Geometry Boost List: [ggl] incorrect result for an intersection

Subject: [ggl] incorrect result for an intersection
From: Vishnu (vrang3)
Date: 2011-04-15 14:46:03

I'm getting incorrect results from an intersection. A multi_polygon used as
the subject set is being intersected with a copy of itself. The output
should be the same as the input in this case. The input set has two
polygons:

POLYGON((447672 5.0335e+006,447890 5.0335e+006,447891 5.0335e+006,447872
5.03345e+006,447841 5.0334e+006,447804 5.03337e+006,447765
5.03335e+006,447755 5.03336e+006,447746 5.03338e+006,447739
5.03338e+006,447718 5.03338e+006,447696 5.03341e+006,447689
5.03344e+006,447672 5.0335e+006))POLYGON((447890 5.0335e+006,448000
5.0335e+006,448000 5.03308e+006,447956 5.03304e+006,447900 5.033e+006,447839
5.03296e+006,447835 5.03295e+006,447797 5.03299e+006,447784
5.03304e+006,447777 5.0331e+006,447766 5.03315e+006,447767
5.03316e+006,447778 5.03318e+006,447779 5.03324e+006,447816
5.03332e+006,447816 5.03333e+006,447780 5.03334e+006,447765
5.03335e+006,447804 5.03337e+006,447841 5.0334e+006,447872
5.03345e+006,447891 5.0335e+006,447890 5.0335e+006),(447849
5.03319e+006,447869 5.03319e+006,447907 5.03323e+006,447923
5.03326e+006,447951 5.0333e+006,447951 5.03332e+006,447929
5.03335e+006,447907 5.03336e+006,447900 5.03337e+006,447878
5.03338e+006,447872 5.03337e+006,447839 5.03331e+006,447813
5.03326e+006,447812 5.03323e+006,447829 5.0332e+006,447849 5.03319e+006))

and the output set has only one:

POLYGON((447872 5.03337e+006,447878 5.03338e+006,447900 5.03337e+006,447907
5.03336e+006,447929 5.03335e+006,447951 5.03332e+006,447951
5.0333e+006,447923 5.03326e+006,447907 5.03323e+006,447869
5.03319e+006,447849 5.03319e+006,447829 5.0332e+006,447812
5.03323e+006,447813 5.03326e+006,447839 5.03331e+006,447872 5.03337e+006))

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