REMOTE SENSING
Remote sensing and GIS:
Reference books
1.Lillesand T.M and R.W. Kiefer, “Remote Sensing and Image
Interpretation” John Wiley & sons Inc.NY , 2000.4th edn.
2.C.P. Lo and Albert K.W.Yeung,“Concepts and Techniques of
Geographic Information Systems”, Prentice-Hall of India Private
Ltd. 2005. ISBN-81-203—2230-4
3.Bhatta .B ,“ Remote Sensing and GIS” Oxford university press.
2009.
4.Agarwal .C .S and Garg P.K,“ Text book on Remote sensing”
Wheeler Publishing , 2000
5.George Joseph, Fundamentals of Remote Sensing’, University
press(India ) Pvt.Ltd., 2003.
6.Sabins, Floyd F., 2001, Remote Sensing: Principals and
Interpretation: W. H. Freeman and Company, New York,
REMOTE SENSING
Definition: “Remote sensing is the science and art of obtaining
information about an object, area or phenomenon through the
analysis by a device that is not in contact with the object ,area
or phenomenon under investigation”
Remote Sensing: terms
Electromagnetic Radiation (EMR) :
The energy transported by the propagation of sun light. Measurement of
EMR is generally the basis of remote sensing.
Reflectance:
A measurement of ability of a surface to refelect energy. Ratio of radiant
energy v/s incident energy
Brightness values or digital values:
The remote sensing system record the amount of reflected or emitted
energy from the earth surface as digital values on the magnetic media
for digital image processing.
Spectral band:
A range of wavelength in the electromagnetic spectram a series of
intensity values measured and stored with in the selected wave length
interval “λ”
Panchromatic:
Remote Sensing: terms
Multispectral:
Two or more spectral band
Spectral signature :
Quantitative measurement of the properties of an object at one
or several wave lengths.
Spatial resolution:
The smallest object of the ground that can be seen on the image.
Multi- emporal:
Two or more images that have been recorded over the same
area but at different times /dates
Sensor:
A device that receives electromagnetic radiation, converts it
into a signal and presents it in a form suitable for obtaining
information on an object
Remote Sensing: terms
Pixel:
A picture element having both spatial and spectral aspects
Scene:
The area on the ground that is covered by an image
Image:
The presentation of a scene by optical, electro-optical, opto-mechanical or
electronic means
Colour composite:
A colour image which is produced by assigning three primary colours one each
to different wave lengths of a scene.
False colour composite (FCC):
A colour image produced by red,green and blue wavelengths ,so that the
colours produced by earth’s surface do not correspond to normal visual
experience.
(Example- very near infra red as red, red as green and green as blue)
Remote Sensing: terms
Class:
A surface characteristic type such as forest or water that is of
interest to the investigator
Thematic map:
A map designated to illustrate a particular class or theme
Ground truth:
The data gathered from field visits or existing records and
used to assists in interpreting imagery
Land use and land cover:
The surface of land used in various ways like agriculture, urban
etc….
The surface cover of the earth like water, forest …
Types of remote sensing data
Types of remote sensing data
Aerial remote
sensing data
Satellite remote
sensing data
Platform – aircraft
Data:
Black and White
Colour photos
Platform – satellite
Data:
Black and White
FCC
CCTs and CDs
Remote sensing platforms and sensor
systems
Platform play a vital role in remote sensing data
acquisition .
PLATFORM
AIRBORNE
SPACE BORNE
Airborne
Balloons: used in specific projects- restricted by metro factors
like wind velocity and direction
Aircraft: flexibility of flying altitude, data acquisition,
maximum stability, free from vibration uniform speed…
aircraft used
Aircraft
Dakota
Min. speed
240 km/hr
Height (m)
6000-7000
Avro
600 km/hr
8000
Canberra
Cessna
560 km/hr
350 km/hr
5000
9000
Space borne
Satellites: metrological mapping , natural resources,
communication….
What is a satellite?
Satellites are objects that travel in a definite path
around a parent planet.
Natural satellites
Artificial satellites
Geo stationary satellites
Sun-synchronous satellites
Geo stationary satellites
A geosynchronous satellite is a satellite in
geosynchronous orbit, with an orbital period the
same as the Earth's rotation period.
Such a satellite returns to the same position in the
sky after each sidereal day.
A special case of geosynchronous satellite is the
geostationary satellite, which has a geostationary
orbit – a circular geosynchronous orbit directly
above the Earth's equator
• Example: INSAT 1A,1B….
near-polar orbits
geostationary orbits
Sun-synchronous
A Sun-synchronous orbit is a geocentric orbit which
combines altitude and inclination in such a way
that an object on that orbit ascends or descends
over any given Earth latitude at the same local
mean solar time.
The surface illumination angle will be nearly the
same every time. This consistent lighting is a
useful characteristic for satellites that image the
Earth's surface in visible or infrared wavelengths
(example: IRS series- weather and spy satellites)
year
1975
1979
1980
1981
1983
1988
1991
1994
1995
1996
Land mark
Aryabhatta sattlite
Bhaskara
SLV-3 and Rohini
satellite
APPLE (Ariane Passenger
Pay Load Experiment)
Salient features
Launched by Soviet Union Wt.360 kg
Launched by USSR wt 440 kg
SLV 3 first Indian satellite launching vehicle
Launched by Europe Ariane rocket into
geostationary orbit
Carried solid state smart camera
Rohini satellite
Launched by Khazakistan
IRS – 1A
Similar to IRS 1A
IRS -1B
PSLV (Polar Satellite Launch
Vehicle) – carrying IRS P2 IRS –P2 launched from Sriharikota
Launched from Khazakistan
IRS -1C
PSLV –D3
From Sriharikota
IRS P3
IRS-P3
IRS-P2 failed
IRS-1D
IRS-P4 (OCEANSAT-1)
IRS-P5 (CARTOSAT-1)
IRS-2A
IRS-P6
(RESOURCESAT-1)
IRS-2B
1996LISS-3
LISS 2
LISS-3
early
1998
Multi-frequency
Scanning
Microwave
Radiometer
(MSMR)
1998LISS-4
2000LISS-4
LISS-4 and
end 2000 improved 3
2004LISS-4
GSAT -7
•
•
India's first exclusive satellite for Navy, GSAT-7, was successfully launched by
European space consortium Arianespace's Ariane 5 rocket from Kourou spaceport
in French Guiana.
GSAT-7 is India's first dedicated spacecraft for defense applications. GSAT-7 has a
lift-off mass of 2625 kg and is based on ISRO's 2500 kg satellite bus with some new
technological elements, including the antennae. Its solar arrays generate 2900 W
of electrical power.
Sensor
What is a sensor?
A device which can perceive the information
through the reflected/emitted light from
various objects.
Examples: human eye, Camera
TYPES OF SENSORS
ACTIVE SENSOR
Sends a beam of light
energy onto the orbit and
detects the reflected light
energy.
- RADAR (Radio Detection
and Ranging)
PASSIVE SENSOR
Passive sensor is the one
which detects the emitted
or reflected EMR from sun
light.
Sensor take the pictures
with the help of emitted/
reflected light energy
SWATH
Remote sensing
What is remote sensing?
“ the science and art of acquiring information
about objects from measurements made from
a distance without any physical contacts with
the object”
ELECTROMAGNETIC RADIATION
Remote sensing employs the detection of
electromagnetic radiation and its interaction
with earth materials.
Electromagnetic radiation is simply energy
traveling in waves at the speed of light.
EM Spectrum Regions Used in Remote
Sensing
λ = EM radiation
wavelength
1. Ultraviolet ( λ < 0.4 µm)
2. Visible ( 0.4 µm < λ < 0.7 µm)
3. Reflected IR ( 0.7 µm < λ < 2.8 µm)
4. Emitted (thermal) IR ( 2.4 µm < λ < 20 µm)
5. Microwave ( 1 cm < λ < 1 m)
EMR -How it works
Incident energy from the sun interacts with a specific material and it is
either reflected, scattered, transmitted or absorbed completely.
Emission of electromagnetic radiation occurs as a result of the earth losing
stored energy from within which is produced by either geothermal
heating or stored sun energy.
Remote sensing -Two Stages
STAGES
Data acquisition
Data analysis
Types of remote sensing
TYPES
Framing System
Scanning System
FRAMING SYSTEM
SCANNING SYSTEM
pancromatic
Wide Field Sensors
(WiFS)
Immage Size 774square-kilometer
Return rate
LISS I
LISS 2
LISS III
Bands
Pixel size
Pixel size
Pixel size (resampled to)
0.45-0.52 µm
0.52-0.59 µm
0.62-0.68 µm
0.77-0.86 µm
1.55-1.70 µm
0.5-0.75 µm
72.5 m
72.5 m
72.5 m
72.5 m
36.25
36.25
36.25
36.25
23.5-meter (20 m)
23.5-meter (20 m)
23.5-meter (20 m)
23.5-meter (20 m)
5.8 m (5 m)
0.62-0.68 µm
190 m
0.77-0.86 µm
190 m
22 day
22 day
Swath size
148 km
22 day
74* 2 km or
131km
Altitude
905km
820 km
140 km