Global Digital Elevation Model from TanDEM-X and the Calibration/Validation with worldwide kinematic GPS-Tracks

Kurzfassung

In the first half of 2010 the second satellite of the system TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X) will be launched from Baikonur Cosmodrome, the first one – TerraSAR-X - is already working since more than two years. The TanDEM-X satellite mission will provide a digital elevation model (DEM) from the complete Earth. The relative height accuracy will be approx. 2m, the resolution on ground will be better than 12m. Four DLR institutes are responsible for the SAR payload, mission control, receiving stations, interferometric SAR (InSAR) processing, product generation and archiving and web interface. The scientific user community can use this web interface to submit their proposals and order DEMs for there test sites. The German company Infoterra will support commercial users. Four DEM products are planed: Intermediate DEM (2.5 years after launch) with less accuracy, final DEM (4 years after launch) with the required quality, FDEM with a higher ground resolution and HDEM with a better height quality. The paper will also give an overview about this DLR processing chain. These system- and product accuracy requirements will be guaranteed by different calibration and validation approaches. One important reference source especially for the validation are kinematic GPS tracks with accuracies better than 0.5m. Due to the fact that either local reference station or any regional reference station network is worldwide available Precise Point Positioning was selected as post processing method. In 2009 several world-wide tracks were measured with this method in Argentina/Chile, Brazil, North America, Central Europe, Northwest Africa, East-West coast track in southern Africa, Russia and Central Asia. Tracks in India and Saudi-Arabia are ordered and will be carried out in spring 2010. More than 50 000km were measured from different teams. This paper will present the organisation, requirements and experiences during the tracks, examples of the products (height-profiles) and first results of these kinematic GPS tracks. In summer 2008 the Commission 5 published the announcement "Kinematic GNSS for Evaluation of TanDEM-X Digital Elevation Model" to support the German satellite mission “TanDEM-X”.