Details about used Fresnel Equations in rough conductor BRDF

[kobabulbul]

I want to know the used Fresnel Equations and the associated default parameters for:

bsdf = mi.load_dict({
'type': 'roughconductor',
'alpha': 0.2,
'distribution': 'ggx'
})

The documentation says it follows the routine of Microfacet Models for Refraction through Rough Surfaces by Walter et al. The presented Fresnel Equations there is for unpolarized dielectrics. Is it used in the model?

How can I change the parameters?

I hope it's okay I pose this question here.

Best regards and thanks in advance.

[njroussel]

Hi @koba341

Have you taken a look at this page yet? By default the material is set to none which means a relative IOR (eta) of 0 (and imaginary part k is 1). I think it's pretty easy to follow this logic in the source code too if that helps.

All of these parameters can be changed when instantiating the plugin with load_dict or when updating them with mi.traverse(). Refer to the tutorials/documentation for examples of that.

[kobabulbul]

Thank you very much, the source code was very straight forward and helpful. Indeed, the Fresnel Equations for Rough Conductors differ from the one in Walter et. al.

Thank you also btw for making this renderer. I'm doing optical metrology in the thermal infrared and I think your python package can be very helpful. I try to use it for simple simulation purposes. I have the general problem that I don't exactly know what the commands do, but with the source code at hand it shouldn't be a big problem anymore.

Best regards,
Hoschang Noori