[postgis-devel] ST_Intersection failing on valid geometries

[Ralf Suhr]

Hi Komяpa,

you have some unwanted geometries inside your multipolygons. Remove this and 
test it again.

select ST_Area((ST_Dump(geom)).geom) from bad_intersections;
 shows some "sliver polygons" with area 0


Gr
Ralf

Am Freitag 27 Juni 2014, 14:48:09 schrieb Komяpa:
> Hi,
> 
> 2014-06-27 14:21 GMT+03:00 Rémi Cura <remi.cura at gmail.com>:
> > Seems like a precision issue.
> > Can you try to translate your  geometry and round theim (ST_SnpaToGrid) a
> > bit to reduce the number of digits?
> 
> I'd prefer not to, as
> a) this is intermediate step in more complex processing;
> b) I bumped into this issue multiple times, and now I have a testing
> case dataset.
> 
> Can something be done inside PostGIS not to fail on such geometries?
> 
> > Cheers,
> > Rémi-C
> > 
> > 2014-06-27 12:18 GMT+02:00 Komяpa <me at komzpa.net>:
> >> Hi,
> >> 
> >> I managed to create a set of geometries that I'd like to intersect.
> >> 
> >> POSTGIS="2.1.3 r12547" GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0,
> >> 6 March 2012" GDAL="GDAL 1.11.0, released 2014/04/16" LIBXML="2.9.1"
> >> LIBJSON="UNKNOWN" (core procs from "2.1.2 r12389" need upgrade)
> >> TOPOLOGY (topology procs from "2.1.2 r12389" need upgrade) RASTER
> >> (raster procs from "2.1.2 r12389" need upgrade)
> >> 
> >> Test table:
> >> http://pastebin.com/qSYLGfvs
> >> 
> >> After that:
> >> 
> >> select ST_Intersection(p.geom, g.geom) from bad_intersections p,
> >> bad_intersections g;
> >> 
> >> ERROR:  XX000: Error performing intersection: TopologyException: found
> >> non-noded intersection between LINESTRING (1.45784e+07 -1.40333e+06,
> >> 1.45784e+07 -1.40333e+06) and LINESTRING (1.45784e+07 -1.40333e+06,
> >> 1.45784e+07 -1.40333e+06) at 14578380.693885569 -1403332.55464
> >> LOCATION:  pg_error, lwgeom_pg.c:162
> >> Time: 10,674 ms
> >> 
> >> All geometries are valid.
> >> 
> >> Can this be fixed?
> >> 
> >> --
> >> Darafei "Komяpa" Praliaskouski
> >> OSM BY Team - http://openstreetmap.by/
> >> xmpp:me at komzpa.net mailto:me at komzpa.net
> >> _______________________________________________
> >> postgis-devel mailing list
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> >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-devel
> > 
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