多边形中的增强点给出错误结果？

Question

我有以下单元测试，两项检查都失败了失败：

BOOST_AUTO_TEST_CASE(test_point_in_polygon)
{
    typedef boost::geometry::model::d2::point_xy<double> point_type;
    boost::geometry::model::polygon<point_type> poly;
    boost::geometry::read_wkt("POLYGON((-57.0635 -3.58045, -57.8088 -4.75336, -56.7036 -7.65533, -56.4646 -9.08261, -55.219 -9.42072, -54.6047 -9.54237, -53.868 -9.22164, -52.4139 -8.58345, -49.4691 -6.94159, -49.2295 -6.87687, -47.1079 -6.18013, -45.9159 -5.91411, -43.7897 -5.89581, -42.285 -5.95883, -40.1693 -6.38999, -38.1374 -6.87424, -35.7062 -7.67065, -34.6193 -8.40713, -34.1769 -8.74957, -31.785 -9.31504, -30.574 -9.70903, -26.909 -10.5865, -24.9817 -11.268, -22.6134 -12.2833, -21.0927 -13.3427, -20.006 -13.7029, -16.8407 -15.2466, -13.2203 -16.816, -11.3922 -17.4133, -10.7577 -17.6366, -8.54581 -18.2736, -7.18058 -18.6037, -4.86031 -19.0997, -4.25834 -19.3046, -3.39545 -19.3122, -0.985195 -19.7047, -0.340967 -19.9409, 0.75209 -19.8968, 3.30498 -20.3562, 6.82228 -20.6405, 10.4384 -20.5995, 13.8557 -20.2595, 14.7523 -20.1371, 18.3468 -19.4284, 18.9915 -19.4505, 22.5377 -18.5053, 23.2192 -18.4658, 26.4885 -17.3378, 27.2915 -17.2273, 30.5962 -15.8816, 32.7278 -14.6911, 33.8878 -14.1893, 36.2752 -12.7482, 38.5306 -11.1893, 40.8465 -9.28305, 41.1732 -9.05935, 43.372 -7.07535, 45.2436 -5.2073, 46.9925 -3.21699, 48.616 -1.35438, 50.628 0.592424, 52.158 1.37445, 53.1148 2.07603, 50.9152 5.07491, 50.3177 6.38521, 49.9412 7.3891, 48.8311 9.29466, 47.7653 12.692, 45.6416 16.3693, 43.7106 17.9319, 41.4998 17.9314, 37.4335 19.4761, 34.3477 18.4887, 32.1299 18.0676, 29.2684 18.0666, 26.5269 15.0811, 19.7706 14.5304, 15.8916 12.9664, 14.8124 12.5622, 12.783 10.0368, 12.4488 9.65713, 11.1008 7.47097, 8.9187 5.4486, 5.63935 1.10272, -6.34225 4.45488, -8.60563 7.7494, -16.2454 11.2148, -23.399 18.8388, -25.8497 20.2781, -28.8931 22.7068, -31.4379 22.8942, -32.5636 21.9563, -35.2968 20.2469, -37.3132 19.0133, -37.9703 18.2828, -40.4433 15.553, -40.9543 14.1728, -42.8783 10.3486, -46.3297 7.28714, -48.959 5.88183, -52.1939 2.65934, -54.8196 -0.896786))", poly);

    point_type point (-57.8088, -1.5755);
    BOOST_CHECK_EQUAL(boost::geometry::within(point, poly), false);

    point = point_type(-100, -2);
    BOOST_CHECK_EQUAL(boost::geometry::within(point, poly), false);

}

数据如下所示：

我正在以与文档类似的方式使用它 (http://www.boost.org/doc/libs/1_61_0/libs/geometry/doc/html/geometry/reference/algorithms/within/within_2.html)。

如图，很明显两个点都在多边形之外。是我做错了什么，还是我发现了 boost 中的错误？

Answer 1

问题是由于您使用的多边形类型与您提供的多边形数据不匹配造成的。通过使用 boost::geometry::model::polygon<point_type> you create a polygon that has point_type as its point type, that has clockwise direction, that is closed and several other things that are configured by the default template parameters. In the data you provide the first point is not equal to the last one (this is the definition of closed in this context). You can either, make your polygon not be closed (polygon<point_type,true,false>) or make sure that your first and last points are equal (by copying the first point at the end).

编辑：另一种（可能更好）方法可以使用 boost::geometry::correct(poly); 而无需更改任何其他内容，如本（非常有趣）answer.

所示

多边形中的增强点给出错误结果？

Boost point in polygon giving erroneous results?

c++

boost

boost-geometry