Would it be possible to display rectified maps from c:Commons:Wikimaps on top of a basemap drawn from OSM?
Topic on Help talk:Extension:Kartographer
It's not possible possible to embed those in articles(Kartographer), but if you just wan't to view them elsewhere there is a/an:
gadget for Wikimedia Commons: https://github.com/Abbe98/commons-warper-viewer.js
embed service on Tool Labs: https://tools.wmflabs.org/warped-to-iframe/map.php?pageid=35092716&wmf=true
Ok. I knew about the extensions you're showing, but I was really hoping that this feature would also be enabled on Wikipedia. Being able to show map layers in an article would be an incredible way to add information. But who knows, maybe it gets implemented at some later point in time?
It can be done using the template OSM Location Map, which is on en and now various other wikipedias. As well as text and dots and shapes, suitable transparent map overlays can be added from a commons file. There is an example at https://en.wikipedia.org/wiki/East_Northamptonshire which overlays the county boundary as a semi-transparent overlay. The tricky bit is getting the overlay at the same scale and position as the OSM map.
@AWossink it would require quite a lot of work to make Kartographer work with rectified maps at this point. I think when Structured data on Commons might help one day.