3. METHOD
3.1. Detecting flooded areas
Water bodies show low sigma naught due to the effects of
mirror reflection. To detect water bodies, threshold value was
determined focusing on the local minimum value in the histogram
derived using pre-event TerraSAR-X data. After removing
the noise by a majority filter, water bodies located in
high location is excluded using ASTER GDEM assuming that
is regardless of tsunami. Finally, the boundary of the flooded
areas is estimated by drawing the envelope of water bodies as
m, mean values of correlation coefficient and differences of
speckle divergence are calculated on each tile to identify the
relationship between damage ratio of washed away buildings
as shown in Fig. 5.