An analysis about the effect of reflection asymmetry compensation on the Freeman-Durden/Wishart classification

Freeman-Durden/Wishart classification proposed by J. S. Lee is an effective unsupervised polarimetric SAR data classification method in many cases. However, it may encounter problems when the reflection symmetry assumption as a basic condition of Freeman-Durden decomposition isn´t satisfied which may induced by azimuth slopes or rotation of man-made target with respect to the radar along-track direction. Some research works have been done to compensate for the reflection asymmetry. In this paper, classification results using unsupervised Freeman-Durden/Wishart classification method with and without reflection asymmetry compensation were compared and discussed. The experiment demonstrates that applying reflection asymmetry compensation before Freeman-Durden decomposition can rectify the dominant scattering mechanism of buildings rotated by a small angle with respect to the radar along-track direction, thus can improve the classification accuracy between rotated buildings and volume scattering targets such as forests in the Freeman-Durden/Wishart classification.