#531: UnaryUnion of an line collapsed to a point returns EMPTY
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Reporter: strk | Owner: geos-devel@…
Type: defect | Status: closed
Priority: major | Milestone: 3.8.0
Component: Default | Version: 3.3.3
Severity: Unassigned | Resolution: wontfix
Keywords: |
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Comment (by mdavis):
Yes, perhaps it is inconsistent. Tricky to know what the right semantic
should be.
The fact that collapsed LineStrings are actually invalid muddies the water
even more, since returning a single-point LineString would violate the
principle of always returning a valid geometry. This is actually one
difference to the JTS 476 issue, since in that case the inputs are valid.
Although the invalidity of single-point LineStrings has always struck me
as overly-limiting.
There's an appeal to returning *something* non-empty, to indicate that
there are actual vertices in the input, which should not just disappear.
So then should a POINT be returned, or hold our nose and return a single-
point LINESTRING?
I'm not sure there is a single answer which address all requirements.
Providing a strict mode in addition to full mode might satisfy more
people. But that's a lot more complexity.
--
Ticket URL: <https://trac.osgeo.org/geos/ticket/531#comment:8>
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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