Fig. 2 shows the pre- and post-seismic IKONOS stereo images, and the distribution of the control points. All these points were used as GCPs and check points (CKPs) in the experiment. At the same time, the image coordinates of 44 points in the pre-seismic image and those of 62 points in the post-seismic image were carefully measured to a nominal accuracy of 0.5 pixels.