[postgis-users] Re: PG 8.0 and PostGIS 1.0 RC1onWindows2003overlap

[Randy George]

Hi,

	This is interesting:
select AsEWKT(transform(SetSRID('BOX3D(284519.3 3769952.1,496251.69999999995
3596407.1)'::box3d, 26712),4269));
returns: "SRID=26712;POLYGON((-113.293160109785
32.4857520041516,-113.334429907594 34.0498920281307,-111.040622350418
34.0720603897317,-111.039903423973 32.5066459734368,-113.293160109785
32.4857520041516))"
I guess the transform doesn't reset the SRID even though it correctly
transforms the geometry?

Is there any efficiency savings by using Box3d casting?

Thanks
Randy


-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
strk at refractions.net
Sent: Thursday, January 27, 2005 10:31 AM
To: 'PostGIS Users Discussion'
Subject: Re: [postgis-users] Re: PG 8.0 and PostGIS 1.0
RC1onWindows2003overlap

On Thu, Jan 27, 2005 at 10:12:49AM -0700, Randy George wrote:
> Hi 
> 
> 	I just installed  PG 8.0 and PostGIS 1.0 RC2 on a Windows 2003
> server
> 
> 	When attempting the old query on my test data:
> 
> select id, type as name, AsText(the_geom) from ibus where type='SOR' and
> the_geom && transform(GeometryFromText('BOX3D(284519.3
> 3769952.1,496251.69999999995 3596407.1)'::box3d,26712),4269);
> 
> I get: ERROR:  function geometryfromtext(box3d, integer) does not exist
> 
> Replacing Box3D with LineString:
> 
> select id, type as name, AsText(the_geom) from ibus where type='SOR' and
> the_geom && transform(GeometryFromText('LineString(284519.3
> 3769952.1,496251.69999999995 3596407.1)',26712),4269);
> 
> Since the bounding box is the same as the BOX3D but Linestring is a text
> this gives the correct result.
> 
> 
> I was looking through the docs for some more information on Box3D but I'm
> not clear when/how use of Box3D would be appropriate?
> 
> Is 'BOX3D(284519.3 3769952.1,496251.69999999995 3596407.1)'::box3d a
> shortcut for creating a bounding box geometry only when SRID is not an
> issue? Or is there a way to transform a Box3D to a new SRID?
> It is used in the examples Re: 4.6.1 in new docs

A BOX3D has no SRID. When using the && operator your box is being
transformed to a GEOMETRY by an implicit cast. If you need to 
specify a SRID other then -1 you must use the SetSRID(geometry, int)
function. Again, you will rely on an implicit cast doing:

	SetSRID('BOX3D(...)'::box3d, 4326)

I hope this wasn't too confusing.

--strk;


> 
> Thanks
> randy
> 
> 
> 
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Mark
> Cave-Ayland
> Sent: Tuesday, January 25, 2005 3:04 AM
> To: 'PostGIS Users Discussion'
> Subject: RE: [postgis-users] Re: PG 8.0 and PostGIS 1.0
> RC1onWindows2003overlap
> 
> Hi strk,
> 
> > -----Original Message-----
> > From: postgis-users-bounces at postgis.refractions.net 
> > [mailto:postgis-users-bounces at postgis.refractions.net] On 
> > Behalf Of strk at refractions.net
> > Sent: 25 January 2005 09:25
> > To: Mark Cave-Ayland
> > Cc: 'PostGIS Users Discussion'
> > Subject: Re: [postgis-users] Re: PG 8.0 and PostGIS 1.0 
> > RC1onWindows2003overlap
> > 
> > 
> > Mmm.. I wouldn't use GeometryFromText with a BOX3D argument.
> > I think it should only accept 'text' as it has been done with 
> > GeomFromWKB only accepting bytea.
> 
> No complaints here. We do a lot of queries like "the_geom && BOX3D('1 2 3,
4
> 5 6')" (and I believe the Mapserver connector uses a similar query) so as
> long as these still work, I can live without accepting BOX3D as part of
> GeometryFromText().
> 
> > Beside this, you can use asEWKT(geometry) to see Extended WKT.
> 
> That's the function I couldn't remember then :)
> 
> > .. And .. I've found the bug.
> > The transform() functoin is failing to transform/recompute an 
> > already cached bbox.
> > 
> > I'm working on it.
> 
> Just got your patch, but having Windows/Linux conversion problems ;) Will
> try and find a moment to test it at this end later.....
> 
> 
> Kind regards,
> 
> Mark.
> 
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