Hello again.
I reasoned that the likely reason for the mismatch between the digitized nasion and the default anatomy nasion is simply that they come from two different heads with a different proportion between the distance between the preauricular points and the distance between the nasion and the coordinates origin. Does this make sense?
If that is the case, the solution to this could be warping, but it is fundamental that warping incorporates the digitized fiducials as the true fiducials. I tried warping and the result seems to confirm this:
EEG_3D_coreg_warped@default_subject.tif (224.6 KB)
However, I am not completely sure as fiducials were also among the additional head points. Can you please confirm that warping considers as fiducials the digitized ones (i.e. the ones from the 3D scanner image) and not the default anatomy ones? Otherwise, how should I constrain it to do so?
In general, is there any drawback in doing warping on EEG data like this? (I read in this previous thread that warping was originally designed for MEG data: Warping vs. MRI Registration Edit - #2 by Francois).
Thanks!
Marco