[Freesurfer] Surface segmentation for resting state

Dear free surfer experts,

I am conducting a resting state fMRI study using a lagged analysis method. To do this method on a volume, I have used 6 mm cubes as rois covering the whole brain but masked for grey matter. I use these values in a correlation map.

I would like to do a similar approach here. Is there a way to get measurements ~6mm apart averaging the vertices 3 mm away. basically, I would like to parcel the cortex surface map into 6mm rois evenly distributed over the surface of the cortex. I would like to take advantage of the fact that I can take measurements along surfaces and not across sulci.

Is there an automated way or easy way of building this ROI map.

Erik Jahner