[postgis-users] Bug dropping the Z coordinate?

[Paragon Corporation]

As a side note.  ST_Zmax doesn't exist for geometries.  It works because
geometries can be autocast to boxes.

See matrix
http://www.postgis.org/documentation/manual-svn/ch08.html#PostGIS_TypeFuncti
onMatrix 

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Paragon
Corporation
Sent: Sunday, January 10, 2010 10:50 PM
To: 'PostGIS Users Discussion'
Subject: Re: [postgis-users] Bug dropping the Z coordinate?

Abe,

It seems we are flattening the box3d geometry in to a 2D polygon always
instead of as a 3D/2.5D polygon. 
I'm not sure it's a bug though, because I think a box3d is an invalid 2.5/3D
polygon if you were to construct it.

Can you envision it?

Paul, Mark or Kevin might have a better clue, but I think it's at best an
ambiguous 3D polygon and that is the problem. A box3d isn't really a 3D box,
its more just a coordinate bounding thing.

Hope that helps,
Regina

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Abram
Gillespie
Sent: Sunday, January 10, 2010 4:31 PM
To: PostGIS Users Discussion
Subject: [postgis-users] Bug dropping the Z coordinate?

Is this a bug?

select ST_ZMax('BOX3D(0 0 0,0 0 1)'::box3d);

versus

select ST_ZMax(ST_GeomFromEWKB(ST_AsEWKB('BOX3D(0 0 0,0 0 1)'::box3d)));

The first query returns "1" as expected but the second returns "0" as
unexpected.

I'm trying to add Z/M support to zigGIS and this is show-stopping me.
Any work-arounds if this is a bug?  Also, I'll be happy to report the bug if
so.

Thanks.
-Abe
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