(1) Under the assumption that the post-seismic height of a collapsed building is lower than the pre-seismic height, the region of collapsed buildings is determined from the
difference DEM through setting the threshold value of detecting the height changes of buildings due to the earthquake.In the experiment, a threshold value of 5 m was set
on the basis of in situ observations; that is, if the height changes are larger than 5 m in the difference DEM, then buildings in that region are judged to have collapsed.
Fig. 11 shows that both difference DEMs can determine the region of collapsed buildings