I have a series of building polygons which I would like to convert to a raster illustrating their height. I have the building heights but not their elevation above sea level datum. I have the underlying topographical data in a DEM. So, I was wondering if someone could show me an algorithm in the Field Calculator that will allow me to combine the two to arrive at a building elevation above sea level.
(Apologies if this is an easy question, I am a newbie to GIS, or has been asked before but I couldn't find it in the previous questions)
Yours in hope