[Freesurfer] How to convert a cortical thickness map to a NIFTY file

Hi,

I have a question regarding how to convert a cortical thickness map (i.e. lh.thickness) to a NIFTY file.

I have a subject called 'subjid' and I run recon-all on it. So I got the ?h.thickness files. Does freesurfer provide a tool to convert the surface file to a nifty file?

I tried using the command 'mri_surf2vol' as follows: mri_surf2vol --surfval lh.thickness --hemi lh --template orig.mgz --volregidentity subjid \ --outvol /path/to/lh.thickness.nii

The thickness values of the output lh.thickness.nii are integers between 1 and 3. But the original thickness values are between 0~5 and not all of them are integers.

Could someone know what's wrong or suggest another tool?

Thanks in advance.

Best,

Xiaojing