RNiftyReg (version 0.4.1)

decomposeAffine: Decompose an affine matrix into its constituent transformations

Description

An affine matrix is composed of translation, scale, skew and rotation transformations. This function extracts these components.

Usage

decomposeAffine(affine, source = NULL, target = NULL, type = NULL)

Arguments

affine

A 4x4 matrix representing an affine transformation matrix.

source

A "nifti" object representing the source image for the transformation. Only required if type (or the matrix's affineType attribute) is "niftyreg", in which case it is passed to

target

A "nifti" object representing the target image for the transformation. Only required if type (or the matrix's affineType attribute) is "niftyreg", in which case it is passed to

type

The storage convention type of the affine matrix, if it is not stored in the affineType attribute of the matrix.

Value

• A list with components
• scaleMatrix
  A 3x3 matrix representing only the scale operation embodied in the full affine transformation.
• skewMatrix
  A 3x3 matrix representing only the skew operation embodied in the full affine transformation.
• rotationMatrix
  A 3x3 matrix representing only the rotation operation embodied in the full affine transformation.
• translation
  A length-3 named numeric vector representing the translations (generally in mm) in each of the X, Y and Z directions.
• scales
  A length-3 named numeric vector representing the scale factors in each of the X, Y and Z directions. Scale factors of 1 represent no effect.
• skews
  A length-3 named numeric vector representing the skews in each of the XY, XZ and YZ planes.
• angles
  A length-3 named numeric vector representing the rotation angles (in radians) about each of the X, Y and Z directions; i.e. roll, pitch and yaw.

See Also

convertAffine, niftyreg