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

[Martijn van Oosterhout]

On 11/3/07, Maarten Deen <mdeen at xs4all.nl> wrote:
> That is a bit terse. With an explanation like that I still don't know
> what it is good for (and judging from what I see on the map I'm not the
> only one). But Bart mailed me a good example which I think should be
> added to the wiki page about mulipolygon.
>
> Some observations:
> 1) it should not be applied to ways, only to areas?

An area is a closed way.

> 2) it should not be used to single areas that are contiguous?

Indeed.

> ex 1): I've seen multiploygons tying the left and right way of a
> motorway together, I assume that's false.

You're confusing relations with multipolygons. Not all relations are
multipolygons (if the tags are wrong they should be fixed, but a
relation is appropriate).

> ex 2): I've seen multipolygons applied to a natural=water where a lot of
> ways were double and they were connected with a multipolygon (making the
> T&H renderer do silly things)

Not sure which parts being double you are referring to so I can't
comment here...

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/