Is there a scientifically-valid to use raster calculator to subtract two binary images (0, 1) to get the difference between Pre- and Post flood events?
Difference "change detection" = Post-event flood event (1,0) - Pre-event flood event (1,0)
I tried it and got difference map, but I want to make sure it is valid method.
There are 4 possible cases:
- recorded flood events in the post- and pre-images and the result would be (1-1=0), 2
- flood event in the post-image and no flood in the pre-image, and the result would be (1-0=1),
- non-flood in the post-image and flood in the pre-image, and the result would be (0-1=-1),
- non-flood in both post-and pre-images, so the result would be (0-0=0).
The main concern around the interpretation of the third case.