Model-Based Polarimetric SAR Target Decomposition: A Scheme to Introduce Repeat-Pass PolInSAR Coherence.

Polarimetric Synthetic Aperture Radar (PolSAR) target decomposition is an effective way to obtain the scattering mechanism information. However, the problem of volume scattering overestimation in rotated built-up areas has not been completely addressed even with extensive efforts in scattering modeling. The root lies in the scattering ambiguity in polarization response ( S matrix, T matrix and C matrix) which is difficlut to remove. To handle this problem, the repeat-pass Polarimetric Interferometric Synthetic Aperture Radar (PolInSAR) coherence is introduced to PolSAR target decomposition in this paper, to distinguish the volume scattering and the scattering generated by rotated dihedral structures and then achieve the volume scattering component correction. Specifically, a building descriptor P_bd is established based on PolInSAR coherence and then used to distinguish natural and built-up areas before target decomposition. Then, two different scattering model sets, where the volume scattering and the rotated double-bounce scattering do not appear at the same time, are applied in natural and built-up areas, respectively. Applying the above two points to classic decomposition methods, a series of improved methods are proposed, named repeat-pass PolInSAR coherence-assisted target decomposition methods. Experiments on three sets of PolInSAR data confirm the validity of the proposed decomposition methods. Besides, time series PolInSAR data are used to analyze the performance of the algorithm under different temporal baseline conditions. This work may enlighten how to efficiently correct the volume scattering component in rotated built-up areas by introducing repeat-pass PolInSAR coherence into PolSAR target decomposition, to reduce the large amount of energy spent on the complex scattering modeling.