[postgis-tickets] [PostGIS] #3464: ERROR: lwt_ChangeEdgeGeom could not construct face X, on the left of edge Y

[PostGIS]

#3464: ERROR: lwt_ChangeEdgeGeom could not construct face X, on the left of edge Y
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  Reporter:  strk      |      Owner:  strk
      Type:  defect    |     Status:  new
  Priority:  medium    |  Milestone:  PostGIS Future
 Component:  topology  |    Version:  trunk
Resolution:            |   Keywords:  robustness
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Comment (by strk):

 To summarize this issue, the problem derives from being unable to node
 that crosses a couple of edges which are almost parallel. The noding
 procedure (based on ST_Difference) gives us a correctly noded output BUT
 the correctly noded output makes the initial part of the two edges
 collapse on each other. When adding the new node to the topology
 (AddPoint) we make no effort to handle the edge-collapsing.

 What the algorithm does right now, on adding a new point, is just snapping
 the closest edge to the new node, rather than snapping _all_ edges below
 threshold and handling the collapses.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3464#comment:15>
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