[postgis-tickets] [PostGIS] #4725: ST_MakeValid causes drastic loss of precision

[PostGIS]

#4725: ST_MakeValid causes drastic loss of precision
----------------------+--------------------------
  Reporter:  atlight  |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS GEOS
 Component:  postgis  |    Version:  3.0.x
Resolution:           |   Keywords:
----------------------+--------------------------
Changes (by pramsey):

 * milestone:  PostGIS 3.1.0 => PostGIS GEOS


Comment:

 As expected, this is a result of GEOS precision reduction routines in the
 old overlay engine trying to back off from repeated topology failures
 during overlay. And as hoped, the new overlay engine does not display the
 same behaviour. A valid output is generated, and the precision is
 basically the same.
 {{{
 postgis31=# select st_xmin(ST_MakeValid(geom)) FROM a;
       st_xmin
 -------------------
  144.9632208323141
 (1 row)

 postgis31=# select st_xmin(geom) FROM a;
       st_xmin
 -------------------
  144.9632208323141
 (1 row)
 }}}
 The solution will be to upgrade to GEOS 3.9 when it is released.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4725#comment:2>
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