#323: A point interpolated from a line does not always intersect the same line
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Reporter: starsareblue | Owner: geos-devel at lists.osgeo.org
Type: defect | Status: reopened
Priority: major | Milestone:
Component: Default | Version: 3.2.0
Severity: Unassigned | Resolution:
Keywords: |
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Changes (by starsareblue):
* status: closed => reopened
* resolution: invalid =>
Comment:
That is true, but in the following case, the projection point (0, -1) is
exactly representable. Is it perhaps an issue with the MultiLineString?
I would expect the intersection of the following MultiLineString with
the Point to produce either (0, -1) or (1, 0) but instead it produces
(-1, 1). The distance() function works correctly though. So
interpolation/projection onto a MultiLineString must be done manually
for now for each individual LineString.
{{{
import shapely.geometry as g
point = g.Point(1, 0)
l1 = g.LineString([(0, 2), (0,0)])
l2 = g.LineString([(-1, 1), (1, 1)])
m = g.MultiLineString([l1.coords, l2.coords])
assert m.interpolate(m.project(point)).coords[0] == (-1, 1) # True, but
wrong
assert m.interpolate(m.project(point)).coords[0] == (0, -1) # Fails
assert m.interpolate(m.project(point)).coords[0] == (1, 0) # Fails
}}}
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Ticket URL: <http://trac.osgeo.org/geos/ticket/323#comment:2>
GEOS <http://geos.refractions.net/>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).