Small Baseline Subset (SBAS) is a well-known technique of differential synthetic aperture radar (SAR) interferometry for the generation of surface deformation time-series by processing large sequences of SAR data acquired over the same region on Earth. The method requires the preliminary generation of pairs of SAR images collected by slightly different orbital positions at different acquisition times. The phase difference of the interferometric SAR data pairs is extracted. The two-dimensional phase maps contains different contributions, but principally a component due to the terrain height of the observed area. The DInSAR technique relies on the estimation of the deformation of the terrain between the two interfering SAR images (i.e., the so-called master and slave images). To achieve this task, the phase contribution related to the terrain height is simulated and subtracted to the interferometric master/slave phase difference. The obtained differential SAR interferometric phase contains a direct information on the occurred deformation. Once a sequence of interferometric SAR data pairs is selected, the SBAS technique allows generating the time-series of the deformation of the terrain. The processing steps are essentially: i) the extraction of the full phase of the DInSAR interferograms, i.e., the phase unwrapping steps of the DInSAR interferograms, ii) the inversion of the sequence of unwrapped DInSAR phases, iii) the geocoding of the deformation maps from radar coordinates to geographical coordinates.
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