Stereo Evaluation of Alos/prism Data on Esa-ao Test Sites – First Dlr Results

DLR's Remote Sensing Technology Institute has more than 20 years of history in developing spaceborne stereo scanners (MEOSS, MOMS) and the corresponding stereo evaluation software systems. It takes part in the ESA/JAXA-AO Program to evaluate the performance and potential of the three-line stereo scanner PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) and the multispectral imaging sensor AVNIR-2 onboard the Japanese satellite ALOS as a principal investigator. German (Southeast Bavaria) and Spanish (Catalonia) test sites are proposed for which also PI evaluations for the SPOT-5 HRS Scientific Assessment Program (SAP) had been done already in 2003/04, and for the Indian CARTOSAT-1 (C-SAP) from 2006 onwards. In this paper, the process of direct georeferencing according to JAXA is shown and first results are presented. Ground control points (GCPs) are used to estimate boresight angles to improve the accuracy of the direct georeferencing. Rational polynomial coefficients (RPCs) are generated using DLR software. The comparison of a GCP-based approach and the rigorous approach reveals an oscillation of the satellite in the order of up to one pixel on the ground. The oscillations can not be compensated by an RPC-based approach. DEMs are generated and the coregistration of forward, nadir and backward view is examined. Thereby, problems in the processing of the interior orientation are revealed.