Hi Bruce,
I see, the ?h.sphere.reg files are a surf file and the coordinates specify a sphere (surprise, surprise). I assume these are coordinates given after the spherical morph into the target brain space (eg, average7). My interest is in locating a cortical vertex for subject A and then finding all the spherically coregistered vertices for other subjects. To find coregistered vertices across subjects, I assume a 3D distance metric for the ?h.surf.reg data would work. That is,
a) select vertex V from subject A b) extract the spherical coordinates from ?h.sphere.reg for V c) find the nearest vertex in the ?h.sphere.reg file for subject B, using a linear 3D Euclidian distance metric
Will that give the result of the cortical spherical coregistration across subjects (after spherical morphing to the template brain)?
Thanks, Darren