param2xfm

create a MNI transform file from rotation, translation, scale, and shear parameters

param2xfm [options] <result.xfm>

DESCRIPTION

param2xfm creates a MNI .xfm linear transform file from user-specified transformation parameters. The user can specify translations, rotations (in degrees), scaling factors, shears, and the center of rotation/scaling.

The resulting transform is constructed by composing the individual transformations (translation, rotation about center, scaling about center, and shearing) into a single 4x4 affine transformation matrix, which is written out in MNI .xfm format.

This is the inverse operation of xfm2param, which extracts parameters from an existing transform file.

OPTIONS

-center x y z

Set the center of rotation and scaling. Default: 0 0 0.

-translation x y z

Set the translation in millimetres along the X, Y, and Z axes. Default: 0 0 0.

-rotations rx ry rz

Set the rotation angles in degrees about the X, Y, and Z axes. Default: 0 0 0.

-scales sx sy sz

Set the scaling factors along the X, Y, and Z axes. Default: 1 1 1.

-shears shx shy shz

Set the shear parameters along the X, Y, and Z axes. Default: 0 0 0.

-clobber

Overwrite the output file if it already exists.

-help

Print summary of command-line options and exit.

-version

Print the program’s version number and exit.

EXAMPLES

Create an identity transform:

param2xfm identity.xfm

Create a transform with a 5mm translation along X:

param2xfm -translation 5 0 0 shift.xfm

Create a transform with 10-degree rotation about the Z axis:

param2xfm -rotations 0 0 10 rotate.xfm

Create a transform that scales by 1.1 in all dimensions around a specified center:

param2xfm -scales 1.1 1.1 1.1 -center 0 0 0 scale.xfm

AUTHOR

Louis Collins - McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University.

COPYRIGHTS

Copyright © 1993 by Louis Collins

SEE ALSO

xfm2param xfmconcat xfminvert minctracc