[postgis-users] geos result sets

[Paul Ramsey]

Can you give us a picture of your scenario? Asserting that ArcView is 
"right" does not aid the debugging process. Probably the issue is one 
of semantics around the OpenGIS predicates (we really need to write up 
a page of description with pictures ... )
P.

On Tuesday, February 24, 2004, at 08:20 AM, James S reid wrote:

> not disjoint() is worse!! in case its my sql heres the query :
>
> test=# select nuts3.* into temp from nuts2,nuts3 where not
> disjoint(nuts3.the_geom,nuts2.the_geom) = TRUE and nuts2=2;
>
> essentially Ive two tables and im tryinbg to sd a polygon in polygon
> selection - arcview correctly brings back 8 records - the above brings 
> 15!!
>
> my original with within() qurey looked like:
>
> test=# select nuts3.* into temp from nuts2,nuts3 where
> within(nuts3.the_geom,nuts2.the_geom) = TRUE and nuts2=2;
>
> this brought 7 polys back - 1 less than AV and I cant figire out my it
> dislikes it !! BTW - reversing the tables and using a contains() also 
> brings
> back 7 polys so I think its something in the geos computation??
>
> however - my SQL may be naive so if anyone can correct me Id 
> appreciate it
> :)
>
> regards
>
> james
>
> ----- Original Message -----
> From: "Paul Ramsey" <pramsey at refractions.net>
> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
> Sent: Tuesday, February 24, 2004 3:50 PM
> Subject: Re: [postgis-users] geos result sets
>
>
>> The definition of Within() is not what you think it is.
>> Try using "Not Disjoint()".
>> P.
>>
>> On Tuesday, February 24, 2004, at 06:59 AM, James S reid wrote:
>>
>>> further to my eralier queries, Ive been doing some experimenting - i
>>> consistently get less polys that Im convinced i should using the
>>> within() operator on 2 tables (mr ESRI agrees with me) - so either 
>>> the
>>> geos computation is wrong, arcview is wrong or theres some subtlety 
>>> in
>>> the precision that im missing.
>>>
>>> has anyone else noticed weird things going on?
>>>
>>> Postgis 0.8.0/1 pg 7.4.1 geos 1.0 cywin environment
>>>
>>>
>>> regards
>>>
>>> james
>>> Edinburgh
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>
>>       Paul Ramsey
>>       Refractions Research
>>       Email: pramsey at refractions.net
>>       Phone: (250) 885-0632
>>
>> _______________________________________________
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>
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      Paul Ramsey
      Refractions Research
      Email: pramsey at refractions.net
      Phone: (250) 885-0632