添加引用：NetTopologySuite、ProjNet、ProjNet.SRID

Program.cs文件：

using ProjNet.CoordinateSystems;
using ProjNet.CoordinateSystems.Transformations;
using ProjNet.SRID;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Xsl;
using NetTopologySuite.IO;
using NetTopologySuite.Geometries;namespace Reproject2
{internal class Program{static void Main(string[] args){CoordinateSystem projCs = SRIDReader.GetCSbyID(4527);CoordinateSystem geoCs = SRIDReader.GetCSbyID(4490);CoordinateTransformationFactory ctFactory = new CoordinateTransformationFactory();ICoordinateTransformation transformation = ctFactory.CreateFromCoordinateSystems(projCs, geoCs);Polygon original = new Polygon(new LinearRing(new Coordinate[] {new Coordinate(39498340.1151, 4807100.9600),new Coordinate(39499340.1151, 4809100.9600),new Coordinate(39497340.1151, 4806100.9600),new Coordinate(39498340.1151, 4807100.9600)}));foreach (var coor in original.Coordinates){Console.WriteLine("原始坐标: " + coor.X + " ; " + coor.Y);}Geometry after = Transform(original, transformation.MathTransform);foreach (var coor in after.Coordinates){Console.WriteLine("转换后坐标: " + coor.X + " ; " + coor.Y);}Console.ReadKey();}public static Geometry Transform(Geometry geometry, MathTransform mathTransform){geometry = geometry.Copy();geometry.Apply(new MathTransformFilter(mathTransform));return geometry;}}
}

新增文件：MathTransformFilter.cs，用于完成任意geometry的序列化转坐标。

using NetTopologySuite.Geometries;
using ProjNet.CoordinateSystems.Transformations;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Reproject2
{public class MathTransformFilter : ICoordinateSequenceFilter{private readonly MathTransform _mathTransform;public MathTransformFilter(MathTransform mathTransform)=> _mathTransform = mathTransform;public bool Done => false;public bool GeometryChanged => true;public void Filter(CoordinateSequence seq, int i){var (x, y, z) = _mathTransform.Transform(seq.GetX(i), seq.GetY(i), seq.GetZ(i));seq.SetX(i, x);seq.SetY(i, y);seq.SetZ(i, z);}}
}