Page 1 of 3 Next  Amitabh Satellite Photogrammetry and Digital Cartography Divison Signal and Image Processing Group Space Applications Centre Ahmedabad-380015 amitabh@ipdpg.gov.in B Gopala Krishna Satellite Photogrammetry and Digital Cartography Divison Signal and Image Processing Group Space Applications Centre Ahmedabad-380015 bgk@ipdpg.gov.in PK Srivastava Satellite Photogrammetry and Digital Cartography Divison Signal and Image Processing Group Space Applications Centre Ahmedabad-380015 amitabh@ipdpg.gov.in 1. Introduction This paper presents an assessment, from a user point of view, of the characteristics of the freely available Global DEMs in Indian context. The available global DEMs are SRTM and GTOPO. The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. SRTM is an international project spearheaded by the National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and Space Administration (NASA). The present study focuses on accuracy evaluation of Global DEMs generated from various methods and freely available in the public domain. In this study, DEM generated through automatic method from stereo pair of High resolution images is compared with respect to SRTM and GTOPO DEMs. The main objective of this study is to compare the absolute and relative differences between the available global DEMs of the area using field based Ground Control (GCPS) as a base line. 2. Data Sets Used 2.1.1. SRTM DEM The SRTM is a joint project of NASA and the U.S. National Imagery and Mapping Agency (NIMA). Using C-band Spaceborne Imaging RADAR (SIR-C) and X-band Synthetic Aperture RADAR (X-SAR), SRTM collected data during a shuttle flight in February 2000. The SIR-C/X-SAR is a multifrequency, multipolarization imaging RADAR system, complemented by additional antennas located at the end of a 60 m long mast which deployed from the shuttle after reaching orbit. This configuration produced single-pass interferometry and during the mission SRTM imaged all of the Earth’s land surface between 60 degrees north and 50 degrees south [2]. In 2003, the National Aeronautics and Space Administration (NASA) released the Shuttle Radar Topography Mission (SRTM) dataset for some regions, with 3 arc-second resolution for the globe, and 1 arc-second for the United States. The vertical units represent elevation in meters above mean sea level. All elevations are in meters referenced to the WGS84EGM96 Geoid [5] and the horizontally geo-referenced to the WGS84 ellipsoid using a geographic projection. Projection: Geographic Ellipsoid: WGS 84 Datum: WGS 84 In this study the DEM has been cropped from the entire India mosaic SRTM DEM for the same area (corner coordinates) as specified in table 1 for Hyderabad, Bangalore and Alwar area. Some missing areas are masked as values were not available in the SRTM DEM. Table-1. Extent of Datasets used for Study
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