ta .
C u r r e n tly , tw o d if fe re n t ty p e s of la n g u a g e a r e u s e d f o r id e n tify in g g e o g r a ­
p h ic a l in d iv id u a ls .
O ne la n g u a g e ty p e is u s e d to d e s c r ib e th e a t tr ib u t e s ,
an d th e o th e r th e s p a c e - t im e p r o p e r t ie s , o f th e in d iv id u a l (the " s u b s ta n c e
la n g u a g e " an d th e " s p a c e - t im e la n g u a g e " r e f e r r e d to b y W ils o n 1).
N o tio n s
o f g e o g r a p h ic a l s i m i l a r i t y of in d iv id u a ls th u s m a k e it im p e r a tiv e to d e s c r i b e
s a m e n e s s in a t l e a s t tw o la n g u a g e s .
T o d e riv e in d iv id u a ls s p e c if ie d in one
la n g u a g e (s a y th e s p a c e - t im e la n g u ag e) f r o m in d iv id u a ls s p e c if ie d in th e
o th e r la n g u a g e , a n a d e q u a te tr a n s l a ti o n p r o c e s s i s r e q u ir e d .
H a rv e y 2
s u g g e s ts th a t th e m ix in g of s u c h la n g u a g e s u n d e r l ie s th e d iffic u lty s u r r o u n d in g
re g io n a l c o n c e p ts in g e o g ra p h ic th o u g h t.
T h e e x te n s io n o f g e o g r a p h ic a l
p r o b le m s in to fo u r - d im e n s io n a l s p a c e (a v e r y s im p le co n cep t) im m e d ia te ly
i l l u s t r a t e s th e lim ita tio n s an d a w k w ard s t r u c t u r e s r e s u lt in g f r o m th e u s e of
c u r r e n t la n g u a g e s .
A n e x a m p le , p ro v id e d b y F lo w e rd e w ,3 w o u ld b e th e
d e s c r ip tio n in a s u b s ta n c e la n g u a g e of th e d is tr ib u tio n in a c o u n tr y o f th e
" w o rk in g c l a s s " ; s u c h d e s c r ip tio n s ca n n o t b e e f f ic ie n tly h a n d le d in e x is tin g
g e o g ra p h ic in fo rm a tio n s y s te m s .
A lth o u g h i t w o u ld b e v a lu a b le , i t i s n o t
p o s s ib le in th i s th e s i s to re v ie w o r in i tia te d is c u s s io n on g e o g ra p h ic c o n c e p ts
o f s p a c e , th e ch a r a c t e r i s t i c s of e x is tin g la n g u a g e s , a n d th e n e e d e d ty p e s of
d e v e lo p m e n t.
I m p o rta n t r e c e n t c o n trib u tio n s to o th e r th a n e x is tin g la n g u a g e s
h a v e b e e n m a d e: b y Hä g e r s tr a n d 4 a n d G rig g 5 c o n c e r n in g th e c o n c e p t o f th e
" g e o g ra p h ic a l in d iv id u a l" ; b y T o b le r 6 w ho e x te n d s th e e v e ry d a y c o n c e p t o f
g e o g ra p h ic a l s p a c e b e y o n d th e s ta n d a r d E u c lid e a n fra m e w o r k ; a n d b y D acey ,7
F lo w e rd e w , 8 an d B e ta k 9 in t h e ir in v e s tig a tio n s of th e c o n c e p ts an d f u r t h e r
d e v e lo p m e n t of s p a ti a l la n g u a g e .
D e s p ite th e s e e x a m p le s , g e o g r a p h e r s
h a v e done li ttl e w o rk in th is c r i t i c a l f ie ld .
C le a r ly , th e f a c i li ty w ith w h ich
o n e c a n d e s c r ib e th e s p a ti a l in te r a c tio n of s u r f a c e a t tr ib u t e s d e p e n d s on th e
la n g u a g e u s e d f o r th e d e s c r ip tio n .
T h e d e s ig n o f f i l e s t r u c t u r e s f o r g e o g r a ­
p h ic in fo rm a tio n s y s t e m s a ls o d ep e n d s on th a t la n g u a g e .
T h e e f fic ie n t d e s ig n
of g e o g ra p h ic in fo rm a tio n s y s te m s , a n d in p a r t i c u l a r t h e i r p r o v is io n o f d a ta
1. W ils o n , N . L . 1955. 2. H a rv e y 1969, C h. 14, p. 216. 3. F lo w e rd e w 1974.
4 . H a g e r s tr a n d 1953, 1963, 1967b. 5. G rig g 1965, 1967. 6 . T o b le r 1963, 1964b,
1970, T o b le r e t a l. 1968. 7. D acey 1964, 1965a, 1965b. 8 F lo w e rd e w 1973a,
1973b. 9. B e ta k 1974a, 1974b.
.
259
f o r d y n a m ic s p a ti a l m o d e ls , m u s t d e p e n d on in c r e a s e d c o n trib u tio n s f r o m th i s
lin e of d e v e lo p m e n t.
IM P A C T O F C O M P U T E R D E V E L O P M E N T ON G EO GRA PHIC
IN FO R M A T IO N SYSTEM S
T h e a b o v e d is c u s s io n of lin e s of d e v e lo p m e n t w e r e b a s e d on p r e s e n t - d a y
c h a r a c t e r i s t i c s , c a p a b ilitie s a n d c o s ts of c o m p u te r s . T h e d e v e lo p m e n t of
c o m p u te r c a p a b ilitie s , h o w e v e r, c o n tin u e s a p a c e a n d it is p o s s ib le to
s p e c u la te b r ie f ly o n t h e i r im p a c t on g e o g ra p h ic in f o rm a tio n s y s t e m s .
W ith o u t f u r t h e r ju s ti f ic a tio n , it w ill b e a s s u m e d th a t c o m p u te r s to r a g e c a p a ­
c i tie s w ill in c r e a s e ; a c c e s s ti m e s w ill d e c r e a s e ; th e c o s t p e r b it o f in f o r m a ­
tio n p r o c e s s e d w ill d e c r e a s e ; h ig h e r - o r d e r (m o r e h u m a n - o r ie n te d ) c o m p u te r
la n g u a g e s w ill b e d e v e lo p e d th a t allow e a s y u s e of c o m p u te r s b y p e o p le w ho
a r e n o t p r o g r a m m e r s ; in te r a c tiv e p e r i p h e r a l d e v ic e s an d s u p p o r tin g s o ft
w a r e w ill p r o li f e r a te ; th e c a p a c ity of lo w - c o s t m in i- c o m p u te r s w ill in c r e a s e ;
c o m m u n ic a tio n n e tw o r k s b e tw e e n c o m p u te r s w ill in c r e a s e ; th e w o rld -w id e
a v a ila b ility of c o m p u te r s w ill in c r e a s e ; a n d th e n u m b e r of p e o p le a b le to u s e
c o m p u te r s w ill in c r e a s e .
T h e r e is s u ffic ie n t e v id e n c e in r e a d i ly o b s e r v a b le
t r e n d s to b e s u r e th a t th e s e d e v e lo p m e n ts w ill o c c u r.
O th e r s 1 ca n b e f o r e ­
s e e n , b u t a r e n o t r e q u i r e d f o r th e p r e d ic tio n s l i s t e d below .
T h e fo llo w in g d e v e lo p m e n ts r e l a te d to g e o g r a p h ic in fo rm a tio n s y s t e m s c a n
b e e x p e c te d :
T h e t r e n d to w a r d c r e a tio n of la r g e f il e s o f n o n - g r a p h ic , s p a tia lly c o d e d d a ta
w ill c o n tin u e an d p ro b a b ly a c c e le r a te .
T h e 1970-71 C e n s u s o f U. S. A . a n d
C a n a d a i s a v a ila b le to th e p u b lic in th e f o r m o f m a c h in e - r e a d a b le s u m m a r ie s
o f s p a ti a ll y c o d e d s m a l l a r e a s .
E v e r y tow n a n d c i ty in F r a n c e w ith a p o p u la ­
tio n of m o r e th a n 20, 000 i s s c h e d u le d to h a v e a n u r b a n d a ta s y s t e m o f th e
l i n e - s e g m e n t (DIME) ty p e b y 1975.
T h e O rd n a n c e S u rv e y o f G r e a t B r it a in
h a s a d o p te d n o n - g r a p h ic s to r a g e f o r i t s m a s t e r m a p s h e e ts o f to p o g ra p h ic
su rv ey .
A ll h y d r o lo g ic a l d a t a g a th e re d b y th e E n v ir o n m e n ta l P r o te c tio n
A g en cy in U. S. A. ( c u r r e n t ly 10 y e a r s o f o b s e r v a tio n s , u s in g 700 x 106 b y te s
of s to r a g e ) is now in n o n - g ra p h ic f o r m .
M any f u r t h e r e x a m p le s c o u ld b e
p ro v id e d .
1. S o m ew h at m o re e s o t e r i c d e v e lo p m e n ts m ig h t in c lu d e m a jo r c h a n g e s in
c o m p u te r a r c h i te c tu r e s u c h a s th e d e v e lo p m e n t o f l a r g e - s c a l e p a r a l l e l .
c o m p u te r s (su c h a s IL L IA C IV ), s p e c i a l- p u r p o s e c o m p u te r la n g u a g e s (e. g . ,
f o r s p a t i a l a n a ly s is ) , a w id e r a n g e of g r a p h ic d a ta in p u t/o u tp u t d e v ic e s ,
o p tic a l m e m o r ie s , h o lo g ra p h ic m e m o r ie s , a n d th e d e v e lo p m e n t o f th e a b ility
t o p r o c e s s n o n -c o d e d in fo rm a tio n .
260
T h e u s e of m in i- c o m p u te r s a n d in t e r a c t iv e d is p la y s f o r h a n d lin g s p a ti a l d a ta
w ill r a p i d ly i n c r e a s e , b o th f o r te a c h in g te c h n iq u e s a n d f o r o p e r a tio n a l g e o g r a ­
p h ic in fo rm a tio n s y s t e m s .
F o r e x a m p le , i t i s q u ite p r a c t ic a l, e v e n now
(1974), to s t o r e m a p s on m a g n e tic ta p e in in e x p e n s iv e ($ 3 .0 0 ), s ta n d a r d
(P h illip s ) c a s s e t t e s , f o r u s e w ith m i n i- c o m p u te r s .
Im p ro v e d c o m m u n ic a tio n n e tw o rk s b e tw e e n m a jo r c o m p u te r s w ill allow
c o m p a tib le d a ta s o u r c e s to b e c o r r e l a te d .
P i c t u r e p r o c e s s in g w ill b e c o m e e c o n o m ic a l a n d w ill g r e a t ly a d d to th e s t o r e
o f s p a ti a ll y c o d e d d a ta on a t tr ib u t e s of th e e a r t h 's s u r f a c e in n o n - g r a p h ic
fo rm .
M u ltid im e n s io n a l f il e s t r u c t u r e s w ill b e d e s ig n e d , w h ich m a y e n c o u ra g e
i n t e r d is c i p lin a r y g a th e r in g of b io s p h e r ic d a ta a n d th e d e v e lo p m e n t of m o r e
c o m p le x , d y n a m ic m o d e ls .
F u r t h e r s p e c u la tiv e c o m m e n ts c o u ld b e a d d e d w ith l i t t l e d iffic u lty .
H o w e v e r,
e v e n w ith th i s m o d e s t l i s t i t c a n b e s u g g e s te d th a t th e e n v ir o n m e n ta l,
e c o n o m ic , an d s o c ia l n e e d s of s o c ie ty w ill e n c o u ra g e u s e of th e l a r g e f il e s
o f n o n - g r a p h ic d a ta b e in g c r e a te d , a n d th a t g e o g r a p h e r s w ill ta k e ad v a n ta g e
o f th e r e l a t e d d e v e lo p m e n ts in th e te c h n o lo g y o f d a ta h a n d lin g f o r th e d e s ig n
of g e o g ra p h ic in fo rm a tio n s y s te m s .
D E V E L O P M E N T O F G EO G RA PH IC IN FO R M A T IO N SY STE M S IN
CO N T EX T O F T H E O V E R A L L V A LU E O F S TO R ES O F S PA T IA L
IN FO R M A T IO N
It w a s n o te d a b o v e th a t th e v a lu e of g e o g ra p h ic in fo rm a tio n s y s t e m s f it s
w ith in th e c o n c e p t of th e u s e f u ln e s s of s t o r e s of s p a t i a l in fo rm a tio n .
It w as
s u g g e s te d th a t th e p e r c e iv e d n e e d f o r d a ta a n d t h e i r r e le v a n c e w e r e im p o r ta n t
e l e m e n ts in th e w id e r c o n c e p t of u s e f u ln e s s .
I t w o u ld p e r h a p s s e e m
r e a s o n a b l e f i r s t to p e r c e iv e th a t d a ta a r e r e q u i r e d , th e n to d e c id e u p o n th e
r e l e v a n t a t tr ib u t e s a n d f o r m a ts , a n d t h e r e a f t e r to d e s ig n and im p le m e n t th e
te c h n iq u e s to h a n d le th e m .
In th i s p r a g m a ti c w o rld , h o w e v e r, i t i s n ot
u n c o m m o n f o r th i s lo g ic a l s e q u e n c e to b e d is tu rb e d .
T e c h n iq u e s f o r
h a n d lin g d a ta h a v e p ro b a b ly b e e n d e v is e d th a t s t i l l a w a it th e p r o v is io n of
" r e l e v a n t" d a ta , an d th e y m a y w a it s t i l l lo n g e r b e f o r e th e v a lu e o f th o s e d a ta
i s p e r c e iv e d .
I t is e q u a lly p ro b a b le th a t d a ta a r e g a th e r e d w ith o u t an y
261
e x is tin g te c h n iq u e s f o r t h e i r h a n d lin g , o r an y p e r c e iv e d n e e d f o r th e m .
The
c o m m e n ts in th e a b o v e s e c tio n of th i s c h a p te r c o n c e rn in g th e f u tu r e d e v e lo p ­
m e n t of g e o g ra p h ic in fo rm a tio n s y s te m s h a v e f o c u s s e d m o r e o n th e n a r r o w
c o n c e p t of t h e i r v a lu e .
T h e w id e r co n c e p t an d s o m e of th e c o m p le x itie s
in th e r e l a ti o n s h i p s b e tw e e n g e o g ra p h ic in fo r m a tio n s y s t e m s , f o r m a l s p a tia l
a n a ly s is , a n d d e c is io n m a k in g in g o v e rn m e n t w ill b e c o v e re d in th e fo llo w in g
p a r t of th i s c h a p te r .
T h e c o n c e p tu a l d ia g r a m o r ig in a lly p r e s e n te d in C h a p te r 7 (F ig . 7. 1) is u s e fu l
in il lu s tr a t in g s o m e of th e s e c o m p le x itie s ( s e e F ig . 8. 1 b elow ).
FORM AL
S P A T IA L
A NALYSIS
S p a tia l
th e o r y
G EO G R A PH IC
IN FO R M A TIO N
SYSTEM S
F a c t s in fluG
Pe n c e d b y
K
-A
IS
C
D
T
M
N
R
E
V
O
a p r i o r i th e o r ie s /h y p o th e s e s
S to r e s o f s p a tia l
in fo rm a tio n
T h e o r ie s te s t e d
a g a in s t f a c ts
F ig . 8. 1.
dck,fy
plextsnhrabw
om
ig.81C
F
C o m p le x itie s in th e r e la tio n s h ip s b e tw e e n d e c is io n m a k in g ,
g e o g r a p h ic in fo rm a tio n s y s te m s , a
262
p ro v id e s a m e a s u r e a g a in s t w h ich e x c e p tio n a l a n d u n iv e r s a l e v e n ts a r e
re c o g n iz e d .
In a w o rld w ith o u t th e o r y t h e r e a r e no e x c e p tio n s ; e v e ry th in g
i s u n i q u e . "B u r to n 1 a ls o p o in te d o u t th a t " th e m o m e n t a g e o g r a p h e r b e g in s
to d e s c r i b e a n a r e a , h o w e v e r, h e b e c o m e s s e le c tiv e (fo r it is n o t p o s s ib le
to d e s c r i b e e v e ry th in g ) a n d in th e v e r y a c t of s e le c tio n d e m o n s tr a te s a
c o n s c io u s o r u n c o n s c io u s th e o r y o r h y p o th e s is c o n c e rn in g w h at i s s ig n if i­
c a n t." S im ila r ly , th e g a t h e r e r s o f d a ta a n d p r o v id e r s of s t o r e s o f in f o rm a tio n
a r e s e le c ti v e ( fo r it i s n o t p o s s ib le to d e s c r i b e e v e ry th in g ) an d in th e v e r y
a c t o f d a ta s e le c ti o n u s e a c o n s c io u s o r s u b c o n s c io u s th e o r y O r h y p o th e sis
c o n c e r n in g w h a t i s s ig n if ic a n t an d " r e l e v a n t" .
In d e s ig n in g in fo rm a tio n
s y s t e m s , to o , th e d e s ig n e r s c h o o s e b e tw e e n c r e a tin g d iffe re n t f il e s t r u c t u r e s
a n d m a n ip u la tio n f a c i li tie s on th e b a s is of t h e i r c o n s c io u s o r s u b c o n s c io u s
th e o r y o r h y p o th e s is c o n c e rn in g w h a t is s ig n if ic a n t.
I t h a s a l r e a d y b e e n m e n tio n e d th a t t h e r e h a s b e e n l i ttl e c o n ta c t b e tw e e n th o s e
c o n c e rn e d w ith f o r m a l s p a ti a l a n a ly s is an d th o s e c o n c e rn e d w ith th e d e v e lo p ­
m e n t o f g e o g r a p h ic in fo rm a tio n s y s t e m s .
In n u m e ro u s c a s e s , a s h a s b e e n
sh o w n , th e s y s t e m s h a v e b e e n d e v e lo p e d b y g o v e rn m e n t d a ta g a th e r in g an d
a d m in is tr a tiv e a g e n c ie s th a t r e l y e x te n s iv e ly on m e n ta l m o d e ls .
T h is c r e a te s
no d if f ic u ltie s p e r s e , b u t th e r e l a tio n s h ip b e tw e e n s u c h d a ta a n d f o r m a l
s p a ti a l a n a ly s is i s no lo n g e r n e c e s s a r i l y th e r e l a ti v e ly s tr a ig h tf o r w a r d one
o f la rg e- s t o r e s o f f a c t s b e in g o rg a n iz e d in to th e o r y , a s th e d a ta a r e on ly
a v a ila b le i n p r e f a b r i c a t e d b u n d le s .
In a d d itio n , if th e s to r e s o f s p a tia l
in f o r m a tio n a r e a s s u m e d to r e p r e s e n t th e to t a l d a ta a v a ila b le an d to c o n ta in
th o s e f a c t s a g a in s t w h ic h th e o r ie s m u s t a ls o b e te s t e d , t h e r e i s th e e v e r ­
p r e s e n t p o s s i b ili ty of c i r c u l a r a rg u m e n t u n le s s th e to t a l d a ta s e t i s s u ita b ly
p a r t iti o n e d .
L e s s o b v io u s i s th e d a n g e r th a t e a c h s id e in s u c h a p a r t iti o n h a s
b e e n in flu e n c e d b y th e c o n s c io u s o r s u b c o n s c io u s a p r i o r i th e o r ie s o r h y p o
th e s e s o f d a t a g a t h e r e r s a n d d e s ig n e r s of g e o g ra p h ic in fo rm a tio n s y s te m s .
T h e s itu a tio n i s f u r t h e r c o m p lic a te d b y th e o v e r a l l r e la tio n s h ip b e tw e e n s to r e s
of in f o rm a tio n a n d d e c is io n m a k in g in g o v e rn m e n t.
F o llo w in g th e ab o v e a r g u ­
m e n t, i t co u ld b e s u g g e s te d th a t g o v e r n m e n ta l d e c is io n m a k in g , p a r t ic u l a r ly
at: m a n a g e m e n t a n d p o lic y le v e ls (to th e e x te n t th a t th e y r e l y o n g o v e rn m e n t
s o u r c e s of d a ta ) , is in flu e n c e d b y th e su p p ly of d a ta th a t r e s id e s in th e s to r e s
1. B u r to n 1963, p . 156.
263
o f in fo rm a tio n .
I t ca n b e a rg u e d , o n th e o th e r h a n d , th a t th e su p p ly of d a ta
u s e d in th e d e c is io n - m a k in g p r o c e s s i s c o n s id e ra b ly in flu e n c e d b y th e a im s
a n d o b je c tiv e s of th e a g e n c ie s of g o v e rn m e n t re s p o n s ib le f o r d e c is io n s .
D e s p ite a tr a d iti o n a l s e p a r a t io n of d a ta g a th e rin g a g e n c ie s (su ch a s c e n s u s
an d s u rv e y ) f r o m lin e g o v e rn m e n t d e p a r tm e n ts , m a n y d a ta a r e g a th e r e d ,
a n d a r e g e n e r a lly u n d e r th e c o n tro l of (and o fte n c o n fid e n tia l to ) , th e l a t t e r
ty p e of a g e n c y .1
Such d a ta a r e fr e q u e n tly in c o m p a tib le in tim e , u n it, an d
s p a ti a l c h a r a c te r f r o m o n e in s titu tio n to a n o th e r .
T h e s e le c tio n o f c o n te n ts
of m a n y s t o r e s of in f o rm a tio n co u ld , in th i s s e n s e , b e c o n s id e r e d to b e
c o n tr o lle d b y s u c h in s titu tio n s .
T h e o v e r a l l su p p ly of d a ta i s th u s p a r titio n e d
in to s u b s e ts w h ich a r e b ia s e d b y th e th e o r i e s and h y p o th e se s th a t u n d e r lie
d e p a r tm e n ta l a c tio n s .
P o lic y an d p r o g r a m s te n d to b e e x p la in e d in t e r m s of
s u c h d a ta s u b s e ts , an d e v e n tu a l le g is la t io n te n d s to b e im p le m e n te d w ith in
th e in d iv id u a l ju r i s d i c ti o n s of th e s a m e in s titu tio n a l f ra m e w o r k .
T h e re a re
c h e c k s a n d b a la n c e s in th e s y s te m , a s h a v e b e e n n o te d (fo r e x a m p le , th e
p o lic y re v ie w a g e n c ie s an d th e p r o c e s s of p a r l ia m e n ta r y g o v e rn m e n t its e lf ) ,
b u t, to q u o te F o x 1 in a r e c e n t C a n a d ia n p u b lic a tio n of th e (fe d e ra l) D e p a rtm e n t
o f S upply a n d S e r v ic e s , B u r e a u of M a n a g e m e n t, "T h e p r o c e d u r e s o f
r e p r e s e n t a ti v e g o v e rn m e n t c a n e a s i ly b e c o m e u n d e m o c r a tic , w ith M e m b e rs
o f P a r li a m e n t an d th e g e n e r a l p u b lic th e v ic tim s of th e g o a ls a n d b ia s e s o f
th e s p e c i a li s t s (and in s titu tio n s ) w ho c o n tro l th e g e n e ra tio n of in fo rm a tio n
o n w h ic h d e c is io n s m u s t b e b a s e d ." C le a r ly , th e r e la tio n s h ip b e tw e e n
a v a ila b le d a ta , s p a ti a l a n a ly s is , a n d g o v e rn m e n t d e c is io n i s n o t s t r a i g h t ­
fo r w a r d .
F U T U R E D E V E L O P M E N T S W ITH IN T H E D ISC IP L IN E O F G EOGRAPHY
S om e of th e c o m p le x itie s in h e r e n t in th e o v e r a l l r e la tio n s h ip s h a v e b e e n
b r ie f ly m e n tio n e d .
T h is le a d s t o a r e - e x a m in a tio n of th e lin k a g e b e tw e e n
f o r m a l s p a ti a l a n a ly s is a n d g e o g ra p h ic in fo r m a tio n s y s t e m s , a n d c o n s id e r a ­
tio n of t h e i r f u tu r e in te r a c tio n .
T h e s e c o n c e r n s m ig h t b e c o n s id e r e d to
f a l l w ith in th e d is c ip lin e of g e o g ra p h y it s e lf , a s il l u s t r a t e d in th e n e x t c o n c e p
tu a l d ia g r a m (F ig . 8. 2).
O ne a s p e c t of th i s b r o a d f ie ld of s tu d y , th e
1. F o x 1973. 2. O th e r ty p i c a l e x a m p le s a r e : th e in te r a c tio n b e tw e e n g e o g ra p h ic
in fo rm a tio n s y s t e m s an d q u a n tita tiv e te c h n iq u e s n e e d e d to m e a s u r e o r d e r iv e
m e a s u r e s f o r e n v iro n m e n ta l in ta n g ib le s (fo r a re v ie w of th e l a t t e r te c h n iq u e s
s e e C o o m b e r an d B is w a s 1972), a n d th e in te r a c tio n of f u r th e r th e o r e ti c a l
a n a ly s is o f th e te m p o r a l d im e n s io n p e r s e a n d th e r e s u lt a n t r e s tr u c t u r in g o f
s p a c e - t im e m o d e ls le a d in g to a r e d e s i g n of g e o g ra p h ic in fo rm a tio n s y s te m s
(s e e , f o r e x a m p le , th e d is c u s s io n of te m p o r a l d im e n s io n s b y I s a r d 1970).
264
b e t t e r u s e of a p r i o r i k n o w led g e a n d th e a t tr ib u t e - s p a c e - t im e in te r a c tio n s
am o n g d a ta , w ill b e u s e d a s an e x a m p le .
D ECISION - MAKING
PROCESS
FORM A L
S P A T IA L
ANALYSIS
G EO G RA PH IC
IN FO R M A T IO N
SYSTEM S
F u tu r e d e v e lo p m e n t w ith in d is c ip lin e
• D e v e lo p m e n t of GIS a s a b a s i s f o r s p a ti a l a n a ly s is
• I n te g r a te d d a ta h a n d lin g an d m o d e l- b u ild in g p r o c e s s
• S p a tia l a n a ly s is u s e d t o d e te rm in e p a r a m e t e r s o f GIS
F ig . 8. 2.
F u tu r e d e v e lo p m e n ts w ith in th e d is c ip lin e of g e o g ra p h y .
W hile i t m a y b e o b s c u re (a s p o in te d o u t ab o v e ), it i s r e a l l y n o t s u r p r is in g
th a t a p r i o r i kn o w led g e in flu e n c e s th e c o n te n ts of s t o r e s o f in fo rm a tio n .
A lthough i t b ia s e s a v a ila b le s t o r e s , th e a p p ro a c h i s n e c e s s a r y a n d u n d e r ­
s ta n d a b le .
In f a c t, in d is c u s s in g th e r e la tio n s h ip s b e tw e e n f o r m a l s p a tia l
a n a ly s is a n d s t o r e s of in fo r m a tio n (and in p a r t ic u l a r th e c o n te n ts an d c a p a ­
b i l i t i e s of g e o g ra p h ic in fo rm a tio n s y s te m s ) , it is o f c e n t r a l c o n c e rn .
J a m e s T o b in ,1 q u o te d b y K o o p m a n s, p u ts th e u n d e rly in g is s u e c l e a r ly b y
s a y in g th a t q u a n tita tiv e m e th o d s " a n d d e v e lo p m e n ts in h ig h - s p e e d c a lc u la tin g
m a c h in e s m a k e it p o s s ib le to w o rk w ith (econom ic) m o d e ls o f m u c h g r e a t e r
c o m p le x ity , s c o p e an d d e ta il th a n w a s f o r m e r l y th o u g h t p o s s ib le .
W hat is
w ro n g is th e p o o r q u a lity o f th e p ie c e s th a t w e p u t to g e th e r in s u c h m o d e ls ."
I t w a s a rg u e d in th e p re v io u s c h a p te r 2 th a t th e c o n trib u tio n m a d e b y g e o g r a ­
p h ic in f o rm a tio n s y s t e m s w a s to in c r e a s e th e a m o u n t a n d v a r i e ty o f e x is tin g
s p a ti a l d a ta , a n d i n c r e a s e th e c a p a b ility f o r m a n ip u la tin g th o s e d a ta .
The
q u e s tio n s t i l l to b e a n s w e r e d i s w h e th e r th e s e d e v e lo p m e n ts c a n a f fe c t th e
" q u a lity of th e p ie c e s " th a t a r e p u t to g e th e r.
1. T ob in 1953.
2. Ch apter 7, p. 252.
265
K o o p m an s,1 in h is e x a m in a tio n of tw o e c o n o m ic m o d e ls , n o te d th a t " th e y h a d
n o t sh o w n th e e x is te n c e of a d e fin ite p a y -o ff to f u r t h e r d is a g g r e g a tio n .. . th e y
d id n o t show a n in c r e a s e in f le x ib ility c o m m e n s u r a te w ith t h e i r g r a d u a l
in c r e a s e in s iz e a n d in d e ta il.
T h is w a s p a r t i c u l a r l y tr u e f o r th e in p u t-o u tp u t
m o d e l, in w h ich a s im p le th e o r e ti c a l s c h e m e w as im p r e s s e d on a l a r g e r an d
l a r g e r b o d y of d e f e n s e le s s d a ta ."
A rg u m e n ts s i m i l a r to th e s e co u ld b e p r e s e n t e d c o n c e rn in g f o r m a l s p a tia l
a n a ly s is .
D e s p ite th e c u r r e n t a c tiv ity in m o d e l b u ild in g a n d te s t in g , th e r e
s e e m s to b e a n u n d e r c u r r e n t of d is s a ti s f a c ti o n w ith t h e i r o u tc o m e , and
c e r t a in l y m o d e ls a r e n o t w id e ly a p p lie d to d e c i s i o n m a k in g .
A lth o u g h c o m ­
p u tin g c a p a b ilitie s an d th e p o te n tia l c o n trib u tio n of g e o g ra p h ic in f o rm a tio n
s y s t e m s h a v e d e fin ite ly m a d e it p o s s ib le to in c o r p o r a te m o r e in f o r m a tio n in
m o d e ls , th e p e rc e p tio n of how to ta k e a d v a n ta g e of th e s e c a p a b ilitie s is
la c k in g . I t is c l e a r th a t a m e r e in c r e a s e in th e a m o u n t of d a ta u s e d d o e s n o t
g u a r a n te e in c r e a s e d u n d e rs ta n d in g of s p a tia l d is tr ib u tio n a n d in te r a c tio n s .
K o o p m a n s 1 s u g g e s ts th a t b e t t e r u s e m u s t b e m a d e of a p r i o r i k n o w led g e , b u t
in a k e y p h r a s e p o in ts o u t th a t " s u c h a p r i o r i k now ledge th a t w e h a v e a p p lie s
to in d iv id u a l s itu a tio n s ".
H e a r g u e s th a t a h ig h d e g re e of d a ta d is a g g r e g a tio n
i s n e e d e d to e m p lo y s u c h k n ow ledge, a n d a t th e s a m e tim e a g r e a t e r f le x i­
b i l i t y in a s s u m p tio n s i s n e c e s s a r y t o m a k e th e le v e l of d is a g g r e g a tio n m e a n in g ­
fu l.
H e o b s e r v e s th a t th e d e g r e e of d is a g g r e g a tio n i n m o d e ls m a y n o t b e
s u f f ic ie n t to p e r m it th e u s e of a g r e a t d e a l o f a v a ila b le in f o r m a tio n an d th a t,
in m o s t c ir c u m s ta n c e s , e s ti m a t e s of b e h a v io u r p a r a m e t e r s o b ta in e d f r o m
a g g r e g a te d a ta do n o t h a v e th e d i r e c t a n d e x c lu s iv e r e la tio n s h ip to th e d e s ir e d
in d iv id u a l b e h a v io u r p a r a m e t e r s . " T h u s , th e d e g re e of a g g r e g a tio n u s e d d o es
n o t p e r m i t u s to e x p lo it th e s im p l e s t ty p e s of a p r i o r i in f o r m a tio n w e p o s s e s s ."
T h e s e l a t t e r th o u g h ts h av e b e e n m o re r e c e n tly c o n f ir m e d b y w o r k e r s c o n c e rn e d
w ith s p a ti a l m o d e ls , an d h av e b e e n p a r t ic u l a r ly e v id e n t in p ro b le m s c o n c e rn in g
h u m a n b e h a v io u r.
I s a r d a n d R e i n e r 2 p o in te d out th a t
"m o d e ls o f h u m a n b e h a v ­
i o u r o v e r s p a c e h a v e b e e n a lm o s t e n t ir e l y o r ie n te d to m a s s p r o b a b ilis tic
b e h a v io u r." O n th e b a s is of e x te n s iv e e x p e rie n c e w ith m ig r a tio n an d d iffu sio n
m o d e ls , H ä g e r s tr a n d 3 n o te d th a t
in s p ite of th e in tu itiv e fe e lin g am o n g a ll
w o r k e r s in th e fie ld (of m ig ra tio n ) th a t m ic r o - e n v ir o n m e n ta l f a c t o r s a r e
1. K o o p m an s 1957.
2. I s a r d a n d R e i n e r 1966.
3. Hä g e r s tr a n d 1970.
266
im p o r ta n t in th e d e c is io n to m o v e , n e a r l y a ll m o d e ls in v o lv e o n ly t h e e x t r a ­
p o la tio n of c u r r e n t a g g re g a te b e h a v io u r."
U n til now , h o w e v e r, i t h a s g e n e ra lly b e e n a s s u m e d th a t m ic r o d a ta h av e
th e in h e r e n t p r o b le m of b e in g c r e a te d b y a c tiv ity w ith in th e d a ily r a n g e of
th e m a jo r it y of th e p o p u la tio n , a n d h e n c e a r e s u b je c t to a v a r i a b il ity th a t
i s a v o id e d in th e h o m o g e n e ity o f m a c ro d a ta .
N e v e rth e le s s , lin k a g e s m u s t
b e d e v e lo p e d b e tw e e n s u c h m ic r o d a ta an d th e a g g re g a te d a ta if w e a r e to
g a in a n u n d e rs ta n d in g of th e l a r g e s o c io -e n v iro n m e n ta l m e c h a n is m s th a t
a g g r e g a te d a ta f a i l to g iv e u s .
O ne av e n u e of a p p ro a c h to th is p r o b le m ,
s u g g e s te d b y H ä g e r s tr a n d ,1 i s th e p h y s ic a l a p p ro a c h in v o lv in g th e s tu d y o f
how e v e n ts o c c u r in th e t i m e - s p a c e fra m e w o rk .
T h is im p lie s t h e a v a ila b ility
o f g e o g ra p h ic in fo rm a tio n s y s t e m s w h o se f ile s t r u c t u r e s and la n g u a g e s a r e
c o n s id e r a b ly f u r t h e r d e v e lo p e d th a n th o s e d e s c r ib e d in th is th e s i s ; i t
e m p h a s iz e s th e e a r l y s ta g e of d e v e lo p m e n t of e x is tin g te c h n iq u e s .
F r o m th e s e th o u g h ts , h o w e v e r, it i s p o s s ib le to s u m m a r iz e s o m e p o s s ib le
fu tu r e li n e s of d e v e lo p m e n t th a t in v o lv e in te r a c tio n s b e tw e e n f o r m a l s p a t i a l
a n a ly s is a n d g e o g ra p h ic in fo r m a tio n s y s te m s .
1) B e t t e r u s e of th e a p r i o r i k now ledge of in d iv id u a l s itu a tio n s in v o lv e s th e
u s e of d is a g g r e g a te d d a ta s e t s , a n d im p lie s th e th e o r e ti c a l d e v e lo p m e n t
o f lin k a g e s b e tw e e n m ic r o d a ta an d m a c r o d a ta , s o th a t u n d e rs ta n d in g of
th e l a r g e r s o c io - e n v ir o n m e n ta l m e c h a n is m s ca n b e gain ed .
2) T h e s e d e v e lo p m e n ts in tu r n r e s t on a d v a n c e s in g e o g ra p h ic in f o r m a tio n
s y s t e m s , b o th to m a k e b e t t e r u s e of a v a ila b le s t o r e s of in fo rm a tio n a n d
t o h a n d le th e a t t r i b u t e - s p a c e - t i m e in te r a c tio n s am o n g d a ta .
T h i s in t u r n
w ill d e p e n d on s u b s t a n ti a l im p r o v e m e n ts in th e file s tr u c t u r e s o f g e o g r a ­
p h ic in fo r m a tio n s y s t e m s .
A s d e m o n s tr a te d in C h a p te rs 4 a n d 5, th e
c u r r e n t f il e s t r u c t u r e s a r e a t b e s t s tr a ig h tf o r w a r d an d a r e th e p r o d u c t
o f s y s t e m d e s ig n e r s ' c a p a b ilitie s r a t h e r th a n u s e r d e m a n d s .
3) T h e d e v e lo p m e n t of m o r e e f fic ie n t f il e s t r u c t u r e s w ill d e p e n d to a
c o n s id e r a b le e x te n t on th e th e o r e ti c a l d ev e lo p m en t of m u ltid im e n s io n a l
la n g u a g e s .
T h is ty p e of m u tu a l d e v e lo p m e n t of f o r m a l s p a ti a l a n a ly s is a n d g e o g ra p h ic
in fo r m a tio n s y s t e m s w ill h a v e c o n s id e ra b le im p a c t on th e e c o n o m ic
1. Hä g e r s tr a n d 1970.
267
a v a ila b i lit y of a d d itio n a l r e le v a n t in f o rm a tio n f o r th e u n d e rs ta n d in g of
s p a t i a l d is tr ib u tio n a n d in t e r a c t io n s .
T h e s p e c if ic a p p ro a c h e s w ith in th e s e
i n t e r a c t in g li n e s of d e v e lo p m e n t m u s t n e c e s s a r i l y r e l y on f u tu r e w o rk .
T h e o r e tic a l d e v e lo p m e n t a lo n g th e s e li n e s , h o w e v e r, a s s u m e s a c c e s s to
d a ta .
S uch a c c e s s i s p o s s ib le in c o u n trie s w ith tr a d iti o n s of o p e n c e n tr a l
r e g i s t e r s of m ic r o d a ta , s u c h a s Sw eden.
P e o p le w o rk in g in o th e r c o u n tr ie s
m ig h t h a v e to c a r r y out r e s e a r c h w ith in th e a e g is of in s titu tio n s th a t g a th e r
s u c h d a ta , th o u g h i t c a n b e n o te d th a t g e o g ra p h ic a l in fo r m a tio n s y s t e m s to
d a te h a v e l a r g e l y b e e n b u ilt b y s u c h a g e n c ie s .
T h e c o n s tr a in ts o n w id e r
u s e of d a ta im p o s e d b y s o c ia l a n d in s titu tio n a l c o n fid e n tia lity w a s d is c u s s e d
e a r l i e r 1 in th e th e s i s a n d c a n p r e s e n t f o r m id a b le o b s ta c le s to in v e s tig a tio n .
S o m ew h at m o r e p r a g m a ti c b u t c o n s id e r a b ly m o r e c o m p le x a r e th e lin k a g e s
b e tw e e n g o v e r n m e n ta l d e c is io n m a k in g a n d th e te c h n iq u e s o f s p a ti a l d a ta
h a n d lin g a n d a n a ly s is .
T h e a r e a of c o n c e rn i s il l u s t r a t e d in th e c o n c e p tu a l
d ia g r a m (F ig . 8. 3) b elo w .
Som e of th e p o s s ib le t r e n d s in d e c is io n m a k in g
in r e s p o n s e to d e v e lo p m e n ts in g e o g ra p h ic in fo r m a tio n s y s te m s a n d s p a ti a l
a n a ly s is a r e sh o w n , an d w ill b e d is c u s s e d in th e te x t th a t fo llo w s.
F U T U R E D E V E L O P M E N T S R E L A T E D T O D ECISION MAKING IN
GO V ERN M EN T
DEC ISIO N - MAKING
PR O C E SS
5 • C h an g e s in in s titu tio n a l s t r u c t u r e s to allow in te llig e n t
n e g o tia tio n of p r o b le m - s o lv in g a p p r o a c h e s in t e r m s of
a v a ila b le to o ls an d d a ta su p p ly ( tr a d in g - p o s t co n cep t)
3 • P o s t - u n i v e r s i t y te c h n o lo g y
t r a n s f e r to d e c is io n m a k e r s
2 • B e t te r d e s ig n of f o r m a l
m o d e ls an d t h e i r i n c o r ­
p o r a tio n in d e c is io n ­
m a k in g p r o c e s s
FORM AL
S P A T IA L
ANALYSIS
F ig . 8. 3.
4 • I n c r e a s e d f e e d b a c k to d a ta
g a th e r in g a g e n c ie s
1 • D ev elo p m en t o f i n t e r ­
a g e n c y d a ta lin k a g e
G EO GRA PHIC
IN FO R M A TIO N
SYSTEM S
F u tu r e d e v e lo p m e n ts of d e c is io n m a k in g in r e s p o n s e to d e v e lo p ­
m e n ts in g e o g ra p h ic in fo rm a tio n s y s t e m s an d s p a tia l a n a ly s is .
1. Ch. 2, p p . 5 5 -56.
268
T w o in t e r r e l a t e d d e v e lo p m e n ts a ffe c tin g d e c is io n -m a k in g in s titu tio n s u n d e rly
th e n e e d to im p ro v e d e c is io n m a k in g in g o v e rn m e n t.
F i r s t , a s th e i n t e r ­
d e p e n d e n c e of th e p e o p le o f a n a tio n in c r e a s e s , a u th o r ity an d r e s p o n s ib ility
f o r g o v e rn m e n ta l a f f a i r s a p p e a r to g r a v ita te u p w a rd f r o m lo c a l to r e g io n a l
to n a tio n a l g o v e rn m e n t.1
fo r re v e rs a l.
T h is tr e n d i s s tro n g , th o u g h n o t w ith o u t p r e s s u r e s
I n c r e a s i n g le v e ls of e d u c a tio n , p o p u la tio n , c o m m u n ic a tio n ,
a n d s ta n d a r d of liv in g , c o u p le d w ith th e a p p a re n tly in c r e a s in g " r e m o te n e s s "
o f g o v e rn m e n t, h a v e f o s t e r e d d e m a n d s f o r g r e a t e r c itiz e n p a r tic ip a tio n
in th e d e c is io n s b e in g m a d e b y g o v e rn m e n t (as in itia lly d is tin c t f r o m th e
o v e rth ro w of g o v e rn m e n t).
In s o m e c a s e s th is p r e s s u r e , in c o n c e r t w ith
o th e r s , h a s le d to w a rd m o v e m e n ts f o r d ev o lu tio n .
N e v e r th e le s s , th e im p a c t
o f g o v e rn m e n t d e c is io n s on p r iv a te liv e s in c r e a s e s .
S eco n d ly , th e d e c is io n s th a t f a c e g o v e rn m e n ts a r e ra p id ly b e c o m in g m o re
c o m p le x , a s c l e a r l y d e m o n s tr a te d b y th e c u r r e n t p r o b le m s o f r e g io n a l
e c o n o m ic e x p a n sio n , e n v iro n m e n ta l p o llu tio n , la n d s c a p e d e g r a d a tio n , and
s p e c i e s p r e s e r v a t io n , to m e n tio n o n ly th o s e m o s t d ir e c tl y r e l a t e d to s p a tia l
d a ta .
T h e r e s u l t of th e s e d e v e lo p m e n ts h a s b e e n a r a p i d e s c a l a ti o n o f th e
n e e d f o r b e t t e r d e c is io n -m a k in g p r o c e s s e s , in p a r t ic u l a r in n a tio n a l g o v e r n ­
m e n t.
T h e s im p l is tic d ia g r a m of le v e ls o f d e c is io n m a k in g w ith in g o v e r n ­
m e n t g iv e n in C h a p te r 7 (F ig . 7. 4) o b v io u s ly d o e s n o t show th e s t r a i n s and
d is c o n tin u itie s in th e r e l a ti o n s h i p s w h ich a r e in h e r e n t in th e m o r e co m p lex
d e c is io n -m a k in g t a s k s . T o i l l u s t r a t e th e s e , th e d ia g r a m o n th e fo llo w in g
p a g e i s u s e fu l a s a s t a r t i n g p o in t f o r d is c u s s io n .
I t c a n e a s i ly b e u n d e r s to o d th a t p ro b le m s s u c h a s e n v iro n m e n ta l p o llu tio n
m a y c u t a c r o s s th e tr a d iti o n a l li n e s of ju r is d ic tio n of n u m e ro u s g o v e rn m e n t
a g e n c ie s .
G iven a r a t io n a l s ta t e of a f f a i r s , a d a ta b a s e w o u ld b e a v a ila b le
f r o m w h ic h d a ta c o u ld b e e x t r a c te d , m a n ip u la te d , an d r e f o r m a tte d b y
h a n d lin g te c h n iq u e s of v a r io u s ty p e s ; th e r e w o r k e d d a ta w o u ld b e in p u t to
s e le c te d m o d e ls , m e n ta l o r f o r m a l, w h ich w o u ld a p p ly to th e co m p le x
p r o b le m s c o n c e rn e d ; an d d e c is io n s b a s e d on th e m o d e ls w o u ld b e m a d e f o r
s u b s e q u e n t a c tio n .
S om e of th e a s s u m e d r e la tio n s h ip s h a v e a l r e a d y b e e n
1. S im ila r ly (but o u ts id e th e s c o p e o f th i s d is c u s s io n ), th is in te rd e p e n d e n c e
i n c r e a s e s th e a u th o r ity a n d r e s p o n s ib il ity of in te r n a tio n a l a n d g lo b a l
g o v e rn m e n ts , a s i s w itn e s s e d b y th e c r e a tio n of e n titie s s u c h a s th e
C o m m o n M a rk e t in E u ro p e an d th e g ro w th of m u ltin a tio n a l c o r p o r a tio n s .
S ee F o x 1973 f o r a d is c u s s io n of th e c o n flic t b e tw e e n th i s tr e n d a n d th e
s o c ia l and p h ilo s o p h ic a l c o n c e p t of d e m o c ra c y .
269
e x a m in e d in th i s c h a p te r an d th e r e a d e r i s g e n e r a lly a w a r e of: s o m e o f th e
d is c o n tin u itie s in th e p r o g r e s s io n show n in F ig . 8. 4 .
T h e r e is n o t one
d a ta b a s e , b u t m a n y , f r e q u e n tly in c o m p a tib le w ith e a c h o th e r a n d o f v a r io u s
le v e ls of r e l ia b i lit y .
A s h a s b e c o m e a p p a re n t in C h a p te r s 3 to 7, o u r
c a p a b ility f o r h a n d lin g s p a ti a l d a ta in p a r t ic u l a r is in. it s v e r y e a r l y s ta g e s
of d e v e lo p m e n t.
PROBLEM
5
COMPLEX
4
PROBLEM
3
COMPLEX
2
PROBLEM
O rg a n iz a tio n
th e o r y
1
COMPLEX
D e c is io n th e o r y
P O L IC Y D ECISION S
G O V ERN M EN T
A G E N C IE S
M ETHODS O F DATA
A NALYSIS
(M e n ta l an d f o r m a l
m o d e ls)
S p a tia l th e o r y
DATA HANDLING
TE C H N IQ U E S
DATA B A SE
D a ta th e o r y
O b s e rv a tio n a n d m e a s u r e m e n t
D ATA G ATH ERIN G
S im ila r ly , m o d e ls , b o th f o r m a l an d m F
k n ta l, f o r h an d lin g e x t r e m e l y co m p le x
dhrym
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ig.84C
p r o b le m s a r e in a n e m b ry o n ic s ta g e .
W ith o u r p r e s e n t in s titu tio n a l
270
s t r u c t u r e s , p ro b le m s te n d to b e h a n d le d f r o m th e p o in t of view of in d iv id u a l
g o v e rn m e n t a g e n c ie s , r a t h e r th a n in a c o n c e r te d m a n n e r .
I n s te a d o f one
a n s w e r , one m ig h t e x p e c t a s m a n y a p p ro a c h e s to a co m p le x p r o b le m a s
t h e r e a r e g o v e rn m e n t d e p a rtm e n ts .
T h e tr a d iti o n a l re s p o n s e to th is
r e c u r r i n g s itu a tio n is to r e o r g a n iz e th e in s titu tio n s , c r e a tin g new d e p a r t ­
m e n ts .
T o d e a l w ith c r i t i c a l p ro b le m s of h o u s in g an d u rb a n d e v e lo p m e n t,
o n e c r e a t e s a D e p a rtm e n t of H o u sin g a n d U rb a n D evelopm en t,1 f o r p r o b le m s
o f r e g io n a l e c o n o m ic e x p a n sio n , a D e p a rtm e n t of R e g io n a l E c o n o m ic
E x p a n sio n ,2 a n d f o r g rie v o u s p ro b le m s c o n c e rn in g th e e n v iro n m e n t, a
D e p a rtm e n t of th e E n v iro n m e n t.3
T h e a r g u m e n ts in f a v o u r of th i s p r o c e s s a r e th a t new ju r i s d i c ti o n a l b o u n
d a r i e s a r e n e c e s s a r y t o h a n d le th e new p r o g r a m s , th a t th e p r o b le m w a r r a n ts
th e f u ll - tim e c o n c e r n of a s e n io r m i n is te r a n d s ta f f , o r th a t r a tio n a liz e d
f i s c a l p r o g r a m s c a n b e d e v is e d w ith in th e new s tr u c t u r e .
It is s u g g e s te d
th a t t h e r e is a n o th e r u n d e rly in g re a s o n : th e p o w e r of a s in g le in s titu tio n
i s n e c e s s a r y to a c q u ir e a c o n s is te n t body of d a ta to ap p ly to th e co m p le x
p ro b le m .
B e c a u s e of th e r a p id ity w ith w h ic h c o m p le x p r o b le m s s e e m to b e
e m e r g in g , an d th e in e v ita b le o p e r a tio n a l in e f f ic ie n c ie s in h e r e n t in m a jo r
r e s t r u c t u r i n g o f an y l a r g e o r g a n iz a tio n , g o v e r n m e n ts a r e a tte m p tin g to
d e v e lo p te c h n iq u e s th a t w ill allow a m o re e ff ic ie n t r e s p o n s e to co m p lex
p r o b le m s , p a r t i c u l a r l y w h e re th e p r o v is io n a n d h a n d lin g of d a ta a r e c o n ­
c e rn e d .
O ne of th e d if fic u ltie s in s u c h d e v e lo p m e n t, h o w e v e r, is th e la c k
o f a d e q u a te th e o r y a s a gu id e to fu tu r e a c tio n .
T h e v e r y c a te g o r ie s of
th e o ry : d a ta th e o r y , s p a ti a l th e o r y ,4 o r g a n iz a tio n a l th e o r y , a n d d e c is io n
th e o r y , th a t a r e . c e n tr a l to th e g o v e rn m e n t p r o c e s s , a r e a m o n g th e l e a s t
u n d e rs to o d a n d l e a s t a m e n a b le to r ig o r o u s e x p la n a tio n in 1974.
G o v e rn m e n t
in th i s c o m p le x age i s , e v e n m o r e th a n b e f o r e , a g ra n d e x p e rim e n t.
W ith o u t
g o in g f u r t h e r in to th e o v e r a l l p h ilo so p h y of g o v e r n m e n t, it c a n b e o b s e r v e d
th a t a t l e a s t t h r e e m a jo r p h ilo s o p h ie s o f g o v e rn m e n t, e a c h c o v e rin g
a p p ro x im a te ly o n e - q u a r t e r of th e w o r ld 's p o p u la tio n (W e s te rn w o rld ,
M a r x is t- L e n in is t, M a o is t), e x is t s id e b y s id e .
N o one of th e m i s d em o n ­
s t r a b l y " b e t te r " th a n th e o th e r in t e r m s o f g o v e rn m e n ta l o r g a n iz a tio n .
It
is s u g g e s te d th a t e a c h f a c e s th e s a m e w e a k n e s s in t h e th e o r y th a t r e l a t e s to
t h e i r p r o c e s s an d s tr u c t u r e .
1. F o r e x a m p le , HUD, U. S. A. 2. F o r e x a m p le , D R E E , C an a d a. 3. F o r
e x a m p le , D e p a rtm e n t of th e E n v iro n m e n t in s e v e r a l c o u n tr ie s . 4. T h e
r e s t r i c t i o n to s p a ti a l th e o r y h e r e i s w ith r e s p e c t to th e t e r m s o f th i s t h e s i s .
271
T h e r e l a ti o n s h i p a m o n g th e th e o r ie s u n d e rly in g th e p r o c e s s o f g o v e rn m e n t
i s o u ts id e th e s c o p e o f th i s d is c u s s io n , b u t m u s t b e in c o r p o r a te d in fu tu r e
w o rk r e l a ti n g to th e d e v e lo p m e n t of in fo rm a tio n s y s t e m s .
In th e in te r im ,
lin e s of d e v e lo p m e n t th a t m ig h t b e n e fit a n d h a v e a p r a g m a tic in flu e n c e on
th e r e s p o n s e of d e c is io n m a k in g to d e v e lo p m e n ts in g e o g ra p h ic in fo rm a tio n
s y s t e m s a n d s p a ti a l a n a ly s is w ill b e s u g g e s te d .
I n s titu tio n a l D a ta L in k a g e s
P e r h a p s th e f i r s t lin e of d e v e lo p m e n t th a t c a n b e s u g g e s te d i s a n in c r e a s e
o f in te r a g e n c y d a ta lin k a g e s .
C e r ta in ly th i s g o e s c o u n te r to th e c o n c e r n s
of e x is tin g in s titu tio n a l p o w er (but if it w e r e p o in te d out th a t a n a lte r n a tiv e
w a s a d e c lin e in in d iv id u a l in s titu tio n a l r e s p o n s ib il ity a n d th e g ro w th o f
in c r e a s in g ly c e n tr a li z e d p o w e r in s u p e r d e p a r tm e n ts , th e in d iv id u a l in s ti tu ­
tio n s m ig h t fin d s u c h jo in t a c tio n a t tr a c t iv e ) .
H o w e v e r, s te p s 1 to w a rd
c o m p a tib ility o f d a ta b e tw e e n a g e n c ie s a r e b e in g ta k e n (ev en if th e y a r e
b e in g w a tc h e d e x t r e m e l y w a r ily b y th e in s titu tio n s c o n c e rn e d ).
In f a c t,
th e n e e d f o r in s titu tio n s to b e e ffe c tiv e a s w e ll a s p o w e rfu l h a s e n c o u ra g e d
th e tr e n d to w a r d c o m p a tib le d a ta .
O ne a p p ro a c h to th i s lin e of d e v e lo p m e n t i s to c r e a t e " m in i- in s titu tio n s "
w h ic h a r e r e s p o n s ib le f o r g a th e r in g in te r a g e n c y d a ta .
O ne o f th e f i r s t
e x a m p le s of th i s w a s th e C e n tr a l S ta t is tic a l O ffice in G r e a t B r ita in , d u rin g
W o rld W a r II.
I t w a s e s ta b lis h e d to r e s o lv e a r g u m e n ts a r i s i n g f r o m c o n ­
f lic tin g f ig u r e s g iv e n to th e C ab in et by v a r io u s d e p a r tm e n ts , a n d to p ro v id e
th e f r a m e w o r k of n a tio n a l a c c o u n tin g n e e d e d to m a n a g e th e o v e r a l l d em an d in
th e e c o n o m y a c c o r d in g to K e y n e s ia n p r in c ip le s .
(N ote th a t th e s t r e s s o f w a r ,
th e n e e d to u n d e r s ta n d a co m p lex s itu a tio n , a n d th e s p e c if ie d n e e d f o r
rig o r o u s e x p la n a tio n w e r e f a c t o r s th a t in d u c e d in s titu tio n a l c o m p lia n c e .) T h e
B u s in e s s S ta t is tic s O ffice2 p ro p o s e d in G re a t B r it a in , in te n d e d to g a th e r
a l l d a ta f r o m a l l in d u s tr i a l e s ta b lis h m e n ts f o r s u b s e q u e n t u s e b y a l l d e p a r t­
m e n ts n e e d in g th e m , fo llo w s th e c o n c e p t o f th e f i r s t e x a m p le .
A s e c o n d a p p ro a c h i s th e e s ta b lis h m e n t of new te c h n ic a l g u id e lin e s f o r d a ta
h a n d lin g .
A tim e of c h a n g e , s u ch a s d u rin g th e tr a n s i tio n f r o m m a n u a l to
1. T h e p r o c e s s h a s r e c e iv e d s o m e im p e tu s f r o m th e ad v e n t o f c o m p u te r s a s
in fo rm a tio n p r o c e s s o r s . A s th e c h a n g e o v e r f r o m m a n u a l to c o m p u te r p r o ­
c e s s in g i s m a d e , t h e r e c a n b e an a tte m p t ( s o m e tim e s a t th e te c h n ic a l le v e l
r a t h e r th a n th e p o lic y le v e l) to m a k e d a ta s e t s c o m p a tib le (g iv en g u id e lin e s,
c o m p e te n c e , an d r e s o u r c e s ) . J u s t a s e a s ily , h o w e v e r, s u c h a m o v e m en t
c a n b e f r u s t r a t e d , a n d th e in c o m p a tib ility of d a ta c a n b e e n s h r in e d in
c o m p u te r s to r a g e . 2. B r a y 1970.
272
c o m p u te r d a ta p r o cessing, provides opportunities for such innovations.
W ithout legislative underpinnings, how ever, this approach is less
lik e ly to b e su c c e ssfu l in a tim e o f m e th o d o lo g ic a l s ta b ility . A n e x a m p le is th e
current effort of the D epartm ent of Environm ent in G reat Britain to guide the spatial
e n c o d in g o f u rb a n d a ta to w a rd p o in t d a ta sy ste m s.1 A th ird a p p ro a c h is th e
provision of technical expertise, the central training of techn ician s resp o n sib le
for designing new data structures. A gain, this approach is prim arily useful in a
tim e of m ethodological change. It is being attem pted in a p ro g ram ex ten d ed to
225 cities in the U . S. A.,2 and underlies the program of the Centre d'Études et de
R echerches sur les Collectivités Locales en Europe (C. E. R. C . L. E.)3 proposed
in France for the training of m iddle levels of governm ent staff in the
technolgyofdathndlig.A
thirdapochistaofhe"pilotsudy".A
nexam
pleofth i s c a n b e ta k e n f r o m F r a n c e : th e O pé r a tio n P ilo te Int e r m i n i s t é r i e l l e
sur l e s D onné e s A d m in i s t r a tiv e s 4 h a s b e e n e s ta b lis h e d a t n a tio n a l le v e l in
d e p a rtm e n ts of g o v e rn m e n t w ith th e s p e c ific o b je c tiv e of in te g r a tin g i n s t i tu
tio n a l d a ta f o r p la n n in g in th e South of F r a n c e .
T h e a im o f th i s e x e r c is e
i s e v e n tu a lly to m a k e th e d a ta in th e v a r io u s g o v e rn m e n t a g e n c ie s c o m p a tib le
andnot to e s t a b lis h a new ag e n cy .
T h e fo u rth a p p ro a c h i s to r e q u i r e
c o m p a tib le d a t a s o u r c e s b y le g is la tio n , a s
funds fr o m a c e n t r a l s o u r c e .
p r i o r c o n d itio n f o r r e c e iv in g
A n e x a m p le of th is is th e J a c k s o n B il l5
c u r r e n t l y b e in g d e b a te d b y th e U .S . S en ate, w h ich w ill r e q u i r e e v e r y s ta t e
to
ha v e a s u r v e y of p r e s e n t la n d u s e , c o m p u te r - s to r e d in a c o m p a tib le
of r m a t, a s a b a s i s f o r f u tu r e g r a n ts f o r f e d e r a l la n d p la n n in g a n d d ev e lo p m en t.
T h e d e g r e e to w h ich th e s e a p p ro a c h e s a r e n e e d e d and w ill a c h ie v e s u c c e s s
v a rie s .
A s p o in te d out in C h a p te r 2, th e exi s ti n g le v e l of d a ta c o m p a tib ility
b e tw e e n g o v e rn m e n t d e p a rtm e n ts v a r i e s m a rk e d ly f r o m one c o u n try to
a n o th e r .
T h e 4 0 0 - y e a r - o l d tr a d iti o n o f o p en C e n tr a l R e g i s t e r s in Sw eden
c o n t r a s ts w ith th e m o r e c o n fid e n tia l a n d fle x ib le a p p ro a c h to d a ta g a th e r in g
in
r e a t B r ita in , w h ich c o n t r a s ts in tu r n w ith th e im m e n s e c o m p le x itie s due
G
t o s iz e a n d a f e d e r a l s y s t e m of g o v e rn m e n ts in th e U .S . A.
N e v e r th e le s s
th e d e v e lo p m e n t of in t e r - in s ti tu ti o n d a ta lin k a g e s w ill h av e c o n s id e r a b le
im p a c t o n th e su p p ly of d a ta a v a ila b le an d on th e ty p e of d e c is io n m a k in g
l . D e p a rtm e n t o f E n v iro n m e n t, U . K . 1 9 7 3 . 2 . U . S . B u r e a u o f C e n su s 1 9 7 3 .
3. T
4.Shael ma uo nt hao 1r i s a m e m b e9 r o f t h e s t e e7 r i n g c o m m 4i t t e e f o r t h i s. p r o g r a m .
5 .N a tio n a l L a n d U s e P o lic y a n d P la n n in g A s s is ta n c e A c t, S 2 6 8 ,
9 3 r d C o n g re s s o f U . S . A ., 1 s t S e s s io n . S e e a ls o C a lk in s e t a l. 1 9 7 3 .
273
th a t c a n b e n e fit f r o m im p r o v e d te c h n iq u e s f o r h a n d lin g s p a ti a l d a ta an d
im p r o v e d f o r m a l s p a ti a l a n a ly s is (and v ic e v e r s a ) .
D e s ig n of F o r m a l S p a tia l M o d els
T h e d e v e lo p m e n t of ty p e s o f f o r m a l s p a ti a l a n a ly s is th a t a r e m o r e v a lu a b le to
g o v e rn m e n t d e c is io n m a k in g th a n th o s e c u r r e n t ly a v a ila b le w ill c e r t a in l y b e
e n c o u ra g e d b y d e v e lo p m e n ts w ith in th e d is c ip lin e o f g e o g ra p h y a n d b y c o m ­
p a r a b le i n c r e a s e s in s u p p lie s of c o m p a tib le d a ta w ith in g o v e rn m e n t.
R eal
im p r o v e m e n t, h o w e v e r, m u s t r e l y to a g r e a t e x te n t o n in c r e a s e d c o m m u n i­
c a tio n b e tw e e n m o d e l d e s ig n e r s an d d e c is io n m a k e r s . I t i s d iffic u lt to ta k e
a n o b je c tiv e view o f th e s itu a tio n an d d e c id e w h ic h g ro u p i s h e s it a n t, and
w hy.
S im p le m o d e ls , w h ic h r e l a t e to th e in tu itiv e m o d e ls o f d e c is io n m a k e r s ,
f r e q u e n tly s e e m to b e in a d e q u a te f o r d e c is io n m a k in g b e c a u s e o f th e in f le x i­
b il ity of t h e i r in h e r e n t a s s u m p tio n s (a s s u m p tio n s u s e d v e r y fle x ib ly in
m e n ta l m o d e ls ).
M o re c o m p le x m o d e ls , w h ich a tte m p t to b e fle x ib le w ith
r e s p e c t to th e s a m e a s s u m p tio n s , do n o t r e l a t e to th e in tu itiv e m e n ta l m o d e ls
of d e c is io n m a k e r s , a r e in c o m p r e h e n s ib le to a n u n tr a in e d m in d , an d ,
d e s p ite t h e i r s ta t e of d e v e lo p m e n t, a r e s t i l l a w k w ard to o l s .
T h e r e la tio n s h ip
i s c o m p lic a te d b y th e f a c t th a t g o v e rn m e n ta l d e c is io n s a r e f r e q u e n tly m a d e
in u r g e n t r e s p o n s e to p ro b le m s (th e y o p e r a te in " r e a l tim e " ) w h ile th e d e s ig n
a n d te s t in g of r e l e v a n t m o d e ls m a y ta k e m o re tim e th a n i s a v a ila b le b e f o r e
s u c h d e c is io n s h a v e to b e m a d e (th e y o p e r a te " o ff -lin e " ).
T h e re a r e som e
e x a m p le s o f m o d e ls b e in g in t e g r a t e d w ith th e d e c is io n - m a k in g p r o c e s s w ith in
a n in s titu tio n a l f r a m e w o rk .
T h e u r b a n tr a n s p o r t a ti o n m o d e ls b a s e d on th e
w o r k of G a rin an d L o w ry a r e w e ll e s ta b lis h e d in P i tt s b u r g h , U . S. A .
S ub­
r e g io n a l g ro w th a n d a llo c a tio n m o d e ls a r e in ro u tin e u s e in E n g la n d in
L e i c e s t e r s h i r e , C h e s h ir e , an d H a m p s h ire .
T h e S w e d ish G o v e rn m e n t e m p lo y s
q u ite s o p h is tic a te d m o d e ls of r e g io n a l g ro w th a s a n in t e g r a l p a r t o f p o lic y an d
p la n n in g d e c is io n s .
T h e t r e n d i s , h o w e v e r, in i t s in fa n c y .
T he c u rre n t
o v e r a l l s itu a tio n c o u ld p ro b a b ly b e s u m m a riz e d b y s a y in g th a t t h e r e a r e few
f o r m a l m o d e ls u s e fu l to th e d e c is io n -m a k in g p r o c e s s on a r e c u r r i n g b a s i s ,
a n d t h e r e i s a w id e s p r e a d la c k of c o m p re h e n s io n of s p a t i a l a n a ly s is o n th e
p a r t of d e c is io n m a k e r s .
I t c a n , h o w e v e r, b e n o te d th a t th e d e v e lo p m e n t of s p a ti a l m o d e ls in r e c e n t
274
y e a r s h a s c l o s e ly fo llo w e d th e c o n c e r n s of s o c ie ty .
T h e w id e s p r e a d d e v e lo p ­
m e n t of tr a n s p o r t a ti o n an d u r b a n m o d e ls h a s b e e n in r e s p o n s e to g o v e r n m e n ­
t a l p ro b le m s of tr a n s p o r t a ti o n an d u rb a n d e v e lo p m e n t.
D o u b tle ss th e
n u m b e r of e n v iro n m e n ta l m o d e ls w ill in c r e a s e in th e n e a r f u tu r e .
I n th e
o p in io n of th e a u th o r , a n e x p r e s s e d n e e d f o r e x p la n a tio n an d th e fu n d s to
s u p p o r t r e s e a r c h e l i c i t s a s tr o n g re s p o n s e f r o m m o d e l d e s ig n e r s .
A s s u m in g th a t c a p a b ilitie s f o r d a ta g a th e rin g an d h a n d lin g h a v e b e e n
d e v e lo p e d , t h r e e f a c t o r s a r e n e e d e d to e n c o u ra g e th e d e v e lo p m e n t o f b e t te r
m o d e ls f o r d e c is io n m a k in g : i n c r e a s e d p e r c e p tio n , a n tic ip a tio n , a n d
c o m p re h e n s io n o n th e p a r t of d e c is io n m a k e r s .
I t is c l e a r th a t a d e c is io n
m a k e r m u s t b e a b le to p e r c e iv e th a t f o r m a l a n a ly s is c a n a p p ly to th e t a s k s
th a t f a c e h im .
B e fo r e s u c h te c h n iq u e s ca n b e d e v is e d , th e n e e d f o r th e m
m u s t b e a n tic ip a te d , to allo w th e le a d tim e r e q u i r e d f o r m o d e l d e v e lo p m e n t.
T h is in v o lv e s a c h a n g e in m o d e of g o v e rn m e n t f r o m o n e o f r e s p o n s e to
c r i s e s to t h e i r a n tic ip a tio n , w h ic h in i t s e l f w ill b e a m a jo r ch a n g e f o r g o v e r n ­
m e n ts .
T h e t h i r d f a c t o r , c o m p re h e n s io n , im p lie s th a t th e f o r m a l tr a in in g
of d e c is io n m a k e r s in c lu d e s s u b je c ts th a t allow h im to u n d e r s ta n d (an d
d e p e n d upon) th e te c h n iq u e s b e in g u s e d .
O f th e s e t h r e e f a c t o r s , a n tic ip a tio n i s p ro b a b ly th e l e a s t c r i t i c a l , a s to s o m e
e x te n t i t c a n b e a c o o p e ra tiv e p r o c e s s b e tw e e n m o d e l b u il d e r s a n d d e c is io n
m a k e r s w ith o u t c lo s e c o n ta c t.
T h e m o d e l b u ild e r s th e m s e lv e s c a n , to s o m e
e x te n t, o b s e r v e s o c ie ty 's t r e n d s a n d d ir e c t r e s e a r c h a c c o r d in g ly .
The
f a c t o r s o f p e r c e iv e d n e e d f o r f o r m a l a n a ly s is a n d i t s s u b se q u e n t c o m p r e h e n ­
s io n , h o w e v e r, r e l y m a in ly on th e tr a in in g of th e d e c is io n m a k e r s .
P o s t - U n i v e r s ity T r a n s f e r of T e c h n o lo g y to D e c isio n M a k e rs
O ne c a n h o p e th a t c u r r e n t c o u r s e s of h ig h e r e d u c a tio n w ill p ro v id e a n a d e ­
q u a te s u p p ly o f w e ll - tr a in e d p e o p le w ho w ill e v e n tu a lly p a r t ic i p a te i n th e
d e c is io n -m a k in g le v e ls o f g o v e rn m e n t.
O f m o r e im m e d ia te c o n c e r n a r e
th e p e o p le w ho h a v e c o m p le te d t h e i r f o r m a l a c a d e m ic tr a in in g a n d w h o w ill
in flu e n c e d e c is io n m a k in g in g o v e rn m e n t in th e n e x t d e c a d e .
T h e e x p e rie n c e
o f th e U . S. B u re a u of th e C e n s u s in a r e c e n t s e r i e s of W o rk s h o p s f o r
tr a in in g lo c a l g o v e rn m e n t o f f ic ia ls in th e te c h n iq u e s of th e D IM E s y s t e m
i l l u s t r a t e s th e s itu a tio n .
1. S e e C h . 4 , p p . 1 1 6-122.
T h e o b je c tiv e s of th e w o r k s h o p s (e a c h 5 d a y s long)
275
w e r e to e n s u r e " th a t th e in h e re n t c a p a b ilitie s of th e DIM E s y s t e m f a c ilitie s
c a n b e u tiliz e d b y th o s e im p le m e n tin g it in w o rk in g e n v iro n m e n ts a n d . . . to
p ro v id e a fe e d b a c k p r o c e s s s o th a t th e co n tin u in g d e s ig n of th e DIM E s y s te m
f a c i l i t i e s c a n b e c a r r i e d out in r e s p o n s e to e x p r e s s e d u s e r n e e d s an d
p r o b le m s . "
T h e w o rk s h o p s w e r e h e ld a t r e g io n a l c e n tr e s in th e U. S. A.
(In d ia n a p o lis , A tla n ta , P itt s b u r g h , B o s to n , a n d San F r a n c i s c o ) .
A p p ro x i­
m a te ly 200 p e o p le f r o m m id d le le v e ls of m a n a g e m e n t in u r b a n an d
r e g io n a l g o v e rn m e n t a tte n d e d .
T h e a u th o r w a s a m e m b e r of th e a d v is o r y
c o m m itte e f o r th e w o rk s h o p s a n d a tte n d e d f o u r of th e m .
Q u ite s im p ly ,
th e w o rk s h o p s sh o w e d th a t a k e y f a c t o r in u s e of th e D IM E s y s t e m w a s th e
a b ility of th e u s e r s to a p p ro a c h p la n n in g p r o b le m s in a m a n n e r th a t r e q u i r e d
th e ty p e o f d a ta th e s y s t e m c o u ld p ro v id e .
A s th e D IM E s y s t e m is f a i r ly
w e ll d e v e lo p e d , q u ite fle x ib le , a n d r e a s o n a b l y e ffic ie n t, th e lim itin g
f a c t o r w a s th e c o m p e te n c e of th e p la n n e r s to a p p r o a c h t h e i r p r o b le m s in
q u a n tita tiv e t e r m s , to th in k in s p a ti a l t e r m s , an d , in g e n e r a l, to b e a b le
to ta k e a d v a n ta g e of th e d a ta s y s t e m c a p a b ilitie s .
T h is la c k o f tr a in in g h a s
e q u a l im p a c t o n th e p e r c e iv e d n e e d f o r a n d u n d e rs ta n d in g o f f o r m a l s p a tia l
a n a ly s is , a n d th e d e s ig n a n d u s e of g e o g ra p h ic in fo rm a tio n s y s te m s to
p ro v id e d a ta f o r b o th f o r m a l an d m e n ta l m o d e ls .
T h e f a c t r e m a in s th a t few s t r u c t u r e s i n o u r s o c ie ty allow th e p o s t- u n iv e r s i ty
t r a n s f e r of a d v a n c e d te c h n o lo g y to a d m in is tr a to r s an d d e c is io n m a k e r s , who
m o s t n e e d to b e a w a r e of i t s p o te n tia lity .
I t i s c l e a r th a t o n e lin e of d e v e ­
lo p m e n t m u s t b e a n i n c r e a s e in f o r m a l a n d in f o r m a l p o s t- u n iv e r s i ty
e d u c a tio n , w h e th e r it b e in th e f o r m of s a b b a t ic a l s , s u m m e r c o u r s e s ,
s h o r t c o u r s e s , s e m i n a r s , w o r k s h o p s , a u d io - v is u a l p r e s e n t a tio n s , c o m p u te r a id e d in s tr u c tio n , p ro g r a m m e d in s tr u c tio n , s e lf - t e a c h i n g m a n u a ls o r an
a p p r o p r ia te m ix tu r e .
A g ain , th e d e ta ile d a p p ro a c h to b e fo llo w e d m u s t
d ep e n d o n fu tu r e stu d y .
W hat i s im p o r ta n t i s th a t s u c h tr a in in g b e c o m e s
m o r e r e a d i l y a v a ila b le , a n d b e c o m e s an in t e g r a l p a r t of th e c a r e e r p a th of
d e c is io n m a k e r s .
A s a n i n t e r i m m e a s u r e , it i s s u g g e s te d th a t th o s e c o n ­
c e rn e d w ith f o r m a l s p a ti a l a n a ly s is , a n d in p a r t i c u l a r w ith th e d e s ig n o f
g e o g ra p h ic in f o rm a tio n s y s t e m s , u n d e r s ta n d th a t i t i s n e c e s s a r y to b u ild
u s e r c o m p e te n c e in q u a n tita tiv e m e th o d s of p r o b le m s o lv in g , a s w e ll a s to
b u ild in fo r m a tio n s y s t e m s a n d f o r m a l a n a ly tic a l c a p a b ilitie s .
l . S ee U. S. B u re a u of C e n s u s 1973.
276
I n te r a c ti o n B etw e en D ata G a th e r e r s an d D ata U s e r s
T h e m a n d a te of d e p a rtm e n ts of g o v e rn m e n t th a t tr a d iti o n a ll y g a th e r d a ta
(c e n s u s an d s u rv e y ) is to p ro v id e d a ta r e l a ti n g to th e p e r c e iv e d n e e d s of
g o v e rn m e n t im p a r ti a ll y to a l l d e p a rtm e n ts of g o v e rn m e n t (an d to a l e s s e r
d e g r e e , to a l l o th e r p u b lic a n d p r iv a te u s e r s ) .
d a te .
T h is is a v e ry b ro ad m a n ­
A s th e t a s k s fa c in g s u c h d a ta g a th e rin g d e p a rtm e n ts h a v e in c r e a s e d ,
an d a s th e d e la y b e tw e e n th e n e e d f o r d a ta an d t h e i r r e c e i p t h a s b e c o m e
m o r e c r i t i c a l , th e lin e d e p a rtm e n ts of g o v e rn m e n t h a v e h a d in c r e a s in g
r e a s o n to u s e t h e i r ow n a d m in is tr a tiv e n e tw o rk s (fr e q u e n tly m o r e e x te n s iv e
th a n th o s e of d a ta g a th e rin g a g e n c ie s ) to c o lle c t d a ta r e l a t e d to t h e i r ow n
o p e r a tio n s .
d a ta .
N e v e r th e le s s , d a ta g a th e r in g a g e n c ie s g a t h e r l a r g e a m o u n ts of
A lthough s u c h d a ta n e c e s s a r i l y a r e b ia s e d b y th e a g e n c ie s ' i n t e r p r e ­
ta tio n of th e " p e r c e iv e d n e e d s o f g o v e rn m e n t" , th e y a r e o th e r w is e im p a r ti a l
an d in t e r n a l ly c o n s is te n t.
T h e r e a r e tw o s u b s ta n tia l d ra w b a c k s to th e p r e s e n t s itu a tio n .
F i r s t , th e
d e p a r tm e n ts ' in t e r p r e ta tio n of an d r e a c tio n to th e p e r c e iv e d n e e d s of
g o v e rn m e n t m a y c a u s e d a ta to b e g a th e re d w ith o u t l a t e r u s e ; a n d o n ce d a ta
c o lle c tio n h a s b e g u n , t h e r e is a te n d e n c y f o r it to co n tin u e if o n ly f o r th e
s a k e of co n tin u ity .1
S econdly, th e p r o c e s s of fe e d b a c k f r o m g o v e rn m e n t,
th e s p e c ific a tio n of th e p e r c e iv e d n e e d s of g o v e rn m e n t b y g o v e rn m e n t, is
s u b s ta n tia lly f i l t e r e d th ro u g h th e in te rv e n in g lin e d e p a rtm e n ts o r d o e s n ot
o c c u r a t a l l.
T h e s e d r a w b a c k s p la c e a g r e a t d e a l of r e s p o n s ib ility o n th e
s h o u ld e r s of th e d a ta g a th e rin g d e p a rtm e n ts a n d p e r h a p s i n c r e a s e th e d a n g e r
of ir r e l e v a n t d a ta b e in g g a th e r e d o r of lin e d e p a rtm e n ts b e in g e n c o u ra g e d to
g a th e r t h e i r ow n " r e le v a n t" d a ta .
A t th e s a m e ti m e , th e te c h n iq u e s an d
c a p a b ilitie s f o r g a th e rin g d a ta a r e ra p id ly im p ro v in g .
In th e s u r v e y p r o ­
f e s s io n in p a r t i c u l a r , t h e r e h av e b e e n s p e c t a c u la r d e v e lo p m e n ts in r e c e n t
y e a r s in th e c a p a b ility f o r g a th e rin g to p o g ra p h ic a n d th e m a tic s p a tia l d ata.
T h e a d v a n c e s in c o n v e n tio n a l a e r i a l p h o to g ra p h y , a u to m a tic p h o to g r a m m e tr y ,
o rth o -p h o to g ra p h y , m u ltis p e c tr a l s e n s in g , s a t e l l i t e s e n s o r p la tf o r m s ,
h e l ic o p t e r r e c o n n a is s a n c e s u r v e y s , s p a tia l s a m p lin g te c h n iq u e s , and a u to ­
m a tic c a rto g r a p h y r e p r e s e n t a g r e a t in c r e a s e in th e te c h n o lo g y of d a ta
g a th e r in g an d d is p la y , w h ich w ill b e e x e r c is e d p r i m a r i l y b y tr a d itio n a l
1. T h e i n e r t i a in th e s y s t e m i s not n e c e s s a r i ly b a d . C o n tin u ity of d a ta s e ts
i s a v a lu a b le p ro p e rty . T h e in e r tia , h o w e v e r, a f f e c ts b o th u s e f u l an d u s e le s s
d a ta . T h e p r o b le m li e s in e s ta b lis h in g c r i t e r i a f o r d is tin g u is h in g b etw e en
th e m .
277
d a ta g a th e r in g in s titu tio n s :
We a r e u n d o u b te d ly in a p o s itio n w h e r e w e can
g a t h e r h u g e a m o u n ts of d a ta , w h ich w e m a y o r m a y n o t b e a b le to h a n d le ,
a n d w h ich w e m a y o r m a y n o t n ee d .
C le a r ly , i n c r e a s e d fe e d b a c k f r o m th e
p o lic y m a k in g le v e ls of g o v e rn m e n t i s n e e d e d to id e n tify w h ich d a ta c o u ld
p r o f ita b ly b e c o lle c te d an d , p e r h a p s e q u a lly im p o r ta n tly , to p r o v id e th e
c r i t e r i a f o r d e lim ita tio n .
S uch r e v i s i o n w ill n o t o c c u r q u ic k ly .
No m e c h a n is m s a r e in p la c e to im p ro v e
th e fe e d b a c k , an d t h e r e is s u b s ta n tia l m o m e n tu m to th e g a th e r in g o f c u r r e n t
d a ta s e t s .
I n c r e a s e s in th e to t a l su p p ly (of b o th w a n te d an d u n w an te d d ata)
a n d p o s s i b le o v e rlo a d in g of s to r a g e an d h an d lin g c a p a c ity f o r s o m e ty p e s of
d a ta , a r e lik e ly to o c c u r b e f o re b e t t e r fe e d b a c k h a s a g r e a t e r in flu e n c e in
th e s e le c ti o n of d a ta to b e g a th e re d .
P e r h a p s th e f i r s t im p ro v e m e n ts in fe e d b a c k to th e d a ta g a th e r in g a g e n c ie s
th a t p ro v id e s p a ti a ll y co d e d d a ta w ill c o m e f r o m th e u s e o f g e o g ra p h ic in f o r ­
m a tio n s y s t e m s .
O nly w hen d a ta a r e a c tu a lly r e a d 1 an d u s e d in m e n ta l o r
f o r m a l m o d e ls , a n d it c a n b e sh o w n th a t c o n ten t o r f o r m a t c h a n g e s a r e
n e c e s s a r y o r th a t o th e r d a ta m ig h t b e p ro f ita b ly c o lle c te d w ith th e s a m e
e x p e n d itu r e of fu n d s , is t h e r e a n y lik e lih o o d th a t p e r s u a s io n ca n b e b ro u g h t
to b e a r o n tr a d iti o n a l d a ta g a th e rin g a g e n c ie s to a m e n d t h e ir s ta n d a r d f o r m s
o f o p e r a tio n .
T h e s e c o n d le v e l o f im p ro v e m e n t in fe e d b a c k w ill c o m e w hen im p ro v e d s p a ti a l
m o d e ls a r e in t e g r a t e d in to th e d e c is io n -m a k in g p r o c e s s an d c a n b e u s e d to
s p e c if y d a ta r e q u i r e m e n t s .
p r o c e s s a s w e know i t to d a y .
T h is im p lie s a change in th e d e c is io n - m a k in g
A s u b s ta n tia l d e g r e e of in te g r a tio n o f f o r m a l
te c h n iq u e s in th e d e c is io n -m a k in g p r o c e s s w ould b e n e e d e d b e f o r e t h e i r d a ta
n e e d s w o u ld r e p r e s e n t a s tr o n g a rg u m e n t f o r ch a n g in g e s ta b lis h e d d a ta
g a th e r in g p r a c t i c e .
T h e p o s s ib ility of s u c h c h a n g e s in th e d e c is io n - m a k in g
p r o c e s s i s e x a m in e d below .
I n te r a c ti o n B e tw e e n D ata S p e c ia lis ts a n d D e c isio n M a k e rs
S e v e r a l s t r a n d s of th o u g h t ru n th ro u g h th e d is c u s s io n in th e l a t t e r p a r t of
th i s c h a p te r .
T h e d e c is io n -m a k in g p r o c e s s , a s h a s b e e n s e e n , r e l i e s
p r i m a r i l y o n m e n ta l m o d e ls .
F o r m a l m o d e ls h a v e a v a lu a b le p a r t to p la y
i n d e c is io n m a k in g , b u t d e c is io n m a k e r s g e n e ra lly la c k a c l e a r c o m p re h e n s io n
1. T h e b e n e fit of e v e n th e c u r r e n t le v e l of te c h n iq u e s f o r h an d lin g s p a ti a l d a ta
i s th a t i t i s now p o s s ib le to e x a m in e th e d a ta p re v io u s ly c o lle c te d , b u t not
b e f o r e a m e n a b le to e c o n o m ic u s e .
278
o f t h e i r c a p a b ilitie s .
G e o g ra p h ic in fo rm a tio n s y s t e m s h a v e b e e n d ev e lo p ed
m a in ly in r e s p o n s e to s o u r c e s of d a ta an d th e n e e d s of m e n ta l m o d e ls .
They
w ill b e f u r t h e r d e v e lo p e d to h a n d le i n c r e a s e s in th e g a th e r in g o f s p a tia l d a ta ,
in th e s t o r e s of s p a ti a ll y c o d e d , m a c h in e - r e a d a b le , e x is tin g d a ta , an d in th e
d e m a n d s of f o r m a l m o d e ls .
T h e c o n c e rn s of g o v e rn m e n t a r e o b s e rv a b ly
b e c o m in g m o r e co m p le x an d im p ro v e m e n ts in d e c is io n - m a k in g p r o c e s s e s
a r e n e e d e d w ith in th e o r g a n iz a tio n a l s t r u c t u r e o f g o v e rn m e n t.
In th e s h o r t t e r m , t h e r e is an o b v io u s n e e d to i n c r e a s e th e c o m m u n ic a tio n
b e tw e e n d e c is io n m a k e r s a n d th o s e c o n c e rn e d w ith th e p ro v is io n , h an d lin g ,
a n d a n a ly s is of d a ta .
C o m m u n ic a tio n in th i s s e n s e d o e s n o t s im p ly r e f e r to
a n e x c h a n g e of in f o rm a tio n , b u t im p lie s " n e g o tia tio n " .
T h e c o n c ep t u n d e r ­
ly in g th i s s u g g e s tio n i s th a t d e c is io n s a r e n o t m a d e f r o m th e d a ta th e m s e lv e s
o r f r o m d a ta p ro v id e d b y m e n ta l o r f o r m a l m o d e ls , b u t f r o m th e im a g e s
th a t th e d a ta c r e a t e .
In th e a b s e n c e of d a ta , o r an y f o r m of a n a ly s is o f d a ta ,
th e im a g e m a y b e b la n k o r p re c o n c e iv e d , b u t th a t d o e s no t a l t e r th e f a c t
th a t th e d e c is io n is m a d e f r o m th e im a g e . 1 T h e im p a c t of d a ta , an d th e
a n a ly s is of d a t a , o n a d e c is io n i s th u s th e e x te n t to w h ich th e im a g e is
c r e a te d o r c h a n g e d b y th e d a ta o r a n a ly s is .
T h e fu n c tio n of th e d e s ig n e r of
an in fo r m a tio n s y s t e m o r a f o r m a l m o d e l in d e c is io n -m a k in g t e r m s i s to
p ro v id e o u tp u t th a t h a s im p a c t on th e im a g e .
T h e f le x ib ility o f th e p r o c e s s
(in th e c o n te n t a n d m a n ip u la tio n f a c i li tie s o f in fo rm a tio n s y s t e m s , an d in th e
ty p e s of f o r m a l a n a ly s is ) i s th a t im a g e s m a y b e g e n e ra te d o r c h a n g ed b y
one of a n y n u m b e r of s u b s e ts of th e d a ta o r ty p e s of a n a ly s is n e e d e d to
q u a n tify th e im a g e c o m p le te ly .
T h e r e q u i r e d c o m m u n ic a tio n p r o c e s s is
th u s o n e th a t n e g o tia te s th e in te r f a c e b e tw e e n th e im a g e an d th e d a ta ; th a t
n e g o tia te s b e tw e e n d e c is io n m a k in g a n d th e p r o c e s s e s of in fo rm a tio n s y s te m
d e s ig n a n d f o r m a l a n a ly tic a l d e s ig n .
T h e o u tc o m e of n e g o tia tin g th e i n t e r ­
f a c e b e tw e e n d e c is io n an d d a ta w ould b e a new view a n d u n d e rs ta n d in g o f
d a ta th a t th o s e c r e a tin g a n d m a in ta in in g d a ta b a n k s an d in fo rm a tio n s y s te m s
f r e q u e n tly la c k .
S im ila r ly , it w ould m e a s u r a b ly a s s i s t th e d e s ig n of f o r m a l
m o d e ls th a t c o u ld b e in te g r a te d in to th e d e c is io n -m a k in g p r o c e s s e s .
In g e n e ra l, th e s t r u c t u r e s th a t w ould allow th e n e e d e d co m m u n ic a tio n b e tw e e n
1. If a p e r s o n kn o w s a b s o lu te ly n o th in g ab o u t a s u b je c t, e. g. , lif e in o u te r
s p a c e , h e i s q u ite c a p a b le of m a k in g a d e c is io n ab o u t it, e ith e r f r o m a b la n k
im a g e o r a n im a g e b a s e d on a b s o lu te ly no e v id e n c e . G iven d a ta , h e ca n p r o ­
c e s s th e m e i th e r m e n ta lly o r f o r m a lly a n d a r r i v e a t a c o n c lu s io n , w h ich m a y o r
m a y n o t a l t e r h is im a g e . In t h i s s e n s e an im a g e i s a n a b s tr a c tio n o f a m e n ta l m o d e l;
th e f o r m e r i s a m e n ta l s ta t e , th e l a t t e r a m e n ta l d a ta p r o c e s s in g p r o c e d u r e .
279
d a ta s p e c i a li s t s an d d e c is io n m a k e r s a r e n o t now co m m o n in g o v e rn m e n t a t
lo c a l, re g io n a l, o r n a tio n a l le v e ls .
a r e a l n e e d of lo c a l g o v e rn m e n t.
T h e d e v e lo p m e n t of s u c h s t r u c t u r e s i s
T h e n e e d is c r i t i c a l a t r e g io n a l an d n a tio n a l
le v e ls p a r t ic u l a r ly , to p e r m it in t e r a c t io n b e tw e e n th o s e c o n c e r n e d w ith
m u l ti- j u r is d ic t io n a l p o lic y an d th o s e c o n c e rn e d w ith p ro v is io n an d a n a ly s is
o f d a ta .
Such a s t r u c t u r e co u ld in c lu d e th e fu n c tio n o f a " g o -b e tw e e n " :
e s s e n ti a ll y , so m e o n e w ho i s tr u s t e d b y th e d e c is io n m a k e r b u t w ho u n d e r ­
s ta n d s th e te c h n o lo g y of in fo r m a tio n s y s t e m s a n d f o r m a l d a ta a n a ly s is .
The
fu n c tio n of an " i n t e r p r e t e r " of th e te c h n o lo g y i s a ls o n e e d e d ; o n e w ho c o u ld
a l s o a u g m e n t s u c h te c h n o lo g y w ith s u p p le m e n ta ry f o r m s o f a n a ly s is o r su p p ly
of d a ta , b u t w h o se b a s ic r e q u i r e m e n t w o u ld b e th e s e n s itiv ity to u n d e r s ta n d
t h e d iffic u ltie s of c o m m u n ic a tio n in d e a lin g w ith d e c is io n m a k e r s , e s p e c ia lly
w h en th e y la c k s o p h is tic a te d te c h n ic a l tr a in in g .
T h e co n c e p t is o n e o f a n
" in te lle c tu a l t r a d in g p o s t" f o r t r a n s a c tio n s b e tw e e n n e e d an d c a p a b ility .
T h e r e i s s o m e e v id e n c e th a t s u c h s t r u c t u r e s a r e in e m b ry o f o r m in s o m e
c o u n tr ie s , a t s o m e le v e ls of g o v e rn m e n t.
In co m p le x b u r e a u c r a ti c o r g a n i­
z a tio n s , th e tr a d in g - p o s t c o n c e p t ca n b e im p le m e n te d in v is ib ly w ith in an y ,
o r s e v e r a l , e x is tin g fr a m e w o r k s .
In l e s s c o m p le x g o v e r n m e n ts , th e
s t r u c t u r e s w o u ld b e m o r e e v id e n t, p a r t i c u l a r l y n e a r th e p o lic y le v e l of
g o v e rn m e n t w h e re th e y a r e m o s t n e e d e d .
T h e a u th o r w a s p a r t o f s u c h a u n it
in th e S e c r e t a r ia t to th e C a b in e t of th e G o v e rn m e n t of N ova S c o tia b e tw e e n
1969 a n d 1971.
T h is w a s an e n t ir e l y new f o r m a l in s titu tio n w ith in a p r o v in ­
c i a l g o v e rn m e n t in C anada.
A t th e n a tio n a l le v e l in C a n a d a , it c a n b e
o b s e r v e d th a t th e s ta f f in th e P r i m e M in is te r 's o ffic e h a s i n c r e a s e d s u b s ta n ­
t i a l l y in r e c e n t y e a r s ( fro m 20 t o o v e r 100 p e r s o n s ) .
T h e c o n c e p t o f th e tr a d in g p o s t i s o n ly one of s e v e r a l m e th o d s f o r c r e a tin g a
s t r u c t u r e th a t w o u ld allow f o r e ffe c tiv e c o m m u n ic a tio n .
th o u g h t of w ith o u t m u c h e ff o rt.
O th e r s c a n b e
R e g a r d le s s o f th e a c tu a l s t r u c t u r e , h o w e v e r,
th e n e e d f o r i n c r e a s e d c o m m u n ic a tio n is a p p a re n t.
Such c o m m u n ic a tio n w ill
n o t o c c u r w ith o u t e ffo rt; th e e f f o r t s h o u ld , h o w e v e r, b e a te m p o r a r y
p h en o m en o n th a t w ill d e c r e a s e a s th e d e c is io n -m a k in g p r o c e s s e s a n d a g e n c ie s
re s p o n s ib le f o r p r o v is io n an d a n a ly s is of d a ta a d ju s t to new d e m a n d s , an d
a s tr a in in g c h a n g e s th e s k ill s of th e p a r tic ip a n ts .
280
R e v is e d
d e c is io n m a k in g
p ro ce ss
F o rm a l
sp a tia l
m o d e ls
III
R e v is e d
G IS
R e v is e d
d a ta
c o lle c tio n
II
1984
Go-betw een
p ro ce ss
(tra d in g
p o s t)
R e v is e d
G IS
I
1980
F o rm al
s p a tia l
I m o d e ls
F
M
RS
G IS
In c re a se d
s p a tia l d a ta
c o lle c tio n
1974
G IS
F o rm a l
s p a tia l
m o d e ls
1970
P e rio d of in c re a s in g com plexity in concerns of governm ent, in c re a s e in governm ent
in te ra c tio n with th e com m unity and in cre ase d supplies of data. Growing inadequacy
of m ental m odels to provide a satisfac to ry base fo r the decision-m aking p ro c e ss.
Advent of c o m p u ter capability to s to re and m anipulate data.
1945
G o v t.p e rc e p t i ocners n o f
o f G o v t.
F i g. 8 .5 .
D e c is io n m a k in g
p ro ce ss
M e n ta l
m o d e ls
S p a tia l
d a ta
h a n d lin g
D a ta
tion c o l l e c -
I nt e r a c ti on s b e t w e e n d a ta c o lle c tio n , s p a ti a l d a ta h a n d lin g ,
m e n ta l a n d f o r m a l s p a tia l a n a ly s i s , a n d d e c is io n m a k in g ,
o v e r ti m e .
281
T h e lin k a g e s b e tw e e n th e v a r io u s s tr a n d s o f th o u g h t n o te d a b o v e a r e co m p lex
an d v a r y o v e r ti m e .
T h e y h a v e b e e n s u m m a r iz e d in F ig . 8. 5.
F o r th e
p u r p o s e s of d is c u s s io n , th e in c r e a s e s in c o m m u n ic a tio n n e e d e d a r e
r e p r e s e n t e d b y a tr a d in g - p o s t s tr u c t u r e .
T h e d ia g r a m i s c o n c e p tu a l a n d c o n c e n tr a te s on th e c e n tr a l c o n c e r n s of th e
t h e s i s : th o s e of s p a t i a l d a ta h a n d lin g , s p a ti a l d a ta a n a ly s is , a n d d e c is io n
m a k in g in g o v e rn m e n t.
D a te s a r e in d ic a te d on th e r ig h t s id e o f th e d ia g ra m .
T h e tim e s c a l e i s a p p r o x im a te ly li n e a r b e tw e e n 1970 an d 1984, b u t not
r ig o r o u s ly s o .
B e f o re 1945, th e d a ta c o lle c tio n p r o c e s s p ro v id e d d a ta f o r
s p a ti a l d a ta h a n d lin g , w h ic h w a s e x c lu s iv e ly m a n u a l a t th e ti m e .
T h is , in
t u r n , p ro v id e d in p u t to (an d r e c e iv e d d ir e c tio n fro m ) th e e x c lu s iv e ly m e n ta l
m o d e ls , w h ic h h a d in p u t to (and r e c e iv e d d ir e c tio n fro m ) th e d e c is io n - m a k in g
p r o c e s s , w h ic h o p e r a te d in r e s p o n s e to th e g o v e rn m e n t p e r c e p tio n o f th e
c o n c e rn s of g o v e r n m e n t.
F o r a l l th e p r o c e s s e s , th e lin e s of d e v e lo p m e n t co n tin u e ( v e rtic a lly ) f r o m
b e f o r e 1945 to th e to p o f th e d ia g r a m .
T h e s e p r o c e s s e s a r e a l l th u s s t i l l
w ith u s a n d a r e li k e ly to co n tin u e in th e f o r e s e e a b le f u tu r e .
If a p r o c e s s in
th e d ia g r a m u n d e rg o e s s ig n if ic a n t ch a n g e, a new b o x h a s b e e n in s e r t e d on
th e p r o c e s s lin e to in d ic a te th e ch a n g e.
O th e rw is e , th e d ia g r a m is m a in ly
c o n c e r n e d w ith c h a n g e s in th e in te r a c tio n s b e tw e e n th e p r o c e s s e s .
F o r p u r p o s e s of s im p lic ity , th e m a n y v a r i a b le s th a t e n t e r in to th e p r o c e s s
o f p e r c e p tio n of g o v e r n m e n ta l c o n c e rn s a r e n o t show n.
A tte n tio n is f o c u s s e d
on th e r e l a ti o n s h i p s b e tw e e n d a ta c o lle c tio n , h a n d lin g , an d a n a ly s is , and
d e c is io n m a k in g .
T h e p e r io d b e tw e e n 1945 a n d 1970 saw in c r e a s in g c o m p le x ity in th e c o n c e r n s
of g o v e rn m e n t, i n c r e a s e in g o v e rn m e n ta l in t e r a c t io n w ith th e c o m m u n ity , an d
i n c r e a s e d s u p p lie s of d a ta .
A lthough m e n ta l m o d e ls w e r e s t i l l th e p r im a r y
f o r m o f a n a ly s is , th e p o te n tia l c o n trib u tio n of f o r m a l s p a tia l m o d e ls to
d e c is io n m a k in g b e c a m e a p p a re n t.
T h e c o m p u te r b e c a m e a v a ila b le a s a
c a lc u la tin g an d in f o r m a tio n p r o c e s s in g to o l.
D raw in g f r o m m e n ta l m o d e ls an d s u b s e ts of d a ta , d e riv e d f r o m e x is tin g
s t o r e s of d a ta la r g e l y b y m a n u a l p r o c e s s e s , fo r m a l s p a tia l m o d e ls w e r e
282
in tr o d u c e d a s e le m e n ts in th e d e c is io n -m a k in g p r o c e s s .
T h e y m a d e a lim ite d
c o n trib u tio n to m e n ta l m o d e ls an d to d e c is io n m a k in g , an d t h e r e w a s lim ite d
fe e d b a c k .
In th i s p e rio d , te c h n iq u e s f o r h a n d lin g s p a ti a l d a ta w e r e slo w ly
ta k in g a d v a n ta g e of c o m p u te r c a p a b ilitie s a n d d e v e lo p e d in to th e e a r l y
f o r m s of g e o g ra p h ic in fo rm a tio n s y s t e m s (g e o g ra p h ic in fo rm a tio n s y s te m s
in th i s s e n s e in c lu d in g a l l p r o c e s s e s of h a n d lin g s p a ti a l d a ta , m a n u a l an d
c o m p u te r -a id e d ) .
T h e s e m a d e t h e i r f i r s t c o n trib u tio n s to m e n ta l m o d e ls
a n d h e n c e to d e c is io n m a k in g , an d t h e r e w a s li m it e d fe e d b a c k f r o m th e
d e c is io n - m a k in g p r o c e s s .
B etw e en 1970 a n d 1974 th e y m a d e a lim ite d
c o n trib u tio n to f o r m a l s p a ti a l m o d e ls .
T h is s e q u e n c e b r in g s u s to th e
c u r r e n t (1974) s ta t e of a f f a i r s .
T h e in t e r a c t io n s b e tw e e n p r o c e s s e s th a t follow a r e s p e c u la tiv e , b u t r e f l e c t
th e th e m e s id e n tifie d in th e th e s i s .
I n c r e a s e s in th e c o lle c tio n of s p a ti a l d a ta e n c o u ra g e th e d e v e lo p m e n t of
g e o g ra p h ic in f o rm a tio n s y s te m s .
G e o g ra p h ic in f o rm a tio n s y s t e m s te n d to
d e v e lo p on s e p a r a t e l i n e s : s o m e (RS) re s p o n d to th e p ic tu r e - p r o c e s s in g
d e m a n d s of r e m o t e s e n s in g ; s o m e (M) co n tin u e th e tr a d itio n a l fu n c tio n of
p ro v id in g in p u t to m e n ta l m o d e ls ; s o m e (F ), in r e s p o n s e to m u tu a l d e v e lo p ­
m e n t of f o r m a l s p a ti a l a n a ly s is an d d a ta h a n d lin g , a r e p r i m a r i l y u s e d to
p ro v id e in p u t to f o r m a l s p a ti a l m o d e ls .
In th i s l a s t ty p e th e f i r s t e x p e r i­
m e n ts w ith new la n g u a g e s w ill b e m a d e a n d th e te m p o r a l v a r i a b le s w ill
r e c e iv e g r e a t e r a tte n tio n .
D u rin g th i s p e rio d , c o m m u n ic a tio n w ith d e c is io n
m a k e r s (th e g o -b e tw e e n p r o c e s s ) w ill i n c r e a s e , a n d th e u s e of f o r m a l s p a tia l
m o d e ls in d e c is io n m a k in g w ill s lo w ly b e c o m e m o r e fre q u e n t.
F o r m a l s p a t i a l m o d e ls II r e p r e s e n t th e s e to o ls d e v e lo p e d to th e p o in t w h e re
t h e y a r e c o n s id e r a b ly m o r e a lig n e d to th e d e c is io n -m a k in g p r o c e s s .
They
c o n tin u e to m a k e in p u t to m e n ta l m o d e ls an d e n c o u ra g e th e d e v e lo p m e n t
o f th e g o -b e tw e e n p r o c e s s .
T h e y m a k e a n d r e c e iv e in p u t f r o m th e m a in ­
s t r e a m of d e v e lo p m e n t of g e o g ra p h ic in fo r m a tio n s y s t e m s , an d h av e a lim ite d
in flu e n c e in th e c o lle c tio n o f d a ta .
G e o g ra p h ic in fo r m a tio n s y s t e m s , h o w e v e r,
a r e s t i l l m a k in g t h e i r m a jo r c o n trib u tio n to m e n ta l m o d e ls f o r d e c is io n
m a k in g .
283
A t th e le v e l of r e v i s e d g e o g ra p h ic in fo r m a tio n s y s t e m s I, th e s y s te m s w ill
p r o b a b ly h a v e b e n e fitte d s u b s ta n tia lly f r o m d e v e lo p m e n t of d a ta th e o r y and
new s p a ti a l la n g u a g e s .
A m uch g r e a t e r in te g r a tio n of d a ta s o u r c e s an d
f o r m a ts w ill b e p o s s ib le .
Input w ill b e m a d e e i th e r to f o r m a l m o d e ls a n d
th e n c e , b y w ay of m e n ta l m o d e ls , to th e g o -b e tw e e n p r o c e s s , o r d ir e c tly
to m e n ta l m o d e ls a n d th e g o -b e tw e e n p r o c e s s .
M ost im p o r ta n tly , th e r e
w ill b e a s tr o n g f e e d b a c k to th e d e s ig n of in fo rm a tio n s y s t e m s f r o m th e
g o -b e tw e e n p r o c e s s .
T h e fe e d b a c k to th e d a ta c o lle c tio n a g e n c ie s w ill s t i l l
b e lim ite d .
A f te r th e n e x t d e c a d e , it is a s s u m e d th a t m a n y of th e c o m m u n ic a tio n a s p e c t s
o f th e g o -b e tw e e n p r o c e s s w ill h a v e b e e n in c o r p o r a te d in to w h a t w ill th e n
b e s ta n d a r d f o r m s of d e c is io n m a k in g .
T h is w ill in v o lv e c o m m u n ic a tio n
w ith a t h i r d g e n e ra tio n of s p a tia l m o d e ls in t e g r a t e d in to th e d e c is io n
p r o c e s s , a n d w ith g e o g ra p h ic in fo rm a tio n s y s t e m s s i m i l a r l y alig n e d .
The
m a in r e s u l t of th e s e d e v e lo p m e n ts w ill b e s tr o n g fe e d b a c k to th e p r o c e s s e s
o f d a ta c o lle c tio n a n d a r e v i s e d a n d s e le c tiv e p r o c e s s of d a ta c o lle c tio n .
I t i s e m p h a s iz e d a g a in th a t th e s e in t e r a c t io n s a r e s p e c u la tiv e .
Som e
c o m m e n ts on s o m e of th e tim in g s e n v is a g e d m ig h t, h o w e v e r, b e w o rth w h ile .
T h e r e l a ti v e ly slo w im p le m e n ta tio n of th e g o -b e tw e e n p r o c e s s i s b a s e d o n a
view of th e in h e r e n t i n e r t i a of g o v e rn m e n t in s titu tio n s a n d th e lik e lih o o d th a t
t h e r e w ill h a v e to b e d e m o n s tra b ly b e t t e r f o r m a l m o d e ls a n d g e o g ra p h ic
in fo rm a tio n s y s t e m s b e f o r e th e n e e d f o r i n c r e a s e d c o m m u n ic a tio n s w ill b e
s ub s ta n tia te d .
T h e p r e d ic tio n th a t d e v e lo p m e n t of d e c is io n - o r ie n te d
g e o g ra p h ic in fo rm a tio n s y s te m s w ill b e la t e ( c i r c a 1983) is b a s e d on th e la c k
o f c u r r e n t r e s e a r c h in th e u n d e rp in n in g s of th e o r y a n d la n g u a g e of th e p r o c e s s .
T h e d e v e lo p m e n t of v a s tly i n c r e a s e d co m p u tin g p o w e r w o u ld a m e lio r a te th e
s itu a tio n , b u t w o u ld n o t n e c e s s a r i l y p r o v id e e ffic ie n t s o lu tio n s to th e u n d e r ­
ly in g p r o b le m s .
T h e d e v e lo p m e n t of a s tr o n g fe e d b a c k lo o p to th e tr a d itio n a l
p r o c e s s of d a ta c o lle c tio n m u s t a w a it, and fo llo w , th e s o lid e s ta b lis h m e n t
of th e o th e r p r o c e s s e s .
N o e f fe c tiv e p e r s u a s io n c a n b e b r o u g h t to b e a r
w h ile m a n ip u la tio n p r o c e s s e s , f o r m a l s p a tia l a n a ly s is , a n d d e c is io n
p r o c e s s e s th e m s e lv e s a r e ra p id ly ev o lv in g .
1. T h e d e v e lo p m e n t of l a r g e - s c a l e p a r a l l e l p r o c e s s in g c o m p u te r s s i m i l a r
to th e e x p e rim e n ta l IL L IA C IV a t th e U n iv e r s ity of Illin o is , o r th e c a p a b ility
of d ev e lo p in g m u ltip le - c p u in t e r f a c e s , w ould allow tw o -d im e n s io n a l d a ta to
b e h a n d le d w ith m o r e f a c ility th a n i s c u r r e n t ly p o s s ib le . T h e r e i s no
e v id e n c e , h o w e v e r, th a t s u c h d e v e lo p m e n ts in c o m p u te r s c a n b e a n tic ip a te d
in th e n e a r f u tu r e .
284
T h e d ia g r a m r e p r e s e n t s o n e v e r s io n o f m a n y p o s s ib le p a tte r n s o f in te r a c tio n .
P e r h a p s i t s m a in fu n c tio n i s to s t r e s s th a t s u c h in te r a c tio n is e s s e n ti a l if
r a t io n a l d e v e lo p m e n t of s t o r e s of in fo rm a tio n , g e o g ra p h ic in fo rm a tio n
s y s t e m s , f o r m a l s p a ti a l m o d e ls , a n d d e c is io n m a k in g is to go f o r w a r d .
SUMMARY
T h e s e tw o f in a l c h a p te r s of th e th e s i s h a v e b r ie f ly e x a m in e d th e i n t e r ­
-r e l a ti o n s h i p s b e tw e e n g e o g ra p h ic in fo rm a tio n s y s t e m s , f o r m a l s p a tia l
a n a ly s is , a n d d e c is io n m a k in g in g o v e rn m e n t.
In C h a p te r 7, th e c h a r a c t e r i s t i c s of f o r m a l s p a ti a l a n a ly s is a n d th e n
g o v e rn m e n ta l d e c is io n m a k in g w e r e d is c u s s e d on th e b a s i s o f t h e i r n e e d s
f o r s p a ti a l d a ta h a n d lin g .
T h e v a r io u s c a te g o r ie s of g e o g ra p h ic in fo rm a tio n
s y s t e m id e n tif ie d in th e p re v io u s c h a p te r s w e re c o n s id e re d in t e r m s o f th e
c o n tr ib u tio n th e y m a k e to th e s e p r o c e s s e s .
T h e v a ry in g c o n trib u tio n s o f
th e d if fe re n t ty p e s o f s y s t e m w e r e m a d e a p p a re n t an d th e in s titu tio n a l b a s i s
o f t h e i r d e v e lo p m e n t w a s d e m o n s tra te d .
T h e o v e r a l l v a lu e of g e o g ra p h ic
in fo rm a tio n s y s t e m s w a s e x a m in e d .
In C h a p te r 8, li n e s of f u tu r e d e v e lo p m e n t w e r e p o s tu la te d , a s s u m in g p r e s e n t
an d f u tu r e c o m p u tin g c a p a b ilitie s .
T h e n , on th e b a s i s th a t g e o g ra p h ic i n f o r ­
m a tio n s y s t e m s a r e n o t s im p ly p r o c e s s in g to o ls b u t th a t t h e i r u s e f u ln e s s
i s in h e r e n tly a lig n e d to t h e i r b r o a d e r fu n c tio n a s s t o r e s of in fo rm a tio n ,
t h e i r d e v e lo p m e n t w a s e x a m in e d w ith in th e b r o a d e r co n tex t.
Som e o f th e
g e n e ra l c o m p le x itie s in th e r e la tio n s h ip s b e tw e e n s p a tia l th e o r y , s t o r e s
o f s p a ti a l in fo r m a tio n an d th e d e c is io n p r o c e s s in g o v e rn m e n t in s titu tio n s
w e r e n o ted .
T h e f u tu r e d e v e lo p m e n t of in t e r a c t io n b e tw e e n s p a ti a l d a ta an d f o r m a l s p a ti a l
a n a ly s is w ith in th e d is c ip lin e of g e o g ra p h y w a s p o s tu la te d .
It w a s s e e n th a t
e a s y m a n ip u la tio n of p a r t ic u l a r s e t s of m ic r o d a ta p ro v id e s s c o p e f o r i m p r o v e ­
m e n ts in th e s p e e d a n d p r e c i s io n w ith w h ic h h y p o th e se s a r e te s te d .
T h is
f a c ility , m o r e th a n th e v o lu m e of d a ta it s e lf , w ill p ro v id e th e m a in c o n t r i ­
b u tio n of g e o g ra p h ic in fo r m a tio n s y s t e m s to th e d is c ip lin e o f g e o g ra p h y ,
e s p e c i a ll y w h e n d ir e c te d to w a r d p ro b le m s of d y n am ic a n a ly s is a n d s u p p o r te d
b y th e a c tiv e d e v e lo p m e n t of s u ita b le m u ltid im e n s io n a l la n g u a g e s .
The
285
fu tu r e d e v e lo p m e n t o f d e c is io n m a k in g in r e s p o n s e to d e v e lo p m e n ts in
g e o g ra p h ic in f o rm a tio n s y s t e m s an d s p a ti a l a n a ly s is w a s a ls o c o n s id e r e d
a n d s o m e li n e s of d e v e lo p m e n t w e r e p o s tu la te d .
I t w as m a d e c l e a r th a t
th e d e v e lo p m e n t of g e o g r a p h ic in fo rm a tio n s y s te m s a s d e s c r ib e d in th is
th e s i s m u s t b e v ie w e d n o t a s a n is o la te d p r o c e s s , b u t a s a n in t e g r a l p a r t
of a v e r y l a r g e s t r u c t u r e of d a ta g a th e rin g , d a ta a n a ly s is , a n d d e c is io n
m a k in g .
T h e t h e o r e t i c a l u n d e rp in n in g s of th e s t r u c t u r e , in p a r t ic u l a r
th e o r y ap p ly in g to d a ta , la n g u a g e s , s p a tia l a n a ly s is , o rg a n iz a tio n , an d
d e c is io n s a r e n o t s tr o n g .
I t is s u g g e s te d th a t r a t io n a l d e v e lo p m e n t of
b o th th e t h e o r e ti c a l b a s i s a n d p r a g m a tic a p p lic a tio n w ill b e n e fit f r o m
e x p lo ra tio n a n d r e c o g n itio n of t h e i r in te rd e p e n d e n c e , an d f r o m a s u b s ta n tia l
i n c r e a s e in in t e r a c t io n b e tw e e n th e te c h n iq u e s of d a ta g a th e r in g , d a ta
h a n d lin g , d a ta a n l a y s is , a n d d e c is io n m a king.
286
R EFERENCES
A le x a n d e r, C. 1964. N o te s on th e s y n th e s is of fo r m .
P r e s s , C a m b rid g e , M a ss.
H a r v a r d U n iv e r s ity
-. 1967. T h e c ity a s a m e c h a n is m f o r s u s ta in in g h u m a n c o n ta c t.
C h a tp e r 4 in E w a ld , W. R . J r . , E n v iro n m e n t f o r m an : T h e n ex t
f ifty y e a r s . In d ia n a U n iv e r s ity P r e s s , B lo o m in g to n , Ind.
- a n d C h e rm a y e ff, S. 1966. C o m m u n ity an d p riv a c y .
H a rm o n d s w o rth , M id d le se x .
P e n g u in B o o k s,
A lfr e d s s o n , B. , S a lo m o n ss o n , O. a n d S e la n d e r, K . 1970. F R IS A :l. A
s p a ti a l in fo r m a tio n s y s t e m - A p ilo t s tu d y . In tro d u c tio n . C e n tr a l
B o a rd f o r R e a l E s ta te D a ta , S u n d b y b erg , Sw eden.
A lm e n d in g e r, V. 1973. U rb a n D e c is io n S y s te m s I n c . , L o s A n g e le s, C a lif.
P e r s o n a l c o m m u n ic a tio n .
A lo n s o , W. 1964. L o c a tio n a n d la n d u s e : T o w a rd a g e n e r a l t h e o r y of la n d
r e n t . H a r v a r d U n iv e r s ity P r e s s , C a m b rid g e , M a ss.
A m id o n , E . L . 1964. A c o m p u te r o r ie n te d s y s t e m f o r a s s e m b lin g an d
d is p la y in g la n d m a n a g e m e n t in fo rm a tio n . R e s e a rc h p a p e r P S W -17.
U n ite d S ta te s D e p a r tm e n t of A g r ic u l tu r e , F o r e s t S e r v ic e , B e r k e le y ,
C a lif.
-. 1966. A n a lp h a n u m e r ic m a p in fo r m a tio n a s s e m b ly a n d d is p la y
s y s t e m f o r a l a r g e c o m p u te r.
R e s e a r c h p a p e r P S W -3 8 . U n ite d S ta te s
D e p a rtm e n t of A g r ic u ltu r e , F o r e s t S e rv ic e , B e rk e le y , C a lif,
-. 1972. V IEW IT. P a g e s 9 4 3 -9 4 6 in T o m lin s o n , R. F . , ed . ,
G e o g ra p h ic a l d a ta h a n d lin g . IGU
C o m m is s io n on G e o g ra p h ic a l D ata
S e n s in g an d P r o c e s s in g , O tta w a , O nt.
A m s te r d a m , R . 1968. G IST: A g e o g ra p h ic in f o rm a tio n s y s t e m f o r New Y o rk
Cit y - P r e l i m i n a r y d e s ig n . C ity of New Y o rk , O ffice of th e M ay o r,
O ffice of A d m in is tr a tio n , New Y o rk , N. Y.
-. 1969. T h e c o n c e p t of d a ta n e tw o rk an d th e d e v e lo p m e n t o f GIST.
C ity o f New Y o rk ,
O ffice of th e M a y o r, O ffice of A d m in is tr a tio n ,
New Y o rk , N. Y.
A p p e l, A . , D an k o w sk i, T . P . a n d D o u g h e rty , R . L. 1968. A s p e c ts o f d is p la y
te c h n o lo g y . IB M
S y s te m s J o u r n a l 7 (3 an d 4 ) :176-1 8 7 .
A r m s , S. 1967. M aps a n d c o m p u te r s : L o c a tio n a l in fo rm a tio n p r o c e s s in g
f o r p la n n in g an d g o v e rn m e n t. C o lu m b ia R eg io n A s s o c ia tio n o f G o v e rn
m e n ts , M e tro p o lita n P la n n in g C o m m is s io n , P o r tla n d , O r e .
(O ut o f p r i n t . )
- .
1968.
M A P /M O D E L s y s te m : T e c h n ic a l co n c e p ts a n d p r o g r a m
d e s c r i p tio n s . C o lu m b ia R e g io n A s s o c ia tio n of G o v e rn m e n ts , P o r tla n d ,
O re.
- .
1969. M A P /M O D E L s y s te m : D a ta e n t r y an d r e t r i e v a l . B u re a u of
G o v e rn m e n ta l R e s e a r c h a n d S e r v ic e , U n iv e rs ity of O reg o n , E u g e n e, O re .
287
A r m s , S. 1970. M A P /M O D E L s y s te m : S y s te m d e s c r ip tio n a n d u s e r 's
g u id e . B u re a u of G o v e rn m e n ta l R e s e a r c h and S e rv ic e , U n iv e r s ity of
O re g o n , E u g e n e , O re .
A te l ie r P a r i s i e n d 'U r b a n is m e . 1972. M ap of P a r i s . P a g e s 9 3 9 -9 4 2 in
T o m lin s o n , R . F . , ed. , G e o g ra p h ic a l d a ta h an d lin g . IGU C o m m is sio n
o n G e o g ra p h ic a l D a ta S e n s in g and P r o c e s s in g , O tta w a , O nt.
A u m en , W. 1970. A new m a p f o r m : N u m b e rs .
C a r to g r a p h y 10 :8 0 -8 4 .
B a lc h in , W. V. G. a n d C o le m a n , A . M.
T h e C a r to g r a p h e r 4(2): 120-127.
1967.
I n te r n a tio n a l Y e a rb o o k of
C a r to g ra p h y a n d c o m p u te rs .
B a rb , C. E . 1968. S tr e e t a d d r e s s c o n v e rs io n s y s te m : A n a u to m a te d , g e o ­
c o d in g s y s t e m f o r u r b a n a n a ly s is . P a p e r s f r o m th e 6 th A n n u al
C o n fe re n c e of th e U rb a n a n d R e g io n a l In fo rm a tio n S y s te m s A s s o c ia tio n ,
C la y to n , M is s.
B a r r a c lo u g h , R . E . 1972. N a tio n a l g e o c o d in g s y s te m . In G eo co d in g '7 2 .
P a p e r s of th e G e o g ra p h ic B a s e F ile S p e c ia l I n t e r e s t G ro u p , 10th
A n n u al C o n fe re n c e , U rb a n a n d R e g io n a l In fo rm a tio n S y s te m s
A s s o c ia tio n , S an F r a n c i s c o , C alif.
B a r r e t t , J . 1973. D e p a rtm e n t o f D a ta S y s te m s , M e tro p o lita n W a sh in g to n
C o u n c il of G o v e rn m e n ts , W a sh in g to n , D. C. 20035. P e r s o n a l
c o m m u n ic a tio n .
B a tty , M. 1970. S p a tia l th e o r y a n d in fo r m a tio n s y s t e m s . W o rk in g p a p e r
M J S R U - W P - 3 1 0 . U rb a n
S y s te m s R e s e a r c h U n it, U n iv e r s ity o f R ea d in g ,
R e a d in g , E n g lan d .
B e c k e r , P . C . 1971. T h e r i s e an d f a l l of th e m a s t e r p a r c e l f ile . P r o c e e d in g s
o f th e 9th A n n u al C o n fe re n c e of th e U rb a n an d R e g io n a l I n fo rm a tio n
S y ste m s A s s o c ia tio n , New O r le a n s , L a.
B e n g ts s o n , B. -E . a n d N o rd b e c k , S. 1964. C o n s tru c tio n o f is a r i t h m s and
is a r i th m i c m a p s b y c o m p u te r s . N o r d is k T i d s k r i f t f o r I n f o r m a tio n s B e h a n d lin g 4 (2 ):8 7 -1 0 5 .
B e r r y , B . J . L . 1961. C ity s iz e d is tr ib u tio n s a n d e c o n o m ic d e v e lo p m e n t.
E c o n o m ic D e v e lo p m e n t a n d C u ltu ra l E x c h an g e 9 (4 ):5 7 3 -5 8 8 .
- .
1967. G e o g ra p h y of m a r k e t c e n te r s an d r e t a i l d is tr ib u tio n .
P r e n ti c e - H a ll , E n g -lew o o d C liff s , N .J .
an d G a r ris o n ,W .L . 1958. A lte r n a te e x p la n a tio n s o r u r b a n r a n k - s iz e r e l a
tio n s h ip s . A n n a ls of th e
A -s s o c ia tio n of A m e r ic a n G e o g r a p h e r s 4 8 :8 3 -9 1 .
a n d M a rb le , D. F . , e d s . 1968. S p a tia l a n a ly s is ; A r e a d e r in s t a t i s ­
t i c a l g e o g ra p h y . P r e n ti c e - H a ll , E n g lew o o d C liffs , N .J .
B e r t in , J . 1970. L a c a rto g r a p h ie d a n s " L a c iv ilis a tio n d e 1' in f o r m a ti q u e. "
I n te r n a tio n a l Y e a rb o o k o f C a r to g r a p h y 10 :8 5 -9 4 .
B e ta k , J . F . 1974a. T h e c o n c e p tu a l lo c u s of a tw o -d im e n s io n a l la n g u a g e :
Som e im p lic a tio n s f o r h u m a n r e s p o n s e s to tw o -d im e n s io n a l d is p la y s .
D e p a rtm e n t of G eo g ra p h y , M c M a s te r U n iv e r s ity , H a m ilto n , O nt.
M im e o g rap h .
288
B e ta k , J . F . 1974b. S y n ta c tic a n d s u b je c tiv e c o m p le x ity : A s im p le t e s t of
a tw o -d im e n s io n a l la n g u a g e m o d e l. D e p a rtm e n t of G eo g rap h y ,
M c M a s te r U n iv e rs ity , H a m ilto n , O nt. M im e o g rap h .
B ic k m o re , D. P . 1966. E x p e r im e n ta l c a rto g r a p h y p ro je c t. I n te r im r e p o r t
to th e N a tu ra l E n v iro n m e n t R e s e a rc h C o u n cil. R o y a l C o lle g e o f A r t,
L ondon, E n g lan d .
-
.
1971. A u to m a tic c a rto g r a p h y a n d p la n n in g .
L o n d o n , E n g lan d .
A r c h ite c tu r a l P r e s s ,
B o eh m , B . W. 1967. T a b u la r r e p r e s e n t a ti o n s of m u ltiv a r ia te fu n c tio n s w ith a p p lic a tio n s to to p o g ra p h ic m o d e lin g . P ro c e e d in g s of th e 22nd
N a tio n a l C o n fe re n c e , A s s o c ia tio n of C o m p u tin g M ach in ery , p p . 4 0 3 -4 1 5 .
B o eh n e , R . C . 1967. D ig ita l s im u la tio n of e n v iro n m e n ta l lim ita tio n s o f i n t e r v is ib ility . In H o llin g d a le , S. H. , ed . , D ig ita l s im u la tio n in o p e r a tio n a l
r e s e a r c h . A m e r ic a n E l s e v ie r P u b lis h in g C o ., New Y o rk , N. Y .
B o ein g C o m p u te r S e r v ic e s , In c . 1972a. N a tu r a l r e s o u r c e in f o rm a tio n s y s te m ,
v o lu m e I: O v e ra ll d e s c r ip tio n . B o e in g C o m p u te r S e r v ic e s , I n c . ,
S e a ttle , W ash.
-
.
1972b. N a tu r a l r e s o u r c e in fo rm a tio n s y s te m : D e sig n a n a ly s is .
B o e in g C o m p u te r S e r v ic e s , In c. , S e a ttle , W ash.
B o g u e, D. J . e t a l. 1957. S u b re g io n a l m ig r a tio n in th e U n ite d S ta te s : 1 9 3 5 4 0 , v o lu m e 1. S c rip p s F o u n d a tio n S tu d ie s in P o p u la tio n D is tr ib u tio n ,
O x fo rd , O hio.
B o r c h e r t , J . R . 1969. M in n e s o ta la k e s h o r e d e v e lo p m e n t s tu d y . D e p a rtm e n t
o f G e o g ra p h y , U n iv e r s ity of M in n e s o ta , M in n e a p o lis, M inn.
B o y le , A . R . 1970a. C o m p u te r a id e d c o m p ila tio n . P a p e r p r e s e n te d a t th e
9th A n n u al H y d ro g ra p h ic C o n fe re n c e . C a n a d ia n H y d ro g ra p h ic S e r v ic e ,
D e p a rtm e n t of E n e rg y , M in es a n d R e s o u r c e s , O tta w a , O nt.
- .
1970b. A u to m a tio n in h y d r o g ra p h ic c h a rtin g .
S u rv e y o r 2 4 (5 ):5 1 9 -5 3 7 .
- .
1971. C o m p u te r a id e d m a p c o m p ila tio n s . N a tio n a l R e s e a r c h C o u n cil
2nd S e m in a r, R e p o rt on
M an / M ach in e C o m m u n ic a tio n . N a tio n a l
R e s e a r c h C o u n c il, O tta w a , Ont.
- .
1972.
c h a rts .
B ray , J .
T h e C an a d ian
A c h a r a c t e r re c o g n itio n d e v ic e f o r so u n d in g s o n n a v ig a tio n a l
S u rv e y in g a n d M apping 3 2 (l):2 7 -3 5 .
1970.
D e c isio n in g o v e rn m e n t.
V ic to r G o lla n cz, L o ndon, E n g lan d .
B ro a d b e n t, T . A. 1969. S om e te c h n iq u e s f o r r e g io n a l e c o n o m ic a n a ly s is .
C E S -W P -2 3 . C e n tre f o r E n v iro n m e n ta l S tu d ie s, London, E n g lan d .
B ro w n , T . 1970. A u to m a tic lin e fo llo w in g .
S a s k a tc h e w a n , S a sk a to o n , S ask.
M. Sc. T h e s is ,
U n iv e r s ity of
B r u e r , P . M. L . 1967. T h e E r i e p r o je c t n a r r a t i v e . P a p e r p r e s e n te d at
U n iv e r s ity of W e s te r n O n ta rio , D e p a rtm e n t of G eo g rap h y C o n fe re n c e
on th e E r i e P r o je c t. U n iv e rs ity of W e s te r n O n ta rio , L o ndon, O nt.
289
B u rc h , J . G. J r . a n d S t r a t e r , F . 1974. In fo r m a tio n s y s te m s : T h e o ry and
p r a c t ic e . H a m ilto n , S an ta B a r b a r a , C a lif.
B u r g e s s , E. W . 1925. T h e g ro w th of th e c ity . In P a r k , R . E. and B u r g e s s ,
E . W ., e d s . , T h e c ity . C h ic ag o U n iv e r s ity P r e s s , C h ic a g o , I ll.
B u rto n , I. 1963. T h e q u a n tita tiv e re v o lu tio n a n d th e o r e ti c a l g eo g rap h y .
T h e C a n a d ia n G e o g ra p h e r 7(4): 151-162.
C a lk in s , H. W. 1967. O tta w a s t r e e t a d d r e s s c o n v e rs io n s y s te m .
R e s e a r c h R e c o r d 1 94:96-102.
H ighw ay
-. 1973. U rb a n S y ste m s L a b o r a to r y , U n iv e r s ity of W a sh in g to n ,
S e a ttle , W a sh . P e r s o n a l c o m m u n ic a tio n .
,- R o b e r ts o n , J . L . a n d W ie rm a n , S. S. G. 1973. T h e le g is la tiv e m a n
d a te f o r s ta t e la n d in f o rm a tio n s y s t e m s . P a p e r s f r o m th e l i t h A n n u al
C o n fe re n c e o f th e U rb a n a n d R e g io n a l I n f o rm a tio n S y s te m s A s s o c ia tio n ,
A tla n tic C ity , Ga.
C a rn a p , R . 1958. I n tro d u c tio n to s y m b o lic la n g u a g e a n d i t s a p p lic a tio n s .
New Y o rk , N. Y.
C a r r o t h e r s , G. A. P . 1956. A n h i s t o r i c a l r e v ie w of th e g r a v ity an d p o te n tia l
c o n c e p ts of h u m a n in te r a c tio n . J o u r n a l o f th e A m e r ic a n I n s titu te of
P l a n n e r s 2 2 :9 4 -1 0 2 .
C a s s e tt i, F . a n d S e m p le , R . K. 1968. A m e th o d f o r s te p w is e s e p a r a tio n
of s p a ti a l tr e n d s . D is c u s s io n P a p e r 2, M ic h ig a n I n te r - U n iv e r s i ty
C o m m u n ity o f M a th e m a tic a l G e o g r a p h e r s . D e p a rtm e n t o f G eo g rap h y ,
U n iv e r s ity of M ich ig an , A nn A r b o r , M ich.
C a t e r , E . A. 1970. I n fo rm a tio n n e e d s f o r p la n n e r s : A s u r v e y . W o rk in g
p a p e r U S R U -W P -4 . U rb a n S y ste m s R e s e a r c h U n it, U n iv e r s ity of
R e a d in g , R e a d in g , E n g lan d .
C h ap in , F . S. J r . a n d W e is s , S. F . 1962a. F a c t o r s in flu e n c in g la n d
d e v e lo p m e n t. In s titu te f o r R e s e a rc h in S o c ia l S c ie n c e s , U n iv e r s ity
of N o rth C a r o lin a , C h a p e l H ill, N. C.
,- e d s .
N. Y.
1962b.
U rb a n g ro w th d y n a m ic s .
J o h n W ile y & S o n s, New Y o rk ,
C h e s h ir e , A . 1970. S ta tis tic s f o r p la n n in g . W o rk in g p a p e r s U S R U -W P -5
a n d U S R U -W P -6 . U rb a n S y s te m s R e s e a r c h U n it, U n iv e r s ity of
R e a d in g , R e a d in g , E n g lan d .
C h is h o lm , M. 1961. R u r a l s e ttle m e n t an d la n d u s e .
L i b r a r y , L o n d o n , E n g lan d .
H u tc h in so n U n iv e r s ity
C h o rle y , R . J . a n d H a g g e tt, P . 1965. T r e n d - s u r f a c e m a p p in g in g e o g ra p h ic a l
r e s e a r c h . T r a n s a c tio n s of th e In s titu te o f B r i t i s h G e o g r a p h e r s 37:47-67.
-, e d s .
1967.
M o d els in g e o g rap h y .
M eth u e n & C o . , L o ndon, E n g lan d .
C h r i s t a l l e r , W. 1935. D ie z e n tr a le n O rte in S u d d e u tsc h la n d . G. F is c h e r
V e rla g , J e n a . T h e c e n tr a l p la c e s of s o u th e r n G e rm a n y . T r a n s la te d
b y C. B a s k in g , 1966. P r e n ti c e - H a ll , E n g lew o o d C liffs , N .Y .
290
C ity of V a n c o u v e r. 1965. A n in fo rm a tio n r e t r i e v a l s y s t e m f o r u r b a n a r e a s .
C ity E n g in e e r in g D e p a rtm e n t, V a n c o u v e r, B. C.
C la r k , R . A. 1970. C o m p u te r g e n e ra te d p r o f ile m a p s . P r o c e e d in g s of th e
S e m ia n n u a l C o n v en tio n of th e A m e r ic a n S o c ie ty of P h o to g r a m m e tr y ,
D e n v e r, C olo.
C le la n d , D. S. an d K ing, W . M. R . 1969. S y s te m s , o r g a n iz a tio n s , a n a ly s is ,
m a n a g e m e n t: A b o o k of r e a d in g s . M c G ra w -H ill, New Y o rk , N. Y.
C liff, A. D. an d O rd , J . K.
L o n d o n , E n g lan d .
1973.
S p a tia l a u to c o r r e la tio n .
P io n L t d . ,
C o le , J . P . a n d K ing, C. A. M. 1968. Q u a n tita tiv e g eo g rap h y : T e c h n iq u e s
an d th e o r ie s in g e o g ra p h y . J o h n W ile y & S ons, L o ndon, E n g lan d .
C o m p re h e n s iv e P la n n in g O rg a n iz a tio n . 1971. P r o p o s e d in f o rm a tio n s y s t e m
f o r p la n n in g , v o lu m e 1. C o m p r e h e n s iv e P la n n in g O r g a n iz a tio n
J o b 0050. C o m p re h e n s iv e P la n n in g O rg a n iz a tio n , San D iego C o unty,
S an D iego, C a lif.
C o o k e, D. 1973. U rb a n D a ta P r o c e s s i n g C o m pany, C a m b rid g e , M a s s.
P e r s o n a l c o m m u n ic a tio n .
C o o m b e r, N .H . a n d B is w a s , A. K . 1972. E v a lu a tio n of e n v iro n m e n ta l
in ta n g ib le s : R eview of te c h n iq u e s .
E n v iro n m e n t C an a d a, E c o lo g ic a l
S y s te m s B ra n c h , R e s e a r c h C o o rd in a tio n D ir e c t o r a te ,
P o lic y P la n n in g
a n d R e s e a r c h S e rv ic e , O tta w a , O nt.
C o o m b s , C. H.
1964.
A th e o r y of d a ta .
J o h n W iley & S ons, New Y o rk , N. Y.
C o p p o ck , J . T . 1962. E l e c t ro n i c d a ta p r o c e s s in g in g e o g ra p h ic a l r e s e a r c h .
T h e P r o f e s s i o n a l G e- o g r a p h e r 14(4): 1 -4 .
a n d J o h n s o n , J . H. 1962. M e a s u r e m e n t in h u m a n g eo g rap h y .
E c o n o m ic G e o g rap h y 38(2): 1 3 0 -137.
C o rb e tt, J . a n d F a r n s w o r t h , G. 1971. T h e o r e tic a l b a s is o f d u a l in d e p en d en t
m a p en c o d in g (D IM E). P a p e r s f r o m th e 9th A nnual C o n fe re n c e of
th e U rb a n an d R e g io n a l In f o rm a tio n S y s te m s A s s o c ia tio n , New O r le a n s ,
La.
C o v e n try C ity C o u n cil. 1970. P o in t d a ta s y s te m . R e p o r t, M a rc h 1970.
D e p a rtm e n t of A r c h it e c tu r e a n d P la n n in g and C ity T r e a s u r e r s
D e p a rtm e n t, C o v e n try C ity C o u n c il, C o v e n try , E ngland;
C r ip p s , E . L. 1970. A c o m p a r a tiv e s tu d y of in f o rm a tio n s y s te m s f o r u rb a n
an d re g io n a l p la n n in g , 1: S c a n d in a v ia . W o rk in g p a p e r U S R U -W P -7 /0 .
U rb a n S y s te m s R e s e a r c h U n it, U n iv e r s ity of R ea d in g , R e a d in g , E n g lan d .
D a c e y , M. F . 1964. In d iv id u a tio n in s u b s ta n c e and s p a c e - tim e la n g u a g e s
an d C a r n a p 's c la s s i f ic a t io n of
r u le s of d e s ig n a tio n and p o s itio n a l
c o o rd in a te s . M em o, GSI (m fd) 1 a n d 2. R e g io n a l
S cien ce D e p a rtm e n t,
U n iv e rs ity of P e n n s y lv a n ia , P h ila d e lp h ia , P a .
-. 1965a. T h e g e o m e tr y of c e n t r a l p la c e th e o ry .
S e r ie s B 4 7 :1 1 1 -1 2 4 .
G e o g ra fis k a A n n a le r
291
D a c e y , M. F . 1965b. Som e o b s e rv a tio n s , on a tw o -d im e n s io n a l la n g u a g e .
T e c h n ic a l R e p o rt 7 of O ffice o f N a v a l R e s e a r c h T a s k No. 3 8 9 -1 4 2 ,
C o n tr a c t NONR 1228(35). D e p a rtm e n t of G eo g rap h y , N o r th w e s te rn
U n iv e r s ity , E- v a n sto n , I l l .
a n d M a rb le , D. F . 1965.
o f g e o g ra p h ic i n f o rm a tio n
N a v a l R e s e a r c h T a s k No.
D e p a r tm e n t of G eo g rap h y ,
Som e c o m m e n ts on c e r t a in te c h n ic a l a s p e c t s
s y s te m s . T e c h n ic a l R e p o rt 2 o f O ffice of
3 8 9 -1 4 2 , C o n tra c t NONR 1228(35).
N o r th w e s te r n U n iv e rs ity , E v a n sto n , 111.
D a n g e rm o n d , J . 1971. P o ly g o n in fo rm a tio n o v e r la y s y s te m . C o m p re h e n s iv e
P la n n in g O rg a n iz a tio n , San D iego C ounty, San D iego, C alif.
-
. 1973. T e c h n ic a l a l te r n a t iv e s f o r g e o g ra p h ic a l in fo rm a tio n s y s t e m s a t
s t a t e /r e g io n a l le v e l. P a p e r s f r o m th e 11th A nnual C o n fe re n c e of th e
U rb a n a n d R e g io n a l In fo rm a tio n S y s te m s A s s o c ia tio n , A tla n tic C ity , Ga.
D ayhoff, M. O. 1963. A c o m p u te r m a p p r o g r a m f o r X - r a y c r y s ta llo g r a p h y .
C o m m u n ic a tio n s of th e A s s o c ia tio n f o r C o m p u tin g M a c h in e ry 6(10):
6 2 0 -6 2 2 .
D e la w a r e C o u n ty P la n n in g C o m m is sio n . 1970. D e la w a re C o u n ty P la n n in g
C o m m is s io n in fo rm a tio n s y s te m . D e la w a re C ounty P la n n in g
C o m m is s io n , M ed ia, P a .
D e p a r tm e n t of th e E n v iro n m e n t, U .K . 1973. M anual on p o in t r e f e r e n c in g
p r o p e r t i e s an d p a r c e ls of la n d . T e c h n iq u e s f o r p la n n in g . H e r
M a je s t y 's S ta tio n e r y O ffic e , L ondon, E n g lan d .
D e u ts c h , K. W. 1966. T h e n e r v e s of g o v e rn m e n t: M odels o f p o litic a l
c o m m u n ic a tio n a n d c o n tro l.
New Y o rk , N. Y.
D ie llo , J . 1970. T h e e v o lu tio n o f a u to m a tio n in c a r to g r a p h y a t R o m e A ir
D e v e lo p m e n t C e n te r . A ir F o r c e S y s te m s C o m m an d , G r if f is s A ir
F o r c e B a s e , - R o m e , N. Y.
, K ir k , K. an d C a lla n d e r, J . 1969. T h e d e v e lo p m e n t o f a n a u to m a te d
c a r t o g r a p h ic s y s te m . T h e C a rto g ra p h ic J o u r n a l 6(1) :9 -17.
D odd, G. G. 1969. E le m e n ts of d a ta m a n a g e m e n t s y s te m s .
S u rv e y s 1:1 1 7 -1 3 3 .
C o m p u tin g
D ow d, R . 1973. D e p a r tm e n t of H o s p ita ls , L o s A n g ele s C o unty, L o s A n g e le s ,
C a lif. P e r s o n a l c o m m u n ic a tio n .
D ow ns, R . M. an d S te a , D . , e d s . 1973. Im a g e an d e n v iro n m e n t:
m a p p in g a n d s p a ti a l b e h a v io r . Aldine., C h ic ag o , I ll.
C o g n itiv e
D udnik, E . E . 1972. SECTIO N : P a g e s 928-931 in T o m lin s o n , R . F . , e d . ,
G e o g r a p h ic a l d a ta h a n d lin g . IGU C o m m is s io n on G e o g ra p h ic a l
D a ta S e n s in g a n d P r o c e s s in g , O tta w a , O nt.
D u e k e r, K. J . 1966. S p a tia l d a ta s y s te m s : O rg a n iz a tio n of s p a tia l d a ta ,
s y s t e m s c o n s id e r a tio n s , s p e c i a l to p ic s . T e c h n ic a l R e p o r ts 4 , 5, 6
o f O ffice o f N a v a l R e s e a rc h T a s k 3 8 9 -1 4 3 , C o n tra c t NONR 1228(37).
D e p a rtm e n t of G e o g ra p h y , N o r th w e s te r n U n iv e rs ity , E v a n sto n , Ill. . 1972. A fr a m e w o r k f o r en c o d in g s p a ti a l d a ta .
A n a ly s is 4 :9 8 -1 0 5 .
G e o g ra p h ic a l
292
D uncan, O. D . , C u z z o rt, R . P . a n d D uncan, B. 1961. S ta t is tic a l g e o g ra p h y :
P r o b le m s in a n a ly z in g a r e a d a ta . T h e F r e e P r e s s , G le n c o e , 111.
E d s o n , D. T . 1973. U n ite d S ta te s G e o lo g ic a l S u rv e y , D e p a r tm e n t o f th e
I n t e r i o r , R e s to n , V a. P e r s o n a l c o m m u n ic a tio n .
E d w ard s, E .
N. Y.
1964.
In fo r m a tio n t r a n s m is s i o n .
C h ap m an & H a ll, New Y o rk ,
E k m a n , G. , L in d m a n , R . a n d W illia m -O ls o n , W. 1963. A p s y c h o p h y s ic a l
s tu d y of c a rt o g r a p h ic s y m b o ls . G e o g ra f is k a A n n a le r 4 5 :2 6 2 -2 7 1 .
E le c tro m a g n e tic C o m p a tib ility A n a ly s is C e n te r. 1969. SAM (S ight A n a ly s is
M odel). E le c tro m a g n e tic C o m p a tib ility A n a ly s is C e n te r , A n n a p o lis, Md.
E m e r s o n , W. 1969. A re v ie w o f g e o g ra p h ic a n d p s y c h o lo g ic r e s e a r c h in to
th e s t r u c t u r e of e n v iro n m e n ta l im a g e s . U n iv e rs ity of M in n e s o ta ,
M in n e a p o lis , M inn. U n p u b lish e d p a p e r.
F a r n s w o r th , G. L . 1970. DIM E a p p lic a tio n s a n d th e c o m p u te r iz e d r e s o u r c e
a llo c a tio n m o d e l. A m e r ic a n S ta t is tic a l A s s o c ia tio n , J o in t S ta tis tic a l
M e e tin g s , D e tro it, M ich.
-
. 1973. C e n s u s U se S tudy, U n ite d S ta te s B u re a u o f th e C e n s u s ,
W a sh in g to n , D. C. P e r s o n a l c o m m u n ic a tio n .
F in k e ls te in , C. B. 1970.
J o u r n a l 2 :1 4 6 -1 5 5 .
D a ta e n t r y te c h n iq u e s .
A u s tr a lia n C o m p u te r
F i s h e r , H. T . 1970. T h e use of c o m p u te r g r a p h ic s in p la n n in g . P a p e r
p r e s e n t e d a t th e N a tio n a l P la n n in g C o n fe re n c e of th e A m e r ic a n S ociety
of P la n n in g O ffic ia ls .
F lo w e rd e w , R . 1973a. A lo g ic o f lo c a tio n a l d e s c r ip tio n s : S o m e il lu s tr a t io n s
f r o m th e c o n te x t of g e o g r a p h ic a l m o b ility . O c c a s io n a l P a p e r s 17.
D e p a rtm e n t of G e o g ra p h y , U n iv e r s ity C o lle g e , L on d o n , E n g lan d .
.- 1973b. T h e u s e of f o r m a l s p a tia l la n g u a g e s in g e o g ra p h y . P a p e r
p r e s e n t e d to th e M eetin g of th e Q u a n tita tiv e M eth o d s Study G ro u p ,
In s titu te of B r i t i s h G e o g ra p h e r s , N e w c a s tle . M im e o g ra p h .
-
. 1974. G eo g ra p h y D e p a rtm e n t, U n iv e r s ity C o lle g e , L o n d o n , E n g lan d .
P e r s o n a l c o m m u n ic a tio n .
F o rre s te r, J.
1961.
I n d u s tr ia l d y n a m ic s .
M. I. T . P r e s s , C a m b r id g e , M a s s.
F o x , I. K . 1973. P la n n in g an d m a n a g e m e n t of e n v iro n m e n t r e s e a r c h
p r o g r a m s . O p tim u m 4 (4 ):3 8 -4 9 . (P u b lic a tio n of th e D e p a r tm e n t of
S upply a n d S e r v ic e s , G o v e rn m e n t of C an a d a, O tta w a , O n t.)
F r e e m a n , H . 1961. On th e en c o d in g o f a r b i t r a r y g e o m e tr ic c o n fig u ra tio n s .
I n s titu te of R a d io E n g in e e r s , T r a n s a c tio n s o n E le c tr o n ic C o m p u te rs
E C - 1 0 : 2 6 0 - 2 6 8 .an d G a rd n e r, L . 1964. A p ic to r ia l jig sa w p u z z le s , th e c o m p u te r s o lu ­
tio n of a p r o b le m in p a t t e r n re c o g n itio n . I n s titu te o f R a d io E n g in e e r s ,
T r a n s a c tio n s on E le c tro n ic C o m p u te rs E C -1 3 :1 1 8 -1 2 7 .
293
G a its , G. M. 1968. M apping by c o m p u te r: LIN M A P.
J o u r n a l 5(2):87.
T h e C a r to g r a p h ic
G a r in , R . A. 1966. A m a tr ix f o r m ula tio n of th e L o w ry m o d e l f o r i n t r a ­
m e tr o p o lita n a c tiv ity lo c a tio n . J o u r n a l of th e A m e r ic a n I n s titu te of
P l a n n e r s 32.
G ould, P . 1965. O n m e n ta l m a p s . M ich ig an I n te r - U n iv e r s i ty C o m m u n ity
o f M a th e m a tic a l G e o g ra p h e rs , D e p a rtm e n t of G eo g rap h y , U n iv e r s ity
o f M ich ig an , A nn A rb o r , M ich.
-a n d W h ite, R .
1 9 7 4 . M en ta l m a p s.
P e n g u in B o o k s, B a ltim o r e , Md.
G rig g , D. B . 1965. T h e lo g ic of r e g io n a l s y s te m s .
o f A m e r ic a n G e o g ra p h e rs 55(3):4 6 5 -4 91.
-
A n n a ls of th e A s s o c ia tio n
. 1967. R e g io n s , m o d e ls an d c l a s s e s . P a g e s 4 6 1 -5 0 9 in C h o rle y ,
R . J . an d H a g g e tt, P . , e d s . , M o d els in g eo g ra p h y . M eth u e n & C o. ,
L o n d o n , E n g lan d .
H ä g e r s t r a n d , T . 1953. In n o v a tio n s för lo p p e t u r k o ro lo g is k sy n p u n k t.
D e p a rtm e n t of G eo g rap h y , U n iv e r s ity of L u n d , L und, Sw eden.
- .
1963. G e o g ra p h ic a l m e a s u r e m e n ts in m ig ra tio n . In S u tte r , J . , e d . ,
H u m an d is p la c e m e n ts . E n t r e ti e n s de M onaco e n s c ie n c e s h u m a in e s ,
M onaco.
-
. 1965. A M onte C a rlo a p p ro a c h to d iffu sio n .
S o cio lo g y 6 ;4 3 -6 7 .
-
. 1967a. T h e c o m p u te r and th e g e o g ra p h e r .
I n s tit u te of B r it is h
G e o g ra p h e r s 4 2 :1 -1 9 .
-
. 1967b. In n o v atio n d iffu sio n a s a s p a ti a l p r o c e s s .
C h ic a g o P r e s s , C h ic ag o , I l l .
-
. 1970. P r e s i d e n t i a l a d d r e s s : W hat ab o u t p eo p le in r e g io n a l s c ie n c e ?
P a p e r s of th e R e g io n a l S c ie n c e A s s o c ia tio n 2 4 :1 -7 .
-
, H a n n e rb e rg , T . a n d O deving, B. , e d s . 1957. M ig ra tio n in Sw eden:
A s y m p o s iu m . L und S tu d ie s in G eo g rap h y , S e rie s B 13. U n iv e r s ity
of L u n d , L und, Sw eden.
E u ro p e a n J o u r n a l o f
T r a n s a c tio n s o f th e
U n iv e r s ity o f
H a g g e tt, P . 1965. L o c a tio n a l a n a ly s is in h u m a n g eo g ra p h y .
( P u b lis h e r s ) , L ondon, E n gland.
-
E d w a rd A rn o ld
. 1969. On g e o g r a p h ic a l r e s e a r c h in a c o m p u te r e n v iro n m e n t.
G e o g ra p h ic a l J o u r n a l 135(4).-
The
an d C h o rle y , R . F . , e d s . 1969. N etw o rk a n a ly s is in g eo g ra p h y .
E d w a rd A rn o ld (P u b lis h e r s ) , L ondon, E n g lan d .
H a ig , R . M. 1926. T o w a rd s a n u n d e rs ta n d in g of th e m e tr o p o lis .
J o u r n a l of E c o n o m ic s 40.
H a ll, P . , e d . 1966. Von T h u n e n 's is o la te d s ta t e .
O x fo rd , E n gland.
Q u a r te r l y
P e rg a m o n P r e s s ,
H a rb a u g h , J . W. an d M e r ria m , D. F . 1967. C o m p u te r a p p lic a tio n s in
s tr a t ig r a p h i c a n a ly s is . J o h n W iley & S ons, New Y o rk , N. Y.
294
H a rd y , E . E . a n d S h elto n , R. L. 1970. I n v e n to ry in g New Y o r k 's la n d u s e and
n a t u r a l r e s o u r c e s . New Y o r k 's F o o d a n d L ife S c ie n c e s 3(4).
-
, S h elto n , R . L. a n d B e lc h e r , D. J . 1971a. New Y o rk S ta te la n d u s e
a n d n a t u r a l r e s o u r c e s in v e n to ry f in a l r e p o r t , v o lu m e I: S u m m a ry
r e p o r t . C e n te r f o r A e r ia l P h o to g ra p h ic S tu d ie s, C o r n e ll U n iv e rs ity ,
I th a c a ,- N. Y.
, S h elto n , R . L ., B e lc h e r , D. J . a n d R o a c h , J . T . 1971b. New Y o rk
S ta te la n d u s e an d n a t u r a l r e s o u r c e s in v e n to ry f in a l r e p o r t , v o lu m e II:
C la s s if ic a tio n an d in v e n to r y m e th o d s . C e n te r f o r A e r ia l P h o to g ra p h ic
S tu d ie s, C o r n e ll U n iv e r s ity , Ith a c a , N. Y.
H a r v a r d U n iv e r s ity . 1968. U s e r s r e f e r e n c e m a n u a l f o r s y n a g r a p h ic c o m ­
p u te r m a p p in g : SYM AP v e r s io n V. L a b o r a to r y f o r C o m p u te r G ra p h ic s
a n d S p a tia l A n a ly s is , H a r v a r d U n iv e r s ity , C a m b rid g e , M a s s .
H a rv e y , D. 1969.
Y o rk , N. Y.
E x p la n a tio n in g e o g ra p h y .
St. M a r ti n 's P r e s s , New
H e a ly , J . 1972. A B L E S : A u to m a te d b ra n c h lo c a tio n a n d e v a lu a tio n s y s te m .
P a p e r s f r o m th e 10th A n n u al C o n fe re n c e of th e U rb a n a n d R e g io n a l
I n f o r m a tio n S y s te m s A s s o c ia tio n , S an F r a n c i s c o , C a lif.
H eb in , O. 1969. C o m p u te r d ra w n is a r i th m i c m a p s .
6 8 (2 ):5 0 -6 3 .
G e o g r a f is k T i d s s c r i f t
H e r b e r t, J . D. a n d S te v e n s, B. 1960. A m o d e l f o r th e d is tr ib u tio n of
r e s i d e n t i a l a c tiv ity in u r b a n a r e a s . J o u r n a l of R e g io n a l S c ie n c e 2:21-36.
H o e lz e l, J .
C a lif.
1973. L o s A n g e le s C ou n ty D e p a rtm e n t of H o s p ita ls , L o s A n g e le s,
P e r s o n a l c o m m u n ic a tio n .
H o lle b , D o r is E . 1969. S o c ia l an d e c o n o m ic in fo r m a tio n f o r u r b a n p lan n in g .
C e n te r f o r U rb a n S tu d ie s, U n iv e r s ity of C h ic a g o , C h ic a g o , I l l .
H o lro y d , M. T . a n d B h a tta c h a y y a , B. K . 1970. A u to m a tic c o n to u rin g of
g e o p h y s ic a l d a ta u s in g b ic u b ic s p lin e in te r p o la tio n . P a p e r 7 0 -5 5 .
G e o lo g ic a l S u rv e y of C a n a d a , O tta w a , O nt.
H oyt, H. 1933. O ne h u n d re d y e a r s of la n d v a lu e s in C h ic a g o .
of C h ic ag o P r e s-s , C h ic a g o , I l l .
U n iv e r s ity
. 1939. T h e s t r u c t u r e a n d g ro w th of r e s id e n tia l n e ig h b o rh o o d s in
A m e r ic a n c i tie s . F e d e r a l H o u sin g A d m in is tr a tio n , W a sh in g to n , D. C.
H uff, D. L . 1964. D efin in g a n d e s tim a tin g a tr a d in g a r e a .
M a rk e tin g 28.
H u rd , R . M. 1903. P r i n c i p l e s of c ity la n d v a lu e s .
New Y o rk , N. Y.
J o u r n a l of
T h e R e c o r d a n d G uide,
Io n , R . J . 1969. T h e g e o g ra p h ic b a s i s of th e DBS g e o -c o d in g s y s t e m f o r
u r b a n a r e a s : A n o v e rv ie w . S ta t is tic s C a n a d a (D om in io n B u r e a u of
S ta t is tic s ) , O tta w a , O nt.
I s a r d , W. 1956. L o c a tio n an d s p a c e -e c o n o m y .
Y o rk , N. Y.
Jo h n W iley & S o n s, New
295
I s a r d , W. 1970. O n n o tio n s of m o d e ls a n d tim e .
S c ie n c e A s s o c ia tio n 25 :7 -3 1 .
P a p e r s o f th e R e g io n a l
-
e t a l. 1960. M ethods of r e g io n a l a n a ly s is : An in tro d u c tio n to r e g io n a l
s c ie n c e . M. I. T . P r e s s , C a m b rid g e , M a s s.
-
an d R e in e r. 1966. R e g io n a l s c ie n c e : R e tr o s p e c t an d p r o s p e c t.
P a p e r s of th e R e g io n a l S cie n c e A s s o c ia tio n 1 6:1-16 .
J a r o , M. A. 1972a. OS AD MATCH: A n a d d r e s s m a tc h in g s y s te m . C e n s u s
U se S tudy C o m p u te r P r o g r a m P a c k a g e II. U. S. D e p a rtm e n t of
C o m m e r c e , B u re a u of th e C e n s u s , W a sh in g to n , D. C.
-
. 1972b. UNIM ATCH: A c o m p u te r s y s t e m f o r g e n e r a liz e d r e c o r d
lin k a g e u n d e r c o n d itio n s of u n c e rta in ty . P r o c e e d in g s of th e A m e r ic a n
F e d e r a t io n of In fo rm a tio n P r o c e s s in g S o c ie ite s 40. A F IP S P r e s s ,
M o n tv ale, N. J .
J a r v i s , C. L . 1971. A m e th o d f o r fittin g p o ly g o n s to f ig u r e b o u n d a ry a r e a .
A u s t r a li a n C o m p u te r J o u r n a l 3 :5 0 -5 4 .
J o h n s o n , T . E . 1963. SK E TC H PA D III: A c o m p u te r p r o g r a m f o r d ra w in g
in t h r e e d im e n s io n s . P r o c e e d in g s of th e A m e ric a n F e d e r a t io n of
I n f o r m a tio n P r o c e s s in g S o c ie tie s 23. A F IP S P r e s s , M o n tv ale, N. J .
J o in t L o c a l A u th o rity . 1972. G e n e ra l in f o rm a tio n s y s t e m f o r p la n n in g .
R e p o rt of th e J o in t L o c a l A u th o rity , S c o ttis h D ev elo p m en t D e p a r tm e n t
a n d D e p a r tm e n t of E n v iro n m e n t S tudy T e a m , London. H e r M a je s ty 's
S ta tio n e r y O ffice, L ondon, E ng.
K a in , J . F . 1962. T h e jo u rn e y to w o r k a s a d e te r m in a n t of r e s id e n tia l
lo c a tio n . R an d P a p e r P -2 4 8 9 , R an d C o r p o r a tio n , S an ta M o n ica, C alif.
K a n to ro w ic h , R . H. , e t a l. 1964. R e g io n a l sh o p p in g c e n tr e s : A p la n n in g
r e p o r t on n o r th w e s t E n g lan d . D e p a rtm e n t of T ow n an d C o u n try
P la n n in g , U n iv e r s ity of M a n c h e s te r , M a n c h e s te r , E n g lan d .
K a o , R . C. 1963. T h e u s e of c o m p u te rs in th e p r o c e s s in g an d a n a ly s is of
g e o g ra p h ic in fo rm a tio n . G e o g ra p h ic a l R eview 5 3 :5 3 0 -5 4 7 .
K in g s to n , P . P . C. H. 1968. A c o m p u te r o r ie n te d g e o g ra p h ic in fo rm a tio n
p r o c e s s in g s y s te m . P a p e r p r e s e n t e d a t th e 10th A n n u al C o n fe re n c e of
th e C a n a d ia n O p e ra tio n a l R e s e a r c h S o c ie ty , T o ro n to Ont.
K le in , F . ( E n g l is h e d .) 1939. E le m e n ta r y m a th e m a tic s f r o m a n a d v a n c e d
sta n d p o in t: G e o m e try . New Y o rk , N. Y.
K o e m a n , C. a n d v a n d e r W e id en , F . L . 1970. T h e a p p lic a tio n o f c o m p u ta tio n
a n d a u to m a tic d ra w in g in s tr u m e n ts to s t r u c t u r a l g e n e ra liz a tio n . T h e
C a r to g r a p h ic J o u r n a l 7 :4 7 -4 9 .
K o la r s , J . F . an d N y stu e n , J . D. 1974. G eo g rap h y : T h e s tu d y of lo c a tio n ,
c u l tu r e a n d e n v iro n m e n t. M c G ra w -H ill, New Y o rk , N. Y.
K o o p m a n s , T . C. 1957. T h r e e e s s a y s on th e s ta t e of e c o n o m ic s c ie n c e .
M c G ra w -H ill, New Y o rk , N. Y.
K ra s n a k e v itc h , J . 1973.
c o m m u n ic a tio n.
K in d le r A s s o c i a te s , H a r v a r d , M a s s.
P e rso n a l
296
K ru m b e in , W. C . 1959. T r e n d s u r f a c e a n a ly s is o f c o n to u r ty p e m a p s w ith
i r r e g u l a r c o n tr o l- p o in t s p a c in g . J o u r n a l of G e o p h y s ic a l R e s e a rc h
6 4 (7 ):8 2 3 -8 3 4 .
-
. 1966. C la s s if ic a tio n of m a p s u r f a c e s b a s e d on th e s tr u c t u r e of
p o ly n o m ia l a n d F o u r n ie r c o e ffic ie n t m a t r i c e s . K a n s a s S ta te G eo lo g ical
S u rv e y C o m p u te r C o n trib u tio n s 7.
L a G a rd e , V. 1973. U. S. A rm y E n g in e e r s , W a te rw a y s E x p e r im e n t S tatio n ,
V ic k s b u rg , M is s . P e r s o n a l c o m m u n ic a tio n .
L a n g , T . 1971. C o m p u te r p r o g r a m s f o r m a p p in g .
L o n d o n , E n g lan d .
A r c h it e c tu r a l P r e s s ,
L e o n tie ff, W. a n d S tro u t, A. 1963. M u ltire g io n a l in p u t-o u tp u t a n a ly s is .
In B a r n a , T . , e d . , S tr u c t u r a l in te rd e p e n d e n c e a n d ec o n o m ic
d e v e lo p m e n t. M a c m illa n , L ondon, E n g lan d .
L o s c h , A. 1954. T h e e c o n o m ic s o f lo c a tio n .
New H a v e n , C onn.
Y a le U n iv e r s ity P r e s s ,
L o w ry , I. S. 1964. A m o d e l of a m e tr o p o lis ,
C o r p o r a tio n , S a n ta M o n ica , C alif.
R M -4 0 3 5 -R C .
-
. 1965. A s h o r t c o u r s e in m o d e l d e s ig n .
I n s tit u te o f P l a n n e r s 31:158-165.
M a c N e ill, J . W. 1971.
O tta w a , O nt.
T h e R an d
J o u r n a l o f th e A m e ric a n
E n v iro n m e n ta l m a n a g e m e n t.
In fo rm a tio n C an a d a,
M a th e ro n , P . 1970. T h e th e o r y of re g io n a liz e d v a r i a b le s . L e s c a h ie r s
du c e n tr e de m o rp h o lo g ie m a th e m a tiq u e de F o n ta in e b le a u 5.
M cD onough, A. 1963. In f o r m a tio n , e c o n o m ic s a n d m a n a g e m e n t s y s te m s .
M cG raw -H ill, New Y o rk , N . Y.
M cK ay, G. A. 1973. C h ie f, C a n a d ia n M e te o ro lo g ic a l S e r v ic e , T o ro n to ,
O nt. P e r s o n a l c o m m u n ic a tio n .
M cK en zie , R . D. 1933.
New Y o rk , N . Y.
T h e m e tro p o lita n c o m m u n ity .
M c G ra w -H ill,
M cL e o d , J . M. 1972. P e r s o n a l c o m m u n ic a tio n s a n d d is p la y o f w o rk at
U N E SC O /IG U S eco n d S y m p o siu m on G e o g ra p h ic a l I n f o r m a tio n S y ste m s ,
O tta w a , O nt.
M e ie r , R . L . 1962. A c o m m u n ic a tio n s t h e o r y of u r b a n g ro w th . J o in t
C e n te r f o r U rb a n S tu d ie s. M. I. T . P r e s s , C a m b r id g e , M a ss.
M e la n d e r, C . , S a lo m o n ss o n , O. a n d S e la n d e r, K . 1971. F R IS A: 2. A s p a tia l
in fo r m a tio n s y s t e m - A p ilo t s tu d y . D a ta r e g i s t r a t i o n - T h e o r e tic a l
a n a ly s is of b a s i c c o n c e p ts . C e n tr a l B o a rd f o r R e a l E s ta te D ata,
S u n d b y b erg , S w eden.
M e r r il l, R . D. 1973. R e p r e s e n ta tio n of c o n to u rs a n d r e g io n s f o r e ffic ie n t
c o m p u te r s e a r c h . C o m m u n ic a tio n s of th e A s s o c ia tio n o f C o m p u tin g
M a c h in e ry 16(2): 69 -8 2 .
297
M e y e r, M. A. 1972. T h e C e n s u s B u r e a u 's a p p ro a c h to g e o g ra p h ic b a s e
(DIM E) f ile m a n a g e m e n t.
P a p e r s f r o m th e 10th A nnual C o n fe re n c e
7 o f th e U rb a n a n d R e g io n a l I n f o r m a tio n
S y s te m s A s s o c ia tio n , San
F r a n c i s c o , C a lif.
M ilg ra m , S. 1972. A p s y c h o lo g ic a l m a p of New Y o rk C ity .
S c ie n tis t 60(2): 194-200.
A m e ric a n
M in is tr y of H o u sin g an d L o c a l G o v e rn m e n t, U. K. 1970. I n fo rm a tio n n e e d s
of th e new p la n n in g s y s te m . R e p o r t of th e J o in t L o c a l A u th o rity ,
S c o ttis h D ev elo p m en t D e p a rtm e n t an d M in is tr y of H o u sin g a n d L o c a l
G o v e rn m e n t S tudy T e a m , L ondon. H e r M a je s ty 's S ta tio n e ry O ffice,
L o n d o n , E n g lan d .
M o n k h o u se , F . J . a n d W ilk in so n , H. R . 1970.
M eth u e n & Co. , L ondon, E n g lan d .
M aps an d d ia g r a m s . (3 rd e d . )
M o r r ill , R . L . 1965. M ig ra tio n an d th e s p r e a d a n d g ro w th of u r b a n s e t t l e ­
m e n t. L u n d S tu d ie s in G eo g ra p h y S e r ie s B 26. G le e ru p , L u n d , Sw eden.
M u rp h y , E . M. 1972. T h e ra n d o m ro u n d in g te c h n iq u e f o r g u a rd in g a g a in s t
il le g a l d is c l o s u r e in p u b lis h e d c e n s u s ta b le s . S ta tis tic s C an a d a,
O tta w a , O nt.
M u rr a y , F . W. 1968. A m e th o d of o b je c tiv e c o n to u r c o n s tr u c tio n . R e p o rt
A D 666830. U n ite d S ta te s D e p a rtm e n t of C o m m e r c e , C le a rin g h o u s e ,
S p rin g fie ld , Va.
M uth, R . T . 1961. T h e s p a ti a l s t r u c t u r e of th e h o u s in g m a r k e t.
th e R e g io n a l S c ie n c e A s s o c ia tio n 7 :2 0 7 -2 2 0 .
New Y o rk S ta te . 1967. M AP01 m a n u a l.
Y o rk S ta te , A lb an y , N. Y.
N o u rs e , H . O.
1968.
P a p e r s of
D e p a rtm e n t of P u b lic W o rk s , New
R e g io n a l e c o n o m ic s .
M c G ra w -H ill, New Y o rk , N. Y.
O b s e r v a to i r e E c o n o m iq u e M e d ite ra n e e n . 1971. G e o c o d ific a tio n . No 2 0 3 /1 .
I n s tit u t N a tio n a l de l a S ta tis tiq u e et d e s E tu d e s E c o n o m iq u e s,
M a r s e il le , F r a n c e .
O ls s o n , A . 1971. F R IS C :3. P r o g r a m s f o r c o o r d in a te p r o c e s s in g . KOSP r e t r i e v a l ; P Y T O M - c a lc u la tio n of a r e a s a n d c i r c u m f e r e n c e s ; RITA 1 p lo ttin g . C e n t r a l B o a r d f o r R e a l E s ta te D a ta , S u n d b y b erg , Sw eden.a n d S e la n d e r, K . 1971. F R IS C :2., D ot m a p s b y c o m p u te r.
B o a r d f o r R e a l E s ta te D a ta , S u n d b y b erg , Sw eden.
C e n tr a l
O w en, E . H . 1972. A n a u to m a te d r e f u s e c o lle c tio n s y s te m . P a p e r s f r o m
th e 10th A n n u al C o n fe re n c e of th e U rb a n a n d R e g io n a l I n fo rm a tio n
S y s te m s A s s o c ia tio n , S an F r a n c i s c o , C a lif.
P e a r s o n , A . K . 1972. LIN M A P an d C O L M A P . P a g e s 9 5 5 -9 5 8 in T o m lin s o n ,
R . F . , ed . , G e o g ra p h ic a l d a ta h a n d lin g . IG U C o m m is s io n o n G e o g r a ­
p h ic a l D a ta S e n sin g an d P r o c e s s in g , O tta w a , O nt.
P e t r i e , G. 1966. N u m e ric a lly c o n tr o lle d m e th o d s of a u to m a tic p lo ttin g an d
d ra u g h tin g . T h e C a rto g ra p h ic J o u r n a l 3 (2 ):6 0 -7 3 .
298
P e u c k e r , T . C . 1972. C o m p u te r c a rto g ra p h y : A w o rk in g b ib lio g ra p h y .
D is c u s s io n P a p e r 12. D e p a rtm e n t of G e o g ra p h y , U n iv e r s ity of
T o ro n to , T o r o n to , Ont.
P f a lt z , J . L . 1967a. M an ip u latio n a n d d is p la y of g e o g ra p h ic a lly d is tr ib u te d
d a ta . S o c ia l S c ie n c e In fo rm a tio n 11 (4): 217-222.
-
. 1967b. MANS: A m a p a n a ly s is s y s te m . T e c h n ic a l r e p o r t
T R -6 7 -4 2 -N S G -3 9 8 . C o m p u te r S c ie n c e C e n te r , U n iv e r s ity o f M a ry la n d ,
C o lle g e P a r k , Md.
-
. 1967c. P a t t e r n r e c o g n itio n VI: MANS - A m a p a n a ly s is s y s te m .
T e c h n ic a l r e p o r t T R - 6 7 - 4 2 - N SG -398. C o m p u te r S cie n c e C e n te r ,
U n iv e r s ity of M a ry la n d , C o lle g e P a r k , Md.
-
a n d R o s e n fe ld , A. 1967. C o m p u te r r e p r e s e n t a ti o n o f p la n a r r e g io n s
b y t h e i r s k e le to n s . C o m m u n ic a tio n s of th e A s s o c ia tio n o f C o m p u tin g
M a c h in e ry 10(2): 119-123.
P h ilb r i c k , A . K . 1967. T h e E r i e p r o je c t: S p a tia l t e r m s o f r e f e r e n c e . P a p e r
p r e s e n t e d a t th e U n iv e r s ity o f W e s te rn O n ta rio , D e p a r tm e n t of
G e o g ra p h y C o n fe re n c e on th e E r i e P r o je c t. U n iv e r s ity o f W e s te r n
O n ta r io , L o n d o n , O nt.
P h ill ip s , J . 1972a. T A R E L A II: A ta b u la tio n re q u e s t la n g u a g e : U s e r 's
m a n u a l. G e n e r a l S u rv e y S y s te m s-, S ta t is tic s C a n a d a , O tta w a , Ont.
. 1972b. S a fe g u a rd in g a g a in s t d is c l o s u r e in STA T P A K v e r s io n 3.
G e n e r a l S u rv e y S y s te m s , S ta t is tic s C a n a d a , O tta w a , O nt.
P h ill ip s , R . L . 1972. I n te r a c tiv e m a p p in g f o r e n v ir o n m e n ta l s y s te m s .
A e r o s p a c e E n g in e e r in g D e p a rtm e n t, U n iv e rs ity of M ich ig an , Ann
A r b o r , M ich. M im e o g rap h .
P i e r c e , J . R . 1961. S y m b o ls, s ig n a ls a n d n o is e : T h e n a tu r e a n d p r o c e s s
o f c o m m u n ic a tio n . H a r p e r & R ow , New Y o rk , N . Y.
P i t t s , F . 1963. P r o b le m s in c o m p u te r s im u la tio n of d iffu sio n .
th e R e g io n a l S c ie n c e A s s o c ia tio n 11:111-119.
P a p e r s of
P o d e h l, W. M. 1972a. S T A T P A K a n d i t s d a ta b a s e : A g u id e f o r c re a tin g
a S T A T P A K d a ta b a s e . G e n e ra l S u rv e y S y s te m s , S ta t is tic s C an ad a,
O tta w a-, O nt.
. 1972b. S T A T P A K ( v e rs io n 3) g e n e ra l in fo rm a tio n m a n u a l.
S u rv e y S y s te m s , S ta tis tic
- s C a n a d a , O tta w a , O nt.
G e n e ra l
. 1973. G e n e r a l S u rv e y S y s te m s , S ta t is tic s C a n a d a , O tta w a , O nt.
P e r s o n a l c o m m u n ic a tio n .
P o r t e r , J . 1965. T h e v e r t ic a l m o s a ic : A n a n a ly s is of s o c ia l c l a s s and
p o w e r in C a n a d a . U n iv e rs ity of T o ro n to P r e s s , T o r o n to , O nt.
P . R . C. In fo r m a tio n S c ie n c e s C om pany. 1973. L in e a l in p u t s y s t e m u s e r s
m ra,n uHa.l. 1956.
P u b lis Sh tu
e dd ie
f osr of
A irh uFmoarnc ec hSaynsntee m
m.an In
d, G
Q u a s tle
l csa pCaocmity
C rhife fris
r ys, AEir. C . ,
F
s e ,a tio
R onmth
e ,e oN.
e do r. ,c eInBfoarm
r yY.
. P r o c e e d in g s of th e T h ir d L o n d o n S y m p o siu m ,
1955. B u tte r w o r th , L o n d o n , E n g lan d .
299
R a y n e r , J . N. 1971.
E n g lan d .
-
A n in tr o d u c tio n to s p e c t r a l a n a ly s is .
P io n , L o ndon,
. 1974. T h e tim e e le m e n t in s p a ti a l p r o c e s s . P a p e r p r e s e n te d a t th e
S y m p o siu m on G e o g ra p h ic A n a ly s is a n d U n d e rs ta n d in g S p a tia l P r o c e s s .
D e p a rtm e n t of G e o g ra p h y , U n iv e rs ity of M ichigan, A nn A r b o r , M ich.
R e illy , W. J . 1929. M eth o d s f o r th e s tu d y of r e t a i l r e la tio n s h ip s . B u lle tin
2994, R e s e a r c h M onograph 4. U n iv e r s ity of T e x a s , A u stin , T e x a s .
R h in d , D. W. 1971. T o w a rd s in s ta n t an d e ffic ie n t m a p s: T h e w o rk of th e
E x p e r im e n ta l C a r to g r a p h y U nit. R eview of G e o g ra p h ic a l M o n ito rin g
25(4): 3 9 1 -398.
R ic h a r d s o n , H. W. 1969. E le m e n ts of re g io n a l e c o n o m ic s . . P e n g u in B o o k s,
H a rm o n d s w o rth , M id d le se x .
R o b in s o n , A. H. 1956. T h e n e c e s s i ty of w e ig h tin g v a lu e s in c o r r e l a ti o n
a n a ly s is of a r e a d a ta . A n n a ls of th e A s s o c ia tio n of A m e ric a n
G e o g r a p h e rs- 4 6 :2 3 3 -2 3 6 .
. 1969. E le m e n ts of c a rto g r a p h y (3 rd e d . ).
New Y o rk , N. Y.
R o g e r s , A. 1968.
d is tr ib u tio n .
Jo h n W iley & S ons,
M a tr ix a n a ly s is of in t e r r e g io n a l p o p u la tio n g ro w th an d
U n iv e rs ity of C a lif o r n ia P r e s s , B e rk e le y , C alif.
R u s h to n , G . , H o rto n , F . E . , L in d b e rg , J . B. , M cN ulty, M. L . , R e y n o ld s, D. R . ,
S a lis b u r y , N. E . , a n d T a y lo r , P . 1971. Q u a n tita tiv e g eo g rap h y :
A c h ie v e m e n ts an d p r o s p e c t s . F in a l R e p o r t, E T L -C R - 7 1 - 1 2 . U .S .
A rm y E n g in e e r T o p o g ra p h ic L a b o r a to r ie s , R e s e a r c h I n s titu te ,
D e p a rtm e n t of th e A rm y , F o r t B e lv o ir, Va.
S a lm o n a , J . 1974. O pé r a t io n P ilo t e I n te r m in i s té r i e l l e s u r le s Donné e s
A d m in is tr a tiv e s , M a r s e il le , F r a n c e . P e r s o n a l c o m m u n ic a tio n .
S a lo m o n ss o n , O. 1969. D ata b a n k in g s y s t e m s f o r u rb a n p la n n in g .
P r o c e e d in g s of th e C o n fe re n c e on
In fo r m a tio n a n d P la n n in g 2. C E S - I P - 8 .
C e n tre f o r E n v ir o n m e n ta l -S tu d ie s, L o n d o n , E n g lan d .
. 1973. N O R D PLA N , S k e p p sh o lm e n , S 111 49 S to ck h o lm , Sw eden.
P e r s o n a l c o m m u n ic a tio n .
S c h m id t, A. 1966. SY M A P, a u s e r s m a n u a l.
P la n n in g- C o m m is s io n , L a n s in g , M ich.
T r i- C o u n ty R e g io n a l
. 1970. S e le c te d p r o je c ts 1966-1970. L a b o r a to r y f o r C o m p u te r
G r a p h ic s an d S p a tia l A n a ly s is , H a r v- a r d U n iv e rs ity , C a m b rid g e ,
. 1972a. SYM A P. P a g e s 934 -9 3 8 in T o m lin s o n , R . F . , e d . ,
G e o g ra p h ic a l d a ta h a n d lin g . IGU C o m m is s io n on G e o g ra p h ic a l
S e n s in g a n d P r o c e s-s in g , O tta w a , O nt.
.
1972b.
S e n s in g
M a s s.
D ata
SYMVU. P a g e s 1041-1044 in T o m lin s o n , R . F . , ed . ,
G e o g ra p h ic a l d a ta h a n d lin g . IGU C o m m is s io n o n G e o g ra p h ic a l D ata
an d P r o c e s s in g , O tta w a , O nt.
300
S c h m id t, W. E . 1969.
29 (1 ):1 0 1 -1 0 6 .
-
T h e A U TO M A P s y s te m .
S u rv ey in g an d M apping
. 1970. C a r to g r a p h ic a u to m a tic m a p p in g p r o g r a m (CAM).
D o c u m e n ta tio n a c c e s s i o n N o. P B 191779. U. S. D e p a rtm e n t of
C o m m e rc e , C le a rin g h-o u s e , S p rin g fie ld , Va.
. 1973. C e n t r a l In te llig e n c e A gency, W a sh in g to n , D. C.
C o m m u n ica tio n .
P e rso n a l
S c ie n c e C o u n c il o f C a n a d a . 1969. S cie n c e an d te c h n ic a l in fo r m a tio n in
C an a d a: P a r t II - G o v e rn m e n t d e p a rtm e n ts an d a g e n c ie s . S p e c ia l
S tudy 8. I n f o r m a tio n C a n a d a , O tta w a , O nt.
S e e m a n , I.
1973.
P e r s o n a l c o m m u n ic a tio n .
S e la n d e r , K . 1970. F R IS C : l . R e g is tr a tio n a n d s to r in g of c o o r d in a te s .
C e n t r a l B o a rd f o r R e a l E s ta te D ata , S u n d b y b erg , Sw eden.
S h elto n , R . L . an d D im o c k , R . A. 1971a. New Y o rk S ta te la n d u s e and
n a t u r a l r e s o u r c e s in v e n to r y fin a l r e p o r t , v o lu m e IV: P L A N M A P II
a n d D A T A L IST I u s e r m a n u a ls . C e n te r f o r A e r ia l P h o to g ra p h ic
S tu d ie s, C o r n e ll U n iv
- e r s ity , I th a c a , N. Y.
. 1971b. New Y o rk S ta te la n d u s e an d n a t u r a l r e s o u r c e s in v e n to r y
f in a l r e p o r t , v o lu m e V: C o m p u te r p r o g r a m s . C e n te r f o r A e r ia l P h o to ­
g r a p h ic s tu d ie s , C o r n e ll U n iv e rs ity , Ith a c a , N. Y .
S h elto n , R . L . , D im o c k , R . A. a n d H ope, J . M. 1971. New Y o rk S ta te la n d u s e
a n d n a t u r a l r e s o u r c e s in v e n to ry f in a l r e p o r t , v o lu m e III: D ata s y s t e m
an d d a ta p r o c e s s in g . C e n te r f o r A e r ia l P h o to g ra p h ic S tu d ie s, C o r n e ll
U n iv e r s ity , I th a c a , N. Y.
S in g e r, H . W. 1936. T h e 'C o u rb e d e s p o p u la tio n s ': A p a r a l l e l to P a r e t o 's
la w . E c o n o m ic J o u r n a l 46.
S in to n , D. a n d S te in itz , C. 1969. GRID: A u s e r s r e f e r e n c e m a n u a l.
L a b o r a to r y f o r C o m p u te r G r a p h ic s an d S p a tia l A n a ly s is , H a r v a r d
U n iv e r s ity , C a m b rid g e , M a s s,
S o lo sk o , R . B . 1973. A s e m i- a u to m a tic s y s t e m f o r d ig itiz in g b a th y m e tr ic
c h a r t s . C a ls p a n r e p o r t V F -5 2 0 6 -X I . F in a l r e p o r t . C o n tr a c t
N 0 0 0 1 4 -7 2 -C 0 4 6 6 . P r e p a r e d f o r th e L o n g R a n g e A c o u s tic P r o p a g a tio n
P r o j e c t , O ffice of N a v a l R e s e a rc h . D e p a rtm e n t of th e N avy,
W a sh in g to n , D. C.
S ta t is tic s C a n a d a . 1972a. GRDSR: F a c t s b y s m a l l a r e a s - A n in tro d u c tio n .
M e th o d o lo g y a n d S y s te m s B ra n c h -, S ta tis tic s C a n a d a , O tta w a , O nt.
. 1972b. G RDSR: G e o g ra p h ic a lly r e f e r e n c e d d a ta s to r a g e an d r e t r i e v a l
s y s t e m - A te c h n ic a l d e s c r ip tio n . M ethodology an d S y s te m s B ra n c h ,
S ta t is tic s C a n a d a , O tta w a , Ont.
-
. 1972c. G RDSR: G u id e lin e s f o r re q u e s tin g g e o g ra p h ic a l a r e a s .
C e n s u s U s e r I n q u ir y S e rv ic e , C e n s u s D iv is io n , S ta tis tic s C a n a d a ,
O tta w a , O nt.
301
S te a , D. 1969. T h e m e a s u re m e n t o f m e n ta l m a p s : A n e x p e rim e n ta l m o d e l
f o r s tu d y in g c o n c e p tu a l s p a c e s . S tu d ie s in G eo g ra p h y 17: B e h a v io r a l
p r o b le m s in g e o g ra p h y : A s y m p o s iu m . N o rth w e s te r n U n iv e r s ity ,
E v a n s to n , I l l .
S te in e r , D. 1970. G EO M A P. P e r s o n n e l c o m m u n ic a tio n , U n iv e r s ity of
W a te rlo o , W a te rlo o , O nt.
S u th e rla n d , I. E . 1963. SKETCH PA D : A m a n - m a c h in e g r a p h ic a l c o m m u n i- .
c a tio n s y s te m . P r o c e e d in g s of th e A m e ric a n F e d e r a t io n of I n fo rm a tio n
P r o c e s s i n g S o c ie tie s 2 3:324-346. A F IP S P r e s s , M o n tv ale, N .J .
S w itz e r, P . 1973. E s tim a tio n of th e a c c u r a c y o f q u a lita tiv e m a p s . P a p e r
p r e s e n t e d a t th e N A TO A d v an ced Study In s titu te C o n fe re n c e on
D is p la y a n d A n a ly s is o f S p a tia l D ata , N o ttin g h a m , E n g lan d .
S w itz e r, W. 1973. L a n d M an ag em en t In fo rm a tio n S y s te m s , L a n d s
D ir e c t o r a te , E n v iro n m e n t C an a d a, O tta w a , O nt.
S y m o n s, D. C. 1972a. A u to m a tic m a p p in g an d i t s r e l a ti o n to u r b a n
in f o rm a tio n s y s t e m s . T h e C a n- a d ia n S u rv e y o r 26(5) :5 4 5 -55 7 .
. 1972b. P a r c e l g eo c o d in g f o r u rb a n a n d r u r a l in fo rm a tio n . In
G eo co d in g '72. P a p e r s of th e G e o g ra p h ic B a s e F ile S p e c ia l I n te r e s t
G ro u p , 10th A n n u al C o n fe re n c e , U rb a n a n d R e g io n a l I n f o r m a tio n
S y s te m s A s s o c ia tio n , S an F r a n c i s c o , C a lif.
T a r r a n t , J . R . 1968. C o m p u te rs in g eo g ra p h y . G eo A b s t r a c t s , S ch o o l of
E n v iro n m e n ta l S tu d ie s, U n iv e r s ity of E a s t A n g lia , N o rw ic h , E n g lan d .
T a y lo r , L . R . 1973. C o m p re h e n s iv e P la n n in g O rg a n iz a tio n , S an D iego
C o u n ty , San D iego, C a lif. P e r s o n a l c o m m u n ic a tio n .
T h o m a s , A . 1972. O BLIX . D e p a rtm e n t of G eo g ra p h y , U n iv e r s ity of
E d in b u rg h , E d in b u rg h , S co tlan d . P e r s o n a l c o m m u n ic a tio n .
T h o m a s , E . N. a n d A n d e rs o n , D. L. 1965. A d d itio n a l c o m m e n ts on
w e ig h tin g v a lu e s in c o r r e l a ti o n a n a ly s is o f a r e a l d a ta . A n n a ls o f th e
A s s o c ia tio n of A m e ric a n G e o g ra p h e rs 5 5 :4 9 2 -5 0 5 .
T h o m p so n , D. R . 1967. A c a rto g r a p h ic s c a n n e r . P r o c e e d in g s o f th e 27th
A n n u a l M eetin g of th e A m e ric a n S o cie ty o f P h o to g r a m m e tr y - A m e r ic a n
C o n g r e s s on S u rv e y in g an d M apping, W a sh in g to n , D. C.
T o b in , J . 1953. R e s e a rc h on f u ll e m p lo y m e n t an d in fla tio n . U n p u b lish ed
m e m o r a n d u m p r e p a r e d f o r th e S o cia l S c ie n c e R e s e a r c h C o u n c il, U. S. A.
T o b l e r , W .R . 1962. A c la s s if ic a tio n of m a p p r o je c ti o n s .
A s s o c ia tio n of A m e ric a n -G e o g ra p h e rs 5 2 :1 9 6 -2 7 5 .
, 1963. G e o g ra p h ic a r e a an d m ap p r o je c tio n s .
5 3 :5 9- -7 8 .
A n n a ls o f th e
G e o g ra p h ic a l R eview
. 1964a. A u to m a tio n in th e p r e p a r a tio n of th e m a tic m a p s .
o f th e B r i t i s h C a rto g ra p h ic
- S o cie ty , J u n e 1 9 6 4 :1 -7 .
Jo u rn al
. 1964b. C o m p u ta tio n of th e c o rre s p o n d e n c e of g e o g r a p h ic a l p a tte r n s .
P a p e r s of th e R e g io n a l S cie n c e A s s o c ia tio n 1 5:131-1 3 9 .
302
T o b le r , W. R . 1965. A u to m a tio n in th e p r e p a r a tio n of th e m a tic m a p s.
C a r to g r a p h ic J o u r n a l 2(1): 32 -38.
-.
1966. N u m e ric a l m a p g e n e ra liz a tio n a n d n o te s o n th e a n a ly s is of
g e o g ra p h ic a l d is tr ib u tio n s . D is c u s s io n P a p e r 8. M ich ig an I n te r U n iv e r s ity C o m m u n ity of M a th e m a tic a l G e o g ra p h e r s . D e p a rtm e n t of
G e o g ra p h y , U n iv e r s ity of M- ich ig an , A nn A r b o r , M ich.
, ed . 1970. S e le c te d c o m p u te r p r o g r a m s .
U n iv e r s ity of M ich g ian , A nn A r b o r , M ich.
-
D e p a rtm e n t o f G eo g rap h y ,
e t a l. 1968. T h e p h ilo so p h y of m a p s . D is c u s s io n P a p e r 12.
M ich ig an I n te r - U n iv e r s i ty C o m m u n ity o f M a th e m a tic a l G e o g r a p h e r s ,
D e p a rtm e n t of G e o g ra p h y , U n iv e rs ity of M ich ig an , A nn A r b o r , M ich.
T o m lin s o n , K. R . a n d H uff, A. 1972. T h e c r e a tio n of g e o -c o d e d f il e s ,
a e r i a l r e t r i e v a l a n d m a p p in g . P r o c e e d in g s of th e P la n n in g an d
T r a n s p o r t R e s e a r c h a n d C o m p u ta tio n Co. L td . S y m p o s iu m o n
D a ta M a n a g e m e n t, L o n d o n , E n g lan d .
T o m lin s o n , R . F . 1962. C o m p u te r m a p p in g : A n in tro d u c tio n to th e u s e of
e l e c tr o n i c c o m p u te r s in th e s to r a g e , c o m p ila tio n an d a s s e s s m e n t of
n a t u r a l a n d e c o n o m ic d a ta f o r th e e v a lu a tio n of m a r g in a l la n d s .
R e p o rt p r e s e n t e d to th e N a tio n a l L a n d C a p a b ility I n v e n to ry S e m in a r
h e ld u n d e r th e d ir e c tio n of th e A g r ic u ltu r a l R e h a b ilita tio n a n d
D e v e lo p m e n t A d m in is tr a tio n , C a n a d a D e p a rtm e n t of A g r ic u ltu r e ,
O tta w a-, O nt.
. 1963. F e a s ib i lit y r e p o r t of c o m p u te r m a p p in g s y s te m .
A ir S e rv ic e s L td . , O tta w a , Ont.
-
S p a rta n
. 1967. A n in tr o d u c tio n to th e g e o g ra p h ic in fo r m a tio n s y s t e m o f th e
C an a d a L a n d In v e n to ry . D e p a rtm e n t of F o r e s t r y an d R u r a l D e v e lo p
m e n t, O tta
- w a , O nt.
. 1968. A g e o g ra p h ic in f o rm a tio n s y s t e m f o r r e g io n a l-p la n n in g .
P a g e s 200 -2 1 0 in S te w a rt, G. A . , e d . , L a n d e v a lu a tio n . P a p e r s of
a CSIRO S y m p o s iu m o rg a n iz e d in c o o p e ra tio n w ith UNESCO.
M a c m illa n of A u s t r a li a , South
M elb o u rn e , V ic to ria .
. 1971. T h e e c o n o m ic , s o c io lo g ic a l a n d p o li tic a l n a tu r e o f d a t a b a n k s
f o r d e v e lo p m e n t. P a g e s 2 0 -3 1 in D a ta b a n k s f o r d e v e lo p m e n t.
P r o c e e d in g s of th e I n te r n a tio n a l E x p e r t M eetin g on D ata B a n k s f o r
D e v e lo p m e n t, - S a in t-M a x im in , F r a n c e . I. N. S. E . E . , O b s e r v a to ir e
É co n o m iq u e Mé d i t e r r a n é e n , M a r s e ille , F r a n c e .
-
, ed . 1972. G e o g ra p h ic a l d a ta h a n d lin g (S y m p o siu m e d . ). U N ESC O /
IGU S econd S y m p o s iu m on G e o g ra p h ic a l In fo rm a tio n S y s te m s , O ttaw a,
O nt. IGU C o m m is s io n on G e o g ra p h ic a l D a ta S e n s in g a n d P r o c e s s in g ,
O tta w a , O nt.
T r e ic h e l , R . 1973. N a tio n a l C iv il D e fe n s e C o m p u te r F a c i lit y , O ln ey , Md.
P e r s o n a l c o m m u n ic a tio n .
T ro w b r id g e , C . C. 1913. On fu n d a m e n ta l m e th o d s of o r ie n ta tio n an d
im a g in e r y m a p s . S c ie n c e 38.
303
U n id a ta , In c .
1973.
IN SIGHT u s e r s g u id e .
U n id a ta , I n c . , A nn A r b o r , M ich.
U n iv e r s ity of I llin o is . 1970. NARIS: T h e n a t u r a l r e s o u r c e s in fo rm a tio n
s y s te m . Illi a c IV p r o je c t, in c o o p e ra tio n w ith th e N o r th e a s t I llin o is
N a tu r a l R e s o u rc e S e rv ic e C e n te r , U rb a n a , I l l .
U . S. B u r e a u of C e n s u s . 1970a. C e n s u s u s e stu d y : D a ta u s e s in h e a lth
p la n n in g . R e p o rt 8. U. S. D e p a rtm e n t of C o m m e r c e , B u re a u o f th e
C e n s u s , W ash- in g to n , D. C.
.
1970b. C e n s u s u s e . s tu d y r e p o r t s e r i e s , v o lu m e s 1 to 13. U .S .
D e p a r tm e n t of C o m m e rc e ,
B
- u re a u of th e C e n s u s , W ash in g to n , D. C.
. 1971a. U se of a d d r e s s co d in g g u id e s in g e o g ra p h ic c o d in g : C a s e
s tu d ie s . R e p o r t GE60 N o
1 . U. S. G o v e rn m e n t P r in ti n g O ffice,
W a sh in g to n , D. C.
-
. 1971b. C e n s u s u s e stu d y : g eo c o d in g w ith A DM ATCH - A L o s A n g e le s
e x p e rie n c e . R e p o rt 14. U. S. D e p a rtm e n t of C o m m e r c e , B u re a u of
th e C e n s u s , W ash
- in g to n , D. C.
. 1971c . C e n s u s u s e stu d y : H e a lth in fo r m a tio n s y s t e m II. R e p o r t 12,
U. S. D e p a rtm e n t of
C o m m e rc e , B -u r e a u of th e C e n s u s , W a sh in g to n , D .C .
. 1971d. C e n s u s u s e stu d y : C o m p u te r r e s o u r c e a llo c a tio n m o d e l
(CRA M ). R e p o r t 13. U. S.
D e p a rtm e n t of C o m m e r c e , B u r e a u o f th e
C e n s u s , W ash- in g to n , D. C.
. 1972. D IM E: A g e o g ra p h ic b a s e f il e p a c k a g e . U. S. D e p a r tm e n t of
C o m m e r c e , B u re a u of
th e C e n s u s , W a sh in g to n , D. C.
. 1973. C e n s u s u s e stu d y : DIM E w o rk s h o p s - A n in t e r im r e p o r t .
U. S. D e p a r tm e n t of
C o m m e r c e , B u r e a u of th e C e n s u s , W ash in g to n ,D .C .
U. S. D ep t, of C o m m e rc e . 1967. A p r o g r a m of c o m p o s ite e c o n o m ic an d
g e o g ra p h ic a n a ly s is u s in g a c o m p u te r m a p p in g s y s te m . U. S. D e p a r t­
m e n t of C o m m e rc e , O ffice of R e g io n a l D ev elo p m en t P la n n in g ,
W a sh in g to n , D. C.
U. S. G e o lo g ic a l S u rv e y (U. S. G. S .) 1969. P r o c e e d in g s of th e s y m p o s iu m on
m a p a n d c h a r t d ig itiz in g , O c to b e r 1969. G e o lo g ic a l S u rv e y C o m p u te r
C o n trib u tio n 5. T o p o g ra p h ic D iv is io n , G e o lo g ic a l S u rv e y , U. S.
D e p a rtm e n t of th e I n te r io r , W a sh in g to n , D. C.
V ogt, I v e r s a n d A s s o c ia te s . 1966. C o m p re h e n s iv e la n d u s e in v e n to r y
p r o c e d u r e s m a n u a l f o r d a ta c o lle c tio n a n d a n a ly s is . C o m m o n w e alth
of M a s s a c h u s e tts , B o s to n R e g io n a l P la n n in g P r o j e c t , B o s to n , M a s s.
V on T h u n e n , J . H. 1826. D e r is o l i e r t e S ta a t in B e z ie h u n g a u f L a n d w ir ts c h a f t
u n d N a tio n a lök o n o m ie . H am b u rg . ( T r a n s la tio n in H a ll, P . , e d . ,
1966. V on T h u n e n 's is o la te d s ta te . - P e r g a m o n P r e s s , O x fo rd , E n g lan d .
W a rd , N. 1962. T h e p u b lic p u r s e : A s tu d y in C a n a d ia n d e m o c ra c y .
U n iv e r s ity of T o ro n to P r e s s , T o ro n to , O nt.
W a rn e ry d . O. 1968. I n te rd e p e n d e n c e in u r b a n s y s te m s .
A k tie b o la g , G o teb o rg , Sw eden.
R eg io n k o n su lt
304
W a rn tz , W. 1971. C o m p u te r g r a p h ic s a n d th e o r e ti c a l g e o g ra p h y . In
R e s e a r c h I n s titu te l e c t u r e s on g e o g ra p h y , s p e c ia l r e p o r t E T L SR 71 1.
U. S. A rm y E n g in e e r T o p o g ra p h ic L a b o r a to r ie s , F o r t B e lv o ir , Va.
W augh, T . C. 1972. T h e c h o r o p le th m a p p in g s y s te m . I n te r - U n iv e r s ity
R e s e a r c h C o u n c ils S e r ie s R e p o r t 7. E d in b u rg h C atalo g u e No. 18.900.103.
S c ie n tific a n d S o c ia l S c ie n c e s P r o g r a m L ib r a r y , U n iv e r s ity of
E d in b u rg h , E d in b u rg h , S co tlan d .
W e b b e r, M. M. 1963. O r d e r in d iv e r s ity : C o m m u n ity w ith o u t p ro p in q u ity .
In W ingo, L . , e d . , C it ie s a n d s p a c e : T h e f u tu re u s e o f u rb a n la n d .
J o h n s H o p k in s P r e s- s , B a l tim o r e , Md.
. 1964. T h e u r b a n p la c e a n d n o n p la c e u rb a n r e a lm . I n W e b b er, M. M.
e t a l. E x p lo r a tio n s in to u r b a n s t r u c t u r e . U n iv e rs ity o f P e n n s y lv a n ia
P r e s s , P h ila d e lp h ia , P a .
W e in e r , N. 1930. G e n e r a lis e d h a r m o n ic a n a ly s is . A c ta M a th e m a tic a
5 5 :1 1 7 -2 5 8 . ( R e p rin te d M.
- I. T . P r e s s 51, 1964.)
. 1958. N o n - lin e a r p r o b le m s in ra n d o m th e o r y .
C a m b rid g e , M a s s .
M. I. T . P r e s s ,
W e s te r f ie ld , F . 1973. R e g io n a l P la n n in g C o u n c il, B a ltim o r e , Md.
P e r s o n a l c o m m u n ic a tio n .
W hite., M .S . 1973. • C e n s u s U se Study, U .S . D e p a rtm e n t o f C o m m e rc e ,
B u re a u o f th e C e n s u s , W a sh in g to n , D. C. P e r s o n a l co m m u n ic a tio n .
W h ite, R . R . 1970. G e o g ra p h ic in f o rm a tio n an d th e in t e r p r e ta tio n of
c h o ro p le th m a p s . P h . D. D is s e r ta t io n , D e p a rtm e n t o f G eo g rap h y ,
U n iv e r s ity of B r is to l , B r i s t o l , E n g lan d .
W illia m s , C. M. 1973. C o m p u te r S c ie n c e D e p a rtm e n t, P e n n s y lv a n ia
S ta te U n iv e r s ity , P h ila d e lp h ia , P a .
W illia m s , R . 1968. D a ta s t r u c t u r e s : A n a n n o ta te d b ib lio g ra p h y .
D e p a r tm e n t of E l e c t r i c a l E n g in e e rin g , New Y o rk U n iv e r s ity , New Y o rk ,
N . -Y.
. 1971. A s u r v e y of d a ta s t r u c t u r e s f o r c o m p u te r g r a p h ic s s y s te m s .
C o m p u tin g S u rv e y s 3(1): 1 -22.
W illis , J . 1 9 7 L D e sig n i s s u e s f o r u r b a n a n d r e g io n a l in fo rm a tio n s y s te m s .
W o rk in g p a p e r C E S -W P -7 1 . C e n tre f o r E n v iro n m e n ta l S tu d ie s,
L ondon, E n g lan d .
W ils o n , A. G. 1967. A s t a t i s t i c a l th e o r y of s p a tia l d is tr ib u tio n m o d e ls .
T r a n s p o r t a tio n R e-s e a r c h 1:2 5 3 -2 6 9 .
. 1968. I n te r r e g io n a l c o m m o d ity flo w s : E n tro p y m a x im isin g
a p p ro a c h e s . W o rk in g p a p e r C E S - W P - 19. C e n tre f o r E n v iro n m e n ta l
S tu d ie s, L o n d- o n , E n g lan d .
. 1969a. D e v e lo p m e n t of s o m e e le m e n ta r y r e s id e n tia l lo c a tio n m o d e ls .
J o u r n a l of R e g io n a l S- c ie n c e 9 (3):3 7 7 -3 8 5 .
. 1969b. E n tr o p y in u r b a n a n d r e g io n a l m o d e llin g . W o rk in g p a p e r
C E S -W P -2 6 . C e n tr e f o r E n v ir o n m
- e n ta l S tu d ie s, London, E n g lan d .
. 1969c. D is a g g re g a tin g e l e m e n t a r y r e s id e n tia l lo c a tio n m o d e ls .
W o rk in g p a p e r C E S -W P -3 7 , C e n tre f o r E n v iro n m e n ta l S tu d ie s, London,
E n g lan d .
305
W ilso n , N. L . 1955. S p a c e , tim e and in d iv id u a ls .
52(22):589 -598.
J o u r n a l o f P h ilo s o p h y
W ingo, L. J r . 1 9 6 la . An e c o n o m ic m o d e l of th e u tiliz a tio n o f u r b a n la n d
f o r r e s i d e n t i a l p u r p o s e s . P a p e r s of th e R e g io n a l S cie n ce A s s o c ia tio n
7 :1 9 1--2 0 5 .
.
1961b. T r a n s p o r t a tio n an d u r b a n la n d . J o h n s H o p k in s P r e s s ,
B a ltim o r e , Md.
Z ip f, G. K . 1 9 4 9 . H u m a n b e h a v io r an d th e p r in c ip le o f le a s t e f f o r t.
A d d is o n -W e s le y P u b lis h in g C o ., R e a d in g , M a s s .
306
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T E C H N IC A L D E S C R IPT IO N O F T H E CANADA
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I n i t i a l i z a t i o n a n d c o n t r o l ..................................................................................
C o m p u t e : S e c t i o n s i z e a n d g e t f i r s t s e c t i o n ......................................
C o m p u t e V - v a l u e s .............................................................................................
V e r t e x t a b l e i n i t i a l i z a t i o n ................................................................. ..............
C l o u d e l i m i n a t i o n .................... ...............................................................................
B o u n d a r y t r a c i n g a n d c o l o u r i n g .................................................................
W r i t e s e g m e n t r e c o r d a n d g e t n e x t s e g m e n t ..................................
W r i t e e q u i v a l e n t c o l o u r s ..................................................................................
C o r n e r p o i n t l o c a t i o n ................................................ .................... ..
E r r o r r o u t i n e ..............................................................................................................
U p d a t e o f m a p c o n t r o l b l o c k ..........................................................................
P h a s e 2 ...........................................................................................................................................
I n i t i a l i z a t i o n a n d c o n t r o l ..................................................................................
L o c a t i o n o f m a p c o r n e r s ................................................... ..
C o m p u t e t r a n s f o r m a t i o n o f c o e f f i c i e n t s .....................................
T r a n s f o r m d e s c r i p t o r - r e l a t e d r e f e r e n c e c o o r d in a te s
to G C S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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R e s o l u t i o n r e d u c t i o n - s c a l e c h a n g e .................... .................................. 3 4 6
G a p c l o s i n g . . . ............................................................................................................ 3 4 7
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re c o rd s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E r r o r a n a l y s i s ......................... ................
W r i t e m a p c o n t r o l b l o c k a n d e n d o f p h a s e ................................
P h a s e 3 . . . . ........................................... ................................. ................................. .................
I n i t i a l i z a t i o n a n d c o n t r o l ..................................................................................
F r a m i n g . . . . ..............................................................................................................
C o l o u r e q u i v a l e n c e r e s o l u t i o n ...................................................................
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C o v e ra g e in itia liz a tio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I n it ia l iz e a n d p r o c e s s f r a m e r e c o r d s ........................................... 355
R e a d c o lo u r r e c o r d s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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T r a c e b o u n d a ry , c o n c a te n a te s e g m e n ts ...................................... 361
E r r o r c h e c k ............ ............. .............................. .................. .................. 363
C o m p le tio n of a r e a c e n tr o id c a l c u l a t i o n s ........................
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B u ild ID S r e c o r d s ................... ................ .. ....................................
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U p d ate M CB a n d w r ite D D S ......... .................. ........... .................... 364
E lim in a tio n of s m a l l f a c e s a n d l i n e s ................................. 365
M an u al E r r o r C o r r e c tio n (M EC) s u b s y s t e m .. . . . . . ......................
E r r o r l i s t i n g s .......................... ............................................................... 36 366
D e te rm in e c o r r e c tio n s , o p tio n a l p l o t .......................... .............
E r r o r c o r r e c tio n p r o g r a m (M EC M AIN)......................................
P h a s e 4 B ............ ..................................................................................................... 371
I n i t i a l i z a t i o n .................................................................. .......................... 372
R e a d new ID S an d IDS m a s t e r an d id e n tify b o r d e r r e c o r d s 372
P h a s e 5 .............................................................................. ................................... .. 373
373
I n i t i a l i z a t i o n ............................ ........... ............................................... .
R e a d in p u t a n d s to r e b o r d e r r e c o r d - c a lc u la te
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g e o d e tic s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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I n i t i a l i z a t i o n .............................................................
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a n d e q u iv a le n c e s in ta b le . A c c u m u la te g e o d e tic d a ta .
R e a d m a p b o r d e r f il e fo r fa c e . W o rk in g f il e of fram
ebods.
R e a d DDS m a s t e r f o r f a c e ...................................................................... 378
D e te rm in e e q u iv a le n c e w ith in f a c e .......................... .................... 378 378
W r ite d e le te in s tr u c tio n s f o r DDS m a s t e r . ...............................
C o m p a re a d ja c e n t d e s c r i p to r s . A s s ig n fa c e n u m b e r s ifequvalnt.
W r ite o u t ID S an d DDS fa c e n u m b e r ch a n g e in s tr u c tio n s . ...
C lo s e DDS m a s t e r f i l e .....................................................................
R e a d w o r k f il e of f r a m e b o r d e r s . W rite o u t f r a m e
368
380
369
P h a s e 7b o r d e r d e le te a n d ch a n g e i n s t r u c t i o n s .............................................................................................
381
R e a d in p u t f i l e s f o r e a c h f a c e.Initalzo........................................................... 3 8 1
E d it f i l e s f o r v a lid ity on a fa c e g ro u p b a s i s ............................
R e c a lc u la te g e o d e tic in fo rm aM
erg.tio n to b e m e r g e d ...................... 381 381
.
B
C
pdateM
U
a.
m
S
ritevsdD
W
309
Page
P h a s e 8 ..................................................................................... ..............................
In itia liz a tio n , c h e c k s e q u e n c e , a n d e d it f o r v a lid ity ............
R e a d f r a m e r e c o r d . R e a d fa c e a n d s e g m e n t r e c o r d
an d m a p b o r d e r e q u iv a le n c e r e c o r d .........................................................................................
C o m p a re s e g m e n t le n g th ...............................................................................
S p lit s e g m e n t . ............ .. . .............................................................
J o in m u ltip le e x t e r io r f a c e s ............................ ..............................
C opy a n d re m o v e d e le te d r e c o r d s . W rite out
re v ise d ID S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E n d p r o g r a m .............................................................................................
382
384
384
384
384
384
385
385
D a ta R e t r ie v a l S u b s y s te m .......................................................................................... 387
C o m m a n d L a n g u a g e I n t e r p r e t e r ....................................................... ...................... 391
S o u rc e p r o g r a m l i b r a r y (SYM LIB) . . . ......................................
R o u tin e p r o g r a m l i b r a r y (R T N L IB )..................................................
391
L o a d a b le l i b r a r y (L O D L IB )................. ......................................................... 391 391
E x a m p le s of r e q u e s t s ................... ....................................................................
C o m m a n d L a n g u a g e s ...................................................................................................... 395
M a n ip u la tio n la n g u a g e - #A SSESS c o m m a n d ........................................
A s s e s s m e n t la n g u a g e . ..........................................................................
M a n ip u la tio n la n g u a g e .....................................................................................
#O V E R LA Y .............................................................................. ..............
Plot............................................................................................................................................
E x a m p le s of O utput f r o m th e C a n a d a G e o g ra p h ic In fo rm a tio n
S y ste m . . . . . . . . . . . . . . . . . . . . . .
.
407
407
E x a m p le 1 - A r e a t o t a ls f r o m m a p s of s in g le d a ta t y p e .............. .
E x a m p le 2 - O v e rla y a n d c o m p a r is o n of m a p s of tw o
d iffe re n t d a ta t y p e s .
.
.
.
.
E x a m p le 3 - I d e n tific a tio n of la n d c h a r a c t e r i s t i c s a d ja c e n t
to s p e c ific f e a tu r e . P r o d u c tio n o f g ra p h ic
o u tp u t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- O v e rla y a n d c o m p a ris o n of m a p s of tw o
E x a m p le 4
d if fe re n t d a ta ty p e s
- M u ltip le o v e r la y s . W e ig h te d c o m p a ris o n s .
E x a m p le 5
L i s t a n d p lo tte d o u tp u t of s e le c te d a r e a s ......................
E x a m p le s of V -v a lu e A llo c a tio n , C lo u d E lim in a tio n , an d
B o u n d a ry T r a c in g . . . . . . . . . . . . . . . .
395
396
397
399
.
.
408
409
414
419
421
438
393
310
Page
P a r t i a l L i s t of P e r s o n s I n s tr u m e n ta l in th e D ev elo p m en t o f th e
C a n a d a G e o g ra p h ic In fo rm a tio n S y ste m in A p p ro x im a te O r d e r
of A p p e a ra n c e ...... .........
443
C a n a d a G e o g ra p h ic I n f o r m a tio n S y ste m B ib lio g ra p h y . ............................... 444
311
A P P E N D IX - LIST O F F IG U R E S
T itle
F ig .
Page
A. l a D a ta r e d u c tio n s u b s y s te m flow c h a r t ......................................................
319
A . lb D a ta r e d u c tio n s u b s y s te m flow c h a r t ( c o n tin u e d ) ...............................
320
A. 2
P h a s e 1 in p u ts a n d o u tp u ts ............................................................................
323
A. 3
P h a s e 1 flow c h a r t ....................................................................................
324
A.4
C o m p u ta tio n of V - v a lu e s ................................................................................
326
A.5
D ir e c tio n of lin e -fo llo w in g s c a n ("d") c o d e ) ....................... . ..............
327
A .6
D ir e c tio n o f s e c o n d h a lf o f lin e -fo llo w in g s c a n ..........................
328
A .7
C r e a tio n of g ap in o u tp u t im a g e ................................. ................................
331
A. 8
R e la tio n s h ip of a r e a s in tw o c o o rd in a te s y s t e m s ...............................
332
A. 9
C o n c e p tu a l fu n c tio n s of p h a s e 2 ..................................................................
333
A . 10 P h a s e 2 flow c h a r t ................................................................................ ...........
334
A . 11 In p u ts a n d o u tp u ts of p h a s e 3 ..................................................................
337
A . 12 P h a s e 3 flow c h a r t ............................................................................................
338
A. 13 C a llin g s e q u e n c e of ro u tin e s in p h a s e 3 . . ..........................................
339
A. 14 R e la tio n s h ip of u n it g r id s to u n it f r a m e s
.............................................
341
A. 15 S eq u en c e of f r a m e n u m b e r s .........................................................................
342
A . 16 M o rto n m a t r i x ............................ ....................................................................
343
A . 17 P h a s e 3 o p e r a tio n s
344
................................................................................
A. 18 C o lo u r e q u iv a le n c e r e s o lu t io n .....................................................................
344
A. 19 L in k a g e p r o c e s s ................................................................................................
345
A . 20 T r a n s f o r m a tio n s
............................ .............................................. ... G
apclosing.......................... 346
347
A . 21
Sin g le p o in t s m o o th in g ....................................................................................... 347
A. 22
T w o -p o in t sm o o th in g o r g e n e r a l i z a t i o n ................................................. 348
A. 23
Compacting................................................................................................................
350
A. 24
3 measurement area..........................................................................................
351
A. 25 Level
Structure of IDS and DDS..........................................................................................
354
A. 26
Phase 4A flow chart...................................................................................................
356
A . 27
Small noise face (interior)..........................................................................................
359
A . 28
A. 29
Small noise face (exterior).........................................................................................
360
312
F ig .
title
Page
A . 30 E lim in a tio n of v e r t i c e s a t s e c tio n b o r d e r s ...........................................
362
A . 31 E x t e r i o r a n d i n t e r i o r fa c e b o u n d a r ie s o f c o lo u r 8 .....................
362
A. 32 A com p o u n d e r r o r .............................. .................................................... ..
365
A. 33 D is to r tio n e r r o r in p h a s e 4 ........................................................................
365
A . 34 M EC s u b s y s te m flow c h a r t .........................................................................
367
A . 35 P h a s e 4B flow c h a r t .....................................................................................
372
A . 36 P h a s e 5 flow c h a r t ............................ ...............................................................
373
A . 37 C o n c e p t of m a tc h in g ..........................................................................................
374
A . 38 N o n -m a tc h in g v e r t i c e s a n d d e s c r i p t o r s ........................................
374
A . 39 F r a m e - a lig n e d s e g m e n t ...............................................................................
375
A. 40 P h a s e 6 flow c h a r t ............................................................................................
377
A . 41 E q u iv a le n c e s w ith in f a c e ................................................................................
378
A . 42 D e le tio n s in DDS m a s t e r f i l e .......................................................................
379
A . 43 M atc h in g o v e r f r a m e an d m a p b o u n d a r i e s .............................................
380
A. 44 P h a s e 7 flow c h a r t . . ..................................... ......................... .......................
38 1
A. 45 P h a s e 8 flow c h a r t ...........................................................................................
383
A . 46 J o in in g m u ltip le e x t e r i o r f a c e s ..................... ..................................
385
A. 47 S am p le o f IDS f o r m a t .......................... ..................................... .......................
386
A . 48 CGIS r e t r i e v a l m o n ito r s y s t e m ........................ ........... ....................
389
A . 49 C o n c e p tu a l d ia g r a m of #O V ERLA Y c o m m a n d f u n c t io n s .................
400
A. 50 F low c h a r t sh o w in g s e q u e n c e of lo g ic a l o p e r a tio n s in
ID S o v e r la y . . . . . . . . . . . . . . . . . . . . . . . .
401
A . 51 F lo w c h a r t sh o w in g s e q u e n c e o f lo g ic a l o p e r a tio n s in
DDS o v e r l a y . . . . . . . . . . . . .
404
A .52
OVQ p r o c e s s ........................................................................................................
405
A. 53 S o rtin g of f a c e e q u iv a le n c e r e c o r d ...........................................................
406
A. 54 E x a m p le 3 - CGIS g r a p h ic o u t p u t .............................................................
418
A. 55 R e c r e a tio n 605 - O r ig in a l m a n u s c r ip t c o p y ........................................
424
A. 56 A g r ic u ltu r e 205 - O r ig in a l m a n u s c r ip t co p y........................................
425
A . 57 F o r e s t r y 305 - O r ig in a l m a n u s c r ip t c o p y . .......................... ..
426
A . 58 W ild life U n g u la te s 405 - O rig in a l m a n u s c r ip t co p y .....................
427
A . 59 W ild life W a te rfo w l 505 - O r ig in a l m a n u s c r ip t c o p y ........................
428
A . 60 E x a m p le 5 - CGIS g ra p h ic o u t p u t .................................................
429
313
F ig .
T itle
Page
A . 61 In p u t m ap
438
A. 62 S c a n n e r o u tp u t
439
A. 63 R e s u lt o f V -v a lu e c a lc u la tio n s
440
A . 64 R e s u lt of c lo u d e lim in a tio n - f i r s t lin e
441
A . 65 R e s u lt of clo u d e l i m i n a t i o n - re m a in in g lin e s
442
314
A P P E N D IX - L IS T O F T A B L E S
T a b le
A. 1
T itle
C a n a d a G e o g ra p h ic In fo rm a tio n S y ste m - e x a m p le 1 .....................
A . 2 a C a n a d a G e o g ra p h ic I n f o r m a tio n S y s te m - e x a m p le 2 ....... ..
Page
408
410
A. 2b CGIS - e x a m p le 2 , c o n t i n u e d .............. ....................
411
A . 2c CGIS - e x a m p le 2, c o n t i n u e d ....................................................
412
A. 2d CGIS - e x a m p le 2, c o n t i n u e d ....................................................................
41$
A. 3 a C a n a d a G e o g ra p h ic In fo rm a tio n S y s te m - e x a m p le 3 ....................... 415
A . 3b CGIS - e x a m p le 3, c o n t i n u e d ....................................................................... 416
A . 3c CGIS - e x a m p le 3, c o n t i n u e d ...........................................................
417
A. 4
C a n a d a G e o g ra p h ic In fo rm a tio n S y s te m - e x a m p le 4 ..............
420
A. 5
W e ig h tin g f a c t o r s - e x a m p le s ...................................................................... 422
A . 6 a C a n a d a G e o g ra p h ic I n f o rm a tio n S y s te m - e x a m p le 5 ........................ 430
A . 6b CGIS - e x a m p le 5 , c o n t i n u e d ....................................................................
431
A . 6c CG IS - e x a m p le 5, c o n t i n u e d ....................................................................... 432
A . 6d CGIS - e x a m p le 5, c o n t i n u e d ....................................................................... 433
A . 6e CGIS - e x a m p le 5, c o n t i n u e d ...................................................................... 434
A . 6f CGIS - e x a m p le 5, c o n t i n u e d ............................ .......................................... 435
A . 6g CG IS - e x a m p le 5, c o n t i n u e d ................................. ..................................... 436
A . 6h CG IS - e x a m p le 5, c o n t i n u e d .............. ................................................... ..
437
315
A P P E N D IX
- T E C H N IC A L D E S C R IPT IO N O F T H E CANADA
G EO G R A PH IC IN FO RM A TIO N SYSTEM (CGIS)
T h is te c h n ic a l d e s c r i p tio n i s in te n d e d to allow th e r e a d e r f u lly to u n d e r ­
s ta n d th e fu n c tio n s of th e C a n a d a G e o g ra p h ic I n fo rm a tio n S y ste m , to
p r e s e n t e x a m p le s
of i t s p r o d u c ts , to d e s c r ib e th e o p e ra tio n s in v o lv ed in
a c h ie v in g e a c h fu n c tio n , an d to g iv e d e ta ils of th e a lg o r ith m s u n d e rly in g
th o s e o p e r a tio n s .
T h e s y s t e m Vs c u r r e n t ly in o p e ra tio n a t th e D e p a rtm e n t
o f th e E n v iro n m e n t, G o v e rn m e n t of C an a d a, O ttaw a.
D e ta ile d s y s t e m
d o c u m e n ta tio n a n d th e c o m p u te r p r o g r a m s r e s id e w ith th e D e p a rtm e n t o f
th e E n v ir o n m e n t.
s t a r t e d in 1961.
R e s e a r c h le a d in g to th e d e v e lo p m e n t o f th e s y s t e m
S in ce th a t tim e m o re th a n 40 p e r s o n s h av e b e e n a c tiv e
in i t s d e v e lo p m e n t.
F u ll ac k n o w le d g e m e n t of t h e i r e f f o r ts i s g iv e n a t th e
e n d of th i s te c h n ic a l d e s c r i p tio n an d in th e te x t.
T h e s y s te m i s c o n s id e r e d
to b e o p e r a tio n a l in t e r m s of th e fu n c tio n s d e s c r ib e d in th is a p p e n d ix in th a t
i t g e n e r a te s s u b s t a n ti a l p r o d u c ts f o r a d m in is tr a tiv e p u r p o s e s , f o r v a r io u s
l e v e ls of g o v e rn m e n t in C a n a d a .
T h e s y s t e m f a c i li tie s a r e , h o w e v e r,
u n d e r c o n tin u in g d e v e lo p m e n t.
DATA IN P U T SUBSY STEM
T h e d a ta in p u t s u b s y s te m c o n v e rts th e g r a p h ic s o u r c e d a ta to a s im p le
n o n -g ra p h ic f o r m a t.
T h r e e ty p e s of d a ta a r e e x tr a c te d f r o m e a c h s o u r c e
m a p : th e im a g e d a ta , th e d e s c r i p t o r d a ta , an d th e lin k a g e d a ta .
T h e im a g e d a ta a r e th e li n e s th a t f o r m th e b o u n d a rie s on th e o u te r ed g e
of th e m a p , p lu s a l l th e lin e im a g e s c o n ta in e d in i t s i n t e r io r .
T h is w eb
o f g r a p h ic d a ta i s t r a c e d (s c rib e d ) on a c le a n s h e e t.
T h e d e s c r i p t o r d a ta a r e w r itt e n d e s c r ip tio n s o f th e e le m e n ts th a t c o m p r is e
th e m a p , s u c h a s d e s c r i p tio n s o f th e p r e s e n t la n d u s e of e a c h in d iv id u a l
a r e a on a p r e s e n t - l a n d - u s e m a p .
E a c h d e s c r i p to r fo r e a c h in d iv id u a l m ap
e le m e n t i s s e q u e n tia lly n u m b e re d a n d l i s t e d on a f o r m d e s ig n e d f o r th e
p u rp o se.
T h e t h i r d ty p e of d a ta i s th e k e y to lin k in g th e im a g e d a ta to th e d e s c r i p to r
d a ta .
A t r a n s p a r e n t s h e e t i s o v e r la id on th e s o u r c e m a p and th e d e s c r i p to r
l i s t n u m b e r i s w r itt e n a t th e a p p r o x im a te c e n tre of th e m ap e le m e n t to
w h ic h e a c h d e s c r i p t o r r e l a t e s .
316
T h e s e th r e e s o u r c e m ap d e r iv a tiv e s a r e p a s s e d th ro u g h a d r u m s c a n n e r ,
a n X -Y d ig i tiz e r , an d an e n c o d e r , r e s p e c t iv e l y , a n d a r e l a t e r p u t on
m a g n e tic ta p e to f o r m th e in p u t to th e d a ta r e d u c tio n s u b s y s te m .
5.
D ia g ra m
11 in C h a p te r 5 ab o v e il l u s t r a t e s th e d a ta p r e p a r a tio n p r o c e s s .
T h e tr a c e d s h e e t of im a g e d a ta i s p la c e d on th e d r u m s c a n n e r an d th e
s c a n n in g o p e r a tio n p r o d u c e s a d ig itiz e d m a p o f th e im a g e on m a g n e tic ta p e .
T h e d ru m s c a n n e r w a s d e v e lo p e d to m e e t C a n a d a G e o g ra p h ic I n fo rm a tio n
S y s te m r e q u i r e m e n t s b y th e I n te r n a tio n a l B u s in e s s M ach in es C o m p an y
(IBM ).
U se of th e d ru m S can n in g a p p ro a c h w a s f i r s t c o n s id e r e d in 1963,
d e s ig n c r i t e r i a w e r e e s ta b lis h e d b y th e a u th o r i n 1964, a n d d ev e lo p m en t
w o rk w a s c o n tr a c te d to th e fo llo w in g y e a r .
T h e s c a n n e r c o n s is ts of a
c y lin d r ic a l d r u m on w h ich a m a p o r c h a r t c a n b e m o u n te d , an d a m o v a b le
c a r r i a g e th a t slo w ly m o v e s th e s c a n n in g h e a d a c r o s s th e f r o n t of th e
r e v o lv in g d ru m .
T h e s c a n n in g s y s t e m c o n s is ts of th e s c a n n in g h e a d , i t s
a s s o c ia te d e l e c tr o n i c s , a n d c o n tr o ls le a d in g to a s ta n d a r d IB M m a g n e tic
ta p e d r iv e .
T h e te c h n iq u e e m p lo y e d i s to d e te c t c h a n g e s in in te n s ity of
lig h t r e f l e c te d f r o m b la c k or w h ite a r e a s on th e m a p s u r f a c e , an d to r e c o r d
th i s in fo rm a tio n a s a s e r i e s o f b in a r y b i t s w r i t t e n o n m a g n e tic ta p e .
The
s c a n h e a d u s e s f ib r e o p tic s an d ca n s c a n e ig h t s c a n li n e s s im u lta n e o u s ly .
T h e d r u m s c a n n e r c a n a c c e p t a m a p of up to 48 in . x 48 in .
A f u ll - s i z e d
m a p ta k e s a p p ro x im a te ly 15 m in u te s to s c a n , in c lu d in g th e tim e to m o u n t
a n d d is m o u n t i t , a n d s m a l le r s h e e ts ta k e a c o r r e s p o n d in g ly s h o r t e r tim e .
I t i s n o t w ith in th e s c o p e o f th i s ap p e n d ix to g iv e a d e ta ile d d e s c r ip tio n of
th e d r u m S c a n n e r; th e e n g in e e rin g a s p e c t s of th e d e s ig n h a v e b e e n d e s c r ib e d
b y T h o m p so n . 1 H o w e v e r, th e f o r m a t of th e m a p im a g e d a ta o n ta p e i s
p e r tin e n t.
O ne m a p -im a g e r e c o r d is p ro d u c e d f o r e a c h 0 .0 3 2 in . alo n g th e
X a x is of th e m a p s h e e t, an d th e h e ig h t of e a c h r e c o r d i s 0 .0 0 4 in . a lo n g th e
Y a x is .
T h e 0 .0 3 2 in . r e c o r d , c o m p r is in g one b y te of c o m p u te r s to r a g e ,
i s d iv id e d in to e ig h t b it s .
w id e .
E a c h b it th u s r e p r e s e n t s a n a r e a o r sp o t 0 .0 0 4 in .
L in e s d ra w n on th e m a p a r e u s u a lly 0 .0 0 8 in . w id e.
T h e a d v a n tag e
of s c r ib in g a s o p p o s e d to tr a c in g b y p e n c il o r p e n i s th a t th e m in im u m lin e
w id th c a n b e a s s u r e d w ith o u t e x c e s s iv e lin e th ic k n e s s .
If th e s c a n h e a d s
id e n tify 50% o r m o re of a s p o t a s p a r t of a li n e , th e n th e b it g e n e ra te d is
1; i f n o t, th e b it g e n e ra te d is 0.
1. T h o m p so n 1967.
In th i s m a n n e r , a lin e i s r e p r e s e n t e d a s
317
a c o lle c tio n of 1 - b its , w h ich a r e u s u a lly 1, 2, o r 3 s p o ts in w id th .
T h e s c r ib e d im a g e s h e e t, w ith th e t r a n s p a r e n t n u m b e re d o v e r la y s u p e r ­
im p o s e d , i s p la c e d on a D -m a c c a rto g r a p h ic X -Y d ig itiz e r w ith th e f o u r
c o r n e r r e f e r e n c e p o in ts an d th e c o o r d in a te s o f one r e f e r e n c e p o in t p e r
m a p " f a c e " c o d e d in d ig its .
A m a p f a c e i s an y one of th e d is tin c t a r e a s
th a t to g e th e r m a k e up th e s u r f a c e of th e m a p .
T h e m a g n e tic ta p e f r o m th e X -Y d ig itiz e r i s th e n p la c e d on a n N CR e n c o d e r
a n d th e s e q u e n tia lly n u m b e re d d e s c r i p to r d a ta a r e e n c o d ed b e s id e th e
a p p r o p r i a te r e f e r e n c e c o o r d in a te s . T h e s e tw o p r o c e s s e s a r e d u p lic a te d to
allow f o r v a lid ity c h e c k s in th e f i r s t p a r t o f th e d a ta r e d u c tio n s u b s y s te m .
D A TA R ED U C TIO N SU BSY STEM AND
M ANUAL E R R O R C O R R EC TIO N SUBSY STEM
T h e d a ta re d u c tio n s u b s y s te m a c c e p ts th e r e c o r d s p ro d u c e d b y th e s c a n n e r ,
d ig i tiz e r , a n d e n c o d e r a n d , in c o n c e r t w ith th e m a n u a l e r r o r c o r r e c tio n
(M EC) s u b s y s te m , tr a n s f o r m s th e m in to a c o m p a c t, e r r o r - f r e e f o r m a t
th a t i s c o n v e n ie n t f o r s to r a g e a n d s u b s e q u e n t c o m p u te r p r o c e s s in g .
" L o g ic a l o p e r a tio n s " a r e th e s te p s ta k e n to c a r r y out th e w o rk ; in th e d a ta
r e d u c tio n s u b s y s te m th e y a r e g ro u p e d in to " p h a s e s " .
E a c h p h a s e is a s e t
of g e n e ra lly r e l a t e d lo g ic a l o p e r a tio n s , a n d h a s a s e t of in p u ts th a t it
o p e r a t e s u p o n o r r e f e r s to an d a s e t of o u tp u ts th a t it p r o d u c e s f o r u s e b y
su b se q u en t p h a s e s .
T h e s e p h a s e s a n d lo g ic a l o p e r a tio n s a r e th e b u ild in g
b lo c k s w ith w h ic h it i s p o s s ib le to d e s c r i b e a s y s te m .
T h e c o m p u te r i t s e l f
re s p o n d s to a s e r i e s of p r o g r a m s , m a d e up of ro u tin e s an d s u b r o u tin e s ,
w h ic h w o rk w ith i t s ow n r e s id e n t o p e r a tin g s y s t e m an d ta k e ad v a n ta g e o f i t s
s p e c if ic c o m p u te r a r c h i te c tu r e .
O c c a s io n a lly a lo g ic a l o p e r a tio n is h a n d le d
b y a s in g le p r o g r a m , b u t n o r m a lly i t r e q u i r e s th e u s e of s e v e r a l p r o g r a m s ,
ro u ti n e s , o r s u b r o u tin e s , s o m e o r a l l of w h ic h m a y a ls o b e u s e d f o r o th e r
lo g i c a l o p e r a tio n s .
In 1969, th e a c tu a l p r o g r a m d e s c r ip tio n f o r th e C a n a d a
G e o g ra p h ic In f o rm a tio n S y ste m r e q u i r e d a s u b s ta n tia l am o u n t (19 v o lu m es)
of d o c u m e n ta tio n .
S in ce th a t ti m e , p r o g r a m s h a v e b e e n m o d ifie d an d f u r t h e r
p r o g r a m s h a v e b e e n w r itte n .
lo p m e n t.
T h e s y s t e m c o n tin u e s to b e u n d e r a c tiv e d e v e ­
A c c o rd in g ly , th i s p a r t of th e ap p e n d ix w ill c o n c e r n i t s e l f w ith
b r i e f l y d e s c r ib in g th e s u b s y s te m in t e r m s of th e lo g ic a l o p e r a tio n s c a r r i e d
318
out b y e a c h p h a s e .
T h e n a m e s o f p r o g r a m s a n d r o u tin e s in v o lv e d w ill b e
g iv e n w h e r e a p p r o p r ia te .
A flow c h a r t of th e d a ta re d u c tio n s u b s y s te m i s p r e s e n t e d b elow a s a g u id e
to th e flow o f d a ta th r o u g h th e p h a s e s .
A lthough i t p ro v id e s o n ly a b r ie f
in d ic a tio n of th e o p e r a tio n s w ith in e a c h p h a s e , i t g iv e s a p ic tu r e o f th e
d a ta th a t e n t e r e a c h p h a s e , th e d a ta p ro d u c e d b y e a c h p h a s e , a n d th e
lin k a g e s b e tw e e n p h a s e s ; it m a y th u s o f f e r a r e f e r e n c e p o in t f o r th e d e s c r i p ­
ti o n s of in d iv id u a l p h a s e s .
In g e n e r a l, p h a s e s a r e lin k e d b y " s o r t s " , b y w h ich th e p h a s e o u tp u t is
r e a r r a n g e d in to a c o n v e n ie n t f o r m a t f o r th e n e x t p h a s e .
s o m e w ay o f r e p o r t in g e r r o r s .
E ach p hase h as
In p h a s e s 1 to 4A , th e ty p e s o f e r r o r s to b e
r e p o r t e d a r e s p e c if ie d on a " d ia g n o s tic c a r d " .
T h e e r r o r s a r e t r a c e d an d
r e c o r d s of th e m a r e p r in t e d o u t a t th e e n d of e a c h p h a s e o n a " s y s t e m
m e ssag e s" lis t.
S p e c ia l p r o c e d u r e s a r e b u ilt in to th e p r o g r a m s to r e p o r t
u p o n a n d r e s o lv e d a t a e r r o r s .
A s e a c h m a p i s p r o c e s s e d th ro u g h th e s y s t e m , v it a l s t a t i s t i c s ab o u t i t s
s i z e , c o m p le x ity , e r r o r s t a t e , a n d s o f o r th a r e l i s t e d on a m a p c o n tr o l
b lo c k (M CB).
T h is i s p a s s e d f r o m p h a s e to p h a s e r a t h e r lik e a n o te b o o k .
E a c h p h a s e u s e s th e d a ta i t c o n ta in s to p r e p a r e th e a p p r o p r i a te - s iz e d f i l e s ,
ta b le s , o r s w itc h e s f o r p r o c e s s in g , o r e x t r a c ts m a p c o n s ta n ts f r o m it f o r
u s e in c a lc u la tin g c h a n g e s of m a p p r o je c tio n o r s c a l e , a n d s o on.
T o w a rd
th e e n d of th e w o rk , in p h a s e 6, th e p r o c e s s in g of in d iv id u a l m a p s g iv e s
w a y t o th e p r o c e s s in g o f a l l m a p s a s o n e u n it.
A t th is p o in t th e M CB i s jo in e d
b y th e m a s t e r c o v e ra g e c o n tr o l b lo c k (M CCB), w h ic h a c ts a s th e n o te b o o k
f o r a l l th e m a p s in th e d a ta b a n k of o n e d a ta ty p e (fo r e x a m p le , la n d u s e ,
c e n s u s , o r r e c r e a t i o n p o te n tia l).
T h e M CCB r e c o r d s a r e u s e d in th e s a m e
m a n n e r a s th e M CB r e c o r d s , b u t r e f e r to th e e n t i r e d a ta b a n k in i t s f in a l
f o r m a t.
It c a n b e s e e n f r o m th e flow c h a r t th a t in p h a s e 0 th e d a ta a r e a c c e p te d f r o m
th e d ig i tiz e r a n d e n c o d e r a n d e d ite d f o r v a lid ity a n d c o n s is te n c y .
T h ese
d a ta a r e th e n u m b e re d r e c o r d s th a t d e s c r ib e th e m a p e le m e n ts , a n d th e
s i m i l a r l y n u m b e re d r e f e r e n c e c o o r d in a te s th a t allow e a c h d e s c r i p tio n to b e
r e l a t e d to a p la c e on th e m a p .
319
Scanner
Digitiser
Encoder
Control cards
Digitizer and
atddescriptor
Scanner tape
hase0rolit System messages
P
PHASE 0
Edit and verify
inputdat
Diagnostic card
ase1rolit System messages
P
PHASE 1
Image data reduction
Identify and code
map elements
Map control
M
B
C
block
Work files
E
diteddigitizer and
descriptor
d a t a
Diagnostic ca rd
Error data file
PHASE 2
inesegmenttape
L
enbtw
ions
cordinatesymCalculate transformat
List of equivalent
colours
System messages
Phase 2 error list
descriptor
igrnd data
hase2outpD
P
ortby section
S
MCB
Map controlblock
Sorted phase 2
output
Digitizer and
descriptor data
PHASE 3
Correlate image and
descriptor data
Eliminate distortions
Compact Image data
Diagnostic card
System messages
Phase 3 error list
Temporaryw
orkfile
IDS
Master
has3output
ortedP
S
Diagnostic card
PHASE4ACreatedatabankform
atTopological
errordetection
hase4rolitSystem messages
P
Phase 4
D
F ig . A. l a .
D3
CORRECTION
M
O
R
E
L
U
N
A
SUBSYSTEM
D a ta r e d u c tio n s u b s y s te m flow c h a rt.
blockMap control
B
C
M
320
Phase 4
DOS
PHASE 4B
Identify and list
border data for edge
match process
Sort
by map
DDS
r IDS
ste
a
M
Master
MCB
Map control
block
PHASE 5
Primary edge match
Resolve border
segment equivalences
System messages
Phase 5 error list
Faceandborder
data J
Sort
by face #
Combined
phase 4 lDS'
r DOS
ste
a
M
Sorted
face and borderd
a
t
MCB
Map control
PHASE 6
Secondary edge match
Resolve face equivalences
Generate update data
Equivalent
face andborderd
t
a
MCCB
Master coverage
control block
S
DDS
d
rte
o
updated
t
a
P
litSystem messages
ro
6
se
a
h
Sort
IDS Master
PHASE 8
Update IDS
Sort
by face #
DDS Master
Sorted
equivalences
S
DDS updatedata
d
rte
o
MCCB
Master coverage
control block
UpdateP
7 DDS
se
a
h
System messages
Phase 7 error list
System messages
Phase 8 error list
IDS Master
visd
e
R
MCCB
Master coverage
control block
DDS Master
F i g . A. lb. D a ta r e d u c tio n s .u b sy ste m flow c h a r t (continu ed ).
321
In p h a s e 1, th e ra w im a g e d a ta a r e a c c e p te d d ir e c tl y f r o m th e s c a n n e r .
T h is la r g e am o u n t of d a ta i s e x a m in e d p ie c e b y p ie c e , th e g r a p h ic e l e m e n ts
(lin e s , in t e r s e c ti o n s , m a p b o r d e r s , e t c .) th a t m a k e up th e m a p a r e id e n tifie d
and la b e lle d , and th e r e s t is r e je c te d .
P h a s e 2 p r e p a r e s th e w ay f o r b rin g in g th e d e s c r i p to r d a ta an d th e im a g e data,
to g e th e r .
B e c a u s e th e y w e r e p ro d u c e d on d if f e re n t in p u t d e v ic e s , th e y
a r r i v e f o r p r o c e s s in g w ith in h e r e n tly d if f e re n t f r a m e s of r e f e r e n c e .
The
c o o rd in a te s y s t e m o f th e s c a n n e r d a t a m u s t th u s b e p u t in to a f o r m th a t
ca n b e r e l a t e d to th e c o o rd in a te s y s t e m of th e d a ta f r o m th e d ig itiz e r ,
s p e c if ic a lly th e r e f e r e n c e c o o rd in a te s an d t h e i r r e l a t e d p ie c e s o f d e s c r i p t o r
d a ta .
T h e tr a n s f o r m a tio n s n e c e s s a r y to a c h ie v e th i s a r e c a lc u la te d in p h a s e
2.
P h a s e 3 b r in g s th e d a ta to g e th e r .
In e ff e c t, th i s i s th e f i r s t tim e in th e
s u b s y s te m th a t th e s o u r c e m a p i s r e c r e a t e d .
O nce th e d a ta a r e a s s e m b l e d
in p h a s e 3, d is to r tio n s c a n b e e lim in a te d a n d th e r e c o r d s c o m p a c te d to an
e c o n o m ic a l le v e l f o r f u r t h e r h a n d lin g .
P h a s e 4A i s a n o th e r m a jo r p h a s e .
It ta k e s th e c o m b in e d r e c o r d s f r o m p h a s e 3 a n d f r o m th e m a s s e m b le s th e
im a g e f ile o r " im a g e d a ta s e t" (IDS), a n d th e d e s c r i p t o r f ile o r " d e s c r i p to r
d a ta s e t" (DDS), in th e s a m e f o r m a t a s th a t o f th e fin a l d a ta b an k .
T h e d iff e re n t d a ta r e c o r d s h a d to b e b r o u g h t to g e th e r in p h a s e 3 s o th a t th e
im a g e an d d e s c r i p to r co u ld b e m a tc h e d p r o p e r l y .
Now it i s co n v e n ien t to
s e p a r a t e th e m , b e c a u s e th e r e t r i e v a l p r o c e s s e s th a t e v e n tu a lly o p e r a te o n
th e im a g e f il e n e e d n o t b e b u r d e n e d w ith th e d e s c r i p t o r d a ta , and s i m i l a r l y
th e r e t r i e v a l p r o c e s s e s th a t e v e n tu a lly o p e r a t e o n th e d e s c r i p to r d a ta w o r k
im m e a s u r a b ly f a s t e r if th e y a r e n o t r e q u i r e d to r e t a i n th e im a g e d a ta .
P o in te r s f r o m one file to a n o th e r allow jo in t p r o c e s s in g a s d e s ir e d .
P hase
4A th e r e f o r e in v o lv e s b u ild in g lin k a g e s b e tw e e n th e c o m p o n e n ts o f th e m a p ,
a n d a llo w s a d e ta ile d to p o lo g ic a l c h e c k to b e m a d e of th e m a p c o m p o n e n ts
a n d a li s t in g o f e r r o r s to b e p u t o u t f o r c o r r e c tio n .
T h e se p r o c e s s e s a r e
h a n d le d b y th e m a n u a l e r r o r c o r r e c tio n s u b s y s te m , w h ich r e c y c le s th e
c o r r e c tio n s th ro u g h p h a s e 4A u n til a c le a n s e t of new m a p d a ta i s a c h ie v e d .
P h a s e s 4B to 8 a r e in v o lv e d w ith a lig n in g th e e d g e s of th e new m a p s b e in g
p r o c e s s e d w ith th o s e a l r e a d y in th e d a t a b a n k (th e e d g e -m a tc h p ro b le m ).
P h a s e 4B is to id e n tify an d l i s t th e r e c o r d s th a t f a l l on th e b o r d e r s a n d m u s t
322
b e m a tc h e d .
P h a s e s 5 an d 6 a r e a tw o - s ta g e ed g e m a tc h in g p r o c e s s ; p h a s e
5 o p e r a tio n s m a k e s u r e th a t th e d e s c r i p to r s on b o th s id e s o f th e in te r f a c e
a r e a lig n e d , a n d th e p h a s e 6 p r o c e s s t r a c e s th e e n tir e b o u n d a r ie s o f sin g le
a r e a s th a t m a y f a l l a c r o s s th e in te r f a c e , and m a k e s s u r e th a t th e y h a v e th e
s a m e d e s c r i p to r .
A s e t of in s tr u c tio n s i s a ls o p r e p a r e d f o r c h a n g e s th a t
h a v e to b e m a d e to b o th th e new d a ta s e t an d th e m a s t e r d a ta s e t , to m a k e
th e m c o m p a tib le .
Som e of th e s e c h a n g e s a r e c a r r i e d out in p h a s e 7, a n d th e
new d e s c r i p to r r e c o r d s a r e a d d e d to th e m a s t e r d e s c r i p to r d a ta s e t.
O th e r
c h a n g e s a r e c a r r i e d o u t in p h a s e 8, a n d th e new im a g e d a ta r e c o r d s a r e
a d d e d to th e m a s t e r im a g e d a ta s e t.
A fu ll d e s c r ip tio n of th e lo g ic a l o p e r a ­
tio n s w ith in e a c h p h a s e i s g iv e n b elo w .
Phase 0
In p h a s e 0 , th e in p u t d a ta f r o m th e d ig itiz e r a n d e n c o d e r a r e e d ite d f o r
v a l