Talk:Overpass turbo/Polygon Features

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Shouldn't you mention here that a name=* is needed for a polygon to be an area in Overpass turbo? - redrat

For searching them may be, but I don't think this aplies to all polygons you can retrieve with Overpass queries. Areas can be computed for some categories even if they don't have a defined name, for example ponds or forests (whic hare frequently fragmented using custom or administrative boundaries or some other interal physical boundaries such as riverbanks).
It may even make sense to search for riverbanks even if they are left without names (in one of the various arms of a river). — Verdy_p (talk) 18:46, 3 September 2017 (UTC)
Indeed I was searching for leisure= areas, named or not, but I found only named were retrieved by the query. My concern is mainly about documentation though also I don't understand the reason for this. According to [1] actually only named polygons are computed as area. - redrat 19:38, 3 September 2017 (UTC)
Well, there are two different things at play here: One is the list of Overpass areas you can query and use as search filters in an overpass query. The other thing is what tags are used inside Overpass turbo to determine which features should be drawn as polygons rather than closed lines (think of a building versus a roundabout: in OSM both are typically closed ways, so a list of tags is needed to find out how to actually draw them). This page and list of tags was created only for the second use-case.
It is true that Overpass-API uses a very similar list (the one you already found on github), which was originally adapted from this list here. But it is made for a different purpose. And for performance reasons (I think), that list only includes named areas (because otherwise one would end up with too many areas, which can't be processed on the server anymore).
-- Tyr (talk) 09:40, 4 September 2017 (UTC)