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| Unsupervised Classification of Polarimetric SAR Image Using Deorientation Theory and Complex Wishart Distribution |
| Kang Xin①; Han Chong-zhao①; Xu Feng②; Wang Ying-hua① |
| ①Institute of Integrated Automation, Xi’an Jiaotong University, Xi’an 710049, China;②Key Laboratory of Wave Scattering and Remote Sensing Information, Ministry of Education, Fudan University, Shanghai 200433, China |
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Abstract Scatter targets of complex terrain surfaces with random orientation product random fluctuating echoes. This leads to a confused classification by directly using target decomposition on full polarimetric SAR (PolSAR) image. To solve this problem, a new unsupervised classification method is proposed in this paper. Firstly, the target vector is transformed to the state with minimization of cross-polarization (min-x-pol); then the parameters u/v/H are used to characterized scattering mechanism, and the fuzzy membership is adopted instead of "hard" division of parameter plan; finally, characterizing the coherency matrix as multivariable complex Wishart distribution, the polarimetric SAR image is classified based on Bayes maximum likelihood criteria. Experiment is performed on a L-band NASA/JPL SIR-C polarimetric SAR image over Danshui town, Guangdong, P.R. China. Furthermore, the movements of the clustering centers are discussed. Compared with the k-mean like method based on H/α, the results show that the proposed method provides a significant performance improvement in classification result and the associated scattering mechanism of class is more accurate. The classification result is beneficial for automatic recognition of terrain type.
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Received: 03 April 2006
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2007, Vol. 29 
