Leo/Paul, Indeed, a bunch of polygons (900) of wich I need the outline. In fact drawing one line around the objects.
I tried st_union but this returns an empty result. st_exteriorRing returns lines from polygons but still the same number of objects. Might be close to it but I'm still struggling with it. Ge --- On Thu, 8/13/09, Paragon Corporation <[email protected]> wrote: > From: Paragon Corporation <[email protected]> > Subject: Re: [postgis-users] how to create ouline of multiple objects > To: "'PostGIS Users Discussion'" <[email protected]> > Date: Thursday, August 13, 2009, 11:54 AM > Ge, > > What do you mean by outline of all objects? You > mean if you have a bunch > of polygons you just want one record with all boundaries > dissolved? > > Maybe you are looking for ST_Union > > SELECT ST_Union(the_geom) > FROM sometable > > That will dissolve boundaries. > http://postgis.refractions.net/documentation/manual-svn/ST_Union.html > > or you mean you have a polygon and you want the linestring > outline. > > For that use ST_Boundary(the_geom) or ST_ExteriorRing > http://postgis.refractions.net/documentation/manual-svn/ST_Boundary.html > > http://postgis.refractions.net/documentation/manual-svn/ST_ExteriorRing.html > > > > Leo > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] > On Behalf Of G. van > Es > Sent: Thursday, August 13, 2009 2:48 PM > To: PostGIS Users Discussion > Subject: [postgis-users] how to create ouline of multiple > objects > > Hi All, > > Maybe a stupid question but I have a shape imported in PG > of wich I want to > determine the outline of all objects. The result should be > a LINE or just > one POLYGON. > > Does anyone know if this is possible in PG. > > Thanks, > > Ge > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
