well,... hm. Could you put this into trac so we don't lose it? Best would be in the GEOS trac, actually (http://trac.osgeo.org/geos) Once you get into really large tolerances, preserving topology starts to get problematic, for hopefully obvious reasons... I'm not sure how robust Martin's routines are supposed to be as tolerance gets really big. P.
This is a known design flaw in the SimplifyTP algorithm. The problem is that with large tolerance values small holes and shells can wind up on the "wrong side" of a containing geometry. It shouldn't be too hard to fix, just by checking whether holes/shells are outside/inside another shell, and deleting them if they are.
-- Martin Davis Senior Technical Architect Refractions Research, Inc. (250) 383-3022 _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users