Table 2 shows that the status of the collapsed buildings can be
determined employing the proposed method as discussed in Section
3.3.2. For example, in the case of Building No. 1, the heights
of the four corner points as calculated from the post-seismic stereo
pairs are lower than those of the corresponding points as calculated
from the pre-seismic stereo pairs, and the values of the height
reduction are almost the same for the four corner points. Meanwhile,
the number of collapsed storeys is calculated to be five or
six. Therefore, it is considered that this building totally collapsed
in the earthquake. However, in the case of Building No. 2, the
heights of the first two corner points calculated from the preand
post-seismic stereo images are almost the same, and the number
of collapsed storeys calculated from the first two corner points
is close to zero, while the heights of the other two corner points as
calculated from the post-seismic stereo pairs are lower than those
calculated from the pre-seismic stereo pairs, and it is estimated
that about five storeys collapsed. Therefore, the building is determined
to be partially collapsed. Furthermore, in the case of Building
No. 3, the heights of the four corner points are almost the same
before and after the earthquake. Therefore, it is judged that the
building has not collapsed during the earthquake. Similar conclusions
can be made on the status of the rest buildings during the
earthquake. Comparing to the ground truth, we can see that the
status of a total of eight buildings (i.e., totally collapsed, partially
collapsed and not collapsed) are correctly detected by our proposed
method.