Reflectivity & Edge Tint Colors

[Peter Arcara]

Hello everyone,

Just started testing Arnold, and I was pointed to the alShaders by Pingo in the APT C4D 2 videos.

I am trying to make a metal shader (nickel), and I am trying to find the place where the reflectivity & edge tint color come from. I've seen the values in the alShaders reference documentation, and I've looked at the charts on refractiveindex.info. However, I can't seem to find anywhere that gives me the numbers in the documentation. I've plugged in the gold values, and it looks great. Just wondering where to find more values for other metals.

Thanks in advance!

- Peter

[Anders Langlands]

The colors in the docs are ones I hand-tuned to match a full-spectral calculation so they are very accurate. You can generate pretty good approximations yourself quite easily from refractiveindex.info as follows.

For nickel, go here:

http://refractiveindex.info/?shelf=main&book=Ni&page=Rakic

Enter 0.65 as the wavelength, then scroll down to the Reflection calculator. The value 0.64915 is the red channel of the Reflectivity parameter. Then do the same thing at 0.55 and 0.44 to get the green and blue values. This gives me Reflectivity = (0.64915 , 0.6103, 0.53092).

To get edge tint, change the angle of incidence in the reflection calculator to 80 from 0, and do the same thing again (check that the 80 angle doesn't get reset to 0 when you change the wavelength), using the non-polarized value, R. This gives me Edge tint = (0.64184, 0.64359, 0.6353).

Plugging these into alSurface I get this:

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[Peter Arcara]

Thanks so much! That makes a lot of sense. I didn't even think of going though the individual wavelengths.

Nice job on the shaders!

- Peter