[postgis-devel] [PostGIS] #573: ST_Contains(geog, geog) gives wrong answer

[PostGIS]

#573: ST_Contains(geog, geog) gives wrong answer
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 Reporter:  pramsey  |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 1.5.2
Component:  postgis  |     Version:  1.5.X        
 Keywords:           |  
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 {{{
 create table gpoints (id integer, g geography);
 insert into gpoints values
   (1, 'POINT(-120.585938 55.195313)'),
   (2, 'POINT(116.367188 57.656250)');
 select
   st_astext(g),
   st_covers('POLYGON((-128.3203125 61.171875, -103.7109375 -54.140625,
 72.0703125 0.3515625, 134.296875 15.8203125, 17.2265625 71.3671875,
 -6.328125 75.5859375, -128.3203125 61.171875))'::geography,g)
 from gpoints;
 select
   st_astext(g),
   st_covers('POLYGON((-124.453125 64.6875, -127.6171875 -46.0546875,
 51.6796875 -18.6328125, 46.0546875 -9.84375, 47.8125 17.2265625,
 50.9765625 32.34375,-124.453125 64.6875))'::geography,g)
 from gpoints;
 }}}
 This appears to be similar to #562, where the point-in-polygon routine was
 failing because the generated "point outside" the polygon actually wasn't
 outside. In the second example, and outside point simply cannot be
 generated and everything stops.

 I fear that as polygons get bigger, the question of what they "bound"
 comes into sharp relief in a way that is less problematic for small
 polygons. While most geodata is small enough to be obviously containing
 the "smaller" part of the sphere, it's trivially easy to generate a large
 polygon using a global mercator map in a GUI. Click, click, click, and you
 have a query polygon that visually covers most of the globe.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/573>
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