Fig. 6. Building damages information extraction of sample blocks in Dujiangyan city from aerial photograph and TerraSAR-X image, the GIS data of blocks and buildings are
extracted from a pre-earthquake QuickBird image acquired on July 22, 2005: (a) aerial photograph of Hehuachi residential area acquired on May 18, 2008; (b) Backscattering
coefficient image of TerraSAR-X of Hehuachi residential area acquired on May 15, 2008; (c) building damage information of sample city blocks extracted from TerraSAR-X
image; and (d) index map showing the location of study blocks in Dujiangyan city.