Oops, sorry, wrong language... Hi Andreas,
I'm also interested in this topic from a quality assurance point of view (identification of impossible/invalid overlaps). We could exchange our ideas and experiences here. However, I'm using Postgres/POstGIS, which has a richer set of geometry functions and is also the database of choice for osm. The multipolygon structure (inner/outer) is relatively simpel, nested multipolygons are still to be looked at (depending on what's actually tagged and whether it's worth the effort). There are functions in PostGis that detect invalid geometries (which need to ben ignored, including most of the old-style balloon multipolygons), programming that yourself promises to be rather painful. Have you already taken a look at the OGC spec (http://www.opengeospatial.org/standards/sfa)? IMHO this will be the first standard that osm will find impossible to ignore, provided is takes it self seriously. Best regards Wolfgang _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev

