I have expertise neither in physics nor in theater. But I do want to chime in to suggest that any time you're about to make a categorical statement like "fresnel is not a noun" in response to someone using it that way, it's worth pausing. Regardless of your certainty, there's rarely a well-grounded reason to think your view is more correct than theirs.

All language is contextual. Fields have jargon. And so many arguments on the internet arise when people from different contexts make unnecessarily strong statements insisting that their usage is correct. Instead, pause and consider whether there's a more valuable approach such as curiosity.

It's a noun in CG/VFX.

"Can we change the Fresnel to get less reflection?"

"No, it's a physically-based renderer - change the IOR"

"but, that'll change the refraction angle..."

"Yep, split them into AOVs, and let comp deal with it."

> "Fresnel" is not a noun.

It is in stage and film lighting [0], which made this headline confusing to read.

[0] https://en.wikipedia.org/wiki/Fresnel_lantern

Like "diffuse" and "specular", it's certainly used as a noun.

Each field can make up whatever jargon is convenient.

If we were talking about optics, then 'diffuse' and 'specular' would be adjectives that describe reflections. Fresnel reflection tends to mean specular reflection. The author sounds sensible when he recommends that specular reflections be implemented using Fresnel's math. That is how specular reflections work outside the computer.

I would just call it polarization. Or if you wanted to be more specific, angle of reflection dependent polarization.

> "Fresnel" is not a noun

Says whom?

Simon