RS

REMOTE SENSING

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.

PRINCIPLE OF REMOTE SENSING

PROCESS OF REMOTE SENSING

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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.

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.

TYPES OF RS

A) Types of RS Based on Source of Energy

1. PASSIVE SENSORS

Remote Sensing systems measuring the naturally available energy ( Solar energy: either reflected or absorbed) are called as Passive Sensors.

2. ACTIVE SENSORS

Remote Sensing systems which provides their own source of energy for illumination are known as ‘Active Sensors’. e.g.

  1. SLAR: Side looking airborne radar
  2. SAR: Synthetic Apareture Radar

B) Based on range of electromagnetic spectrum

1. OPTICAL RS

RS of Visible, NIR,MIR 0.3 um - 3 um.

2. THERMAL RS

RS of emitted radiation 3 um - 5 um. & 8 um - 16 um.

3. MICROWAVE RS

RS in higher wavelength 1mm—1m

ADVANTAGES OF RS

Synoptic View

Accessibility

Possible to gather information at the area when ground survey is not possible. e.g. Mountainous areas & foreign areas.

Time conservation

Information at the large area is gathered quickly saving time efforts of human.

Multidisciplinary Applications

Remote Sensing data is processed & used in different disciplines like (Applications og GIS)

ELECTROMAGNETIC RADIATION

1. WAVE MODEL

2. PARTICLE THEORY

Radiation consists of electrical and magnetic fields perpendicular to each other, moving in wave pattern.

ELECTROMAGNETIC SPECTRUM

EM-Spectrum

Representing the continuum of EMR arranged on the basis of wavelength and frequency.

Electromagnetic spectrum ranges as…

  1. Gamma Ray ————— shorter wavelengths
  2. X-ray
  3. Ultraviolet
  4. Visible spectrum ———- 400nm—700nm
  5. Infrared
  6. Microwaves
  7. Radiowaves ————— Longer wavelength

ENERGY INTERACTION WITH THE ATMOSPHERE

Atmosphere affect incoming radiation by

Atmospheric-Interaction

ATMOSPHERIC WINDOWS

Atmospheric-Window

Atmospheric-Window-2

REFLECTION CHARACTERISTICS OF EARTH COVER

It may be qualified by measuring the portion of incident energy that is reflected. Vegetation

Water :

Soil :

Spectral Reflectance Curves

Reflectance-Curves

SATELLITES & SENSORS

PLATFORMS

Platform is a stage to mount the camera or sensors to collect informationremotely about an object or surface.

TYPES OF PLATFORM

SATELLITE ORBIT

1. 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).
  6. Geo-Synchronous (Equatorial Orbiting) Satellites : Telecommunications, Weather

Satellite-Orbit-Geo

2. SUN-SNYCHRONOUS SATELLITE

  1. Inclined ‘North-South’ orbit.
  2. Inclination carries the satellite Westward.
  3. Its track covers each area of the world at a Constant time of the day ( local sun time ).
  4. Descending pass of sun-synchronous satellites – day
  5. Ascending pass of sun-synchronous satellites – shadow ( night )
  6. Payload of passive sensors.
  7. Active sensors can acquire image in ascending pass also.

Satellite-Orbit-Sun

Day Pass(Sun-Synchronous) Night Pass(Sun-Synchronous)
Satellite-Orbit-Sun-Day Satellite-Orbit-Sun-Night
Day Pass : Descending Night Pass : Ascending

SWATH (Two Dimensional Image of Earth Surface For An Area)

Q. What is SWATH?

SWATH

SWATH STAGES SWATH STAGES
SWATH SWATH
1. Ground Segment (Recieving Antenna) 2. Satellite Path (Data Acquisition)
SWATH SWATH
3. Successive Paths (Gap between Paths) 4 Stereoscopic Data Acquisition

List of Satellites

Satellites

RESOLUTION

It refers to the system’s ability to Record & Display Fine Details. In Remote Sensing there are Four Types of Resolution

TYPES OF RESOLUTION

Spatial Resolution Diagrams:

DIAGRAM SENSOR(Meter)
SWATH 30m : LS-TM, 80m : LS-MSS
SWATH 10m : SPOT-PLA, 20m : SPOT-MLA

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 Perpendicular to motion of system scan lines Parallel to motion of system

SATELLITE IN ORBITS

LANDSAT SATELLITE

NASA (National Aeronautic & Space Administration) launched the LANDSAT series. It is Land Observation Satellite Series.

SPOT SATELLITE

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 817 05
    LISS-III 817 24
    WIFS 817 05
4. IRS-1D PAN 817 05
    LISS-III 817 24
    WIFS 817 05
5. IRS-P2 LISS-III 817 24
6. IRS-P3 WIFS 817 05
    MOS 817 05
    ASTRONOMY 817 05
7. IRS-P4 OCR 727 03
    MSMR 727 03

INDIAN REMOTE SENSING SATELLITE SENSORS LIST

OBS. NO. SENSORS SPECTRAL RESOLUTION SPATIAL RESOLUTION SWATH
1. LISS-I 4 BANDS 72.50M 148 KM
2. LISS-II 4 BANDS 36.25M 074 KM
3. LISS-III 4 BANDS 23.50M 141 KM
4. PAN 1 BANDS 05.80M 070 KM
5. WIFS 2 BANDS 188.0M 810 KM

REMOTE SENSING SATELLITE AND SENSORS LIST

SATELLITE VERSION MULTI SPRECTRAL SENSORS
LANDSAT 1,2,4,5,7 MSS: 2VIS + 2NIR
LANDSAT 3 MSS: 2VIS + 2NIR + 1 TIR
LANDSAT 4,5,7 BANDS: 1,2,3,4,5,7 VIS & NIR
LANDSAT 4,5,7 BANDS: 6 - TIR
IRS 1A/1B LISS-I/II
IRS 1C/1D LISS-I/III 4 BANDS: 2VIS+2NIR
SPOT MLA 3 BANDS
SPOT PLA 1 BAND (PAN)
ERS   MICROWAVE SAR
JERS   MICROWAVE SAR

SATELLITE DATA RECEPTION, TRANSMISSION & PROCESSING

  1. Data can be directly transmitted to the earth if a Ground Receiving Station (GRS) is in the line of sight of the structure.
  2. Data can be recorded on board the satellite for transmission to a GRS at later time.
  3. Data can also be relayed to the GRS through the TDRSS( Tracking & Data Relay Satellite System ) which contains series of Geosynchronous, communication satellite.

GRS 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.

Data tranmission Stages

Satellite (IRS,LANDSAT, SPOT,NOAA, IKONOS ) to GRS ( Shadnagar – data in raw digital format ) to NRSA (processing to correct errors & Convert to standard format )

DIGITAL IMAGE PROCESSING

What is Digital Image Processing

Image Processing is manipulation of the images with the help of a Computer System.

HARDWARE SOFTWARE
MONITOR 1. Image Processing
CPU 2. Image Enhancement
Secondary Storage Devices 3. Image Classification
Floppy Disc, Hard Disc, Scanner etc.  

1. IMAGE PROCESSING

Preliminary to the main analysis :-

PREPROCESSING

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. Rediometric corrections are geometrically independent. Radiometric corrections are also called as Cosmetic corrections Rediometric corrections are done to improve the appearance of the image.

Examples of Radiometric Correction

Atmospheric corrections

True ground-leaving radiance is altered by scattering & hence it needs corrections these corrections are called as Atmospheric corrections.

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 in Geometric Correction.

2. IMAGE ENHANCEMENT

Image enhancement technique improves the quality & appearance of an image for human visual analysis & subsequently for machine also. Common techniques are:

Photo Interpretation Elements / Image Interpretation Elements

  1. SIZE
  2. SHAPE
  3. SHADOW
  4. TONE
  5. COLOR
  6. TEXTURE
  7. PATTERN
TONE IMAGE

TONE

TEXTURE IMAGE

TONE

PATTERN IMAGE

TONE

SHADOW IMAGE

TONE

3. 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 TYPES

  1. SUPERVISED
  2. UN-SUPERVISED
1. SUPERVISED

Supervised Image Classification is the process of known identity (trained pixels ) to classify the pixels, whose identity is not known.

DIFFERENT PHASES IN SUPERVISED CLASSIFICATION
2. UN-SUPERVISED

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.

THERMAL IR SENSING

REMOTE SENSING APPLICATIONS

REMOTE SENSING APPLICATIONS

REMOTE SENSING

GIS

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