Problems with 180 and -180 meridian, using bg::cs::geographic<bg::degree>

[ostroukhov@…]

While calculating the envelope:

#include <boost/range.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/geometry/geometries/concepts/ring_concept.hpp>
#include <boost/geometry/geometries/register/ring.hpp>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/geometries.hpp>


namespace bg = boost::geometry;
namespace bgi = boost::geometry::index;

    typedef bg::model::point<double, 2, bg::cs::geographic<
            bg::degree>> point_t;
        typedef bg::model::ring<point_t> ring_t;

    ring_t ring {{-180, 0}, {180, 0}, {180, -85}, {-180, -85}, {-180, 0}};

    auto aabb = bg::return_envelope< bg::model::box<point_t> >(ring);

    std::cout << "max_corner lon ="
             << aabb.max_corner().get<0>();
    std::cout << "min_corner lon ="
             << aabb.min_corner().get<0>();

It prints both max_corner and min_corner longitude as 180

[awulkiew]

It's because in spherical and geographic coordinate systems degrees -180 and 180 are the same longitude. The Geometry you created is segment-like Ring (invalid, with area = 0) lying on antimeridian so the envelope of this Ring should be BOX(180 -85, 180 0). Or am I missing something?