On Thu, May 13, 2010 at 09:22:49AM -0700, Martin Davis wrote: > Just tried the buffer-and-union approach in JTS. It works fine - about > 70 s for the union, less for the initial buffering. Memory usage was low.
I tried buffer-and-union approach in PostGIS. It was very fast ! Some stats: - Original geometry is a MULTILINESTRING with 3272 components - Average number of points per component: 3.3 (from 2 to 93) - Total number of points: 10677 Postgis operations with timing: $ time psql -c 'create table bug_dump2 as select (st_dump(g)).* from bug;' real 0m0.330s user 0m0.032s sys 0m0.012s $ time psql strk -c 'update bug_dump2 set geom = st_buffer(geom, 0.005)'; UPDATE 3272 real 0m0.463s user 0m0.040s sys 0m0.008s $ time psql strk -Ac 'select st_npoints(st_union(geom)) from bug_dump2'; st_npoints: 1336 real 0m1.181s user 0m0.040s sys 0m0.008s This is postgis trunk (to be 2.0.0) with GEOS trunk (to be 3.3.0). I'm surprised it takes 70 seconds with JTS. Am I doing anything wrong here ? --strk; () Free GIS & Flash consultant/developer /\ http://strk.keybit.net/services.html _______________________________________________ geos-devel mailing list geos-devel@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/geos-devel