Offset Tracking With Geocoded SLC

There is a growing trend toward making synthetic aperture radar (SAR), interferometry SAR (InSAR), and their applications are more accessible to end users. Directly delivering geocoded, co-registered, and flattened SLC data (GSLC) eliminates the need for the complex geocoding and co-registration procedures which require professional domain knowledge and software. GSLC products dramatically simplify InSAR processing flows, making InSAR products easily available to a wide range of users. However, challenges still exist for SAR/InSAR analysis using GSLC datasets. In this article, we analyze the feasibility of using GSLC for deformation measurements based on offset tracking, both in theory and practice. We find that correct GSLC offset tracking requires the input GSLCs to be: 1) unflattened; 2) deramped; and 3) adequately sampled. We also show that the direct result from GSLC offset tracking is a projection of displacement in the slant range and azimuth directions. We can transform the offset measurement from GSLCs to the deformation field, but the current transformation relation is not precise enough. This research may help deepen the understanding of GSLCs and their applications.