I am wondering about how the pial and white surfaces are supposed to match up with the aseg file. I was expecting that when I created a new surface, usinfg mri_surf2surf, halfway between the pial and white surfaces (which I call the cortical ribbon), it would run right down the center of the GM. After creating that surface I converted it to voxel representation with mri_surf2vol. I found that it doesn't match everywhere.
Are the pial and white surfaces not based on the aseg segmentation of G&WM? If they are, why the discrepancy?
Thanks,
-Jeff