Combination of low- and high-resolution SAR images for differential interferometry

The authors propose a combination of low-resolution (LR) and full-resolution (FR) SAR images for differential SAR interferometry. The principal problem in such a combination is the volume scattering decorrelation that limits the useful baseline of the interferometric pair to very small, impractical values. A technique has been introduced to remove this decorrelation by exploiting a digital elevation model (DEM) of the area imaged. The resulting interferogram has the quality (in terms of coherence or phase noise standard deviation) of a conventional FR interferogram, but reduced geometric resolution. The technique is suited to those differential interferometry applications where the resolution of the "differential" phase field to be monitored is much coarser than that of local topography. As a possible application, they propose a system that exploits the wide swath imaged by low-resolution ScanSAR modes for frequent monitoring of hazardous areas.