Symbology
The guts of
making a decent
map!
1
What’s in the module?
• explore a GIS map and get information about map
features
• preview geographic data and metadata
• add data to a map
• describe the structure of a GIS map
• explain how a GIS represents real-world objects
• change the way features are drawn on a map
• access feature information in different ways
• describe spatial relationships of map features
• describe how GIS can be used to solve problems
2
What is important in the module?
• explore a GIS map and get information about map
features
• preview geographic data and metadata
• add data to a map
• describe the structure of a GIS map
• explain how a GIS represents real-world objects
• change the way features are drawn on a map
• access feature information in different ways
• describe spatial relationships of map features
• describe how GIS can be used to solve problems
3
And imbedded in there is …
• Information on how to decide…
– what you want to communicate to whom.
– On the kind of classification to use to do
that
• That’s why you need to read the stuff
in the text and think about what you
are doing in module 2.
4
An Important Concept
• “Many Factors affect the colors you
choose.
• The perceptual structuring of the
colors should correspond with the
logical structuring in the data…
• Make sure the character and
organization of the colors match the
logic of your data…”1
1
Cynthia Brewer, Designing better maps. ESRI Press
5
And…
• “When choosing map colors
– you should not be overly concerned about
which colors your audience likes. Everyone
has an opinion …
– It does seem that most people like blue and
do not like yellow.
– People like maps with many colors so focus
your attention on presenting your data clearly
using YOUR favorite colors.”1
1
Cynthia Brewer, Designing better maps. ESRI Press 6
And…
• “When choosing map colors
– you should not be overly concerned about
which colors your audience likes. Everyone
has an opinion …
– It does seem that most people like blue and
do not like yellow.
– People like maps with many colors so focus
your attention on presenting your data clearly
using YOUR favorite colors.”1
1
Cynthia Brewer, Designing better maps. ESRI Press 7
However
• Usually students don’t have to much
trouble with making decent maps with
reasonable symbolizations
• It comes naturally
• But you do need to keep some things
straight when working with
classifications of data
• And you usually have to classify
8
• Nominal
Data Types
– are categorical data where the order of the
categories is arbitrary
• Ordinal
– categorical data where there is a logical
ordering to the categories
• Interval
– continuous data where differences are
interpretable, but where there is no "natural"
zero
• Ratio
– continuous data where both differences and
ratios are interpretable
9
….more
• Quantitative data is numerical
–
–
–
–
–
Ratio, Interval, ordinal data types
continuous data
you are not limited to acuity of the eye
depth-to-bedrock (ratio)
Water table, pollution conc.
• Qualitative data is not necessarily
numeric
– Nominal data – soil type, road classification
– limited to max of 10-12 colors (classes) and you
want contrast – 5 is better yet
10
Which on works better?
Depends on the
purpose of the
map
11
Symbols
• Lots of symbols for points, lines, &
polys
• Labeling features –
– Dynamic and Interactive
– Annotation
• Symbolizing based on attribute
– Category
– Quantity
12
Quantity
• Graduated colors
– Color ramps – which work best?
• Graduated Symbols (classification)
• Editing legend entries for the TOC
13
Classification
• How many classes
• What method to use for placing the
values into classes
• What kind of symbology to use (e.g.,
graduated colors or graduated
symbols)
14
Maps - Categorical
• Categorical symbolization is typically
used for NOMINAL data
– Quite often similar colors will be used
for related categories
– You want the user to be able to discern
the categories
15
Quantitative maps
• Displays quantitative data – interval
or ratio data and even ordinal data
• A graduated ramp or palette is used
16
Classifications
• Natural breaks : finds groupings
inherent in the data. Default
• Equal interval : interval between each
class is the same.
• Quantile : each class contains an
equal number of values (features).
• Manual : you decide
17
18
The Well Designed Map…
• Has a single purpose!
• Size of paper and map scale determine the
level of detail
• You cannot simply blow up a map from 8.5-11 to
something that would hang on the wall.
• A small map size will limit detail
• A large map viewed from a distance has same problem
• Reader must be able to easily interpret
features
• Reader should be able to instantaneously
understand the maps message
19
Too Much White Space!
420000
440000
460000
480000
LEWIS COUNTY
NEW YORK
500000
4880000
4880000
US Highway
[
%
[ [%
%
4860000
[%%
[%
[%
[ %
[ %
[
[%
[%
%
[
[
%
State Highway
[
%
4860000
Sub Station
[
%
Rivers
[
[ %
%
No Placenames
4840000
N
4840000
[
%
W
[
[%
[ %
[ [% %
%
[%
%
[[
%
ArcView Export
4820000
screw up in 8.3!
Only went to 3000
480000
500000
m in Layout!
[
%
4820000
E
S
[
%
420000
30000
440000
460000
0
30000
This map to be used to evaluate
sites for future paper plant which
has to be near a substation
and a highway.
60000 Meters
LAGIS, esf
20
The elements one-by-one
• Title
– Draws attention by virtue of its size (big!)
– Focuses attention on primary purpose of
content of map
– Not always needed
• Legend
– Principle reference to symbology
– MUST be there (usually)
21
The elements one-by-one
• Scale
– A MUST!
– Types
• graphic -- the bar
• verbal -- 1” = 1 mile (watch this one)
• a ratio 1/24,000 (this one too)
– Because of ubiquitous nature of Xerox
machines the graphic scale is a must,
the others are optional
22
The elements one-by-one
• Credits
– another, older, term for metadata
– Some metadata can be placed on map
• Data source
• Statement of accuracy, both spatial and
attribute
• Date data collected, date map made
• Your name, assignment # etc…
23
The elements one-by-one
• Credits
– another, older, term for metadata
– Some metadata can be placed on map
• Data source
• Statement of accuracy, both spatial and
attribute
• Date data collected, date map made
• Your name, assignment # etc…
24
The elements one-by-one
• Mapped and unmapped areas
– Objects, land, water, and other
geographical features important to the
purpose of the map
– makes the composition a map rather than
a diagram
– The most prominent map element
• Graticule & Grids
– Graticule – geographic coordinates
25
The elements one-by-one
• Borders and neatlines
– Borders serve to restrain eye movement and
focus attention on the map. A Border
surrounds all the elements of a map.
– A fill color can substitue for a border
– Neatlines are:
•
•
•
•
finer than borders
drawn inside borders
mainly decoration
Used to highlight objects (like legends) and to help
balance a map
26
Composition: Planar Organization
• Balance
– visual impact of arrangement
• is the map “heavy” at top, bottom, sides???
Visual center:
5% of total
height above
Geometric center -Arrange content
around
this point
Geometric
center
27
Visual weight
• Depends on location
– obj weight increases with distance from center
– obj at top are heavier than those at bottom
– obj on right are heavier than those on left
• Depends on size (Duh!)
• Depends on color, interest, and isolation
– Red>Blue, Bright>dark
– complex > simple
– isolated > groups
• For Example …
28
Which is better balanced?
29
Which is better balanced?
30
Movement of reader’s eye - upper left to lower right
Focus
Field
31
Using Eye Movement
Eye goes left to right
Generally you want the reader to see the map
BEFORE seeing the legend – can’t always do it
32
•St. Louis too far from
visual center, balance
not bad, however
•Hard to read name
Better, but a heavy on right
Balance with legend etc.
33
Location of St, Louis
Legend
-adf asdf
adfafffdsf
34
Location of St, Louis
Don’t
really need
since
countries
are labeled
35
Size / white space problems
Is this a better balanced
map?
36
Summary of Guidelines
1) Map layout – where are the pieces going to go
– major pieces – visual center – eye path –
uneven juxtaposition of parts
a)
b)
c)
d)
e)
The map area and what’s in it
Legend placement (usually to right of map)
Scale bar, North Arrow
Balance
White space
2) Map Title – Large – may not be needed
37
Summary of Guidelines
3) Credits (Metadata) usually present
4) For FOR357/557- Author’s name,
Exercise #, & date!
5) Borders and neatlines.
a) Border around ALL map pieces or solid fill
b) Neatlines (or fill) around (in) various pieces
6)
Color – tricky – but not garish!
38
Booby Trap
•
•
•
•
When you make scale bar it is grayed out?
Why
You didn’t set map and distance units
No map units then ArcGIS has no idea
what they are – probably no metadata
• If map units are m and you don’t want scale
bar in meters then you have to set the
distance units
39
Summary
• I have just covered the tip of the ice berg
regarding symbols, color, and map design
• Even without intensive instruction in map
design students tend to make decent
designs
• Main problems are:
– White space
– Borders
– Location of TOC
40