[postgis-devel] [PostGIS] #1198: ST_Union fails on some sets of polygons. Snapping works around the problem

[PostGIS]

#1198: ST_Union fails on some sets of polygons. Snapping works around the problem
-----------------------+----------------------------------------------------
  Reporter:  dmiranda  |       Owner:  pramsey                                      
      Type:  defect    |      Status:  closed                                       
  Priority:  medium    |   Milestone:  PostGIS 2.0.0                                
 Component:  postgis   |     Version:  trunk                                        
Resolution:  wontfix   |    Keywords:  st_union topologyexception noded intersection
-----------------------+----------------------------------------------------

Comment(by pracine):

 Was this fixed?

 I must say I experience this quite often with normal datasets with both
 ST_Union and ST_Difference with the latest tarball:

 "POSTGIS="2.0.0beta5SVN" GEOS="3.3.2-CAPI-1.7.2" PROJ="Rel. 4.6.1, 21
 August 2008" GDAL="GDAL 1.9.0, released 2011/12/29" LIBXML="2.7.8" (core
 procs from "2.0.0beta5SVN" need upgrade) RASTER (raster procs from
 "2.0.0beta5SVN" need upgrade)"

 For ST_Union I can make it to work if I ST_SnapToGrid(geom, 0.000001).
 Below than 0.000001, it fails.

 I can provide data if necessary.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1198#comment:5>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.