If you have the DSM you could potentially pull out the rough building footprints by looking at where elevation values jump a significant amount. This would indicate a vertical surface (side of a building) it would be pretty dependent on the resolution of your data, i'd be wanting sub meter data to undertake something like.

Alternately have you had a look at Open Street Map data for your area? They have pretty good coverage.

Also have a search through GitHub for Building Footprint extration, there are quite a number of public projects that people have shared that provide tools to achieve that task

Thanks for the reply. I've already looked at OSM and other sources with no luck. I'm working on a smaller city in Albania, and the gourvernments official website does not have footprints for this area either.

How would I go about locating elevation jumps in the dsm and getting shapes from that? I haven't worked with geotiffs like this before, but I guess I would have to extract elevation values for each pixel somehow? The resolution is 0,5 meters, which should be enough to get some results. The orthophotos are even higher resolution if I could somehow use those, or a combination. I know ArcGis has some tools for this, but I don't have a license.

Hi @robinosc​, I'd use a RasterExpressionEvaluator to compare the DSM and DTM. Following this comparison, positive cells should indicate above-surface objects. This should leave you with a raster datasets with positive cells for for example trees, buildings and son. After this, there are multiple ways to continue: you could use e.g. the orthophoto, area calculations and so on.