boost::geometry 中无效几何的数据集

Question

是否存在使用 c++ 和 boost::geometry 库的所有可能无效几何的数据集？或者至少我可以转换为 boost::geometry 的无效几何的多边形坐标 示例：自相交等 我想用至少所有可能的无效几何图形来测试我的应用程序。 像这样的：

https://knowledge.safe.com/articles/21674/invalid-ogc-geometry-examples.html

但有更多带有内部和外部多边形的测试用例。

Answer 1

Boost Geometry 库实现了 OGC 标准。来自intro

该库遵循现有约定：

• 来自Boost 的约定
• 标准库中的约定
• 来自OGC 几何标准之一的约定和名称，更具体地说，来自OGC Simple Feature Specification

所以你使用的列表是相关的。

此外，您可以使用带有reason 参数的is_valid 函数来询问有关几何图形的库。我在这个网站上有几个例子展示了如何做到这一点。 （注意：并非所有约束都可能是可验证的）

您的样品，现场直播

让我们采用样本中的外环方向（不是 BG 默认值）：

namespace bg = boost::geometry;
using pt    = bg::model::d2::point_xy<double>;
using poly  = bg::model::polygon<pt, false>;
using multi = bg::model::multi_polygon<poly>;

让我们创建一个通用检查器：

template <typename Geo = poly> void check(std::string wkt) {
    Geo g;
    bg::read_wkt(wkt, g);
    std::string reason;
    bool ok = bg::is_valid(g, reason);
    std::cout << "Valid: " << std::boolalpha << ok << " (" << reason << ")\n";

    bg::correct(g);
    if (bg::is_valid(g, reason)) {
        std::cout << "Autocorrected: " << bg::wkt(g) << "\n";
    }
}

并为所有测试用例运行它：

//Hole Outside Shell
check("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0), (15 15, 15 20, 20 20, 20 15, 15 15))");
//Nested Holes
check("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0), (2 2, 2 8, 8 8, 8 2, 2 2), (3 3, 3 7, 7 7, 7 3, 3 3))");
//Disconnected Interior
check("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0), (5 0, 10 5, 5 10, 0 5, 5 0))");
//Self Intersection
check("POLYGON((0 0, 10 10, 0 10, 10 0, 0 0))");
//Ring Self Intersection
check("POLYGON((5 0, 10 0, 10 10, 0 10, 0 0, 5 0, 3 3, 5 6, 7 3, 5 0))");
//Nested Shells
check<multi>("MULTIPOLYGON(((0 0, 10 0, 10 10, 0 10, 0 0)),(( 2 2, 8 2, 8 8, 2 8, 2 2)))");
//Duplicated Rings
check<multi>("MULTIPOLYGON(((0 0, 10 0, 10 10, 0 10, 0 0)),((0 0, 10 0, 10 10, 0 10, 0 0)))");
//Too Few Points
check("POLYGON((2 2, 8 2))");
//Invalid Coordinate
check("POLYGON((NaN 3, 3 4, 4 4, 4 3, 3 3))");
//Ring Not Closed
check("POLYGON((0 0, 0 10, 10 10, 10 0))");

输出

Live On Coliru

打印

Valid: false (Geometry has interior rings defined outside the outer boundary)
Valid: false (Geometry has nested interior rings)
Valid: false (Geometry has wrong orientation)
Valid: false (Geometry has wrong orientation)
Valid: false (Geometry has invalid self-intersections. A self-intersection point was found at (5, 0); method: t; operations: i/i; segment IDs {source, multi, ring, segment}: {0, -1, -1, 4}/{0, -1, -1, 8})
Valid: false (Multi-polygon has intersecting interiors)
Valid: false (Geometry has invalid self-intersections. A self-intersection point was found at (10, 0); method: e; operations: c/c; segment IDs {source, multi, ring, segment}: {0, 0, -1, 0}/{0, 1, -1, 0})
Valid: false (Geometry has too few points)
Valid: false (Geometry has point(s) with invalid coordinate(s))
Valid: false (Geometry is defined as closed but is open)
Autocorrected: POLYGON((0 0,10 0,10 10,0 10,0 0))

注意：bg::correct 在某些情况下可能会纠正/部分/问题，但会留下其他问题，并且此check 函数不会报告该问题。

Answer 2

我创建了一个库“boost_geometry_make_valid”，它允许纠正此数据集中描述的错误：

https://github.com/kleunen/boost_geometry_make_valid

我现在使用数据集进行测试，该库能够纠正所有提到的故障。最重要的是，从多边形中移除自相交。