Commons has a lot of maps, aerial images etc. many of them have an overlay KML files associated with it. For example File:Warsaw Ghetto Map - 1940-10-15a.png
has File:Warsaw_Ghetto_Map_-_1940-10-15a.png/overlay.kml associated with it which can be accessed through this link.
It would be great if we could do the same by overlaying in top of Kartographer OSM maps. KML requires 4 corner coordinates, however what is often easier to get are 3+ anchor points (lat/lon + row/col) , which can be used to calculate corner points. Also /overlay.kml "sub" pages in image namespace are not well supported by current software, since file namespace does not support subpages. If we continue to use subpages we should allow them.
Next step would be an interactive software to add anchor points.