c++ - 多边形中的 boost 点给出错误结果？

Question

我有以下单元测试，两项检查都失败:

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:

我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。我做错了什么，还是我发现了 boost 中的错误？

Answer 1

问题是由您使用的多边形类型与您提供的多边形数据不匹配引起的。通过使用 boost::geometry::model::polygon<point_type> 您创建了一个具有 point_type 的多边形作为它的点类型，它具有顺时针方向，即 关闭 和其他一些由默认模板参数配置的东西。在您提供的数据中，第一个点不等于最后一个点(这是此上下文中 closed 的定义)。你可以，make your polygon not be closed ( polygon<point_type,true,false> )或 make sure that your first and last points are equal (by copying the first point at the end) .

编辑:另一种(可能更好的)方法可能是使用 boost::geometry::correct(poly);无需更改任何其他内容(非常有趣)answer .