Phase Correction of Single-Look Complex Radar Images for User-Friendly Efficient Interferogram Formation

Abstract

We present a new interferometric synthetic aperture radar processing approach that removes topography–dependent phase from single-look complex (SLC) radar images, making interferogram formation more efficient. We first adopt motion compensation techniques to resample SLC images with respect to an ideal reference orbit and then separate the residual topographic phase contributions into parts dependent only on individual SLC acquisitions, and generate topography-compensated images directly in latitude–longitude coordinates. Since the number of interferograms is typically much larger than the number of SLC images, our approach greatly reduces needed computational resources. Furthermore, we move the need for precise knowledge of imaging geometry upstream from the end user to the data provider. We demonstrate our approach for both preprocessed SLC images and raw data using COSMO-SkyMed L1A and ALOS L0 products. The performance of our method depends on the quality of the digital elevation model (DEM) used—DEM error affects the correction phase proportionally to the baseline between radar scenes and the reference orbital path. With a 1000-m baseline and a nominal 30° incidence angle, we find that the uncertainty of estimated deformation increases by approximately 1 cm with every 3 m increase in the DEM error.