Vray Fresnel Issue - Sudden Reflection Dropoff

[braddewald]

The problem is very basic. When I set up a pure black material with fresnel reflections, I get a sudden "dropoff" of reflections when I'm using a low reflection value at some point along the curved object (the sample slot sphere in this case). Refl. Glossiness has no impact on the sudden "dropoff". I'm using a completely standard setup along with linear workflow.

 

Any idea what this is?

 

[Corey Beaulieu]

I've had this same issue. I've figured out that if you reduce a ref value below 48 this happens. In a way it makes sense in that objects that have lower reflection values tend to have lower IOR values, but as a default I just leave it 1.6 and stay at a min. of 50 for my ref color. Use the glossiness to get rid of any additional unwanted reflections.

 

I don't have max open right now, but I believe that I have also resolved this with a falloff map. I could be mistaken though.

[braddewald]

I tried replacing the fresnel checkbox with a falloff map set to fresnel in the reflection slot but it just looked identical (same problem). It just seems like I should be able to use a refl. value below 50. Is Chaos Group aware of the issue?

[Stephen Thomas]

Drop the cutoff value down to 0.001, it's under options.

[braddewald]

That worked! Thanks so much!!

[Stephen Thomas]

No problem I think the default value keeps render times lower in general, but in certain cases it needs to be lowered.