Analyzing the topographic influence for the PS-INSAR processing in the Three Gorges region

Persistent Scatterer Interferometry (PS-InSAR) is applied to derive displacement information with millimetric precision. Analyzing stable persistent scatterers from a large stack of SAR images,helps to overcome the geometrical and temporal decorrelation, which occur when using differential interferometry. The removal of the topographic phase with an external DEM seems to cause problems. In our experiment, we select three different DEMs: ASTER GDEM, a DEM derived from a digitized topographic map, and SRTM-3 in order to analyze the influence of the input DEMs for PS-InSAR processing in the Three Gorges area. We find that differential interferogram generation is related to the topographic influence for the PS-InSAR processing and different DEMs get us different PS-InSAR results.