[Freesurfer] Geodesic distance across hemispheres

Dear freesurfer people,

I haven’t noticed that computing geodesic distance between two points across hemispheres is not a trivial as I thought.

There are many implementations of Dijkstra algorithm publicly available to compute geodesic distance on a triangular mesh, but it’s a bit tricky to deal with the separated hemispheres. An easy solution could be connecting two meshes: for each medial wall vertex, find a closest (in Euclidian distance) vertex on the medial wall of the other hemisphere, and add a new edge. This would change mesh topology, but it’d be still fine for computing geodesic distance, wouldn’t it?

I wish to learn how other people deals with this problem.

Best regards,