Help on glass material

[888.marc]

I'm working on a bathroom rendering, and i'm facing a problem.
I have a glass panel coming in front of a chrome accessory. All the reflection of the chrome disapear behind the glass panel... See attached pic.
I tried several setting and glass materials but so far i cannot get a good result.
I'm using vfr4 and standard materials from the lib.

Thanks for your help.

[andreas]

Re: Help on glass material

Hello marc,

i think you should try to increase the Max Depth under vray render options -> global options -> materials. The default settings are 2, so you should try at least 4, since you use a solid for your glass...

best regards

Andy

[888.marc]

Re: Help on glass material

Thanks Andy,

You make my day ;D
I really was wondering what was wrong with my setting..

I set max. depth to 4 and then to 3, and now it's working fine.
I noted an sensible increase in the rendering time also...

Cheers,
marc

[andreas]

Re: Help on glass material

your welcome

I set max. depth to 4 and then to 3, and now it's working fine.
I noted an sensible increase in the rendering time also...

yea true, would be nice to have a material and/or object based option how many bounces of reflection are calculated, right now settings apply to everything in the scene, I wonder if that is already on the wish list...

best regards

Andy

[Micha_cg]

Re: Help on glass material

...
yea true, would be nice to have a material and/or object based option how many bounces of reflection are calculated, right now settings apply to everything in the scene, I wonder if that is already on the wish list...

Also this could be a great help if interreflection between blury surfaces cause a strong noise or a long render time.

[andreas]

Re: Help on glass material

Also this could be a great help if interreflection between blury surfaces cause a strong noise or a long render time.

true Micha,
do you know if the cutoff settings in the material options have actual any influence on rendertimes? I usually don`t touch these... what do they do exactly?

Andy

[Micha_cg]

Re: Help on glass material

Yes, it should work. I remember me, that the value was to high at an old previous build and cause strange effects. It makes, that very light reflections will not be calculated. If the value is to high, the reflection calculation stops to early and you miss reflections. I'm not sure, how much time is saved. There is a global version of this option too.

[joe_b]

Re: Help on glass material

The cutoff value tells V-Ray when a reflect/refract ray's contribution is low enough to be ignored. Thus stopping additional ray-traces. If it is too high your rendering will be very fast, but horribly noisy with artifacts. Making it too low can make rendering speeds drop severely ( I think Vlado warns about using 0 as the cutoff ).

[dalomar_cg]

Re: Help on glass material

Also to be noted: A few months ago Vlado changed the way refraction was delt with, thus effectively adding more max depth to refractons (at least this is what Joe told me), so since those reflections are being seen through refractions the amount of actual bounces needed to be calculate increase exponentially with increases in the max depth. That would explain why the render time is increased by just adding a few bounces to the max depth. Hope that makes some sense.