VTK extrusion normal has self intersection cells


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Basically, I have this kind of surface. What I want to do is to add a thickness to it. What I use is extrusion with the normal direction, which looks perfect from outside with two issue:

  1. Self intersection cells inside (because I need to use boolean operations on it later)
  2. Some of extra extrusion is not desired. Basically, I only want more thickness towards the outside not inside