Remote Sensing TechnologySatellite and Sensor Characteristics

Remote Sensing Technology
Satellite and Sensor Characteristics
Dr. Abhijit M. Zende
Dr. Daulatrao Aher college of Engineering
Karad
zenabhi31@yahoo.co.in
+91-9822842539
1

DEFINITION:
The Technique Of Acquiring Information About An Object By
Recording Device (sensor) I.E. Not In Physical Contact With The
Object By Measuring Portion Of Reflected Or Emitted
Electromagnetic Radiation From The Earth’s Surface.
2

PRINCIPLE OF REMOTE SENSING:
 Different objects return (reflects or emits) different amount & kind of
energy in different bands of electromagnetic spectrum incident upon it.
 This unique property depends on the structural, chemical, physical
properties of material & also surface roughness, angel of incidence,
intensity & wavelength of radiant energy.
 RS is multidisciplinary science which includes optic, spectroscopic,
photography, computer science, electronics & telecommunication,
satellite tech. etc.
 All these technologies are integrated to act as remote sensing.
3

STAGES IN REMOTE SENSING:
1. Energy source:
Emission of electromagnetic radiation or EMR
(sun/ self emission) .
2. Energy Interactions With Atmosphere:
Transmission of energy from the source to the
surface of the earth as well as ABSORPTION &
SCATTERING.
3. Interaction of EMR With the Earth Surface:
Reflection & emission transmitted or absorbed by
the surface.
6

STAGES IN REMOTE SENSING:
4. Recording of Energy by the Remote Sensor:
Sensor not in touch with the earth’s surface
5. Sensor Data Output:
Data transmission & reception.
6. Data (Image) Processing & Analysis:
Extraction of information @ the earth surface features.
7. Application :
Extracted information is utilized in decision making for
solving problems.
7

TYPES OF RS
1. Based on source of energy
A) PASSIVE SENSORS:
Remote Sensing systems measuring the naturally
available energy ( Solar energy: either reflected or
absorbed) are called as Passive Sensors.
B) ACTIVE SENSORS:
Remote Sensing systems which provides their own
source of energy for illumination are known as
Active Sensors.
e.g. SLAR, SAR
8

TYPES OF RS
2. Based on range of electromagnetic spectrum
A) OPTICAL RS:
RS of Visible, NIR,MIR 0.3 m--3m.
B) THERMAL RS:
RS of emitted radiation 3 m--5m. & 8 m--16m.
C) MICROWAVE RS:
RS in higher wavelength 1mm—1m
9

ADVANTAGES OF RS
 Synoptic View
 Facilitates the study of various earth surface features in their
spatial relation to each other.
 Helps to delineate the reqd. features & phenomenon.
 Accessibility
 Possible to gather information @ the area when
ground survey is not possible.
e.g. Mountainous areas & foreign areas.
10

ADVANTAGES OF RS
 Time conservation
Information @ the large area is gathered quickly saving time efforts of
human.
Multidisciplinary Applications
Remote Sensing data is processed & used in different disciplines like
• GEOLOGY
• FORESTRY
• LANDUSE
• AGRICULTURE
• DEFENCE
• URBAN PLANNING
• FISHERIES
• CIVIL ENGINEERING etc…
11

ELECTROMAGNETIC RADIATION
A) WAVE MODEL.
12

B) PARTICLE THEORY.
Radiation consists of electrical and
magnetic fields perpendicular to each
other, moving in wave pattern.
i) Wavelength ()
ii) Frequency ()
iii) Amplitude (A)
13

ELECTROMAGNETIC SPECTRUM
Representing the continuum of EMR arranged on the basis of wavelength and frequency.
Electromagnetic spectrum ranges as…
Gamma Ray -------------- shorter wavelengths
X-ray
Ultraviolet
Visible spectrum ---------- 400nm—700nm
Infrared
Microwaves
Radiowaves ----------------- Longer wavelength
16

ENERGY INTERACTION WITH THE ATMOSPHERE
Atmosphere affect incoming radiation by
 Scattering : Rayleigh scattering
Mie scattering
Non selective scattering
 Absorption : O3 Ozone
CO2 Carbon Dioxide
H2O Water Vapour
 Refraction : Atmospheric layer of varying clarity, humidity,
temperature.
17

ATMOSPHERIC WINDOWS
 These are the regions in the electromagnetic
spectrum for which the atmosphere is transparent.
 These wavelengths are easily transmitted through
atmosphere.
 These are useful regions for remote sensing.
19

Atmospheric (Absorption / Transmission) windows
0.3-0.4, 0.4-0.7, 0.7-3.0, 3.0-5.0, 8.0-14.0, 1.0cm-1.0m.
ERS : C 5.7 cm
JERS : L 23.5 cm
Atmospheric
Scattering
20

INTERACTIONS OF ENERGY WITH THE EARTH
SURFACE
Radiation not absorbed or scattered in the atmosphere reaches &
interacts with the Earth’s surface.
Reflection :- Light is redirected as it strikes a non-transparent
surface.
 Specular reflection – like mirror is undesirable in RS.
 Diffused Reflection – If surface is rough relative to  useful in RS.
 Transmission & absorption – No reflection.
 Earth’s emission :- Objects at temperature above 0o
emits radiations.
22

REFLECTION CHARACTERISTICS OF EARTH
COVER
It may be qualified by measuring the portion of incident
energy that is reflected.
 Vegetation : Red & Blue colors are absorbed.
Green & NIR are reflected.
 Water : All radiation are absorbed.
Blue or Blue-Green colors are little reflected.
 Soil : Depend on moisture, organic content, texture,
structure, iron oxide content etc.
23

Spectral Reflectance Curves
24

ORBITS OF REMOTE
SENSING
SATELLITE:
Satellite is any object manmade or
natural that revolves around the earth
TYPES OF ORBITS:
•Low Earth Orbit (LEO) < 2000 km
•Medium Earth Orbit (MEO) 2000-35786 km
•High Earth Orbit (HEO) > 35786 km
25

Low Earth Orbit:
Polar orbiting satellites:
•Satellite is pass above the earth
poles
•High resolution of images is
possible
•Crosses the equator at 90⁰
ORBITS OF REMOTE
SENSING
26

Low Earth Orbit:
Polar orbiting satellites:
•The advantage is every time the satellite view the
newer segment on the earth surface because of
earth’s rotation
ORBITS OF REMOTE
SENSING
27

Sun Synchronous Orbit
• Angle of inclination of the
orbit with respect to the sun
through out the year is same
• Always crosses the equator
precisely the same local sun
time
• Mostly used for remote
sensing
ORBITS OF REMOTE
SENSING
28

Sun Synchronous Orbit
ORBITS OF REMOTE
SENSING
29

Near polar orbit
•Orbital plane inclined at
small angle with respect to
the earth rotational axis
ORBITS OF REMOTE SENSING
30

High Earth Orbit
Geo stationary orbit
•The satellite placed in this
orbit is stationary with
respect to the earth
•View the same area of the
earth at all times
•View 50% of global surface
(60⁰N to 60⁰S)
•Orbital period is 24 hours
ORBITS OF REMOTE
SENSING
31

ORBITS OF REMOTE
SENSING
High Earth Orbit Geo
stationary orbit Advantages:
•Useful for meteorological
observation
•And also for commercial
broadcast and
communication purpose
32

ORBITS OF REMOTE
SENSING
High Earth Orbit
Geo stationary orbit
Dis-Advantages:
 Low Resolution
 Approximately a pixel size of
2.5 km on the ground
 Less information is obtained
33

Choice of orbit:
•It is dependent on the its mission
•Remote sensing satellites placed in LEO because it
needs high resolution
•Commercial broadcast or Communication satellites are
provided in HEO because it should receive and send
signals from large geographical are
ORBITS OF REMOTE
SENSING
34

ORBITS OF REMOTE
SENSING
Shapes of orbits:
35

SATELLITES & SENSORS
 PLATFORMS:
Platform is a stage to mount the camera or sensors to collect
information remotely about an object or surface.
e.g. GROUND
BALLOON
AIRCRAFT
SPACE CRAFT/
SATELLITE
37

Types of platforms :
 Ground based platforms
Short range systems(50-100 m) Medium Range Systems ( 150-
250 m) Long range Systems (up to 1 km)
 Airborne platforms
 Space-borne platforms
REMOTE SENSING
PLATFORMS
38

REMOTE SENSING
PLATFORMS
Ground Based Platforms:
Mobile hydraulic platforms (up to 15 m height)
39

REMOTE SENSING
PLATFORMS
Portable Masts
•Unstable in wind conditions
40

REMOTE SENSING
PLATFORMS
Towers:
•Greater rigidity than masts
41

REMOTE SENSING
PLATFORMS
Weather Surveillance Radar
•Detects and tracks
typhoons and cloud masses
42

REMOTE SENSING
PLATFORMS
Airborne Platforms:
Balloons based :
• Altitude range is 22-40 km
• Tool to probing the
atmosphere
• Useful to test the instruments
under development
43

REMOTE SENSING
PLATFORMS
Airborne Platforms:
Radiosonde:
Measure pressure,
Temperature, Relative
humidity and in the
atmosphere
Rawinsonde:
Measure wind velocity,
temperature, presurre and
relative humidity
44

REMOTE SENSING
PLATFORMS
Aircraft: Advantages:
•High spatial resolution (20 cm
or less)
•Analog photography is
possible (analog photo gives
high resolution)
• Easily change their schedule
to avoid weather problems
• Sensor maintenance and
repair is easy
45

REMOTE SENSING
PLATFORMS
Aircraft:
Dis -Advantages:
•Permission to intrude into foreign airspace is
required
•Many passes to cover larger area
•Swath is much less compare to satellite
•High cost per unit area
46

REMOTE SENSING PLATFORMS
Space borne platforms:
•Sensors are mounted
on-board a spacecraft
•Rockets , satellites
and space shuttles
Advantages :
•Cover large area
•Repetitive coverage of
an area of interest
47

REMOTE SENSING SENSORS
Sensor :
Common Definition :
• Sensors are Sophisticated devices that are
frequently used to detect and respond to
electrical or optical signals
• A Sensor converts the Physical parameter into a
signal which can be measured electrically
48

Sensor :
Definition in Remote Sensing :
•Sensor is a device that gathers energy (EMR)
converts into signal and present it into a signal and
present it in a form (image) suitable for obtaining
information about the objet under investigation
49

REMOTE SENSING
SENSORS
Types of sensors :
50

Types of sensors :
Active sensors:
These sensors detect reflected responses from
objects which are irradiated from artificially
generated energy sources
Ex : Radar, camera with flash light Passive sensors:
These sensors detect reflected EMR
from natural source
Ex : camera without flash light (depends on solar
energy), and all RS sensors
51

Types of sensors :
Non Scanning or Framing sensors:
Measure the radiation coming from entire scene at
once
Ex: Our eyes, Photo cameras
52

Types of sensors :
Imaging sensors:
Form image by collected
radiation
1. Scanning sensors:
The scene is sensed by point
by point or measure the
radiation coming from point
by point (equivalent to small
areas with in the scene)
Along track Scanners:
Image is acquired by line by
line
53

Types of sensors :
Across track Scanners:
Image is acquired by pixel by pixel
54

Types of sensors :
2. Non imaging sensors:
•These sensors do not form the image
•These are used to record spectral quantity or
parameter as a function of time
Ex: temperature measurement, study of
atmosphere
55

Types of sensors :
Image Plane Scanning:
Lens is used after the
scan mirror to focus
the light on the
detector
56

Types of sensors :
 Object Plane Scanning: Lens is
placed before the scan mirror
to focus the light on the
detector
57

Characteristics of Sensors
1. Spatial resolution
2. Spectral resolution
3. Radiometric resolution
4. Temporal resolution
58

CHARECTERISTICS OF
SENSORS
Spatial resolution
•It refers to the size of the
smallest possible object that
can be detected
•It depends on the
instantaneous Field of View
(IFOV) and the height of the
satellite orbit
•It tells the pixel size
on the ground surface
59

CHARECTERISTICS OF
SENSORS
Spatial resolution
60

CHARECTERISTICS OF
SENSORS
Spatial resolution
61

CHARECTERISTICS OF
SENSORS
Spatial resolution
62

Spectral resolution
•It describes the ability of a sensor to define fine
wavelength ranges
•Sand is appear as coarser in finer
wavelength bands
63

Radiometric resolution
•It describes the abilityof sensor to
discriminate very slight differences in energy
•The number of brightness levels depends upon the
number of bits used
64

CHARECTERISTICS OF
SENSORS
Radiometric resolution
65

CHARECTERISTICS OF SENSORS
Temporal resolution
It refers to how often it records imagery of a
particular area, which means the frequency
of repetitive coverage
66

SATELLITE ORBIT
 Path followed by the satellite.
 Geostationary satellite :-
1. Revolve at the speed matching the rotation of the
Earth( 24 hours ).
2. Located at very high altitudes about 36000Km.
3. Are put in the equatorial plane orbiting West to East.
4. One satellite can view one-third of the globe.
5. Used for weather monitoring & communication
(INSAT, V-Sat).
67

8/23/2016 EngineeringApplications of RS and
GIS
39
68

SUN-SYNCHRONOUS SATELLITES
 Inclined North-South orbit.
 Inclination carries the satellite Westward.
 Its track covers each area of the world at a Constant
time of the day (local sun time ).
 Descending pass – day
 Ascending pass – shadow ( night )
 Payload of passive sensors.
 Active sensors can acquire image in
ascending pass also.
69

5/29/03 Engineering Applications of RS and
GIS
34
70

Sun-Synchronous (Polar orbiting) : Remote Sensing Satellites
Geo-Synchronous (Equatorial Orbiting) Satellites :
Telecommunications / Weather
Day-Time
Descending
Path
Night-Time
Ascending
Path
71

SWATH (Two Dimensional Image of
Earth Surface For An Area )
• As a satellite revolve around the Earth, the sensors see a certain portion of
Earth surface known as swath.
• For satellite images it is very wide between 10 -100 Km.
• The apparent Westward shift of satellite (due to Earth’s rotation ) allows
the satellite Swath to cover a new area with each pass.
72

5/29/03 Engineering Applications of RS and
GIS
43
73

1. Ground Segment
(Receiving Antenna)
2. Satellite Path
(Data Acquisition)
3. Successive Paths
(Gap between Paths)
4 Stereoscopic
Data Acquisition
1 2
3 4
74

RESOLUTION
It refers to the system’s ability to record & display fine details.
In RS there are four types of resolution,…
 Spatial resolution
 Spectral resolution
 Radiometric resolution
 Temporal resolution.
Spatial resolution :- The size of the smallest possible feature that can
be detected by the sensors.
76

 Spectral resolution :- It describes the ability of a sensors to define
fine wavelength intervals. Many RS systems record energy over
several separate wavelengths ranges at various spectral resolution.
These are multispectral scanners. Advanced multispectral sensors
detect hundreds of very narrow spectral bands through the
spectrum.
 Radiometric resolution :- Every time an image is acquired on film
or by a sensor, its sensitivity to the magnitude of the
electromagnetic energy determines the radiometric resolution.
 The radiometric resolution of an imaging system describes its
ability to discriminate very slight differences in the energy.
77

 Temporal resolution :- Temporal resolution refers to the frequency of
obtaining data over a given area. It is related to the revisit period or
repeativity.
78

Spatial Resolution
30m : LS-TM, 80m : LS-MSS
79

Spatial Resolution
10m : SPOT-PLA, 20m : SPOT-MLA
80

MULTISPECTRAL SCANNING
A scanning system that is useful to collect data over a range of
wavelengths is called MSS.
Across track scanning Along track scanning
scan lines ar
to scan lines Ilel
to
motion of system motion of system
86

SATELLITE IN ORBITS
LANDSAT
NASA ( National Aeronautic & Space Administration ) launched the
LANDSAT series. It is Land Observation Satellite Series.
 RBV :- Return Beam vidicon.
 MSS :- Multispectral scanner. Across track, 4 spectral band data
with 80 meters resolution & 6 bits radiometric resolution.
 TM :- Thematic map per, 7 ban data for 6 bands, spatial
resolution of 30 metres & for thermal band, 120 metres,
 ETM :- Enhanced Thematic map per, 8 band data.
 Swath :- 185 Km.
87

Spot Satellite
Altitude :- 832 Km.
Revisit :- 26 days.
Payload :-
HRV – High resolution visible sensor.
i ) PAN mode 10 m,
i i ) MSS mode 20 m.
HRVIR – Spot 4 – 10 m resolution
VEGETATION – Spot 4 – 1.165 Km resolution.
88

INDIAN REMOTE SENSING SATELLITE
OBS.
NO.
MISSIONS SENSORS ALTITUDE
(Km)
REVISIT
(DAYS)
1.
IRS-1A
LISS – I
LISS – II
904 22
2. IRS-1B
LISS – I
LISS – II
904 22
3. IRS-1C
PAN
LISS–III
WIFS
817
05
24
05
89

4 IRS- 1D
PAN
LISS-III
WIFS
817
05
24
05
5 IRS- P2 LISS-II 817 24
6 IRS- P3
WIFS
MOS
ASTRO-
-NOMY
817 24
7 IRS- P4
OCR
MSMR 727 03
90

OBS.
NO.
SENSOR SPECTRAL
RES.
SPATIAL
RES.
SWATH
1. LISS-I 4 BAND 72.50 M 148.0 KM
2. LISS-II 4 BAND 36.25 M 074.0 KM
3. LISS-III 4 BAND 23.50 M 141.0 KM
4. PAN SINGLE
BAND
05.80 M 070.0 KM
5. WIFS 2 BAND 188.0 M 810.0 KM
93

Remote Sensing Satellites and Sensors
 Landsat : 1, 2, 4,5,7 : MSS : 2 VIS+2 NIR
 3. MSS : 2 VIS+2 NIR+1TIR
 Landsat 4,5,7 : Bands :1,2,3,4,5,7 VIS and NIR
 Band 6 : TIR
 IRS – 1A/1B-LISSI/II, 1C/1D-LISS-III
4 Bands : 2 VIS + 2 NIR
 SPOT : MLA : 3 bands, PLA : 1 Band (PAN)
 ERS Microwave SAR
 JERS Microwave SAR
102

SATELLITE DATA RECEPTION TRANSMISSION &
PROCESSING
Three main options form transmitting data acquired by
the satellite to the surface.
 Data can be directly transmitted to the earth if a Ground
Receiving Station (GRS) is in the line of sight of the
structure.
 Data can be recorded on board the satellite for
transmission to a GRS at later time.
 Data can also be relayed to the GRS through the TDRSS
( Tracking & Data Relay Satellite System ) which
contains series of Geosynchronous, communication
satellite .
103

In India
GRS is located at Shadnagar. NRSA ( National
Remote Sensing Agency ) acquires process, & distribute
the satellite data from Indian as well as other satellites.
Satellite (IRS,LANDSAT, SPOT, NOAA, IKONOS )
GRS ( Shadnagar – data in raw digital format )
NRSA (processing to correct errors & Convert to standard
format )
104

DIGITAL IMAGE PROCESSING
i.e. manipulation of the images with the help of a computer
system.
Hardware software
monitor, ( categorization into
CPU three main functions)
secondary storage device 1. Image processing
( floppy disc drive, 2. Image enhancement
hard disc, scanners, etc) 3. Image classification
105

IMAGE PROCESSING
Preliminary to the main analysis :-
Removal of error introduced in the imaging.
Processes are designed to recognize &
compensate for ,…
Errors
Noise
Geometric distortions,
introduced into the data during the scanning,
transmission & recording processes.
106

PREPROCESSING
 Radiometric corrections
 Atmospheric corrections
 Geometric corrections
1. Radiometric correction :- Radiometric
errors are caused by detector
imbalance & atmospheric deficiencies.
Radiometric corrections are transmitted
on the data in order to remove errors,
which are atmospheric correction.
107

geometrically independent. Radiometric corrections
are also called as. Cosmetic corrections & are done to improve
the visual appearance of the image.
Some Radiometric corrections are ,…
correction of missing scan line
correction for periodic line striping
random noise corrections
108

2. Atmospheric corrections :- True ground-leaving
radiance is altered by scattering & hence it needs
corrections.
3. Geometric corrections :- The transformation of
remotely sensed images so as it has a scale & projections
of a map .is called as Geometric correction. Systematic
& nonsystematic disorders are corrected.
109

IMAGE ENHANCEMENT
Image enhancement technique improve the quality & appearance
of an image for human visual analysis & subsequently for machine
also.
Common techniques are …
• Contrast stretch ,… linear & nonlinear
• Spatial filtering
• Band rationing
• principal component analysis
110

Visual Interpretation
 The digital data can be transformed to Photographic Images
 B&W individual Band Images or 3-band Colour Composites
 Elements : Tone / Colour, Texture, Pattern, Association, Shape, Size, Shadow.
 Tone / Colour represents the reflectance of the terrain feature in a given
spectral band : Black to White gray shades / levels or Blue, Green, Red, Yellow
Magenta, Cyan, colours.
 Texture refers to the aggregation of tones or repetition of tones in spatial
context : fine (water, grass, paddy, wheat, sand, etc.), Coarse (hills & valleys,
forests, urban areas, etc.) and Medium (other).
 Pattern refers to the spatial arrangement of objects : Urban, agriculture, hilly,
water, Roads, Railways, Canals, etc.
 Shape, size and shadow : aid in the recognition of the features and therefore in
interpretation of their significance
 Multi-Thematic Maps : derived from Aerial Photographs : Topography :
elevations, slope, Drainage, Soils, Geology, landuse, etc.
111

Plate 7.a Landsat 5 TM band 2 (green) image. Plate 7.b Landsat 5 TM band 3 (red) image
Plate 7.c Landsat 5 TM band 4 (near infrared) image
Plate 7.d FCC:Landsat 5 TM band 2,3 and 4.(Band 4, 3 and 2 as RGB)
112

Plate 1.a IRS-LISS-II Band 2 Image Plate 1b. IRS-LII-II band 3 Image
Plate 1. c IRS-LISS-II Band 4 Image Plate 2. FCC (IRS 1A LISS-II : (bands 4,3 and 2 as RGB)
113

Photo/Image Interpretation Elements
TONE
114

Tone Photo Interpretation Elements Texture
115

Photo Interpretation Elements
Pattern
116

Photo Interpretation Elements
Shadow
117

IMAGE CLASSIFICATION
We normally categorize the objects on the Earth’s surface as
forest, agriculture field, river, settlements etc.
Digital image classification is the process of assigning pixels to
classes. These classes represents regions on the image or map & are
identified by the number or symbol.
classification
supervised unsupervised
118

Supervised : It is the process of known identity (trained
pixels ) to classify the pixels, whose identity is not known.
Unsupervised :classifiers do not utilized training data as basis
of classification; classes are spectral classes; need of reference
data to identify informational value of the spectral class.
Sample area known as training areas. Statistics are calculated
for training sites. And every pixels within & outside the
training site is assigned to a class or category it most likely
resembles.
119

DIFFERENT PHASES IN SUPERVISED CLASSIFICATION
 Appropriate classification scheme for analysis is adopted.
 Selection of representative training site & collection of
spectral signatures.
 Evaluation of statistics for the training site spectrum data.
 The statistics are analyzed to select the appropriate features
( bands ) to be used in the classification process.
 Appropriate classification algorithm is selected.
 Classify the image into N classes.
 Statistically analyze & evaluate the classification scheme.
120

Thane Creek : Turbid Water
Tulsi Lake : Clear Water
Vihar Lake : Clear Water
Powai Lake : Clear Water
IIT Campus
Forest around National
Park Borivali
Barren land
Salt Pans
Mangroves
Urban – Mixed Area
Eastern Express Highway
Central Railway
Lal Bahadur Shastri Marg
Mumbai – Thane Creek Area : Landuse-Landcover details
121

Classified MS image (MLH)
(IRS-LISS-II Bands 4,3,2)
WATER
LIGHT VEG.
THICK VEG.
MARSHY
URBAN
BARREN
TURBID
LEGEND
SALT PANS
122

Thermal IR-Sensing
 Thermal Ranges:3 to 5 and 8 to15 m.
 Emittance :Radiation, Day and Night Temperature Changes, Emittances of
terrain features.
 Radiometers and Scanners (Cooled Detectors): Low-Energy, Coarse-
Resolutions : Spatial and Spectral.
 Day and Night Time Thermal Images : Geology, Geo-Thermal, Volcanic,
Fires,.Thermal pollution, , etc.
 Thermal Data : Landsat-3 : Band-8, Landsat- 4 / 5 : Band 6. Day and Night -
time.
 Interpretation : Cool : Dark (low emittances), Hot : Bright (high emittances)
123

Landsat 5TM Daytime and Nighttime TIR Registered Data
124

Remote Sensing Technology Satellite and Sensor Characteristics

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