However, more points on the ground in DEM generation would much better describe the height variation of the ground between the buildings in both DEMs. The results can be seen in Fig. 10b and c. Hence, clear boundaries between the collapsed buildings and the ground are observed in the difference between the pre-seismic DEM created from the topographical map and the post-seismic DEM created from the stereo images, while there are no boundaries in some region of the difference between the pre- and post-seismic DEMs both created from the stereo image pairs. (2) Another possible reason for the appearance of the latter difference DEM might be that the collapsed buildings occupied the ground among them.