[postgis-users] Problem with ST_WITHIN

[Luigi Castro Cardeles]

Hi list and Martin,

If i use st_covers, the query 1 and 2 return's false.
After read the blog, i am thinking that covers should return true at that
cases.
query 1:
select ST_covers
    (
        geomfromtext('LINESTRING(10 18, 30 18)',4326),
        geomfromtext('MULTIPOLYGON (((10 18,30 18,30 12,10 12,10
18)))',4326)
    )

and

query 2:
select ST_covers
    (
        geomfromtext('POINT(10 18)',4326),
        geomfromtext('MULTIPOLYGON (((10 18,30 18,30 12,10 12,10
18)))',4326)
    )


select postgis_full_version();
"POSTGIS="1.3.6" GEOS="3.1.0-CAPI-1.5.0" PROJ="Rel. 4.6.1, 21 August 2008"
USE_STATS"
I am using postgres 8.3.7 version and windows vista os.

I read the release notes and the bug tracker and don't find any bug that fit
the problem.

In the meanwhile, i will download the postgres 8.3.8, 8.4.1 and try with
newer versions of postgis 1.4.0 etc.

Anyone has any clues?

very thanks for yout help,
Luigi Castro Cardeles


2009/9/21 Martin Davis <mbdavis at refractions.net>

> The OGC definition for Contains and Within have always seemed a bit
> non-intuitive to me.  They may be theoretically elegant. but they don't
> really address the most common use case.   (See a blog post on this as:
> http://lin-ear-th-inking.blogspot.com/2007/06/subtleties-of-ogc-covers-spatial.html).
>
>
> That's why JTS, GEOS and PostGIS define the covers() predicate, which has
> simpler, more intuitive and more practical semantics.
>
> http://postgis.refractions.net/documentation/manual-1.4/ST_Covers.html
>
>
> Luigi Castro Cardeles wrote:
>
>> Hi list and Chris,
>>
>> this is what i was asking :D
>>
>> i was thinking that boundary is part of the geometry, so if there is some
>> geometry on the boundary (in this case, a point on the polygon boundary)
>> then the point is within the polygon. But after your message i read the
>> specs (http://portal.opengeospatial.org/files/?artifact_id=18241) about
>> within, i see the relate and now i understand. Thanks for the hint Chris.
>>
>> []'s
>> Luigi Castro Cardeles
>>
>>
>> 2009/9/18 Chris Hermansen <chris.hermansen at timberline.ca <mailto:
>> chris.hermansen at timberline.ca>>
>>
>>    If it's on the boundary, is it within?
>>    Chris Hermansen        chris.hermansen at timberline.ca
>>    <mailto:chris.hermansen at timberline.ca>
>>    tel+1.604.714.2878 · fax+1.604.733.0631 · mob+1.778.840.4625
>>    Timberline Natural Resource Group · www.timberline.ca
>>    <http://www.timberline.ca>
>>    401 · 958 West 8th Avenue  · Vancouver BC · Canada · V5Z 1E5
>>
>>
>>    -----Original Message-----
>>    From: Luigi Castro Cardeles <luigi.cardeles at gmail.com
>>    <mailto:luigi.cardeles at gmail.com>>
>>
>>    Date: Fri, 18 Sep 2009 10:01:32
>>    To: PostGIS Users Discussion<postgis-users at postgis.refractions.net
>>    <mailto:postgis-users at postgis.refractions.net>>
>>    Subject: Re: [postgis-users] Problem with ST_WITHIN
>>
>>
>>    _______________________________________________
>>    postgis-users mailing list
>>    postgis-users at postgis.refractions.net
>>    <mailto:postgis-users at postgis.refractions.net>
>>    http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>>    _______________________________________________
>>    postgis-users mailing list
>>    postgis-users at postgis.refractions.net
>>    <mailto:postgis-users at postgis.refractions.net>
>>    http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>>
>
> --
> Martin Davis
> Senior Technical Architect
> Refractions Research, Inc.
> (250) 383-3022
>
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20090921/2e4227ef/attachment.html>