Using wavelength values for R-G-B from wavelength in nm to RGB/hexadecimal converter based on efg’s Computer Lab: Spectra:
R = 0.65 µm
G = 0.51 µm
B = 0.44 µm
*1 µm = 1000 nm
Inputting those values into http://refractiveindex.info/ wavelength and using the low end graph, taking into account only non-polarized values (green curve) for each color channel, this is the result (or by sliding on the curve and manually typing those entries into RGB Curves node):
This image is manipulated. Every curve represents non-polarized curves in respective color channel.
Translating angle (0-90°) to decimal (0-1) values one can use simple cross calculation as with calculating percentage. Example:
Looking for decimal value of 25° angle:
90° = 1
25° = x
90x=25 >>> x = 25/90 >>> x=0’27777…
So decimal value of 25° angle is 0’27777.
Here are comparative results (fresnel VS facing) to see what is correct based on measurements (facing looks correct - notice the reflectance on the edges 90°)
There’s also noise added for roughness.
Here’s how nodes look:
… and here’s the LayerWeightFacing.metal+rough.IOR.RGB.curve.blend
Hope you can learn something.