[postgis-users] query question

[Nicolas Ribot]

2009/11/5 G. van Es <gves2000 at yahoo.com>:
> Thanks Maxime,
>
> That worked!
>
> However now I see another problem.
>
> Some polygons are touching in a way they shouldn't. This is a problem of our drawing department but since there are a few thousand of those objects it would be nice to query with a certain tolerance. Say, the object should overlap for at least 80%.
>

Hello,

You could compute the actual intersection (st_intersection) area and
compare its area to the initial polygons area

Nicolas

> Well, that is too much rocket science for me at the moment.
> If someone has any clue if this is possible please drop me a line.
>
> Thanks,
> Ge
>
> --- On Wed, 11/4/09, Maxime van Noppen <maxime at altribe.org> wrote:
>
>> From: Maxime van Noppen <maxime at altribe.org>
>> Subject: Re: [postgis-users] query question
>> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>> Date: Wednesday, November 4, 2009, 3:56 AM
>> G. van Es wrote:
>> > I want to have a list of wich geometry of a certain
>> type is touching or crossing another type.
>> >
>> > Can someone point me in the right direction?
>>
>> Hi,
>>
>> If I understand your problem you want to find for each
>> geometry in your
>> table which geometries intersect with it ?
>>
>> This can be done with the ST_Intersects function and an
>> self-join.
>> Something like :
>>
>> SELECT t1.type, t2.type FROM T t1, T t2 WHERE t1.type !=
>> t2.type AND
>> ST_Intersects(t1.the_geom, t2.the_geom);
>>
>> This will generate an output like :
>>
>> t1.type | t2.type
>> -----------------
>> 13      | 12
>> 13      | 1
>> 13      | 4
>> 12      | 3
>> 12      | 8
>> ...
>>
>> --
>> Maxime
>> _______________________________________________
>> postgis-users mailing list
>> 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
>