# compose-dofs¶

## Synopsis¶

compose-dofs <T1> <T2>... <T> [-target <image>]


## Description¶

Computes the composition T of the given input transformations such that

$T(x) = Tn o ... o T2 o T1(x)$

## Command options¶

-target <image>

Target image on which images will be resampled using the composed transformation. The finite grid of the target image is used to determine an appropriate domain on which to approximate the displacement field of the composite transformation when -approximate is given.

-rotation, -norotation

Whether to allow rotation when composite transformation is affine. (default: on)

-translation, -notranslation

Whether to allow translation when composite transformation is affine. (default: on)

-scaling, -noscaling

Whether to allow scaling when composite transformation is affine. (default: on)

-shearing, -noshearing

Whether to allow shearing when composite transformation is affine. (default: on)

-approximate

Approximate the composed transformation using a single FFD. (default: off)

-scale <s1> [s2...]

Scaling factors for each input (SV) FFD in the same order as the positional input file name arguments. These factors can only be applied to single FFDs, and are mainly useful for velocity based transformations. For rigid, similarity, or affine transformations, use -1 to invert the input transformation. (default: 1)

-bch [<n> [yes|no]]

Use Baker-Campbell-Hausdorff (BCH) formula to approximate composition of SV FFDs. All input transformations must be of type cubic B-spline SV FFD. Arguments are optional. The first argument is the number of BCH terms to use. The minimum is 2 terms, i.e., the sum of left and right velocity fields. The second argument is a boolean flag indicating whether or not the Lie brackets should be computed using the Jacobian of the vector fields (yes) or if it should be approximated as the difference of the compositions in either order. (default: 6 yes)

-nobch

Do not use BCH formula to compose SV FFDs. Instead, evaluate composite displacements and approximate these even when all input transformations are of type SV FFD.

## Standard options¶

-v, -verbose [n]

Increase/Set verbosity of output messages. (default: 0)

-debug [level]

Increase/Set debug level for output of intermediate results. (default: 0)

-version [major.minor]

Print version and exit or set version to emulate.

-revision

Print revision (or version) number only and exit.

-h, -help

Print help and exit.