From Interferometric to Tomographic SAR: A Review of Synthetic Aperture Radar Tomography-Processing Techniques for Scatterer Unmixing in Urban Areas

Cross-track synthetic aperture radar (SAR) interferometry is a powerful technique that analyzes the phase shift each pixel undergoes between acquisitions of the same scene with just a slight change of viewpoint. These phase shifts provide information about the topography and, when more than two acquisitions are available at different dates, about possible slow motions along the line of sight, related to subsidence and/or thermal dilation, of the dominant scatterer in the resolution cell. However, interferometric processing exploits phase-only data, does not provide scatterer distribution in the vertical direction, and is not able to separate multiple scatterers lying in the same range/azimuth resolution cell.