1.
• Geographic Information System:
UNIT-III
For Training in GIS 1

2.
Geographic Information System
Compiled by
Prof SS.MANUGULA
B.Tech Civil., M.Tech RS
& GIS., (PhD)
GIS & RS Specialist
For Training in GIS 2
Objectives

3.
• Geographic Information System: Introduction to
GIS, Components of GIS, Geospatial Data- Spatial
Data, and Attribute data-Joining Spatial and
Attribute data: GIS Operation: Spatial Data Input-
Attribute data Management.-Data display- Data
Exploration- Data Analysis. COORDINATE SYSTEMS:
Geographic Coordinate System: Approximation of
Earth, Datum; Map Projections: Types of Map
Projection Map projection parameters-Commonly
used Map projections-Projected coordinate System.
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4.
Topics to be covered
• What is a GIS ?
• GIS as a Technology
• Components of a GIS
• GIS Tasks
• What GIS can do?
• Applications of GIS
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Next

5.
What is a GIS ?
A geographic information system (GIS), is an integrated set of
hardware and software tools used for the manipulation and
management of
• Spatial Data (geographic data) and
• Non Spatial Data (attribute data)
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GIS software
maintains a link
between layers of
location and
attribute data
Location Data- Where is it?
Attribute data- What is it?
With the link, we can ask
questions about our world….

6.
Components of a GIS
• A working GIS integrates
five key components:
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We commonly think of a
GIS as a single, integrated
computer system. But, GIS
can be made up of a
variety of software and
hardware tools.
The important factor is the
level of integration of these
tools to provide a smoothly
operating, fully functional
data processing
environment.

7.
Contd.......Components of a GIS
• DATA
• Data is perhaps the most important component of a GIS.
Geographic data and related tabular data can be collected in-house
& compiled to custom specifications, or purchased from a
commercial data provider.
• A GIS can integrate spatial data with other existing data resources,
stored in a DBMS. The integration of spatial data and tabular data is
a key functionality of GIS.
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Field Data
Computer Files Reports &
Tabular files
Maps
Digitization

8.
•Hardware is the computer
system on which a GIS
operates. GIS software runs on
a wide range of hardware types,
from centralized computer
servers to desktop PCs used in
stand-alone or network
configurations.
•GIS software provides the functions and tools needed to store, analyze,
and display geographic information. For e.g.-
•Arc View, Arc Info, Arc GIS, ERDAS, Global Mapper, Leica Photogrammetry
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DIGITAL TAPE
READER
DIGITIZER
TYPING
PC
WORKSTATION
NETWORK
DIGITAL DATA
PRINTER
PLOTTER
INPUT DATA
MANAGEMENT
OUTPUT
HARDWARE
SOFTWARE

9.
• PEOPLE
• GIS technology is of limited value without the people who
manage the system and develop plans for applying it to
real world problems. GIS users range from technical
specialists who design and maintain the system to those
who use it to help them perform their everyday work.
• METHODS A successful GIS operates according to a
well-designed implementation plan and business rules,
which are the models and operating practices unique to
each organization.
• As in all organizations, new tools can only be used
effectively if they are properly integrated into the entire
business operation. To do this properly requires not only
the necessary investments in hardware and software,
but also in the training and/or hiring of personnel to
utilize the new technology in the proper context.
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Components of a GIS
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Processes
Data
Hardware
The GIS
People
Software

11.
Thematic Layers
• A GIS stores information
about the world as a
collection of thematic
layers that can be linked
together by geography.
• The thematic layer
approach allows us to
organize the complexity of
the real world into a simple
representation to help
understand the natural
relationships.
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Geospatial Data
•(1.) Spatial data (stored in topology structure)Describes the absolute
and relative location of geographic features.
•(2.) Attribute data (stored in RDBMS)Describes characteristics of the
spatial features. These characteristics can be quantitative and/or
qualitative in nature. Attribute data is often tabular data.
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Attribute
Information:
What is it?
Species:
Oak
Height:
15m
Age: 75
Yrs
Location
Information:
Where is it?
51°N, 112°W
The coordinate location of a Land parcel would be spatial data, while its
characteristics, e.g. area, owner name, vacant/ built-up, etc., would be
attribute data.
GIS technology utilizes two basic types of data. These are:

13.
Copyright © Manugula Dy General Manager 1-13
Features linked to data
Each feature is
linked to an entry
in a data table
containing
information about
the feature.

14.
GIS Operations Tasks
(1.) DATA INPUT
• Before geographic data can be used in a GIS, the data must be
converted into compatible digital format through digitizing. The
data inputs are usually derived from a combination of hard copy
maps, aerial photographs, remotely sensed images, reports,
survey documents, etc.
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• Data Input
• Storage and Management,
• Manipulation and Analysis
• Data output (Visualization/display).
(2) STORAGE AND MANAGEMENT
This involves organizing the data (spatial and attribute), in a form
which permits it to be quickly retrieved by the user for analysis, and
permits rapid updates to be made to the database.
This component usually involves use of a DBMS for maintaining

15.
• For many types of
geographic operation
the end result is best
visualized as a map or
graph.
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The data output involves generation of graphic displays,
normally maps, and tables representing derived
information products that can be integrated with reports.
(4.)DATA OUTPUT
(Visualization/Display)

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Any spatial features of the Earth’s surface are
represented in GIS by the following:
•Area/polygons : features which occupy a certain
area, e.g. glacier units, lake units, land use units,
geological units etc.
• Lines/segments: linear features, e.g. drainage lines,
contour lines, boundaries of glaciers and lakes etc;
•Points : points define the discrete locations of
geographic features, the areas of which are too small
to illustrate as lines or polygons, e.g. mountain peaks
or discrete elevation points, sampling points for field
observations, identification points for polygon
features, centres of glaciers and lakes etc, and
attribute data refer to the properties of spatial entities

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SPATIAL DATA INPUT TECHNIQUES
The following are the basic procedures
for inputting spatial data into a GIS.
These are:
 Manual digitizing
 Automatic scanning
 Entry of coordinates using coordinate
geometry
 Conversion of existing digital data.

18.
Manual Digitizing
• Sends an electrical impulse
from the edges that is read
to determine Location.
• Accuracy of tablets ranges
form .01” to .002”
Manual digitising is the most common method of encoding spatial
features from paper maps. It is a process of converting the spatial
features on a map into a digital format. Point, line, and area
features that form a map, are converted into (x, y) coordinates.

19.
Digitizing Procedure
• Turn on digitizer and place map on tablet
– This will let the map and tablet reach thermal
equilibrium
• Tape the map to the tablet
• Register the map using control points
– Must have at least 4 control points with known
location
• Digitize the features
• Fix Digitizing errors (TOPOLOGY)

20.
Two Methods of Digitizing
• Point Mode
– One (X,Y) Location is captured for each click of the puck
button
– More accurate
– Requires less skill
• Stream Mode
– The digitizer will send locations while the puck button is
held down
– Requires more skill
– Can be faster
– Slow operators will capture many more points than
necessary

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On Screen Digitizing
The original is scanned and Geo referenced
Features are captured using the mouse

22.
Problems with Digitising Maps

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Scanner

24.
Automated Digitizing
• Tools to automatically convert a raster scan to vector
lines
• Requires a very clean scan
• Scans can be cleaned using raster cleanup tools
• The vector files usually require cleanup after
conversion
• If you start with a clean image it can save a lot of
time
• If you image is not clean manual digitizing may be
faster

25.
Raster to vector conversion

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Attribute Data
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• COORDINATE SYSTEMS
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Introduction:
• A map is a graphical representation of the location
of individual features on the surface of the earth.
• Since the surface is curved and the surface of the
map is a plane, it is difficult to represent a given
area with out some distortion.
• As the size of the area increases, the various types
of projections are employed to minimise the effect
of map distortion. On such a map, spherical co-
ordinates of control maps are used.
• The spherical coordinates of a point are its Latitude
and Longitude.
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29.
• Features on spherical surfaces are not easy to measure
• Features on planes are easy to measure and calculate
– distance
– angle
– Area
• Coordinate systems provide a measurement framework
• Lat/long system measures angles on spherical surfaces
• 60º east
• 55º north of equator
• 1° of longitude at the equator  1° of longitude near the
poles 30

30.
Geographic coordinate system
• A geographic coordinate system is a
coordinate system that enables every location
on the Earth to be specified by a set of
numbers or letters, or symbols. The
coordinates are often chosen such that one of
the numbers represents vertical position, and
two or three of the numbers represent
horizontal position.
• A common choice of coordinates is latitude,
longitude and elevation.
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31.
Approximation of Earth Datum;
• Definition of Datum: In surveying and geodesy, a datum is a
reference system or an approximation of the Earth's
surface against which positional measurements are made
for computing locations. Horizontal datum’s are used for
describing a point on the Earth's surface, in latitude and
longitude or another coordinate system.
• Commonly used datums in North
America
– North American Datum of
1927 (NAD27)
– NAD83
– World Geodetic System of
1984 (WGS84)
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32.
Map Projections:
• To specify a location on a two-dimensional
map requires a map projection
What is map projection?
• The system of representing the earth’s
parallel and meridian with respect to which
control points in spherical terms, are plotted
on the map is called a map projection.
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33.
Types of Map Projection
(a) Cylindrical-type projections
1. Perspective cylindrical projection
2. Simple cylindrical or cylindrical equidistant
projection
3. Cylindrical equal area projection
4. Mercator's projection (cylindrical orthomorphic)
5. Sinusoidal projection
6. Interrupted sinusoidal
(b) A compromise projection
1. Mollweide's projection
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34.
(d) Conical-type projections
1. Perspective conic projection
2. Simple conic projection: one standard parallel
3. Bonne's projection
4. Conic projection with two standard parallels
5. Polyconic projection
(c) Zenithal projections
1. Gnomonic projection
2. Stereographic projection
3. Orthographic projection
4. Zenithal equidistant projection
5. Zenithal equal-area projection
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35.
Map Projection parameters
• . The parameters specify the origin and customize a projection for
your area of interest. , linear parameters use the projected
coordinate system units, while angular parameters use the
geographic coordinate system units
• Linear parameters
• Angular parameters
• Unitless parameters
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36.
Linear parameters
• False easting is a linear value applied to the origin
of the x coordinates. False northing is a linear
value applied to the origin of the y coordinates.
False easting and northing values are usually
applied to ensure that all x and y values are
positive. You can also use the false easting and
northing parameters to reduce the range of the x
or y coordinate values. For example, if you know all
y values are greater than 5,000,000 meters, you
could apply a false northing of -5,000,000.
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37.
Angular parameters
• Azimuth—Defines the center line of a projection; the rotation angle measures east
from north. Azimuth is used with the Azimuth cases of the Hotine Oblique
Mercator projection.
Central Meridian—Defines the origin of the x-coordinates
Longitude of Origin—Defines the origin of the x-coordinates; the central meridian
and longitude of origin parameters are synonymous.
Central Parallel—Defines the origin of the y-coordinates
Latitude of Origin—Defines the origin of the y-coordinates; this parameter may
not be located at the center of the projection. In particular, Conic projections use
this parameter to set the origin of the y-coordinates below the area of interest. In
that instance, you do not need to set a false northing parameter to ensure that all
y-coordinates are positive.
Longitude of Center—Is used with the Hotine Oblique Mercator Center (both Two-
Point and Azimuth) cases to define the origin of the x-coordinates; usually
synonymous with the longitude of origin and central meridian parameters.
Latitude of Center—Used with the Hotine Oblique Mercator Center (both Two-
Point and Azimuth) cases to define the origin of the y-coordinates; it is almost
always the center of the projection.
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38.
Unitless parameters
 Scale factor is a unitless value applied to the center point
or line of a map projection.
The scale factor is usually slightly less than
one. The UTM coordinate system, which uses the
Transverse Mercator projection, has a scale factor of
0.9996. Rather than 1.0, the scale along the central
meridian of the projection is 0.9996. This creates two
almost parallel lines approximately 180 kilometers, or
about 1°, away where the scale is 1.0. The scale factor
reduces the overall distortion of the projection in the
area of interest.
x- and y-scales are used in the Krovak projection to
orient the axes. 39

39.
State Plane
 Codified in 1930s
 Use of numeric zones for shorthand
 SPCS (State Plane Coordinate System)
 FIPS (Federal Information Processing System)
 Uses one or more of 3 different projections:
 Lambert Conformal Conic (east-west orientation )
 Transverse Mercator (north-south orientation)
 Oblique Mercator (nw-se or ne-sw orientation)

40.
Universal Transverse Mercator
(UTM)
 Based on the Transverse
Mercator projection
 60 zones (each 6° wide)
 false eastings
 Y-0 set at south pole or equator

41.
Projected Coordinate Systems
 A Projected coordinate system
(PCS) is a two-dimensional planar
surface. However, the Earth's surface
is three-dimensional.
 Transforming three-dimensional
space onto a two-dimensional
surface is called projection.
 Projection formulas are
mathematical expressions that
convert data from a geographical
location (latitude and longitude) on a
sphere or spheroid to a
corresponding location (x and y) on a
flat,two-dimensional-surfaces. 42

42.
• A PCS inherits the components of a geographic
coordinate system and also has:
• Projection: The mathematical transformation used
to convert from geographic coordinates to planar
(projected) coordinates.
• Parameters: Parameters used in the
transformation. These parameters are specific to
the projection.
• Units: Linear measurement for coordinates on the
plane.
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43.
•THE END OF
UNIT III
Any Doughts
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44.
ASSIGNMENT-UNIT_1
• Short Answer Questions
• 1 Define Principle & Photogrammetry?
• 2 Types of Aerial Photos
• 3. Types of Aerial Photogrammetry?
• 4. Write short notes on fiducial points
• 5. What is Parallex?
• 6 What is stereoscopy?
• 7 Define the followings: Nadir Point, Pass
Point, tie point and control point, Principal
point For Training in GIS 45

45.
Essay Questions
1. Write the equation for finding Parallax of any point with
figure and also derive the equations for finding object height
and ground coordinate location from parallax measurement.
2. The flying height for an overlapping pair of photos is
1600m above the ground and Pa is 75.60mm. Find the
height of the tree if the parallax difference is 1.20mm.
3. Explain with sketch the Geometry of vertical aerial
photograph, Scale and Height measurement on single
vertical aerial photograph
4. Height measurement based on relief displacement
5 Define an aerial vertical photograph, an aerial tilted
photograph, a low oblique aerial photograph, and a high
oblique aerial photograph 46

46.
Data Types

47.
Relational Model
•Data is often stored in several
tables. Tables can be joined or
referenced to each other by
common columns (relational fields).
•Usually the common column (Field)
is an identification number for a
selected geographic feature, e.g. a
parcel number. This ID number acts
as the primary key for the table.
• The ability to join tables
through a common column is the
advantage of the relational model.
• Such relational joins form the basis
of querying in a relational GIS
product.
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48.
What can GIS do for you?
•(1.) Perform
geographic queries and
analysis
•Two types of analysis are especially
important
•Proximity analysis
•Overlay Analysis
•The ability of GIS to perform geographic
queries has saved many companies
millions of dollars. GIS has helped reduce
costs by Analyzing data quickly, as in this
example:
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A real estate agent could use a GIS to find all apartments within a certain area
(say Andheri) that have three bedrooms and are in high-rise buildings, then list
their information.
The query could be further refined by adding criteria like - the house must cost
less than 2000 Rs/sq foot & should be within walking distance from rail station.

49.
Proximity analysis
•It involves queries like-
 How many houses lie within 60m of this road?
 What is the total number of customers within 10 kms of this store?
 What proportion of Rice crop is within 500 m of the well?
•To answer such questions, GIS technology uses a process called
buffering to determine the proximity relationship between features.
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50.
What can GIS do for you?
•(2.) Improve organizational integration
•Many organizations that have
implemented GIS have found that its
main benefit is to improve management
of their own resources.
• Because GIS have the ability to link
data sets together, they facilitate
interdepartmental information sharing
and communication.
•One department can benefit from the
work of another as data can be collected
once and used many times.
•Thus redundancy is reduced and
productivity gets enhanced.
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51.
Overlay Analysis
•In GIS the integration of different data layers involves a
process called overlay. For e.g.-
•This overlay, or spatial join, can integrated data on soils,
slope, vegetation or land ownership with tax assessment.
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52.
What GIS can do?
• GIS has made map making much
more flexible than traditional manual
cartography. Existing paper maps can be
digitized and translated into the GIS.
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 The GIS based cartographic database can be both continuous and
scale free.
 Map products can then be created centered on any location, at any
scale and showing selected information theme.
(4.) Making
maps

53.
Applications of GIS
• Some of the real world applications of GIS are in:
• Urban Planning
• Agriculture
• Public Utilities
• Transportation
• Health Care
• Emergency
• Real Estate
• Marketing
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54.
Applications of GIS
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Is it safe to dig here?
A proposed excavation, identified by
address, is compared to pipelines in the area
using Geotechnology.
PUBLIC UTILITIES

55.
Applications of GIS
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Where is my Dream
Home?
With Geotechnology, an agent can
show a map of a neighborhood and a
picture or video of the actual
properties.
REAL ESTATE

56.
Applications of GIS
•EMERGENCY
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What is the fastest
route to the
Hospital?
Geotechnology can choose the
fastest route to a hospital. The
GIS can take into account
traffic and other impediments.

57.
Applications of GIS
•MARKETING
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How can I optimize
my Marketing
Campaign?
Geotechnology can query a database and
identify only those areas with the highest
household income within a specified distance
of a store.

58.
Topics covered
• What is a GIS ?
• GIS as a Technology
• Components of a GIS
• GIS Data Types
• GIS Tasks
• What GIS can do?
• Applications of GIS
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Back

59.
SPECIAL DESCRIPTIVE TEST
• PART - A
1. Answer all the following Questions :-(3 Marks)
• Define GIS? (1 M)
• Define Remote Sensing? (1 M)
• What are the different types of sensors?(1 M)
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60.
PART – B (7 marks)
Answer the following Questions:-
3. a) Explain with sketch the Geometry of vertical
aerial photograph, Scale and Height measurement on single
vertical aerial photograph. (4 marks)
. b) Write short note on digital data analysis. (3 marks)
OR
4. a) What is EMR? Discuss about spectral reflectance
patterns for different region of Electromagnetic spectrum,
with a neat diagram.
(3 marks)
b) Explain Spatial & attribute data in GIS. What are the
different applications in GIS explain? (4 marks)
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61.
•THANK YOU
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