Hi Pilou,

> Normals can be also remove in the good way before the rendering in C4D
> but in this case informations of the "Normal Smoothing" based on the Nurbs
> objects is lost :(

But why are the normals lost in C4D upon the flip?

This sounds to me like a bug in C4D - it should not lose the "good vertex normals" when you do a flip, it should just reverse those accurate normals and keep them around instead of throwing them away.

- Michael