// 同一椭球下经纬度坐标、平面的坐标互转
private IPoint GetpProjectPoint(IPoint pPoint, bool pBool)

 {

     ISpatialReferenceFactory pSpatialReferenceEnvironemnt = new SpatialReferenceEnvironment();

     ISpatialReference pFromSpatialReference = pSpatialReferenceEnvironemnt.CreateGeographicCoordinateSystem((int)esriSRGeoCS3Type.esriSRGeoCS_Xian1980);//西安80

     ISpatialReference pToSpatialReference = pSpatialReferenceEnvironemnt.CreateProjectedCoordinateSystem((int)esriSRProjCS4Type.esriSRProjCS_Xian1980_3_Degree_GK_Zone_34);//西安80

     if (pBool == true)//球面转平面

        {

            Geometry pGeo = (IGeometry)pPoint;

            pGeo.SpatialReference = pFromSpatialReference;

            pGeo.Project(pToSpatialReference);

            return pPoint;

        }

        else //平面转球面

        {

        IGeometry pGeo = (IGeometry)pPoint;

        pGeo.SpatialReference = pToSpatialReference;

        pGeo.Project(pFromSpatialReference);

        return pPoint;

        }

}

// 不同基准面之间的坐标转换 WGS1984 GaussKruger -- >  esriSRProjCS_Xian1980_GK_Zone_19
public void ProjectExExample()

{

    ISpatialReferenceFactory pSpatialReferenceFactory = new SpatialReferenceEnvironmentClass();  // ISpatialReference pFromCustom = pSpatialReferenceFactory.CreateESRISpatialReferenceFromPRJFile(@"E:\arcgis\Engine\z idingyi.prj");

    IPoint pFromPoint = new PointClass();

    pFromPoint.X = 518950.788;

    pFromPoint.Y = 4335923.97;

    IZAware pZAware = pFromPoint as IZAware;

    pZAware.ZAware = true;

    pFromPoint.Z = 958.4791;  // 自定义投影WGS84下的北京6度 19带。

    ((IGeometry)pFromPoint).SpatialReference = CreateCustomProjectedCoordinateSystem();  // ((IGeometry)pFromPoint).SpatialReference = pFromCustom; 


    //目标投影

    IProjectedCoordinateSystem projectedCoordinateSystem = pSpatialReferenceFactory.CreateProjectedCoordinateSystem((int)esriSRProjCS4Type.esriSRProjCS_Xian1980_GK_Zone_19);             //因为目标基准面和原始基准面不在同一个上，所以牵扯到参数转换，我用7参数 转换             ICoordinateFrameTransformation   pCoordinateFrameTransformation = new CoordinateFrameTransformationClass();
pCoordinateFrameTransformation.PutParameters(-112.117, 4.530, 21.89, -0.00058702, -0.00476421, 0.00009358, 0.99998006411);
pCoordinateFrameTransformation.PutSpatialReferences(CreateCustomProjectedCoordinateSystem(), projectedCoordinateSystem as ISpatialReference);                       

    //投影转换

    IGeometry2 pGeometry = pFromPoint as IGeometry2;
pGeometry.ProjectEx(projectedCoordinateSystem as ISpatialReference, esriTransformDirection.esriTransformForward, pCoordinateFrameTransformation, false, , );

}

private IProjectedCoordinateSystem CreateCustomProjectedCoordinateSystem()

{

    ISpatialReferenceFactory2 pSpatialReferenceFactory = new SpatialReferenceEnvironmentClass();

    IProjectionGEN pProjection = pSpatialReferenceFactory.CreateProjection((int)esriSRProjectionType.esriSRProjection_GaussKruger) as IProjectionGEN; 
    IGeographicCoordinateSystem pGeographicCoordinateSystem = pSpatialReferenceFactory.CreateGeographicCoordinateSystem((int)esriSRGeoCSType.esriSRGeoCS_WGS1984);

    ILinearUnit pUnit = pSpatialReferenceFactory.CreateUnit((int)esriSRUnitType.esriSRUnit_Meter) as ILinearUnit;

    IParameter[] pParameters = pProjection.GetDefaultParameters();

    IProjectedCoordinateSystemEdit pProjectedCoordinateSystemEdit = new ProjectedCoordinateSystemClass();

    object pName = "WGS-BeiJing1954";

    object pAlias = "WGS-BeiJing1954";

    object pAbbreviation = "WGS-BeiJing1954";

    object pRemarks = "WGS-BeiJing1954";

    object pUsage = "Calculate Meter From lat and lon";

    object pGeographicCoordinateSystemObject = pGeographicCoordinateSystem as object;

    object pUnitObject = pUnit as object;

    object pProjectionObject = pProjection as object;

    object pParametersObject = pParameters as object;

    pProjectedCoordinateSystemEdit.Define(ref pName, ref pAlias, ref pAbbreviation, ref  pRemarks, ref pUsage, ref pGeographicCoordinateSystemObject, 
        ref pUnitObject, ref pProjectionObject, ref pParametersObject);

    IProjectedCoordinateSystem5 pProjectedCoordinateSystem = pProjectedCoordinateSystemEdit as IProjectedCoordinateSystem5;

    pProjectedCoordinateSystem.FalseEasting = ;

    pProjectedCoordinateSystem.LatitudeOfOrigin = ;

    pProjectedCoordinateSystem.set_CentralMeridian(true, );

    pProjectedCoordinateSystem.ScaleFactor = ;

    pProjectedCoordinateSystem.FalseNorthing = ;

    return pProjectedCoordinateSystem;

}