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Overview of Remote Sensing technology                          Shefali Agrawal             Photogrammetry and Remote Sensi...
The Remote Sensing ProcessEnergy Source                    Sensor                                SatCom                   ...
The size of a cell we call image resolution, depending on… Such as 1 m, 30 m, 1 km, or 4 km           Types of remote sens...
Remote sensing is classified into three types with respect      to the wavelength regions;    • Visible and Reflective Inf...
Atmospheric windows suitable for Earth observations           from space,Atmospheretransmission (%)  100   50    0        ...
•  For example A white surface reflects equal amounts of  radiation of all wavelengths of visible light.• A green object r...
Spectral Reflectance Characteristics of      Leaves
Spectral Reflectance of Snow
(a)                                                                   (b) IRS LISS-3 image over part of Himalayas. (a) is ...
Platforms   Sensing from 1 meter to 36,000 km   height   Platforms are:        •Ground based        •Airborne        •Spac...
Space borne remote sensing                                                                  Spot off nadir                ...
Polar Orbits                                 An orbit with a inclination of 90                                 degrees, or...
Selection of Sensor Parameters Information collected by sensor should be sufficient enough to meet accuracy in class discr...
Spatial Resolution SPATIAL     -      THE PHYSICAL DIMENSION ON                    EARTH IS RECORDED : SPATIAL            ...
ETM (30 m)IRS-LISS III (23.5 m)
ASTER(15 m)IRS-PAN (5.8 m)
IKONOS MSS (4 m)IKONOS PAN (1 m)
Spectral ResolutionSPECTRAL-                Relating of wavelength                         characteristics of EMR measured...
Colour Composite True Color Composite (3,2,1)   False Color Composite          IR Colour Composite                        ...
Radiometric ResolutionLow Radiometric resolution         High Radiometric resolution                Temporal Resolution• H...
INDIAN IMAGING CAPABILITY               •1 Km to 1 m spatial Resolution               •24 Days to every 30 mts. Repetitivi...
IRS-1C/1D Mission                      Sensors                              • LISS-III• PAN                           – Op...
IRS Resourcesat (P6) Payloads      LISS-3: 141 km swath, 23.5 m resolution (all bands).           –   B2: 0.52 - 0.59     ...
RESOURCESAT-1 LISS-IV MX IMAGE OF MUMBAI           Cartosat-1 PAN Sensor      Real time stereo viewing                    ...
ON   -      ORBIT CONFIGURATION OF CARTOSAT- 2SATELLITEPAYLOAD : PAN     : 0.8 M          SWATH   : 9.6K MSPACECRAFT WEIGH...
IRS P6 LISS IV(5.8m) MSS and CARTOSAT(2.5m) PAN FUSED             Cartosat 1 : Chandigarh
Hyderabad (Khairatabad and its environs), India as seen by CARTOSAT-2         Perth Airport, Australia as seen by CARTOSAT-2
IKONOS SATELLITE DETAILSPAYLOAD :PAN      : I M RESOLUTION            MS    : 4 M, 4 BANDS          SWATH   : 11 KMSSPACEC...
ORBVIEW 5 (GEOEYE 1          -         - )  PAYLOAD            : PAN & MS CAMERA                       0.41 M PAN         ...
RADAR Images             ERS SAR image (pixel size=12.5 m)Flat surfaces such as paved roads, runways or calm waternormally...
Microwave images           This SAR image shows an area of the sea near           a busy port. Many ships can be seen as b...
PhotogrammetrySTEREOSCOPIC COVERAGE    sidelap   endlap
StereoViewAnaglyph viewing system
Digital Elevation ModelTriangulated Irregular Network
Contours             3D mapping from Cartosat-1 stereo DatasetPI: Ashutosh Bhardwaj, IIRS, Dehradun
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  1. 1. Overview of Remote Sensing technology Shefali Agrawal Photogrammetry and Remote Sensing Division IIRS Email: shefali_a@iirs.gov.in What Is Remote Sensing? Technique of obtaining information about an object, area, or phenomenon from a distance Remote sensing is the process of collecting data about objects or landscape features without coming into direct physical contact with them. In its broadest sense it refers to the activities of recording/observing/perceiving (sensing) objects or events at far away (remote) places• “Science of measuring the GEOMETRIC and THEMATIC properties of objects in the environment without touching them and using various devices in the air or space”• It is the technique of collecting information from a distance• “From a distance” is generally considered to be large relative to what a person can reach out and touch
  2. 2. The Remote Sensing ProcessEnergy Source Sensor SatCom Application Target Processing Station Analysis The EM spectrum ‘Optical range’ Cosmic Gamma X- Radio Electric power U-V Infrared Micro-waves TV rays rays Rays Visible spectrum Ultraviolet Blue Green Red Infrared (IR) 0.3μm 0.4 0.5μm 0.6 0.7μm 10.0 15.0 300nm 500nm 700nm Wavelength
  3. 3. The size of a cell we call image resolution, depending on… Such as 1 m, 30 m, 1 km, or 4 km Types of remote sensing• Passive: source of • Active: source of energy is either the Sun, energy is part of the Earth, or atmosphere remote sensor system – Sun – Radar - wavelengths: 0.4-5 µm - wavelengths: mm-m – Earth or its atmosphere – Lidar - wavelengths: 3 µm -30 - wavelengths: UV, cm Visible, and near infrared
  4. 4. Remote sensing is classified into three types with respect to the wavelength regions; • Visible and Reflective Infrared Remote Sensing, 0.4µm to 3 µm • Thermal Infrared Remote Sensing and 3 µm to 35 µm • Microwave Remote Sensing, 1mm to 1m Interactions with the Atmosphere The two major atmospheric effects are scattering and absorption A) Scattering B) Absorption⇒ Scattering occurs when particles or large gas molecules present in the atmosphere interact with and cause the electromagnetic radiation to be redirected from its original path⇒ Absorbption causes molecules in the atmosphere to absorb energy at various wavelengths. Ozone, carbon dioxide, and water vapour are the three main atmospheric constituents which absorb radiation
  5. 5. Atmospheric windows suitable for Earth observations from space,Atmospheretransmission (%) 100 50 0 0.4 0.7 1 2 3 5 10 (...) 10,000 µm Interactions with the surface Sunscattered Incident energyradiation** R.S. Instrument Scattered Atmospheric Clouds radiation* emission Atmospheric transmitted Reflected Thermal emission absorption radiation radiation Earth Reflection processes Emission processes
  6. 6. • For example A white surface reflects equal amounts of radiation of all wavelengths of visible light.• A green object reflects less in red and blue parts of the spectrum than in green. The excess reflection in green wavelength makes makes the object appear green.• So, the composition of electromagnetic reflection (spectral signature )tells us about the surface reflecting the radiation. Spectral reflectance of vegetation
  7. 7. Spectral Reflectance Characteristics of Leaves
  8. 8. Spectral Reflectance of Snow
  9. 9. (a) (b) IRS LISS-3 image over part of Himalayas. (a) is in band-2 (Green) and (b) in band-5 (SWIR).Both cloud and snow have higher reflectance in visible and hence cannot be discriminated(except from shadow). In SWIR, low reflectance of snow can discriminate snow from cloud.
  10. 10. Platforms Sensing from 1 meter to 36,000 km height Platforms are: •Ground based •Airborne •Spaceborne
  11. 11. Space borne remote sensing Spot off nadir Geostationary Orbit A satellite that appears to remain in the same position above the Earth is called a "geostationary satellite."Credit: C.M.Kishtawal, SAC
  12. 12. Polar Orbits An orbit with a inclination of 90 degrees, or close to it, is called a "polar orbit." Because the Earth is rotating as the satellite follows a polar orbit, the satellite can survey the whole of the Earths surface, including the poles, in a few days. Many observation satellites that need to cover the entire Earth are in polar or near-polar orbits.Credit: C.M.Kishtawal, SAC
  13. 13. Selection of Sensor Parameters Information collected by sensor should be sufficient enough to meet accuracy in class discrimination and mapping.• Spatial resolution• Spectral resolution λ• (Radiometric resolution)• Temporal resolution (revisit time) 1/
  14. 14. Spatial Resolution SPATIAL - THE PHYSICAL DIMENSION ON EARTH IS RECORDED : SPATIAL RESOLUTION• Spatial resolution refers to the amount of detail thatcan be detected by a sensor.• Detailed mapping of land use practices requires amuch greater spatial resolution than observations of alarge scale storm system. AWIFS (56 m)
  15. 15. ETM (30 m)IRS-LISS III (23.5 m)
  16. 16. ASTER(15 m)IRS-PAN (5.8 m)
  17. 17. IKONOS MSS (4 m)IKONOS PAN (1 m)
  18. 18. Spectral ResolutionSPECTRAL- Relating of wavelength characteristics of EMR measured number of bands, bandwidth: spectral resolution•Describes the ability of a sensor to define finewavelengths intervals•The finer the spectral resolution, narrower thewavelength range of a particular band Spectral Bands : LANDSAT TM Band (.45 to .515μm) Band (.525 to .605 μm) Band (.63 to .690 μm) Band (.75 to .90 μm) Band (1.55 to 1.75 μm) Band (2.09 to 2.35μm)
  19. 19. Colour Composite True Color Composite (3,2,1) False Color Composite IR Colour Composite (4,3,2) (7,5,4) Radiometric Resolution • Measure of capability of sensor to differentiate the smallest change in spectral reflectance of a earth feature. High D For same reflectance, N High RR :DN = 4096(12) slope Low RR DN = 64 (6 bit) | 0 reflectance 1.0
  20. 20. Radiometric ResolutionLow Radiometric resolution High Radiometric resolution Temporal Resolution• High TR enhances utility of mission• Key Factors deciding orbit repetivity – Cross-track width of imaging strip – Application demand • Meteorological - hourly need to monitor clouds • Oceanographic - 2-3 days of repetivity • Stereo viewing - 0-1 days of repetivity • Vegetation monitoring - 5 days of repetivity
  21. 21. INDIAN IMAGING CAPABILITY •1 Km to 1 m spatial Resolution •24 Days to every 30 mts. Repetitivity •1 Million scale to Cadastral Level IRS-1A/1B sensorsIRS-1A was launched in 1988 and provided data up to 1992IRS-1B launched in 1991 and continues to provide good quality data till date • LISS-I – Operates in 4 bands in the visible and near infrared regions – Resolution 72 m – Swath 148 km • LISS-II – Operates in same 4 bands as LISS-I – Resolution 36.5 m – Swath 74 km
  22. 22. IRS-1C/1D Mission Sensors • LISS-III• PAN – Operates in 4 bands (3 in visible and near infrared and 1 band in – Operates in one visible shortwave infrared) band – Resolution 23 m – High resolution 5.8 m – Swath 141 km – Swath 70 km at nadir – 90 km off nadir • WiFS – Tilt capability +/- 26 – Operates in 2 bands in visible and Degrees near infrared – Resolution 188 m – Swath 810 km Indian Remote Sensing Satellite Resourcesat (IRS P6)
  23. 23. IRS Resourcesat (P6) Payloads LISS-3: 141 km swath, 23.5 m resolution (all bands). – B2: 0.52 - 0.59 – B3: 0.62 - 0.68 – B4: 0.76 – 0.86 – B5:1.55 – 1.70 LISS-4: 23.5 km (Mx mode) & 70.3 km (mono) swath, 5.8 m resolution (all bands). – B2: 0.52 - 0.59 – B3: 0.62 - 0.68 – B4: 0.76 – 0.86 AWiFS: 737 km combined swath, 56 m resolution at nadir, 70 m resolution at field edges. – B2: 0.52 - 0.59 – B3: 0.62 - 0.68 – B4: 0.76 – 0.86 – B5: 1.55 – 1.70 LISS-4 Sensor – Sensor: 12 K CCD per band – Spectral bands: 3 bands (0.52- 0.59, 0.62- 0.68 and 0.77- 0.86μ) – Swath, MSS Mode: 23.9 km, selectable over 70 Km – Swath, Pan Mode: 70 km in red band – Ground Resolution: 5.8 meter pixel in all 3 bands – Radiometric Resolution: 7 Bits selectable over 10bits – Steering Capability: ± 26 degrees – BBR: < 0.25 pixel – Revisit Capability: 5 days
  24. 24. RESOURCESAT-1 LISS-IV MX IMAGE OF MUMBAI Cartosat-1 PAN Sensor Real time stereo viewing SPATIAL RESOLUTION 2.5 m Satellite Path Two Pan cameras - fore with 26 deg. and aft with -5 deg. Tilt( 500 nm- 850 Fore look Aft look nm) Swath 27.5 km for stereo and 55 km for monoscopic mode. 8 km overlap between adjacent paths 10 bits Facility for across track tilt to give better revisit
  25. 25. ON - ORBIT CONFIGURATION OF CARTOSAT- 2SATELLITEPAYLOAD : PAN : 0.8 M SWATH : 9.6K MSPACECRAFT WEIGHT: 680 KGSORBIT : 632 KMREVISIT : 4/5 DAYSEQUATORIAL CROSSOVER TIME : 9:30 AMLAUNCHED ON : 10TH JAN 2007 CARTOSAT PANCHROMATIC DATA (2.5 M) IIRS
  26. 26. IRS P6 LISS IV(5.8m) MSS and CARTOSAT(2.5m) PAN FUSED Cartosat 1 : Chandigarh
  27. 27. Hyderabad (Khairatabad and its environs), India as seen by CARTOSAT-2 Perth Airport, Australia as seen by CARTOSAT-2
  28. 28. IKONOS SATELLITE DETAILSPAYLOAD :PAN : I M RESOLUTION MS : 4 M, 4 BANDS SWATH : 11 KMSSPACECRAFT MASS : 720 KGSORBIT : 680 KMREVISIT : EVERY 3 DAYSEQUATORIAL CROSSOVER TIME : 10:30AMLAUNCH DATE : SEPTEMBER 1999
  29. 29. ORBVIEW 5 (GEOEYE 1 - - ) PAYLOAD : PAN & MS CAMERA 0.41 M PAN 1.64 M MS IN 4 BANDS SWATH : 15.2 KM DYNAMIC RANGE : 11 BITS ORBIT : 684 KM REVISIT : < 3 DAYS EQUATORIAL CROSS OVER TIME : 10:30 AM LAUNCH DATE : 2007Thermal Images Day time Night time
  30. 30. RADAR Images ERS SAR image (pixel size=12.5 m)Flat surfaces such as paved roads, runways or calm waternormally appear as dark areas in a radar image since most of theincident radar pulses are specularly reflected away.
  31. 31. Microwave images This SAR image shows an area of the sea near a busy port. Many ships can be seen as bright spots in this image due to corner reflection. The sea is calm, and hence the ships can be easily detected against the dark background
  32. 32. PhotogrammetrySTEREOSCOPIC COVERAGE sidelap endlap
  33. 33. StereoViewAnaglyph viewing system
  34. 34. Digital Elevation ModelTriangulated Irregular Network
  35. 35. Contours 3D mapping from Cartosat-1 stereo DatasetPI: Ashutosh Bhardwaj, IIRS, Dehradun

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