Polarimetric SAR interferometry

Abstract

In this work, aspects of electro-magnetic vector wave propagation and scattering are considered in relation to investigations on the role of polarisation in Synthetic Aperture Radar Interferometry. Based on the Maxwell equations, the underlying principles of Radar Polarimetry and SAR Interferometry are introduced in order to treat a general formulation of vector wave interferometry. It is shown how polarimetric basis transformations may be introduced in SAR interferometry in order to form interferograms between all possible polarisation states. This reveals the strong dependency of the interferometric coherence on the polarisation states used to form the interferograms. Then, the coherence optimisation problem, involving maximisation of interferometric coherence, is solved, leading to a new coherent polarimetric interferometric decomposition. For the interpretation of the addressed techniques, a simplified stochastic model for an elevated forest canopy is developed, and used to demonstrate the relevance of wave polarisation on the physical interpretation of SAR interferograms. Finally, the technique of polarimetric differential interferometry is introduced. The proposed algorithms are tested against fully polarimetric (scattering matrix) interferometric SIR-C/X-SAR data sets collected during 1994 along the Tien Shan test site over the SE Baikal Lake, Selenga Delta region of Buriatia in South-East Siberia, Russia.