Tomo and Diff-Tomo SAR methodologies: Recent advances for urban and forest applications

Interest is continuing to grow in advanced interferometric SAR methods for sensing of complex scenarios with multiple (layover or volumetric) scatterers mapped in the SAR cell. Multibaseline SAR tomographic (3D) elevation beam forming, i.e. spatial spectral estimation, is a promising technique in this field. Recently, the Tomo concept has been integrated with the differential interferometry concept, producing the advanced “differential tomography” (Diff-Tomo, “4D”) processing mode which produces “space-time” signatures of multiple scattering dynamics in the SAR cell. Advances in the use of these new frameworks are investigated in complex multiple scattering scenarios, also with temporal signal variations, both from scatterer deformation motions and temporal decorrelation. Results are reported of Tomo/Diff-Tomo single-look superresolution and light-burden processing in urban areas, with ERS data. Also, first results are shown of a “5D” extension of this Diff-Tomo processor handling non-uniform motions. Moreover, new results are reported concerning the potentials of Diff-Tomo for the analysis of volumetric forest scenarios, based on the original concept of the space-time signatures of temporal decorrelation. E-SAR P-band data trials are shown of separation of different temporal decorrelation mechanisms of canopy and ground, and of monitoring possible sub-canopy subsidences.