[postgis-tickets] [PostGIS] #4558: ST_Intersects returns FALSE while ST_Intersection returns a geometry.

[PostGIS]

#4558: ST_Intersects returns FALSE while ST_Intersection returns a geometry.
----------------------+---------------------------
  Reporter:  olehz    |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 2.5.4
 Component:  postgis  |    Version:  2.5.x
Resolution:           |   Keywords:
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Comment (by mdavis):

 This is a classic case caused by numeric precision issues.  The JTS FAQ
 has an [explanation](https://locationtech.github.io/jts/jts-faq.html#D8)
 of why this happens.  JTS produces the same result.

 This case is particularly interesting/egregious, because it can be reduced
 to the following:
 ```
 A: LINESTRING (-57 6.939016666666666, -57.001016666666665
 7.935202777777778)
 B: LINESTRING (-57.2696825964778 7.15879416404005, -57 6.93901666666667)
 ```
 By inspection these two lines do intersect.  So the line segment
 intersection computation is computing an incorrect answer.  Much work has
 been done to try and make this computation robust, but clearly there is
 more work to do.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4558#comment:2>
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