Fresnel, IOR values, and metals/reflections

[spiralof5]

I came from Maya and Blender. Most everything has an IOR value because most everything reflects. There is a nice long list floating around the internet with different IOR values.

The problem is that I am confused as to why Vray doesn't use real values for metals? Why do I have to jack up the IOR to an obscene number to get metallic reflections? Blender makes it simple being the IOR just is what it is and works.

I don't know why but I have a really hard time understanding Vrays setup. If I were to put a falloff on the reflection, it seems as if that would be the more correct way and you just have to find the falloff curve in real life. Yet, when I render the falloff I seem to be getting super harsh starting points instead of a nice blend. The curve editor is just a thin hair up or down for a sweet spot and it seems impossible to hit.

Is there another way?

[Rens]

Hi, there's some more info in this thread:
http://forums.chaosgroup.com/showthr...-falloff/page5

Blender makes it simple being the IOR just is what it is and works.

What do you mean by that? VRay's setup is very straightforward, though it is set up for non-metals only like most renderers (it doesn't have a k value for the IOR).

There are several OSL shaders out there to calculate metal fresnel curves, Vlado has put one up here:
http://docs.chaosgroup.com/display/O...Fresnel+shader

[soulburn3d]

Would be nice if this feature were built into the VRayMtl directly.

- Neil