使用AE进行点的坐标投影变换

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

其中，

pPoint.SpatialReference = pSRF.CreateProjectedCoordinateSystem(  );

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，如果要查询坐标系的WKID，请点击地理坐标系：www.cnblogs.com/hyqing/p/3660611.html和投影坐标系www.cnblogs.com/hyqing/p/3660662.html

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;
} 

如果出现：无法嵌入互操作类型提示，右键点击引入的AE库，将其属性中的“嵌入互操作类型”改为False