Normal vector to a tissue surface

[gc00]

Hello! I'm interested in the normal component of the Electric field to the grey matter surface. How can I extract the inner normal vector to the cortical surface?

[halder]

to extract the inner normal vector to the cortical surface

1. mask the field (set NaN outside GM) using the Mask Filter available under "Field Data Tools" in the top ribbion.
2. add the Grey Matter Surface in the post-pro
3. interpolate the (masked) field to the grey matter surface using the "Interpolator" which is active when the masked field and surface is selected.
4. get the normal component via the NormalFieldEvaluator under the "Field Data Tools"