Abstract
The three dimensional space is represented by Digital Elevation Models (DEMs) in a discrete form. DEM plays an important role in characterizing the topography and to derive the watershed boundaries thereby to study the landscape with in the watershed. Over a decade, DEMs from satellite imageries like ASTER, SRTM, IKONOS, Cartosat etc. are becoming popular with wide applications. However, issue of accuracy of DEMs generated from the satellite imageries is the major concern of remote sensing researcher’s. The main purpose of this study is to compare the accuracy of DEM generated from two different satellite sources, 1) Optical based sensory satellite data – Cartosat-DEM. 2) Microwave based sensory satellite data – SRTM-DEM. The study was conducted over Southpennar watershed which has gradually undulating topography. The comparative study was done under two categories; they are through elevation data and terrain derivatives. The study reveals that in gradually undulating terrain, elevation values of Cartosat-DEM are lower than SRTM-DEM. whereas the stream parameter values of Cartosat-DEM are higher than SRTM-DEM. In visual analysis the contours obtained from Cartosat-DEM and SRTM-DEM aligns with each other irrespective of the resolution.
Highlights
The most common and the simplest form of terrain representation in 3D are the Digital ElevationModels (DEMs)
The comparative study was done under two categories; they are through elevation data and terrain derivatives
The study reveals that in gradually undulating terrain, elevation values of Cartosat-Digital ElevationModels (DEMs) are lower than Shuttle Radar Topography Mission (SRTM)-DEM. whereas the stream parameter values of Cartosat-DEM are higher than SRTM-DEM
Summary
The most common and the simplest form of terrain representation in 3D are the Digital Elevation. The satellite based DEMs can be assessed by comparing the elevation data generated from them with elevation data obtained from topographic maps. The assessments can be done by comparing DEM’s elevation data with the elevation data’s obtained from Global Positioning. Systems (GPS) or with Differential Global Positioning Systems (DGPS). It’s very expensive to procure DGPS data’s. The accuracy of DEMs produced from satellite is found to be ±5 and ±20 m. RMSE (Root Mean Square Error) [1]. From past few years many researchers have done a series of local and global assessments of these elevation products. Evaluation of ASTER GDEM of 20 sites in countries was conducted.
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