1 IPoint pointStart = new PointClass(); 2 pointStart = xyPolyline.FromPoint; 3 4 ISpatialReferenceFactory pSpatialRefFtry = new SpatialReferenceEnvironmentClass(); 5 ISpatialReference fromSpatialRef = pSpatialRefFtry.CreateESRISpatialReferenceFromPRJFile(Application.StartupPath + "\CoordinateSystems\2000_3_Degree_117E.prj"); 6 ISpatialReference toSpatialRef = pSpatialRefFtry.CreateESRISpatialReferenceFromPRJFile(Application.StartupPath + "\CoordinateSystems\China Geodetic Coordinate System 2000.prj"); 7 ISpatialReferenceFactory pSRF = new SpatialReferenceEnvironmentClass(); 8 pointStart.SpatialReference = fromSpatialRef; 9 pointStart.Project(toSpatialRef);