IAffineTransformation2D2 Interface

Provides access to members that define and manipulate affine transformations.

Members

	Name	Description
	DefineFromControlPoints	Defines the best affine transformation between two sets of points. Can be used to register paper maps on a digitizer.
	DefineFromControlPointsEx	Defines the best affine transformation between two sets of points. Can be used to register paper maps on a digitizer.
	DefineFromEnvelopes	Defines a transformation that maps a point relative to one envelope to a similar position relative to another envelope.
	DefineFromEnvelopesEx	Defines a transformation that maps a point relative to one envelope to a similar position relative to another envelope.
	DefineReflection	Defines a transformation that can perform a reflection about the line l.
	GetControlPointError	Returns the errors involved in moving control point i from the 'from' to 'to' system. These error terms are valid after using DefineFromControlPoints/Ex to define the transformation.
	GetRMSError	RMS (Root Mean Square) error expressed relative to the 'from' and 'to' points defining the transformation. These error terms are valid after using DefineFromControlPoints/Ex to define the transformation.
	IsReflective	Indicates if the transformation contains a reflection (determinant is negative).
	Move	Incorporates a translation factor into the transformation.
	MoveOrigin	The origin of accumulated transformations used when projecting an affine transformation to a different spatial reference system.
	MoveOrigin	The origin of accumulated transformations used when projecting an affine transformation to a different spatial reference system.
	MoveVector	Performs an X and Y translation defined by a 2D vector.
	PostMultiply	Post-multiplies the transformation by another transformation.
	PreMultiply	Pre-multiplies the transformation by another transformation.
	Project	Moves this transformation into another spatial reference. If the transformations contains only translations, then use the MoveOrigin property to define an equivalent translation in the new spatial reference.
	Reset	Resets the tranformation.
	Rotate	Incorporates a rotation (in radians) into the transformation.
	Rotation	The rotation angle. Will not be able if different x/y scale factors have been incorporated into the transformation.
	Scale	Incorporates scale factors into the transformation.
	SpatialReference	The spatial reference in which this transformation is meaningful.
	TransformMeasuresFF	Transforms floating point measures to floating point measures (or do the inverse).
	TransformMeasuresFI	Transforms floating point measures to integer measures (or do the inverse).
	TransformMeasuresIF	Transforms integer measures to floating point measures (or do the inverse).
	TransformMeasuresII	Transforms integer measures to integer measures (or do the inverse).
	TransformPointsFF	Transforms floating point points to floating point points (or do the inverse).
	TransformPointsFI	Transforms floating point points to integer points (or do the inverse).
	TransformPointsIF	Transforms integer points to floating point points (or do the inverse).
	TransformPointsII	Transforms integer points to integer points (or do the inverse).
	XScale	The scale along the X axis.
	XTranslation	The translation along the X axis.
	YScale	The scale along the Y axis.
	YTranslation	The translation along the Y axis.

IAffineTransformation2D2.MoveOrigin Property

The origin of accumulated transformations used when projecting an affine transformation to a different spatial reference system.

Public ReadOnly Property MoveOrigin_2 As IPoint

public IPoint MoveOrigin_2 {get;}

Remarks

Projecting a distance from one spatial reference to another is meaningless without specifying where the distance is measured. A line that is one unit in length in one spatial reference can map to a varying number of units on another spatial reference depending upon the location of the end points. For this reason, when your AffineTransformation2D has a translation (i.e., a Move), it is important to specify a point as the Origin for this move. This is done using the MoveOrigin property.

When the AffineTransformation2D you are projecting has a rotation, specifying a MoveOrigin is not necessary as the origin (or center) of the rotation is considered to be the origin of any translations as well.

Using a MoveOrigin that is closest to the geometry that you are projecting results in a more accurate transformation. In the following illustration, a point P1 is transformed by an AffineTransformation2D to the point P2. Both P1 and the Affine Transformation have the same spatial reference. P2 when projected to another spatial reference results in PP2.

If you project P1 and the Affine Transformation into PP2's spatial reference, and transform the projected point PP1 using the projected transformation, you will get the point PP2 provided you set the MoveOrigin of the AffineTransformation to P1 before projecting it. The results of this transformation will be more accurate when the MoveOrigin is closer to P1.

For the code illustrating this, see the example for this topic.

AffineTransformation2D Example

For an AffineTransformation2D to be projected, its MoveOrigin should be set so that it is within the horizons of the new projection.