Chaos Corona for 3ds Max > [Max] Tutorials & Guides

Realistic materials experiment

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Ludvik Koutny:
Playing with blender cycles i stumbled upon sort of Pixar-PBR-ish technique of material creation. It's slow to set up and it probably renders bit slower too, but it seems to produce some nice results.

Basically, the idea is to create CoronaMTL, set it's diffuse color to complete black, and plug your diffuse color to the reflection color slot. Set Fresnel IOR to 999 and reflection glossiness to 0, or maybe just a little bit higher if base layer of your material is not as rough as wood on my example.

Then plug that into blend material, and plug another CoronaMTL as a second blend layer. Make it mirror (0 diffuse, 1.0 reflection, Fresnel IOR 999)

Then blend them using Falloff map set to IOR mode.

In my example i distorted wood coat (mirror material) with little amount of bump and glossiness mapping.

IMHO it looks little better than regular approach. It won't probably pay off for entire scene because of rendering time and set up difficulty, but if it's object of interest in a close up shot, it could help I think.

Check the pictures for shading graph and examples:

Ludvik Koutny:
Made a gif to compare with regular methods...

maru:
This looks interesting but I completely don't get how it works. For me the result looks like wooden carpaint. ;) What's the difference between using bitmap plugged to reflection color + glossiness 0 and bitmap plugged to diffuse color? Do you have any articles on that Pixar-ish material creation?

Ludvik Koutny:
It's wooden carpaint indeed. It's not related to disney PBR material in any way. It's just similar to it in a way that disney PBR gradually blends betwen diffuse and reflection, so diffuse material is considered as material with very low reflection glossiness.

It's not from any article, just personal experiment. I think it simply looks better, more natural. More close to the wooden materials i see on architectural photos.

Juraj:
That's very interesting honestly.

But I see quite few issues, both theoretically and visually:

Visually: They look metallic, and shouldn't. Part of blame for this is imho that 0-glossy (absolute roughness) in Corona is still more specular than should. It's not diffuse enough, hence why your base layer looks more metallic than lambertian in very unnatural way.
              Coating makes it look like a fully varnished wood, despite seeming attempt at having at least somehow rough wood.

Theoretically: Blending with (even though slightly distored) mirror to simulate fully grazing reflection, creates zero ramp-up in material roughness. But what should happen, is not only ramp-up in intensity, but also roughness, the specular reflection needs to look more rough at 0 angle, and rise up according to IOR. Your example, only ramps up intensity, creating varnished coating instead, no matter how rough the base layer is.
Now I understand blending mirror coating and fully rough base should blend the glossiness as well, but somehow it doesn't, or doesn't well.

To me it doesn't look more real at all and can't work imho in such simplified way. I have more issue with the coating than the base layer. Maybe try some rough example instead ?
 

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