[postgis-tickets] [PostGIS] #2495: geography && large_bbox fails

[PostGIS]

#2495: geography && large_bbox fails
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 Reporter:  strk     |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 2.1.1
Component:  postgis  |     Version:  2.1.x        
 Keywords:           |  
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Comment(by pramsey):

 Geography bounding boxes are constructed in geocentric space (x/y/z) from
 objects inscribed on a unit sphere using spherical coordinates
 (theta/phi).  So, the north pole (0,90) in spherical coordinates is
 (0,0,1) in geocentric coordinates. This is one reason why geographic
 "bounding boxes" are hidden from end users: they'll never understand WTF
 is going on w/ them.

 Your "181 degrees wide" box is not 181 degrees wide, there's no such
 thing, in a world where ever arc is defined as the "shortest route between
 two points". It's 179 degrees wide, across the opposite side of the world
 you expect. The overlaps result is correct. Similarly, the "180 degrees
 wide" box is not actually 180 degrees wide, since the shortest great
 circle connecting 90,1 to -90,1 has to run over longitude 0 (check it
 out). A truly 180 degree line would be from 90,0 to -90,0.

 Trying to think about spherical geometry while looking at a mercator map
 is a recipe for a broken brain. Put a globe on your desk and get a piece
 of string.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2495#comment:7>
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