Investigating the combined use of differential SAR tomography and PSI for spatio-temporal inversion

Persistent Scatterer Interferometry (PSI) inherently assumes a single temporally coherent scatterer inside a range-azimuth resolution cell. This restriction leads to the rejection of numerous persistent scatterer (PS) candidates, particularly in urban areas where layovers occur frequently. Moreover, in case of high-rise buildings, it is necessary to compensate the phase associated with thermal expansion in an iterative way. It is worthwhile to approach tomographic techniques to address these concerns. SAR tomography has the potential to separate scatterers in elevation, thus resolving layover. Differential SAR tomography additionally allows retrieval of deformation parameters, including a possible thermal expansion term. In this paper, we investigate the combined use of SAR tomographic approaches and PSI for elevation and deformation estimation. Results are presented for an interferometric time-series of 50 TerraSAR-X stripmap images acquired over Barcelona city. Spatio-temporal inversion of scatterers along the façade of a high-rise building is presented as a special case.