Hi Jorge,

the fsaverage subject has less surface area than any of the individuals. We typically correct for this by including the average surface area in the surfaces created by make_average_subject. For example:

mris_info ~/local_subjects/fsaverage/surf/lh.white reading group avg surface area 864 cm^2 from file . . .

cheers, Bruce

On Thu, 13 Sep 2007, jorge luis wrote:

Ok, but my automatic procedure constructed the ROI masks on the lh.sphere (not on lh.sphere.reg)of the fsaverage subject.

Is it wrong to compute the area of a ROI in the fsaverage spherical surface by adding the areas of the triangular faces inside this region? (The area of each triangular face being computed using the spherical coordinates of its vertices and the Heron formula for the triangle area)

Thank you for your useful help Jorge

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