Hi,
I'm trying to figure out how to go from a coordinate in mni305 space to a vertex index in fsaverage. In the README file that comes with fsaverage it's stated that surface coordinates are in talairach space, so they align with the MNI305 volume (and the talairach.xfm is the identity). But when I select a vertex in fsaverage (using tksurfer) I have three different coordinates. For example, vertex 62176 gives
1. the actual 3d coordinate of the vertex in the mesh -2.4876, -5.1338, 10.0494 2. the RAS coordinate -1.97, -4.48, 10.51 3. the Talairach coordinate (which I suppose are in fact MNI305 coordinates..) -1.95, -3.85, 9.87
this doesn't seem to be just a translation because when I compare actual 3d and talairach, the difference between the x coord (for example) of different vertices is not the same...
how does tksurfer convert to talairach coordinates?
thanks in advance!
roberto