Quality Check of MOMS-2P Orthoimages of Semi-Arid Landscapes

Abstract

From 1996 until 1999 DLR operated the first 3-line along-track stereo scanner in space. This MOMS-2P camera was mounted onto the Russian space station Mir. It had its own navigation system consisting of GPS receiver and gyros. The orbit and attitude data derived from their measurements had already a very good relative accuracy in sub-pixel range. But absolute biases and drifts of exterior orientation and also some parameters of the interior orientation have to be estimated via bundle adjustment. Ground control points (GCP) have to be provided for this task. This always was a bottleneck of MOMS stereo evaluation. For large areas in Afghanistan, Jordan and Libya geocoded Thematic Mapper imagery was available. On one hand, these data have been used for automated GCP extraction via image matching. On the other hand, they are also used here to check the MOMS orthoimages produced by DLR’s MOMS stereo workstation software along with the digital elevation models which are a prerequisite of orthoimage generation. This check is done via automatic image matching. Mean and standard deviations of the shifts are found to be in sub-pixel range. The internal fit of the MOMS orthoimages of the off-nadir looking stereo channels of MOMS is also checked via image matching. The standard deviations of the shifts are in the order of 1/5th pixel which allows color composites of good radiometric quality and the use of the orthoimages in multispectral evaluation.