[geos-devel] [GEOS] #620: Incorrect intersection between geometries
GEOS
geos-trac at osgeo.org
Wed Feb 6 03:34:02 PST 2013
#620: Incorrect intersection between geometries
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Reporter: rhf | Owner: geos-devel@…
Type: defect | Status: new
Priority: major | Milestone: 3.3.x
Component: Default | Version: 3.3.7
Severity: Unassigned | Keywords:
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I have two polylines A, B which partly overlap.
When computing the intersection C = intersection(A, B), geos reports the
correct result, which is a simple linestring with two points.
One of them is a noded intersection. The other one is not.
Hereafter I compute D = intersection(B, C). Of course D should equal C.
Instead I will only get a single point: the noded intersection.
This seems strange to me: either I would expect C also to be incorrect or
both queries to give the same result.
The same issue occurs when I try to compute B - C.
With similar cases involving a noded and none-noded intersection, I get
the correct results in all cases. For example when trying to reproduce the
issue with simple horizontal lines.
I have attached to small files in WKB format: A.txt, B.txt to be used as
input to reproduce the issue.
Actually the original polygons used as input where much larger, but I was
able to reduce their sizes such that they only have a few points. Also I
am working with geos via Spatialite, but I do not think this is relevant
for this issue.
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Ticket URL: <http://trac.osgeo.org/geos/ticket/620>
GEOS <http://geos.refractions.net/>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).
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