[PostGIS] #6095: add fixVertexSegmentPairsBelowDistance

[PostGIS]

#6095: add fixVertexSegmentPairsBelowDistance
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  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  enhancement        |     Status:  new
  Priority:  medium             |  Milestone:  PostGIS Fund Me
 Component:  topology           |    Version:
Resolution:                     |   Keywords:
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Comment (by Lars Aksel Opsahl):

 Comment @strk


 {{{
 strk (osgeo)
 the question would then be: fix how ?
 I can think of 2 possible fixes: (1) drop the vertex (2) snap the segment
 to the vertex (3) add a node where the vertex is and hope for the bext
 *best
 (3) is effectively going to do (2)
 so it's really 2 possible fixes
 oh, and I'm aware of a bug I'm not sure I filed as a trac ticket, that if
 imore than 1 segment of the SAME EDGE are closer than tolerance from a
 node, only one will snap
 that one would be nice to fix actually
 can't find a trac ticket so I probbaly haven't filed it, but I'm pretty
 sure I saw it happen with one of your recently filed robustness testcases
 or by effect of my writing a simplified test for one of those
 I remember I pretended not to see th eproblem because I was focusing on
 fixing your specific case, but the test should be easy: (1) add a single
 edge with 2 segments being almost collinear (2) add a node near between
 the two segments, near the common vertex
 in an ideal world we should end up with no Vertex-Segment pair beow
 distance, but as of today, only one segment will snap to the incoming n

 }}}
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Ticket URL: <https://trac.osgeo.org/postgis/ticket/6095#comment:5>
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