Ben Supnik wrote:
Hi Y'all,
Does anyone have a good set of heuristics for the cases where
OSM-reading software should treat outer-way attributes as applying to a
multipolygon?
From what I can tell there are two possible cases I should look at:
- If the outer multipolygon has _no_ tags (other than type=multipolygon)
then I should probably go get some attributes from the outer ways, or
else the whole multipolygon is a no-op.
- If the outer multipolygon only has one way, then __maybe_- that way
might contain all of the attributes I care about? This second one makes
me nervous because I could have a state park way where the boundary of
the park is a water way with an island in it...the island (inner way)
might be meant to cut a hole in some attributes (like water) but not
others (like park).
You can see it the other way around: If the multipolygon _has_ tags
(other than type=multipolygon), then these tags fully describe the
multipolygon.
If there are other tags on the single closed outer way (like
highway=service or leisure=park), then this is an completely independent
object. In the case of leisure=park it would be equivalent to a second
multipolygon with these tags and only this single closed way as outer
member.
The situation you describe (multipolygon: natural=water; outer way:
leisure=park & natural=water), is a little ambiguous, though: In strict
interpretation, there would be 2 water areas. This is probably not the
intention, so I would consider natural=water on the outer way a legacy
artefact and ignore it.
Sebastian
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