[Tilesathome] Extended Multipolygon support

[Hermann Kraus]

On Tue, 03 Mar 2009 10:03:27 +0100, Dirk Stöcker  
<openstreetmap at dstoecker.de> wrote:
> Touching inner polygons are different. When I implemented inner polygons  
> I
> thought that is not necessary, but creating e.g. the wood with beach and
> water inside without touching requires a very complicated way of tagging
> the ways (which BTW is not yet supported by JOSM, as JOSM uses every way
> once only). 3 different inner ways and 2 inner multipolygons compared to  
> 2
> inner touching ways, so that from my point of view touching inner ways  
> are
> a must have (if the have different features only).

Touching inner ways are supported, as long as the either consist of one  
closed way, or if (for large inner ways) the split is at a node that isn't  
shared. If three or more _unclosed_ ways start or end at the same node the  
combining algorithm fails. But I don't see how this could be solved.

> I wait for the day when both renderers implement the advanced
> multipolygons well and I can start warning about tagged outer ways :-)

I had a look at osm2pgsql and it looks like it already supports tagging in  
the relation. So after this patch is applied both renderers would support  
tagging the relation and you can add this check.

I'm quite happy the validator does no longer warn about untagged inner  
ways for multipolygons. It would be even better if it also wouldn't  
complain about untagged nodes for label-relations, but that's another  
story.


Hermann