TerraSAR-X staring spotlight imaging: A chance to estimate absolute heights

The work presented exploits the long Synthetic Aperture Radar (SAR) of a single TerraSAR-X Staring Spotlight (ST) acquisition to derive absolute heights. Here, the slight azimuth defocussing effect due to height mismatch between true height and the height assumed in SAR focusing is analyzed. The impact is almost negligible for most of acquisition modes. In contrast, spaceborne modes with very long aperture, such as TerraSAR-X ST acquisition mode, present sensibility that can be used to retrieve absolute heights. The accuracy depends on incidence angle, orbit type and mainly on Signal to Clutter Ratio (SCR). A result over real data is presented to demonstrate that absolute heights can be retrieved with an accuracy of few meters using a single TerraSAR-X ST acquisition.