ras2vox_tkr: The FreeSurfer default ras2vox_tkr matrix.
In neuroconductor/fsbrain: Managing and Visualizing Brain Surface Data

Description Usage Value See Also Examples

Applying this matrix to a FreeSurfer surface RAS coordinate (from a surface file like 'lh.white') will give you the voxel index (CRS) in a conformed FreeSurfer volume. The returned matrix is the inverse of the 'vox2ras_tkr' matrix.

1	ras2vox_tkr()

numeric 4x4 matrix, the FreeSurfer ras2vox_tkr matrix.

Other surface and volume coordinates: vox2ras_tkr()

   # Compute the FreeSurfer CRS voxel index of surface RAS coordinate (0.0, 0.0, 0.0):
   ras2vox_tkr() %*% c(0, 0, 0, 1);
   # Show that the voxel at surface RAS corrds (0.0, 0.0, 0.0) is the one with CRS (128, 128, 128):
   ras2vox_tkr() %*% c(0.0, 0.0, 0.0, 1);