TanDEM-X DEM Calibration Concept and Height References

TanDEM-X is the first bistatic space borne SAR mission. It is formed by adding a second, almost identical spacecraft to TerraSAR-X and flying them in a closely controlled formation with typical distances between 250 m and 500 m. The primary goal of the mission is the derivation of a high-precision global Digital Elevation Model (DEM) according to HRTI level 3 quality. To achieve this accuracy, height references have to be applied in the calibration of the DEM, together with a least squares adjustment of adjacent interferograms. Content of this paper is the description of the general DEM calibration concept, which has a key incidence on mission aspects like the data acquisition plan, and the summary of the different analysis and research activities to validate it, with special stress on the height references selection.