We’ve been discussing this for quite a while and I’m still thinking there’s a difference between the Joint Smoothing exposed by the current Segmentations and the Joint Smoothing originally provided by @Lorensen. As dicussed, @Lorensen’s algorithm maintained watertight boundaries by explicitly moving the corresponding vertices where to models abut such that they have the exact same location in the algorithm output (e.g. two STL files would have exact watertight fit). Last I checked, as in the screenshots linked above, the current implementation can still leave some (small) gaps.
Also @Lorensen’s algorithm should never change the topology, since it works by first building surfaces that exactly follow the voxel edges (a ‘cuberile’ model) and then only smooths by moving the vertex points.