[Boost-bugs] [Boost C++ Libraries] #10803: union algorithm returning invalid geometry

Subject: [Boost-bugs] [Boost C++ Libraries] #10803: union algorithm returning invalid geometry
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-11-19 12:26:13

#10803: union algorithm returning invalid geometry
-------------------------------------------+---------------------------
 Reporter:  Volker Schöch <vschoech@…>     |      Owner:  barendgehrels
     Type:  Bugs                           |     Status:  new
Milestone:  To Be Determined               |  Component:  geometry
  Version:  Boost 1.57.0                   |   Severity:  Regression
 Keywords:  union, multi-polygon, polygon  |
-------------------------------------------+---------------------------
 My "_intPolygon" type is actually a multi-polygon, using a polygon type
 that is based on '''int''', oriented '''counter-clockwise''' and
 '''open''' (not closed). Please consider the following example:
 {{{
 _intPolygon polygonA;
 boost::geometry::read_wkt("MULTIPOLYGON(((3174 1374,3174 2886,1374
 2886,1374 2139,3174 1374)))", polygonA); // does not throw
 boost::geometry::correct(polygonA); // remove redundant closing point
 returned by wkt
 boost::geometry::is_valid(polygonA); // returns true

 _intPolygon polygonB;
 boost::geometry::read_wkt("MULTIPOLYGON(((1374 1092,1734 1092,3174
 2526,3174 2886,1374 2886,1374 1092)))", polygonB); // does not throw
 boost::geometry::correct(polygonB); // remove redundant closing point
 returned by wkt
 boost::geometry::is_valid(polygonB); // returns true

 _intPolygon polygonC;
 boost::geometry::union_(polygonA, polygonB, polygonC);
 // polygonC = MULTIPOLYGON(((1374 809,1374 1092,1734 1092,3529 1718,3174
 1374,3174 2526,3174 2886,1374 2886,1374 2139,1374 809)))
 boost::geometry::is_valid(polygonC); // returns FALSE

 boost::geometry::remove_spikes(polygonC);
 // polygonC = MULTIPOLYGON(((1374 1092,1734 1092,3529 1718,3174 1374,3174
 2526,3174 2886,1374 2886,1374 2139,1374 1092)))
 boost::geometry::is_valid(polygonC); // still returns FALSE
 }}}

 May be related to #10661.[[BR]]
 May be related to #9828.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/10803>
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