spatstat.geom (version 3.2-9)

affine.owin: Apply Affine Transformation To Window

Description

Applies any affine transformation of the plane (linear transformation plus vector shift) to a window.

Usage

# S3 method for owin
affine(X, mat=diag(c(1,1)), vec=c(0,0), ..., rescue=TRUE)

Value

Another window (of class "owin") representing the result of applying the affine transformation.

Arguments

X

Window (object of class "owin").

mat

Matrix representing a linear transformation.

vec

Vector of length 2 representing a translation.

rescue

Logical. If TRUE, the transformed window will be processed by rescue.rectangle.

...

Optional arguments passed to as.mask controlling the pixel resolution of the transformed window, if X is a binary pixel mask.

Author

Adrian Baddeley

and Rolf Turner

Details

The window is subjected first to the linear transformation represented by mat (multiplying on the left by mat), and then the result is translated by the vector vec.

The argument mat must be a nonsingular \(2 \times 2\) matrix.

This is a method for the generic function affine.

See Also

affine, affine.ppp, affine.psp, affine.im, rotate, shift

Examples

  # shear transformation
  shear <- matrix(c(1,0,0.6,1),ncol=2)
  X <- affine(owin(), shear)
  if(interactive()) plot(X)
  affine(letterR, shear, c(0, 0.5))
  affine(as.mask(letterR), shear, c(0, 0.5))