A Classification Method Based on Polarimetric Entropy and GEV Mixture Model for Intertidal Area of PolSAR Image
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摘要: 该文提出了一种可用于全极化SAR的潮间带区域地物分类的方法。首先针对潮间带的特点对4种典型极化特征进行分析和筛选,得到一组最适合描述潮间带区域的多极化特征:极化熵(Polarimetric entropy)和反熵(Anisotropy)。然后基于对潮间带区域极化熵图像的散射特性分析和极值理论,利用广义极值分布(Generalized Extreme Value, GEV)描述其统计特性。在此基础上,提出了一种基于GEV混合模型的EM算法实现对潮间带地物分类的方法。最后,基于上海崇明东滩潮间带的Radarsat-2全极化数据进行了实验,实验结果证明了方法的有效性。
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关键词:
- 合成孔径雷达(SAR) /
- 多极化特征 /
- 广义极值分布(GEV) /
- 有限混合模型 /
- 潮间带地物分类
Abstract: This paper proposes a classification method for the intertidal area using quad-polarimetric synthetic aperture radar data. In this paper, a systematic comparison of four well-known multipolarization features is provided so that appropriate features can be selected based on the characteristics of the intertidal area. Analysis result shows that the two most powerful multipolarization features are polarimetric entropy and anisotropy. Furthermore, through our detailed analysis of the scattering mechanisms of the polarimetric entropy, the Generalized Extreme Value (GEV) distribution is employed to describe the statistical characteristics of the intertidal area based on the extreme value theory. Consequently, a new classification method is proposed by combining the GEV Mixture Models and the EM algorithm. Finally, experiments are performed on the Radarsat-2 quad-polarization data of the Dongtan intertidal area, Shanghai, to validate our method. -
图 6 GEVMM及其各分量与Gamma分布和log-normal分布的对比:(a)–(e)分别为5个分量与Gamma分布,log-normal分布以及对应标记区域的直方图的对比,其中蓝色区域为归一化直方图,绿线是GEV拟合结果,黑线是Gamma拟合结果,红线是log-normal拟合结果,(f)给出了GEVMM及其各个分量与研究区域直方图的对比结果,其中蓝线为归一化直方图,红线为GEVMM,绿线为GEVMM的各个分量
Figure 6. Fitness comparison among GEV distribution and Gamma distribution and Log-normal distribution of each component in GEVMM: (a)–(e) represent the five components of the GEVMM and the fitting results by the Gamma distribution and log-normal distribution for the histograms, which are marked as blue, the green lines represent the GEV fitting results, the black lines represent the most fitted Gamma distribution and the red lines represent the most fitted log-normal distribution, (f) shows the five components of GEVMN as green lines and the respective histograms as blue lines, the red line represents the final model
表 1 各极化特征的Michelson类间对比度
Table 1. Michelson between-region contrast of different features
极化特征 类间对比度 Span 0.4092 Entropy 0.7703 Anisotropy 0.9959 α 0.6757 表 2 GEV分布,Gamma分布和log-normal分布在每种类别中的拟合结果的AIC值
Table 2. The AIC values of the fitting results between the GEV distribution, the Gamma distribution and log-normal distribution
AIC 1 2 3 4 5 GEV 6.3988 4.0095 4.1105 4.7009 6.2093 Gamma 11.3878 9.3573 7.6928 9.0210 8.3989 log-normal 11.3878 9.3573 7.6928 9.0213 8.3997 -
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