[postgis-tickets] [PostGIS] #4568: Oversimplification of polygon inner rings in ST_Simplify

[PostGIS]

#4568: Oversimplification of polygon inner rings in ST_Simplify
------------------------+---------------------------
 Reporter:  Algunenano  |      Owner:  pramsey
     Type:  defect      |     Status:  new
 Priority:  high        |  Milestone:  PostGIS 3.0.1
Component:  postgis     |    Version:  3.0.x
 Keywords:              |
------------------------+---------------------------
 Initially reported by Komzpa

 I went to far when dropping inner rings of polygons in my optimization of
 inner rings, you can only drop all inner rings when the outer ring
 collapse, not when any of them collapse.

 Bug example:
 {{{
 Select ST_AsText(ST_Simplify('POLYGON((0 0, 100 0, 100 100, 0 100, 0 0),
 (20 20, 20 40, 40 40, 40 20, 20 20), (1 1, 1 5, 5 5, 5 1, 1
 1))'::geometry, 10));
                                st_astext
 ------------------------------------------------------------------------
  POLYGON((0 0,100 0,100 100,0 100,0 0),(20 20,20 40,40 40,40 20,20 20))
 }}}

 Same polygon but with the smaller inner ring first:
 {{{
 Select ST_AsText(ST_Simplify('POLYGON((0 0, 100 0, 100 100, 0 100, 0 0),
 (1 1, 1 5, 5 5, 5 1, 1 1), (20 20, 20 40, 40 40, 40 20, 20
 20))'::geometry, 10));
                st_astext
 ----------------------------------------
  POLYGON((0 0,100 0,100 100,0 100,0 0))
 (1 row)
 }}}

 PR: https://github.com/postgis/postgis/pull/504
 Affected 3.0 and master

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4568>
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