Hi postgis-user, i like to get the difference between n crossing exterior Linerings and n smaller polygons which are within the rings. In Quantum GIS everything works as aspected.
Scenario: LineRing A ________ (________) LineRing B ________ (________) Situation between A and B ______________ (_____(__)_____) Two smaller Polygons within the Linerings to erase the shared part of LineRing A and B. If i first use ST_Union to dissolve the Polygon Geometry everything works fine with st_difference, but ST_UNION is no option for a dataset > 4 million. With the following SQL-Statement, i can extract the shared parts. Select (st_dump(st_intersection(a.geom,b.geom))).geom as geom from line b, poly a where st_intersects(a.geom,b.geom) But how to keep on? I'm stuck. BIG THANKS for any kind of assistance! Simon _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
