Cartography and GIS: Principles of Map Design, Coordinate Systems, and Projections

CHAPTER ONE
Introduction
Basics of cartography

Unit 1: Learning Objectives
At the end of this unit, the students will be able to:
Define Cartography and differentiate from
Geography
Write the history of cartography,
Examine the current development of
cartography,
Illustrate how cartographic process is
accomplished,
2

Unit One: Introduction
Cartography is about maps
The design and production of maps by
individuals or organizations;
The scientific study of the technology of
mapmaking and the effectiveness of maps as
communication devices; and
The use of maps as research tools and as
sources of information, and the study of maps
as historical documents and works of art.
3

Cont‟d
The term‘s association with mapmaking reflects
lexical roots in carte (French for map) and
graphie (Greek for writing).
Map Reading is the way of understanding and
interpreting of maps with a meaningful spatial
and non-spatial data analysis produced by
cartographers

4

1.1 Definition of Cartography
Learning Objectives
At the end of this lesson, students will be able to:
Define Cartography in different ways,
List the factors for change of definition of
cartography,
Differentiate cartography and geography,
5

1.1 Definition of Cartography
Some of the most relevant definitions given by
different scholars and organizations are as
follows;
Science that studies geographical maps and
the methods and processes of their compilation
and reproduction." M. Shokalsky, V.A.
Kamenetsky, 1930
"The science of making any map, embracing all
phases of work from surveying to map printing"
Cartographic Office of the United Nations
Organization, 1949
6

Cont‟d
"Cartography ranged from the study of
information, collected by "surveyors" - using
that word in its widest observational sense - to
the final reproduction of maps and charts at
any scale, on any subject and by any means"
Cartography Subcommittee of the British
National Committee for Geography of the
Royal Society, 1965
"The conception, the designing and the
execution of the map." Robinson
7

Cont‟d
"Cartography is the totality of investigation and
operations - scientific, artistic and technical -
which have as their aim the making of maps
and as well as the use of maps"
Commission on Cartographic Education of the
International Cartographic Association
"Cartography is the art, science and technology
of making maps together with their study as
scientific documents and works of art"
British Cartographic Society
8

Cont‟d
"Cartography is the theory, technique and
practice of map making and map use" Kolacny.
The meaning of the term „cartography‟ has
been changed fundamentally since 1960.
Before 1960 cartography was generally defined
as „manufacturing maps‟.
After 1960,cartography was defined not only
the manufacturing of maps, but also their
use is regarded as belonging to the field of
cartography
9

Cont‟d
The change of the definition is due to two
factors:
1.The fact that the subject has moved in to the
field of communication science
2.The advent of the computers
Therefore, Cartography nowadays is seen as ‗the
conveying of spatial information by means of
maps.’
10

Cont‟d
As a conclusion, it is said that as cartographers
are to map makers, geographers are to map
readers.
In other way, it is said that ―Geographers know
where it is at‖ and ―Cartographers show where
it is at”
So, what do you understand about cartography
from the definitions given by different
scholars.?
11

Introduiction
One of the most useful approaches to the
study of cartography is to view maps as a
form of visual communication with special-
purpose language for describing spatial
relationships.
The four main stages in cartographic process
are: 1. data collection, organization, and
manipulation; 2. map design and artwork
preparation; 3. map production and 4. map
reproduction

12

Schematic diagrams of map making process
Data
collection,
organizing &
manipulation
1
Map design
and art work
preparation
2

Map
Production
3
Mapping
efficiency
Map
Reproduction
4

Map
Storage
(Analogue)
Map Storage
(Digital)
13

1. Data Collection, Organization and Manipulation
Data must be collected from:
– existing maps,
– aerial photographs or
–satellite imagery,
–documents, e.g. legal descriptions of
property boundaries, historical documents,
etc.,
–field work or
–survey questionnaires.
14

Cont‟d
The data must be organized and manipulated
into a form which is suitable for mapping
This may involve aggregating data to some
specified set of spatial units, calculating
percentages, densities or other summary
measures from the raw data.
15

2. Design and Preparation of Maps,
Charts, Plans and Graphs
Many decisions go into the design of an
effective map.
These include the selection of the geographic
features and thematic attributes to be
represented on the map, projection type, map
scale.
A small scale map can show a large area but
little detail while a large scale map shows a
smaller area but with more detail.
16

Cont‟d
Designing the map also includes consideration
of how the information will be symbolized.
Do you show the data in color or not?
Can you afford to reproduce the map in colour?
Are the data qualitative or quantitative?
Will you represent the data using point, line or
area symbols?
How will you arrange the map itself as well as
items such as title blocks, legends, and scale
symbols on the page?

17

3. Map Production
In the process of map development after
designing the actual map, cartographers should
produce a single map for check up.
Before map is reproduced in the required
quantity, the quality of the map, whether the
conventional signs and symbols are used or
not, producing a single map is important.
This is mainly important for correcting the
human errors done in the design step
18

Cont‟d
If maps are reproduced in a required quantity
with out checking the errors at this stage,
unnecessary costs and time might be
incurred.
Eg. If scale is missed to put in the marginal
information, if blue color is used for
vegetation type.

19

4. Map Reproduction
How many copies of the map will be required?
In some instances, distribution of maps in digital
format on tape, disk or CD-ROM is replacing or
at least reducing the need for printed maps.
Finally, if cartography is a form of communication,
the measure of a good map is how well it
conveys information to its readers to enlighten,
convince, or persuade.
Therefore, to ask "what is a good map?" is to ask
how well it communicates with its audience
20

Cartographic communication process
21

UNIT 2: Coordinate System
Unit Learning Objectives
At the end of this unit, students will be able to:
–Define coordinate system;
–List the types of coordinate system;
–Find the position of an object in coordinate
system;
–Differentiate Cartesian coordinate system
from geographic coordinate system,
–Differentiate vertical and horizontal datum;
–Identify the grid reference of locations.
22

Cont‟d
Each set of numbers corresponds to exactly one
position in space, this system of assigned
numbers is called a coordinate system.
For identifying each position in space uniquely,
three numbers are required; as space is three-
dimensional (these numbers correspond to
length, width, and height)
23

Lesson 2.1: Types of Coordinate System
The location represented by the star has the
coordinates 7 (X-axis), 4 (Y-axis).
24

Types of coordinate System
The two types of coordinate system are:
Geographical Coordinate System
Cartesian Coordinate system
1. Geographical Coordinate System
One of the oldest systematic methods of location is
based upon the geographic coordinate system
Any point on the earth's surface can be located by
drawing a network of reference lines that run:
a) east-west around the globe (parallel to the equator),
and

25

Geographic coordinate system
b) north-south crossing the equator at right angles
and converging at the poles
The distance of a point north or south of the
equator is known as its latitude
The rings around the earth parallel to the equator
are called parallels of latitude or simply parallels
Lines of latitude run east-west but north-south
distances are measured between them
26

Geographic coordinate system
A second set of rings around the globe at right
angles to lines of latitude and passing through the
poles is known as meridians of longitude or
simply meridians
One meridian is designated as the prime meridian
The prime meridian of the system we use runs
through Greenwich, England and is known as the
Greenwich meridian
The distance east or west of a prime meridian to a
point is known as its longitude

27

Geographic coordinate system
Lines of longitude (meridians) run north-south
but east-west distances are measured between
them

28

Prima Meridian and Equator
29

Cont‟d
Geographic coordinates are expressed in
angular measurement
Each circle is divided into 360 degrees, each
degree into 60 minutes, and each minute into 60
seconds
The degree is symbolized by ° , the minute by ′,
and the second by ″
Starting with 0° at the equator, the parallels of
latitude are numbered to 90° both north and
south
30

Angular Measurements
31

Geographic coordinate
The extremities are the north pole at 90° north
latitude and the south pole at 90° south latitude
Starting with 0° at the prime meridian, longitude
is measured both east and west around the
world
Lines east of the prime meridian are numbered
to 180° and identified as east longitude
Lines west of the prime meridian are numbered
to 180° and identified as west longitude
32

Latitude and longitude
33

Geographic coordinate
The line directly opposite the prime meridian,
180°, may be referred to as either east or west
longitude
At any point on the earth, the ground distance
covered by one degree of latitude is about 111
kilometers (69 miles); one second is equal to
about 30 meters (100 feet)
The ground distance covered by one degree of
longitude at the equator is also about 111
kilometers,
34

Geographic coordinate
But it decreases as one moves north or south,
until it becomes zero at the poles

35

Length‟s at different Latitude and Longitude =111Km
X Sin(90
0
-latitude)

Length of One Degree of Longitude
(on WGS 84 Ellipsoid)
Length of a Degree of Latitude
(on the WGS 84 Ellipsoid)
Latitude Kilometres Miles Latitude Kilometres Miles
0º 111.32 69.17 0º 110.57 68.71
10º 109.64 68.13 10º 110.61 68.73
20º 104.65 65.03 20º 110.70 68.79
30º 96.49 59.95 30º 110.85 68.88
40º 85.39 53.06 40º 111.04 68.99
50º 71.70 44.55 50º 111.23 69.12
60º 55.80 34.67 60º 111.41 69.23
70º 38.19 23.73 70º 111.56 69.32
80º 19.39 12.05 80º 111.66 69.38
90º 0.00 0.00 90º 111.69 69.40
36

Geographic coordinate
Geographic coordinates composed by :
1. latitudes: angular distance measurement measure from equator (0
degree) towards north and south up to 90 degree
2. longitude : angular distance measurement measure from prime
meridian (0 degree) towards east and west up to 180 degree
3.Parallels : are an imaginary line joining points having the same
latitude.
4.Meridians: are an imaginary line joining points having the same
longitude.
37

Cont‟d
Because the earth is not perfectly round, a
spheroid can help maintain accuracy for a map,
depending on the location on the earth. A
spheroid is an ellipsoid that is based on an
ellipse, whereas a sphere is based on a circle.
38

Cont‟d
The shape of the ellipse is determined by two radii.
The longer radius is called the semi-major axis,
and the shorter radius is called the semi-minor axis
39

Cont‟d
The shape of the ellipsoid is defined by its semi-
major axis (a), or semi-minor axis (b) and
flattening (f) or eccentricity (e)
F= (a-b)/a Where, a= 6,371,837 m,
b= 6,356,752.3142m
E
2
= (a
2
-b
2
)/a
2


F=0.0023674

E
40

Cartesian Coordinate System
The Cartesian Coordinate System, also known
as the rectangular coordinate system, consists
of two number scales, called the x-axis (at y = 0)
and the y-axis (at x = 0), that are perpendicular
to each other.
Cartesian coordinate system can be divided in to
two types namely, Two-dimensional Coordinate
System and Three-dimensional Cartesian
System
41

Examples of simple Cartesian coordinate system with
quadrant
42

2.2 Datum, Ellipsoid and Geoid
Datum: A datum is a model of the earth that is used in mapping.
Geodetic datum defines the reference systems that describe the size
and shape of the earth.
Hundreds of different datum have been used to frame position
descriptions since the first estimates of the earth's size made by
Aristotle.
A datum is a set of values that defines the position of the spheroid
relative to the center of the earth
The datum provides a frame of reference for measuring locations and
defines the origin and orientation of latitude and longitude lines.
43

Cont‟d
Some datums are global and intend to provide good average
accuracy around the world.
 A local datum aligns its spheroid to closely fit the earth's surface in
a particular area.
For example Ethiopia uses the local Datum Adindan, United States
uses the North American Datum, in Japan the Tokyo Datum, in
some European countries the European Datum, in Germany the
Potsdam Datum and the global datum World Geodetic System 84
(WGS 84)

44

Cont‟d
Ellipsoid
An ellipsoid is formed when an ellipse is rotated about its minor
axis.
Note that ellipsoid and spheroid are being treated as equivalent
and interchangeable words.
45

Cont‟d
Ellipsoid as a reference surface can be local or
global.
The local reference ellipsoids is important
only to fit to earth‘s shape over a particular
country or continent.
Ethiopia uses the local ellipsoids called Clarke
1880.
The World Geodetic System 1984 (WGS84)
provide the basic reference frame for GPS
(Global Positioning System) measurements.
46

Geoid
The earth's surface is not uniform. Only a part of
it, the oceans, can be treated as reasonably
uniform.
The surface or topography of the land masses
show large vertical variations between mountains
and valleys which make it impossible to
approximate the shape of the earth with any
reasonably simple mathematical model.
The zero surfaces to which elevations or heights
are referred is called a vertical datum.
47

Geoids
Perspective view of the Geoid or Geoid undulations. 48

Cont‟d
The mean sea level (MSL) then is defined as the zero elevation
for a local or regional area.
Geoid is the true zero surface for measuring elevations.
For practical purposes, we assume that at the coastline the
geoid and the MSL surfaces are essentially the same.
Nevertheless, as we move inland we measure heights relative to
the zero height at the coast, which in effect means relative to
mean sea level (MSL).
49

Reference Surfaces
The physical surface of the Earth is complex in shape and in
order to represent it on plane, it is necessary to move from
the physical surfaces to a mathematical one.
In mapping three different surfaces are used:
1.Topographic reference surface
2.The ellipsoid or spheroid, for measuring locations
3.Geoid reference or Vertical datum: for measuring heights
50

Cont‟d
51

The Grid System
The grid system on a map allows us to identify locations
Helps us communicate them to other people with an internationally
accepted system.
When you identify a location using the grid system it is called using a
“grid reference.”
space partitioned into square cells and measured by meters.
 Each grid line is one of an even-interval selection of measurement
units.
The north-south lines numbered from west to east are called eastings

52

Grids
and the east-west lines numbered from the equator to the north are called northings.
grids are expressed in the native X and Y coordinates of the coordinate system of the
component.
Grid coordinate –
a set of letters and numbers specifying the location of a point to the desired position within a
100,000 meter square

53

Principles of Grid Reference
54

Types of Grid Reference

The commonly used grid references are:

1.The four digit grid references
2.The six digit grid references
55

The four digit Grid Reference
The four-figure grid reference refers to the entire grid square
When any reference point is given on the map, always take the easting number
first and then the northing second.

The square containing
point A, the normal
reference is 8254. This is
the four figure grid
reference.
56

57
The four digit Grid Reference

58
The Six digit Grid Reference

The Six digit Grid Reference

59

Steps in assigning six digit grid reference
1. Always refer to the south-west corner of the square in which the point lies (if it lies
on a printed line, follow this line until the south-west corner is reached).
2. Write down the tens and units of the Eastings printed on the line running vertically
through the corner.
3. Estimate the tenths eastward by dividing the square vertically in to ten parts, and
add the figure to the previous one.
4. Write down tens and units of the northing printed on the line running horizontally
through the corner.
5. Estimate the tenths north ward by dividing the square horizontally in to ten parts,
and add the figure to the previous one.
6. Combine these two groups of figures. Always write the easting before the
northing.

60

Example
61

The Basics of the UTM Grid
The UTM grid has been designed to cover that
part of the world between latitude 84°N and
latitude 80°S,
As its name implies, is imposed on the transverse
Mercator projection
Each of the 60 zones (6 degrees wide) has its
own origin at the intersection of its central
meridian and the equator
Base values (in meters) are assigned to the
central meridian and the equator
62

63
The Basics of the UTM Grid

The grid lines are drawn at regular intervals parallel to
these two base lines
Distances are always measured RIGHT and UP (east
and north as the reader faces the map)
And the assigned values are called "false easting" and
"false northing
The false Easting value for each central meridian is
500,000 meters,
And the false northing value for the equator is 0 meters
when measuring in the northern hemisphere and
10,000,000 meters when measuring in the SH 64
The Basics of the UTM Grid

The Basics of the UTM Grid
For the transverse Mercator projection, the
earth's surface between 80°S and 84°N is
divided into 60 zones, each 6° wide.
These zones are numbered from west to east, 1
through 60 N- S zones, starting at the 180°
meridian.
It is divided into 20 west-east rows in which 19
are 8° high and 1 row at the extreme north is 12°
high
65

These rows are then lettered, from south to
north, C through X (I and O were omitted).
Any 6° by 8° zone or 6° by 12° zone is identified
by giving the number and letter of the grid zone
and row in which it lies
These are read RIGHT and UP (east and north
as the reader faces the map)so the number is
always written before the letter
66
The Basics of the UTM Grid

This combination of zone number and row letter
constitutes the grid zone designation.
The earth's surface is divided into 6° by 8° quadrangles,
and covered these with 100,000-meter squares
Grid Lines are regularly spaced lines that make the UTM grid
on any large-scale maps
They are divisions of the 100,000-meter square
The lines are spaced at 10,000 or 1,000 meter intervals
depending on the scale of the map

67
UTM Grid Zone Location

Universal Transverse Mercator Zones
One of the rectangular systems used to determine
the position of an object on the surface of the
Earth is the Universal Transverse Mercator (UTM)
system
It has been designed to cover that part of the word
between latitude 84° N and latitude 80° S
 It is used, with the cylinder in 60 positions.
It creates 60 zones around the world. Positions
are measured using Eastings and Northings,
measured in meters, instead of Latitude and
Longitude.
68

Universal Transverse Mercator Zones
69

UNIT 3: MAP PROJECTION
Unit Objectives
At the end of this unit, students will be able to:
Define map projection
Classify projection depending on different bases;
List the steps in the creation of map projection
Explain the properties of map projection;
Illustrate the uses of different projection;
Select the suitable projection based on different
requirements.
70

3.1 Map projection concept & Definition
What is Map?
oRepresentation of either the whole earth or a portion of it on a two
dimensional surface/plane surface/.
oIt has network of parallels of latitude and meridians of longitude
oThe parallels and the meridians serve as coordinates for locating the absolute
location of points on the ground.
oThey are known as coordinate systems
71

What is map projection?
It is a systematic representation of the parallels of latitude and the
meridians of longitude of the spherical surface of the earth on a plane
surface.
The network of the parallels and the meridians so formed is a graticule
Our earth resembles a sphere.
This is truly represented on a globe
There are a number of methods of transferring the parallels and the
meridians of a globe on a plane surface

72

The shape of the meridians drawn by one method is quite
different from the other.
It is not possible to reproduce on a plane surface an exact copy of
the parallels of latitude and the meridians of longitude
Because of this it is not possible to maintain area, shape, direction
on a map by a single type of projection
A map projection showing area will not maintain shape and
direction
There is always distortion.

73

Why is it necessary to construct a map projection?
Our earth is round and it resembles a sphere
It is truly represented by a globe.
Size, shape and direction of an area can be correctly represented
on a globe,
But the globe is not always convenient because of the following
reasons:

74

We cannot see all the countries on a globe at a glance /at one time/
It is difficult to measure distances on a globe due to the spherical nature of its
surface.
It is difficult to carry a globe from place to place.
It is not possible to trace maps accurately because a tracing paper when coming in
contact with a globe develops many creases /folds/
A map can be traced on a flat surface without any difficulty.
75

Classification of map projection
Map projection can be classified in to different classes based
on:
1.Developable surfaces
2.Preserved qualities
3.Mode of development
76

Classification of Map Projection
1. Based on developable surface used
A) Conical projection- On a conical surface
B) Cylindrical projection- On a cylindrical surface
C) Zenithal or Azimuthal or planar projection- On plane
surface

77

Projection based on developable surface
78

Cont‟d
2. Based on preserved qualities
Homolographic or equal area projection
Orthomorphic/conformal or true shape projection
Azimuthal or true bearing projections
Equidistant or equal distance

79

3.Based on mode of development
(mathematical/geometrical)
Perspective/ use of light
Gnomonic projections place the light source at the
center of the globe.
Stereographic projections place the light source at
the antipode of the point of tangency.
Orthographic projections place the light source an
infinite distance from the point of tangency, resulting
in parallel light rays.

80

Projection based on the source of light
81

Non perspective/ mathematical ways
Equal area
Orthomorphic
General purpose
Conventional
Sinusoidal
Mollweide‘s
82

Dimensions of the earth
1.The equatorial diameter of the earth=12756.4km
2.The polar diameter=12713.2 km
3.Equatorial radius =6378.2 km
4.Equatorial circumference = 40, 075.4 km
5.Meridional circumference =40,0008.4 km
6.Polar radius =6356.6 km
7.Elipticity (flattening index)= 1/298
8.Surface area =510077492.3 km
9..Radius of the sphere =6370.89 km
10. Length of 1degree of longitude near the equator=111.32 km
11.Length of 1degree of latitude at equator =110.56 km

83

Map projection based on developable surface
and their properties

Cylindrical
Conical
Planar
84

Cylindrical map projection
The parallels and the meridians are transferred to a cylinder
The main principle is the globe is circumscribed in the cylinder and the
cylinder touches the globe at the equator.
The tangential point is true to scale.
The parallels are straight lines.
Each parallel is equal in length to the equator.
The parallels are longer than the corresponding parallel in the globe
85

Cylindrical map projection
The length of the equator on the cylinder is equal to the length of
the equator on the globe
The meridians are straight lines
They intersect the equator at right angels and they are equi-spaced
in all latitudes
This projection is quit suitable for showing equatorial regions.
86

Projection from a globe on to a
cylindrical projection surface
87

Types of cylindrical projections

I.The simple cylindrical projection
II.The cylindrical equal area projection
III.The Mercator’s projection
88

Uses
The projection is commonly used for navigational purposes
both on the sea and in the air
Wind direction, ocean currents and pressure systems are
shown on this projection
Maps of tropical countries are shown on this projection
89

Conical projection
The graticules of a globe are transferred to a
cone .
There is one parallel along which the cone
touches the globe
This parallel is called the standard parallel
The maximum coverage is up to the equator
90

Conical projection

91

Common properties
All parallels are concentric circles and all are arcs of a circle.
Meridians are straight lines but sometimes they are curved
The central meridian or the line of axis is always a straight line
The distance between meridians decreases towards the pole.
The convergence point is along the axis.
The projection represent only one hemisphere at a time
This is the maximum coverage
The standard parallel is correct to scale
These projections are most suitable for representing middle latitudes.

92

Types of conical projections
Simple conical projection with one standard parallel
Simple conical projection with two standard parallel
Bonne‘s projection
Polyconic projection
International map projection
93

Zenithal/Planar projection
It is constructed by projecting the parallels and the meridians of the globe
The plane is placed tangentially to the globe at one of the poles.
94

Properties
The pole is the center of the projection
The parallels are concentric circles
The meridians on the globe are great circles
But they are projected as straight lines
The meridians are straight lines radiating from the
center of the projection
They are spaced uniformly at the correct angular
interval
95

Properties
The plane is placed tangentially at one of the poles
The center of the projection coincides with the pole
The projection represent true azimuth
The outline of the map is circular
The meridians intersect the parallels at right angle
The projection are more suitable for showing polar
areas than other areas
96

Types of zenithal projection
The polar zenithal equal area
The polar zenithal equidistant
The polar gnomonic
The polar stereographic
The polar orthogrpahic
97

The polar zenithal equal area

Properties
The parallels are concentric circles
The pole is a point forming the center of the
projection
The meridians are straight lines radiating from the
pole
The meridians intersect the parallels at right angels
The distance between parallels go on decreasing

98

Properties
Limitations:
Shapes distorted away from the center of the
projection
The central part of the projection is true to scale
uses
Area is preserved
Used for making general purpose maps.

99

The polar zenithal equal area

100

3.2 Properties of Map Projection
Some distortion of conformality, distance,
direction, and area always result from
projection process.
Some projections minimize distortions in some
of these properties at the expense of
maximizing errors in others.
Regardless of what type of projection is used, it
is inevitable that some error or distortion will
occur in transforming a spherical surface into a
flat surface.
101

Cont‟d
The four (4) valuable properties of map
projection:
Conformality –True shape
Equivalence –True area
Equidistance –True distance
True direction
However, no map projection can be true in all
properties
102

1. Conformal Property:
It is the characteristic of true shape or
orthomorphic, wherein a projection preserves
the shape of any small geographical area.
 This is accomplished by exact transformation
of angles around points.
The property of conformality is important in
maps which are used for analyzing, guiding, or
recording motion, as in navigation in the sea, air
and meteorological charts.
No map projection preserve shapes of large area.

103

2. Equivalence Property
It is the characteristic of equal area.
Equivalent projections are used extensively for
thematic maps that show distributions of
phenomena such as population, agricultural land,
forested areas, etc
Equal area projections preserve the area of
displayed features. To do this, the other
properties— shape, angle, distance —are
distorted.
104

3. Equidistance Property
It is the characteristic of true distance measuring.
If this property is used the scale of distance is
constant over the entire map.
This property can be fulfilled on any given map
from one, or at most two, points in any direction
or along certain lines.
Equidistance is important in maps which are
used for analyzing velocity, e.g. ocean currents.
105

4. True direction property.
It is characterized by true direction line between
two points which crosses reference lines, e.g.
meridians, at a constant angle or azimuth.
These are termed rhumb lines and this property
makes it comparatively easy to chart a navigational
course.
However, on a spherical surface, the shortest
surface distance between two points is a great
circle along which azimuths constantly change.
Note that all meridians are great circles, but the
only parallel that is a great circle is the equator.
106

3.3 Classes of Map Projection
Classes of map projection are categorized based
on the developable surface.
Although an infinite number of map projections
are theoretically possible, approximately 400
projections have been described in the literature
and only a few dozen of these are widely used.
 The three classes of map projections are
cylindrical, conical, and azimuthal.

107

UNIT 4: Cartographic Data
Representations & Generalization
Learning Unit Objectives
At the end of this unit, the students will be able to:
Map quantitative and qualitative data,
Define cartographic generalization
Realize the importance of cartographic
generalization
Recognize the elements and controls of
cartographic generalization.
Differentiate the two types of generalization.

108

Cartographic Data Representations &
Generalization
Once geographic features and data have been selected,
generalized and classified for the map, it is necessary to choose
the appropriate graphic representation or symbols for the
information.
Visual variables include symbol, size, shape, orientation, pattern
(texture), hue (colour), and colour value (brightness and
lightness).
When a data set is large, it is not practical to assign a unique
symbol to each data record. Therefore, for mapping it is essential
that data is classified or grouped.
109

Cont‟d
Before classifying or grouping data, it is necessary to
determine whether the data are qualitative or
quantitative, and the level of measurement.
The basic concept of cartographic generalization is
important in map making that any cartographer to know
and apply.
The classification method chosen should adequately
describe the phenomenon being mapped, and at the same
time facilitate the cartographic display of spatial
patterns.
110

4.1 Mapping Quantitative and
Qualitative Data
Cartographers use symbols on maps to represent various
geographic phenomena involving location, distance,
volume, movement, function, process, correlation, etc.
These phenomena can be classified into four basic
categories: point (non-dimensional data), line (one-
dimensional data), area (two-dimensional data), and
volume (three-dimensional data).
111

Cont‟d
The geographical data must be represented on
maps by only three basic symbol types: point,
line, and area.
Before assigning map symbology, it is important
to have a good understanding of the data set to
be mapped.
The distribution of a data set can be explored by
calculating descriptive statistics such as mean,
mode, median, range, and standard deviation.
112

Cont‟d
Quantitative data are data that contain attributes
indicating differences in amount and can be
expressed as numerical values.
Quantitative data included in this category are
ordinal, interval, and ratio.
Moreover, Qualitative data are data that are grouped
in classes according to differences in type or quality.
Qualitative data have no numerical values attached.
Nominal data comes under this category. Sometimes
ordinal data may also be considered qualitative, if no
numerical values are involved 113

1. Ordinal data
Ordinal data provide information about rank or
hierarchy, in other words, relative values.
In Ordinal data, therefore, it is possible to
describe one item as larger or smaller than
another, or as low, medium, or high.
However, it is not possible to measure the
differences between ordinal data, because there
are no specific numerical values attached to
them.
114

Examples of Ordinal Data as point, line & area map
115

2. Interval data and Ratio data
The information can be arranged along a scale using
a standard unit.
It is possible to calculate the distance or difference
between ranks, which must be expressed in terms of
a standard unit.
For example, a temperature scale uses degrees (°F or
°C) as a standard unit of measurement; between 20°
and 35° there is a difference of 15°.
As shown by this example of interval data, it cannot
be said that 35° is 1.75 times warmer than 20°,
because the scale on which temperature is measured
is arbitrary.
Interval data, as illustrated, have no natural zero.
116

Cont‟d
Ratio data are the same as interval data, except
there is a natural zero; therefore, it is possible to
express data as ratios.
Physical measurements of height, weight, and
length are examples of ratio variables.
With this type of data, it is meaningful to state
that a measurement is twice that of another.
In some literature and statistical computer
programs, no distinction is made between
interval and ratio data, calling them both
continuous data.

117

118
Examples of interval and Ratio Data as point, line
& area map

Cont‟d
There are many statistical methods for the
classification or ranging of interval/ratio data.
In cartography, the four most common are: equal
steps, quantiles, standard deviation, and natural
breaks.
The equal steps method divides the data set into
classes with equal intervals between them.
The data may be arranged from high to low, or
low to high values.
 In this method the difference between the high
and low values of the distribution is divided into
a number of equally spaced steps.
119

Cont‟d
In quantile classifications the data are arranged
in sequence from low to high values and the
number of individual observations are counted.
The observations are then divided into the
selected number of classes, each class
containing the same number of observations.
The term quartile is used when the data are
divided into four classes and this method is
useful for mapping rectangular distributions.
120

Cont‟d
In the standard deviation method the mean or central point
of the data distribution must first be calculated.
The standard deviation is then used to set the classes.
This method is useful if the data distribution is a normal
curve.
The natural breaks method of classification is based on the
subjective recognition of gaps in the distribution, where
there are significantly fewer observations.
121

3. Nominal Data
Nominal data are discrete and are classed
according to type or quality.
For example, a line could represent either a road
or river, and a land use polygon could be
residential, commercial, or a recreational area.
Nominal data are often labeled with numbers or
letters, but these labels do not imply ranking.
Nominal data can be shown as point, line and
area symbology.
122

Examples of Nominal Data as point, line & area map
123

4.2 Elements and Controls of
Cartographic Generalization
Cartographic generalization may be defined as a
set of proceedings applied for construction and
visualization of models.
Cartographic generalization depend on the
cartographer‘s knowledge about the
requirements and the desired scale.
Generalization entails information loss, but one
should try to preserve the essence of the
contents of the original map.
124

4.2.1 Elements of Cartographic
Generalization
Generalization has a long history in cartography
as an art of creating maps for different scale and
purpose.
Cartographic generalization is the process of
selecting and representing information on a map
in a way that adapts to the scale of the display
medium of the map.
Every map has, to some extent, been
generalized to match the criteria of display.
Generalization is meant to be context specific
125

Types of Generalization
The two types of generalization are distinguished
as graphic and conceptual generalization.
Graphic generalization is characterized by
simplification, enlargement, displacement,
merging and selection.
Conceptual generalization is also characterized
by the processes of merging and selection, and
in addition comprises symbolization and
enhancement.
126

Cont‟d
The difference between graphic & conceptualize
generalization is that the process linked to
graphic generalization mostly deal with
geometric component of geospatial data, while
those processes mainly linked to conceptual
generalization mainly affect the attribute
component.
None of these processes affects the symbology.
Dots stay dots, dashes remain dashes, and
patches stay patches.
127

Graphic generalization
128

Conceptual Generalization
129

a) Selection
Map generalization can take many forms, and is
designed to reduce the complexities of the real
world by strategically reducing additional and
unnecessary details. One way that geospatial data
can be reduced is through the selection process.
The cartographer can select and retain certain
elements that he/she deems the most necessary or
appropriate. In this method, the most important
elements stand out while lesser elements are left
out entirely.
For example, a directional map between two points
may have lesser and un-traveled roadways omitted
as not to confuse the map-reader 130

(b) Simplification
Simplification is a technique where shapes of
retained features are altered to enhance visibility
and reduce complexity.
Smaller scale maps have more simplified
features than larger scale maps because they
simply exhibit more area.
An example of simplification is to scale and
remove points along an area.
131

(c) Combination or merging
A mountain chain may be isolated into several
smaller ridges and peaks with intermittent forest
in the natural environment, but shown as a
contiguous chain on the map, as determined by
scale.
(d) Smoothing
Smoothing is also a process that the
mapmaker can employ to reduce the
angularity of line work.
132

Cont‟d
Smoothing is yet another way of simplifying the
map features, but involves several other
characteristics of generalization that lead into
feature displacement and locational shifting.
Simplification, sometimes called smoothing,
should reduce the complexity of the map.
An example of smoothing would be for a jagged
roadway, cut through a mountain, to be
smoothed out so that the angular turns and
transitions appear much more fluid and natural.
133

(e) Enhancement
Enhancement is also a method that can be
employed by the cartographer to illuminate
specific elements that aid in map reading.
As many of the aforementioned generalizing
methods focus on the reduction and omission of
detail, the enhancement method concentrates on
the addition of detail.
Example is showing by contour lines for
elevation of relief features.
134

(f) Symbolization
Symbolization denotes that the relationship
between the symbol & the space it represents
changes.
After cartographers apply classification,
simplification, and exaggeration to features
selected for mapping, they are ready to translate
these features to graphic marks on the mark. We
call this process symbolization.
135

4.2.2 Controls of cartographic
Generalization
Cartographers don‘t have complete control over
the processes of generalization.
Generalization is also guided by a number of
external forces.
The following factors affect the generalization
process: map purpose & conditions of use,
quality and quantity of available data, map scale,
and graphic limits.
136

(a) Map Purpose and conditions of use
Before beginning to produce a map, a
cartographer must think of the purpose of the
map and the condition of use.
For example, is it designed to provide a great
deal of general geographic information or to
show the structure of a particular distribution?
(b) Map Scale:
The scale of the finished map also has a major
impact on the amount of generalization that will
be used.
137

Cont‟d
The smaller the scale, the more the
generalization will be will usually be required.
At large scales, most of the generalizations is the
classification and symbolization.
(c) Quality and quantity of data:
The quality and quantity of data available to
cartographers also greatly affect the
generalization process.
The more reliable and precise the data, the more
detail is available for presentation.
138

Cont‟d
One of the most difficult tasks for cartographers is to
indicate to map readers the quality of the data used.
On large scale maps, cartographers often include a
reliable diagram, which shows the relative accuracy of
various parts of the map.
The quantity of data available has a great impact on
the generalization process.
If not enough information is available, cartographers
should either make the map at a smaller, more generalized
scale or not make it at all.
139

(d) Graphic limits
We can break these factors in to two groups: (1)
technical limits set by the cartographer‟s tools
and (2) perceptual limits of the human eye.
We create symbols by combining the basic
graphic elements: point, line and area marks.
Our ability to form symbol from these elements
is subject to three types of limitation: physical,
physiological and psychological.
Physical limits are imposed on the graphic
elements by the equipment, materials and skills
available to the map maker.
140

Cont‟d
Physiological and Psychological limits are imposed
by the map user‟s perceptions and reactions to the
primary visual variables.
The visual variables are shape, size, orientation, hue,
value, chroma, arrangement and texture.
GIS and Automated Generalization
As GIS came up in the last century and the demand
for producing maps automatically increased
automated generalization became an important issue
for National Mapping Agencies (NMAs) and other
data providers. 141

Chapter 5

Maps
142

UNIT 5: MAPS (Introduction)
Learning Objectives
At the end of this unit, the students will be able to:
Define map,
Classify the types of maps,
Examine the uses of maps,
Elaborate the limitation of maps,

143

Introduction
It is a representation of all or part of the
earth‘s surface on a plane surface with
conventional signs.
The representation is drawn to a specific
scale.
a map is far smaller in size than the actual
area of the earth‘s surface it represents.
A cartographic representation with out a
scale should not be called a map, better call
it a diagram or sketch.

144

Characteristics of map
Represented on a Flat surface or plane surface
Reduction (a reduction ratio in proportion to reality, i.e., 1:10);
Generalization (are reduced in content, build up on a selection
of detail, condensed, etc)
Enhancement (example, by addition of contour lines which are
not visible in nature). 145

5.1 Classification of Maps
Maps are classified based three essential
things.
Based on Scale
Based on Purpose
Based on information they conveyed
146

Based on scale:
Large scale:
Greater than 1:50, 000
Medium scale:
1:50,000-1:250,000
Small scale :
Less than 1: 250,000

147

Based on scale:
Large scale:
Greater than 1:50, 000
1)Cadastral Map
Cadastral maps are used for demarcating the
boundaries of land properties, fields, gardens
and buildings. (Rural or Urban Cadastre)
Cadastral map is especially prepared and compiled
by the government agencies and is used for
revenue and tax purposes.
148

Cont‟d
2. Topographical Maps
It is prepared on large scale to show the general
surface features in detail, for example, natural
landscape as well as cultural landscape

It doesn‘t show the boundaries of individual lands.

It is very important tool for geographers and
military experts, because it depicts the
topographical forms like relief, drainage, swamp,
forests etc.

149

Cont‟d
Small scale maps
Less than 1:250,000
1. Wall Maps
maps are prepared for keen observation;
It is generally drawn boldly;
Its scale is larger than atlas maps but smaller
than topographical maps.
150

2. Atlas map
Atlas maps are also called chorographical
map
It is drawn on a very small scale e.g,
1:2,000,000
It provides highly generalized information of
physical, climatic and economic conditions of
different regions of the Earth.
151

Based on purpose
2) According to purpose maps are broadly
classified as follows:
(1) Physical maps
(2) Cultural maps
1) Physical Maps
Physical maps are those maps, which are
specially prepared for the natural product or God
gifted things such as heavenly body, soil,
vegetation, relief etc.
152

Types of Physical maps
(a)Geological Maps
This type of map is prepared to show the
type of rock, its occurrence and
depositions.
They are quite like topo-sheets which tell of
the geological structure of the region with the
aid colour-shades super imposed upon their
respective location.
153

Cont‟d
(b) Astronomical maps:
Astronomical maps are prepared to show the
heavenly bodies and It may be shown on large or
small scale.
(c) Relief maps
They portray the relief features of the land by hatchers, or
columnar or by different shades or tints (green, yellow, and
brown) between the contour lines;
It also show the drainage patterns there on.
Relief map is also known as chorographic map.
 It indicates the slopes, river systems, mountains, plateaus,
plains etc.
154

Cont‟d
(d) Climate maps:
 It is prepared to show the average weather
condition of a long period for example 30 years.
(e) Weather map:
It is produced by meteorological offices.
weather map is prepared to show the average
condition of temperature, pressure, wind and
precipitation over a short period of time.
155

Cont‟d
(f) Soil map:
It depicts the different soils of the area by
different shades or colors.
(g) Vegetation map:
 It is prepared to show the types and the
distribution of the various species of vegetations.
(h) Aeronautical charts:
help to pilots as they represents the
topographical features of the land in multi color-
contour lines are shown in brown; 156

Cont‟d
(i) Navigational Charts
Their main emphasis is on coasts and coastal
water;
They also show the depth of the sea, its bottom
relief and its tides and currents.
They show the cliffs along the shores with their
heights
157

Cultural maps
Cultural maps are maps which reflect man made
features which come in to existence due to the
interaction of activities of human beings with
nature.
Types of Cultural Maps
(a) Political maps:
This type of map represents the boundaries
between different political units. It may be village,
districts, regions, countries or continents.
As an example, the political map of Ethiopia shows
the distribution of regional state boundaries.
158

Cont‟d
(b) Land use map:
Using the human intervention, land is used
for different purpose.
The nature and character of land-use are
represented by this type of map.
(c) Historical map:
This type of map is prepared to show the
past events.
159

Cont‟d
(C) Military map: It is prepared to show the strategic
points, routs etc. for the convenience of military.
(d) Tourist map: A map that helps for tourists as a guide
where tourism sites located.
(e) Road map: Which represents different standards of
road on the map (Asphalt, all weather road, dry
weather road)
(f) Social maps: This type of map depicts, social
organism (tribes and races), their languages,
religions etc.
160

Maps based on the information they conveyed
(1)Thematic Maps
(2)General Maps
(1) Thematic Maps
It shows a specific information that shows a
single entity
Maps within this category usually have as
their background a simplified depiction of the
topography.
161

Cont‟d
It is also called topical map or specific map
maps as it show information about one specific
topic
For example, soil map, land use map,
population distribution map etc.
(2) General Maps
This type of map incorporate a variety of
information.
It is also called topographic maps
162

5.2 The Uses of Maps
During the ancient period, or the primitive societies, simple
maps are drawn in sand soil to show the location of a water
hole, river, an excellent hunting ground and the way how to get
there.
In this discussion we examine Map Uses from the perspective
of the generic task, such as analysis, communication,
exploration, etc
163

Modern use of maps
1. For Communication and Propaganda
Many maps are produced to convey general
information about an area or thematic information
about any number of subjects.
It is said as “ A single map worth's thousands of
words”
2. Navigation and Control
Whether we move on land, at sea, or in the air, we
rely heavily on maps to plan our routes and to
maintain our course.
164

Cont‟d
3. Planning
 The obvious forms of planning that use maps
are urban planning and regional planning.
Military operations rely heavily on maps whether
for the movement of vehicles and troops, the
assessment of enemy positions, or any number
of other possibilities.
Maps are also helpful to identify the potential of
areas subject to hazards ( natural and man-
made)
165

Cont‟d
4. Storage of Information
Maps give standardize information deemed to
be important, such are boundaries,
hydrography, topography, road network and
place names etc.
Fifty years old map may still be useful for the
examination of changes in topography and
hydrography and other information in
comparison to the current.
166

Cont‟d
In a general way maps are used for the following:
1. Identifying Position (location)
A map gives the location or position of places or
features.
The positions are usually given by the co-
ordinates of the place, either as the Cartesian
co-ordinates (x,y) in metres or as geographical
co-ordinates (latitude and longitude) in degrees,
minutes and seconds.
167

Cont‟d
2. Providing spatial relationships
A map gives us the spatial relationship between features
Example, What province is the neighbor of another province?
Where is the nearest railway station?
3. Determining distance, Direction, Area
We can measure the distance from Addis to chiroo, determine the
direction, or calculate the size of a region. But, there must be a
scaled map
168

5.3 Maps and their limitations
A photograph shows all objects in its view, but a
map is an abstraction of reality.
The cartographer selects only the information
that is essential to fulfill the purpose of the map.
Maps use symbols such as points, lines, area
patterns and colors to convey information.
Any practical map shrinks Earth features down to
a manageable size by scale.

169

Cont‟d
Only a true globe would allow a similar
conclusion for any pair of points on its surface.
In flat maps, most likely the scale will not be
constant, changing with direction and location.
Maps portray only the information that has been
chosen to fit the use of the map.
The information on maps is classified and
simplified, to make it easier to understand.
All maps use sign to stand for elements of reality.
170

Marginal and Border information
It explains map identifications and other marginal data appearing on
topographic maps prepared for use of different purposes.
The marginal information includes all information and graphics placed in
the margin; marginal information is added to identify the map (title, sheet
number, scale etc.), to specify the nature of conventions used.
Topographic maps have much more information added around the mapped
area and this is known as marginal and border information.
171

Cont‟d
The type and position of this information has been standardized as
follows
1.Margin: the area of paper surrounding the outer framework of
the map;
2. Neat line: the line (graticule or grid) enclosing the mapped
area;
3. Border: the area between the neat line and the outer
framework of the map;
4. Map face: mapped area enclosed by the neat line.
172

Outer Frame work
Neat line
173

List of Items in the margins
The items shown in the margins of a map can be
divided in to two groups:
(1) Compulsory items - This is information
regarded as essential and must be included
(2) Optional items- this is information regarded as
desirable and should be included if space
permits.
174

Instructions for the positioning of
compulsory items of Marginal information

(a) Sheet name- this is to be placed in the center of the
upper margin in large type and in the bottom right
corner of the lower margin in medium of or large
type.
(b) Series name- this is to be placed in the top right
corner and the bottom left corner of the margin in
medium type inside the panel described in paragraph
(e).
(c) Sheet number- the map sheet should be identified
beyond possibility of doubt by a system of
numbering, either national or international. The sheet
number is to be shown in the top right corner and
bottom left corner in medium type inside the panel
described in paragraph (e) 175

Cont‟d
(d) Edition Designation- Each edition of each map must
carry an edition number, which identifies that
particular version of sheet and placed in the top right
corner and bottom left corner in medium type.
( e) Sheet identification panel- to help to rapidly identify
a map sheet, both in use and in map store or library. It
is placed in the upper right and the lower left corner of
the sheet.
The panel is a box containing the following information:
(i) Series Number
(ii) Sheet Number
(iii) Edition Designation

176

Cont‟d
SERIES ETH4
SHEET 1239 A4
EDITION EMA1996

SERIES ETH4 SHEET 1239 A4 EDITION EMA 1996

Alternatively it may be shown in a single line
177

Cont‟d
(f) Numerical scale- This is to appear in medium
type in the lower margin, near the graphic scales,
and in medium or large type in the upper margin
next to the area of coverage.
(g) Graphic Scale- these will normally be in
kilometers and statute miles, with the addition of
meters and yards, it is to be placed in the center
of the lower margin.
(g) Units of elevation- To note elevation in meters
or elevation in feet
178

Cont‟d
(h) Contour Interval- this is to be show in medium
type in the lower margin near the graphic scales.
It should be in the form of : "Contour interval .......
Meters (or feet)―
(i) Conventional sign legend or reference- the
conventional signs used on the sheet.
(j) Index to adjoining sheet- A diagram to be
inserted in the lower left or right margin showing
the sheet in relation to the adjoining sheets
179

Index to adjoining sheet
1239 A1
TIRARE
1239 A2
BORA
1239 B1
MAICHEW
1239 A3
SEKOTA
1239 A4
BECHEKA
1239 B3
KOREM
1239 C1 1239 C2
1239 Dl
ALAMATA
180

Cont‟d
(k) Note concerning the grid (s)- Information is to
be given as to the grids to which lines, thick and
figures refer.
(l) Instruction on the use of the grid- every
girded map is to carry instructions on the use of
the grid reference system.
(m) Information on True North. Grid North and
Magnetic North: Each map sheet is to contain
the information necessary to determine the true,
grid and magnetic bearings of any line within the
sheet.
181

Cont‟d
True North (TN) - The direction of meridian to the
North Pole at any point in the map.
Magnetic North (MN)- The direction of the magnetic
North Pole as shown on a compass free from error or
disturbance.
Magnetic Declination- The angle between magnetic
north and true north at any point. Sometimes the
term magnetic variation is used and this is mainly on
Nautical and Aeronautical charts.
Grid convergence- The angle between grid north and
true north.
Annual Magnetic change- The amount by which the
magnetic Declination changes annually because of
the change in position of the magnetic north pole.
182

Cont‟d
183

Cont‟d
(n) Names and Boundaries disclaimer it can be
shown as ―Example: "This map is NOT an
authority on International boundaries."
(O) Projection. Spheroid. Geodetic Datum.
Leveling datum : note relating to the basis
geodetic data
(p) Publication note- This note is required to show
the publishing agency (in the case of our country
the responsible body is Ethiopian Mapping
Authority) responsible for the map
184

Cont‟d
(q) History note-
Examples of History note:
Edition 1 Prepared by Ethiopian Mapping
Authority in 1996,
Field survey Data by EMA
Air photograph by SWEDSURVEY November
1994,
Field compilation by EMA, March 1994
185

Cont‟d
(r) Copyright note- This is to protect the copy right
of a map a copyright note should be shown.
Example:
Copyright reserved to the Ethiopian Government,
1996.
 Copyright reserved to the State of the
Netherlands, 2002
186

Border Information
Border is the area between the neat line and
the outer framework. Thus, any relevant
information displayed in the border area is
known as border information.
(a) Geographical Co-ordinates of sheet corner-
The geographical coordinates of the sheet
corners are shown in degrees, minutes and
seconds to any appropriate accuracy.
(b) Values of graticules lines or ticks- these
should be shown at intervals around the neat
line.
187

Cont‟d
(d) Destination of roads or railways : The
destination is normally shown at an angle across
the border in continuation of the line of the road
or railway.
(e) Names of large features- The names of large
features or areas are shown, when practicable,
in the center of the feature (name placement).
188

Unit 6: MAP SCALE
Unit Learning Objectives
At the end of this unit, the students will be able to:
Define map scale;
Convert one form of scale in to another;
Classify the type of scale;
Enlarge and reduce map scale,
Recognize the concept of scale in cartography;
Mention the methods of representing scale.
189

6.1.Scale: Concept and Definitions
Map scale is refers to the proportionality between map distance with
ground distance and map area with ground area.
For example, if you have a map scale of 1:63,360, one unit of measure on the map
represents 63,360 units of the same measure in the real world.
The main purpose of the scale is to bring either the whole globe or a part of it on the
convenient size of paper.
The selection of scale depends on various factors.
1. The size of the paper;
2. The amount and characters of details of information to be
shown;
3. The size of the area to be mapped.

190

Cont‟d
Scale can be:
 metric
 non-metric scales.
Metric scale is represented in decameter, millimeter, centimeter, meter and
kilometer, where as
 Non-metric scale representation can be in miles, inches and feet system.
Different country uses different system, e.g. Ethiopia uses a metric system.
In a broad sense, scale can be divided into two measurable ways, namely:
1. Linear scale
2. Areal scale
191

Cont‟d
Basic formulas of scale

In reality, areal scale is not given on a map as
only linear scale is given as a standard because
areal scale can easily be found by squaring the
linear scale
192

6.2 Methods of Representing of Scale
The three ways of scale representations are:
(1)As an arithmetic ratio (the representative fraction),
(2) As a statement,
(3)As a graphic scale.
As a remark, in a well projected map, many maps include two or
even all three types of scales.
193

1. Representative Fraction (R.F) scale
This is a fraction in which the numerator always assigned the number 1,
denotes a unit of measure (inch, centimeter, feet) on the map, and the
denominator denotes the number of identical units (same as the map) of
actual distance on the map.
In other words, an R.F. is a ratio of MAP: LAND.
A mixture of units cannot be used without changing the numerical
relationship between map and land.
Representative Fraction may be shown as an actual fraction (e.g. 1/25,000)
or like a mathematical proportion with a colon (as in 1:25,000).

194

2. Verbal Scale
It is expressed in words, a relationship between
a map distance and a ground distance.
This scale is sometimes called statement scale
e.g. One inch to a mile
Six inches to a mile
Ten miles to an inch
N.B Don’t say one inch =(equal to) one mile
which obviously cannot be true.
195

3. Graphic Scale
It is a pictorial representation of the scale.
A graphic scale allows a distance measured on
the map to be translated directly into the correct
earth distance by comparing it to the scale.
Graphic scale is drawn with several primary
divisions towards the right of zero one division
with secondary divisions marked to the left of
the zero.
196

6.3 General Division of Scale
The smaller the denominator, the larger the scale.
A large scale map covers a small area, and vice versa.
As scale number becomes smaller, the simplification of the content and
graphic symbolization must be increased.
The larger the number represents the most generalized and condensed
appearance of the reality and the smaller the number becomes or
approaches to more accurate of the physical features.
197

Cont‟d
Large scale Medium scale Small and very small scale
1:2,000 >1:250,000
1:5,000 >1:50,000 1:1,000,000
1:10,000 1:100,000 1:2,500,000
Eg. For house Plans,
cadastral map, site
plan
1:200,000
1:250,000
1:25,000 -1:50,000 for large
scale topographic map
For medium scale
Topographic map
For small scale maps &
geographic maps
World map at very small scale
198

6.4 Conversion of scale
199
1. Statement of scale to R.F

It is to write the verbal scale as a fraction.
Remember that that 1 mile = 63,360 inches
and 1km=100000cms
Example 1: Find out the R.F., when the statement scale is 1cm to
5kms.
Given: 1cm to 5kms.
First change 5kms into centimeters to have the same units. To do
this multiply 5kms by 100,000cms (5  100,000 cms)
Now leave out the units and put your answer as a ratio, that is,
1:500,000 or 1/500,000 (R.F. scale)

2. R.F scale to Statement
 Most verbal scales are either "one inch represents X
miles," or "one centimeter represents X kilometers."
Example 1: The R.F. of a map is 1:500,000. Find out the
statement scale in terms of inches and miles.
In terms of inches, here, 1" represents 500,000 inches
In terms of miles, here 1" represents 500,000
63,360 miles
= 7.89 miles
Hence, the required statement scale is 1" to 7.89 miles
200

3. Statement of scale to Graphical scale
We can use the verbal scale like a fraction to
transform the ground distance to map distance.
Eample 1: Converting verbal scale of "1 cm to 14
km" to a graphic scale.

Example 2: Draw a graphical scale for 1" to 4 miles

201

4. RF to Graphic Scale
Here the denominator must be changed in to
ground distance measurement unit, like Kms,
miles
Example: convert an RF of 1:250,000 to a graphic
scale is:

202

5. Graphic Scale to RF
Here we must take a measurement using ruler
from the bar scale to determine the map distance
that corresponds to a ground distance.

1

0 1 2 3 4 5
KILOMETERS
203

6. Graphic Scale to verbal scale
we take measurements of one interval of the
primary division using ruler to represent the
map distance
For more convenient, it is better always to take
ruler measurement from ―0‖ to the next tick
mark. Example: 1cm represents 1kms

1

0 1 2 3 4 5
KILOMETERS
204

7. Linear scale into areal scale and vice versa
From the graphical scale, R.F and statement
scale, once the linear scale is known, the areal
scale can easily be determined simply by
squaring the linear scale.
Linear scale in the other way can be defined as
the square root of areal scale.
Convert the following linear scales into areal
scales.
Linear scale (1/ 100,000), thus, areal scale =
( 1/100,000)
2
= 1:10,000,000,000

205

6.5 Map scale enlargement and
reduction
Lesson Objectives
At the end of this lesson, students will be able to:
Enlarge maps based on the given proportion;
Reduce maps based on the given proportion;
Know the formula used to enlarge and reduce
a map;
List the methods of enlargement and reduction
of maps.
206

Methods of Enlargement & Reduction
The three methods used to enlarge or reduce
maps are:
1. Instrumental method
a) Panthograph, b) Eidograph
2. Cartographical method
a) The square method b) the similar triangle
method
3. Photographical method
This is by the help of camera producing negative 207

The square method
Measuring the size the square and enlarge it by the required
proportion

1: 100,000
(original map)
1: 50,000 (enlarged map)
208

Similar triangle method
Example: Enlarge 5:7 or reduce 5:2 ratio
209

Similar triangle method
This is used to enlarge or reduce a narrow strip of map.
E.g. stream, a road, or a railway.
Let RR be a stream.

210

Photographical method
It is enlarging or reduction by the help of Camera, using the
negative.
Enlargement= Old scale X n times

Reduction= Old scale X 1/n times
Example: Given that
Original scale = 1:100,000
Degree of enlargement = 2 times
The new scale = 2 X 1/100,000 = 1:50,000
211

Cont‟d
Example: Given that
Original scale = 1:25,000
Degree of reduction = 4 times
The new scale = 1 X 1 = 1____
4 25,000 100,000
212

Unit 7: Measurement and relief
representation on maps.
Learning Unit Objectives
At the end of this unit, the students will be able to:
Identify the marginal and border information on
topographic maps,
Develop cross sectional profile map,
Calculate the slope and gradient from the map.
Analyze different type of drainage system on the
map.
Measure distance and area from the map
Analyze and graphically represent thematic maps,
Convert geographical data in to graphs and diagrams

213

Lesson 7.1: Determining Distance and
Area from Map & Scale
The ground distance which can be calculated
by using the scale of a map and by measuring
a straight line distance is known as map
distance.
Map distance is the ―crow fly distance‘ which
does not consider the ups and downs of the
earth‘s curvature or it assumes the two
locations are at the same elevation--or that the
terrain is flat.
214

Distance
Distance can be
Straight line distance ( route distance)
Irregular distance (curve distance)
Field distance ( distance which considers slope difference/how much
the relief is inclined or displaced)
215

a) Measuring Distance
Straight line distance
Suppose we have a map with a scale of 1:50,000. We measure the
distance along a property boundary as 1.7 cm. What is the length in
the real world (boundary in the ground)?
Sol
n
To find ground distance, we must use the map
scale to convert map distance to ground
distance.
If 1cm=0.5Km (since we have to divide it by 100,000)
Then 1.7cm= X Kms
216

Cont‟d
X= 1.7 Cms X 0.5Kms X=0.88Kms
1cm
Example 2: On a map scale 1: 50,000 what is the ground distance
represented by six inches on the map?
Sol
n
If 1inch=0.79mile (since we have to divide it by 63360)
Then 6 inch= X mile
X= 6 inches X 0.79 miles X=4.74 miles
1inch

217

Scale = 1:200,000
B

A

218

Cont‟d
Irregular distance
These are distance along river channels, roads which
have boundaries with curvatures
To measure this we use thread which is not elastic or by
transferring it in to edge of paper by dividing the
curvatures.
Measure the distance measured by the thread by a ruler .
This will give us the map distance
Convert it into ground distance.
219

Scale = 1: 50,000

B

A
220

Example 2: Field distance measurement
by given Altitudes
Field distance is straight line distance that takes in to account
the altitude difference
Suppose the map distance from A to B is 8 cms and where A is
located at an altitude of 3500masl and B is at 1500masl.
Calculate the ground distance and field distance at a scale of 1:
50,000 and interpret the results.
Solution: Ground Distance = Scale x Map distance
100,000
FD
2
= AD
2
+ GD
2

Where, FD is Field Distance/slope/
AD is Altitude Difference
GD is ground Distance
221

222

Cont‟d
Based on this we have to find the altitude difference and
ground distance to compute field distance.
AD= 3500m - 1500m which is 2000m and if we divide it by
1000m, it will 2kms 223

Cont‟d
GD = 50,000 X 8cms which is 4 kms
100,000
Finally, we have to substitute to the field
distance formula
FD
2
= AD
2
+ GD
2
FD
2
= (2km)
2
+ (4km)
2

= 4km
2
+ 16 km
2

= 20 km
2 FD= 4.5Kms
224

Cont‟d
To conclude, the extra distance that shows the
relief displacement on the field distance along
AB is 0.5km, i.e. FD (4.5 kms) minus the GD
measurements (4kms).
d) Comparing Scales and Areas between
Different Maps
If we do have two maps, with the given R.F. scales simply divide the
larger scale number by the smaller one to get the scale factor.
225

Cont‟d
For instance, if the two maps A & B have R.F
scales of 1:50,000 and 1:10, 000 respectively,
the scale factor will be
SCALE FACTOR = R.F. of Map A = 1:50,000 = 5
R.F. of Map B 1:10,000

226

Measuring area
b) Measuring area of regular features from map and scale
Area must be expressed in areal units, which are usually
distance units squared -- cm
2
, mi
2
and so on.
We must therefore used squared conversion factors
when finding area from map measurements

227

Shape of the parcel(map) & formula to be used
=∏r
2

=L X W
= S
2

= 1 x BxH
2
228

Measuring area of irregular features
Most of the maps are irregular and there are different
techniques to measure areas of these features.
These are:
Grid square method
Polygon method
Strip method
Planimetre method
GIS techniques
229

Grid square method
Grids are vertical and horizontal lines which are meshed.
Steps:
Determine the scale
Determine the size of the squares
Draw grid squares
Count full squares and partial squares
Sum up all the values (add the partial squares and the full squares separately)
Calculate the ground area equivalent of one grid square
Multiply the total number of grids by ground value of one grid square
230

Strip method
Strips are parallel lines
Steps
Draw series of parallel lines with equal interval (d)
(d) is the distance between two parallel lines
Estimate the average length between two parallel lines
For estimation draw dot lines between two parallel lines
This will give the average distance between the parallel lines
Measure the length of the dot lines by using a ruler
Estimate the area by A = (L
1 x d) + (l
2 x d) + (l
3 x d) + l
n x d
A = d(L
1 + l
2 + l
3 --- + l
n )

231

c) Determining Scale from a Map or Photo

As a rule every map expected to have a scale.
However, map scale may be missing on:
–aerial photographs
–Specially designed maps for examination
purposes
Therefore, we can determine scale from a map or
photo which may be missing the scale by using
the two methods:
i) By measuring object of known size on map or
photo
ii) By using the latitudinal difference
232

Cont‟d
Example: A desktop globe has a diameter of 1.5 m.
Given that the Earth‘s diameter is 12,756 km,
calculate the scale of the globe as a
representative fraction.
Sol
n
Assume that, 1meter = 100cm, then
1.5m = X
X= 1.5m X 100cm
1m
X= 150cm, then 233

Cont‟d
If, 150 cm= 12,756km
1cm= X
X= 1cm X 12,756Km , X=85.04Km
150cm
Therefore we have to convert it in to
centimeters, to have the same units, and we
should multiply it by 100,000. Hence the scale
is 1: 8,504,400, or 1: 8,504,000 (To be
changed in the handout)
234

Example 2
Given the distance between points A and B on
the ground is 80 kilometers, calculate the
R.F. scale for the map given above. By using
ruler measurement, the map distance
between A and B is assumed to be 4cm
235

Cont‟d
If 4cms on the map = 80 kilometers on the ground,
then
1cm = X kilometers
X= 1cm X 80kms , X= 20kms
4cms
Finally, we have to multiply by 100,000 to change
in to the same units of centimeters and the scale
of the map becomes 1:2,000,000
236

Example 2: If latitude is given
Suppose that the map of Ethiopia extends from
3
0
00‟ – 15
0
00‟N latitudes. The map distance from
the south tip to the north tip part of the country
is measured 20cms. What will be the scale of the
map?
NB:
:
Known that: 1
0
of latitudinal difference on the
ground near the equator is roughly 110.5km or
approximately 111kms.
Since Ethiopia is located north of the equator,
first we have to deduct southern tip from the
northern tip (15
0
00‟ minus 3
0
00‟) which is equal
to 12
0
00‟.
237

Cont‟d
So, If, 1
0
= 111km
12
0
= X
X= 12
0
X 111Km , X= 1332Kms
1
0

Then, if 20cms= 1332 kms
1cm = X
X= 1cm X 1332Km , X= 66.6 Kms
20cms
Therefore, we have to convert it in to centimeters,
to have the same units, and we should multiply it
by 100,000. Hence the scale is 1: 6,660,000 238

6.2: Locating Places on a Map
In map reading, it is important to have a
systematic way of locating features, areas and
points on the map and this can be done using
the following:
a) Place names
b) Outstanding features
c) Direction and bearing
d) The grid system
e) Latitudes and longitudes 239

Cont‟d
Place names: These include on the
topographic and other maps like towns, villages,
regions, and weredas can be located using their
names.
Outstanding features: These include
mountains, hills, rivers, buildings and the like.
Latitude and Longitudes: These are lines
universally agreed upon and are used to create
cells on the surface of the earth for specifying
localities.
240

Cont‟d
Grid System: Using national grid some maps
are over printed with grid of kilometers squares
that from an excellent reference system to any
place on the map.
The numbers running west to east along the top
and bottom of the sheet is called Easting and
those running from north to south along the right
and left margins are called Northing.
241

Cont‟d
Direction and Bearing: Saying For example, “I
live 4 km from Dire Dawa town” does not give
the exact location of the place referred to.
Therefore, to be more specific one has to
mention the direction, as “I live 4 km north of
Dire Dawa town.”
Surveying and navigation uses the concept of
a whole circle bearing, consisting of 360°
subdivided into sixteen principal bearings
242

Cont‟d
The four main directions of a compass are
known as cardinal points. They are north (N),
east (E), south (S) and west (W).
Sometimes, the half-cardinal points of north-east
(NE), north-west (NW), south-east (SE) and
south-west (SW) are shown on the compass.
There are eight more points on the compass,
with names. They are called the secondary
intercardinal points.
243

Cont‟d
244

Main Points of the Compass Compass Bearing
North 000
o
or 360
o

NNE 022.5
o

NE 045
o

ENE 067.5
o

East 090
o

ESE 112.5
o

SE 135
o

SSE 157.5
o

South 180
o

SSW 202.5
o

SW 225
o

WSW 247.5
o

West 270
o

WNW 292.5
o

NW 315
o

NNW 337.5
o

245

Steps to find the bearing
Identify the points in question, for example, X and Y.
Draw a line using pencil to join X and Y. If the
distance between the two points is very short, extend
the line through the two points.
Through point X from which the bearing is required,
draw a pencil line pointing to the true north and at
right angles to it draw another line running east-west.
Align the protractor at X and in a clockwise direction
and measure the angle from the north to the one
joining X and Y.
State the bearing in degrees for example the bearing
of Y from X is approximately 312
o
.
Use the compass to find the nearest direction; for
example, Y is north west of X.
246

Cont‟d
Therefore, the bearing of Y from X in the above figure is 312
o
North West 247

Cont‟d
248

Cont‟d
If your declination is east then magnetic north is
greater than true north the map bearing is
greater than the magnetic bearing.
Map Bearing = Magnetic bearing + Declination.
249

Cont‟d
250

State the bearing of the point P in each of the
following diagrams
251

Find the bearing of A from B and B from
A, using the diagram below?
252

Chapter 7

Slope, Gradient and Contour types
253

Lesson 7.1: Slope and Gradient, Contour
Types
Slope is the steepness or gentleness of the land surface
It plays vital role in the life of landscape.
It determines the drainage pattern
It influence the transportation and communication, construction &
settlement.
Irrigation canals are influenced by slope.
Flora and fauna of the land is influenced by slope
Therefore, the analysis and its representation of slope are
important.
254

Cont‟d
How can we show slope on the map?

The most obvious method is to express slope on some kind of map
by contour line.

Contours further apart represent a gentle slope and on the other
hand contours closer to each other represent steep slope.
255

Cont‟d
There are four types of slope and they are presented as
follow.
1.Uniform slope
2.Convex slope
3.Concave slope
4.Undulating slope
1) Uniform Slope
In a uniform slope, the degree of slope is the same
throughout. The slope, therefore, remains unchanged.
Uniform slope is shown by contour lines which are
equi-spaced and sometimes called even slope. 256

1.Uniform Slope shown by contour line & its
cross section
257

2. Convex Slope
A convex slope is marked by an outward bulge.
The slope rises more steeply at the foot but less
steeply or more gently at the top.
This means that the degree of slope is greater at
the foot and less at the top.
The contour lines which represent a convex
slope are, therefore, close together at the foot
and are comparatively wide apart at the top.

258

2. Convex Slope shown by contour line & its
cross section
259

3. Concave Slope
A concave slope is marked by an inward bend on
relief feature. It is thus just the opposite of a
convex slope.
The slope is less at the foot but more at the top.
Contour lines are therefore, drawn comparatively
far apart at the foot and closer together at the
top.
The wide valleys (e.g., V-shaped valleys) and the
hanging valleys are representative examples of
the concave slopes.
260

3. Concave Slope shown by contour
line & its cross section
261

4. Undulated Slope
An undulating slope is irregularly marked by
outward bulges and inward bends.
 Its contour lines are variably spaced, i.e., there
is no uniform spacing between the consecutive
contour lines.
In general it shows the combination of concave
and convex slope
262

3. Undulated Slope shown by contour
line & its cross section
263

Cont‟d
In general term,
when contour lines are widely separated, they
represent gentle slope.

When contour lines are drawn closer together,
they represent steep slope.

If the vertical interval is high the slope is steep
and if it is small the slope is gentle
264

Methods of slope expression
Slope is expressed by degree, gradient and
percent.
1. By degree
It can be obtained by the help of protractor or
trigonometrically.
Suppose in the right angled ABC, AC represents
the slope distance. CB is the horizontal
equivalent and AB is the vertical interval.
The angle ACB will represent the slope in
degrees, and can be measured with the help of
protractor. 265

2. By Gradient
Slope can be represented using gradient.
 It is actually the ratio between the vertical
height (V.I) and the horizontal distance (H.E).
Example, If V.I. = 5feet and H.E. = 10 feet, the
gradient will be 5/10 = ½ which indicates a rise of
1feet after 2 feet horizontal distance.
Note that if the denominator becomes large
number, it represents that the slope of the
gradient is gentle.

266

3. By Percent
 If we multiply the gradient by 100, we shall
get the slope in percent,
Percentage of slope = V.I. x 100
H.E.
If some one needs to find out the gradient
from the given angle slope, the angle of the
slope is normally divided by 60 (or more
accurately 57.3) and the numerator is made
unity (1), e.g., for a slope of 3
o
, the gradient
will be 3/60 = 1/20.
267

Examples of Standard slopes
Angle of Slope Gradient Description of
slope
remark
Less than 1
o
1/60 Gentle Steel railway gradient
1
o
to 3
o
1/60 to 1/20 Moderate Cyclist walk
3
o
to 6
o
1/120 to 1/10 Stiff Horse driven vehicles proceed at a
walk.
6
o
to 12
o
1/10 to 1/5 Steep Cars find gradient difficult, have to
change gear.
12
o
to 20
o
1/5 to 1/3 Very steep
Horses descend obliquely on slopes greater
than 15
o
and horse drawn vehicles can not
ascend.
20
o
to 30
o
1/3 to 1/2 Very steep Limit for car
Over

30
o
Over 1/2 Precipitous Man can ascend using his feet and
hands.
268

Types of Contour lines
Contour lines are lines that connect the same
elevation.
Contour lines are the most common method of
showing relief and elevation on a standard
topographic map.
A contour line represents an imaginary line on
the ground, above or below sea level.
All points on the contour line are at the same
elevation.
269

Cont‟d
(1)Index. Starting at zero elevation or mean sea level, every
fifth or tenth contour line is a heavier line. These are
known as index contour lines. Normally, each index
contour line is numbered at some point.
(2)Intermediate. The contour lines falling between the index
contour lines are called intermediate contour lines.
These lines are finer and do not have their elevations
given. There are normally four or nine intermediate
contour lines between index contour lines.
(3) Supplementary. These contour lines resemble dashes or
broken line. They show changes in elevation of at least
one-half the contour interval. These lines are normally
found where there is very little change in elevation, such
as on fairly level terrain.
270

Diagrammatic representation of contour
271

Traficability of slope
Slope has a significant impact on movement
Some areas are more conducive for road construction than
others
Different modes of transportations have different slope
requirements

272

Gradient of different transport systems
Train = 2%
Bicycle = 10%
Car = 25 %
Man = 45 %
273

Intervisibility
Two places are intervisible when they are mutually seen.
E.g. point A can be seen from point B and Point B can be
seen from point A
This is very important for military analysis i.e for defensive
and offensive purpose
Intervisibility can be affected by:
274

Intervisibility
Slope
Vegetation cover
Buildings
High altitudes
Atmospheric conditions
Distance if it is out of range of vision
275

Dead land:

Dead land:
A land which is not visible from a certain selected point in the
field is called a dead ground from that point of view
It can be seen from one point but not from the other
276

Lesson 7.5: Relief representation and
Cross section
Relief is the shape of the ground surface
Relief on a map is shown by:
1.Layer Tinting: Layer tinting is a method of
showing relief by color. A different color is used
for each band of elevation.
2.Relief Shading: Relief shading indicates relief
by a shadow effect achieved by tone and color
that results in the darkening of one side of
terrain features, such as hills and ridges. The
darker the shading, the steeper the slope.
277

Cont‟d
3. Hachures: Hachures are short, broken lines
used to show relief.
278

Cont‟d
4. Spot height: The height that has been precisely
measured above mean sea level on the surface and
shown on the map by dots with heights in figures. In any
topographical maps, you will find the spot heights with
brown color dot.
5. Bench marks: A mark made by surveyors to record a
point of known position and height above mean sea
level. The mark is a cut into a permanent feature.
On the map these are indicated by letter by the letters
B.M. and the heights in figure.
6. Trigonometrical station: These are indicated on
maps by a small triangle with the heights in figures
above sea level. The points are used for
triangulation survey
279

Cont‟d
6. Contours: Contour lines are a method of
depicting the 3-dimensional character of the
terrain on a 2-dimensional map.
Contour lines are the most important and
standard methods of representing relief.
280

Examples of Trigonometric station and spot
height, & contour line
281

Cross Section/profile
Contouring is one of the most important methods to
represent the relief features.
Contour provides two dimensional view of relief.
A topographic profile is a cross-sectional view along a
line drawn through a proportion of a topographic map
It is the steepness or shape of the land scape along a
linear features like road, river and the like

282

Procedures
Draw a straight line which divides the contours a midst
Prepare a framework for the relief . The frame works are:
The base line (H.L): the line printing altitudinal values
horizontally.
The vertical line: for printing altitude values from the lowest to
the highest vertically
283

To make the vertical altitudes more visible/more
realistic/ we use vertical exaggeration /enlargement
scale/
The cross section has two scales;
The vertical scale is greater than the horizontal scale
because we exaggerate it to get a realistic picture
The horizontal scale: is the same as the map scale it
determines the distance of consecutive contours.
Vertical scale = horizontal scale/scale of the map/
vertical exaggeration

284

Label each mark with the elevation of the contour it
represents.

Prepare a vertical scale on profile paper by labeling
the horizontal lines corresponding to the elevation of
each contour line.

Place the paper with the labeled contour lines at the
bottom of the profile paper and project each contour
to the horizontal line of the same elevation.

Finally connect the points.

285

Cross Sectional profile of Hill
286

Cross Sectional profile of V-Shape Valley
287

Cross Sectional profile of U-Shape Valley
288

Cross Sectional Profile of Saddle
289

Cross Sectional Profile of Cliff
290

Vertical Exaggeration
when graphing distances and heights on one
graph, it is necessary to report the vertical
exaggeration of the cross-section.
Vertical exaggeration simply means that your
vertical scale is larger than your horizontal
scale.
vertical exaggeration is needed to show how
much the vertical scale has been exaggerated
to show the details of changes in elevation.
Without vertical exaggeration, the profile may
be so shallow that only the highest peaks
stand out.
291

Cont‟d
To determine the amount of vertical exaggeration
used to construct a profile, simply divide the real-
world units on the horizontal axis by the real-
world units on the vertical axis.
Example:
If the vertical scale is one 1cm=100m and the
horizontal scale is 1cm=2000m, the vertical
exaggeration is 20times (2000m/100m).
292

Examples of Vertical exaggeration graph
From the above graph, one unit (1cm) on the horizontal scale
represents 1000 m and one unit (1cm) on the vertical scale represents
50 m.
293

Cont‟d
Thus the vertical exaggeration of the above is:

This means that the vertical scale is 20 times more
exaggerated than the horizontal scale: 20 units on
the vertical scale represent the same distance/height
as one unit on the horizontal scale.
 20
50
1000
m
m
Vertical
Horizontal
VE
294

Lesson 7.7: Graphical Representation of
Thematic Maps, Graphs and diagrams
Thematic maps are data maps of a specific
subject or for a specific purpose.
Statistical thematic maps include a variety of
different thematic map types such as
choropleth or shaded maps, dot maps, flow
line maps, and isopleths maps.
Another graphical representation of
geographical data is by means of diagrams,
graphs, cartogram and proportional symbol
maps.
295

Cont‟d
During the production of the map, one has to know the
following conventional colors used every where:
Black - man-made features such as roads, buildings,
etc.
Blue – water bodies, lakes, rivers, streams, etc.
Brown - contour lines, spot heights.
Green - areas with substantial vegetation (could be
forest, scrub, etc.)
White - areas with little or no vegetation; white is also
used to depict permanent snowfields and glaciers
Red - major highways; boundaries of public land
areas
Purple - features added to the map since the original survey
296

The four most common types of Thematic maps
1.Choropleth map: It is based on numerical data
on some topic. For example, density
information, expressed as "per unit area," is
appropriately represented using a choropleth
map.
2.Dot Maps: It is most convenient method for
representing absolute quantities or numbers on
a map. Each dot is taken to represent a certain
quantity, and therefore, the number of dots to
be placed in an area, can be easily determined.
Example A dot might represent 1000 people. 297

Choropleth map
298

Dot Map
299

3. Isopleths Map
 This is using line symbols to portray a
continuous distribution such as
temperature, pressure or elevation etc.
Isolines are lines that connect points of
equal numeric value, e.g. Isobar, Isohyets,
contour lines, Isotherms etc.
Isopleths are not quite popular for
showing population distribution.
300

Isopleths Map
301

4. Flow line maps:
These types of maps represent the flow direction
of phenomena by giving different weight of the
lines.
Fore example, the flow direction of Main River &
minor rivers can be given different thickness of
lines.
Another good example can be the migration flow
of inhabitants
302

Flow line map
303

Graphs and Diagrams
Graphs are generally drawn to show the
relationship between two variables, one of them
being the number of students, or amount of
rainfall, or other to be shown is the time.
This relationship can be graphically represented
by the line graph or bar graph.
Moreover, diagrams like pyramid, proportional
symbol maps and cartogram are helpful to
represent geographical data graphically.
304

Line Graph
305

Bar Graph 40
6
12
14
6
2
0
5
10
15
20
25
30
35
40
Number of Stele
NO_Stele
NO_Fallen
NO_Brocken
NO_Burried NO_Inclined
NO_Errected
Physical Condition
Physical Condition of Stele in Geza Agumai
Stele Field
306

Pie chart Proportion of Students in Social Science
Departments at MU
25%
10%
20%
30%
10%
5%
Geography
History
English
Civics
Amharic
Tigrigna
307

Proportional Symbol map
 As the name implies, these maps scale
icons (most often circles) according to the
data they represent.
Proportional symbol map also use a point
symbol, but the symbols have different sizes
in proportion to some quality that occurs at
that point.
The populations of different cities are
frequently depicted on graduated circle
maps.
308

Proportional Symbol map
309

Cartography and GIS: Principles of Map Design, Coordinate Systems, and Projections

About This Presentation

Slide Content

Tags

Categories

Download

Quick Actions

Statistics

Related Slideshows

Cartography and GIS: Principles of Map Design, Coordinate Systems, and Projections

About This Presentation

Slide Content

Slide 1

Slide 2

Slide 3

Slide 4

Slide 5

Slide 6

Slide 7

Slide 8

Slide 9

Slide 10

Slide 11

Slide 12

Slide 13

Slide 14

Slide 15

Slide 16

Slide 17

Slide 18

Slide 19

Slide 20

Slide 21

Slide 22

Slide 23

Slide 24

Slide 25

Slide 26

Slide 27

Slide 28

Slide 29

Slide 30

Slide 31

Slide 32

Slide 33

Slide 34

Slide 35

Slide 36

Slide 37

Slide 38

Slide 39

Slide 40

Slide 41

Slide 42

Slide 43

Slide 44

Slide 45

Slide 46

Slide 47

Slide 48

Slide 49

Slide 50

Slide 51

Slide 52

Slide 53

Slide 54

Slide 55

Slide 56

Slide 57

Slide 58

Slide 59

Slide 60

Slide 61

Slide 62

Slide 63

Slide 64

Slide 65

Slide 66

Slide 67

Slide 68

Slide 69

Slide 70

Slide 71

Slide 72

Slide 73

Slide 74

Slide 75

Slide 76

Slide 77