AI8702 -REMOTE SENSING AND

GEOGRAPHICAL INFORMATION
SYSTEM

Mrs. Sujiitha R
CONTENTS

 GIS Definition
 History and Development of GIS

 Components of GIS

 Hardware and Software

 GIS (GEOGRAPHICAL INFORMATION SYSTEM)
 GIS is basically a computerized information system like
any other database, but with an important difference: all
information in GIS must be linked to a geographic
(spatial) reference (latitude/longitude, or other spatial
coordinates).
 GIS-DEFINITION
 The United States Geological Survey (USGS)
definition of GIS:
“A GIS as a computer hardware and software system
designed to collect, manage, analyze and display
geographically (spatially) referenced data.”
 Chang, 2010, definition of GIS:
“A Geographic Information System (GIS) is defined
as a computer system which is used for capturing,
storing, managing, querying, analysing and
displaying geospatial data.”
 Geospatial data also called as geographically
referenced data describes both the locations and the
characteristics of spatial features such as rivers,
roads, canals, land parcels, vegetation covers, on the
surface of the Earth.
 WHAT A GIS CAN DO?
There are five basic questions which a complete
GIS must answer. These are:

⚫ What exists at a particular location?

⚫ Where can specific features be found?
⚫ Trends or What has changed over time?
⚫ What spatial patterns exist?
⚫ Modelling or What if …?
COMPONENTS OF GIS
1. Computer Hardware Module
2. Computer Software Module
3. Data
4. Person
5. Methods
1. COMPUTER HARDWARE MODULE
 Hardware component of GIS includes all core and
peripheral equipment such as computer and operating
system to run a GIS.
 Purpose: Data input, storage, management, analysis
and display of geographic information.
 Personal computers which are mainly operating in the
windows system having central processing unit (CPU)
is opted for this purpose.
 CPU is like a heart of GIS hardware architecture, with
control over input/output connectivity with data
acquisition, storage and display systems.
 Storage units like hard disc drives are used to provide
space for storing data and programmes.
CONTD..
 The digital tape, cassettes, optical CDROMs, DVDs
and other devices are commonly used as storage
devices that can facilitate extra storage of data.
 Monitor is used for display.
 GPS receivers and mobile devices are used for
fieldwork.
 Devices like digitiser and scanner are used to convert
non-digital data such as maps and documents into
digital form, which later can be used in the computer
programmes.
 A plotter/printer is used to present the result of the
data processing in the form of hard copy.
2. COMPUTER SOFTWARE MODULE
 GIS Software which includes programme is required
to drive various functions such as entry, storage,
processing, analysis, manipulation and display of
data (both spatial and non-spatial).
 GIS software is user friendly and cost effective.
 The main user interfaces in GIS are menus, command
lines, scripts and graphical icons.
 The extensions or add-ons will extend the capabilities
of GIS functionalities.
 The use of new technologies has enhanced the
capabilities of GIS and made GIS a smart machine for
geographical knowledge.
CONTD…
 Presently, it is possible to integrate GIS functions
and application software modules built using
programming languages such as Visual Basic for
Application (VBA), Visual C++ and Dot net, etc.
 Since 1990s open source GIS softwares (e.g., GRASS,
ILWIS) with potentiality of working on all major
platforms (Windows, Linux, etc.) are available.
 But these softwares have limitations and drawbacks
which are required to be addressed for the benefit of
users.
3. DATA
 Data is an important component of GIS.
 GIS data comprise various types of inputs.
 The data inputs are essential for GIS system to
produce information.
 Large volume of high resolution data are widely
available at affordable cost due to the recent
developments in remote sensing and GPS
technologies.
 In order to store and maintain large volumes of data
the use of database management system (DBMS) is
required.
Fig: Data input, transformation and output in GIS platform
CONTD..
 Data Input: It can be done with the use of many tools
such as scanners, mouse, digitiser, word processors and
spread sheets.
 Data Storage and Management: Storage and
management of geospatial data is programmed using
GIS software.
 Data Analysis and Transformation: Data analysis is
applied to data in order to achieve answers to the
questions asked to GIS. Basic requirement for data
transformation in GIS is to remove errors in data sets
and make them ready to match with other data sets.
 Data Output: The output and presentation of
geographical data is characterised by different output
devices. It may be presented as maps, tables and figures.
 4. PEOPLE
 People component in GIS represents the users.
 Based on the information needs and the way they
interact with the system, GIS users are classified as:
viewers, general users and GIS specialists (Lo and
Yeung, 2009).

Fig: People
component of GIS
CONTD..
 Viewers:
⚫ People who browse geographical database
for their referential information are called
viewers.
⚫ Viewers are the users whose primary
requirement is to easily access geographical
information using the system.
⚫ In general, they are not involved in the
design and development of GIS.
⚫ But they influence whether to accept or
reject the technology because they are the
larger class in people component of GIS.
CONTD..
 General Users:
⚫ People who use GIS for general purpose such as
for business, professional services and decision-
making processes are called general users.
⚫ Eg. scientists, engineers, lawyers, entrepreneurs,
administrators, planners, facility managers,
politicians and many others.
⚫ They use GIS for relatively simple spatial queries
to very complicated tempo-spatial modelling
depending on their requirements.
⚫ They are active users and have direct influence on
the successful use of GIS in an organisation
CONTD…
 GIS Specialists:
⚫ They are the people who plan and develop GIS
software.
⚫ Eg. GIS managers, database administrators, GIS
application specialists, system analysts and
programmers.
⚫ They develop GIS software according to the needs
of the above mentioned two groups of users
(viewers and general users) and provide technical
support to them.
⚫ Unlike viewers they play a direct role in
successful implementation of GIS technology in
an organisation.
5. METHODS
 GIS operates successfully according to a well
designed implementation of the plans and rules.
 Basically, plans and rules include the models and
operating practices.
 In many organisations, GIS is not optimally used in
spite of costly hardware and sophisticated software
packages since the organisational aspects are not
properly looked into.
 The people working in an organisation are also
important because they possess various skills to
handle and work with geographic data and run GIS.
 Even they can be able to design, programme and
maintain GIS..
Fig: Decision making pyramid
CONTD..
 With the advent of graphical user interface
(GUI), powerful and affordable hardware and
software and public digital data has broadened
the range of GIS applications and brought GIS
to the mainstream use.
HISTORICAL DEVELOPMENT OF GIS
 Before 1960: The GIS Dark Ages
⚫ Computer mapping was not developed.
⚫ Mapping was done on paper
 1960-1975: GIS Pioneering
⚫ Canadian Geographic Information Systems
(CGIS) was conceptualised and became
operational by Roger Tomlinson – Father of
GIS
⚫ 1973  Geographical Information Retrieval
and Analysis System (GIRAS) was developed
by US Geological Survey to analyse the land
use and land cover data.
CONTD…
 1975-1990: GIS Software Commercialization
⚫ The first vector-based GIS software was developed
by Environmental Systems Research Institute
(ESRI), California in 1982.
 1990-2010: User Proliferaton
⚫ Users started to adopt GIS technology in different
ways
⚫ 2009  Space Applications Centre (SAC) of Indian
Space Research Organisation (ISRO) in
collaboration with Scanpoint Geomatics,
Ahmedabad, has developed the first Indian GIS
software named as IGIS (Integrated GIS and Image
Processing Software).
CONTD..
 2010 onwards: The open source explosion
⚫ Amazing projects like QGIS are providing
any user with a computer with GIS software
⚫ TIGER data, Landsat data and even LiDAR
data is accessible to download for free.
⚫ The commercial GIS software products out
there seem endless.
 IMPORTANT TERMS
 Digitiser -Flat board used for vectorisation of any
map object.
 Plotter- A device used to present the result of the data
processing in the form of hard copy.
 DBMS – Database Management System -A software for
storing and retrieving user’s data while considering
appropriate security measures.
 GUI – Graphical User Interface – It is a form of user
interface that allows the user to interact with
electronic devices through icons and audio indicators
instead of text based ineterfaces.
 Esri -Environmental Systems Research Institute -Esri
is an international supplier of geographic information
system software, web GIS and geodatabase
management applications.
THANK YOU
AI8702 -REMOTE SENSING AND
GEOGRAPHICAL INFORMATION
SYSTEM

Mrs. Sujiitha R
CONTENTS

 Maps
 Elements of Map

 Projection and Coordinate systems

MAP
 Maps are the primary tools by which spatial
relationships and geographic data are visualized.
 Maps are important in geography because they show
how different features are related.
 Maps therefore become important documents.
 There are several key elements that should be
included each time a map is created in order to aid
the viewer in understanding the communications of
that map and to document the source of the
geographic information used.
MAP ELEMENTS

1. Data Frame
2. Title
3. Legend
4. Scale
5. Directional Indicator
6. Inset Maps
CONTD…
1. Data Frame
 The data frame is the portion of the map that
displays the data layers.
 This section is the most important and central
focus of the map document.
CONTD…

2. Title
 The most important element of the map for
acquiring information efficiently is the title.
 The title identifies the map area and the type of
map.
 Cartographers (those who makes study on map)
may list the title simply or artistically.
 Titles of maps typically appear at the top of the
map, but not always.
 CONTD…
3. Legend
 Another important feature on a map is the legend or
map key.
 Information needed to read a map is found in the map
legend.
 Most maps use symbols or colors to represent different
geographic features.
 The map legend helps determine what the symbols and
colors mean.
 The legend serves as the decoder for the symbology in
the data frame.
 Sometimes colors are used to identify certain areas on
a map.
 Cartographers also use creative symbols on maps.
 CONTD…
4. Map Scale
 Map Scale is the ratio of distances on map to distances
to on the surface of the earth.
 It is specified in verbal, numeric or graphical form on
all standard maps.

Fig: Verbal, numeric or graphical form of

representation of map scale

 The standard map scales are:

1:1000,000 Country level or State level
1: 250, 000 State or District level
1: 50,000 District level
1: 12,500 Micro level
 Survey of India maps are available at all the above
levels except the micro-level.
CONTD…
5. Directional Indicator
 Another common map element is a directional
indicator.
 A directional indicator on a map helps determine
the orientation of the map.
 Some cartographers place an arrow that points to
the North Pole on the map.
 This is a “north arrow.”

 Other maps indicate direction by using a “compass

rose,” with arrows pointing to all four cardinal
directions.
CONTD…

6. Inset Maps
 Some maps feature inset maps— smaller maps
on the same sheet of paper.
 Inset maps provide additional information not
shown on the larger map.
 Inset maps are drawn at a larger, more
readable scale.
 Inset maps usually feature areas of interest
related to the larger map.
 Inset maps are commonly used on tourist/travel
maps.
PROJECTION AND COORDINATE SYSTEMS
 A GIS is to be created from available maps of
different thematic layers (soils, land use,
temperature, etc.).
 Maps are in two-dimensions whereas the earth’s
surface is a 3- dimensional ellipsoid.
 Every map has a projection and scale.
 To understand how maps are created by projecting
the 3-d earth’s surface into a 2-d plane of an
analogue map, we need to understand the
georeferencing concepts.
CONTD…
 Georeferencing involves 2 stages:
1. Geographic Coordinate System (GCS):
Specifying the 3-dimensional coordinate
system that is used for locating points on
the earth’s surface.
2. Projected Coordinate System (PCS): Used
for projecting into two dimensions for
creating analogue maps
GEOGRAPHIC COORDINATE SYSTEM
 Cartographers and geographers trace horizontal and
vertical lines called latitudes and longitudes across
Earth's surface to locate points on the globe.
 Together, they form the Earth’s geographical
coordinates, and represent the angular distance of
any location from the center of the Earth. Both
latitudes and longitudes are measured in degrees (°)
and minutes (′).

Fig: Latitudes
and Longitudes
CONTD…
 CONTD…

 The traditional way of

representing locations on the
surface of the earth is in the 3-
dimensional coordinate system is
by its latitude and longitude.
 Distance between two points on
the 3-d earth’s surface varies
with latitude.
 The 3-d system therefore does
not provide a consistent measure
of distances and areas at all
latitudes.
CONTD…
 The true surface of the Earth is not the smooth
ellipsoid but is quiet uneven and rugged.
 The GCS which is the surface used for specifying the
latitude and longitude of a point on the earth’s
surface is also an approximation and a 3-d model of
the earth.
 Several standard models of the ellipsoid are available
to define the GCS (WGS 84, Everest ellipsoid) etc.
 The ellipsoid model that is used to calculate latitude
and longitude is called the datum.
 Changing the datum, therefore, changes the values of
the latitude and longitude.
CONTD…

 Specifying the Geographic Coordinate System

therefore requires specifying the Datum.
 The datum is a fixed 3-d ellipsoid that is approximately
the size and shape of the surface of the earth, based on
which the geographic coordinates (latitude and
longitude) of a point on the Earth’s surface are
calculated.
 In fact describing a place by its lat/long is not complete
without specifying its datum.
 In India the Everest Ellipsoid (Everest Spheroid) is
used as the Datum for the Survey of India maps.
PROJECTED COORDINATE SYSTEM
 The development of GIS starts with an available
map on paper (an analogue map).
 This map therefore represents a projection of a 3-d
GCS in 2-dimensional form.
 CONTD…
 Projection is a mathematical transformation used to
project the real 3-dimensional spherical surface of the
earth in 2-dimensions on a plane sheet of paper.
 The projection causes distortions in one or more spatial
properties (area, shape, distance, or direction).

 CONTD…
 There are many methods of map projections, since
there are an infinite number of ways to project the 3-d
earth’s surface on to a 2-dimensional planar surface.
 The 3-d to 2- d projections can be done to a plane or to
the surface of a cone or cylinder leading to azimuthal,
conic or cylindrical projections respectively with many
variations.
 Depending on the scale and the agreeable tradeoffs
with respect to distortions, a specific projection form is
chosen.
 In India, the polyconic projection is commonly used by
Survey of India (SOI).
 All SOI toposheets* are in the polyconic projection.
*Toposheets - A kind of map that shows the topographic features of an area.
CONTD…
THANK YOU
AI8702 -REMOTE SENSING AND
GEOGRAPHICAL INFORMATION
SYSTEM

Mrs. Sujiitha R
CONTENTS

 Sources of GIS Data

 SOURCES OF GIS DATA

⚫ GIS represents geographic data and map

information as data layers.
⚫ The most important and expensive component of
the Geographic Information System is Data
which is generally known as fuel for GIS.
⚫ GIS data is combination of graphic and tabular
data.
⚫ Perhaps the most important component of a GIS
is the part of data used in GIS.
⚫ The data for GIS can be derived from various
sources.
 CONTD…
⚫ A wide variety of data sources exist for both spatial and
attribute data.
⚫ People can use topo maps, aerial photographs, satellite
images, data of ground surveys, readily available reports
and government or research publications.
⚫ Attribute data is information appended in tabular format
to spatial features.
⚫ The spatial data contains the information about the
‘where’ and attribute data can contain information about
the ‘what’, ‘where’, and ‘why’.
⚫ Attribute data provides characteristics about
spatial data.
SOURCES OF SPATIAL DATA
The most general sources for spatial data are:
⚫ hard copy maps
⚫ aerial photographs
⚫ remotely-sensed imagery
⚫ point data samples from surveys
⚫ existing digital data files.

 Existing hard copy maps, e.g. sometimesreferred

to as analogue maps, provide the most popular
source for any GIS project.
CONTD…
 USGS : U.S.Geological Survey
 CENSUS BUREAU
 NOAA : National Oceanic and Atmospheric
Administration
 EPA : Environmental Protection Agency
 NASA
 The Center for Advanced Spatial Technologies
(CAST) – Univ. of Arkansas
 NCAR : National Center for Atmospheric Research
 United Nations
 UKBORDERS: Digitized Boundary Data of U.K.
 ERIN Spatial Data (Australia)
SOURCES OF ATTRIBUTE DATA
⚫ Attribute data has an even wider variety of
data sources.
⚫ They are:
 GIS Data from Libraries,
 Data from National and International

Mapping Agencies
 Elevation Data

 Bathymetry Data

 Georeferenced Images,

 Time Series Multispectral Satellite Images

 State and national agencies

 Detailed District/ Municipal Data.

 Bathymetry is the study of underwater depth of

ocean floors or lake floors.
THANK YOU
AI8702 -REMOTE SENSING AND
GEOGRAPHICAL INFORMATION
SYSTEM

Mrs. Sujiitha R
CONTENTS

 Maps and their influences

 Characteristics of Maps
 MAPS AND THEIR INFLUENCES
 A map is the graphical two dimensional representations
of all or part of the Earth’s surface and its features on a
plane surface drawn to a specific scale.
 Since, it is also impractical to represent all features of
the Earth’s surface in their actual sizes and forms on a
map, maps are drawn at reduced scales.
 This attempt to show the surface of the Earth or a
portion of the Earth on a flat surface is known as map.
 Map projections help to represent the three-
dimensional features of the Earth’s surface in two-
dimensional forms.
 The word ‘Map’ is derived from the Latin word ‘Mappe’
which means Napkin of cloth cover.
CONTD…
 With the help of scales and map projections a
correspondence of every point on the map to the
actual ground position can be established.
 In a map, the real-world features have been
replaced by symbols, signs, shades and colors.
 In other words, maps are really selective,
symbolized and generalized representation of
real-world phenomena on a plane surface at a
reduced scale.
 Maps, therefore, are the paper storehouses of
geospatial information.
 Maps are mainly prepared and published by the
national mapping organization of every country of
the world.
BASED ON SCALE

1. Large Scale Map:

 A map which shows a small area with detailed
information is referred to as a large scale map.
 Large scale maps represent an area in higher
detail; thus, map may contain more information
but coverage of an area is small.
E.g. Survey of India maps at a scale of 1:25,000
CONTD…
 a. Cadastral Maps:
 The term ‘cadastral’ is derived from the French word
‘cadastre’ which means ‘register of property’ are
related to land.
 These maps are drawn on a very large scale such as
1:3,960, 1:1,900 or even more.
 They are used to show the ownership of land
properties by demarcating the boundaries of
agricultural fields and buildings.
 Cadastral maps are prepared and compiled by the
government agencies and are used for revenue and
taxation purposes.
CONTD…

b. Topographical Maps:
 Topographical maps are drawn on a scale relatively
smaller than cadastral maps.
 Topographic maps are based on precise
topographical surveys and are published in the form
of series of maps by the national mapping agencies.
 These maps are drawn at different scales, like
1:250,000; 1:50,000; 1:25,000 by the various mapping
agencies.
 A topographical map, for example, shows only
natural and cultural features and does not show the
boundaries of individual agricultural lands.
CONTD…

2. Small Scale Maps:

 Small scale maps refer to maps on which
objects are relatively small.
 They are drawn to show large areas e.g. a
map of the world that fits on one/two page
would be a small scale map.
CONTD…

a. Wall Maps:
 Wall maps are usually drawn on large size papers or
plastic sheets.
 After unfolding these maps you can hang on the wall.

 Wall maps look like posters

 Wall maps are small and simple, and used for many
purposes.
 They are used in classrooms, lecture halls, and also
help to navigate highways, roads, and locations.
 Scale for these maps is smaller than those of
topographical maps.
CONTD…

b. Atlas Maps:
 These maps are generally drawn on a very
small scale.
 Therefore, they represent large areas and also
provide highly generalized information of
physical and cultural features of different
regions of the world.
 Scale of atlas maps is smaller than wall maps.
 BASED ON FUNCTION
1. Physical Maps
 Prepared to show natural features such as heavenly
bodies, relief, soils, rocks, vegetation, drainage,
weather, climate, etc.
a. Astronomical Maps: Maps prepared to show
heavenly bodies, like stars, galaxies, or surfaces of
the planets and the Moon.
b. Relief Maps: Drawn to show the actual relief
(topography) features of surface of the Earth, like
mountains, valley, plains, plateaus, drainage, slopes,
river systems, etc.
c. Geological Maps: Prepared to show different types
of rocks, minerals, and geological structures.
CONTD…
d. Climatic Maps: Depict different types of
climate zones of an area.
e. Weather Maps: Drawn to show the average
conditions of weather’s elements
(temperature, pressure, rainfall, direction and
velocity of winds, etc.) over a short period,
which may range from one day to one season.
f. Soil Maps: Drawn to show different soil types
found in a region or continent using different
shades and colours.
g. Vegetation Maps: Prepared to show
distribution and types of vegetation in an
area, nation or the whole Earth.
CONTD…

2. Cultural Maps:
 Cultural maps are drawn to represent man-made
features such as buildings, canals, dams, rails and
road networks, etc.
a. Political Maps: Represent boundaries between
various political regions, such as tehsil, district,
state and country.
b. Population Maps: Drawn to show distribution and
density of population, and related features such as
growth rate, age and sex composition, religious
distribution, occupation, etc.
CONTD…

c. Economic Maps: Depict distribution and

production of agricultural, mining and industrial
products.
d. Transportation Maps: Drawn to show the network
of roads, railway lines, air and shipping routes.
e. Agricultural Maps: Represent production and
distribution of different types of crops in an area,
nation, or the whole world.
f. Industrial Maps: Drawn to show location of
industrial hubs in a region, nation or continent.
g. Historical Maps: Drawn to show past events.
DATA REPRESENTATION BY MAPS
 Generally, three types of data/designations are
represented in a map.
 These designations are given below:

 Point data
 Line data

 Polygon data/Area Data

CONTD…

 Point data consist of small and localised places on

a map whose surface extent is so small that names
cannot be placed within them e.g. cities, villages,
ports, towns, churches, mines, mountain peaks,
historical sites, triangulation points, etc.
 Line data refer to spatial features that have linear
or ribbon-like extent e.g. rivers, roads, railways,
canals, streets, ship routes, etc.
 Area data show a region on a map e.g. districts,
states, countries, lakes, oceans, bay, etc. An area
data is usually represented by closed boundaries
on maps in which names can be set
VISUAL ASPECTS OF MAPS

 It is important to choose appropriate symbols to

represent the geographic features on maps.
 A specific set of symbols that can be used to
communicate information is called visual
variables/visual aspects of maps (Bertin, 1967).
 Visual variables include location in space, shape,
size, orientation, hue (colour), and colour value.
 The visual variables are the building blocks for map
making.
 CONTD…
a. Primary Visual Variables
CONTD…

b. Secondary Visual Variables

 CHARACTERISTICS OF MAPS
1. A map is much smaller than the earth that it
represents. Altitudes, Longitudes and Scales are very
essential to draw maps.
2. Every map should have a bold title on the top. There
is an arrow mark in one corner of the map showing
north. With the help of this mark other directions are
known.
3. Index or legend is necessary for every map.
Universally accepted conventional symbols are used
on every map like RF (Reserved Forest), etc.
4. Maps are shaded with different colours also. White
indicates ice caps, Blue for water, Green for forest,
Yellow for agricultural belt, etc.
THANK YOU