A volume axis describes the voxel grid that the volume brain models of a
CIFTI-2 file refer to: its dimensions and the 4x4 transformation matrix that maps the
(0-based) IJK voxel indices to coordinates. The matrix is stored row by row in the
file, and the coordinates it produces are in units of 10^meter_exponent (which is
-3, i.e. millimeters, for the files that Connectome Workbench writes).
cifti.volume(dimensions, transformation_matrix, meter_exponent = -3L)a named list with the entries 'dimensions', 'meter_exponent' and
'transformation_matrix', to be passed to cifti.axis.brain.models or
cifti.axis.parcels.
integer vector of length 3, the dimensions of the voxel grid.
4x4 numeric matrix, the transformation from (0-based)
voxel indices to coordinates. There is no default: a CIFTI-2 file does not store the
voxel size or the position of a volume anywhere else, so a wrong or invented matrix
silently puts the voxels of a structure in the wrong place. Pass the matrix that the
template file has (see cifti.axis.from.template) if you do not know it.
integer, the exponent of the unit of the coordinates.
Other cifti functions:
cifti.axis.brain.models(),
cifti.axis.from.template(),
cifti.axis.labels(),
cifti.axis.parcels(),
cifti.axis.parcels.from.annot(),
cifti.axis.scalars(),
cifti.axis.series(),
cifti.brain.model.surface(),
cifti.brain.model.volume(),
cifti.dim.labels(),
cifti.file.type.for.axes(),
cifti.grayordinates(),
cifti.header.from.axes(),
cifti.label.table(),
cifti.parcel(),
cifti.parcels(),
cifti.series.info(),
cifti.structure.data(),
cifti.structures(),
print.fs.cifti(),
print.fs.cifti.data(),
print.fs.connectome(),
read.cifti(),
read.cifti.header(),
read.cifti.rows(),
read.fs.connectome.cifti(),
write.cifti(),
write.fs.connectome.cifti(),
write.fs.morph.cifti(),
write.fs.parcellated.cifti(),
write.fs.parcellation.cifti(),
write.fs.series.cifti()
volume <- cifti.volume(c(4L, 4L, 4L), diag(c(2, 2, 2, 1)))
volume$dimensions
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