Investigate smoothing migration

[dzenanz]

Red intersection is original mesh, colored intersection is the smoothed mesh. There is some visible shrinking which is expected, and twice as big translation to the screen left (patient right). There is no translation in S/I or A/P direction.

Possible solutions

• Transfer splitting IDs to original mesh (results can be a bit more noisy as the old distances are computed on post-smoothing models)
• Use non-shrinking version of the smoothing filter: vtkWindowedSincPolyDataFilter (a bit slower)

For @yehan0223.