One series of transformations that can be useful is to get trackvis trk tractography data into the same space as freesurfer surfaces (e.g. smoothwm, pial). In order to do this, the following steps must be taken:

1. Load vertices from a ''trk'' file and put them in CRS (Column, Row, Slice) of the B0 volume

The first step is to load the trk data from a file. The file format is described in detail at the following link.

2. Transform the ''trk'' vertices from CRS -> tkReg (also called "Surface RAS" or "tkRAS")

3. Load vertices for a surface (e.g., lh.smoothwm)

4. Apply tkRAS-to-tkRAS registration matrix to surface vertices

orig.mgz volume must first be registered with the B0 volume produced by the diffusion toolkit (e.g., dti_b0.nii')

This page describes how to transform coordinate from TrackVis