[geos-devel] [GEOS] #712: Single-sided buffer gives unexpected result

GEOS geos-trac at osgeo.org
Tue Dec 2 06:00:34 PST 2014

#712: Single-sided buffer gives unexpected result
 Reporter:  pmeems      |       Owner:  geos-devel@…              
     Type:  defect      |      Status:  new                       
 Priority:  minor       |   Milestone:  3.4.3                     
Component:  Default     |     Version:  3.4.2                     
 Severity:  Unassigned  |    Keywords:                            
 I have this linestring:
 LINESTRING(6.59607872405104612 53.00390260763848715, 6.5970405434596513
 53.00362892273712845, 6.59798287063396227 53.00336078433459619,
 6.59864650169724065 53.00303357725661613, 6.59938686388177764
 53.00283982209050748, 6.60119220843164101 53.00211012469529948,
 6.60112679624460608 53.00208460961093948, 6.60026057476097616
 53.00174672587350244, 6.58878962886061181 52.99727229739764311)

 I create a single-sided buffer of -9E-10 (-70m) with flat endcaps and
 round joinstyle.
 This should create a polygon left of the line.
 But it creates a buffer as in the attached image. You can see that in the
 right corner the polygon is also at the right of the line. This happens
 only at sharp corners.

 I've mentioned this on the mailing list already.
 I tried searching for an existing ticket but couldn't find it.
 I don't know if this is also a problem with JTS, probably it is.

Ticket URL: <http://trac.osgeo.org/geos/ticket/712>
GEOS <http://geos.refractions.net/>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).

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