Not the watershed algorithm because I already had the voxels labeled (scalp, skull, ...) so the surfaces were obtained by marching cubes + Laplacian smoothing + mesh decimation + corrections for topological issues like holes and such
For some subjects, the cortex and inner skull surfaces seem to be intersecting, which might cause problems running OpenMEEG.
Have you computed forward models with OpenMEEG with all the age ranges?