Dispersion & Rough (Mix) and Noise

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chiraagm
Posts: 6
Joined: Tue May 11, 2021 8:34 am

Dispersion & Rough (Mix) and Noise

Post by chiraagm »

I am trying to create realistic diamond jewelry renders and went through a few engines (Cycles, Octane and LuxCore)

While cycles is an amazing engine not the best for diamonds (especially since it lacks dispersion).

Octane was my winner until I came across LuxCore. Octane has this feature to have roughness and dispersion both enabled at the same time in Specular materials (like glass/diamonds). Just like anything else in the rendering world, nothing is perfect, so just like there should be no fully white or fully black, in the same manner there needs to be a very slight roughness (somewhere around 0.001 to 0.002) to create a realistic diamond.

To achieve this I am using two Glass materials with the same IOR, the only thing different is one has dispersion, and the other has Rough enabled (0.0015). I am currently mixing these materials through a mix node with 15% (rough glass) -85% (dispersion glass). Using just Dispersion glass, I am getting relatively noise free renders after about 500 samples (2880 x 2400), but the image only looks realistic with the mix node (some amount of roughness), in which case I am getting a fair amount of noise.

Is there a better way to achieve roughness and dispersion, so as to not create so much "noise"

I understand that increasing the sample count seems the easy thing to do, but that would pretty much double/triple my render times
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Dade
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Re: Dispersion & Rough (Mix) and Noise

Post by Dade »

chiraagm wrote: Wed May 19, 2021 5:57 pm Is there a better way to achieve roughness and dispersion, so as to not create so much "noise"
You could try to create some roughness in pure glass trough (very light, high resolution image or procedural) bump mapping :idea:
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chiraagm
Posts: 6
Joined: Tue May 11, 2021 8:34 am

Re: Dispersion & Rough (Mix) and Noise

Post by chiraagm »

Thanks Dade

Will try it out
Martini
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Joined: Fri Nov 23, 2018 11:36 am
Location: Australia

Re: Dispersion & Rough (Mix) and Noise

Post by Martini »

Dade wrote: Wed May 19, 2021 8:56 pm
chiraagm wrote: Wed May 19, 2021 5:57 pm Is there a better way to achieve roughness and dispersion, so as to not create so much "noise"
You could try to create some roughness in pure glass trough (very light, high resolution image or procedural) bump mapping :idea:
Sorry if this has been asked before, but... why is dispersion not calculated when using rough glass? Is there some technical limitation, or was it just lower priority and nobody implemented it yet?

Does Octane need to use a different model for specular materials to allow it?
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