Try this. Select ST_ConcaveHull(ST_Collect(the_geom)) FROM table;
*--------------------------------------------------------------------------- Ahmad Aburizaiza PhD student at **George Mason University** Geography and Geoinformation Science Department Fairfax, VA, USA Tel : +1-703-981-0354* On Thu, Jul 7, 2011 at 10:44 AM, Brian Sanjeewa Rupasinghe < [email protected]> wrote: > Hi, > > I have a building polygon table and from the following query i get the > polygon > coordinates. > > select st_astext (st_geometryn(the_geom, 1)) > from building_poly; > > Now what i need is to get the concave hull of all polygon coordinates. > I tried the following query but it does not work. > > SELECT ST_ConcaveHull(ST_Union(select st_astext (st_geometryn(the_geom, > 1)) > from building_poly), 1) As convexhull; > > How to correct it? > > Cheers, Sanjeewa. > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > >
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