[postgis-devel] [PostGIS] #1976: ST_Intersects() returns false while ST_Intersection returns a geography

[PostGIS]

#1976: ST_Intersects() returns false while ST_Intersection returns a geography
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  Reporter:  mhiper3pg  |       Owner:  pramsey      
      Type:  defect     |      Status:  closed       
  Priority:  medium     |   Milestone:  PostGIS 1.5.6
 Component:  postgis    |     Version:  1.5.X        
Resolution:  invalid    |    Keywords:               
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Changes (by pramsey):

  * status:  new => closed
  * resolution:  => invalid


Comment:

 There are many things going on here.

 First, probably ST_Intersects is actually *right*, the polygon does
 intersect Iowa, see http://blog.opengeo.org/2012/04/30/the-earth-is-not-
 flat-volume-2/ for an explanation.

 Second, because ST_Intersection is not actually running in spherical
 coordinates (it's a cheater wrap to a planar projection) the results are
 not consistent with ST_Intersects, which *is* running in spherical.

 In all, I think I need to either make the planar hack more sophisticated
 (rathole) or start thinking about how to do constructive geometry on the
 sphere (ratmine).

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1976#comment:1>
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