RNifti: voxelToWorld – R documentation

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voxelToWorld

Transform points between voxel and “world” coordinates

Description

These functions are used to transform points from dimensionless pixel or voxel coordinates to “real-world” coordinates, typically in millimetres, and back. Actual pixel units can be obtained using the pixunits function. The origin function gives the voxel coordinates of the real-world origin.

Usage

voxelToWorld(points, image, simple = FALSE, ...)

worldToVoxel(points, image, simple = FALSE, ...)

origin(image, ...)

Arguments

`points`	A vector giving the coordinates of a point, or a matrix with one point per row.
`image`	The image in whose space the points are given, or a 4x4 numeric xform matrix.
`simple`	A logical value: if `TRUE` then the transformation is performed simply by rescaling the points according to the voxel dimensions recorded in the `image`. Otherwise the full xform matrix is used.
`...`	Additional arguments to `xform`.

Value

A vector or matrix of transformed points.

Note

Voxel coordinates are assumed by these functions to use R's indexing convention, beginning from 1.

Author(s)

Jon Clayden <code@clayden.org>

Examples

im <- readNifti(system.file("extdata", "example.nii.gz", package="RNifti"))

# Find the origin
origin(im)

RNifti

Fast R and C++ Access to NIfTI Images

v1.3.0

GPL-2

Authors

Jon Clayden [cre, aut] (<https://orcid.org/0000-0002-6608-0619>), Bob Cox [aut], Mark Jenkinson [aut], Matt Hall [ctb], Rick Reynolds [ctb], Kate Fissell [ctb], Jean-loup Gailly [cph], Mark Adler [cph]

Initial release

2020-12-04