Dear Greve
      Thank you for your reply
        I want to use surf2vol to get volume files of gray thickness.And
the --volreg Contains the matrix that maps XYZ in the reference anatomical
to XYZ in the functional volume. So I use bbregister.Why I need not  invert
the BBR registration matrix with surf2vol?I mean , the BBR registration
matrix is  functional to anatomial volume,the surf2vol need anatomical to
XYZ And I use bbregister --s sub1 --mov /sub1/mri/orig.nii --init-fsl
--reg/sub1/register.dat
--t1;mri_surf2vol --surfval /sub1/surf/lh.thickness.fwhm0.fsaverage.mgh
--hemi lh --surf pialfs --volreg /sub1/register.dat --outvol ./ --template
/sub1/mri/orig.nii
the resluts are 256 volumes.Why this happen?Should the voulme  be 1 file?