Reflection cutoff/clamp?

[fAEkE]

I have seen this problem before, and I have probably posted some question about a couple of years ago, but I don't remember the answer. And the problem does not happen for me very often since I usually use higher refl values. Anyway, here goes:

Take a look at the image. You can see all settings, refl spheres in a white environment. Reflection cuts off if I use to low RGB values. The RGB values also seems to correlate with IOR. If I use higher IOR, I need to lower the RGB value to cut the relf again. Can anyone explain this?

[instinct]

You need to turn up the cutoff parmeter in the material's options

[fAEkE]

You mean that I should turn it down? That worked anyway, thanks! But why have a cutoff paremeter?

[instinct]

To save rendertime. It reduces the amount of reflection rays having to be traced. The initial default was selected so that it would not be noticable in most scenes. Things have changed since then, and if you are using LWF some of these color/brightness based defaults need some tweaking.

Regards,
Thorsten

[fAEkE]

That makes sense, thanks again!