I’m looking for building contours for Saxony-Anhalt (3 Landkreise) to calculate the PV potential.
There’re data sources such as the official contours (“Hausumringe”)  and the digital landscape model BasisDLM  but none of these data are open.
Possible solutions I see:
- Buildings from OpenStreetMap: Great, but the coverage, especially in rural areas, is quite poor
- Extraction by color using WMS services from public raster maps, e.g.
2a) TopPlusOpen  (German BKG)
Works well, since buildings feature a defined color, but many buildings are missing here:
2b) WebAtlasDE  (vom BKG):
Apparently all buildings are included but it doesn’t work well as there’re overlain by captions and the color is not unique:
Do you have ideas/different approaches?
Do you know where to find appropriate maps/data sources that allow to implement the solution in 2)?