我正在尝试将英国Northing/Eastings坐标系(BritishNationalGridOSGB36)的shapefile读入经度/纬度(WGS1984)。关于如何使用NetTopologySuite执行此操作,我发现了一篇优秀的文章here。 shapefile的读取工作正常,但在加载期间转换地理位置时出现问题。使用NetTopologySuite时发生错误TransformGeometry
我已将问题归结为NetTopologySuite TransformGeometry方法。如果我使用DotSpatial ReprojectPoints转换点,它可以正常工作(一旦我对BritishNationalGridOSGB36有正确的定义,请参阅here以获取有用的文章)。但是NetTopologySuite的TransformGeometry给了我一个错误的答案。答案是错在两个方面
- 它在经度纬度值(应该是-0.095399303)
- 纬度181560(应该是51.517489)
我想用NetTopologySuite的TransformGeometry在处理几何图形时要比拆除每个坐标并更改它好得多。我也认为我一定做了一些事情,所以我想修复它并学习。
这是我的NUNIT测试代码。
class TestConvert
{
//The standard DotSpatial definition, KnownCoordinateSystems.Projected.NationalGrids.BritishNationalGridOSGB36, is incorrect so needed defined string below
const string BritishNationalGridOsgb36String = "+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894 +units=m +no_defs";
readonly ProjectionInfo _britishNationalGridOsgb36 = ProjectionInfo.FromProj4String(BritishNationalGridOsgb36String);
readonly ProjectionInfo _wgs84 = KnownCoordinateSystems.Geographic.World.WGS1984;
[Test]
public void ConvertAPointUsingDotSpatialReproject()
{
//SETUP
var xy = new double[] { 532248.29992272425, 181560.30052819476 };
var z = new double[] { 0 };
//ATTEMPT
Reproject.ReprojectPoints(xy, z,
_britishNationalGridOsgb36, _wgs84, 0, z.Length);
//VERIFY
xy[0].ShouldEqualWithTolerance(-0.095399303, 0.001);
xy[1].ShouldEqualWithTolerance(51.517489, 0.001);
}
[Test]
public void ConvertAPointUsingNetTopologySuiteTransformGeometry()
{
//SETUP
var factory = NetTopologySuite.Geometries.GeometryFactory.Default;
var pointNatGrid = new NetTopologySuite.Geometries.Point(532248.29992272425, 181560.30052819476);
//ATTEMPT
var transform = new DotSpatialMathTransform(
_britishNationalGridOsgb36, _wgs84);
var result = GeometryTransform.TransformGeometry(
factory, pointNatGrid, transform);
//VERIFY
result.GeometryType.ShouldEqual("Point");
result.Coordinates.Count().ShouldEqual(1);
result.Coordinates[0].X.ShouldEqualWithTolerance(-0.095399303, 0.001);
result.Coordinates[0].Y.ShouldEqualWithTolerance(51.517489, 0.001);
}
}
第一次测试通过,第二次测试在两个ShouldEqualWithTolerance测试上都失败。
您的帮助,将不胜感激。