isAffine returns a logical value indicating whether its argument is,
or resembles, a 4x4 affine matrix. asAffine converts a suitable
matrix to the affine class, attaching the source and target images as
attributes. Affine transformations are a class of linear transformations
which preserve points, straight lines and planes, and may consist of a
combination of rotation, translation, scale and skew operations.
isAffine(object, strict = FALSE)asAffine(object, source = NULL, target = NULL)
# S3 method for affine
print(x, ...)
A logical value, which is TRUE if object appears to be
an affine matrix.
An R object.
If TRUE, this function just tests whether the object is
of class "affine". Otherwise it also tests for an affine-like 4x4
matrix.
Source and target images for the transformation.
An "affine" object.
Additional parameters to methods. Currently unused.
Jon Clayden <code@clayden.org>
NiftyReg's convention is for affine matrices to transform world coordinates
(in the sense of voxelToWorld) from TARGET to SOURCE space, although
transforms are logically applied the other way.