Hi,
I'm trying to understand the conversion from RAS (freesurfer surface coordinate) to volume space (x, y, and z.. According to Graham Wideman documentation here http://www.grahamwideman.com/gw/brain/fs/coords/fscoords.htm (if it is not outdated), Right is negative x, *Anterior is positive z*, and *Superior is positive y*.
Just to double check, usign mri_info on a sample T1.mgz in one subject I get this ras to voxel transform:
-1 0 0 126.944 0 0 -1 135.16 0 1 0 110.6 0 0 0 1
Assuming we have correctly set the (0, 0, 0), and we can extract R A and S (respectively) coordinates using C++ or Python code it means: Right is negative x, *Anterior is negative z*, and *Superior is positive y* (conflicting coordinates are in vold). Am I missing anything here, or coordinate systems have changed from the probably outdated documentation? Thanks in advance for any input on this rather confusing point.
All the best, Arman