C# NetTopologySuite M值

Question

我正在使用NetTopologySuite作为SqlGeometries的.net核心替代品。它似乎不支持点或坐标中的M值，尽管它有M个属性。例如这段简单的代码：

using NetTopologySuite.Geometries;
using System.Diagnostics;

namespace PlaygroundCore
{
    class Program
    {
        static void Main(string[] args)
        {
            var p3 = new Point(1, 2, 3);
            p3.Y = 8;
            p3.M = 1;
            var m = p3.M;

            Debug.WriteLine(p3);
            Debug.WriteLine(p3.M);
            Debug.WriteLine(m);
        }
    }
}

输出

POINT (1 8 3)
NaN
NaN

M值似乎完全被拒绝了。这是实现中的一个bug吗？有没有办法用M值创建点/坐标/线串？

Answer 1

默认坐标序列是CoordinateArraySequence，它当前不支持M值，但看起来DotSpatialAffineCoordinateSequence确实支持M值。要使M值正常工作，我必须执行以下操作

using NetTopologySuite.Geometries;
using NetTopologySuite.Geometries.Implementation;
using System.Diagnostics;

namespace NetTopologyTest
{
    class Program
    {
        static void Main(string[] args)
        {
            //This sequence has to be initialized with ordinates XYZM. If you construct it
            //with just XYZ values, then you can't add M values to it later.
            var coordinateSequence = new DotSpatialAffineCoordinateSequence(new[] { 1.0, 2.0 }, new[] { 3.0 }, new[] { 4.0 });
            var sequenceFactory = new DotSpatialAffineCoordinateSequenceFactory(GeoAPI.Geometries.Ordinates.XYZM);
            var geometryFactory = new GeometryFactory(sequenceFactory);
            var p3 = new Point(coordinateSequence, geometryFactory);
            p3.Y = 8;
            p3.M = 1;
            var m = p3.M;

            Debug.WriteLine(p3);
            Debug.WriteLine(p3.M);
            Debug.WriteLine(m);
        }
    }
}