[Freesurfer] mris_preproc thickness vs functional data

Hello All,

I have a question regarding the actual command issued under the mris_preproc wrapper.

I noticed that when I ran the recon-all -qcache to resample the different anatomical measures like thickness etc to fsaverage, one of the step is the following -

mri_surf2surf --srcsubject 068 --srchemi rh --srcsurfreg sphere.reg --trgsubject fsaverage --trghemi rh --trgsurfreg sphere.reg --tval 068.1.mgh --sval ./lh.thickness --sfmt curv --noreshape --no-cortex

When I ran mris_preproc using the tutorial as specified here http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/MultiModalFmriGroup

the step similar to the one above is the following mri_surf2surf --srcsubject 068 --srchemi rh --srcsurfreg sphere.reg --trgsubject fsaverage --trghemi rh --trgsurfreg sphere.reg --tval 068.1.mgh --sval ./rh.VisStimBoth_rb.mgh --noreshape --no-cortex"

What does the "--sfmt curv" do ?

What happens if its included in the resampling of the functional data ? Should I ?

Please let me know.

Thanks

Ri