Head surfaces are in
bem/inner_skull.surf
Indeed, sorry I skipped that. You can load these surfaces directly with a right-click > Import surface > Select FreeSurfer and answer "NO" to the question about applying an additional transformation.
The corresponding script call, to be added immediately after import_anatomy_fs, it will also make them as default head/skull surfaces:
% Import head surface
BemFiles = {...
bst_fullfile(FsDir, 'bem', 'inner_skull.surf'), ...
bst_fullfile(FsDir, 'bem', 'outer_skull.surf'), ...
bst_fullfile(FsDir, 'bem', 'outer_skin.surf')};
[iNewSurfaces, BstBemFiles] = import_surfaces(iSubject, BemFiles, 'FS', 0);
The inner and outer skull surfaces from the bem folder look good, but the head (outer_skin) is too large (ANTS1-0Months3T):
Comparison between Brainstorm head surface (small one) and the outer_skin from the bem folder:
Is this an error from the MNE watershed algorithm?
Or a copy-paste issue between different subjects?
The fiducials contains the standard BS brain fiducial points.
How were they estimated?
These ones need to be in Brainstorm MRI coordinates (the first line of coordinates in the Brainstorm MRI viewer).
co-author currently working with these just let me know that "The montages claim to be in the head coordinate frame rather than the MRI coordinate frame"
The coregistration in Brainstorm is independent from the original coordinate system of either the surfaces or the electrodes. Everything is converted to CTF/SCS coordinate system using the NAS/LPA/RPA, so as long as these points are correctly defined wrt the other files, there is no possible coordinate system issue.