I am trying to render cluster corrected, volumetric 3dttest++ results in surface space using 3dVol2Surf. Normally, I would simply use the afni and suma viewers together to accomplish this, but I need to use 3dVol2Surf since I would like to view multiple overlays in surface space.

For a quick test, I converted output from 3dClusterize (-pref_dat <some_map>) to surface space using 3dVol2Surf. I wanted to see if I could replicate what I would see if I used the normal afni - suma combo (combo A), but using 3dClusterize -> 3dVol2Surf instead (combo B). Both gave quite similar outputs, but combo B gave small numbers of extraneous clusters I did not see in combo A.

I used the following 3dVol2Surf command, using the average map-function, with 10 steps and nodes as f_index:

for hemi in lh rh; do
    3dVol2Surf \
        -spec "suma_TT_N27/TT_N27_${hemi}.spec" \
        -sv "../suma_TT_N27/TT_N27_SurfVol.nii" \
        -grid_parent "${directory}/ispositive_${alphas[$t]}+tlrc" \
        -surf_A ${hemi}.smoothwm \
         -surf_B ${hemi}.pial \
         -map_fun ave \
        -f_step 10 \
        -f_index nodes \
        -out_niml  "${hemi}_clust.niml.dset \
        -overwrite
done

Is there an equivalent 3dVol2Surf command I could use to replicate what I see in combo A (i.e. afni <-> suma talking via niml)?