Multi-feature-based classification method using random forest and superpixels for polarimetric SAR images

  • role: First author第一作者
  • Affiliation:

    China Communications Construction Company Second Highway Consultants Co.Ltd, Wuhan 430056, China

  • Email:xu_qiao_cug@126.com
  • Introduction:徐乔,1991年生,男,工程师,研究方向为公路地质灾害遥感监测。E-mail:xu_qiao_cug@126.com
XU Qiao1,  
  • Affiliation:

    China Communications Construction Company Second Highway Consultants Co.Ltd, Wuhan 430056, China

ZHANG Xiao1,  
  • Affiliation:

    China Communications Construction Company Second Highway Consultants Co.Ltd, Wuhan 430056, China

YU Shaohuai1,  
  • Affiliation:

    Faculty of Information Engineering, China University of Geosciences(wuhan), Wuhan 430074, China

CHEN Qihao2,  
  • role: Corresponding author通信作者
  • Affiliation:

    Faculty of Information Engineering, China University of Geosciences(wuhan), Wuhan 430074, China

  • Email:liuxg318@163.com
  • Introduction:刘修国,1969年生,男,教授,研究方向为遥感影像信息提取与3S集成。E-mail:liuxg318@163.com
LIU Xiuguo2*

реферат

The classification technique plays an important role in the analysis of polarimetric synthetic aperture radar (PolSAR) images. PolSAR image classification is widely used in information extraction and scene interpretation or is performed as a preprocessing step for further applications. However, speckle noise appears in PolSAR images because of the coherent interference of waves reflected from elementary scatters. Such inherent speckle noise degrades the classification performance and brings difficulty for PolSAR image classification. Therefore, a novel supervised multi-feature-based classification method was proposed in this study. This method combined polarimetric signature information and spatial context information based on the random forest model. First, a modified simple linear iterative clustering algorithm was utilized to generate superpixels as classification elements by using the Pauli RGB image, which helped reduce speckle noise interference. Second, a high-dimensional polarimetric SAR feature image was constructed by collecting various polarimetric signatures generated by polarimetric decomposition and algebra operations. Then, the random forest model was trained on the basis of the PolSAR feature image by using training samples, and the number of classification votes of each decision tree in the random forest for each pixel was counted to compute the class probabilities of the superpixels. Finally, a neighborhood function was defined to express the spatial relationship among adjacent superpixels quantitatively, and the class probabilities of the superpixels were recalculated by the predefined neighborhood function in a Probabilistic Label Relaxation (PLR) procedure to reduce the interference of speckle noise. The final classification result was obtained by the maximum a posteriori decision rule when the iteration of PLR was terminated. Comparative experiments using different RADARSAT-2 images were conducted to evaluate the validity and applicability of the proposed method. The proposed approach achieved the highest accuracy (94.39% on the Flevoland RADARSAT-2 image and 85.09% on the Wuhan RADARSAT-2 image) and generated accurate and consistent classification results for the experimental images, which was considerably improved compared with those of other methods. Therefore, the proposed method can effectively suppress the interference of speckle noise by using superpixels and spatial context information and obtain accurate and consistent classification results for PolSAR images.

ключеви́че слова́

remote sensing;polarimetric SAR;classification;multifeature;Random Forest;superpixels;probabilistic label relaxation

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