Multidimensional SAR tomography: Advances for urban and prospects for forest/ice applications

Research and application is spreading of techniques based on coherent combination of SLC (amplitude and phase) SAR data to extract rich information even on complex observed scenes, fully exploiting existing SAR data archives, and new tandem satellites. Among such techniques, Tomo-SAR stems from multibaseline interferometry to achieve full-3D imaging through elevation beamforming. The Tomo concept has been integrated with differential interferometry, producing the new Differential Tomography (Diff-Tomo) processing mode, that allows "opening" the SAR cells in complex non-stationary scenes, resolving multiple heights and deformation velocities of layover (double) scatterers, with typical application to urban scenarios. More recently, unique Diff-Tomo enabled capabilities of velocity profiling and robust reflectivity profiling of non-rigid and/or decorrelating volumetric scatterers have been unveiled. In this paper, recent experiments carried out at University of Pisa and at the RaSS Nat. Lab. of the Italian National Consortium for Telecommunications, and latest advances are presented of Diff-Tomo techniques for the efficient reconstruction and monitoring of complex urban/infrastructure deformating scenarios with new generation VHR SAR data. In particular, a new 4D Diff-Tomo model-based method with single-look light-burden superresolution capabilities is reported, and validated with COSMO-SkyMed data. Moreover, a new "5D" Diff-Tomo modelbased method for non-uniform motion (thermal dilation) monitoring at superresolution is tested. Finally, other Diff-Tomo enabled functionalities for ice and forest applications are recalled and more recent related results presented.