In the documentation of mris_thickness_diff it says "This program computes the difference of two surface data sets defined on the two surface mesh. Result = data2 - data1 (in sense of closest vertex)." Also, on the thickness repeatability page, it states that the output of mris_thickness_diff is sampled on the first surface.
Just want to make sure I'm understanding this correctly: this means that mris_thickness_diff does NOT resample the data onto a common mesh to do vertex-wise subtraction, but rather, for each vertex in surface1, it finds the spatially closest vertex in surface2 and then subtracts the data2 at that point from data1 at the original point.
So I assume this means that using mris_thickness_diff, even if you have two thickness data files which are sampled on the *same* mesh, if they are physically not aligned in space for whatever reason, you will get very wrong results? (I think I had this problem earlier and didn't understand what was going on.)
One more question about the thickness repeatability page. How will the results obtained in this way differ from results obtained by aligning the surfaces with mri_surf2surf and simply doing a vertex- wise subtraction using matlab?
-- -dave---------------------------------------------------------------- Science arose from poetry... when times change the two can meet again on a higher level as friends. -Göthe