【摘要】 汶川地震发生后,受阴雨天气的影响,光学遥感影像在救灾决策中的作用受到了很大的限制,而SAR图像由于其全天候的特点成为这次抗震救灾前期遥感信息保障十分重要的数据源.采用ENVISAT的ASAR作为数据源,利用多时相的雷达数据的幅度及相位信息对映秀及周边地区做了地震灾害识别,其中利用震前震后的幅度图像做比值变化检测,在映秀镇及紫坪铺水库等山区取得了较好的效果;利用相位信息做干涉处理得到的相干图像,经过失相干分析,发现建筑物的破坏等级与相干系数变化指数的大小高度相关.比较这两种方法,在都江堰等平原地区由于失相干现象不像山区那么严重,并且利用比值处理可以去除部分空间失相干及系统热噪声等带来的干扰因素,可以成为幅度图像的有益补充.结果表明,结合SAR幅度影像和干涉相干影像,可以在地震灾害评估中取得更好效果.随着极化干涉雷达技术的日益成熟,多时相幅度信息、相位信息等多特征SAR影像信息的融合会在救灾决策中发挥更大的作用.更多还原

【Abstract】 Optical remote sensing imagery in decision-making for disaster relief after the 2008 Wenchuan earthquake was highly restricted due to rainy weather.However,the SAR image with its all-weather characteristics emerged as a very important data source of remote sensing information needed for the relief work in early days.In this paper,we conducted damage identification for Yingxiu town and its adjacent areas with ENVISAT ASAR as data source,using amplitude of multi-temporal radar data and phase information.The ratio change detection using pre-and post-earthquake amplitude images yielded satisfying results in Yingxiu town and Zipingpu reservoir.After decorrelation analysis,the coherence images obtained by interferometric processing with phase information showed that the damage grade of a building is highly related to the variability index of coherence coefficient.In plain areas such as Dujiangyan,decorrelation is not as important as in mountainous areas,and ratio processing can eliminate some of the spatial decorrelation and other interference factors caused by system thermal noise,therefore,ratio change detection can be used as necessary supplement to amplitude imaging.This study shows that the combination of SAR amplitude imaging and interferometric coherence imaging can produce better results in earthquake disaster assessment.As the polarization radar technology becomes more and more sophisticated,the integrated SAR image information of multi-temporal amplitude and phase information will play an important role in decision-making for disaster relief.更多还原