I have a set of Terrain data in both DSM and DTM form. What I am trying to do is extract the features (buildings, hedges etc...) that have been removed from the DTM, but I don't want the topography. The ideal end result would essentially be an elevation map of all the structures but on a flat plain rather than the rolling hills that are really there.
I have seen that the raster calculator could be used to extract all the parts of one set that are different to the other, but the bit I don't grasp is how I can then flatten the topography while keeping the relative height of the features.
I'm working in QGIS, but I also have access to LSS though I am not very experienced with it.