ArcEngine 座標系轉換

/// <summary>
/// 地理座標系 轉 投影座標系
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="GCSType">地理座標系編號</param>
/// <param name="PRJType">投影座標系編號</param>
/// <returns></returns>
private IPoint GCStoPRJ(double x, double y, int GCSType, int PRJType)
{
    IPoint pPoint = new PointClass();
    pPoint.PutCoords(x, y);
    ISpatialReferenceFactory pSRF = new SpatialReferenceEnvironmentClass();
    pPoint.SpatialReference = pSRF.CreateGeographicCoordinateSystem(GCSType);
    //GCS_WGS_1984 WKID: 4326 權限: EPSG
    pPoint.Project(pSRF.CreateProjectedCoordinateSystem(PRJType));
    //Xian_1980_3_Degree_GK_CM_114E  WKID: 2383 權限: EPSG
    return pPoint;
}

/// <summary>
/// 投影座標系 轉 地理座標系
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="GCSType">地理座標系編號</param>
/// <param name="PRJType">投影座標系編號</param>
/// <returns></returns>
private IPoint PRJtoGCS(double x, double y,int GCSType, int PRJType)
{
    IPoint pPoint = new PointClass();
    pPoint.PutCoords(x, y);
    ISpatialReferenceFactory pSRF = new SpatialReferenceEnvironmentClass();
    pPoint.SpatialReference = pSRF.CreateProjectedCoordinateSystem(PRJType);
    pPoint.Project(pSRF.CreateGeographicCoordinateSystem(GCSType));            
    return pPoint;
}