Vray BRDF roughness capability in Modo question

[Christopher3D]

I'm a possible new Vray for Modo user. I'm investigating whether I want to invest in Vray (I probably am) and had a question about its material system capability. I also have TheaRender. It's an awesome renderer (GPU/CPU hybrid, great material system, etc.), but its drawback is it doesn't have a Modo plugin, so you have to export everything to it which is a pain.

It has one advanced material function I'm curious to find out if Vray can also do.

A surface's overall roughness can change according to the view angle. So you can have a very rough surface at low incidence, but at high incidence it becomes more mirror like. This really ads realism to renderings because it's something that happens in the real world a lot.

https://thearender.com/forum/viewtopic.php?f=17&t=13379

You can see TheaRender's explanation for the feature at the above link.

Can Vray do this? If it can't, does Vray support Gradients used to control roughness?

Thanks.

[pixelwerk]

V-Ray supports by default the GGX-BRDF shading model, means microfaceted highlights and reflections. Even MODO since 901 supports a similar approach with it's introduced "pysically based" shader setup. You can still rely on gradients to control the amount of roughness controlled by the incidence angle. Both, MODO and V-Ray support the default gradient texture from MODO for this

[vladimir.nedev]

I don't think we have this behavior built-in in any of our shaders.
But yes, you can achieve it with a gradient texture in incidence mode.
It works in our GPU renderer too.

There is a demo build on the site you can try out.



Greetings,
Vladimir Nedev

[Christopher3D]

Ok, thanks for the reply. They also just released a blog posting further showing its effects. I think this is something you guys may want to consider as a fundamental function of Vray's material system. In TheaRender it's super easy to use, you just turn it on as a material option. It has a couple of basic parameters (to control the roughness parameters), but the default settings work pretty well as they are. This material property is represented everywhere in the real world, and once you know to look for it's pretty obvious.

http://blog.thearender.com/tips/usin...s-with-metals/

Knowing that I can at least use a gradient in Modo to simulate it in Vray will be great.

Thanks for your help.

[vlado]

The GGX and other microfacet BRDFs already incorporate this effect for most real-world materials you may want to create. You can always map the glossiness/roughness if you want to further enahnce it.

Best regards,
Vlado