3D Imaging for Array InSAR Based on Gaussian Mixture Model Clustering
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摘要:
阵列干涉SAR具备高程分辨能力,单次航过即可生成观测场景的3维点云分布,解决叠掩问题。但是,由于阵列干涉SAR阵元数目有限、基线长度较短,高程向分辨率受到限制,加之城区建筑物的叠掩现象,常规方法重建结果定位精度较差,难以提取建筑物有效特征。针对这个问题,该文提出了一种基于高斯混合聚类的阵列干涉SAR 3维成像方法,首先通过基于压缩感知(Compressive Sensing, CS)的超分辨算法获得场景区域的3维点云分布,然后利用密度估计方法提取出建筑物的散射点,之后使用高斯混合模型(Gaussian Mixture Model, GMM)对建筑物3维点云进行聚类,最后利用系统参数完成各个区域的SAR图像反演,实现建筑物的3维成像。通过国内首次机载阵列干涉SAR实验的实际数据,验证了该文算法的有效性,并获得了真实的建筑物3维成像结果。
Abstract:Array InSAR can generate 3D point clouds with the use of SAR images of the observed scene, which are obtained using multiple channels in a single flight. Its resolution power in elevation enables one to solve the layover problem. However, due to the limited number of arrays and the short baseline length, the resolution power in elevation is restricted. Together with the layover phenomenon of the urban buildings, the result of 3D reconstruction suffers from poor accuracy in positioning, and it is difficult to extract the effective characteristics of the buildings. In view of this situation, this paper proposed a 3D reconstruction method of array InSAR based on Gaussian mixture model clustering. First, the 3D point clouds of the observed scene are obtained by an algorithm with super-resolution based on compressive sensing, and then the scatters of buildings are extracted by density estimation; after which the method of Gaussian mixture model clustering is used to classify the 3D point clouds of the buildings. Finally, the inverse SAR images of each region are obtained by using the system parameters, and the 3D reconstruction of the buildings is completed. Based on the actual data of the first domestic 3D imaging experiment by airborne array InSAR, the validity of the algorithm is confirmed and the 3D imaging results of the buildings are obtained.
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表 1 阵列干涉SAR系统参数
Table 1. System parameters of array InSAR
项目 参数 载频(GHz) 15 发射信号带宽(MHz) 500 脉冲重复频率(kHz) 1 载机高度(m) 600 飞行速度(m/s) 70 方位波束宽度(°) 2 距离波束宽度(°) 27 中心下视角(°) 25 表 2 不同窗口/阈值质量评价表
Table 2. Quality evaluation with varying TH and GA parameters
TH
(点数/dm2)GA (dm2) 1×1 2×2 3×3 4×4 5×5 1 75.12 74.88 74.37 71.89 71.75 2 81.27 81.86 81.73 77.71 78.07 3 94.12 93.84 94.82 94.63 94.08 4 87.48 86.32 86.40 81.98 77.56 5 81.89 84.77 84.68 78.29 77.91 6 67.23 63.02 67.14 60.62 51.83 -
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