[Freesurfer] Surface area measurement method

Hello FreeSurfers,

after reading this [1] paper about measuring surface area, i realized i don't know what the default way of measuring surface area is in FreeSurfer. Is it similar to what's described in the paper? Could you point me to the right documentation or publication? Forgive me if i've overlooked it, i found something for thickness, but not for area. To clarify, i don't mean parcellation-based areas, i mean the measure that i find in /surf/hemi.area.

thanks, regards, Andreas

[1] Measuring and comparing brain cortical surface area and other areal quantities. Winkler AM, Sabuncu MR, Yeo BT, Fischl B, Greve DN, Kochunov P, Nichols TE, Blangero J, Glahn DC (2012). Neuroimage 61(4):1428-43