New polarimetric coherence parameter for built‐up areas in PolSAR imagery.

Fully polarimetric synthetic aperture radar (PolSAR) data are represented by four channels and the coherences between two arbitrary channels are important descriptors for the interpretation of polarimetric scattering mechanisms. However, there exists a scattering ambiguity between oriented urban and natural areas since they both contribute to the cross‐polarised (HV) scattering. A polarimetric correlation coefficient ratio is proposed to overcome this scattering ambiguity in PolSAR imagery. First, the polarimetric coherences of urban areas with various orientation angles were analysed. Subsequently, it was found that the proposed coherence parameter considers the reflection asymmetry of buildings and also the scattering divergence between co‐polarised and cross‐polarised channels, which is beneficial to the scattering analysis in urban areas. The effectiveness of the proposed parameter is demonstrated using the Phased Array type L‐band Synthetic Aperture Radar dataset. [ABSTRACT FROM AUTHOR]