Odd glancing reflection problem

[tricky]

Its been a while since I've come accross this problem. The reflections 'cut off' in an arc across my ceiling. What settings need to be adjusted to correct this?

[instinct]

Reflection Cutoff in the material options i'd guess.

Regards,
Thorsten

[tricky]

Will take a look. I just find it a bit odd that I am getting this effect with such a straightforward scene. I never really touch reflection cutoff values normally. Is this quite a common tweek?

[BBB3]

It seems to be over here. I tend to put it at 0,001 as default these days.

[MoonDoggie]

Yeah, it's the reflection cutoff, it's probably set to .01, change it to .001. That'll fix it. I used to never have to change it until one random day it started defaulting to 0.01. It probably has to do with your 3dsmax decimal precision. *Shrug*

[Deflaminis]

This might be a silly question, but wouldn't lowering the value just move the problem to a different spot?

[MoonDoggie]

Try it with values 0.5, 0.1, 0.01, 0.001 and you'll see. You can preview what it'll do within the material editor as well.

[dlparisi]

@tricky: Did changing the reflection cutoff fix this for you or we're you able to resolve it some other way. I've got a scene now that the is experiencing the same problem and I've tried changing the material cutoff to 0 as well as every light's cutoff to 0 (just trying everything). Very frustrating.

[Dariusz Makowski (Dadal)]

From what I remember u dont want to have 0 - it will generate unlimited sample range that would render for decades... just use 0.001 or so...

[dlparisi]

From what I remember u dont want to have 0 - it will generate unlimited sample range that would render for decades... just use 0.001 or so...

It tried .001 too - no luck.

[Dariusz Makowski (Dadal)]

U sure its issue of cut-off? U try shader & light cut-off?

Maybe there is model bugged, mapping, something casting shadow etc etc? have u try isolating objects ?

[dlparisi]

U sure its issue of cut-off? U try shader & light cut-off?

Maybe there is model bugged, mapping, something casting shadow etc etc? have u try isolating objects ?

If I turn off reflections for the object it goes away. I've replace the object with just a simple plane with the same material and I get the same results (I get the same reflection arc in the same place). I remade the material with a new vraymtl and I get the same results too (it's just a simple material with a vraycolor in the diffuse slot and some Fresnel reflections). Further, if I change the IOR for the material it shifts where that refelction arc happens so I think it's definitely related to a reflection problem.

[Dariusz Makowski (Dadal)]

its very weird... how about ur scale? There has to be some issue somewhere because those cut offs happens only at very extreme camera angels and not on what you have...

[leo.surrealismo]

change the refractive ior value to 3....

[dlparisi]

its very weird... how about ur scale? There has to be some issue somewhere because those cut offs happens only at very extreme camera angels and not on what you have...

Scale is normal feet inches thing (same as I use in hundreds of other setups). I think you're wrong about the extreme angle though. The help file states that for the cutoff "V-Ray tries to estimate the contribution of reflections/refractions to the image, and if it is below this threshold, these effects are not computed." so for a fresnel reflection it's actually the non-extreme angles that get cutoff (when the surface normal is facing the camera). This is what's happening in my scene as well as what's happening in tricky's shot at the start of the thread.

change the refractive ior value to 3....

That would change my reflection though.