ArcObjects Library Reference (Geometry)

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(
  Array* fromPoints,
  Array* toPoints
);

[C++]

Parameters
fromPoints [in]
  fromPoints is a parameter of type Array
toPoints [in]
  toPoints is a parameter of type Array

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

.NET Related Topics

How to perform an affine transformation

IAffineTransformation2D3GEN.DefineFromControlPoints Method

Product Availability

See Also

.NET Related Topics