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List:       postgis-users
Subject:    Re: [postgis-users] ST_Envelope
From:       "Paul Ramsey" <pramsey () cleverelephant ! ca>
Date:       2008-04-22 14:54:45
Message-ID: 30fe546d0804220754w2272d75u6a9cd4870ebd3a63 () mail ! gmail ! com
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doco patched

On Tue, Apr 22, 2008 at 4:45 AM, Mark Cave-Ayland
<mark.cave-ayland@siriusit.co.uk> wrote:
> Sam Giffney wrote:
>
> > On Postgis 1.3.2 (tested on Windows and Debian Lenny)
> >
> > A LINESTRING which runs "parallel to the grid lines" (excuse my poor
> > GIS terminology) returns a LINESTRING instead of a POLYGON for the
> > envelope.
> >
> > postgis=> select
> > ST_AsText(ST_Envelope(ST_GeomFromText('LINESTRING(-36.91410
> > 174.90900,-36.91410 174.91017)')));
> >                    st_astext
> > -------------------------------------------------
> >  LINESTRING(-36.9141 174.909,-36.9141 174.91017)
> > (1 row)
> >
> > The documentation states that ST_Envelope should return a POLYGON.
> > I think I understand why the LINESTRING is returned, but shouldn't the
> > documentation list that as an option?
> >
> > Cheers,
> > Sam
> >
>
>
>  Hi Sam,
>
>  It is the documentation that is wrong. The change was made in order to
> ensure that only valid geometries can be returned from the ST_Envelope() /
> bounding box functions. See
> http://postgis.refractions.net/pipermail/postgis-commits/2007-October/000180.html
> for more information. Any doc patches gratefully received :)
>
>
>  ATB,
>
>  Mark.
>
>  --
>  Mark Cave-Ayland
>  Sirius Corporation - The Open Source Experts
>  http://www.siriusit.co.uk
>  T: +44 870 608 0063
>
>
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