Hi Michael

the ascii file is first:

vertex_nx vertex_ny vertex_nz ripflag (usually 0) . . . up to # of vertices. Then, for each face: vertex_0 vertex_1 vertex_2 ripflag

cheers Bruce On Thu, 2 Jun 2011, Michael Waskom wrote:

Hi Bruce et al.

I have a quick question about the interpretation of surface normal files and the various ways you can create them with Freesurfer.

As far as I know, there are two ways to get the normals information:

mris_convert -n lh.inflated lh.inflated.normals2

and

mri_surf2surf --s fsaverage --hemi lh --sval-nxyz inflated --tval lh.inflated.normals2.mgz

The first writes an ascii file with 491522 rows and 4 columns (the last of which is all 0's), while the second writes a surface scalar "image" with dimensions 163842 x 1 x 1 x 3.

Am I right to assume that the coordinates in the mgz image and the first n_vtx rows of coordinates in the ascii file correspond to the surface normals at the vertices of the mesh? And, furthermore, do the remaining coordinates in the ascii file correspond to the surface normals of the triangle faces on the mesh?

Thanks!

Michael _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer