Building Earthquake Damage Information Extraction from a Single Post-Earthquake PolSAR Image

Wei Zhai,Huanfeng Shen,Chunlin Huang,Wansheng Pei

doi:10.3390/rs8030171

Abstract

After an earthquake, rapidly and accurately obtaining building damage information can help to effectively guide the implementation of the emergency rescue and can reduce disaster losses and casualties. Using a single post-earthquake fully-polarimetric synthetic aperture radar (PolSAR) image to interpret building damage information not only involves a guaranteed data source but is also easy and can be rapidly implemented. This paper is focused on rapid building earthquake damage detection in urban areas using post-earthquake PolSAR data. In PolSAR images, the undamaged buildings parallel to satellite flight pass are different from the collapsed buildings, but the undamaged buildings divergent to satellite flight pass are very similar to collapsed buildings because of their volume scattering characteristics. In this paper, the method of polarization orientation angle (POA) compensation is employed to increase the scattering power of buildings divergent to satellite flight pass, and then Wishart supervised classification is implemented on the PolSAR data after POA compensation. In addition, the two parameters of normalized difference of the dihedral component (NDDC) and ρHHHV are proposed to improve the classification accuracy of the Wishart supervised classification, and both the undamaged buildings and collapsed buildings are determined. The study was carried out after the “4.14” Yushu earthquake in Yushu County, Qinghai province, China. The three damage levels are set for the urban area at the city block scale according to the values of the BBCR building damage index. The experimental results confirm that the scheme proposed in this paper can greatly improve the accuracy of the extraction of building damage information.

Highlights

In recent years, earthquake disasters have become more frequent around the world
The experiments were carried out on the post-event airborne polarimetric synthetic aperture radar (PolSAR) imagery to validate the effectiveness of the proposed approach for earthquake damage assessment
In this study of earthquake damage assessment, the two parameters of the normalized difference of the dihedral component (NDDC) and ρHHHV were used to improve the classification results of Wishart supervised classification performed on the PolSAR data after polarization orientation angle (POA) compensation, with the aim of obtaining non-buildings, undamaged buildings, and collapsed buildings

Summary

Introduction

Earthquake disasters have become more frequent around the world. The earthquake is one of the most dangerous natural disasters for human beings, and tens of billions of dollars in property loss are caused by earthquakes every year. Earthquakes cannot be predicted accurately at the current scientific level. Rapid and accurate damage assessment can help to reduce the disaster loss and can provide decision support for the rescue and reconstruction efforts. 2016, 8, 171 the places where people live, and most of the casualties and economic losses in an earthquake are caused by the damage to buildings [1]. Building damage assessment is one of the most important parts of earthquake damage assessment

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Conclusion