[OSM-talk] Intermittent rendering of multipolygons for buildings

Michael quelbs+osm at gmail.com
Tue Feb 17 11:51:06 GMT 2009


>> I'm trying to render some buildings with holes in and using
>> multipolygon relations to do it, but they don't always render. See,
>> for example Whitehall[1], where the HMRC/Treasury building is rendered
>> with its holes but the Foreign Office building to the north of it
>> doesn't have its multiple holes rendered, nor does the smaller
>> building to the east of this which only has one inner and one outer
>> part.
>>
>> Would be grateful for any insight.
>>     
>
> Mapnik seems to have trouble with more than one hole.
> if you look closely the HMRC/Treasury is not mapped as one, but two
> buildings, each with one hole.
>
> As to the building to the east, I don't know.
>   
For me also buildings with multiple holes work fine, but only when the
outer part goes clockwise and the inner parts go anticlockwise and are
without any tag. Even with a created_by tag the holes had not been
created for this example
<http://www.openstreetmap.org/?lat=48.139768&lon=11.549817&zoom=17>.
Without any tags in the inner parts the holes appeared.
The created_by tags of the inner parts in example [1] may be the problem.

Cheers,
Michael




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