[postgis-users] error with overlay and disjoint

[Emilia Venturato]

Thank you strk.
The geoms were not valid, as you wrote.
I can't find the original shapefile, unfortunally. I tried but without 
results.
I run geomunion last year, with an old version of postgis.


Thank you again.
Lia

Alle 12:22, mercoledì 19 ottobre 2005, strk at refractions.net ha probabilmente 
scritto:
> Emilia, these error are usually due to invalid geometries:
>
> 	# select gid,isvalid(the_geom) from poligoni_geomunion;
> 	NOTICE:  Self-intersection
> 	NOTICE:  Self-intersection
> 	 gid | isvalid
> 	-----+---------
> 	 217 | f
> 	 219 | f
> 	(2 rows)
>
> Have the geoms been produced by a call to geomunion (as the
> name suggests) ? In this case it would help finding out the
> original geometries as the bug is there.
>
> --strk;
>
> On Wed, Oct 19, 2005 at 08:15:04AM +0200, Emilia Venturato wrote:
> > Hi all.
> > Concerning my previous mail, I found the problem: it did not lay in the
> > number of records.
> > Two the_geom have been made with GeomUnion function from adjoining
> > shapes; the resulting shapes are multipolygon with internal divisions,
> > and overlay gives an error with this kind of shapes.
> > Unfortunately, I did not find a command which removes the internal
> > divisions (of course a workaround is to export it and edit it, but I
> > would like to find a cleaner solution).
> > All the best.
> >
> > Alle 16:05, lunedì 17 ottobre 2005, Emilia Venturato ha probabilmente 
scritto:
> > > Hi all,
> > >
> > > I'm trying to extract from a postgis table (the_geom of table1: 25.000
> > > records) all the id of that records wich overlay (also partially) with
> > > a study_area (the_geom of table2).
> > > I try:
> > >
> > > select a.id, disjoint (a.the_geom, b.the_geom) from table1 a, table2 b
> > > where disjoint (a.the_geom, b.the_geom) is false;
> > > select a.id, overlay (a.the_geom, b.the_geom) from table1 a, table2 b
> > > where overlay (a.the_geom, b.the_geom) is true;
> > >
> > > In both queries, I had an error:
> > > ERROR:  GEOS disjoin() threw an error!
> > > ERROR:  GEOS overlay() threw an error!
> > >
> > > I tryed with a subsample (900 records) and the select worked.
> > > Have you same suggestion? Could it be a problem in the (too large?)
> > > number of records?
> > > Thank you in advance.
> > > Lia
> >
> > --
> > (Emi)Lia Venturato
> > venturato at faunalia.it    venturato at jabber.org    www.faunalia.it
> > Piazza Garibaldi 4 56025 Pontedera (PI)  Italy
> > Tel: (+39) 347-2770007 Fax (+39) 0587-213742
> > Linux User: 388585 http://counter.li.org
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>
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-- 
(Emi)Lia Venturato
venturato at faunalia.it    venturato at jabber.org    www.faunalia.it
Piazza Garibaldi 4 56025 Pontedera (PI)  Italy
Tel: (+39) 347-2770007 Fax (+39) 0587-213742
Linux User: 388585 http://counter.li.org