[postgis-devel] [PostGIS] #1625: ST_Within and ST_DWithin disagree

PostGIS trac at osgeo.org
Tue Feb 28 09:31:28 PST 2012

#1625: ST_Within and ST_DWithin disagree
 Reporter:  strk     |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 2.0.0
Component:  postgis  |     Version:  trunk        
 Keywords:           |  

Comment(by nicklas):


 I would love to fix it, but as I wrote above I think it maybe is a bigger

 The quick fix (which I would hate) is to not project the point when
 calling ST_Dwithin or ST_Distance.

 The reason I wouldn't like that is because the consistence between the
 results of st_shortestline and st_closestpoint and st_distance and
 st_dwithin also has a value.

 But I see no other fix since the projected point cannot have better
 precision than it gets. So if st_shortestline really is to give the points
 from where st_distance uses (which was the idea when writing the function)
 this is what we get :-(

Ticket URL: <https://trac.osgeo.org/postgis/ticket/1625#comment:7>
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