[postgis-devel] [PostGIS] #780: Topology: adding a node over an edge could split the edge.

[PostGIS]

#780: Topology: adding a node over an edge could split the edge.
-----------------------+----------------------------------------------------
 Reporter:  aperi2007  |       Owner:  strk         
     Type:  defect     |      Status:  new          
 Priority:  medium     |   Milestone:  PostGIS 2.0.0
Component:  topology   |     Version:  trunk        
 Keywords:             |  
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Comment(by robe):

 Strk,

 Can a point ever cross a linestring.  I think as the definition goes --
 its only considered crossing if they share points but not all the points
 are fully contained in the other.  How can that ever be the case with a
 point and linestring.

 e.g.


 {{{
 SELECT ST_Crosses('LINESTRING(1 2, 3 4, 5 6)'::geometry, 'POINT(3
 4)'::geometry);
 SELECT ST_Crosses('POINT(3 4)'::geometry, 'LINESTRING(1 2, 3 4, 5
 6)'::geometry);
 }}}

 both return false.

 But this returns true:

 {{{

 SELECT ST_Crosses('MULTIPOINT(3 4, 9 9)'::geometry, 'LINESTRING(1 2, 3 4,
 5 6)'::geometry);
 }}}


 See manual description -- which Kevin had written up.  Though we should
 probably have an example of the point case.

 http://www.postgis.org/documentation/manual-svn/ST_Crosses.html

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/780#comment:2>
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