Image Processing, Accuracy Analysis

The Institute of Geodesy and Photogrammetry (IGP) is participating in the Cartosat-1 evaluation program, a common initiative of ISRO (India) and ISPRS. Within this program, various test sites with reference data have been established and Cartosat-1 images have been acquired over these sites. We have reported already about the Rome and Mausanne datasets in a former publication. Here, we report about our investigations at the Catalonia test site of ISRO. In addition, we evaluate the Cartosat-1 images acquired over the test site in Sakurajima, Japan. First, we report on image preprocessing for their improvement. Then, we report on RPC refinement and the 3D point positioning accuracy that can be achieved with the Rational Polynomial Coefficients (RPCs) sensor model. The orientation results include various options regarding sensor model and number and distribution of GCPs. The best results led to planimetric and height accuracies (RMSE) of about half a ground pixel size (2.5m) in both planimetry and height. Finally, we present the results of automatic DSM generation using our own SAT-PP program package. The results were checked both visually and were compared using the provided reference data (Catalonia DTM and Sakurajima DSM). While for the Catalonia test site the achieved height accuracy is about 3 m (sigma), confirming previous results we have reported in other test sites, for Sakurajima the results are significantly worse mainly due to the terrain relief