Hi Jan,

If possible, use .niml.dset datasets for surface data.
AFNI programs should work pretty well with them. I would
suggest GIFTI, but I don't think 3dVol2Surf can output
that yet (I don't remember).

Using 1D datasets with 3dcalc is actually a somewhat
specialized operation (which is why 1deval exists).

You might be able to copy your datasets to .niml.dset:

3dcopy bs_lh_r1_vr_surf-test_mean.1D bs_lh_r1_vr_surf-test_mean.niml.dset

I'm not sure about the 1D.dset version though, that may
be somewhat specific to SUMA (I'm not positive, you can
try 3dcopy with that, too).

If 3dcopy fails, use the more specific ConvertDset SUMA
program (and output using niml_asc, or niml_bi). You
could even try out the most modern GIFTI format, using
extension .gii. That is the surface form of NIfTI, say.

Just note that when you want the output to have a specific
format (.niml.dset or .gii, say), you need to include that
extension in the output name (e.g. -prefix new_dset.gii).

- rick