[OSM-talk] Best way to draw areas with holes?

[Rahkonen Jukka]

Dave Stubbs wrote: 

On 20/12/2007, Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi> wrote:

>> Hi,
>>
>> Some area features would be drawn in GIS world as polygons with holes but
>> that is not well supported by OSM data model.  I mean, for example, landuse
>> which has islands with some other landuse or big buildings having inner
>> courts or patios.  I have seen that users have solved this in many
>> innovative ways but most of them seem to lead to more or less odd rendering
>> at least in case of buildings.  Is there any recommended way to draw and tag
>> this kind of objects?  To draw an area in the halves, or delineate a
>> building as a fat loop sharing some points at a seem (non-existing in real
>> world) to make it look like a closed area, or what?

> Use the multipolygon relation.
> It'll be rendered by the Mapnik layer at least.
> http://wiki.openstreetmap.org/index.php/Relations/Multipolygon

> Unfortunately you can't do that in Potlatch yet, so you'll need to be
> using JOSM or some other editor which supports relations.


Thanks, I will learn to use that.

-Jukka-