[postgis-users] Problem with functions contains

[Martin Davis]

It's quite possible this is just a rendering bug.  If that's the only
indication of a "bug in contains", then I would suspect the rendering
rather than the function itself.

The only real way to test this is to find the vertex or line segment
which lies outside the containing polygon. How about submitting the WKT?
(Not perfectly accurate I know, but at least a start)

Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046


> -----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: October 5, 2005 5:40 AM
> To: postgis-users at postgis.refractions.net
> Subject: Re: [postgis-users] Problem with functions contains
> 
> 
> I get the same results, but I can't "visually" see the 
> non-containment. I tried using qgis, but no displacement is 
> shown between the two boundaries until I zoom *really close* 
> obtaining a rendering bug instead. Can it be JUMP gets 
> confused as well by too-small values ?
> 
> --strk;
> 
> On Tue, Oct 04, 2005 at 06:09:57PM -0300, Miguel de la Fuente wrote:
> > strk: I' have the following problem, when I use the 
> function contains 
> > it returns true when the polygons is not totally contains. I have 
> > applied snaptogrid in my geometry column. I did the following :
> > update table1 set new_geom=snaptogrid(the_geom,1e-2)
> > update table2 set new_geom=snaptogrid(the_geom,1e-2))
> > When I use the function contains()
> >  select
> > b.*
> > from table2 b, table1 a
> > where contains (b.new_geom,a.new_geom)
> > it returns true,but I see visually that b not contains completely a.
> >  I don't understand why??
> >   I attach the data and a image showing the problem.
> >  Thanks.
> 
> 
> 
> 
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