Hi Michael,

no, XSI does it correctly IMO.

Since I need to use the "user defined normals" from MoI in XSI, it uses those very strictly.
Normal normals can be flipped easily in XSI, but not user normals AFAIK - which makes kind of sense.

There is a plugin to edit user normals for XSI, which includes the inversion of the normal direction, but it is rather old and I couldn't get it to work on the already existing normals from MOI. (Anybody knows how to make that possible? The docs are no longer available for that tool in Netview)

For normal objects this wouldn't be much of a problem - as you said it would be possible to just use doublesided materials. But in this case I am doing glass/water renderings for bottle-designs and the surface normal has to point in the right direction for the Inside/Outside based glass refraction and reflection calculations to work correctly.

I will try closing the surface completely and see if that helps. That sounds like it could work (the bottles are open on the top where the cap covers them).

EDIT: Closing the bottles at the top worked! Thank you so much for the fast help!

EDIT2: I spoke too early. It seems that of 3 bottles in the scene, 2 are correct and one is wrong - and which one seems to be random...

I think this is a very important thing to have inside of MoI though - not only on export.

Thank you very much!

Thomas