io.orientation: Determine the orientation of an affine's input axes.

In freesurferformats: Read and Write 'FreeSurfer' Neuroimaging File Formats

Determine the orientation of an affine's input axes.

Description

For each of the 3 input (voxel) axes, determines which output (world) axis it corresponds to and whether it is flipped. This is the simplified equivalent of nibabel.orientations.io_orientation(): the dominant output axis of every input axis is used, with output axes removed from consideration once they have been assigned. nibabel additionally applies a polar decomposition first, which only matters for affines that contain shear.

Usage

io.orientation(affine)

Arguments

affine

4x4 numeric matrix.

Value

numeric matrix with 3 rows and 2 columns, as returned by io.orientation. Row i holds the 0-based output axis index and the direction (+1 or -1) of input axis i.

freesurferformats documentation built on Sept. 25, 2026, 1:07 a.m.