High Resolution InSAR Topographic Mapping Comprehensive Experiment in Hengduan Mountain Area

Due to steep terrain relief and complex geomorphic types in Hengduan Mountain area, COSMO tandem with short temporal separation and the interferometric baseline revealed high potential for large area topographic mapping. Topography is mostly serious with steep slopes and covered by permanent snow. Furthermore, the quality of the InSAR DEM may vary significantly depending on the local topography. Interferometric processing consisted of coregistration of COSMO image pairs, multi-looking, range and azimuth direction filtering, interferogram generation and coherence map calculation, phase unwrapping; in areas of low coherence larger windows were used to reduce the uncertainty and bias of the estimation. For the geocoding of the COSMO DEM, Range-Doppler model based on few control points was used to build the relationship between ground point geodetic coordinates and image coordinates. Maps have been produced for a 15 000km² large area in China in western mapping project. At present, the proposed method, technical flow and software module has been widely used in the 1:50000 Scale Topographic Mapping Project in Western China. The experiment result proves that it is effective and practical.