vec2dtransf (version 1.1.3)

AffineTransformation-class: Class "AffineTransformation"

Description

Class to define affine transformations to be applied on sp objects. Affine transformations can rotate, shift, scale (even applying different factors on each axis) and skew geometries.

Objects from the Class

Objects can be created by calls to the function AffineTransformation.

Slots

controlPoints:

Object of class "data.frame" containing control point coordinates arranged in four (4) columns: X source, Y source, X target, Y target.

parameters:

Object of class "numeric". A vector of six (6) parameters for representing the transformation, namely: a, b, c, d, e and f, where
x' = ax + by + c
y' = dx + ey + f

residuals:

Object of class "matrix". Only set if Least Squares is applied, i.e., if more than three (3) control points were provided. Residuals are the difference between transformed source coordinates and target coordinates of control points.

rmse:

Object of class "numericOrNULL". Only set if Least Squares is applied, i.e., if more than three (3) control points were provided. Root Mean Square Error, useful when comparing two transformations. It measures the general deviation of transformed source coordinates with respect to target coordinates of control points. It has the same units as the coordinates, usually meters.

Extends

Class "Cartesian2DCoordinateTransformation", directly.

Methods

calculateParameters

signature(object = "AffineTransformation"):
Calculate transformation parameters from control points.

Author

German Carrillo

References

Iliffe, J. and Lott, R. Datums and map projections: For remote sensing, GIS and surveying. Section 4.5.4. pp.115-117, 2008.

See Also

AffineTransformation

Examples

showClass("AffineTransformation")