How to use the IAffineTransformation2D project and MoveOrigin methods

Using the IAffineTransformation2D project and MoveOrigin methods

1. Create two spatial references, one for the geographic coordinate system (GCS) and one for the projected coordinate system (PCS).
2. Create a point.
3. Project the point from the GCS to the PCS.
4. Query interface (QI) the point to ITransform2D.
5. Set up an AffineTransformation.
6. Call Transform on ITransform2D.

[C#]

public void Driver()
{
    Test( - 122, 37);
    // MoveOrigin is at a slightly different location: Yields slightly inaccurate results.
    Test( - 125, 35);
}

private void Test(double originX, double originY)
{
    //Set up spatial references.

    Type factoryType=Type.GetTypeFromProgID(
        "esriGeometry.SpatialReferenceEnvironment");
    System.Object obj=Activator.CreateInstance(factoryType);
    ISpatialReferenceFactory3 spatialReferenceFactory=obj as
        ISpatialReferenceFactory3;

    ISpatialReference fromSpatialReference =
        spatialReferenceFactory.CreateGeographicCoordinateSystem((int)
        esriSRGeoCSType.esriSRGeoCS_NAD1983);
    ISpatialReference toSpatialReference =
        spatialReferenceFactory.CreateProjectedCoordinateSystem((int)
        esriSRProjCSType.esriSRProjCS_NAD1983UTM_10N);
    //Set up a point for transforming.
    IPoint point=new ESRI.ArcGIS.Geometry.Point();
    point.PutCoords( - 122, 37);
    point.SpatialReference=fromSpatialReference;
    point.Project(toSpatialReference);
    ITransform2D transformator=point as ITransform2D;
    //Set up the comparison point.
    //This is the point the transformation should result in.
    IPoint comparisonPoint=new ESRI.ArcGIS.Geometry.Point();
    comparisonPoint.PutCoords( - 121, 42);
    comparisonPoint.SpatialReference=fromSpatialReference;
    comparisonPoint.Project(toSpatialReference);
    //Transform.
    //Set up the affine transformation.
    //MoveOrigin is at the same location as the Point to be transformed: Yields accurate results.
    IAffineTransformation2D2 affineTranformation=new AffineTransformation2D()as
        IAffineTransformation2D2;
    affineTranformation.Move(1, 5);
    ESRI.ArcGIS.Geometry.Point origin=new ESRI.ArcGIS.Geometry.Point();
    origin.PutCoords(originX, originY);
    affineTranformation.MoveOrigin=origin;
    affineTranformation.SpatialReference=fromSpatialReference;
    affineTranformation.Project(toSpatialReference);
    //Transform and report results.
    System.Windows.Forms.MessageBox.Show("A2D XTrans: " +
        affineTranformation.XTranslation + ", YTrans: " +
        affineTranformation.YTranslation + "\n" + "A2D MoveOrigin X: " +
        affineTranformation.MoveOrigin_2.X + ", Y: " +
        affineTranformation.MoveOrigin_2.Y + "\n" + "Before Trans, Point X:" +
        point.X + ", Y:" + point.Z);
    transformator.Transform(esriTransformDirection.esriTransformForward,
        affineTranformation);
    System.Windows.Forms.MessageBox.Show("After Trans, Point X:" + point.X + ", Y:" 
        + point.Y + "\n" + "Comparison, Point X:" + comparisonPoint.X + ", Y:" +
        comparisonPoint.Y + "\n" + "Did X coordinates match? " + (point.X ==
        comparisonPoint.X) + "\n" + "Did Y coordinates match? " + (point.Y ==
        comparisonPoint.Y));
}

[VB.NET]

Private Sub TestMove()
    'Set up spatial references.
    
    Dim t As Type=Type.GetTypeFromProgID("esriGeometry.SpatialReferenceEnvironment")
    Dim obj As System.Object=Activator.CreateInstance(t)
    Dim pSpatialReferenceEnv As ESRI.ArcGIS.Geometry.ISpatialReferenceFactory3=obj
    
    Dim pFromSR As ISpatialReference
    pFromSR=pSpatialReferenceEnv.CreateGeographicCoordinateSystem(esriSRGeoCSType.esriSRGeoCS_NAD1983)
    Dim pToSR As ISpatialReference
    pToSR=pSpatialReferenceEnv.CreateProjectedCoordinateSystem(esriSRProjCSType.esriSRProjCS_NAD1983UTM_10N)
    'Set up a point for transforming.
    Dim pPt As IPoint
    Dim pT2D As ITransform2D
    pPt=New Point
    pPt.PutCoords( -122, 37)
    pPt.SpatialReference=pFromSR
    pPt.Project(pToSR)
    pT2D=pPt
    'Set up the comparison point.
    'This is the point the transformation should result in.
    Dim pPt2 As IPoint
    pPt2=New Point
    pPt2.PutCoords( -121, 42)
    pPt2.SpatialReference=pFromSR
    pPt2.Project(pToSR)
    'Transform.
    Dim pA2D2 As IAffineTransformation2D2
    Dim pA2D As IAffineTransformation2D2
    Dim pOrigin As IPoint
    ' Set up the affine transformation.
    ' MoveOrigin is at the same location as the point to be transformed: Yields accurate results.
    pA2D2=New AffineTransformation2D
    pA2D2.Move(1, 5)
    pA2D=pA2D2
    pOrigin=New Point
    pOrigin.PutCoords( -122, 37)
    pA2D.MoveOrigin=pOrigin
    pA2D.SpatialReference=pFromSR
    pA2D.Project(pToSR)
    ' Transform and report results.
    Debug.Print("----Using MoveOrigin at the same location as the Point to be transformed----")
    Debug.Print("A2D XTrans: " & pA2D.XTranslation & ", YTrans: " & pA2D.YTranslation)
    Debug.Print("A2D MoveOrigin X: " & pA2D2.MoveOrigin_2.X & ", Y: " & pA2D2.MoveOrigin_2.Y)
    Debug.Print("Before Trans, Point X:" & pPt.X & ", Y:" & pPt.Y)
    pT2D.Transform(esriTransformDirection.esriTransformForward, pA2D)
    Debug.Print("After Trans, Point X:" & pPt.X & ", Y:" & pPt.Y)
    Debug.Print("Comparison, Point X:" & pPt2.X & ", Y:" & pPt2.Y)
    Debug.Print("Did X coordinates match? " & (pPt.X=pPt2.X))
    Debug.Print("Did Y coordinates match? " & (pPt.Y=pPt2.Y))
    ' Set up the affine transformation.
    ' MoveOrigin is at a slightly different location: Yields slightly inaccurate results.
    pA2D2=New AffineTransformation2D
    pA2D2.Move(1, 5)
    pA2D=pA2D2
    pOrigin=New Point
    pOrigin.PutCoords( -125, 35)
    pA2D.MoveOrigin=pOrigin
    pA2D.SpatialReference=pFromSR
    pA2D.Project(pToSR)
    ' Set up a point for transforming.
    pPt=New Point
    pPt.PutCoords( -122, 37)
    pPt.SpatialReference=pFromSR
    pPt.Project(pToSR)
    pT2D=pPt
    ' Transform and report results.
    Debug.Print("----Using MoveOrigin at a slightly different location----")
    Debug.Print("A2D XTrans: " & pA2D.XTranslation & ", YTrans: " & pA2D.YTranslation)
    Debug.Print("A2D MoveOrigin X: " & pA2D2.MoveOrigin_2.X & ", Y: " & pA2D2.MoveOrigin_2.Y)
    Debug.Print("Before Trans, Point X:" & pPt.X & ", Y:" & pPt.Y)
    pT2D.Transform(esriTransformDirection.esriTransformForward, pA2D)
    Debug.Print("After Trans, Point X:" & pPt.X & ", Y:" & pPt.Y)
    Debug.Print("Comparison, Point X:" & pPt2.X & ", Y:" & pPt2.Y)
    Debug.Print("Did X coordinates match? " & (pPt.X=pPt2.X))
    Debug.Print("Did Y coordinates match? " & (pPt.Y=pPt2.Y))
End Sub

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To use the code in this topic, reference the following assemblies in your Visual Studio project. In the code files, you will need using (C#) or Imports (VB .NET) directives for the corresponding namespaces (given in parenthesis below if different from the assembly name):

• ESRI.ArcGIS.Geometry

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