Hi Bruce, Could you give a sense of what you want to cluster and what your objective is with respect to the use of the clustering results? There are a lot of clustering methods out there, so knowing a bit about what you want to accomplish would help.
Dan On Tue, 2008-09-09 at 11:13 -0400, Clay, Bruce wrote: > I am trying to use GDAL to cluster a group of points. I am creating a > buffer around the points then testing buffered points for > intersection. I am putting those that intersect into a > GeometryCollection then creating a convexHull to smooth the polygon. > > > > All of that works ok but the problem is that the resultant polygon is > larger than is desired because of the buffer used to create the > intersections. > > > > I tried to use a negative value with the Geometry Buffer method to > shrink the polygon back down to the proper size but Buffer always > returns a NULL pointer. I stepped down into the call and it looks > like GEOS is returning a valid geometry but OGR rejects the polygon do > to the number of points being too low. The initial buffer size is 1.5 > Km so smallest cluster has a minimum spatial diameter of 3 km. I saw > point counts in the debugger of over 2000 so I am not sure why OGR > appears to reject the geometry that GEOS passed back. I don’t have > GEOS compiled with debug turned on so I could not step into that > > > > Is there another way to reduce the size of a polygon or a smarter war > to cluster points? > > > > Bruce > > > > > > > > > > This message and any enclosures are intended only for the addressee. Please > notify the sender by email if you are not the intended recipient. If you are > > not the intended recipient, you may not use, copy, disclose, or distribute > this > message or its contents or enclosures to any other person and any such > actions > may be unlawful. Ball reserves the right to monitor and review all messages > and enclosures sent to or from this email address. > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Dan Putler Sauder School of Business University of British Columbia _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
