
How the cortical thickness measurement works

[from the code]

   foreach vertex
     pick pial surface vertex
     find distance to same-numbered vertex in white matter surface
     find *neighbors* of same-numbered white matter vertex
     check distance from pial surface vertex to them, too
     find minumum distance of all these pairs

   foreach vertex -> same search inverted
     pick same-number white matter surface vertex
     search neighbors on pial (both surfs same topo, don't re-find neighbors)

   average results of two above

Note that this doesn't refer to the normal, which is only
used to calculate a dot product to determine it it is pointing
in or out.

cheers,
marty

