人工衛星SAR強度画像による建物被害地域の検出手法

抄録

An imaging radar called synthetic aperture radar (SAR) has rapidly become one of the major tools for observing the earth's surface and its change. One of the distinctive characteristics of SAR systems is their capability of recording both amplitude and phase of the backscattering echoes from objects on the earth's surface in all weather conditions, day and night, and independence of sun illumination. SAR installed on the satellites JERS and ERS observed Kobe area before and after the 1995 Hyogo-ken Nanbu, Japan earthquake. Backscattering properties such as the difference and the correlation of the backscattering coefficient called Sigma-nought from the damaged areas by the earthquake were investigated. By analyzing the time-series SAR data, we clarified that the decreasing of the values of the difference and the correlation in the hard-hit areas was due to the surface changes by the event. Then, we developed an automated method to detect hard-hit areas based on the discriminant analysis using pre- and post-event SAR images. Furthermore, the accuracy of the proposed method was verified by comparing the results from detected areas and the one of the actual damage survey.