Hello,

I define a patch of the occipital lob



and run the comand
 mris_flatten  lh.occip.patch.3d lh.occip.flat.patch.3d

why do I end up with a 'closed' flattened surface 



points around the cutting line stay close and not far away like in classical view
like this one :


What's wrong ?

Thank for your help

Romain