[postgis-users] FW: Support in ST_ConvexHull syntax

Gery . gamejihou at hotmail.com
Thu Oct 20 05:09:01 PDT 2011



or should be 3 in my table! Bingo! after running: "select st_ndims(st_convexhull(st_collect(geom)) from splitbeam_point;" I got 3 instead of 2, so I put this3 into my table and ready! that did the trick. Now I'm wondering why this has to be 3, I mean, this is a 2D polygon, I think I'll realize that after keeping reading.

Thanks again Sandro, you were very helpful,

Cheers,

Gery
 

> Date: Thu, 20 Oct 2011 11:53:27 +0200
> From: strk at keybit.net
> To: gamejihou at hotmail.com
> CC: postgis-users at postgis.refractions.net
> Subject: Re: [postgis-users] FW: Support in ST_ConvexHull syntax
> 
> On Thu, Oct 20, 2011 at 09:26:48AM +0000, Gery . wrote:
> 
> > mop=# \d unaprueba
> >    Table "public.unaprueba"
> >  Column |   Type   | Modifiers 
> > --------+----------+-----------
> >  id     | smallint | 
> >  geom   | geometry | 
> > Indexes:
> >     "unaprueba_geom" gist (geom)
> > Check constraints:
> >     "enforce_dims_geom" CHECK (st_ndims(geom) = 2)
> >     "enforce_geotype_geom" CHECK (geometrytype(geom) = 'POLYGON'::text OR geom IS NULL)
> >     "enforce_srid_geom" CHECK (st_srid(geom) = 4326)
> 
> ...
> 
> > mop=# insert into unaprueba (geom) SELECT st_convexhull(st_collect(geom)) as geom FROM splitbeam_point ;
> > ERROR:  new row for relation "unaprueba" violates check constraint "enforce_dims_geom"
> > 
> > where could be the problem?
> 
> << The new row violates check constraint "enforce_dims_geom" >>
> 
> Compare the above message with the output of \d above:
> 
> > Check constraints:
> >     "enforce_dims_geom" CHECK (st_ndims(geom) = 2)
>       ^^^^^^^^^^^^^^^^^^^
> >     "enforce_geotype_geom" CHECK (geometrytype(geom) = 'POLYGON'::text OR geom IS NULL)
> 
> Check the output of:
> 
>   st_ndims(st_convexhull(st_collect(geom)) from splitbeam_point;
> 
> Must be 2 ...
> 
> --strk; 
> 
>   ()   Free GIS & Flash consultant/developer
>   /\   http://strk.keybit.net/services.html
 		 	   		  
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