[OSM-dev] Overlapping polygons - verboten or not?

Patrick Kilian osm at petschge.de
Wed Apr 20 05:23:52 BST 2011


> Can someone point me to an explanation/discussion about whether
> overlapping polygons are 'permitted' or not? I get a different answer
> every place I look, and I need to get this question out of the way
> before before I can even consider developing with OSM.
Overlapping polygons are definitly ok. A closed way with building=yes on
top of a landuse=residential area is perfectly ok and very common.

The rule is "don't create overlapping polygons of the same type". So two
landuse areas, say landuse=residential and landuse=forest, shouldn't
overlap. In the spirit of "be strict in what you send, be liberal what
you receive" you shouldn't create two such polygons, however your code
has to be robust enough to deal with such a situation in the existing data.

Patrick "Petschge" Kilian

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