How to convert from Sigercomplex fresnel to normal map in Vray?

[tue_nguyen]

Hi, I tested with vray cloud but it's still not support Complex fresnel (but it's will, chaosgroup support replied my request). My question is can we use other method for get same result with Complex fresnel? I tried with VRayosl and falloff but can't get good image.

[Ihno]

Is this the osl you tryed? https://docs.chaosgroup.com/display/...Fresnel+shader it should give you pretty much the same result, the siger map is based upon it.

[tue_nguyen]

Is this the osl you tryed? https://docs.chaosgroup.com/display/...Fresnel+shader it should give you pretty much the same result, the siger map is based upon it.

Thank you i'm tried wit and i see Siger is based on OSL. But the different is i can't find gamma setting in OSL (complexfresnel has gamma setting). I'm connect it to colorcorrection for adjustment gamma but not good result. And OSL preview isn't same Siger preview (Siger look similar fall off).

[dgruwier]

If you're using this for metals, and you have VRay Next, the metalness parameter on the VRayMtl is basically a native version of complex fresnel.


From Vlado last time it came up:

It would be better (and faster) to use the metalness parameter in the VRayMtl material instead of the complex Fresnel texture. Metalness is more precise. There are some realistic values here:
https://www.chaosgroup.com/blog/understanding-metalness

Metalness in the VRayMtl material is not the same as disabling Fresnel. It does proper metallic Fresnel calculations per micro-facet so it works correctly with the glossy Fresnel option, in difference to the Complex Fresnel texture which ignores this effect.

When creating the conversion table for the blog post, I compared the results from the V-Ray metallic calculations to those of the Complex Fresnel texture and to those of the actual complex Fresnel formula for metals. I've posted my results on Github here:
https://github.com/vkoylazov/metalne...al_presets.csv

"Ole error" is the difference between the formula used in the Complex Fresnel shader and the actual complex Fresnel formula; "V-Ray error" is the error between the calculatons in VRayMtl and the actual complex Fresnel. There are also some charts here for the last metal in the preset list (Cobalt):
https://github.com/vkoylazov/metalne...ess_curves.png

Dotted line is the Complex Fresnel texture, the solid line is the VRayMtl metalness, and long-dashed line is the actual complex Fresnel curve. As you can see, the VRayMtl result is a lot closer to reality.

Best regards,
Vlado

[tue_nguyen]

If you're using this for metals, and you have VRay Next, the metalness parameter on the VRayMtl is basically a native version of complex fresnel.


From Vlado last time it came up:

Thank you alot for this information.