Thanks Brent. I'm looking for a C/C++ solution. I'll take a look at the other polygon processing libraries as well as the level of effort in porting JTS Cascaded Unions to Geos... that's a conversation for a different mailing list though.
Craig -----Original Message----- From: Brent Fraser [mailto:[EMAIL PROTECTED] Sent: Friday, August 29, 2008 7:53 AM To: Craig Miller Cc: [email protected] Subject: Re: [gdal-dev] Topological Union? Craig, I've had limited success with the Union function in Geos (via GDAL). It's slow and fails on large polygon sets (some of my files have 10,000 polygons with some convoluted geometry), but if your sets are smaller, it may work. FYI, Geos is derived (ported?) from JTS; Martin Davis has a good explanation of union strategies at http://lin-ear-th-inking.blogspot.com/2007/11/fast-polygon-merging-in-jts-using.html. Currently, I'm considering using Geotools (http://geotools.codehaus.org/) as a framework to get at the JTS functionality. And there are other polygon processing libraries out there. There's a nice summary at http://www.complex-a5.ru/polyboolean/comp.html, but I haven't tried any of those yet. Good Luck! Brent Fraser Mateusz Loskot wrote: > Craig Miller wrote: >> Thanks Mateusz. That's exactly what I was thinking of doing if >> someone hasn't put it together already. > > Craig, > > BTW, you don't have to convert OGRGeometry (you play with it when > reading Shapefile using OGR) to geos::geom::Geometry. > > You can union OGRGeometry using OGRGeometry::Union() > or its C API equivalent OGR_G_Union > > These operations are based on GEOSUnion function. > > Best regards, No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.169 / Virus Database: 270.6.13/1641 - Release Date: 8/29/2008 7:07 AM _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
