Phase Unwrapping for Large-Scale P-Band UWB SAR Interferometry

Phase unwrapping (PU) for large-scale images is a new challenging problem in reconstructing a digital elevation model from synthetic aperture radar interferometry (InSAR) data. In this letter, we proposed a region-partition-based PU method that could improve the efficiency and decrease the processing memory of the large-scale PU problem for P-band ultrawideband (UWB) InSAR. The interferometric phase is flattened by the reference phase, which is generated from the shift estimation in the registration step. We refer to the residual phase as the misregistration phase (MRP), which corresponds to the error of the shift estimation. The MRP is unambiguous in most of the area with high coherence because of the large fractional bandwidth; thus, the regions that assuredly have the unambiguous MRP are partitioned out from the MRP image and referred to as the high-quality area. Meanwhile, the remaining low-quality areas are separated by the high-quality areas and are considered irregular tiles. After unwrapping the tiles by a minimum discontinuity PU algorithm either in parallel or in series, the full-size unwrapped result is obtained. The test performed on real P-band UWB InSAR data confirms the effectiveness and efficiency of our method.