I have a problem in Qgis. I have two elevation maps, both is raster. They are both DEM maps, one showing the topography without buildings, and one showing the topography with buildings. From these two DEM's I want to make a new DEM showing the height of the buildings.
I tried to use the raster calculator
But this just generates a layer where nothing is shown.
The new DEM should be used to add a new attribute to the polygons stating the mean elevation within each polygon, any help on that aspect as well?.