Processing Strategies for Global Interferometric TanDEM-X DEM Generation

This paper summarizes the current status of the operational interferometric SAR (InSAR) processing of TanDEM-X data from three years of global acquisitions focusing on the methods implemented to provide raw DEM data which fulfills the high accuracy requirements of the final mosaicked TanDEM-X DEM. While most data is processed to DEMs which significantly exceed the performance requirements, the experience gained from processing far more than 300000 DEM scenes lead to optimizations in the processing chain to cope with data of extreme topography, low back-scatter, varying penetration depths, low interferometric coherence or temporal height changes. An important fact is that the SAR & InSAR processor uses the same initial approach for all incoming data and fully relies on the exploitation of the information in the SAR data itself without any external references, automatic quality control and re-processing with the support of other acquisitions triggered by feedback loops in case of quality issues. We present the detailed processing approach operationally used in bistatic SAR and InSAR processing to obtain an accurate DEM data set of globally homogenous high quality.