[Boost-bugs] [Boost C++ Libraries] #13510: Boost::intersection giving wrong results when intersection is calculated between 2 polygons in Boost-1.61, where as Boost-1.55 is giving correct results.

Subject: [Boost-bugs] [Boost C++ Libraries] #13510: Boost::intersection giving wrong results when intersection is calculated between 2 polygons in Boost-1.61, where as Boost-1.55 is giving correct results.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2018-04-04 09:11:40

#13510: Boost::intersection giving wrong results when intersection is calculated
between 2 polygons in Boost-1.61, where as Boost-1.55 is giving correct
results.
------------------------------+----------------------------
 Reporter:  sumanth.kaliki@…  |      Owner:  Barend Gehrels
     Type:  Bugs              |     Status:  new
Milestone:  Boost 1.61.0      |  Component:  geometry
  Version:  Boost 1.61.0      |   Severity:  Regression
 Keywords:                    |
------------------------------+----------------------------
 Hi,

 When calculating intersections between 2 polygons, the
 boost::geometry::intersection is giving wrong results in Boost-1.61
 version, where as it is giving correct results in Boost-1.55 version.
 Here i am attaching the code snippet

 {{{
 #include <boost/geometry/geometries/point_xy.hpp>
 #include <boost/geometry/geometries/polygon.hpp>
 #include <boost/geometry.hpp>

 typedef boost::geometry::model::d2::point_xy<double> point;
 typedef boost::geometry::model::ring<point> ring;
 typedef boost::geometry::model::polygon<point> Polygon;

 int main()
 {
     Polygon p1;
     Polygon p2;
     ring r1;
     ring r2;

     r1.push_back(point(0.112, -105.2361));
     r1.push_back(point(-0.6946, -53.2131));
     r1.push_back(point(-0.2526, 0.9022));
     r1.push_back(point(86.4137, 0.8264));
     r1.push_back(point(179.5712, 0.0198));
     r1.push_back(point(180.78110000, -51.1967));
     r1.push_back(point(182.3942, -104.4295));
     r1.push_back(point(90.0432, -104.8328));
     r1.push_back(point(0.112, -105.2361));

     p1.outer() = r1;

     boost::geometry::correct(p1);
     r1.clear();

     r1.push_back(point(-10.7918213256483, 54.2140961455332));
     r1.push_back(point(113.309785590778, -17.5321453530258));
     r1.push_back(point(17.8097208933718, -86.8545273414985));
     r1.push_back(point(-72.8426247838616, -20.4407767651296));
     r1.push_back(point(-10.7918213256483, 54.2140961455332));

     r2.push_back(point(33.8071936599424, 20.2800630043229));
     r2.push_back(point(-28.7283817002881, -38.3773371397694));
     r2.push_back(point(12.4772299711817, -63.1007041426512));
     r2.push_back(point(64.8325953890491, 4.28259023775226));
     r2.push_back(point(33.8071936599424, 20.2800630043229));

     p2.inners().push_back(r2);
     p2.outer() = r1;

     boost::geometry::correct(p2);

     std::vector<Polygon> intersections;
     boost::geometry::intersection(p1, p2, intersections);

     return 0;
 }
 }}}

 The 2nd point in the intersection result i.e 1st index in "interesections"
 is wrong.

 there is a difference of (0.00002) which will reduce the accuracy in
 computations.

 Boost-1.55 version:
 intersections[1] = (-0.66354193, -55.21624099)

 Boost-1.61 version:
 intersections[1] = (-0.66356150523, -55.216229256)

-- 
Ticket URL: <https://svn.boost.org/trac10/ticket/13510>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.