Thanks a lot for your solution, Aimsgraphmesh works very well.
But now, I need to smooth my 3D reconstruction (.mesh) in order to give a smarter appearance to my results.
You can use AimsMeshSmoothing on the .mesh file(s) located in the <roiname>.data directory to smooth them. I had done a little front-end for this in BrainVisa but as it re-wrote input meshes it was a bit dangerous so my colleagues decided to disable it (it is in userLevel more-than-expert).
Denis