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

Frederik Ramm frederik at remote.org
Sat Nov 3 09:10:55 GMT 2007


Hi,

> So, how should multipolygon relations really work?

I'll give you my idea of how they should work, no idea what others
think.

> Let's start with a simple example : a park with a lake and a few
> islands in that lake. (Battersea Park in Londen 51.4805/-0.153808)
> 
> 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).

> 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.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'





More information about the dev mailing list