ArcGIS Developer Help

IAffineTransformation2D3GEN.DefineFromControlPoints Method

Defines the best affine transformation between two sets of points. Can be used to register paper maps on a digitizer.

[Visual Basic .NET]
Public Sub DefineFromControlPoints ( _
    ByRef fromPoints As IPoint[], _
    ByRef toPoints As IPoint[] _
)

[C#]
public void DefineFromControlPoints (
    ref IPoint[] fromPoints,
    ref IPoint[] toPoints
);

[C++]
HRESULT DefineFromControlPoints(
  SAFEARRAY(IPoint)** fromPoints,
  SAFEARRAY(IPoint)** toPoints
);

[C++]
Parameters
fromPoints [in]

  fromPoints is a parameter of type SAFEARRAY(IPoint*)*
toPoints [in]

  toPoints is a parameter of type SAFEARRAY(IPoint*)*

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

[C#]

        //This example demonstrates how to use the IAffineTransformation2D3GEN.DefineFromControlPoints method
        public void transformPolygon()
        {
            //From point
            IPoint[] fromPoints = new IPoint[4];
            fromPoints[0] = CreatePoint(0, 0);
            fromPoints[1] = CreatePoint(0, 1);
            fromPoints[2] = CreatePoint(1, 1);
            fromPoints[3] = CreatePoint(1, 0);
            //To point
            IPoint[] toPoints = new IPoint[4];
            toPoints[0] = CreatePoint(10, 10);
            toPoints[1] = CreatePoint(10, 15);
            toPoints[2] = CreatePoint(15, 15);
            toPoints[3] = CreatePoint(15, 10);
            //Create polygon
            IGeometry segment1 = CreateLineXY(0, 0, 0, 1) as IGeometry;
            IGeometry segment2 = CreateLineXY(0, 1, 1, 1) as IGeometry;
            IGeometry segment3 = CreateLineXY(0, 1, 0, 0) as IGeometry;
            ISegmentCollection segmentCollection = new Polygon() as ISegmentCollection;
            object Missing = Type.Missing;
            segmentCollection.AddSegment(segment1 as ISegment, ref Missing, ref Missing);
            segmentCollection.AddSegment(segment2 as ISegment, ref Missing, ref Missing);
            segmentCollection.AddSegment(segment3 as ISegment, ref Missing, ref Missing);
            IPolygon polygon = segmentCollection as IPolygon;
            //Define the transformation
            IAffineTransformation2D3GEN affineTransformation2D = new AffineTransformation2DClass();
            affineTransformation2D.DefineFromControlPoints(ref fromPoints, ref toPoints);
            //Transform
            ITransform2D transform2D = polygon as ITransform2D;
            transform2D.Transform(esriTransformDirection.esriTransformForward, affineTransformation2D as ITransformation);
        }
        private IPoint CreatePoint(double x, double y)
        {
            IPoint point = new ESRI.ArcGIS.Geometry.Point();
            point.X = x;
            point.Y = y;
            return point;
        }
        public ILine CreateLineXY(double x1, double y1, double x2, double y2)
        {
            ILine line = new Line();
            line.FromPoint = CreatePoint(x1, y1);
            line.ToPoint = CreatePoint(x2, y2);
            return line;
        }
        public ILine CreateLine(IPoint fromPoint, IPoint toPoint)
        {
            ILine line = new Line();
            line.PutCoords(fromPoint, toPoint);
            return line;
        }

[Visual Basic .NET]

    'This example demonstrates how to use the IAffineTransformation::DefineFromControlPoints method.
    Public Sub AffTrans2D_DefFromPts()
        'From point
        Dim pPtFrom(0 To 3) As ESRI.ArcGIS.Geometry.IPoint
        pPtFrom(0) = CreatePoint(0, 0)
        pPtFrom(1) = CreatePoint(0, 1)
        pPtFrom(2) = CreatePoint(1, 1)
        pPtFrom(3) = CreatePoint(1, 0)

        'To point
        Dim pPtTo(0 To 3) As ESRI.ArcGIS.Geometry.IPoint
        pPtTo(0) = CreatePoint(10, 10)
        pPtTo(1) = CreatePoint(10, 15)
        pPtTo(2) = CreatePoint(15, 15)
        pPtTo(3) = CreatePoint(15, 10)

        'Create polygon
        Dim pSeg1 As ESRI.ArcGIS.Geometry.IGeometry
        pSeg1 = CreateLineXY(0, 0, 0, 1)

Dim pSeg2 As ESRI.ArcGIS.Geometry.IGeometry
pSeg2 = CreateLineXY(0, 1, 1, 1)

Dim pSeg3 As ESRI.ArcGIS.Geometry.IGeometry
pSeg3 = CreateLineXY(1, 1, 0, 0)

Dim pPolygon As ESRI.ArcGIS.Geometry.ISegmentCollection
pPolygon = New ESRI.ArcGIS.Geometry.Polygon

        pPolygon.AddSegment(pSeg1)
        pPolygon.AddSegment(pSeg2)
        pPolygon.AddSegment(pSeg3)

Dim pPoly As ESRI.ArcGIS.Geometry.IPolygon
pPoly = pPolygon

        'Define the transformation
        Dim pAffineTrans2D As ESRI.ArcGIS.Geometry.IAffineTransformation2D3GEN
        pAffineTrans2D = New ESRI.ArcGIS.Geometry.AffineTransformation2D

        pAffineTrans2D.DefineFromControlPoints(pPtFrom, pPtTo)
        Dim pTransform2d As ESRI.ArcGIS.Geometry.ITransform2D
        'Transform
        pTransform2d = pPolygon
        pTransform2d.Transform(ESRI.ArcGIS.Geometry.esriTransformDirection.esriTransformForward, pAffineTrans2D)
    End Sub

    Public Function CreatePoint(ByVal XVal As Double, ByVal YVal As Double) As ESRI.ArcGIS.Geometry.IPoint
        CreatePoint = New ESRI.ArcGIS.Geometry.Point
        CreatePoint.X = XVal
        CreatePoint.Y = YVal
    End Function

    Public Function CreateLineXY(ByVal X1 As Double, ByVal Y1 As Double, ByVal X2 As Double, ByVal Y2 As Double) As ESRI.ArcGIS.Geometry.ILine
        CreateLineXY = CreateLine(CreatePoint(X1, Y1), CreatePoint(X2, Y2))
    End Function

    Public Function CreateLine(ByVal pPoint1 As ESRI.ArcGIS.Geometry.IPoint, ByVal pPoint2 As ESRI.ArcGIS.Geometry.IPoint) As ESRI.ArcGIS.Geometry.ILine
        CreateLine = New ESRI.ArcGIS.Geometry.Line
        CreateLine.PutCoords(pPoint1, pPoint2)
    End Function

IAffineTransformation2D3GEN.DefineFromControlPoints Method

Product Availability

See Also