Pretty all in the question, but to add a bit of detail, I'm asking this regarding to the reflectance curves of refractive.info website wich have P/S/non polarized curves.
I'm using Cycles fresnel to a color input of an emission shader.
- In fact I must be more precise, I'm looking without any transformation in the color management, so pure data, and I know I will not have the exact reflectance curve with this scene.
- To be more precise, those are the curves I'm speaking about:
And to respond to @JtheNinja I assume the k fresnel coefficient extinction is the part of the curve that drop down before jumping to 1 on the P polarized.
If I'm right about the k, we have this hardcodded to the fresnel node:
My curve is x compressed at the end because it's hard to deal with grazing angles and making a linear progression. But you can see the curve drop down even with the default fresnel node.
At the begining I was choosing the non polarized but looking at the fresnel curves I have, they look closer to the P polarized, so the question remains. What are P/S and non plolarized and which one to choose if I what to make fresnel with RGB curves?