
Geometry : 
Subject: Re: [geometry] Trouble with polygon/box intersection when polygon/box point types are different
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 20160523 19:54:52
Gratton, Michael wrote:
> Hello,
>
> I'm trying to adapt polygons using Eigen::Vector2d point types (http://eigen.tuxfamily.org) for use with boost::geometry. Things mostly work great, but the rtree implementation uses the internal boost::geometry box type, and I get errors when attempting to intersect my Eigen polygon with the internal box.
Hi Michael,
Thanks for the info about the bug.
This bug was reported recently:
https://svn.boost.org/trac/boost/ticket/12189
See also a discussion (workaround):
http://boostgeometry.203548.n3.nabble.com/RtreespacialpredicatesintersectsRinginboost159upwardstd4026700.html
Regards,
Adam
> I made a small program to isolate the compilation error I get:
>
> %<
> #include <Eigen/Core>
> #include <Eigen/StdVector>
> #include <Eigen/Geometry>
> #include <boost/geometry/geometries/register/point.hpp>
> #include <boost/geometry/geometries/register/box.hpp>
> #include <boost/geometry/geometries/register/ring.hpp>
> #include <boost/geometry/geometries/register/linestring.hpp>
> #include <boost/geometry/geometries/geometries.hpp>
> #include <boost/geometry.hpp>
>
> using Eigen::Vector2d;
> typedef std::vector<Vector2d, Eigen::aligned_allocator<Vector2d> > EigenVector2d;
>
> BOOST_GEOMETRY_REGISTER_POINT_2D(Vector2d, double, cs::cartesian, coeffRef(0), coeffRef(1))
> BOOST_GEOMETRY_REGISTER_LINESTRING(EigenVector2d)
> BOOST_GEOMETRY_REGISTER_BOX(Eigen::AlignedBox2d, Vector2d, min(), max());
>
> typedef boost::geometry::model::polygon<
> Vector2d, // Point type
> true, // Orientation is counterclockwises in NED sense (southeastnorthwest)
> false, // Closure is implied (last point != first point)
> std::vector, // Store for points (efficient if all points known in advance)
> std::vector, // Store for rings (efficient if all holes known in advance)
> Eigen::aligned_allocator // Need to allocate Vector2d with special allocator
> >
> EigenPolygon;
>
>
> int main(int argc, char** argv)
> {
> namespace bg = boost::geometry;
> EigenVector2d point(3);
> point[0] << 0.5, 0.5;
> point[1] << 0.5, 6.0;
> point[2] << 1.0, 2.0;
> EigenPolygon poly;
> bg::append(poly, point);
> Vector2d ll(0,0);
> Vector2d ur(5.0,5.0);
> Eigen::AlignedBox2d box(ll, ur);
> std::cout << "poly intersect box? " << bg::intersects(poly, box) << "\n";
> bg::model::box<bg::model::point<double, 2ul, bg::cs::cartesian> > bbox;
> bbox.min_corner().set<0>(ll(0));
> bbox.min_corner().set<1>(ll(1));
> bbox.max_corner().set<0>(ur(0));
> bbox.max_corner().set<1>(ur(1));
> // Fails
> std::cout << "poly intersect bbox? " << bg::intersects(poly, bbox) << "\n";
> bg::model::polygon<bg::model::point<double, 2ul, bg::cs::cartesian>, true, false> poly2;
> bg::append(poly2, point);
> std::cout << "poly2 intersect bbox? " << bg::intersects(poly2, bbox) << "\n";
> // Fails
> std::cout << "poly2 intersect box? " << bg::intersects(poly2, box) << "\n";
> }
> %<
>
> I don't know if I am doing something wrong with the registration macros, but it looks okay to me. Working from the 1.60 source, I found that boost/geometry/algorithms/detail/overlay/get_turn_info_helpers.hpp_at_222 is trying to use a strategy::apply that assumes Point1 is the same type as Point2. If I change
>
> intersection_info(Point1 const& pi, Point1 const& pj, Point1 const& pk,
> Point2 const& qi, Point2 const& qj, Point2 const& qk,
> RobustPolicy const& robust_policy)
> : base(pi, pj, pk, qi, qj, qk, robust_policy)
> , m_result(strategy::apply(segment_type1(pi, pj),
> segment_type2(qi, qj),
> robust_policy,
> base::rpi(), base::rpj(),
> base::rqi(), base::rqj()))
> , m_robust_policy(robust_policy)
> {}
>
> to read
>
> intersection_info(Point1 const& pi, Point1 const& pj, Point1 const& pk,
> Point2 const& qi, Point2 const& qj, Point2 const& qk,
> RobustPolicy const& robust_policy)
> : base(pi, pj, pk, qi, qj, qk, robust_policy)
> , m_result(strategy::apply(segment_type1(pi, pj),
> segment_type2(qi, qj),
> robust_policy))
> , m_robust_policy(robust_policy)
> {}
>
> then everything builds and works. Looking inside, it looks like the later makes copies of the four points, storing them in the point type of the first segment type. So this change would be a bit of a performance hit compared to what is already there.
>
> Is this a bug or am I mixing something up with my custom polygon type?
>
> Thanks,
>
> Michael Gratton, Ph.D.  Senior Research Analyst
>
> Metron  Computing and Engineering Technologies for Unmanned Systems (CETUS) Division
>
> 1818 Library St Ste 600  Reston VA 20190
>
> 703.326.2833  gratton_at_[hidden]<mailto:gratton_at_[hidden]>
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