Maps, Map Projections and
Reading Maps
Richard Knight
Available at http://planet.uwc.ac.za/nisl/gis
Maps can be prepared on many forms
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Earliest portable form would have been drawn on parchment
Linen
Paper
Plastic/Mylar
What data do maps provide us?
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Date / Publisher / Printer
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Scale / direction /
Distance / ratios
Geographical Position
Coordinates/ projection
Features / places / legends
Other information?
You can classify maps into the following types

Topographical: Represents objects such as roads,
rivers, coastline
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Thematic: Represents themes such as soil types
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Chloropleths: Represents interpreted boundaries
e.g. census
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Isopleth: Represents imaginary lines with “equal
value” e.g. contours
All maps will
provide you with
a Arrow
indicating both
truth North (the
precise top axis
of the earth’s
spheroid) and a
magnetic north
which indicates
where our
compasses will
point to as north
North Pole
Magnetic
North Pole
Magnetic
South Pole
South Pole
For global represented of
position we use degrees of
Latitudes (parallels) and
Longitude (meridians). The
largest in length degree of
latitude is the equator and forms
the base line for measurements
of degrees of latitude which
increase until you reach the
north or south pole at which
point a right angle has been
formed (hence the poles are 900
latitude). At 23.5 north and
south latitude the tropics of
Cancer and Capricorn occur
respectively.
N
Tropic
of Cancer
23.50
0
90
S
Equator
In contrast to these
degrees of latitude
which become
smaller the
degrees of
longitude inscribe
the same-sized
circumferences but
do not lie parallel
to each other
Distance
A-a > B-b
A
B
a
b
N
900
Cylindrical projections
are derived from
projecting a spherical
surface onto a cylinder.
For example if you took
you’re orange and
wrapped an A4 sheet of
paper around it. The
paper can be arranged
around the orange in a
variety of arrangements
A Tangent Projection
would result if you
wrapped your paper
vertically so that the
cylinder was parallel to the
meridians (lines of
longitude).
Area: Many map projections are
developed to be an equal area
representation of the real world but
distort spatial information in some way
or another . Shape, direction or scale
are distorted in order to achieve the
equal area criteria. Albers and
Azimuthal Lambert and are equal area
conic projections.
Shape: Projections which represent the
shape of features are referred to as
conformal. Conformal projections
usually maintain the accuracy of relative
directions. Most large-scale maps are
prepared using conformal projections.
Lambert conformal conic is a good
example of this projection.
Distance: Projections which correctly
represent the lengths between two
points are referred to as equidistant.
Equidistant projections are useful for
calculating and summarizing lengths
and perimeter measurements of
features
Direction: Projections which correctly
depict directions (azimuths) between
points on the map and its centre are
referred to as azimuthal. These
projections will distort one of the other
maps parameters, but will represent all
routes from the centre to other points as
straight lines. Mercators projection work
on these assumptions and are derived
from estimates based on cylindrical
estimates.
Cylindrical projections
In the secant case, the cylinder
touches the sphere along two
lines, both small circles (a circle
formed on the surface of the
Earth by a plane not passing
through the center of the Earth).
Cylindrical projections
When the cylinder upon which the sphere is projected
is at right angles to the poles, the cylinder and
resulting projection are transverse.
Cylindrical projections
When the cylinder upon which
the sphere is projected is at
right angles to the poles, the
cylinder and resulting
projection are transverse.
Cylindrical projections
When the
cylinder is at
some other, nonorthogonal,
angle with
respect to the
poles, the
cylinder and
resulting
projection is
oblique.
The Mercator projection is one of the best known
and has straight meridians and parallels that
intersect at right angles. Scale is true at the
equator or at two standard parallels equidistant
from the equator. This projection seriously
distorts distances and areas.
The Universal Transverse Mercator (UTM) is
probably the best known projection system for
displaying large surfaces of the earth since it
provides high levels of precision. To minimize the
distortion the cylinder is wrapped around the earth
transversely and is place at 60 of rotation East and
West of 1800 meridian for each hemisphere.
Consequently 60 zones north and 60 zones south
are generated and are numbered eastward from the
1800 meridian. Cape Town lies in the 34th Zone and
is referred to as UTM 34S. The UTM system is only
applied from 840 North to 800 South Latitude.
Conic projections which
result from projecting a
spherical surface onto a
cone. When the cone is
tangent to the sphere
contact is along a small
circle such as a latitude.
You can view this by
twisting your A4 sheet into
a cone and placing over
the orange.
Albers Equal Area Conic
projection allows areas to
be proportional and
directions true in limited
areas but distorts scale and
distance except along
standard parallels. This is
one of the most common
projection used to map
large countries where the
east-west distances are
greater than the north-south
extent (e.g. USA and
Russia). It is often used to
represent South Africa.
Azimuthal or Planar
projections are where a
flat sheet is placed in
contact with a sphere, and
points are projected from
the sphere to the sheet.
You can do this by taking
your A4 sheet and
pressing it against the
orange.
NON-PROJECTIONS
Plane: (Cartesian) - not a projection but truth to
earth surface - data may be stored in this form, but
it is not good for accurate measurements of
distance e.g. metres.
Datums
While we often refer to the earth as a sphere, it is more
correctly referred to as a geoid (defined as a hypothetical
surface of the earth that corresponds to mean sea level).
The earth is not a sphere since it is flattened at both poles
and bulges at the equator. In addition there are significant
bulges and depressions on the surface. The are hundreds
of different datums which have been used to estimate the
size (areas and distances) of features on the earth. Datums
have evolved from those describing a spherical earth to
ellipsoidal models derived from years of satellite
measurements.
To best describe this geoid mathematically, we use
reference ellipsoids to approximate the size and
shape of the earth.
Lets look at a Map - Saldanha Bay
The name is 3217DD, what does this mean? The
32 refers to the degrees South and the 17 to
degree East, these two numbers define the top left
corner of a one minute by one minute grid on the
surface of the earth. This grid square can then de
divided into four quarters each representing 30
minute by 30 minutes grids and from the top left
are label A, B, C and D respectively. Each of
these half-degree grids are in turn divided into
quarters and they to are labeled A, B, C and D
respectively.
Consequently we have divided our grid into sixteen
quarter degree grids and can be represented as
follows:-
A
C
A
A
B
A
D
C
B
A
C
C
B
B
D
B
D
D
C
D
Colour is 153 0 0 Font is 24~36 point Arial Shadow
 Dark green font Arial at least 18 point this colour is 70 70 0
 Use animation and the effects of BLINDS for TEXT and DISSOLVE
for IMAGES– they are quick and effective and bring in by paragraph
and then dim after mouse click to a mid grey colour 150 150 150
 Give your presentation a header … there is space in the top and it
also uses the colour 150, 150, 150 this uses Word Art and can be
stretched. Use VIEW / MASTER/ SLIDE MASTER to access
 If you need to hyperlink such as this is the URL for NISL if you use
this as a template the colour is already set and is 96 132 113. For a
visited Hyperlink use this colour which is 204 102 0
 Keep within the frame … this ensures it will not get clipped when
projecting.
 Use Bullet Points as indicated (Square colour is 128 128 0 )
Title: My Template
Starting Point
 This shadow text
 This is Hyperlink
 This is a visited Hyperlink (not activated)
 Secondary Colour 100 100 0
 Tertiary Colour is 128 128 0
 Emphasis Colour is 204 153 0
 Use the Grey shaded Back drop with text
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Annotation: Text and Graphics
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Do each line’s annotation separately
Use Blinds and set it to fast (not very fast)
Use the Effects Option to dim to grey
For Graphics use dissolve annotation
Ensure that indenting is not hung to do this first
set the bullets to numbers and then back to
bullets. Use Box bullet and this green which is
128, 128, 0
Use Rounded Boxes
where possible – use
Dissolve annotation
Graphics should use dissolve annotation
Slide Header and Links
 Make sure that you use the Header to complete
headings for each slide and check that every
slides have a proper heading – not just “slide
1” and “slide 2” but a full heading.
 Links should automatically have the correct
colour e.g. Google (new link, not visited) – if
not working properly thecolour is turquoise
and is a reserved colour for links and is 96, 132,
113
 Google (visited link) 204, 102, 0.
Copy and Pasting
 To get the features to work require simply copy
and pasting of features
 Click on the text box and right click on the
mouse and a menu should appear and you
select the Copy
 The move to the slide you wish to past to and
right click on the mouse and a menu should
appear and you select the Paste
 CTRL C and CTRL V are keystrokes that do the
same functions
Copy and Pasting – More
 In Power Point you can copy the entire slide
and paste it complete with the correct
formatting
 When you copy – you also copy the formatting
and the annotation style
 To Insert text that has the same format you can
copy from your Word document and using Edit
and Paste Special and then use unformatted
text and this will insert text with no formatting
so it will take on the formatting set in the text
box.
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Use a foot-note approach.
Example ~The nautilus is
similar in general form to
other cephalopods, with a
prominent head and
tentacles1
When using superscripts
make sure than they are
chronologically ordered
e.g. 1,2 and 3.
http://en.wikipedia.org/wiki/Image:Nautilus_pompilius.jpg
Referencing
For one images,
if it is a short
URL use grey
(150, 150, 150)
using Arial
Narrow 12 font
and turn sideways – otherwise
put in notes.
Colour Palette
Regular Colours
Emphasis Colours – use sparingly
Pastel Colours – useful for transparencies