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.

[sumanth.kaliki@…]

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)