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REMOTE SENSING- I
1.0. After going through this chapter, you will be able
to understand the following:
Unit Structure :
1.1 Objectives
1.2 Introduction
1.3 Subject Discussion
1.4 Geospatial technology: concept, components and importance.
1.5 Definition and Concept of Remote Sensing; History of
IndianRemote Sensing.
1.6 Concept of EMR and Electro -Magnetic Energy; Properties of EMR:
Wavelength and Wave Frequency; Electro -Magnetic Spectrum;
EMR interaction with atmosphere and Surface
1.7 Resolution: Spatial, Temporal, Spectral and Radiometric
1.8 Remote Sensing applications in Geography
1.9 Open Data sites of Remote Sensing: Explore/ Access/ open
Bhuvan website
1.10 Summary
1.11 Check your progress
1.12 Answers to the questions
1.13 Technical words and their meanings
1.14 Task
1.15 References for further study
1.1 OBJECTIVES
To understand the new Geospatial technology: concept, components
and importance.
To understand the concept and history of remote sensing
To understand the concept of EMR
To learn concepts like resolution and applications of remote sensing munotes.in
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2 1.2 INTRODUC TION
Geospatial Technology is the new era of technology it can be very used
full in geography, especially for geographic mapping purposes. Remote
Sensing is the collection of information relating to objects without being
in physical contact with them. Thus, our eyes and ears are remote sensors,
and the same is true for cameras and
microphones and for many instruments used for all kinds of applications.
Remote sensing is the process of acquiring data/information about
objects/substances not in direct contact with the sensor, by gathe ring its
inputs using electromagnetic radiation or acoustical waves that emanate
from the targets of interest. An aerial photograph is a common example of
a remotely sensed (by camera and film, or now digital) product.
1.3 SUBJECT DISCUSS ION
Remote sensing makes it possible to collect data on dange rous or
inaccessible areas. Remote sensing applications include monitoring
deforestation in areas such as the Amazon Basin, the effects of
climate change on glaciers and Arctic and Anta rctic regions, along
with depth sounding of coastal and ocean depths. Remote sensing also
replaces costly and slow data collection on the ground, ensuring in
the process that areas or objects are not disturbed.
1.4 GEOSPATIAL TECHNOLOGY : CONCEPT,
COMPONENTS AND IMPORTANCE
Geospatial technology is a term that describes the range of modern tools
contributing to the geographic mapping and analysis of the Earth and
human societies. These technologies have been evolving in some form
since the first maps were drawn in prehistoric times. In the 19th century,
the long important schools of cartography and mapmaking were joined by
aerial photogra phy as early cameras were sent aloft on balloons and
pigeons, and then on aeroplanes during the 20th century. The science and
art of photographic interpretation and map -making was accelerated during
the Second World War and during the Cold War it took on n ew
dimensions with the advent of satellites and computers. Satellites allowed
images of the Earth’s surface and human activities therein with certain
limitations. Computers allowed storage and transfer of imagery together
with the development of associated digital software, maps, and data sets
on socioeconomic and environmental phenomena, collectively called
geographic information systems (GIS). An important aspect of a GIS is its
ability to assemble the range of geospatial data into a layered set of maps
which allow complex themes to be analyzed and then communicated to
wider audiences. This ‘layering’ is enabled by the fact that all such data
includes information on its precise location on the surface of the Earth,
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3 Especially i n the last decade, these technologies have evolved into a
network of national security, scientific, and commercially operated
satellites complemented by powerful desktop GIS. In addition, aerial
remote sensing platforms, including unmanned aerial vehicles (e.g. the
Global Hawk reconnaissance drone), are seeing increased non -military use
as well. High quality hardware and data is now available to new audiences
such as universities, corporations, and non -governmental organizations.
The fields and sectors depl oying these technologies are currently growing
at a rapid pace, informing decision makers on topics such as industrial
engineering, biodiversity conservation, forest fire suppression, agricultural
monitoring, humanitarian relief, and much more.
There are n ow a variety of types of geospatial technologies potentially
applicable to human rights, including the following:
Remote Sensing: imagery and data collected from space - or airborne
camera and sensor platforms. Some commercial satellite image
providers now offer images showing details of one meter or smaller,
making these images appropriate for monitoring humanitarian needs
and human rights abuses.
Geographic Information Systems (GIS): a suite of software tools for
mapping and analyzing data which is georefe renced (assigned a
specific location on the surface of the Earth, otherwise known as
geospatial data). GIS can be used to detect geographic patterns in other
data, such as disease clusters resulting from toxins, sub -optimal water
access, etc.
Global Positi oning System (GPS): a network of U.S. Department of
Defense satellites which can give precise coordinate locations to
civilian and military users with proper receiving equipment (note: a
similar European system called Galileo will be operational within the
next several years while a Russian system is functioning but
restricted).
Internet Mapping Technologies: software programs like Google Earth
and web features like Microsoft Virtual Earth are changing the way
geospatial data is viewed and shared. The devel opments in user
interface are also making such technologies available to a wider
audience whereas traditional GIS has been reserved for specialists and
those who invest time in learning complex software programs.
1.5. DEFINITION AND CONCEPT OF REMOTE
SENS ING
Definition: Remote sensing is the acquisition of information about an
object or phenomenon without making physical contact with the object.
The term "remote sensing" generally refers to the use of satellite-
or aircraft-based sensor technologies to detect and classify objects
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4 oceans, based on propagated signals (e.g. electromagnet ic radiation).
It may be split into "active" remote sensing (i.e., when a signal is
emitted by a satellite or aircraft and its reflection by the object is
detected by the sensor) and "passive" remote sensing (i.e., when the
reflection of sunlight is detected by the sensor).
Electro-magnetic radiation which is reflected or emitted from an
object is the usual source of remote sensing data. However, any
media such as gravity or magnetic fields can be utilized in remote
sensing. A device to detect the electro-magnet ic radiation reflected or
emitted from an object is called a "remote sensor" or "sensor". Cameras
or scanne rs are examples of remote sensors. A vehicle to carry the
sensor is called a "platform". Aircraft or satellites are used as
platforms. The technical term "remote sensing" was first used in the
United States in the 1960's, and encompassed photogrammetry, photo -
interpretation, photo-geology etc. Since Landsat-1, the First earth
observation satellite was launched in 1972; remote sensing has become
widely used. The characteristics of a n object can be determined; using
reflected or emitted electro -magnetic radiation, from the object. That is,
"each object has a unique and different characteristic of reflection or
emission if the type of deject or the environmental condition is
diffe rent.” Remote sensing is a technology to identify and
understand the object or the environmental condition through the
uniqueness of the reflection or emission.
History of Indian Remote Sensing
Remote sensing has been with us for longer than you may think. In the
1600 Galileo used optical enhancement to survey celestial bodies.
Photographer Gaspard Felix Tournachon attempt ed to perform land
surveys in 1859 using photos taken from balloons.
Development of Remote Sensing in India from Years 1975 – 2017
1) Aryabhatta satellite was launched in the year 19 April 1975
2) Bhaskar Segal satellite was launched in the year 7 June 1979
3) Rohini RS – 1 satellite was launched in the year 18 July 1980
4) Bhaskar – II satellite was launch in the year 20 November
5) INSAT - 1B Satellite was launched in the year 30 August 1983
6) Stretched Rohini Satellite Services (SROSS - 1) satellite was
launched in the year 24 March 1987
7) IRS – IA Satellite was launch in the year 17 March 1988
8) INSAT – IC satellite was launch in the year 12 June 1990
9) 1RS – 1 N satellite was launch in the year 29 August 1991 munotes.in
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5 10) Stretched Rohini Satellite Series (SROSS C) was
launched in the year 20 May 1992
11) INSAT - 2B Satellite was launched in the year 23 July 1993
12) Stretched Rohini Satellite Series (SROSS – C2) was launched in
the year 4 May 1994
13) INSAT - 2D Satellite was launched in the year 4 June 1997
14) INSAT - 2E Satellite was launched in the year 3 April 1999
15) INSAT - 3B Satellite was launched in the year 22 March 2000
16) GSAT – 1 satellite was launched in the year 18 April 2001
17) EDUSAT Satellite was launched in the year 20 October 2004
18) Oceansat – 2 (IRS - P4) satellite was launched in the year 23
19) GSAT – 4 Satellite was launched in the year 15 April 2010
20) YouthSat satellite was launched in the year 20 April 2011
21) IRNSS – 1F Satellite was launched in the year 10 March 2016
22) Cartosat – 2D satellite was launched in the year 15 February
2017
23) Remote sensing is the process of acquisition of information
about objects or phenomenon without making physical contact with
the object and thus in contrast to on site observations. Remote
sensing is used in number of fields including Geography,
land surveying, and most earth science disciplines, it also has
military, intelligence, commercial, economic planning and
humanitarian applications. the process involved in remote sensing
is collection of data about an object from distance. Remote means
far away and sensing means getting information. Here sensors
are used to sense objects. The sensor records information about
an object by measuring the “ELECTROMAGNETIC ENERGY”
reflected back to the earth surface September 200
1.6. CONCEPT OF ELECTROMAGNETIC
RADIATION (EMR)
Electromagnet ic radiation (EM radiation or EMR) refers to the waves
of the e lectromagnetic field, propagating (radiating) through space
carrying electromagn etic radiant energy. It includes radio waves,
microwaves, infrared, (visible) light, ultraviolet, X-, and gamma
radiation.
Electromagnet ic waves are produced whenever charged particles are
faster, and these waves can subsequent ly interact with other charged
particles. Electromagn etic radiation is associated with those EM waves munotes.in
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6 that are free to propagate themselves ("radiate") without the continuing
influence of the moving charges that produced them, because they
have achieved sufficient distance from those charges.
Wave Length & Wave Frequency
Wavelength is a measure of the distance between repetitions of a
shape feature such as peaks, valleys, or zero- crossings, not a measure of
how far any given particle moves. The range of wavelengths or
frequencies for wave phenomena is called a spectrum. The name
originated with the visible light spectrum but now can be applied to the
entire electromagnetic spectrum as well as to a sound spectrum or
vibration spectrum. Wavelength is commonly designated by the Greek
letter lambda (λ).
Assuming that waves move at a fixed wave speed, wavelength
is inversely proportional to frequency of the wave: waves with
higher frequencies have shorter wavelengths, and lower frequencies have
longer wavelengths.
Examples of wave-like phenomena are sound waves, light, water
waves and periodic electrical signals in a condu ctor.
Electromagnetic Spectrum
The heat produced by the sun travels from the sun to the earth via
waves known as electromagnet ic waves. These waves can vary
greatly in their wavelength. The electromagnet ic waves coming to
earth from sun come in variety of lengths so scientists consider it as
spectrum. Thus, the waves all toget her are called as electromagnet ic
spectrum.
“The EMS is the continuum of all EM waves arranged according to
frequency and wavelength”. At one end of spectrum are the waves with
lowest frequencies. At the other end are highest frequency waves. The
spectrum is broken into regions that define each of the different wave
types.
Radio waves are the type of electromagnetic radiation with
wavelength in the electromagnetic spectrum longer than infrared light.
Naturally occurring radio waves are gene rated by radio transmitters
and received by radio receivers. These waves used for fixed and
mobile radio communication, broadcasting radar and other navigation
systems, communication satellites, compu ter network.
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7
An electromagnet ic wave with wavelength in the range 0.00-0.3m,
shorter than that of a normal radio wave but longer than those of
infrared radiation. Microwaves are used in radar, in communication
and for cooking in microwave ovens and in various industrial
processes.
Infrared radiation has longer wavelengths than those of visible
light. Infrared was discovered in 18 00 by astronomer SIR
W.HERSCHEL. These radiations are just beyond what our eyes can
detect on the red site of the rainbow. We are surrounded by infrared
every moment.
Visible light is defined as the wavelengths that are visible to most
human eyes these waves are seen as the colour of rainbow. Each
colour has different wavelength. Red has longest while violet has
the shortest wavelength .is the natural source for the visible light
waves and our eyes see the reflection of this sunlight of the objects
around us.
Ultra violet radiations shorter than that of visible light but longer
than x rays. It constitutes of 10% of the total light output of the
sun and it is present in the sunlight. These waves just beyond
what our eye can see beyond violet side of rainbow. Ultraviolet are
absorbed by the atmosphere particularly ozone layer UV rays can
be used in hospitals, UV lamps, to sterilize surgical equipment etc.
X-rays wavelengths are shorter than those of gamma rays. X-rays
are high in frequency and carries lots of energy. They pass through
most of the substances and are majorly used in medical industry.
The gamma rays have the high frequency high energy and are
shorter wavelengths rays. These rays are the product of radioactive
element.
EMR Interaction with Atmosphere and Earth Surface
The radiation from the energy source passes through some distance
before being detected by the remote sensors. The interaction of MR with
atmospheric particles may be a surface phenomenon (scattering) or
volume phenom enon. (absorption) Scattering and absorption are main
process that alters the properties of the EMR in atmosphere.
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8
Atmospheric scattering is the process by which small particles
in the at mosphere diffuse a portion of the incident radiation in all
direction. There is no transformation while scattering. But the
spatial distribution of the energy is altered during scattering. There
are three different types of scattering as follows:
1. Rayleigh sca ttering occurs when particles are very small
compared to the wavelength of the radiation. These could be particles
such as small specks of dust or nitrogen and
oxygen molecules. Rayleigh scattering causes shorter wavelengths of
energy to be scattered much more than longer wavelengths.
2. Mie scattering occurs when the particles are just about the same size
as the wavelength of the radiation. Dust, pollen, smoke and water
vapour are common causes of Mie scattering which tends to affect
longer wavelengths than those affected by Rayleigh scattering.
3. Non-Selec tive Scattering occurs when the particles are much
larger than the wavelength of the radiation.
Absorption is the process in which incident energy is retained
by particles in the atmosphere at a given wavelength. Unlike
scattering, atmospheric absorption causes an effective loss of
energy to atmospheric constituent s. The absorbing medium will not
only absorb a portion of the total energy, but will also reflect,
refract or scatter the en ergy. The absorbed energy may also be
transmitted back to the atmosphere. The most efficient absorbers of
solar radiation are water vapour, carbon dioxide, and ozone.
Gaseous compone nts of the atmosphere are selective absorbers of
the electromagnet ic radiation, i.e., these gases absorb electromagnetic
energy in specific wavelength bands.
1.7. RESOLUTION: SPATIAL, TEMPORAL,
SPECTRAL AND RADIOMETRIC
Resolution refers to the capability of distinguishing between two
separate but adjacent objects or sources of light or between two
nearly equal wavelength s. Resolution is a measure used to describe
the sharpness and clarity of an image or picture.
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9 There are 4 types of resolution as follows:
Spatial Resolution
A digital image consists of an array/ display of pixels. Each pixel
contains information about a small area on the land surface, which is
considered as a single object. Spatial resolution is a measure of the area
or size of the smallest dimension on the Earth’s surface over which
an independent measurement can be made by the sensor. It is expressed
by the size of the pixel on the ground in meters. Based on the spatial
resolution, satellite systems can be classified as low-resolution systems,
medium resolution systems, high resolution systems and very high-
resolution systems.
Temporal Resolution
Temporal resolution is defined as the amount of time needed to revisit
and acquire data for the exact same location. When applied to
remote sensing, this amount of time depends on the orbital
characteristics of the sensor platform as well as sensor characteristics. The
temporal resolution is high when the revisiting delay is low and vice-
versa. Temporal resolution is usually expressed in days.
Spectral Resolution
Spectral resolution represents the spectral band width of the filter and the
sensitiveness of the detector. The spectral resolution may be defined as
the ability of a sensor to define fine wavelength intervals or the ability of
a sensor to resolve the energy received in a spectral band width to
characterize different constituents of earth surface. The finer the spectral
resolution, the narrower the wavelengths range for a particular channel or
band.
Many remote sensing systems are multi-spectral, that record energy over
separate wavelength ranges at various spectral resolutions. In remote
sensing, different features are identified from the image by compa ring
their responses over different distinct spectral band s. Broad classes, such
as water and vegetation, can be easily separated using very broad
wavelength ranges like visible and near-infrared. However, for more
specific classes’ viz., vegetation type, rock classification etc., much
finer wavelength ranges and hence finer spectral resolution are required.
Radiometric Resolution
While the arrangement of pixels describes the spatial structure of
an image, the radiometric characteristics describe the actual information
content in an image. Every time an image is acquired on film or by
a sensor, its sensitivity to the magnitude of the e lectromagnetic energy
determines the radiomet ric resolution. The radiometric resolution of an
imaging system describes its ability to discriminate very slight
differences in energy. The finer the radiometric resolution of a munotes.in
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10 sensor the more sensitive it is to detecting small differences in
reflected or emitted energy.
1.8 APPLICATION OF REM OTE SEN SING IN
GEOGRAPHY
Forest cover mapping: Based on the sensing data forest cover
mapping to monitor forest cover changes is been carried on. In India,
this is done by forest survey of India.
Crop Average and Production Examination: Satellite Remote
sensing based, estimation of Crop Average and Production forecast
for major crop is carried on. This is very important for depa rtment of
agriculture.
Flood mapping: It is used in satellite data; mapping of the
flooded areas and estimation of damage is being carried out.
Mineral Exploration: Remote sensing is widely used to explore the
area of minerals.
Hazard assessment: For identifying different types of hazards and
hazard zones, Remote sensing is greatly used.
Ocean Resources: Coastal zones maps are prepared with the help of
Remote sensing.
Marine Resources: Fishery potential charts are being
gene rated using satellite data.
Water Quality Monitoring: Water pollution has become a very
serious problem in the industrial zones. Water Quality
monitoring is one of the typical application of remote sensing.
Measurement of sea surface temperature: Satellite Remote
sensing can provide thermal information as well.
Snow Survey: Aerial distribution of snow can be identified very
easily from satellite remote sensing data.
Soil mapping: Mapping of Saline and Alkaline soils is very
easily carried out using remote sensing.
Environm ental Impact Assessment (EIA): Satellite Remote
sensing data has been used to access the impact of different activities
like Mining, Agriculture, and Industries on the environment.
Urban Studies: Many new applications in urban studies have been
carried out with the help of available satellite data.
Monitoring oil spills: The location of political spills events can be
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11 Bathymetric Surveying: At present remote sensing is also used
for depth measurements and also to make bottom depth chart.
Land cover and land use map: Satellite data along with field
survey data can be combined to create land cover and land use map in
detail.
Monitoring Atmospheric Emissions: Software has been
developed so that satellite dates can be used to estimate natural
and polluting emissions.
1.9 OPEN DATA SITES OF REM OTE SEN SING:
EXP LORE/ ACCESS/ OPEN BHUVAN WEBSITE
Visit the websites that provide free remotely sensed data.
1.10 CHECK YOUR PROGRESS
1. Fill in the Blanks:
a) The technical term "remote sensing" was first used in the in the
__________ 1960 's.
b) __________is the process in which oncident energy retained by
particles in the atsmophere at a given wavelength.
c) ____________are the type of electromagnetic ra diation with
wavelength in the electromagnetic spectrum longer than infrared light.
d) Infrared was discovered in 1800 by astronomer ___________.
e) Wavelength is inversely proportional to_________of the wave.
2. Name the Following:
a. A device to detect the electro-magnetic radiation reflected or emitted
from an object
b. A measure used to describe the sharpness and clarity of an image or
picture
c. The first earth observation satellite that was launched in 1972
d. The resolution which is usually expressed in days.
e. A common example of a remotely sensed product.
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12 A B
a. Rayleigh scattering i. Medical industry
b. X rays ii. Aircraft
c. Aryabhatta iii. Sensor
d. Platform iv. Very small
particles
e. Camera v. First Indian
satellite 3. Match the Column:
1.11 ANSWERS TO THE QUESTIONS
1. Fill in the Blanks:
a. United States
b. Absorption
c. Radio waves
d. Sir W. Herschel e. Freque ncy
2. Name the Following:
a. Remote Sensor/ Sensor
b. Resolution
c. Since Landsat-1
d. Temporal
e. An aerial photograph
3. Match the Column:
a. Very small particles
b. Medical industry
c. First Indian satellite
d. Aircraft e. Sensor
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13 1.12 TECHN ICAL WORDS AND THEIR MEANINGS
Wavelength: the distance between successive crests of a wave,
especially points in a sound wave or electromagnet ic wave.
Spectrum: a band of colours, as seen in a rainbow, produced by
separation of the components of light by the ir different degrees
of refraction according to wavelength.
Radiation: the emission of energy as electromagnetic waves,
especially high-energy particles which cause ionization.
1.13 TASK
Visit Google Earth and observe the globe carefully. Try downloading
historical images for an area of your choice using the relevant tool.
Discuss the changes that have taken place and possible reasons for
the same.
6.13. REFERE NCES FOR FURTHER STUDY
Joseph, George (2005 ): ‘Fundame ntals of Remote Sensing’,
Universities Press, Hyderabad
Campbe ll, James (2011): ‘Introduction to Remote Sensing, Guildford
Press, New York
Kumar, S (2005 ): ‘Basics of Remote Sensing and GIS’, Laxm
Publications, New Delhi
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REMOTE SENSING – II
2.0. After going through this chapter you will be able to understand
the following:
Unit Structure :
2.1 Objectives
2.2 Introduction
2.3 Subject Discussion
2.4 Tasks of Image Interpretation: Classification, Delineation,
Measuremen t
2.5 Elements of Image Interpretation: Tone, Texture, Pattern, Size,
Shape, Shadow and Association
2.6 Visual Image Interpretation: Interpretation of at least four satellite
images employing image recognition elements
2.7 Thematic Mapping: Generation of thematic maps using trace paper
2.8 Summary
2.9 Check your progress
2.10 Answers to the questions
2.11 Technical words and their meanings
2.12 Task
2.13 References for further study
2.1 OBJECTIVES
To learn different tasks of image interpretation
To learn the elements of image interpretation
To understand the process of visual image interpretation
To learn the process of thematic mapping
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15 2.2 INTRODUCTION
Image interpretation is a powerful technique that helps us to identify and
distinguish various feature s in satellite imageries and aerial photographs.
Image interpretation involves identification of various features such as
forest cover, water bodies, urban settlement, agriculture, barren land, etc.
Identifying individual features from images and photograp hs is a key to
interpretation and information extraction.
2.3. SUBJECT DISCUSSION
Remote sensing is the art of extraction of information about an object or
phenomena without coming into physical contact with it. It is done
through satellites and air mount ed cameras. Therefore, there are two types
of remotely sensed data - satellite imageries and aerial photographs
respectively. Capturing images and photographs is the first step for
interpretation and extracting information about the area under study. This
chapter shall help us understand the keys of visual interpretation and
preparation of thematic maps from base maps.
2.4 TASKS OF IMAGE INTERPRETATION:
CLASSIFICATION, DELINEATION, MEASUREMENT
Image interpretation is not an art, but, a technique. If it is followed
systematically, the accuracy of image interpretation will improve. The task
of image interpretation can be classified into the following:
a. Classification : This task includes
identification of elements on the
images and classifying them into
various features with the help of a
table. It also includes enumeration of
features to keep a count of the same.
Same number or symbols may be
used to depict same features. For
example in the figure, numbers are used to indicate the same features.
No. 1 repre sents fields, no. 2 represents water body, no. 3 represents
settlements and no. 4 represents government land.
b. Delineation : This task includes
delineation of features that are
identified using similar numbers or
symbols. This is done using a
marker or co lour so that different
boundaries can be identified. It
helps in creating a new map
showing clearly delineated features
and land uses. The figure depicts
how features can be delineated using a pencil or a pen.
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16 c. Measurement : This task helps us to
measure th e distance between
features and area, perimeter, etc. of
the features. The scale of the image
helps to convert the distance
measured using a geometric scale
(in cms., mm., etc.) into distance on
the ground (in Kms., miles etc.).
The figure besides represen ts how
the distance between features can be measured on scale.
2.5 ELEMENTS OF IMAGE INTERPRETATION: TONE,
TEXTURE, PATTERN, SIZE, SHAPE, SHADOW AND
ASSOCIATION
a. Tone : Tone refers to the particular quality of brightness, deepness, or
hue of a shade of a co lour. Therefore tone refers to relative brightness
or colour of a feature on an image. The tonal variation makes it easier
to differentiate between various features on an image. Shapes, patterns
and textures on an image are identifiable mainly due tonal va riation.
b. Shape : Shape refers to the outline or structure of a particular feature.
The man made features are generally regular, symmetric or sharp in
shape while all natural features are irregular in shape. Most of the
features can solely be identified us ing the shape element of visual
interpretation.
c. Size: Comparing size of a feature in context with others in an image
helps in better understanding and interpretation of an image. A quick
estimate of size of a feature makes image interpretation process fast er
and convenient.
d. Pattern : Pattern refers to spatial arrangement of features. A repeated
sequence of certain form or relationships is characteristic of many
natural and constructed features which give an added advantage for
interpretation.
e. Texture : Textur e refers to frequency of tonal changes in a certain area
of an image. It is product of shape, size, tone, shadow and pattern of a
particular feature. It decides upon the visual roughness or smoothness
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17 of an image. Abrupt changes in grey scale results in Ro ugh texture
while very minor tonal variations are seen in smooth textures.
f. Shadow : Shadow refers to a dark area produced by the features
coming between light rays and surface. Shadows provide certain
relative height information of the feature and also an idea of the terrain
profile.
g. Association : Association is occurrence of certain feature in relation
with other. Certain features are not directly identifiable by its
appearance in an image but could be interpreted easily according to its
relationship with the surroundings. For example association of boats
with water, aircraft with runway, playground with school etc.
h. Colour key : The satellite imageries are of two types - False Colour
Composite (FCC) and True Colour Composite (TCC). The FCC
represents the feat ures in different colours from its actual colours
which make it to be called as false colours. The TCC represents all
features in the same colour as on the ground. However, FCC is more
reliable. The following table shows the common features’ colours
which may help you in interpreting the images:
Feature Colour in FCC Colour in TCC
Vegetation/Agriculture Red Green
Water bodies Black to Dark
Blue Blue
Settlements Grey Varies depending
upon the area
Transport lines Black Red/Grey
2.6 VISUAL IMAGE INTERPR ETATION
Just like how we visualize and try to understand our environment, visual
interpretation involves visualizing and understanding features in an image
or a photograph. It includes the meaning of the image content but also
goes beyond what can be seen on the image in order to recognize spatial
patterns. This process can be roughly divided into 2 levels:
The recognition of objects such as streets, fields, rivers, etc. The
quality of recognition depends on the expertise in image interpretation
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18
A true interpretation can be ascertained through conclusions (from
previously recognized objects) of situations, recovery, etc. Subject
specific knowledge and expertise are crucial.
Here is an example of visual image interpretation to help y ou understand
the process:
Interpretation : The above satellite imagery is of Greater Mumbai. It has
been captured from Landsat 8 in February 2014. The bands used represent
the image are 5, 4 and 3.
In the image, it can be observed that, there exists a lot of vegetation which
is represented in red colour. The red colour on the coasts represents
mangrove vegetation and the red patch in the eastern part represents
natural vegetation which is a part of Sanjay Gandhi National Park. An
airport can also be observ ed in the central part. Three lakes can be
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19 observed in the southern parts of Sanjay Gandhi National Park viz. Powai
lake, Tulsi lake and Vihar lake. There exists a huge water body around the
city which is Arabian Sea in the west and south and Thane creek i n the
east. In the north of the island exists Ulhas river. The city is highly urban
in nature, the settlements are therefore dense in nature. It is thus a
clustered pattern of settlement.
2.7 THEMATIC MAPPING: GEN ERATION OF
HEMATIC MAPS USING TRACE PAPER
To prepare a thematic map by tracing, a proper base map is essential first.
The following are the requirements in a base map:
Proper map scale to enable appropriate presentation of interpreted
information
Geographic coordinate system to establish the geo graphic reference
Basic map information to be printed in light tones as background
which results in enhancement of interpreted information.
Following are the types of base maps which can be used to create a
thematic map:
A topographic map with a scale of 1 :50,000, 1:100,000 or 1:250,000
is usually the preferable base map for higher resolution satellite image
interpretation.
Orthophoto maps are more easily used by cartographers for the
transfer of interpreted information, particularly in the case of forest
classification.
NATMO maps are best source of thematic information. They are
ready to use thematic maps with all the essential elements.
The procedure for tracing the thematic map is as follows:
Place a tracing paper on the base map. Mark the corners and f ix them
using a paper clip or a nail so that the paper doesn’t move while tracing.
Now start tracing the borders along with the information as per
requirement. Now transfer the traced information onto a paper where the
map will be finalized using a tracing table. With the light in the tracing
table, it will be easier to see through the paper and error minimization.
Represent information with the help of different colours and symbols.
2.8 SUMMARY
Remote sensing is the art of extraction of information about an object or
phenomena without coming into physical contact with it. Image
interpretation involves identification of various features such as forest
cover, water bodies, urban settlement, agriculture, barren land, etc.
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20 interpretation and information extraction. The elements of image
interpretation include shape, size, tone, texture, pattern, association and
shadow.
2.9 CHECK YOUR PROGRESS
1. Fill in the Blanks
a. ________ _is a powerful techni que that helps us to identify and
distinguish various features
b. ________ refers to spatial arrangement of features
c. Geographic coordinate system is used to establish the ________
d. __________ helps in creating a new map showing clearly delineated
features and land uses
e. A quick estimate of ___ ______ of a feature makes image interpretation
process faster and convenient.
2. Match the Columns
A B
a. Classification i. Distance between two features
b. Measurement ii. Location of features
c. Association iii. Identification of features
d. FCC iv. Demarcating features
e. Delineation v. Vegetation in Red colour
3. True of False
a. Tracing table helps to see through the paper for proper creation of
thematic maps
b. Transport lines are represented in red colour in FCC images
c. The man made features are generall y regular, symmetric or sharp in
shape
d. NATMO maps are best source of thematic information
e. The TCC represents all features in the different colour.
2.10 ANSWERS TO THE QUESTIONS
1. Fill in the blanks:
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21 c. Geographic reference
d. Delineati on
e. Size
2. Match the Columns:
a. iii
b. i
c. ii
d. v
e. iv
3. True or False:
a. True
b. False
c. True
d. True
e. False
2.11 TECHNICAL WORDS AND THEIR MEANINGS
Remote sensing: The scanning of the earth by satellite or high -flying
aircraft in order to obtain information about it.
Aerial p hotography: Aerial photography is the taking
of photographs of the ground from an elevated/direct -down position.
Usually the camera is not supported by a ground -based structure.
Satellite imagery: Satellite imagery is images of Earth or other
planets colle cted by imaging satellites operated by governments and
businesses around the world.
Thematic map: A thematic map is a map that emphasizes a particular
theme or special topic such as the average distribution of rainfall in an
area. They are different from g eneral reference maps because they do
not just show natural features like rivers, cities, political subdivisions
and highways.
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22
2.12 TASK
Interpret two satellite imageries - cultural and physical
Interpret any two aerial photographs
2.13 REFERENCES FO R FURTHER STUDY
Lille sand, Thomas; Kiefer Ralph and Chipman, Jonathan (2015):
‘Remote Sensing and Image Interpretation’, Wiley Publications, USA.
Bryson, Norman; Holly Michael and Moxey, Keith eds. (1994):
‘Visual Culture: Images and Interpretations’, Wes leyan University
Press, USA.
Sahu, Kali Charan (2008): ‘ Textbook of Remote Sensing and
Geographical Information Systems’, Atlantic Publishers and
Distributors, New Delhi
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23 3
GLOBAL POSITIONING SYSTEM (GPS)
3.0. After going through this chapter, you will be able to understand
the following:
Unit Structure :
3.1 Objectives
3.2 Introduction
3.3 Subject Discussion
3.4 Definition and Concept
3.5 Components: User Segment, Space Se gment and Control Segment
3.6 Types: Handheld GPS and DGPS
3.7 Applications: GPS Applications in Geography and General Use
3.8 Hands -on/ Practical: Demarcation of Point, Line and Polygon
features using GPS
3.9 Summary
3.10 Check your progress
3.11 Answers to the questions
3.12 Technical words and their meanings
3.13 Task
3.14 References for further study
3.1 OBJECTIVES
To understand the definition and concept of GPS
To understand the components and types of GPS
To learn the applications of GPS and undertak e hands -on practical
with GPS
3.2 INTRODUCTION
The Global Positioning System was conceived in 1960 under the
sponsorship of the U.S. Air Force, but in 1974 the other branches of the
U.S. military joined the effort. The first satellites were launched into s pace
in 1978. The System was declared fully operational in April 1995. The munotes.in
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24 Global Positioning System consists of 24 satellites, that circle the globe
once every 12 hours, to provide worldwide position, time and velocity
information. GPS makes it possible t o precisely identify locations on the
earth by measuring distance from the satellites. GPS allows you to record
or create locations from places on the earth and help you navigate to and
from those places. Originally the System was designed only for militar y
applications and it wasn’t until the 1980’s that it was made available for
civilian use also.
3.3 SUBJECT DISCUSSION
The Global Positioning System (GPS), originally Navstar GPS, is a space -
based radio navigation system owned by the United States governme nt
and operated by the United States Air Force. It is a global navigation
satellite system that provides geolocation and time information to a GPS
receiver anywhere on or near the Earth where there is an unobstructed line
of sight to four or more GPS satellites. The GPS system provides critical
positioning capabilities to military, civil, and commercial users around the
world. The United States government created the system, maintains it, and
makes it freely accessible to anyone with a GPS receiver. Advances in
technolog y and new demands on the existing system have now led to
efforts to modernize the GPS.
The Russian Global Navigation Satellite System ( GLONASS ) was
developed contemporaneously with GPS, but suffered from incomplete
coverage of the globe until the mid -2000s. GLONASS can be added to
GPS devices, making more satellites available and enabling positions to be
fixed more quickly and accurately, to within two meters. There are also
the European Uni on Galileo positioning system , China's BeiDou
Navigation Satellite System , India's NAVIC and Japan's Quasi -Zenith
Satellite System .
3.4 DEFINITION AND CONCEPT
Definition : GPS stands for "Global Positioning System." It may be
defined as ‘a satellite navigation system used to determine the ground
position of an object.’
Fig: 01: Trialteration of GPS
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25
Concept : GPS receivers take information transmitted from the
satellites and uses triangulation to calculate a user’s exact location.
The GPS constellation consists of two dozen GPS satellites in medium
Earth orbit. A GPS receiver can tell its own position by using the
position data of it, and compares that data with 3 or more GPS
satellites. To get the distance to each satellite, the GPS transmits a
signal to each satellite. The sig nal travels at a known speed. The
system measures the time delay between the signal transmission and
signal reception of the GPS signal. The signals carry information about
the satellite’s location. Determines the position of, and distance to, at
least thr ee satellites, to reduce error. The receiver computes position
using trilateration.
Functioning of GPS : The basis of the GPS is a constellation of
satellites that are continuously orbiting the earth. These satellites,
which are equipped with atomic clocks, transmit radio signals that
contain their exact location, time, and other information. The radio
signals from the satellites, which are monitored and corrected by
control stations, are picked up by the GPS receiver. A GPS receiver
needs only three satelli tes to plot a rough, 2D position, which will not
be very accurate. Ideally, four or more satellites are needed to plot a
3D position, which is much more accurate.
3.5 COMPONENTS OF GP
Fig: 02: Components/ Segments of GPS
Space Segment: The space segment consists of 29 satellites circling
the earth every 12 hours at 12,000 miles in altitude. This high altitude
allows the signals to cover a greater area. The satellites are arranged in
their orbits so a GPS receiver on earth can receive a signal from at
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26 least four satellites at any given time. Each satellite contains several
atomic clocks. The satellites transmit low radio signals with a unique
code on different frequencies, allowing the GPS receiver to identify
the signals. The main purpose of these coded s ignals is to allow the
GPS receiver to calculate travel time of the radio signal from the
satellite to the receiver. The travel time multiplied by the speed of light
equals the distance from the satellite to the GPS receiver.
Fig: 03: Satellite Constellation of GPS
Control Segment: The control segment tracks the satellites and then
provides them with corrected orbital and time information. The control
segment consists of five unmanned monitor stations and one Master
Control Station. The five unmanned stations monitor GPS satellite
signals and then send that information to the Master Control Station
where anomalies are corrected and sent back to the GPS satellites
through ground antennas.
Fig: 04: GPS Receive r
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27 User Segment: The user segment consists of the users and their GPS
receivers. The number of simultaneous users is limitless. The user
receivers can be hand -held or, can be placed in a vehicle. All GPS
receivers have a calendar programmed into their comp uter, which tells
them where each satellite is at any given moment.
3.6 TYPES OF GPS: MAN HELD GPS AND DGPS
GPS: A global positioning system (GPS) is a navigation system that
consists of one or more earth -based receivers that accept and analyze
signals sen t by satellites in order to determine the receiver’s geographic
location. A GPS receiver is a handheld, mountable, or embedded device
that contains an antenna, a radio receiver, and a processor. Many include a
screen display that shows an individual’s loca tion on a map. Some also
function as a portable media player. Many mobile devices such as smart
phones have GPS capability built into the device or as an add -on feature.
Some users carry a handheld GPS receiver; others mount a receiver to an
object such as an automobile, boat, airplane, farm and construction
equipment, or computer.
DGPS: DGPS stands for Differential Global Positioning System, is
an enhancement in GPS that is created to provide more location accuracy.
Satellites in the space provide signals to the earth’s surface at the speed of
light, but through any atmospheric change there can be an error. And due
to this error, a delay can be caused, and for all these errors, DGPS is
created and it adjusts these errors to provide accurate location. Fixed,
ground based reference stations are used in the DGPS systems, that
broadcasts the difference between positions GPS satellite systems and
known fixed positions. DGPS refers to a general technique of
Augmentation.
Fig: 05: Functioning of DGPS
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28 3.7 APPLICA TIONS: GPS APPLICATIONS IN
GEOGRAPHY AND GENERAL USE
GPS isn’t just used by civilians; it’s also used by pilots, boat captains,
farmers, surveyors, scientists and the military too. Following are some of
the applications of GPS:
Aviation : Almost all modern aircraft are fitted with multiple GPS
receivers. This provides pilots (and sometimes passengers) with a real -
time aircraft position and map of each flight’s progress. GPS also
allows airline operators to pre -select the safest, fastest and most fuel -
efficie nt routes to each destination, and ensure that each route is
followed as closely as possible when the flight is underway.
Marine : When high accuracy GPS is fitted to boats and ships, it
allows captains to navigate through unfamiliar harbours, shipping
chan nels and waterways without running aground or hitting known
obstacles. GPS is also used to position and map dredging operations in
rivers, wharfs and sandbars, so other boats know precisely where it is
deep enough for them to operate.
Farming : Farmers rely on repeat planting season after season to
maximize their crop productions. By putting GPS receivers on tractors
and other agricultural equipment, farmers can map their plantations
and ensure that they return to exactly the same areas when sewing their
seeds in future. This strategy also allows farmers to continue working
in low visibility conditions such as fog and darkness, as each piece of
machinery is guided by its GPS position instead of visual references.
High accuracy GPS is also used to map soil sam ple locations, allowing
farmers to see where the soil is most fertile across individual fields or
even entire farms.
Science: Scientists use GPS technology to conduct a wide range of
experiments and research, ranging from biology to physics to earth
scienc es. Traditionally, when scientists wanted to understand where
and how far animals roam, they had to tag animals with metal or
plastic bands and then follow them to various locations to monitor
their movement. Today, scientists can fit animals with GPS coll ars or
tags that automatically log the animal’s movement and transmit the
information via satellite back to the researchers. This provides them
with more detailed information about the animal’s movements without
having to relocate specific animals. Earth s cientists also use GPS
technology to conduct a wide range of research. By installing high
accuracy GPS receivers on physical features such as glaciers or
landslips, scientists can observe and study both the speed and direction
of movement, helping them to understand how landscapes change over
time. Similarly, GPS receivers can be installed on solid bedrock to
help understand very small and very slow changes in tectonic plate
motion across the world.
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29 Surveying: Surveyors are responsible for mapping and mea suring
features on the earth’s surface and under water with high accuracy.
This includes things like determining land boundaries, monitoring
changes in the shape of structures or mapping the sea floor. Surveyors
have historically required line -of-sight bet ween their instruments in
order to undertake such work, but the availability of high accuracy
GPS receivers has reduced the need for this. GPS can either be setup
over a single point to establish a reference marker, or it can be used in
a moving configurat ion to map out the boundaries of various features.
This data can then be transferred into mapping software to create very
quick and detailed maps for customers.
Military: The GPS system was originally developed by the United
States Department of Defence f or use by the US military, but was later
made available for public use. Since then, GPS navigation has been
adopted by many different military forces around the world, including
the Australian Defence Force. Some countries have even decided to
develop thei r own satellite navigation networks for use during
wartimes. Today, GPS is used to map the location of vehicles and
other assets on various battlefields in real time, which helps to manage
resources and protect soldiers on the ground. GPS technology is als o
fitted to military vehicles and other hardware such as missiles,
providing them with tracking and guidance to various targets at all
times of the day and in all weather conditions
3.8 HANDS -ON/ PRACTICAL: DEMARCATION OF
POINT, LINE AND POLYGON FEATURES U SING GPS
Using a GPS, a survey can be conducted. Location of point features like
trees, wells, street lights, etc. can be recorded. Similarly, a linear feature
like a pathway, road, a route, railway line, river etc. can be selected. The
locations of starti ng point and ending point can be recorded. Also, several
locations on the circumference of an aerial feature like a garden, a
playground, parking area of a mall, etc. can be recorded. After the survey
is over, we can connect the GPS to a computer having th e required
software and transfer the locational information to demarcate the point,
line and polygon features or a mental map can be drawn to plot the
locational information at the points surveyed. Use of appropriate
cartographic symbols is highly essentia l.
3.9 SUMMARY
The Global Positioning System (GPS), originally Navstar GPS, is a space -
based radio navigation system owned by the United States government
and operated by the United States Air Force. GPS stands for "Global
Positioning System." It may be d efined as ‘a satellite navigation system
used to determine the ground position of an object.’ GPS receivers take
information transmitted from the satellites and uses triangulation to
calculate a user’s exact location. It consists of three components viz. s pace
segment , control segment and user segment. DGPS stands for Differential munotes.in
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30 Global Positioning System, is an enhancement in GPS that is created to
provide more location accuracy
GPS isn’t just used by civilians; it’s also used by pilots, boat captains,
farmers, surveyors, scientists and the military too. Using a GPS, a survey
can be conducted. Location of point features like trees, wells, street lights,
etc. can be recorded.
3.10 CHECK YOUR PROGRESS
1. Fill in the Blanks:
a. The Global Positioning System (GPS) i s originally ________ GPS.
b. The basis of the GPS is a ___________that are continuously orbiting
the earth.
c. Use of appropriate ____________symbols is highly essential in map
making.
d. DGPS refers to a general technique of _________________.
e. The GPS constellati on consists of two dozen GPS satellites in
_________Earth orbit.
2. Name the Following:
a. The segment controlling the satellite constellation.
b. GPS used to calculate difference in the location value
c. Method of calculating location used by GPS
3. Match the Column:
A B
a. Trees i. Polygon feature
b. Mobile GPS ii. Line feature
c. Food Court in a mall iii. Error correction
d. DGPS iv. Point feature
e. 100 mts. race track v. User Segment
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31 3.11 ANSWERS TO THE QUESTIONS
1. Fill in the Blanks:
a. Navstar
b. Constellation of satellites
c. Cartographic
d. Augme ntation
e. Medium
2. Name the Following:
a. Control segment
b. DGPS
c. Trialteration method
3. Match the Column:
a. Point feature
b. User Segment
c. Polygon feature
d. Error correction
e. Line feature
3.12 TECHNICAL WORDS AND THEIR MEANINGS
Satellite : An artificial body placed in orbit round the earth or another
planet in order to collect information or for communication.
Navigation : The process or activity of accurately ascertaining one's
position and planning and following a route.
Constellation : A satellite constellation is a group of artificial satellites
working in concert.
Point, line and polygon features : Features used to represent real
elements on computer in the form of vector data.
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32 3.13 TASK
Using GPS in your smart phone or in car try to record locational
information for diffe rent areas and plot them on a mental map.
3.14 REFERENCES FOR FURTHER STUDY
El-Rabbany , Ahmed (2002): ‘Introduction to GPS: The Global
Positioning System’, Artech House, London.
Xu, Guochang (2007): ‘GPS : Theory, Algorithms and Applications’,
Springer, N ew York.
Brawn, David (2003): ‘GPS: The Easy Way’, Discovery Walking
Guides Limited, England.
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33 4
GEOGRAPHICAL INFORMATION
SYSTEM - I
4.0. After going through this chapter you will be able to understand
the following:
Unit Structure :
4.1 Objectives
4.2 Introduction
4.3 Subject Discussion
4.4 Definition, Concept and Components of GIS
4.5 Summary
4.6 Check your progress
4.7 Answers to the questions
4.8 Technical words and their meanings
4.9 Task
4.10 References for further study
4.1 OBJECTIVES
To understand the concept and components of GIS
To understand the applications of GIS
To undertake hands -on/ practical using available or free software - Q
GIS
4.2 INTRODUCTION
A geographic information system (GIS) is a computer system for
capturing, storing, checking, and displaying data related to positions on
Earth’s surface. GIS can help individuals and orga nizations better
understand spatial patterns and relationships. It is a crucial part of spatial
data infrastructure. GIS can use any information that includes location.
Many different types of information can be compared and contrasted using
GIS. With GIS technology, people can compare the locations of different
things in order to discover how they relate to each other. For example,
using GIS, a single map could include sites that produce pollution, such as munotes.in
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34
factories, and sites that are sensitive to polluti on, such as wetlands and
rivers. Such a map would help people determine where water supplies are
most at risk.
4.3 SUBJECT DISCUSSION
Technology has always been a companion to man and has helped in his
development. GIS is one of the advanced technologies t hat has enabled
man to understand changes that have taken place in the past, analyse space
at one place and predict future of the same. The technology is computer
based and is easy to grasp, but, requires expertise so that predictions and
outcomes can be a ccurate. The technology has a geographical base, but,
relates to every possible field and is still progressive.
3.4 DEFINITION, CONCEPT AND COMPONENTS
Definition : A geographic information system (GIS) is a system
designed to capture, store, manipulate, ana lyse, manage, and present
spatial or geographic data.
Concept: GIS is majorly a mapping technology. It may be carried out
manually and digitally. It is heavily dependent on spatial and attribute
data. It allows the data to be created and stored in the for m of
geometrical features in different layers. Each layer has its own identity
and ability to be edited. All layers together make the entire map or the
dataset. It enables various spatial, query and geometrical analysis.
There are several commercial and op en source softwares like ArcGIS
and QGIS respectively. GIS basically helps in analysing land without
visiting it much.
Components: The components of GIS are as follows:
1. Software : GIS software
provides the functions and tools
needed to store, analyse, and
display geographic information.
Key software components are (a) a
database management system
(DBMS) (b) tools for the input and
manipulation of geographic
information (c) tools that support
geographic query, analysis, and
visualization (d) a graphical user
interface (GUI) for easy access to
tools. GIS softwares are either commercial software or software developed
on Open Source domain, which are available for free.
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35 2. Hardware : Hardware is the computer on which a GIS operates.
Today, GIS runs on a wide range of hardware types, from centralized
computer servers to desktop computers used in stand -alone or networked
configurations.
3. Data : The most important component of a GIS is the data.
Geographic data or spatial data and related tabular data can be coll ected
in-house or bought from a commercial data provider. Spatial data can be
in the form of a map/remotely -sensed data such as satellite imagery and
aerial photography. These data forms must be properly georeferenced
(latitude/longitude). Tabular data can be in the form attribute data that is in
some way related to spatial data.
4. Users: GIS technology is of limited value without the users who
manage the system and to develop plans for applying it. GIS users range
from technical specialists who design and m aintain the system to those
who use it to help them do their everyday work. The user -friendly
interface of the GIS software allows the nontechnical users to have easy
access to GIS analytical capabilities without needing to know detailed
software commands.
4.5 APPLICATIONS OF GIS IN GEOGRAPHY AND
RELATED FIELDS
1. GIS in Mapping : Mapping is a central function of Geographic
Information System, which provides a visual interpretation of data. People
from different professions use map to communicate. It is no t necessary to
be a skilled cartographer to create maps.
2. Telecom and Network services : GIS can be a great planning and
decision making tool for telecom industries. This technology allows
telecom to enhance a variety of application like engineering applicat ion,
customer relationship management and location based services.
3. Accident Analysis and Hot Spot Analysis : GIS can be used as a
key tool to minimize accident hazard on roads, the existing road network
has to be optimized and also the road safety measu res have to be
improved. This can be achieved by proper traffic management. By
identifying the accident locations, remedial measures can be planned by
the district administrations to minimize the accidents in different parts of
the world.
4. Urban Planning : GIS technology is used to analyse the urban
growth and its direction of expansion, and to find suitable sites for further
urban development.
5. Transportation Planning : GIS can be used in managing
transportation and logistical problems. GIS can also help in m onitoring
rail systems and road conditions.
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36 6. Environmental Impact Analysis : EIA is an important policy
initiative to conserve natural resources and environment. The EIA can be
carried out efficiently by the help of GIS. By integrating various GIS
layers, a ssessment of natural features can be performed.
7. Agricultural Applications : GIS can be used to create more
effective and efficient farming techniques. It is fully integrated and widely
accepted for helping government agencies to manage programs that
support farmers and protect the environment. This could increase food
production in different parts of the world so the world food crisis could be
avoided.
8. Disaster Management and Mitigation : Today well -developed GIS
systems are used to protect the environment. I t has become an integrated,
well developed and successful tool in disaster management and mitigation.
GIS can help with risk management and analysis by displaying which
areas are likely to be prone to natural or man -made disasters. When such
disasters are identified, preventive measures can be developed.
9. Determine land use/land cover changes : Land cover means the
feature that is covering the barren surface .Land use means the area in the
surface utilized for particular use. The role of GIS technology in lan d use
and land cover applications is that we can determine land use/land cover
changes in the different areas. Also it can detect and estimate the changes
in the land use/ land cover pattern within time. It enables to find out
sudden changes in land use an d land cover either by natural forces or by
other activities like deforestation.
10. Navigation (routing and scheduling) : Web -based navigation maps
encourage safe navigation in waterway. This division is providing public
information that makes citizens awarene ss of these vessel locations
through web map. The web map will be regularly updated to keep the
boating public informed of these coastal hazards to minimize risk of
collision and injury.
4.6 HANDS -ON/ PRACTICAL USING AVAILABLE OR
FREES SOFTWARE - Q GIS QUAN TUM
GEOGRAPHICAL INFORMATION SYSTEM
(QGIS):
QGIS stands for Quantum GIS. It is a cross -platform free and open -
source desktop geographic information system (GIS) application that
supports viewing, editing, and analysis of geospatial data. QGIS functi ons
as geographic information system (GIS) software, allowing users to
analyse and edit spatial information, in addition to composing and
exportin g graphical maps. QGIS supports both raster and vector layers;
vector data is stored as eith er point, line, or polygon features. Multiple
formats of raster images are supported and the software can geo-
reference images.
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37 Geo-referencing: Geo-referencing means to associate something with
locations in physical space. The term is commonly used in the
geographic information systems field to describe the process of
associating a physical map or raster image of a map with spatial
locations.
Georeferencing may be applied to any kind of object or structure that can
be related to a geographical location , such as points of interest , roads,
places, bridges, or buildings Geographic locations are most commonly
represented using a coordinate reference system , which in turn can be
related to a geodetic reference system such as WGS -84.
Digitization: Digitizing in GIS is the process of converting geographic
data either from a hardcopy or a scanned image into vector data by
tracing the features. During the digitizing process, features from the
traced map or image are c aptured as coordinates in either point, line, or
polygon format.
1. Point layer: Points are the zero -dimensional objects that contain
only a single coordinate pair. Points are typically used to model singular,
discrete features such as buildings, wells, pow er poles, sample locations,
and so forth. Points have only property of locations. Other types of point
feature include the node and the vertex. Points can be spatially linked to
form more complex features.
2. Line layer: Lines are one dimensional features com posed of
multiple, explicitly connected points. Lines are used to represent linear
features such as roads, streams, faults, boundaries, and so forth. Lines
have a property of length. Lines that directly connect nodes are sometimes
referred to as chains, ed ges, segments or arcs.
3. Polygon layer: Polygons are two -dimensional features created by
multiple lines that loop back to create a “closed” feature. In the case of
polygons, the first coordinate pair on the first line segment is the same as
the last coordin ate pair on the last line segment. Polygons are used to
represent features such as city boundaries, geologic formations, lakes, soil
associations, vegetation communities and so forth. Polygons have the
properties of area and perimeter. Polygons are also ca lled areas.
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38 4.7 SUMMARY
A geographic information system (GIS) is a computer system for
capturing, storing, checking, and displaying data related to positions on
Earth’s surface. The components of GIS are hardware, software, user and
data. Applications o f GIS include mapping, disaster management and
mitigation, hazard reduction, soil analysis, agricultural analysis,
transportation analysis and a lot more. QGIS is one of the free and open
source softwares of GIS. It helps in performing a lot of spatial and aspatial
analysis. The three main features of GIS are point, line and polygon.
4.8 CHECK YOUR PROGRESS
1. Fill in the Blanks:
a. GIS is majorly a ________ technology .
b. GIS can help with risk management and analysis by displaying
which areas are likely to be pro ne to ___________.
c. ________ can be spatially linked to form more complex features .
d. ____ is an important policy initiative to conserve natural resources
and environment
e. GIS technology is of limited value without the ________ who
manage the system
2. Name the Following:
a. Set of information
b. Open source (free) GIS software
c. Human component of GIS
d. Zero dimensional features
e. Multi -dimensional features
3. Match the Column:
A B
a. Point Imagery
b. Line Aerial photograph
c. Polygon Tube wells
d. Satellite Pond
e. Air mounted Camera River
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39 4.9 ANSWERS TO THE QUESTIONS
1. Fill in the Blanks:
a. Mapping
b. Natural or man -made disasters
c. Points
d. EIA
e. Users
2. Name the Following:
a. Data
b. QGIS
c. User/ Liveware
d. Point
e. Polygon
3. Match the Column:
a. Tube wells
b. River
c. Pond
d. Imagery
e. Aerial photograph
4.10 TECHNI CAL WORDS AND THEIR MEANINGS
Data : Set of information is called data. Here, it can be of two types
viz. spatial data (related to space) and attribute or apsatial data
(related non -spatial information).
Remote Sensing : The art of capturing information about an object or
phenomena without coming into physical contact with it. It can be
captured either through satellites or air mounted cameras.
Geo-referencing: The procedure of assigning coordinates to spatial
data.
Digitization : It is the process of digital ly tracing spatial data to
create maps. munotes.in
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40 4.11 TASK
Visit the GIS department of MCGM and study their mapping procedure to
understand the concept better. Try to enlist the problems faced by the
experts and solutions they apply to overcome them.
4.12 REFERENCE S FOR FURTHER STUDY
Bernhardsen, Tor (2002): ‘ Geographic Information Systems: An
Introduction ’, John Wiley and Sons, New York
Longley, Paul et. al. (2011): Geographic Information Systems and
Science, John Wiley and Sons, New York
www.mapsofindia.com
munotes.in
Page 41
41 5
GEOGRAPHICAL INFORMATION
SYSTEM - II
4.0. After going through this chapter you will be able to understand
the following:
Unit Structure :
4.1 Objectives
4.2 Introduction
4.3 Subject Discussion
4.5 Applications of GIS
4.6 Hands -on/ practical using availab le or free software - Q GIS
4.7 Summary
4.8 Check your progress
4.9 Answers to the questions
4.10 Technical words and their meanings
4.11 Task
4.12 References for further study
4.1 OBJECTIVES
To understand the applications of GIS
To undertake hands -on/ p ractical using aan vailable or free software -
Q GIS
4.2 INTRODUCTION
A geographic information system (GIS) is a computer system for
capturing, storing, checking, and displaying data related to positions on
Earth’s surface. GIS can help individuals and org anizations better
understand spatial patterns and relationships. It is a crucial part of spatial
data infrastructure. GIS can use any information that includes location.
Many different types of information can be compared and contrasted using
GIS. With GIS technology, people can compare the locations of different
things in order to discover how they relate to each other. For example,
using GIS, a single map could include sites that produce pollution, such as
factories, and sites that are sensitive to pollut ion, such as wetlands and munotes.in
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42 rivers. Such a map would help people determine where water supplies are
most at risk.
4.3 SUBJECT DISCUSSION
Technology has always been a companion to man and has helped in his
development. GIS is one of the advanced technologies that has enabled
man to understand changes that have taken place in the past, analyse space
at one place and predict future of the same. The technology is computer
based and is easy to grasp, but, requires expertise so that predictions and
outcomes can be accurate. The technology has a geographical base, but,
relates to every possible field and is still progressive.
4.4 APPLICATIONS OF GIS IN GEOGRAPHY AND
RELATED FIELDS
1. GIS in Mapping : Mapping is a central function of Geographic
Information System, whi ch provides a visual interpretation of data. People
from different professions use map to communicate. It is not necessary to
be a skilled cartographer to create maps.
2. Telecom and Network services : GIS can be a great planning and
decision making tool for t elecom industries. This technology allows
telecom to enhance a variety of application like engineering application,
customer relationship management and location based services.
3. Accident Analysis and Hot Spot Analysis : GIS can be used as a
key tool to minimize accident hazard on roads, the existing road network
has to be optimized and also the road safety measures have to be
improved. This can be achieved by proper traffic management. By
identifying the accident locations, remedial measures can be plann ed by
the district administrations to minimize the accidents in different parts of
the world.
4. Urban Planning : GIS technology is used to analyse the urban
growth and its direction of expansion, and to find suitable sites for further
urban development.
5. Tran sportation Planning : GIS can be used in managing
transportation and logistical problems. GIS can also help in monitoring
rail systems and road conditions.
6. Environmental Impact Analysis : EIA is an important policy
initiative to conserve natural resources a nd environment. The EIA can be
carried out efficiently by the help of GIS. By integrating various GIS
layers, assessment of natural features can be performed.
7. Agricultural Applications : GIS can be used to create more
effective and efficient farming techniq ues. It is fully integrated and widely
accepted for helping government agencies to manage programs that
support farmers and protect the environment. This could increase food munotes.in
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43 production in different parts of the world so the world food crisis could be
avoid ed.
8. Disaster Management and Mitigation : Today well -developed GIS
systems are used to protect the environment. It has become an integrated,
well developed and successful tool in disaster management and mitigation.
GIS can help with risk management and analy sis by displaying which
areas are likely to be prone to natural or man -made disasters. When such
disasters are identified, preventive measures can be developed.
9. Determine land use/land cover changes : Land cover means the
feature that is covering the barren surface .Land use means the area in the
surface utilized for particular use. The role of GIS technology in land use
and land cover applications is that we can determine land use/land cover
changes in the different areas. Also it can detect and estimate th e changes
in the land use/ land cover pattern within time. It enables to find out
sudden changes in land use and land cover either by natural forces or by
other activities like deforestation.
10. Navigation (routing and scheduling) : Web -based navigation maps
encourage safe navigation in waterway. This division is providing public
information that makes citizens awareness of these vessel locations
through web map. The web map will be regularly updated to keep the
boating public informed of these coastal hazards to minimize risk of
collision and injury.
4.6 HANDS -ON/ PRACTICAL USI NG AVAILABLE OR
FREES SOFTWARE - Q GIS QUANTUM
GEOGRAPHICAL INFORMATION SYSTEM
(QGIS):
QGIS stands for Quantum GIS. It is a cross -platform free and open -
source desktop geographic inf ormation system (GIS) application that
supports viewing, editing, and analysis of geospatial data. QGIS functions
as geographic information system (GIS) software, allowing users to
analyse and edit spatial information, in addition to composing and
exporting graphical maps. QGIS supports both raster and vector layers;
vector data is stored as either point, line, or polygon features. Mu ltiple
formats of raster images are supported and the software can geo-
reference images.
Geo-referencing: Geo-referencing means to associate something with
locations in physic al space. The term is commonly used in the
geographic information systems field to describe the process of
associating a physical map or raster image of a map with spatial
locations.
Georeferencing may be applied to any kind of object or structure that can
be related to a geographical location , such as points of interest , roads,
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44 represented using a coordinate reference system , which in turn can be
related to a geodet ic reference system such as WGS -84.
Digitization: Digitizing in GIS is the process of converting geographic
data either from a hardcopy or a scanned image into vector data by
tracing the features. During the digitizing process, features from the
traced map or image are captured as coordinates in either point, line, or
polygon format.
1. Point layer: Points are the zero -dimensional objects that contain
only a singl e coordinate pair. Points are typically used to model singular,
discrete features such as buildings, wells, power poles, sample locations,
and so forth. Points have only property of locations. Other types of point
feature include the node and the vertex. P oints can be spatially linked to
form more complex features.
2. Line layer: Lines are one dimensional features composed of
multiple, explicitly connected points. Lines are used to represent linear
features such as roads, streams, faults, boundaries, and so fo rth. Lines
have a property of length. Lines that directly connect nodes are sometimes
referred to as chains, edges, segments or arcs.
3. Polygon layer: Polygons are two -dimensional features created by
multiple lines that loop back to create a “closed” featur e. In the case of
polygons, the first coordinate pair on the first line segment is the same as
the last coordinate pair on the last line segment. Polygons are used to
represent features such as city boundaries, geologic formations, lakes, soil
associations , vegetation communities and so forth. Polygons have the
properties of area and perimeter. Polygons are also called areas.
4.7 SUMMARY
A geographic information system (GIS) is a computer system for
capturing, storing, checking, and displaying data related to positions on
Earth’s surface. The components of GIS are hardware, software, user and
data. Applications of GIS include mapping, disaster management and
mitigation, hazard reduction, soil analysis, agricultural analysis,
transportation analysis and a lo t more. QGIS is one of the free and open
source softwares of GIS. It helps in performing a lot of spatial and aspatial
analysis. The three main features of GIS are point, line and polygon.
munotes.in
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Geographical Information
System - Ii
45 4.8 CHECK YOUR PROGRESS
1. Fill in the Blanks:
a) GIS is majorly a ________ __ technology .
b) GIS can help with risk management and analysis by displaying which
areas are likely to be prone to ___________ .
c) ____________ can be spatially linked to form more complex features
d) ____ is an important policy initiative to conserve natural res ources and
environment
e) GIS technology is of limited value without the ________ who manage
the system
2. Name the Following:
a. Set of information
b. Open source (free) GIS software
c. Human component of GIS
d. Zero dimensional features
e. Multi -dimensional features
3. Match th e Column:
A B
a. Point Imagery
b. Line Aerial photograph
c. Polygon Tube wells
d. Satellite Pond
e. Air mounted Camera River
4.9 ANSWERS TO THE QUESTIONS
1. Fill in the Blanks:
a. Mapping
b. Natural or man -made disasters
c. Points
d. EIA
e. Users
munotes.in
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46 2. Name the Following:
a. Data
b. QGIS
c. User/ Liveware
d. Point
e. Polygon
3. Match the Column:
a. Tube wells
b. River
c. Pond
d. Imagery
e. Aerial photograph
4.10 TECHNICAL WORDS AND THEIR MEANINGS
Data : Set of information is called data. Here, it can be of two types
viz. spatial data (related to space) and attri bute or apsatial data (related
non-spatial information).
Remote Sensing : The art of capturing information about an object or
phenomena without coming into physical contact with it. It can be
captured either through satellites or air mounted cameras.
Geo-referencing: The procedure of assigning coordinates to spatial
data.
Digitization : It is the process of digitally tracing spatial data to create
maps.
4.11 TASK
Visit the GIS department of MCGM and study their mapping procedure to
understand the concept be tter. Try to enlist the problems faced by the
experts and solutions they apply to overcome them.
4.12 REFERENCES FOR FURTHER STUDY
Bernhardsen, Tor (2002): ‘ Geographic Information Systems: An
Introduction ’, John Wiley and Sons, New York
Longley, Paul et. a l. (2011): Geographic Information Systems and
Science, John Wiley and Sons, New York
www.mapsofindia.com
munotes.in