[postgis-users] ST_Insersection problem

[G. van Es]

I'm interested in the area of the intersection so a boolean answer will not do. The example query is the one I use to prevent my screen from filling with a few hundred-thousands records.

I have simplified all geometries to POLYGON (no MULTI, no Collection), still st_intersection crashes.

My conclusion that it is a bug either in PG or GEOS, which also is mentioned in the manual.


So for any idea about a workaround I would be very happy to know about it.

Ger




________________________________
From: Sandro Santilli <strk at keybit.net>
To: G. van Es <gves2000 at yahoo.com>; PostGIS Users Discussion <postgis-users at postgis.refractions.net>
Sent: Tuesday, September 20, 2011 2:14 PM
Subject: Re: [postgis-users] ST_Insersection problem

On Tue, Sep 20, 2011 at 03:45:49AM -0700, G. van Es wrote:

> Given the following query
> select count(st_intersection(tbl_a.the_geom,tbl_b.the_geom)) from tbl_a, tbl_b;
> 
> will result in this error message
> 
> NOTICE:  TopologyException: found non-noded intersection between LINESTRING (62723.7 426635, 62722.5 426634) and LINESTRING (62723.7 426635, 62726.2 426632) at 62723.7 426635
...
> Does anyone know a solution or workaround for this problem?

If that's the real query you're needlessly requesting computation of
the intersection space, which is having robustness issues.
Maybe you want to use ST_Intersects(A, B), which doesn't have the
robustness issue and is likely also faster.

--strk;

  ()   Free GIS & Flash consultant/developer
  /\  http://strk.keybit.net/services.html
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