Hi yannada - MoI uses the Solids++ geometry library. This is not the same one used by Alias or Rhino.

All of these engines are based off of the same basic type of NURBS math though, so I wouldn't say any particular one is any more globally "accurate" than any other. They can all contain accurate shapes in them.

Each engine tends to have strengths in the calculation of different particular areas though - one of Solids++ strengths is in boolean operations.

- Michael