[PostGIS] #5699: ERROR: XX000: SQL/MM Spatial exception - geometry crosses an edge

[PostGIS]

#5699: ERROR:  XX000: SQL/MM Spatial exception - geometry crosses an edge
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  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  defect             |     Status:  assigned
  Priority:  medium             |  Milestone:  PostGIS 3.4.3
 Component:  topology           |    Version:  3.4.x
Resolution:                     |   Keywords:  robustness
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Comment (by Lars Aksel Opsahl):

 Replying to [comment:7 strk]:
 > Raising an exception instead of silently creating an invalid topology is
 done in this PR: https://git.osgeo.org/gitea/postgis/postgis/pulls/195
 >
 > With the code in that PR we now get, upon adding the final line:
 > {{{
 > ERROR:  Spatial exception - geometry boundary touches interior of edge 1
 > }}}
 >
 > This is still puzzling because the boundary of the geometry is supposed
 to be the same as the new node being created upon splitting edge 2, so if
 that boundary touches interior of edge 1 then also the added point should,
 but was found to be at a squared distance of `1.64235648202829e-31` units.
 >
 > I suspect GEOS is internally reducing the precision of the geometries
 upon catching a topology error due to the same robustness troubles we are
 having.

 When the overlay NG code was added in JTS was not one intentions make
 spatial operations more robust and avoid Topology exceptions and I assume
 that may involve some kind off snapping ?
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5699#comment:10>
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