Dear Boost Geometry Contributors,
I am testing the boost::geometry::dissolve function upon some invalid
polygons that are produced by a certain in-house segmentation alg.
The fact that the algorithm is producing possibly invalid polygons cannot be
changed easily so I thought I will fix them afterwards using dissolve from
“geometry/extensions/algorithms/dissolve.hpp” for the latest boost 1.58 version.
Unfortunately I stumbled over the following polygons for which dissolve
produces wrong results.
The following code illustrates the result
using namespace boost::geometry;
using namespace boost::geometry::model;
using namespace boost::geometry::model::d2;
int
main(int argc, _TCHAR* argv[])
{
polygon< point_xy<float> > Poly;
read_wkt("POLYGON((10 10, 10 20, 20 20, 15 12, 15 18, 20 10, 10 10))",
Poly);
multi_polygon< polygon< point_xy< float > > > Dissolved;
boost::geometry::dissolve(Poly, Dissolved);
}
Which results in a polygon including the small intersection part which
should be excluded from the polygon
And even more problematic the following example (same polygon with and
additional self-touching outer ring) results in missing the entire main part
of the polygon
int
main(int argc, _TCHAR* argv[])
{
polygon< point_xy<float> > Poly;
read_wkt("POLYGON((10 10, 10 20, 20 20, 20 25, 22 25, 20 20, 15 12, 15
18, 20 10, 10 10))",
Poly);
multi_polygon< polygon< point_xy< float > > > Dissolved;
boost::geometry::dissolve(Poly, Dissolved);
}
I hope somebody can show me what I did wrong or what I can to too work
around this problem.
Best regards,
Andreas Wimmer
