Topic: Landslide detection
I have a Pléiades image from 16 July 2012 which I want to compare with a Pléiades image of 9 July 2013, using COSI-Corr to detect landslide displacements. Also, I have tristereo Pléiades images of the area of 9 july 2013 with which I made a georeferenced DEM. I have some questions in using COSI-Corr with this data:
1. When no pre-hazard and post-hazard (hazard=landslides) DEM's are available, it is assumed that the elevation stays constant, right? When we make this assumption, it would be no problem to analyse displacements from 2012 to 2013 with a DEM from 2013 ? In the COSI-Corr guide 2015a I read that both pre-earthquake image and post-earthquake image make use of the pre-earthquake image for selecting tie-points.
2. Why is a normal geocoded DEM not sufficient for orthorectification in COSI-Corr ? I read in the COSI-Corr guide 2015a, and all related papers, that a "shaded DEM" is used. No difficulty to create a shaded version, but I was just curious about their difference in the application.
3. COSI-Corr relies on pixel correlation, but I do not see an application for landslides here, as the pre-hazard image looks different than the post-hazard images on the places where a landslide occured, for example: from houses to debris. Or how do you see it ?
Looking forward to your answer,