Abstract:A new method for unsupervised classification of terrain types using fully POLarimetric Synthetic Aperture Radar (POLSAR) data is proposed in this paper. The method is a combination of the unsupervised classification based on Cloude’s H-α decomposition and the modified C-mean algorithm. The fully polarimetric SAR image is initially classified using Cloude’s method. The classification map is used as input of the modified C-mean algorithm, and then iteration is performed. It is important to determine the number of iteration in the modified C-mean algorithm, and a new termination criterion is presented using image entropy to do so. Compared with H-α decomposition, not only scattering mechanisms of all classes can be preserved, but also terrain classification is effectively performed using this method. The effectiveness of this method is demonstrated using an L-band fully polarimetric SAR image of San Francisco, acquired by the NASA/JPL AIRSAR sensor.