[OSM-talk] help with multipolygons

[Ulf Mehlig]

I'm trying to make a map of coastal vegetation in north Brazil:

http://www.openstreetmap.org/?lat=-0.92649&lon=-46.66564&zoom=16&layers=B000FTF

I used multipolygons to specify adjacent wetland types (natural=wetland
+ wetland=mangrove/wetland=marsh) and neighbouring terrestrial forest,
tagging the relations, not the ways. Terrestrial forests are on
"islands" within marshes and mangroves (the mapnik map of
www.openstreetmap.org does not differentiate between wetland=marsh and
wetland=mangrove).

The rendering on the main site works somehow, but, for example, the
south-eastern forest
islands and surrounding marshes receive an extra cover of the wetland
pattern. Unfortunately, I haven't been able to figure out the error.

Does anybody see whether this is a tagging/relation-building error of
mine, or whether this is just due to limitations of the current
renderers? I think it might be rather a rendering problem, because
mapnik gets it apparently right on my computer (see attached PNG tile).

Thanks for your help!
Ulf


-- 
 Ulf Mehlig <ulf.mehlig at gmx.net>
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