I wound up using Spatialite (SQLite + WKB/GEOS support) instead of writing my own code. It was very fast and easy to setup. It would make a perfect teaching/learning tool for anyone who wants to learn about SQL and spatial operators.
Craig -----Original Message----- From: Mateusz Loskot [mailto:[EMAIL PROTECTED] Sent: Friday, August 29, 2008 10:22 AM To: Craig Miller; Craig Miller Cc: 'Brent Fraser'; [email protected]; 'Brent Fraser'; [email protected] Subject: Re: [gdal-dev] Topological Union? Craig Miller wrote: > 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, I agree with Brent that performance is/may not be very impressive. In OGR, this is mostly caused by a need to convert OGRGeometry type to GEOS geometry type [1] - allocating & copying coordinates data is expansive. However, if you are developing your own solution in C++, you can avoid this by defining your geometry in terms of interface of geos::geom::Geometry or - following design pattern called adapter, you can provide a thin wrapper on your geometry type that will make it accessible to GEOS engine. This way you should get rid of major bottleneck of OGR<->GEOS interoperability. [1] http://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogrgeometry.cpp#L2105 Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
