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

[Maarten Deen]

Martijn van Oosterhout wrote:
> 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.

Let me rephrase that: it should not be applied to non-closed ways?

>> 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...

It was an area where between some of the nodes there were two ways. And 
all the ways were tied together with a multipolygon.

So, nodes 1, 2, 3, 4, 5, 6, a way from 1-2-3-4-5-6-1, a way from 2-3-4, 
a way from 5-6-1, and all three ways together in a multipolygon.

Maarten