基于极化分解组合的SAR图像视觉优化和建筑物损毁评估

SAR image visual optimization and building damage assessment based on polarimetric decomposition combination

建筑物损毁评估对灾害应急监测具有重要意义。极化SAR图像蕴含丰富的地物信息,并且记录有目标地物的极化散射矩阵,可用于建筑物的损毁评估。针对完好和损毁建筑物两类目标的散射特征,利用Touzi分解散射角αs1、去定向后Yamaguchi分解二次散射分量和Touzi分解散射对称度τ2进行RGB彩色合成,对极化SAR图像进行视觉优化,进而利用单一时相SAR图像快速识别出不同损毁程度的建筑物区域。以2011年3月11日发生在日本东北部海域的地震为例,利用灾后的ALOS PALSAR全极化数据开展实验分析,并利用汶川地震RADARSAT-2图像对提出的方法进行验证。结果表明,通过对极化参量的组合不仅可以优化建筑物目标的视觉显示效果,同时可提高不同损毁程度建筑物区域识别度,从而大大降低灾害评估对于数据源的限制和要求。

Building damage assessment is of great significance for disaster emergency monitoring.Polarimetric synthetic aperture radar(SAR)records the polarization scattering measurement matrix of ground objects and obtains abundant ground object information.Therefore it can be used for building damage assessment.Based on scattering characteristics of intact and damaged buildings,the scattering angleαs1 in Touzi decomposition,the double-bounce scattering component in Yamaguchi decomposition after deorientation,and the symmetryτ2 in Touzi decomposition are combined for color composition and optimizing the polarimetric SAR image.This method can be used to quickly identify the building areas with different damage degrees by using single phase polarimetric SAR image.We take the March 11th,2011 earthquake that struck the coast of northeast Japan as an example and use quad-polarimetric ALOS PALSAR data acquired after the disaster for the analysis.The proposed method is verified by using RADARSAT-2 image of Wenchuan earthquake.The results show that the combination of polarimetric parameters not only optimizes the visual display effect of building targets,but also easily identifies the building areas with different damage degrees.This method greatly reduces the limitation and requirements for data source in disaster assessment.