[OSM-dev] Looking for guidance on interpreting multipolygon relations

bvh bvh-osm at irule.be
Sat Nov 3 08:55:04 GMT 2007


On Sat, Nov 03, 2007 at 10:10:55AM +0100, Frederik Ramm wrote:
> > Way A = outside of the park
> > Way B = inside of the park/outside of the lake
> > Way C/D = inside of the lake/outside of the island
> If you want to express that the water is a "hole" in the park, that
> would make two multipoly relations, one with outer=A inner=B, one with
> outer=B inner=C inner=D. Ideally the first relation would be tagged
> leisure=park and the second would be natural=water but currently you
> would be expected to tag the ways themselves (leading to double
> tagging for B).

I disagree violently with the double tag
- double work
- impossible when conflicting tags for example leisure=garden inside
a leisure=park.
- does not specify which tag is for the inside and which tag for the outside
- does not add anything. my proposal to tag only the outside role gives
more information in a non-ambigious way.

> > A: leisure=park
> > B: natural=water?
> > C/D: leisure=park?
> If you are of the opinion that the *whole* forms a park - i.e. if you
> would say the lake is part of the park rather than an area where the
> park stops - then I would advise tagging way A as "leisure=park" (this
> area does not have a hole then - do not use relations) and use one
> relation with outer=B inner=C inner=D tagged natural=water for the
> lake.

And how would a renderer know that it has to render the first relation
before the second relation? Not with layers I hope because then we
are back where we started.

cu bart




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