[postgis-tickets] [PostGIS] #3768: Geometry becomes invalid after a simple shift (black magic)

[PostGIS]

#3768: Geometry becomes invalid after a simple shift (black magic)
--------------------------+------------------------------
  Reporter:  tobiasreber  |      Owner:  pramsey
      Type:  defect       |     Status:  closed
  Priority:  medium       |  Milestone:  PostGIS 2.0.8
 Component:  postgis      |    Version:  2.1.x
Resolution:  wontfix      |   Keywords:  invalid Geometry
--------------------------+------------------------------

Comment (by dbaston):

 As far as the "very very very nearly invalid" piece, a good way to
 quantify this is `ST_MinimumClearance`.

 {{{
 SELECT ST_MinimumClearance('MULTIPOLYGON(((669054 215766.1, 669054.8
 215766.9, 669095.2 215807.2, 669064 215776.1, 669054 215766.1)))');
  st_minimumclearance
 ---------------------
   4.115903174892e-11
 }}}

 So your input can tolerate only 4e-11 distance units of perturbation
 before becoming invalid.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3768#comment:5>
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