[geos-devel] [GEOS] #910: Difference operation resulted with a wrong geometry as a result of a precision incorrections

GEOS geos-trac at osgeo.org
Sun Aug 12 23:00:20 PDT 2018


#910: Difference operation resulted with a wrong geometry as a result of a
precision incorrections
-------------------------+-------------------------------------------------
 Reporter:  yanivnavon   |      Owner:  geos-devel@…
     Type:  defect       |     Status:  new
 Priority:  major        |  Milestone:
Component:  Default      |    Version:  3.6.2
 Severity:  Significant  |   Keywords:  polygon, geometry, geometries,
                         |  difference, union, multipolygon
-------------------------+-------------------------------------------------
 Difference between two geometries results with a wrong geometry as
 sometimes systems can hold up to 6 digits after the decimal point, hence
 cannot hold the full number. In such cases, GEOS calculator might take two
 points as "does not match" each other. Originally, these points are
 matching each other.

 Screenshot:
 http://dev.skylinesoft.com/Up/Navon/General/screenshot.png

 ** With reference to bug #704:

 1) Geometry A:
 POLYGON ((580 337, 580 342.1, 581.3 338.8, 581.3666666666667
 338.8833333333333, 581.4166666666666 339, 581.45 339.1166666666667,
 581.5166666666667 339.26666666666665, 582.4 341.9, 583.5 337.1, 580 337))
 2) Geometry B:
 POLYGON ((578.3 340.9, 578.4166666666666 340.9166666666667, 578.55
 340.9166666666667, 585.1 341, 585 340.4, 578.9 340.4, 578.3 340.9))

 3) Union A -> B = C (Multipolygon)
 4) Difference C -> B

-- 
Ticket URL: <https://trac.osgeo.org/geos/ticket/910>
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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