[postgis-users] query question

[G. van Es]

Good call!
With the following partial statement we get promising results.

round(st_area(st_intersection(r.the_geom,s.the_geom)) / st_area(r.the_geom) * 100) as Percentage


Thanks,
Ge

--- On Thu, 11/5/09, Nicolas Ribot <nicky666 at gmail.com> wrote:

> From: Nicolas Ribot <nicky666 at gmail.com>
> Subject: Re: [postgis-users] query question
> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
> Date: Thursday, November 5, 2009, 12:45 AM
> 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
> >> _______________________________________________
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> >> postgis-users at postgis.refractions.net
> >> http://postgis.refractions.net/mailman/listinfo/postgis-users
> >>
> >
> >
> >
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