Some time ago I was proposing to introduce topology rules, at least locally. Those (besides a lot of other stuff) would cover which polygons can be above which polygons, which polygons can not be above which polygons etc. Such rules are already used for years in Lithuania in regards of forests.
F.e. landuse=forest can not intersect/cover landuse=residential|industrial|commercial|reservoir, natural=water, waterway=riverbank. But for small patches of trees we use natural=wood, which can ONLY be above (be covered by) landuse=residential|commercial|industrial. Idea is that for large scale maps you use all of these polygons (with natural=wood on top) and for small scale maps you simply ignore natural=wood. This simplifies cartographic tasks a lot. It is also capable of separating micromapping without the need for complex generalisation calculations. As far as I understand, landcover tags are supposed to be used for exactly the same tasks (as natural=wood in my example). This means that all natural=wood polygons in Lithuania (not too much - 1500) could be replaced with landcover=wood|forest|trees (whatever) if that was rendered in OSM-Carto, as some people in Lithuania still use OSM-Carto data visualisation and not the local OSM maps. If I understand correctly, landuse=grass is the same thing for grass: landuse=grass is a micromapping (for large scale maps only), landuse=meadow is for smaller scale (actual landuse) mapping. So you could have the same topology rules in Netherlands to check automatically that all landuse=grass is above some actual landuse (hence the need for landcover to be able to have both). This way there would be an automated way to check quality of OSM data. IMPORTANT: There is no way to ensure the quality of OSM data without automated checks doing MOST of the work. -- Tomas _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
