On Monday 28 May 2018, Ture Pålsson wrote: > > > > landuse=residential and landuse:secondary=retail is what is > > happening on the ground in some places. > > Random thoughts: > > Does this really buy anything compared to overlapping polygons > (except, obviously, where the polygons are coincident, in which case > it saves a polygon)?
It was not my intention to push this idea here or to advocate a particular use case. If you as a mapper find it useful then use it, otherwise don't. But creating two separate geometries to document different properties of the same real world objects, like the ground conditions in a wood/forest, is both pretty pointless and against OSM principles. And semantically it is not clear in such a case which geometry represents the primary characterization of the area (what the area *is* so to speak) and which is a secondary characterization. In general the meaning of overlapping polygon geometries is - with the exception of some situations where both geometries are clearly on different semantic levels - fairly undefined in OSM. In many map styles including the standard style most land based area types that are rendered are sorted by size meaning that small polygons are interpreted as superseeding large geometries in meaning if they overlap. But this is not a rule you can rely on. So as a general rule for mapping: If you want to be clear and non-ambiguous you should typically avoid overlapping geometries of different feature types of the same or similar semantic levels. -- Christoph Hormann http://www.imagico.de/ _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
