[OSM-dev] Polygons and Multipolygons

[Artem Pavlenko]

On 8 Feb 2008, at 11:58, Richard Fairhurst wrote:

> Frederik Ramm wrote:
>
>> True. What we had been looking for was a term for "polygons with
>> holes"; it seemed unreasonable to create a relation "type=polygon" as
>> plain polygons, without holes, don't require relations. But
>> multipolygon is somewhat of a misnomer.
>
> It would be a "compound path" in Illustrator.

Yes, indeed. Rendering software (including Mapnik) doesn't really  
care about geometrical correctness, because rasterizing algorithms  
work just fine with self-intersections etc. The problems are start  
popping in when you want to do some kind of analysis, i.e. calculate  
a buffer zone for the river basin.

I'm for keeping OSM model as simple as possible, but not simplistic.

>
> cheers
> Richard
>

Cheers
Artem
> _______________________________________________
> dev mailing list
> dev at openstreetmap.org
> http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev