Remote Sensing

Types of Remote Sensing In respect to the type of Energy Resources 

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Passive Remote Sensing: Makes use of sensors that detect the reflected or emitted electro-magnetic radiation from natural sources. Active Remote Sensing: Makes use of sensors that detect reflected responses from objects that are irradiated from artificially-generated energy sources, such as radar.

In respect to Wavelength Regions Remote Sensing is classified into three types in respect to the wavelength regions 

Visible and Reflective Infrared Remote Sensing

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Thermal Infrared Remote Sensing Microwave Remote Sensing

Bands Used in Remote Sensing Emission of EMR (Electro-Magnetic Radiation) from gases is due to atoms and molecules in the gas. Atoms consist of a positively charged nucleus surrounded by orbiting electrons, which have discrete energy states. Transition of electrons from one energy state to the other leads to emission of radiation at discrete wavelengths. The resulting spectrum is called line spectrum. Molecules possess rotational and vibration energy states.Transition between which leads to emission of radiation in a band spectrum. The wavelengths, which are emitted by atoms/molecules, are also the ones, which are absorbed by them. Emission from solids and liquids occurs when they are heated and results in a continuous spectrum. This is called thermal emission and it is an important source of EMR from the viewpoint of remote sensing. The Electro-Magnetic Radiation (EMR), which is reflected or emitted from an object, is the usual source of Remote Sensing data. However, any medium, such as gravity or magnetic fields, can be used in remote sensing. Remote Sensing Technology makes use of the wide range ElectroMagnetic Spectrum (EMS) from a very short wave "Gamma Ray" to a very long 'Radio Wave'. Wavelength regions of electro-magnetic radiation have different names ranging from Gamma ray, X-ray, Ultraviolet (UV), Visible light, Infrared (IR) to Radio Wave, in order from the shorter wavelengths. The optical wavelength region, an important region for remote sensing applications, is further subdivided as follows:

Name Wavelength (mm) Optical wavelength 0.30-15.0 Reflective portion 0.38-3.00 (i) Visible 0.38-0.72 (ii) Near IR 0.72-1.30 (iii) Middle IR 1.30-3.00 Far IR (Thermal, Emissive) 7.00-15.0 Microwave region (1mm to 1m) is another portion of EM spectrum that is frequently used to gather valuable remote sensing information. Spectral Characteristics vis-à-vis different systems The sunlight transmission through the atmosphere is effected by absorption and scattering of atmospheric molecules and aerosols. This reduction of the sunlight's intensity s called extinction. One cannot select the sensors to be used in any given remotesensing task arbitrarily; one must instead consider

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the available spectral sensitivity of the sensors, the presence or absence of atmospheric windows in the spectral range(s) in which one wishes to sense, and the source, magnitude, and spectral composition of the energy availabe in these ranges. Ultimately, however, the choice of spectral range of the sensor must be based on the manner in which the energy interacts with the features under investigation.

Energy Interactions, Spectral Reflectance and Color Readability in Satellite Imagery All matter is composed of atoms and molecules with particular compositions. Therefore, matter will emit or absorb electro-magnetic radiation on a particular wavelength with respect to the inner state. All matter reflects, absorbs, penetrates and emits Electro-magnetic radiation in a unique way. Electro-magnetic radiation through the atmosphere to and from matters on the earth's surface are reflected, scattered, diffracted, refracted, absorbed, transmitted and dispersed. For example, the reason why a leaf looks green is that the chlorophyll absorbs blue and red spectra and reflects the green. The unique characteristics of matter are called spectral characteristics. Energy Interactions When electro-magnetic energy is incident on any given earth surface feature, three fundamental energy interactions with the feature are possible. See Fig. 2

Fig 2: Basic interactions between electromagnetic energy and an

earth surface feature Spectral Reflectance & Color Readability Two points about the above given relationship (expressed in the form of equation) should be noted. 

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The proportions of energy reflected, absorbed, and transmitted will vary for different earth features, depending upon their material type and conditions. These differences permit us to distinguish different features on an image. The wavelength dependency means that, even within a given feature type, the proportion of reflected, absorbed, and transmitted energy will vary at different wavelengths.

Thus, two features may be distinguishable in one spectral range and be very different on another wavelength brand. Within the visible portion of the spectrum, these spectral variations result in the visual effect called COLOUR. For example we call blue objects 'blue' when they reflect highly in the 'green' spectral region, and so on. Thus the eye uses spectral variations in the magnitude of reflected energy to discriminate between various objects. A graph of the spectral reflectance of an object as a function of wavelength is called a spectral reflectance curve. The lines in this figure 3 represent average reflectance curves compiled by measuring large sample features. It should be noted how distinctive the curves are for each feature. In general, the configuration of these curves is an indicator of the type and condition of the features to which they apply. Although the reflectance of individual features will vary considerably above and below the average, these curves demonstrate some fundamental points concerning spectral reflectance.

Fig 3: Special Reflectance Curve of common object Band Wavelength (mm) 1 0.45-0.52

2

0.52-0.59

3

0.62-0.68

4

0.77-0.86

Principal applications Sensitive to sedimentation, deciduous/ coniferous forest cover discrimination, soil vegetation differentiation Green reflectance by healthy vegetation, vegetation vigor, rock-soil discrimination, turbidity and bathymetry in shallow waters Sensitive to chlorophyll absorption: plant species discrimination, differentiation of soil and geological boundary Sensitive to green biomass and moisture in vegetation, land and water contrast, landform/ geomorphic studies.

Color Discrimination based on Wavelengths of Spectral Reflectance’s. ( IRS-IA/IB LISS I and LISSII*) Platforms The vehicles or carriers for remote sensors are called the platforms. Typical platforms are satellites and aircraft, but they can also include radio-controlled aero planes, balloons kits for low altitude remote sensing, as well as ladder trucks or 'cherry pickers' for ground investigations. The key factor for the selection of a platform is the

altitude that determines the ground resolution and which is also dependent on the instantaneous field of view (IFOV) of the sensor on board the platform. Sensors  

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Active Sensors: Detect the reflected or emitted electromagnetic radiation from natural sources. Passive Sensors: Detect reflected responses from objects that are irradiated from artificially-generated energy sources such as radar. Resolution In general resolution is defined as the ability of an entire remote-sensing system to render a sharply defined image. Spectral Resolution: Spectral Resolution of a remote sensing instrument (sensor) is determined by the band-widths of the Electro-magnetic radiation. Radiometric Resolution: It is determined by the number of discrete levels into which signals may be divided. Spatial Resolution: It is determined in terms of the geometric properties of the imaging system. Temporal Resolution: Is related to the repetitive coverage of the ground by the remote-sensing system.

Remote Sensing Satellites A satellite with remote sensors to observe the earth is called a remote-sensing satellite, or earth observation satellite. RemoteSensing Satellites are characterized by their altitude, orbit and sensor. IRS (Indian Remote Sensing Satellite) India has launched several satellite includes IRS 1A, IRS 1B, IRS 1C, IRS 1D, IRS P 2,IRS P 3, IRS P 4 for different applications. Landsat It is established at an altitude of 700 kms is a polar orbit and is used mainly for land area observation.

Other remote sensing satellite series in operations are: SPOT, MOS, JERS, ESR, RADARSAT, IKONOS etc. Basic Concept of LiDAR Mapping The accuracy and functionality of many GIS projects rely to a large extent on the accuracy of topographic data and the speed with which it can be collected. The recently emerged technique of airborne altimetric LiDAR has gained considerable acceptance in both scientific and commercial communities as a tool for topographic measurement. The LiDAR instrument transmits the laser pulses while scanning a part of terrain, usually centered on and co-linear with, the flight path of the aircraft in which the instrument is mounted. The round trip travel times of the laser pulses from the aircraft to the ground are measured with a precise interval timer. The time intervals are converted into range measurements, i.e. the distance of LiDAR instrument from the ground point struck by the laser pulse, employing the velocity of light. The position of aircraft at the instance of firing the pulse is determined by Differential Global Positioning System (DGPS). During the movement of aircraft experience lot of distortions in altitude, lateral movements so on but these warps are taken care by the instrument to yield accurate coordinates of points on the surface of the terrain. Laser mappers acquire digital elevation data with accuracies equivalent to those of GPS, but thousands times faster. Basics of Digital Image Processing Remote sensing images are recorded in digital form and then processed by the computers to produce images for interpretation purposes. Images are available in two forms - photographic film form and digital form. Variations in the scene characteristics are represented as variations in brightness on photographic films. A particular part of scene reflecting more energy will appear bright while a different part of the same scene that reflecting less energy will appear black.

Digital image consists of discrete picture elements called pixels. Associated with each pixel is a number represented as DN (Digital Number), that depicts the average radiance of relatively small area within a scene. The size of this area effects the reproduction of details within the scene. As the pixel size is reduced more scene detail is preserved in digital representation. Digital image processing is a collection of techniques for the manipulation of digital images by computers. Digital image processing encompasses the operations such as noise removal, geometric and radiometric corrections, enhancement of images, information extraction and image data manipulation and management. Image Processing Methods Image processing methods may be grouped into three functional categories: Geometric and Radiometric Corrections The correction of errors, noise and geometric distortions introduced during scanning, recording and playback operations. However, the data supplied by NRSA-Hyderabad is corrected for these errors. Hence, we are restricted to the enhancement techniques and information extraction. Image Enhancement •

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Linear Contrast Enhancement: Very few scenes have a brightness range that utilizes the full sensitivity range of the detectors. To produce an image with the optimum contrast ratio, the entire brightness range of the display medium, should be utilized. In linear contrast we have to assign the low end as 0 (zero) and the high end as 1(One) and the other values in between are linearly stretched. The linear stretch improves the contrast for most of the original brightness values. Spatial Filtering: Spatial Filtering is a pixel by pixel transformation of an image, which depends on the grey-level of

the pixels concerned as well as the greylevel of the neighborhood pixels. It is a procedure in which greylevel of a pixel is altered according to its relationship with respect to the greylevel of the neighboring pixels. Information Extraction In the case of information extraction processes the computer makes decisions to identify and extract specific pieces of information.

Indian Remote Sensing Satellite Cartosat-1: Technical features and data products India has a lead in the civilian remote sensing field in the world not only in terms of realization and launching of complex satellites with high, medium and coarse resolution cameras, but also in the application areas as well. In order to maintain this lead and also provide continuity of data to global users, Cartosat-1 with two improved fore and aft PAN cameras with better than 2.5 m. spatial resolution is planned to be realized for launch by middle of 2003. This paper briefly presents the technical elements and the planned data products of the Cartosat-1 spacecraft. Cartosat-1 Spacecraft Technical Elements: The spacecraft is configured with the Panchromatic cameras which are mounted such that one camera is looking at +26 deg. w.r.t. nadir and the other at -5 deg. w.r.t. nadir along the track. These two cameras combinedly provide stereoscopic image pairs in the same pass. Also the whole spacecraft is steerable across track to provide wider coverage in a shorter period. A brief description of the payload and the other mainframe elements are given in the subsequent sections.

Remote Sensing Payloads: The payload performs the function of imaging an area along the track and transmits the data for ground processing. Each Panchromatic camera consists of three 3 mirror off-axis all reflective telescope with primary, secondary and tertiary mirrors. These mirrors are made from special zerodur glass blanks and are light weighted to about 60%. These mirrors are polished to an accuracy of l/80 and are coated with enhanced AlO2 coating. The mirrors are mounted to the Electrooptical module using iso-static mounts, so that the distortion on the light weighted mirrors are very minimum. In order to meet the high resolution and the swath requirement 12K, 7 micron linear array CCD is planned to be used as a detector. The CCD processing electronics will be using high speed devices to meet the high data rate requirements. Some of the important specifications of the payload are given in Table 2.1

T able 2.1: Payload Specifications S.No . Parameter Name

SpecificationFore (+26 deg.) Aft (-5 deg)

1.

Spatial Resolution:GIFOV (m) 2.5 x 2.78 2.22 x 2.23 (Across-track x alongtrack)

2.

Spectral Resolution a) No. of Bands b) Bandwidth

1 Panchromatic 500 nm to 850 nm

3.

Radiometric Resolution a) Saturation Radiance b) Quantisation c) SNR

55mw/cm*cm/str/micron 10 bits 345 at Saturation Radiance

4.

Swath (km) (Stereo) Fore + Aft Combined (Mono) Km.

30 26.855

5.

CCD Parameters: a) No. of Detectors \ 12000 per camera elements 7 x 7 microns b) Detector Element 35 microns staggered Size c) Odd-Even Spacing

6.

Optics a) No. of Mirrors b) Effective Focal Length (mm) c) F-Number d) Field of View (degrees)

3 1980 F/4.5 +/- 1.08

7.

Integration Time (ms)

0.336

8.

MTF a) Across track b) Along track

20 23

9.

Onboard Calibration

Relative, using LEDs

10

. Data Rate

105 Mb/s

11.

Data Compression: JPEG a) Algorithm Max.3.2 b) Compression Ratio

12

Nominal B/H Ratio for 0.62 Stereo

13.

P/L Operating Temp. Range

20 +/- 1 degree C.

2. Orbit Considerations: A polar sun synchronous orbit of altitude 618 Kms. with an inclination of 97.87 deg. and an equatorial cross-over local time of 10:30 hours and the descending node has been selected based on various considerations. The sun-synchronous orbit provides the imagery collection under near-constant illumination conditions throughout the life and repetitive coverage of the same area in a specified interval. In order to revisit the same place at a more frequent interval than the repetitive cycle, an off-nadir viewing capability is provided. Using this facility any area which could not be imaged on a given day due to cloud cover, etc. may be imaged on another day. The typical revisit cycle is 5 days with the off-nadir cross-track steering facility. Important orbital specifications are given in Table 2.2. Table 2.2 Orbit Specifications S.No. Orbit Characteristic

Specification

1.

617.99

Nominal Altitude (km)

2.

Number of orbits per day 15

3.

Orbital Repetivity Cycle (No. of days)

116

4.

Nominal Wait Time to Acquire Adj.Path

11 days

5.

Max. Wait Time for Revisit

5

6.

Node for P/L Operations

Descending Node.

7.

Local Time for Equatorial 10:30 AM Crossing

8.

Orbital parameters a) Semi-major axis b) Eccentricity c) Inclination

6996.128 km. 0.001 97.87 deg.

2.Spacecraft main frame systems:

The spacecraft bus has to support the payload systems in terms of structure, thermal control, power supply, data compression, data formatting and encryption and transmissions, data storage, TTC, etc. The spacecraft will be equipped with precision Attitude and Orbit Control system along with attitude sensors and propulsion systems. A brief description of various main frame systems is given below.

Cartosat-1 Platform Configuration: The spacecraft will be 3-axis body stabilized by using 4 high torque Reaction Wheels mounted in a tetrahedral arrangement. The power generation capacity will be about 1100 watts at the end of life, to meet the global operation of the payloads. The overall spacecraft size will be about 2.4 m. x 2.7 m. and will weigh about 1450 Kg. The orbit a.

configuration of the CARTOSAT-1 spacecraft is given in Fig.2.2.

Fig 2.2 On-orbit configuration of cartosat-1 spacecraft

Attitude and Orbit Control System (AOCS): In order to meet the stringent requirements of the high resolution payloads, it is necessary to have a precision Attitude Control System to provide a stable platform. Also in order to provide the required swath, overlap and to provide time invariant data and revisit requirements, the orbit control will be carried out periodically. Some of the important specifications of the AOCS are given below b.

Attitude Pointing Accuracy (deg.) of all axes: 0.05 Attitude drift (deg/sec) : 5 x 10 - 5 Attitude determination accuracy (deg) : 0.01 Ground location accuracy (m) : < 220 The drift rate determines the image internal distortion figures, whereas the jitter affects the resolution parameters. The AOCS will meet the stringent attitude pointing accuracy and the stability using a wide area star sensor in Attitude

Control loop and better control algorithms and using dynamic friction compensation technique for the ball bearing Reaction Wheels. AOCS will be configured with MIL-STD 31750 processor and with ASIC and HMCs. various sensors like, earth sensors, star sensors, precision yaw sensors and precision digital sun-sensors will be used to control and determine the attitude of the spacecraft precisely. Hydrazine mono-propellant Reaction Control System with 4 Nos. of 11 Newton Thrusters and 8 Nos.of 1 Newton Thrusters will be used for backup control and for momentum dumping purposes. About 131 Kg. of RCS fuels will be planned to provide a minimum mission life of 5 years. Earth Rotation Compensation: In the case of along track stereo data acquisition, same scene on the surface of earth is imaged with a time difference. The time difference is a function of the difference in forward and backward look angles chosen from other criteria and can be anywhere between 50 and 100 seconds. Major change in imaging conditions during this time period is due to rotation of earth. At the equator the effect of earth rotation is to shift the imaged point to the East by a distance of approximately 463.3 m for every one second. Thus during 50 seconds the shift is of the order of 23.2 Km. At 25 degrees latitude, the shift is 20.09 Km. If the separation in time between forward and backward imaging is more than 65 seconds then no overlap between them is present in case of zero yaw angle. In order to ensure stereo imaging it is necessary that the aft camera views the earth's surface in such a way as to image the shifted point. This condition can be achieved by a continuous yaw manoevring . For any given latitude, it can also be achieved by mounting the payloads at appropriate yaw angle with respect to each other. A combination of fixed mounting, catering to stereo acquisition requirements for Indian latitudes and a yaw manoeuvring for other regions with minimum power consumption shall be adopted. Alternatively the spacecraft is manoeuvred such that the image strips will fall side by side c.

so that wider swath images are obtained by the two cameras. Data Handling System: The realisation of high precision cameras calls for the development of very high speed precision electronic systems, and requires gain bandwidth of low noise analog system in the range of a few GHz. Due to small IFOV, the signal amplitudes are also expected to be very low. The detectors also require ultra low noise, biases and high frequency read out clocks. The data rate requirement for 2.5 m. resolution system is about 340 MBPS for a typical 10 bit quanitisation. This high bit rate Data is compressed by 3.2 : 1 by JPEG Compression technique to bring down the data rate to 105 m compatible for X-Band Data transmission system. The payload data is transmitted in two X-band carriers one for each PAN camera, after QPSK modulation to the Data Reception Station (DRS). A spherical Phased Array Antenna with steerable beam to the required DRS is used to transmit the payload data. A solid state recorder with 120 GB capacity to store about 9.5 min. of payload data and playback to the required ground station is also planned for the global operation of the payloads d.

Cartographic Data Products: The overview of the Cartosat-1 Data Products generation facility is given in fig.3.1.

The main constituents of this facility are, 1) Data Archival and Quicklook Browser (DAQLB) Systems, 2) Data Processing System (DPS) and 3) Cartosat Data Centre (CDC). The CDC interfaces with the Cartosat user community in getting the user requirements and processes the archived or acquired data, making use of the submodules like Stereo Strip Triangulation (SST), the Ground Control Point Library (GCPL) and the Data Products and Services modules. The stereo strip triangulation subsystem takes the primary GCPs and the DLI as input and generates (1) Triangulated Control Points (TCP), (2) Coarse DEM and (3) Updated orientation parameters. The TCPs and coarse DEMs and the IMS work order are the inputs for data products generation subsystem along with DLTs for generation of Data Products operationally. Various types of Data products planned using Cartosat images are (1) Image Data Products, (2) Image Map Data Products and (3) DEM Data products. Various aspects of the Data products (and various resource generation like coarse DEM generation and Triangulated Control Point (TCP) generations are briefly given below. 1. Image Data Products:

The levels of Image Data Products defined on the basis of their indented end use with attended impact on accuracy and turnaround time.Different types of image data products meeting the targeted user needs are generated based on the spacecraft operational modes like stereo mode or mono mode and the

orbit and attitude determination modes. Different types of products meeting the station specific user needs over the entire globe coverage is also planned for different earth stations and onboard SSR modes of data acquisition. 2.Image Map Data Products (IMDP):

IMDP containing co-registered ortho corrected Cartosat-PAN raster images with one or more layers of cartographic vector information (available apriori or derived from Cartosat image) including a layer containing ASCII text strings as labels of vector elements, with necessary additional ancillary information shall be generated and supplied to the users. The following types of products are planned. a. 2-D Satellite Image Map Products in conventional map projection or with user-defined projection parameters. b. 2.5-D Satellite Image Map Products, representing the terrain elevation for one or more fixed, standard perspective view angles possibly with artificially exaggerated scaling effects incorporated to show the terrain relief. c. 3-D Satellite Image Map Products, optionally including the 3-D viewing software as a part of the product. All the types of image map products are corrected CartosatPAN images, either on stand alone basis or desirably fused with available multi-spectral images with comparable spatial resolution as the base raster image. 2.DEM Data Products:

The following types of DEM Data Products are planned to be generated. Type I: As computed originally:

1. As randomly distributed point heights as computed originally. 2. As triangulated Irregular Network (TIN) retaining all the originally computed points, as they are. 3. As progressively sampled rectangular grids, retaining all the originally computed points, as they are Type II: As completed originally and incorporating break-lines: 1. As a set of irregular point heights and break lines showing the surface discontinuities 2. As a TIN model retaining all the originally computed points as they are; and in addition incorporating break lines, either as part of the TIN edges (referred as soft break lines) or as add-on specification (referred as hard break lines) indicating abrupt surface changes. 3. As progressively sampled rectangular grids, retaining all the originally computed points, as they are plus the break lines manually identified. Type III: As interpolated, mostly regular 1. As a rectangular grid, generated by a suitable interpolation algorithm from the initial set of irregular points and break lines. 2. As contours, connecting points of equal height at varying intervals. 3. As a set of parallel vertical profiles, in any user desired direction.

2.Coarse DEM Generation (CDG):

It is necessary to carryout scene based processing for mono mode data acquisition for either fore or aft camera towards generating level 1 or level 2 products with minimum internal distortion as per

the quality requirements. However, since the Cartosat cameras are mounted onboard the spacecraft in non-nadir viewing configuration, this can be achieved by carrying out terrain corrections apart from the system level corrections. Hence it is necessary to have DEM for all coverage for this purpose. Cartosat1 being a stereo mission, allows for building such database on a pass or a pass segment basis. 5.Triangulated Control Points Library Generation (TCG):

To enable scene based precision processing for mono or stereo mode data acquisition, a second generation control points call TCP of approximately about 10 points in each standard scene (~30 x 30 KM) covering the entire region are generated and maintained as a data base and are used during products generation. 5.Data Product Accuracy:

The accuracy of various products planned to be generated depends upon the accuracies of the SST parameters, TCDS, Coarse DEM, Precision DEMs etc. It is planned to have SST parameters within an accuracy of 3.3 M (1σ) based on GCP coordinate of 3M in planimetry and height accuracies. The accuracy of TCP derived from the SST processing is about 4M (1σ ) and based on conjugate point identification accuracy of about 2.5 m (3σ). The Coarse DEM will have planimetric error of about 3.1 (1 σ ) equivalent to the SST parameter error and the height is depending on the planimetric error and N/H ratio. The final DEM is generated after incorporating break lines / break points through manual / semi automatic methods with an RSS error of 2.5 m (1σ) in planimetry and 3.1 m in height. The error budget calculated for scene level processing is for a scene size of about 30 KM x 30 KM and less and is of the order of 0.25 m (3σ). The location accuracy of various data products are given below:

a. b. c.

For system level correction (level 1) (3σ) : 220 m With GCP (level 2) (3σ ) : 18.7 m With terrain (Coarse DEM) corrected (level 3A) (3σ): 21

m d. e.

With final DEM (LEVEL 3B) (3σ) : 18.7 m With precision GCP & precision DEM (level 3C) : 6.4 m*

(3σ) *This product uses precise GCPS and precision DEM with incorporation of break lines and break points. Hence the internal distortion will be better than 1 pixel (<2.5 m). The level 2, 3A and 3B products are standard products whereas the level 3C products are always value added products whose turnaround time depends on the availability of the images and ancillary information (GCPs) etc. 5.Data Product Size, Scale and Datum:

Various Products size is (1) based on modes of operation vise mono, stereo or wide swath mode as defined by path/row or Lat./Long. referencing schemes, (2) User defined rectangular areas aligned to true North of minimum size 2.5 KM x 2.5 KM and area equivalent to the maximum scene size 30 KM x 30 KM, (3) User defined polygonal areas of minimum size 2.5 KM x 2.5 KM and (4) Standard Map sheet extents for 1:25,000 and 1:50,000 scales. All levels of products are oriented towards true North and standard map projection as applicable for different user needs across the globe. Also the horizontal and vertical datum of the geo corrected products is referenced to appropriate datum as applicable for different needs across the globe. 5.Data Products Format:

The digital products are generated and supplied in any conventional format like CEOS super structure and IRS fast formats with Cartosat specific changes, along with all necessary ancillary parameters addressing all possible data utilization needs of Cartosat-1 PAN data, for various levels of products for different

application along with GIS and CAD and 3D software packages. The formats currently used in different GIS and CAD software packages such as Multi-Resolution Seamless Image Database (MRSID) universal data formats and Geotiff are suitably modified for Cartosat-I specific features.

Conclusion: Several countries, apart from India have embarked on space based remote sensing. A number of remote sensing satellites launched in the last decade such as Landsat, SPOT, ERS, and IRS series have shown very encouraging results for variety of Land and Marine applications. They also have aggressive plans for advancing the remote sensing technologies for different applications in future. In India ISRO has taken a lead in Land Resource application Satellites and has evolved plans to sustain and advance in all areas of earth resource applications. Basically, Indian Space Programme in the Remote Sensing area plans for improved mission in the area of (a) Cartographic and Mapping Applications (b) Land and Agricultural applications (3) Oceanographic applications, (4) Atmospheric Applications and (5) Climatic applications. Although globally there have been many satellite system being operational and planned with higher resolutions to meet the ultimate information requirements of the user community for geo-engineering applications and cadastral requirements, the launch of Cartosat-1 is expected to meet the immediate demands for terrain visualisation, updation of topographic maps, generation of National topographic data base and other utilities planning.