[postgis-users] View area

Wed Feb 16 11:35:49 PST 2005

The first statement works, and the 2nd does not.  

SELECT intersection(the_geom, intersection.the_geom)
As the_geom
>From counties
WHERE the_geom && intersection.the_geom;

SELECT intersection(the_geom, PolygonFromText(('3117737 1623703, 3117737
1692442, 3192501 1692442, 3192501 1623703, 3117738 1623703'),2332))
AS the_geom 
FROM counties
WHERE the_geom && PolygonFromText(('3117737 1623703, 3117737 1692442,
3192501 1692442, 3192501 1623703, 3117738 1623703'),2332);

////////
I've tried both:

PolygonFromText(('3117737 1623703, 3117737 1692442, 3192501 1692442,
3192501 1623703, 3117738 1623703'),2332)
&
PolygonFromText(LINESTRING'(3117737 1623703, 3117737 1692442, 3192501
1692442, 3192501 1623703, 3117738 1623703)',2332)

Examples are hard to come by, so I am not sure what the exact syntax
should be.  Shouldn't I be able to replace intersection.the_geom with
any valid polygon?  Why do I get "ERROR:  couldnt parse objects in
GEOMETRY"?

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Sean
M. Montague
Sent: Wednesday, February 16, 2005 11:55 AM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] View area

I'm not I understand what you mean by '*small* sql file'.  I'm using php
to query the database, and the select statement I sent is the only sql
statement I've used so far.  I've tried a different approach.  I created
a polygon in ArcView and imported it into PostGIS. The poly has about
the same coordinates as the BOX3D.  Below is the statement and it works
perfectly.

SELECT AsSVG(intersection(the_geom, intersection.the_geom),0,8)
As the_geom
>From counties
WHERE the_geom && intersection.the_geom;

-----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: Wednesday, February 16, 2005 10:38 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] View area

On Wed, Feb 16, 2005 at 10:23:30AM -0700, Sean M. Montague wrote:
> Strk, I really appreciate your help.  My geometries return valid, 't'.
> I've imported a new shape file, Colorado counties in StatePlane NAD83.
> Below is the full SQL statement I'm usisg.  I can send you the SQL
file
> for importing the table or the shape file itself if it'll help.

What would help is a *small* sql file containing a query like:

SELECT intersection('MULTIPOLYGON(((....)))', setSRID(...));

and giving unespected results.

Note that a intersection operation can return a collection of
points and triangles, depending on relation between the two geometries.

Also, make sure the SRID of geometries match .

--strk;

> 
> SELECT AsSVG(intersection(the_geom, setSRID('BOX3D(2705381 1688914,
> 2915183 1534212)'::box3d, 2332)),0,8) 
> AS the_geom 
> FROM counties 
> WHERE the_geom && setSRID('BOX3D(2705381 1688914, 2915183
> 1534212)'::box3d, 2332);
> 
> 
> -----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: Wednesday, February 16, 2005 10:07 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] View area
> 
> On Wed, Feb 16, 2005 at 10:00:45AM -0700, Sean M. Montague wrote:
> > I found a web site that said the version shipped with postgreSQL 8.0
> > installer had problems and linked to a windows installer for PostGIS
> > 0.9.1.  So I reloaded it, which is the version below.  I did get an
> > improvement, I think, but still have problems with intersection.  I
> > actually got polygons, but they don't resemble what actually exists.
> > Looks like they've been generalized into triangles, and some points
> were
> > still returned.
> > 
> > POSTGIS="0.9.1" GEOS="2.1.1" PROJ="Rel. 4.4.9, 29 Oct 2004"
USE_STATS
> > DBPROC="0.0.1" RELPROC="0.0.1"
> 
> Are you input geometries valid - check isvalid() ?
> Can you reproduce the *bug* with a single, full contained
> ( and possibly small ) sql script so I can take a look at it ?
> --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: Wednesday, February 16, 2005 1:23 AM
> > To: PostGIS Users Discussion
> > Subject: Re: [postgis-users] View area
> > 
> > On Tue, Feb 15, 2005 at 01:42:35PM -0700, Sean M. Montague wrote:
> > > I'm using postgreSQL 8.0.1 win32 version and whichever postGIS
comes
> > > with it, 0.9.1 I think.  My input geometries are multi-part
polygons
> > > imported from a shape file.  Every state is its own multi-part
poly,
> > > regardless of the number of individual polys, at least as a shape
> > file,
> > > not sure how postGIS handles this.  I'm also not sure what GEOS
I'm
> > > using.  Is this an add-on installed separately?
> > 
> > If intersection is working it's probably installed by the package
> > you got. Check output of SELECT postgis_full_version() to find
> > out the version.
> > 
> > --strk;
> > 
> > > 
> > > --Sean
> > > 
> > > -----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: Tuesday, February 15, 2005 1:33 PM
> > > To: PostGIS Users Discussion
> > > Subject: Re: [postgis-users] View area
> > > 
> > > On Tue, Feb 15, 2005 at 12:37:25PM -0700, Sean M. Montague wrote:
> > > > I've investigated what the relationship of the points is to the
> > > original
> > > > poly layer, and they are not the vertices, at least not all of
> them.
> > > > The original layer is the coast of south east Alaska with about
25
> > > > islands.  The points may be some of the vertices perhaps, they
do
> > lie
> > > on
> > > > the coasts.  The summary() returns 556 "Object 0 is a POINT()"
and
> 1
> > > > "Object 0 is a LINESTRING() with 2 points".  The up side is,
they
> at
> > > > least lie within my bounding box.
> > > 
> > > It sounds as a bug to me. Which GEOS version are you using ?
> > > What types are input geometries ?
> > > Which postgis version ? postgresql ?
> > > --strk;
> > > _______________________________________________
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