[postgis-tickets] [PostGIS] #2739: ST_Intersection problem

[PostGIS]

#2739: ST_Intersection problem
---------------------+------------------------------------------------------
 Reporter:  pascal   |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 2.1.4
Component:  postgis  |     Version:  2.1.x        
 Keywords:           |  
---------------------+------------------------------------------------------

Comment(by robe):

 Not following you.  What do you think is wrong here:

 I'm running this query:


 {{{
 SELECT b.id_0 As b, a.id_0 as a, ST_AsText(ST_Intersection(a.geom,b.geom))
 AS intersection_geom FROM verschn_fehler.object AS a,
 verschn_fehler.parcels AS b WHERE a.geom && b.geom;

 --and get 4 rows back

  b | a  |

                                 intersection_geom


 ---+----+-------------------------------------------------------------------------------------------
 ----------------------------------------------------------------------------------------------------
 ----------------------------------------------------------------------------------------------------
 ----------------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------
  1 | 10 | GEOMETRYCOLLECTION(LINESTRING(651917.046727391
 165883.257018676,651918.909381221 165875.80
 6403356),LINESTRING(651918.909381221 165875.806403356,651925.425926848
 165849.740220846),POLYGON((65
 2026.642685167 166349.064004929,652076.446967838
 166193.859961257,651956.345108947 166087.723434796,
 651978.689640834 165892.208780788,651917.046727391
 165883.257018676,651853.038048234 166139.29173530
 2,652026.642685167 166349.064004929)))
  2 | 10 | GEOMETRYCOLLECTION EMPTY
  4 | 10 | MULTIPOLYGON(((651629.556330106 166612.81993413,651764.552769598
 166594.358882576,651853.0
 38048234 166139.291735302,651718.934457652
 166490.972408686,651629.556330106 166612.81993413)),((651
 917.046727391 165883.257018676,651918.909381221
 165875.806403356,651925.425926848 165849.740220846,6
 51869.760047887 165848.916250258,651851.255982418
 165952.608843544,651898.337289386 165958.094770693
 ,651853.038048234 166139.291735302,651917.046727391 165883.257018676)))
  5 | 10 | POLYGON((651764.552769598 166594.358882576,651956.345108947
 166568.130870357,652026.642685
 167 166349.064004929,651853.038048234 166139.291735302,651764.552769598
 166594.358882576))
 (4 rows)
 }}}


 If I run the more proper:


 {{{
 SELECT b.id_0 As b, a.id_0 as a, ST_AsText(ST_Intersection(a.geom,b.geom))
 AS intersection_geom FROM verschn_fehler.object AS a,
 verschn_fehler.parcels AS b WHERE ST_Intersects(a.geom,b.geom);
 }}}


 I get 3 rows back (minus the empty geometry colloection)

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/2739#comment:3>
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