Satellite Remote Sensing 1. Types of Remote Sensing Based on Source of Energy Platform 2. Types of Satellite 3. Types of Sensors4. Limitations of Remote Sensing5. Basic Components of an Ideal Remote Sensing System6. Resolution Definition and types.
Introduction to Remote sensingRS System capture radiation in different wavelengthreflected/ emitted by the earth’s surface features andrecorded it either directly on the film as in case of aerialphotography or in digital medium letter is used for generatingthe images. R.S. provides valuable data over vast area in a short timeabout resources, meteorology and environment leading tobetter resource management and accelerating nationaldevelopment.
The four organizations are engaged in remote sensingrelated activities besides several other central and state gov.and educational institutes:-1.ISRO 2.SAC3.NNRMS4.NRSA
Remote Sensing -Remote sensing is defined as the science which deals with obtaininginformation about objects on earth surface by analysis of data,received from a remote platform.Remote sensing can be either passive or active. Active systems have theirown source of energy whereas the passive systems depend upon the solarillumination or self emission for remote sensingPrinciples of Remote SensingDetection and discrimination of objects or surface features means detecting andrecording of radiant energy reflected or emitted by objects or surface material. Differentobjects return different amount and kind of energy in different bands of theelectromagnetic spectrum, incident upon it. This unique property depends on theproperty of material
Stages in Remote Sensing1. Emission of electromagnetic radiation, or EMR (sun/self-emission)2.Transmission of energy from the source to the surface ofthe earth, as well as absorption and scattering3. Interaction of EMR with the earths surface: reflection andemission4. Transmission of energy from the surface to the remotesensor5. Sensor data output6. Data transmission, processing and analysis
Aerial Remote SensingAerial photography is the most commonly used form of remote sensingand is widely used for topographic mapping, surveys for geological, soiland forestry mapping, engineering, town planning and environmentalsurveys on larger scale.
Remote Sensing SatellitesAs is known to us, many countries around the globe now have remotesensing satellite programs for land resources survey, environmentalimpact assessment, weather forecasting and ocean science studies. METSAT satellite programs for weather monitoring and LANDSATsatellite program for land resources surveys, both launched by the USAsince 1960 and 1972.
France has also started an ambitious SPOT satellite seriesprogram with the launching of SPOT-1 on 22nd February, 1986.Japan has launched Marine Observation Satellite (MOS-1) on 19thFeb. 1987.RADARSAT is Canadas first remote sensing satellite launchedduring 1990.European Space Agency (ESA) has launched Earth ResourcesSatellite (ERS-1) in 1991.India has launched a number of experimental remote sensingsatellites, Bhaskara-I (June, 1979) and Bhaskara-II (Nov., 1981),Indian Experimental Satellite
INSAT series of satellite, multipurpose Geostationary satelliteprogram, has among many sensors,(i) Very High Resolution Radiometer (VHRR) and (ii) Data CollectionSystem
Details of IRS Series of SatellitesIRS 1A 1988 1B 1991 1C 1995 1D 1997 P6 2003 cartosat1-2005 cartosat2-2007
Satellite Data Receiving StationThe Govt. of India authorized NRSA to set up a Satellite ReceivingStation to receive digital data from LANDSAT series of Satelliteslaunched by NASA/USA. This LANDSAT Receiving Station startedfunctioning since January, 1980 situated at Shadnagar, 55 km. southof Hyderabad.
Data Acquisition Systems In Remote Sensing two types 1. Image forming ( active sensor system photography) 2. non image forming (passive sensor system satellitedigital mode)
Imaging (Image forming) Image forming systems are againof two types - framing type and scanning type. In the framingtype, entire frame of image is acquired instantaneously in thebasic image unit e.g. in a frame camera used in photography. In scanning type, the information is acquired sequentiallyfrom the surface in bits of picture elements or pixels, point bypoint and line by line, which may be arranged after acquisition into a frame format
Non imaging type of sensors, are used to record aspectral quantity or a parameter as a function of time ordistance ( such as Gamma radiation, magnetic field,temperature measurement etc.) They are mostly usedfor ground observation and in study of atmosphere andmeteorology. These sensors do not form image and assuch, are not used in operational remote sensing butgive detailed information on spectral characteristics ofthe target .Such data is collected by sensor system insatellite and transmitted to earth, where it is receivedand recorded at Ground Station.
Characteristics of LISS-3/ LISS-4 LISS-3 Spectral Bands B2 0.52-0.59 μmB3 0.62-0.68 μm B4 0.77-0.86 μmB5 1.55-1.70 μm LIV B2 0.52-0.59 μm B3 0.62 - 0.68 B4 0.77 - 0.86spatial resolution L3 23.5 m for bands 2,3,4 70.5 m for band 5 L4 5.8 m (at nadir)Equivalent focal length (bands 2, 3, 4/ band 5) 347.5mm/301.2 mmSwath 141 km for bands 2,3,4 148 km for band 5 23.9 kmMS mode 70 km PAN mode
Satellite Data is recorded and products are available on following mediaSatellite data products are available in the following types of formats - High Density Digital Tape (HDDT) Quick Look Film Computer Compatible Tape(CCT), Digital Audio Tape(DAT) Compact Disc(CD-ROM) 70 mm film 240 mm Black and White film positive/negative in individual band. Black and White paper prints & enlargement in individual band 240 mm False Colour Composite (FCC) Film
TYPES OF SENSORS:-Optical Sensors used in remote sensing systems MSS TM HRV LISS I.II LISS III LISS IV PAN WIFS
Remote Sensing SensorsSensor is a device that gathers energy (EMR or other), converts itinto a signal and presents it in a form suitable for obtaininginformation about the target under investigation. These may beactive or passive depending on the source of energySensors used for remote sensing can be broadly classified asthose operating in Optical Infrared (OIR) region and thoseoperating in the microwave region. OIR and microwave sensorscan further be subdivided into passive and active
Active sensors use their own source ofenergy. Earth surface is illuminated through energy emittedby its own source, a part of its reflected by the surface in thedirection of the sensor is received to gather the information.Passive sensors receive solar electromagnetic energyreflected from the surface or energy emitted by the surfaceitself. These sensors do not have their own source of energyand can not be used at night time, except thermal sensors.Again, sensors (active or passive) could either be imaging,like camera, or Sensor which acquire images of the area andnon-imaging types like non-scanning radiometer oratmospheric sounders.
Sensors which operate in this region are : Aerial cameras : 0.38 um to 0.9 um Thermal scanners : 3 um to 5 um : 8 um to 16 um Multi spectral scanner : 0.3 um to 1.1 um Microwave wavelengths : 1mm to 1 meter (Sensors whichoperate in these wavelengths / frequencies are mostly active systems like RADAR )
Multispectral Scanner (MSS) used in Landsat seriessatellites i) Multispectral scanner (Optical Mechanical Scanner)onboard Landsat series of satellites of U.S.A. (L1, L2, L3, L4 & L5)gives line scan type imagery using an oscillating mirror tocontinuously scan the earth surface perpendicular to the spacecraftvelocity. Six lines are scanned simultaneously in each of the fourspectral bands for each mirror sweep. Spacecraft motionprovides the along-track progression of the scan lines. Radiationis sensed simultaneously by an array of six detectors each offour spectral bands from 0.5 to 1.1 micrometers. The detectors’outputs are sampled, encoded and formatted into continuousdigital data
(ii)Thematic Mapper (TM) used in Landsat series satellites Landsat 4 & 5 have onboard a new payload called "Thematic Mapper"with 7 spectral bands & ground resolution of 30 meters. This is in additionto the MSS payload which is identical to those carried onboard Landsat 1 & 2 and replaces RBV payload. TM is also an Optical Mechanical Scanner, similar to MSS; however, being a 2nd generation line scanning sensor, it ensures better performance characteristics in terms of (i)improved pointing accuracy and stability, (ii) high resolution, (iii) new and more number of spectral bands, (iv) 16 days repetitive coverage (v) high scanning efficiency using bi-directional scanning and (vi) increased quantization levels. For achieving the bi-directional scanning, a scanlinecorrector (SLC) is introduced between the telescope and focal plane. The SLC ensures parallel lines of scanning in the forward and reverse direction.
iii)High Resolution Visible (HRV) Imager used in SPOTSatelliteThe French SPOT-1 spacecraft carries two nominally identical HighResolution Visible (HRV) imagers, which can be operated independentlyor in various coupled modes. In contrast to the oscillating mirror designused in the Landsat imaging system, HRV cameras use Charge CoupledDevices (CCD) array as the sensing element for the first time in spaceenvironment. Each of the two cameras can be operated in eithermultispectral (20 m resolution) mode or panchromatic (10 m resolution)mode. The swath covered is 60 Km; and the cameras can be tilted offsetupto 27° on either side of Nadir. Thus any point within a width of 950 km.,centered on the satellite track can be observed by programmed cameracontrol. SPOT-1 has stereo coverage capability in orbit with tiltablecameras, which again provides stereo image pair al most similar to metriccamera air photo.
(iv)Linear Image Self Scanning (LISS) Cameraused in IRS-1A ,1BIndian Remote Sensing Satellite (IRS-1A) fully designed andfabricated by the Indian Space Research Organization(ISRO) was launched on March 17th, 1988 by Russianlauncher. It has four spectral bands in the range of 0.45 to0.86 μm (0.45 to 0.53 μm to 0.59 μm, 0.62 to 0.68 μm and0.77 to 0.86 μm) in the visible and near infrared range withtwo different spatial resolution of 72.5 m. and 36.25 meterfrom one no. of open LISS-1 and two nos. of LISS-2 camerasrespectively. It provides repetitive coverage after every 22days. Like all other LANDSAT/ SPOT missions which aredesigned for global coverage IRS is also in sun synchronous,polar orbit at about 900 km altitude and cover a width of 148km. on ground. It uses linear array detectors (CCD) likeSPOT.
v) Linear Imaging Self Scanning Camera-3 (LISS-3This camera is configured to provide imageries in threevisible bands as well as in short-wave infrared band. Theresolution and swath for visible bands are 23.5 m and 142km, respectively. The detector is a 6000 element CCDbased linear array with a pixel dimension of 10μm by 7 μm.The detector is placed at the focus of a refractive typeoptical system consisting of eight lens elements, whichprovides a focal length of 360 mm.The processing of the analogue output video signal issimilar to that of PAN. For this camera, a 7-bit digitization isused which gives an intensity variation of 128 levels.
Linear Imaging Self-Scanning Camera-4 (LISS-4)LISS-4 camera serves the dual purpose of acquiring 70 km swath,mono images giving continuity to the PAN camera of 1C/ 1D. In itsnormal mode it acquires 23 km swath 3 band multispectral imagery,which can be positioned anywhere in the 70 km coverage of Monomode. The enhanced dynamic range of 10 bits is intended to serve theworldwide requirement of radiometric ranges. The stereo capability of1C/ 1D is retained to provide the across track stereo to therequirement of the users.
Panchromatic camera (PAN)The PAN camera is configured to provide the imageries ofthe Earth in visible spectrum, in a panchromatic band (0.5-0.75 m) with a geometric resolution of greater than 10 mand a swath of 70 km. The camera uses an off-axisreflective type optics system consisting of three mirrors forproviding the required focal length. A 7μm pixel sized CCDis being used as the detector element. Using three lineararray charge-coupled detectors covers the total swath of 70km and each of these detectors covers aswath of about
The central detector is offset from the other two detectorsby a distance in focal plane that corresponds to 8.6 km onthe ground. The other two detectors cover swath of 24 kmeach adjacent to the central CCD. These two detectors arealigned with an accuracy of 30 arc sec-1. The overlap ofthe central swath with the side swaths is 600 m on theground. Each of the detectors provides four analogueoutputs, which are independently processed by videochains, converted to digital and providing a data handlingsystem for formatting. For a PAN data compatible with theexpected signal to noise ratio, a 6-bit digitization is usedwhich gives 64 radiometric gray levels.
Characteristics of PAN cameraGeometric resolution from altitude of 817 km 5.8 m Effective focal lengthfor optics 980 mm Swath 70 km Field-of-view for optics ±2.5o (acrosstrack) ±0.3o (along track) Spectral band 0.5-0.75 μm
viii) Wide Field Sensor (WiFS )This camera operates in two bands B3: 0.62 μm to 0.68 μm (Red) andB4: 0.77 μm to 0.86 μm (NIR). Each band uses a 2048 element CCDwith an element size of 13 μm by 13 μm. A wide-angle refractiveoptics system with 8-lens elements is used with a focal length ofabout 56 mm. This payload required to cover a ground swath of 770km with a resolution of 188 m. This ground swath with the selected817 km orbit can provide the required repetivity for the intendedapplication.
To cover the 770 km, two separate band assemblies areused for each band. Thus the entire swath in each band iscovered by two detectors. Each of the detectors covers halfof the swath. The signal processing chain in similar toLISS-3 wherein the analogue video signal is converted to 7bits and given to data handling system for formatting. Tablegives the characteristics of WiFS camera.
Advanced Wide Field Sensor (AWiFS) with a spatialresolution of 56 m providing a swath of 740 km. The camera operates inthe Visible, Near Infra Red and Short Wave Infra Red spectral bands.AWiFS is a unique camera having the capability to take the imagery ofthe world repeatedly every 5 days, in the fields of agriculture, land andwater resources management, and, disaster management.
LANDSAT Series of SatellitesNASA, with the co-operation of the U.S. Department of Interior, began aconceptual study of the feasibility of a series of Earth Resources TechnologySatellites (ERTS). ERTS-1 was launched on July 23, 1972. It represented thefirst unmanned satellite specifically designed to acquire data about earthresources on a systematic, repetitive, medium resolution, multispectral basis.It was primarily designed as an experimental system to test that feasibility ofcollecting earth resources data from unmanned satellites. Just prior to thelaunch of ERTS-B on January 22nd 1975, NASA officially renamed the ERTSprogramme as "LANDSAT" programme. All subsequent satellites in the seriescarried the Landsat designation. So far five Landsat satellites have beenlaunched successfully, Table highlights the characteristics of the Landsatseries satellites mission. There have been four different types of sensorsincluded in various combinations on these missions.
Multispectral Scanner (MSS) systems, Thematic Mapper (TM) andEnhanced Thematic Mapper (ETM).After more than two decades of success, the LANDSAT programrealized its first unsuccessful mission with the launch failure ofLandsat-6 on October 5, 1993. The sensor included on-board wasthe Enhanced Thematic Mapper (ETM). To provide continuity withLandsat -4 and -5 the ETM incorporated the same seven spectralbands and the same spatialresolutions as the TM. The ETMs majorimprovement over the TM was addition of an eighth panchromaticband operating in 0.50 to 0.90μm ranges a spatial resolution of 15m.Landsat-7 includes two sensors: the Enhanced Thematic Mapperplus (ETM+) and the High Resolution Multispectral Stereo Imager(HRMSI).
SPOT Series of SatelliteFrench Government in joint programme with Sweden and Belgiumundertook the development of Systeme Pour lObservation de la Terre(SPOT) program. Conceived and designed by the French CentreNational dEtudes Spatiales (CNES), SPOT has developed into a large-scale international programme with ground receiving stations and datadistribution outlets located in more than 30 countries. It is also the firstsystem to have pointable optics. This enables side-to-side off-nadirviewing capabilities, and it affords full scene stereoscopic imaging fromtwo different satellite tracks permitting coverage of the same area. SPOT-1 was retired from full-time services on December 31, 1990. The SPOT-2satellite was launched on January 21, 1990, and SPOT-3 was launchedon September 25, 1993 Spot 4 was launched on 26 March 1998. SPOT-1, -2 and -3 have identical orbits and sensor systems,
SPOT-4 includes the additional 20m-resolutionband in the mid-infrared portion of the spectrum (between 1.58 and 1.75μm).This band is intended to improve vegetation monitoring and mineraldiscriminating capabilities of the data. Furthermore, mixed 20m and 10mdata sets will be co-registered on-board instead of during ground processing.This will be accomplished by replacing the panchromatic band of SPOT-1, -2and -3 (0.49 to 0.73 μm) with red band from these systems (0.61 to 0.68μm). This band will be used to produce both 10m black and white imagesand 20m multispectral data. Another change in SPOT-4 is the addition of aseparate wide-field-of-view, sensor called the Vegetation SPOT-5 is the latest in Frances series of Earth observingsatellites, all of which were sent into orbit by Arianespace. Since thefirst SPOT satellite was launched in 1986, the SPOT system hassought to provide continuity of service and constantly improvedquality ofproducts for users. Spot 5 is the fifth satellite in the SPOT series,placed into orbit by an Ariane5 launcher in May 2002.
IRS Satellite SeriesThe Indian Space programme has the goal of harnessing spacetechnology for application in the areas of communications,broadcasting, meteorology and remote sensing. The importantmilestones crossed so far are Bhaskara-1 and 2 (1979) theexperimental satellites, which carried TV Cameras and MicrowaveRadiometers. The Indian Remote Sensing Satellite was the next logicalstep towards the National operational satellites that directly generatesresources information in a variety of application areas such as forestry,geology, agriculture and hydrology. IRS -1A/1B, carried Linear SelfScanning sensors LISS-I & LISS-II. IRS-P2 launched in October 1994on PSLV-D2 (an indigenous launch vehicle). IRS-1C, launched onDecember 28, 1995, which carried improved sensors like LISS-III,WiFS, PAN Camera, etc. Details of IRS series platforms are given inthe following section. IRS-P3 was launched into the sun synchronousorbit by another indigenous launch vehicle PSLV - D3 on 21.3.1996from Indian launching station Sriharikota (SHAR). IRS-1D waslaunched on 29 September 1997 and IRS-P4 was launched on 26 May1999.
Detatils of IRS Series SatellitesName Launch Sensors Types Band Spectral Resol Swath Revisit s range ution DAYS 72.5IRS 1988 L-I MS 4 36.25 148 221A L-II 741B 1991 L-I MS 4 72.5 22 L-II1C Dec95 WiFS MS 2 R,NIR 189 810 5 LIII MS 3+1 G,R,NIR 23.5 142 24 PAN PAN 1 SWIR1.55 70 148 -1.70 .50-.75 5.8 701D SEPT 774 24 97
Detatils of IRS Series SatellitesNam Launch Sensors Types Band Spectral Resol Swath Revisite s range ution DAYSIrs- oct200 AWiFS MS 3 G,R,NIR 56 740 5p6 3 PAN 1 SWIR1.5 LISS-III MS 3+1 5-1.70 23 141 24 GRNIR LISS-IV MS 3 SWIR 5.8 23MX GRNIR 70PAN
Detatils of IRS Series SatellitesName Launch Sensors Types Band Spectral Resol Swath Revisit s range ution DAYSIrs- oct2003 AWiFS MS 3 G,R,NIR 56 370, 5p6 PAN 1 SWIR1.55 740 -1.70 LISS-III MS 3+1 23 141 24 GRNIR SWIR LISS-IV MS 3 GRNIR 5.8 23MX 70PAN
Detatils of IRS Series SatellitesName Launch Sensors Types Band Spectral Resol Swath Revisit s range ution DAYSIrs- oct2003 AWiFS MS 3 G,R,NIR 56 370, 5p6 PAN 1 SWIR1.55 740 -1.70 LISS-III MS 3+1 23 141 24 GRNIR SWIR LISS-IV MS 3 GRNIR 5.8 23MX 70PAN
Details of IRS Series of Satellites Cartosat - 1 IRS-P6 (Resource -sat) IRS-P4 (Oceansat) IRS-1D IRS-1C IRS-1B IRS-1A
IRS-P4 (Oceansat-1)IRS-P4 carries an Ocean Colour Monitor (OCM) and a Multi-frequencyScanning Microwave Radiometer (MSMR), launched on May 26 1999.OCM has 8 narrow spectralbands operating in visible and near-infrared bands (402-885 nm) with aspatial resolution of 350 m and swath of 1500 kms. IRS P4 OCM thusprovides highest spatial resolution compared to any other contemporarysatellites in the international arena during this time frame. The MSMRwith its all weather capability is configured to have measurements at 4frequencies (6.6, 10.6, 18 & 26 GHZ) with an overall swath of 1500 km.The spatial resolution is 120, 80, 40 and 40 kms for the frequency bandsof 6.6, 10.6, 18 and 26 GHz. MSMR will also be in a way a unique sensoras no other passive microwave radiometer is operational in the civiliandomain today and will be useful for study of both physical oceanographicand meteorological parameters.
RESOURCESAT-1RESOURCESAT-1 was launched by ISROs Polar SatelliteLaunch Vehicle, PSLV-C5, from Satish Dhawan SpaceCentre-SHAR on October 17, 2003. RESOURCESAT-1carries three cameras on board:A multi-spectral high spatial resolution camera, namely,Linear Imaging Self Scanner-4 (LISS-4) providing a spatialresolution of 5.8 m and a swath of 23 km. It operates in theVisible and Near Infra Red spectral bands.(ii) A multi-spectral Linear Imaging Self Scanner-3 (LISS-3),which has a spatial resolution of 23 m and a swath of 141km. It operates in the Visible, Near Infra Red and ShortWave Infra Red spectral bands.
FCC Car NicobarIRS-P6-LISS-III BANDS 4 R 24 Meter DATE OF PASS- FEB.16,2005
IKONOSThe IKONOS-2 satellite was launched in September 1999and has been delivering commercial data since early2000. IKONOS is the first of the next generation of highspatial resolution satellites. IKONOS data records 4channels of multispectral data at 4-meter resolution andone panchromatic channel with 1-meter resolution. Thismeans that IKONOS is first commercial satellite to delivernear photographic quality imagery of anywhere in theworld from space.Radiometric Resolution: Data is collected as 11 bits perpixel (2048 gray tones). Timings of collecting / receivingIKONOS data and satellite orbit characteristics varyconsiderably depending on accuracy of product, extentand area.
Advantages and Limitations ofRemote SensingThe major advantages of remote sensing over the ground - basedmethods are:1.Synoptic view: Remote sensing process facilitates the study ofvarious features of earths surface in their spatial relation to eachother and helps to delineate the required features andphenomenon.2.Accessibility: Remote sensing process makes it possible togather information about the inaccessible area when it is notpossible to do ground survey like in mountainous areas or foreignlands.3.Time: Since information about a large area can be gatheredquickly, the techniques save time and efforts of human beings/ ormass.4.Multi-disciplinary applications: The data gathered by remotesensing process can be used by the users of different disciplineslike, geology, forestry land use etc.
Limitations of Remote Sensing Technology1. Since resolution of the data from LISS-III is 23.5 Mthe linear forest cover along roads, canals, bunds, rail of thewidth less than the resolution are generally not be recorded.2. young plantations and species having less chlorophyllcontents in their crown do not give proper reflectance and asa result are difficult to be interpreted correctly.3. considerable details on ground may be obscured in areashaving clouds and shadows. It is difficult to interpret suchareas without the help of collateral data.4. variation in spectral reflectance during leaf less periodposes problems in interpretation.5. gregarious occurrence of bushy vegetation, such aslantana, sugarcane etc, often poses problems in delineationof forest cover, as their reflectance is similar to that of treecanopy.
Appropriate season for aerial/satellite data acquisition in forestry 1. Humid/moist evergreen and semi-evergreen forests of western ghats and eastern ghats January-February 2. Humid and moist evergreen and semi-evergreen Andaman and Nicobar Islands February-March forests of north-east India and 3. Tropical moist deciduous forests of northern and central India December-January 4. Temperate evergreen forests of western Himalayas March-MayTemperate, sub-alpine, alpine evergreen, deciduous forests of Jammu 6. Arid and semi-arid dry deciduous and scrub forest October-December Mangrove for period 5. Jammu and Kashmir
BASIC COMPONENTS OF AN IDEAL REMOTE SENSINGSYSTEM1. Uniform energy source2. A non interfering atmosphere3. A series of unique energy- matter interactions at theearth’s surface4 A super sensor5. A real-time data processing and supply system6. Multiple data users
1.This source would provide energy over allwavelength at a constant, known ,high level of outputirrespective of time and place.2’This would be an atmosphere that would not modifythe energy from the source in any manner, whetherthat energy were on its way to the earth’s surface orcoming from it. Again, ideally, this would irrespectiveof wavelength, time, place and sensing altitudeinvolved.
3;These interactions would generate reflected or emitted signals that not only are selective with respect to wavelength, but also are known, invariant and unique to each and every earth surface feature type and subtype of interest.
4. This would be a sensor, highly sensitive to all wavelengths, yielding spatially detailed data on the absolute brightness form a scene as a function of wavelength throughout the spectrum. This super sensor would be simple and reliable. Require virtually no power or space and be accurate and economical to operate.
5.In this system, the instant the radiance wavelength response over a terrain element was generated, it would be transmitted to the ground, geometrically and radio metrically corrected as necessary and processed in to a readily interpretable format. Each data observation would be recognized as being unique to the particular terrain element form which came. This processing would be performed nearly instantaneously(real time) providing timely information.
6.These people would have knowledge of great depth both of their respective disciplines and of remote sensing data acquisition and analysis techniques. The same set of data would become various forms of information for different users, because of their wealth of knowledge about the particular earth resources being sensed. This information would be available to them faster, at less expense and over larger areas than information collected in any other manner, wise decision about how best to manage the earth resources under scrutiny and theses management decisions would be implemented.
ResolutionResolution is defined as the ability of the system torender the information at the smallest discretelyseparable quantity in terms of distance (spatial),wavelength band of EMR (spectral), time (temporal)and/or radiation quantity (radiometric).
—Spatial resolution the area on the earth’s surface thatcan be seen by a sensor as being separate from itssurroundings and is represented by a pixel.is the projection of a detector element or a slit onto theground. In other words scanners spatial resolution is theground segment sensed at any instant. It is also calledground resolution element (GRE). The spatial resolution atwhich data are acquired has two effects –the ability toidentify various features and quantify their extent
Spectral Resolution – the range of wavelength that satelliteimaging system can detect , it refers to the width and number of spectralbands. the narrow band the greater spectral resolution.describes the ability of the sensor to define fine wavelength intervals i.e.sampling the spatially segmented image in different spectral intervals,thereby allowing the spectral irradiance of the image to be determined.
Short wavelength Visible range blue band 0.45---0.52Green band 0.52---0.60 Red band 0.60---0.70 IR 0.70---3.0 Thermal 3---5 8---14Microwaves 1 mm ---1 m
Radiometric Resolutionis a measure of the sensor to differentiate the smallest change in thespectral reflectance/remittance between various targets. The radiometricresolution depends on the saturation radiance and the number ofquantization levels. Thus, a sensor whose saturation is set at 100%,reflectance with an 8 bit resolution will have a poor radiometric sensitivitycompared to a sensor whose saturation radiance is set at 20%reflectance and 7 bit digitization.
Temporal Resolutionis obtaining spatial and spectral data at certain time intervals. Temporalresolution is the capability of the satellite to image the exact same areaat the same viewing angle at different periods of time. The temporalresolution of a sensor depends on a variety of factors, including thesatellite/sensor capabilities, the swath overlap and latitude.
Suggested books1) Lillesand Thomas M. & Kiefer Ralph 2003 : RemoteSensing and Image Interpretation Third Edition John Villey2) Campbell John B. 1996 : Introduction to RemoteSensing, Taylor & Francis3) Floyd F. Sabins : Remote Sensing and Principles andImage Interpretation(1987)4) Manual of Remote Sensing IIIrd Edition : AmericanSociety of Photogrammtery and Remote Sensing 210, LittleFalls Street, Falls Church, Virginia-22046 USA.5) George Joseph. 1996: Imaging Sensors ; RemoteSensing Reviews, vol 13,Number 3-4.6) P.J. Curran, 1985. Physical aspects of Remote SensingLongman Group UR Ltd, England.
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