Dem Registration, Alignment and Evaluation for Sar Interferometry

To generate an accurate digital elevation model (DEM), Interferometric Synthetic Aperture Radar (InSAR) requires precise orbit data and baseline information, which are not always available. An alternative approach is to apply quality ground control points (GCPs) into the InSAR processing. However, locating high quality GCPs can also be difficult task, due to the low spatial resolution and radiometric response of synthetic aperture radar (SAR) images. This paper presents a method to register and align an InSAR DEM, generated from SAR images without precise orbit or baseline information and without GCPs, to an existing coarse reference DEM for refinement. The results showed this method achieves a comparable or even better accuracy than applying GCPs into InSAR processing. It was also found that the existing DEM with lower resolution than the InSAR DEM could be a good reference for this registration and alignment, i.e. refinement. ERS1/2 tandem SAR image pairs were used for 16-meter (post spacing) InSAR DEM generation. Both InSAR processing with and without applying GCPs were conducted for comparison purposes. The InSAR DEM was registered and aligned to SRTM 3 Arc Second data, a global reference DEM. The “truth” DEM used for accuracy evaluation is a higher accuracy DEM from aerial imagery with post spacing of 1.5 meters and vertical accuracy of 1.8 meters.