Analysis of Dem Generated Using Cartosat-1 Stereo Data over Mausanne Les Alpiles – Cartosat Scientific Appraisal Programme (csap Ts – 5)

The high-resolution Cartosat-1 stereo image data is expected to have significant impact in topographic mapping and watershed applications. The objective of the present investigation is to make an assessment of the potential of the Cartosat-1 data in topographic mapping and generation of DEMs in operational mode using COTS packages. The assessment is based on the entropy analysis of the fore/aft images, geometric quality of the fore/aft images (2-D perspective), generation of high-resolution Digital Elevation Model (DEM), Quality evaluation in different elevation strata, generation of ortho-image and associated accuracy assessment and application potential of the photogrammetric products for natural resources applications. The results of the study are part of phase I of C-SAP participation as a Co-Investigator (CoI) in the evaluation of CARTOSAT-1 data for test site TS5 (Mausanne-les-Alpilles, France). The inherent orientation accuracy of the Rational Polynomial Coefficients (RPC) models is established by comparison to the available ground truth. Ground control points are used to correct the RPC (bias correction and also higher order transformations) in order to assess the achievable accuracy for the generation of digital surface models (DSM). The evaluation of the geometric accuracy is based on the estimated sensor model parameters and on the residuals at the image control and check points using various configurations of control points. The DEM evaluation is based on the elevation differences at control points, the spatial distribution of the DEM differences and terrain gradients. The ortho-image is evaluated with respect to available reference data. The potential of thematic content for Cartosat-1 for mapping applications is tested based on the detection and identification of various topographic features. The average entropy of the image is around 5.6. The standard deviation, of the CartoSAT-1 DEM in comparison with high quality reference DEM, is of the order of 3.8m to 7.3m in different topographic conditions.