[postgis-devel] [PostGIS] #1170: North Pole Intersection fails with "Coordinate values out of range"

[PostGIS]

#1170: North Pole Intersection fails with "Coordinate values out of range"
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 Reporter:  jgilman   |       Owner:  pramsey      
     Type:  defect    |      Status:  new          
 Priority:  critical  |   Milestone:  PostGIS 1.5.4
Component:  postgis   |     Version:  1.5.X        
 Keywords:            |  
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Comment(by chodgson):

 The following query shows that it is possible to represent the pole
 correctly as a geography.

 select st_astext(ST_GeogFromText( 'POINT(0 90)'));

 However, the actual intersection calculation is done in a projected,
 planar coordinate system, and then converted back to spherical coordinates
 - I suspect that something goes amiss in the conversion, and the result is
 possibly 90.00000000000001 or something like that.

 The current implementation of intersection for geographies is only an
 approximation using this technique of re-projecting to a "good enough"
 local planar projection and doing the intersection calculation in the land
 of planes before projecting back.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1170#comment:2>
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