GGX in corona

[fla]

Hey!

I think there was once a topic regarding the GGX materials in Corona. (

)
Do we still need to merge multiple glossiness maps in one material, to achieve high realism in metal materials?
Or does Corona do it automatically and there is no use of using that workflow?

I think Corona does it, but I wanted to be completely sure.
Thanks
cheers

[Eddoron]

Corona uses the GGX model.

From the features page:

GGX & PBR Workflow

Corona Renderer uses the GGX microfacet model to deliver realistic–looking metals and other glossy materials. Our implementation of the GGX model fully conforms to the industry standard physically–based rendering (PBR) workflow. This model produces much more plausible results compared to legacy models such as Blinn, Phong, or Ward. Because of our state–of–the–art implementation, using this model does not incur any speed penalty unlike in other microfacet models.

[fla]

Thank you!

[maru]

Do we still need to merge multiple glossiness maps in one material, to achieve high realism in metal materials?
Or does Corona do it automatically and there is no use of using that workflow?

I am not sure what exactly you mean. Can you tell us where exactly is this mentioned in the video? Searching for that part by scanning over 1 hour vid is not that great idea. :)
Generally if you need to control the glossiness of the whole material, then you can just adjust the glossiness parameter.
If you need the glossiness to vary, then you should use a bitmap to drive that.

[Nejc Kilar]

@fla,

Afaik GGX has the "wider" specular lobe that Grant was showcasing by default. So you essentially get that nice softness effect to your specular reflections just by turning on GGX (default in Corona).

Neil Blevins has a cool article posted on his webpage - http://www.neilblevins.com/cg_education/ggx/ggx.htm

V-Ray has extra control for that as it allows you to modify the size of the lobe using the "tail falloff" parameter while in Corona you can't really control it.

With that said, the workflow of blending multiple reflection layers will probably give you the most artistic control over all the options. Will you notice the difference? Thats another question :)

[Cinemike]

With that said, the workflow of blending multiple reflection layers will probably give you the most artistic control over all the options. Will you notice the difference? Thats another question :)

Well said, my thoughts exactly about a lot of endless "fine tuning".

[Nejc Kilar]

With that said, the workflow of blending multiple reflection layers will probably give you the most artistic control over all the options. Will you notice the difference? Thats another question :)

Well said, my thoughts exactly about a lot of endless "fine tuning".

Indeed :high_five: :) From my personal experience I find the way that the glossiness behaves under grazing angles the least of my concerns - Tone mapping, textures, subtle anisotropy in materials are almost always something that I think can be improved way before I'd even tackle that. At least with the GGX brdf that is.

[fla]

Sorry, for not replying for so long.
That's exactly what I was referring to @nkilar.
I agree, this kind of attention to materials is needed only for closeups imo. In wider archviz shots I wouldn't go as deep.
What I found very useful though is using fresnel maps for both, IOR and Glosiness slots. With GGX you get pretty close to results from the posted tutorial from Grant Warwick. But the material stays very simple to modify as well. Which I think is essential.

I'm not acquainted with "tail falloff" in 3dsmax. But I use frensel in a filter which I can control with a curve. It works great.