[geos-devel] [GEOS] #741: GEOSSimplify() returns empty polygon if inner ring dimension < simplify distance

[GEOS]

#741: GEOSSimplify() returns empty polygon if inner ring dimension < simplify
distance
------------------------+--------------------------
 Reporter:  rouault     |      Owner:  geos-devel@…
     Type:  defect      |     Status:  new
 Priority:  major       |  Milestone:  3.4.3
Component:  Default     |    Version:  svn-trunk
 Severity:  Unassigned  |   Keywords:
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 Demonstrated with OGR scripting, but the issue is in GEOS

 {{{
 from osgeo import ogr
 ogr_geom = ogr.CreateGeometryFromWkt('POLYGON ((-180 90,180 90,180 -90,180
 -90,-180 -90,-180 90),(0 0,0 0.0001,0.0001 0.0001,0 0))')
 simple_geom = ogr_geom.Simplify(0.005)
 print simple_geom # prints POLYGON EMPTY --> unexpected

 ogr_geom = ogr.CreateGeometryFromWkt('POLYGON ((-180 90,180 90,180 -90,180
 -90,-180 -90,-180 90),(0 0,0 0.0001,0.0001 0.0001,0 0))')
 simple_geom = ogr_geom.Simplify(0.00005) # prints POLYGON ((-180 90,180
 90,180 -90,-180 -90,-180 90),(0 0,0.0001 0.0001,0.0 0.0001,0 0)) --> OK
 }}}

 The above is an artificial example reproducing a real world situation

 It seems to be an issue failed simplification of the inner ring.

 Reproduced with latest GEOS trunk r4082

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Ticket URL: <https://trac.osgeo.org/geos/ticket/741>
GEOS <http://trac.osgeo.org/geos>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).