[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
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 Reporter:  dmiranda                                       |       Owner:  pramsey      
     Type:  defect                                         |      Status:  new          
 Priority:  medium                                         |   Milestone:  PostGIS 2.0.0
Component:  postgis                                        |     Version:  trunk        
 Keywords:  st_union topologyexception noded intersection  |  
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Comment(by jgrocha):

 The same dataset, imported in PostGIS 1.5 runs fine.

 PostGIS version used:
 "1.5 USE_GEOS=1 USE_PROJ=1 USE_STATS=1"

 Commands used:
 psql geotuga < st_union_topology_exception.sql

 select gid from st_union_topology_exception where not st_isvalid(geom);
 No invalid geometries were found

 psql geotuga -c "select st_astext(st_envelope(st_union(geom))) from
 st_union_topology_exception;"
 POLYGON((-55.3756654961996 -28.9576596206607,-55.3756654961996
 -27.1734940596501,-53.0671265720575 -27.1734940596501,-53.0671265720575
 -28.9576596206607,-55.3756654961996 -28.9576596206607))

 select st_extent(geom) from st_union_topology_exception;
 "BOX(-55.3756654961996 -28.9576596206607,-53.0671265720575
 -27.1734940596501)"

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/1198#comment:2>
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