[geos-devel] [GEOS] #959: Reversed result in GEOSClipByRect

GEOS geos-trac at osgeo.org
Mon Mar 11 10:25:03 PDT 2019

#959: Reversed result in GEOSClipByRect
 Reporter:  Algunenano   |       Owner:  geos-devel@…
     Type:  defect       |      Status:  new
 Priority:  major        |   Milestone:  3.5.2
Component:  Default      |     Version:  3.5.0
 Severity:  Significant  |  Resolution:
 Keywords:               |

Comment (by mdavis):

 Given that this geometry is only slightly invalid (a single collapsed line
 segment), and given the relatively simplicity of clipping to a rectangle,
 it seems like it might be technically feasible to make clipping more
 tolerant of some invalid inputs.  This might require an entirely new
 algorithm, though.

 The other option for now is to ensure the input geometry is valid.  In
 this case that can be done via a simple linear scan of the polygon ring,
 to detect and remove the collapsed segment.  Perhaps that can be provided
 as a utility function. Or perhaps MakeValid could be enhanced with hints
 to optimize what kinds of cleaning approaches are used.

Ticket URL: <https://trac.osgeo.org/geos/ticket/959#comment:3>
GEOS <http://trac.osgeo.org/geos>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).

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