[postgis-devel] [PostGIS] #845: ST_Intersects() precision error - returns false instead of true

PostGIS trac at osgeo.org
Thu Feb 24 06:02:18 PST 2011


#845: ST_Intersects() precision error - returns false instead of true
------------------------+---------------------------------------------------
 Reporter:  cdestigter  |       Owner:  pramsey      
     Type:  defect      |      Status:  new          
 Priority:  medium      |   Milestone:  PostGIS 2.0.0
Component:  postgis     |     Version:  1.5.X        
 Keywords:              |  
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Comment(by nicklas):

 Yes, and also changing "outside polygon" from -1 to 0, but I think that
 will be more rewriting in within, intersects and som on than doing the
 changes in distance. But it looks like the algoritm in counting windings
 actually returns 0 for outside polygon and then it is chenged:


 {{{
 01168         if (wn == 0)
 01169                 return -1;
 01170         return 1;
 }}}


 But, don't you think from what yo said earlier that it maybe is better to
 just send all of it to GEOS?
 At least until maybe we get some sort of indexing of vertex-points in
 PostGIS like Paul has sketched. If that things gets implemented I guess at
 east ST_Intersects maybe can be a very fast native PostGIS function. Maybe
 also contains and Within, I don't know.

 Is there some link describing the prepared geometries? How, are they
 cached?


 /Nicklas

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/845#comment:23>
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