[postgis-devel] Difference bug (was: Postgis)

[strk at refractions.net]

The following query fails with both GEOS and JTS (CVS):

 select
 difference(
 '01030000000100000009000000215DE2E756673A419CB1D50C8868524179A3C8DF59673A410B9EDB5D876852419D13A3314B673A4173AB24F282685241239C6DD83A673A41ECC950DC80685241CC46FE2A2F673A414B3B231C80685241E74CB0C52D673A41EFB7A7E0806852417B14AE473B673A416766661683685241D7A370BD53673A4185EB518887685241215DE2E756673A419CB1D50C88685241',
 '01030000000100000005000000B87B621331673A4136EA036B81685241B90E118236673A41D91150717F6852415F2CA05B2E673A41A160D97B7E685241C3F528DC29673A41CDCCCC3C80685241B87B621331673A4136EA036B81685241'
 );

Intersection outside segment envelopes: (1730391.4018133604, 4825630.753482913, NaN)
NOTICE:  Directed Edge visited twice during ring-building at (1730355.8460224771, 4825601.642585231, NaN)
ERROR:  JTS difference() threw an error!

The input geometries are found both valid and simple.
Any precision reduction fixed the problem.

Martin, is it a robustness issue ?

--strk;

On Mon, Jul 25, 2005 at 10:48:50AM +0200, strk at refractions.net wrote:
> Ciao Tommaso,
> I did read your report, but could not find the time to
> take care of it yet.
> 
> Filing a bug report in the tracker is a good idea, but
> posting also on postgis-devel gives your problem a broader
> audience.
> 
> --strk;
> 
> On Mon, Jul 25, 2005 at 10:44:02AM +0200, Tommaso Nolli wrote:
> > Hi,
> > I've submitted a bug on http://postgis.refractions.net/bugs; I see that 
> > the bug is assigned to you, but it seems that this bug system is not 
> > very used..., so is this the right place to submit bugs/problems? And 
> > what is the state of my submission?
> > 
> > Thanks in advance,
> > Tommaso Nolli
> > 
> > P.S.: this is the text of my bug submission:
> > Issuing a select difference(geom, geom) will raise an error
> > 
> > ERROR: GEOS difference() threw an error!
> > 
> > I have a dump and a sample sql in order to reproduce the error, where 
> > can I submit this files?
> > By now I have posted this zip file at this URL: 
> > http://siti.abacogroup.com/support/pg/PostGisError.zip
> > 
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