[OSM-talk] Intermittent rendering of multipolygons for buildings

Dan Karran dan at karran.net
Tue Feb 17 10:58:36 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

Is there a specific direction the ways have to go in on the outer and
inner parts of the relation? Can I use more than one inner part to the
relation to create holes? The wiki page at [2] suggests this should be
possible with multiple inner ways that don't necessarily have to point
in the same direction (though Mapnik may require the ways to go in
different directions).

Would be grateful for any insight.

[1] http://www.openstreetmap.org/?lat=51.50283&lon=-0.12689&zoom=17&layers=B000FTF
[2] http://wiki.openstreetmap.org/wiki/Relation:multipolygon


Dan Karran
dan at karran.net

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