https://wiki.openstreetmap.org/wiki/DE:JOSM/Basic_editing https://wiki.openstreetmap.org/wiki/DE:JOSM/Plugins/BuildingsTools https://www.mapbox.com/blog/fast-building-tracing/ http://wiki.openstreetmap.org/wiki/Using_Imagery#JOSM http://wiki.openstreetmap.org/wiki/DE:Roof_modelling