R: Build an affine matrix up from its constituent...

buildAffine {RNiftyReg} | R Documentation

## Build an affine matrix up from its constituent transformations

### Description

This function does the opposite to `decomposeAffine`, building up an affine matrix from its components. It can be useful for testing, or for rescaling images.

### Usage

    buildAffine(translation = c(0, 0, 0), scales = c(1, 1, 1),
      skews = c(0, 0, 0), angles = c(0, 0, 0), source = NULL,
      target = NULL, anchor = c("none", "origin", "centre", "center"))

### Arguments

`translation` | Translations along each axis, in `pixunits` units. May also be a list, such as that produced by `decomposeAffine`, with elements for translation, scales, skews and angles.
`scales` | Scale factors along each axis.
`skews` | Skews in the XY, XZ and YZ planes.
`angles` | Roll, pitch and yaw rotation angles, in radians. If `source` is two-dimensional, a single angle will be interpreted as being in the plane as expected.
`source` | The source image for the transformation (required).
`target` | The target image for the transformation. If `NULL` (the default), it will be equal to `source`, or a rescaled version of it if any of the `scales` are not 1. In the latter case the scales will be reset back to 1 to produce the right effect.
`anchor` | The fixed point for the transformation. Setting this parameter to a value other than `"none"` will override the `translation` parameter, with the final translation set to ensure that the requested point remains in the same place after transformation.

### Value

A 4x4 affine matrix representing the composite transformation. Note that NiftyReg affines logically transform backwards, from target to source space, so the matrix may be the inverse of what is expected.

### Author(s)

Jon Clayden <code@clayden.org>

### See Also

`decomposeAffine`, `isAffine`

[Package RNiftyReg version 2.6.5 Index]