[postgis-users] ST_ConcaveHull

[Denis Rykov]

Simple,
Select ST_ConcaveHull(ST_Union(the_geom),99) FROM  building_poly As convexhull;

On Thu, Jul 7, 2011 at 2:44 PM, Brian Sanjeewa Rupasinghe
<jinkabs at gmail.com> 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.
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