How good (or bad!) are those “cheap” range finders? How big does the “target” need to be? What is the range? 100m? 1km? I’d love to see a post with a bit more detail about those!

Nice work, and a very good write-up!

Looks like there are some remaining issues with invalid polygons, however. For example, relation 9727078, way 699994013, uses the same node twice (6537466518). Relation 9712099, way 698995586 touches itself, but without using a repeated node. Both are flagged as warnings by the JOSM validator, but I believe self-touching polygons are considered invalid.

(I am Swedish, writing in English just for consistency with the diary entry :-) )