原文

投影转经纬度

private IPoint PRJtoGCS( double x, double y){    IPoint pPoint = new PointClass();    pPoint.PutCoords(x, y);    ISpatialReferenceFactory pSRF = new SpatialReferenceEnvironmentClass();    pPoint.SpatialReference = pSRF.CreateProjectedCoordinateSystem( 2414 );pPoint.Project(pSRF.CreateGeographicCoordinateSystem(( int )esriSRGeoCSType.esriSRGeoCS_Beijing1954));    return pPoint;}

 

其中，pPoint.SpatialReference = pSRF.CreateProjectedCoordinateSystem( 2414 );

这行代码是设置pPoint 的空间参考，也就是要转化的点的投影坐标。如果不知道投影坐标的话，转化会报异常。

2414 为该投影的enum 值

pPoint.Project(pSRF.CreateGeographicCoordinateSystem(( int )esriSRGeoCSType.esriSRGeoCS_Beijing1954));

将该点的投影坐标转化为经纬度。

 

经纬度到投影：

private IPoint GCStoPRJ(IPoint pPoint, int GCSType, int PRJType){    ISpatialReferenceFactory pSRF = new SpatialReferenceEnvironmentClass();    pPoint.SpatialReference = pSRF.CreateGeographicCoordinateSystem(GCSType);    pPoint.Project(pSRF.CreateProjectedCoordinateSystem(PRJType));    return pPoint;}