Nathan, I have run into similar issues with complicated multipolygons rendering just find in Mapnik but not fine in Osmarender. Another mapper (who's area I had temporarily broken) told me that the member ways of my relations were in the wrong order. At the time I primarily used Potlatch which does not show an order for relation members. As far as I knew there was no order, or at least it didn't matter. As you know, Mapnik will render multipolygons correctly as long as all the ways form complete rings and are tagged with "outer" and "inner" as needed, but it turns out that Osmarender also needs the ways making up each ring to be in consecutive order. JOSM shows the order of the ways and it also shows when they are ordered consecutively in a ring.
On the multipolygon page of the wiki<http://wiki.openstreetmap.org/wiki/Multipolygon#Usage>it states that the order of the ways does not matter, but clearly to Osmarender it does. Either this is a bug in Osmarender or the wiki is wrong. If you look at my area of the map: http://www.openstreetmap.org/?lat=44.493&lon=-73.24&zoom=11&layers=M you'll see that the large lake (Lake Champlain) renders just fine in Mapnik, but switch to Osmarender and it looks like hell. This is most likely because the outer ways making up the multipolygon are in the "wrong" order. One of these days maybe I'll fix it, but I'd prefer it if Osmarender just behaved in the same way as Mapnik. Zeke Burlington, VT ---------- Forwarded message ---------- From: Nathan Edgars II <nerou...@gmail.com> To: talk@openstreetmap.org Date: Thu, 26 Aug 2010 22:10:09 -0400 Subject: [OSM-talk] What's wrong with this multipolygon? http://www.openstreetmap.org/?relation=1141252 Mapnik has no problems with it, but Osmarender won't fill the northern part correctly. (It's not a delay in rendering; I added the swamps after creating the multipolygon.)
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