Dielectric specular value?

[lance_uppercut]

I'm a little confused about Octane's universal material, specifically about what is the appropriate value to use in the 'Specular' color input.

https://marmoset.co/posts/physically-ba ... u-can-too/
https://help.otoy.com/hc/en-us/articles ... -Deep-Dive

Based on the first article, when modeling a dielectric, the specular value should be in the ballpark of 0.04 (linear space). Is the default value of 1.0 appropriate, or should we be locking it to 0.04 for 99% of use cases? I have read somewhere that Unreal engine, for example, defines the reflectance of dielectric (non-metal) materials from 0 % (0.00) to 8 % (0.08) via a remapped value of 0 to 1. Is Octane remapped this way as well, hence the default of 1.0?

Second, as the Marmoset article notes "IOR is another way to define reflectivity, and is equivalent to the specular and metalness inputs". How does octane relate the specular term to IOR? Does it derive specular from IOR and then multiply it by the specular input?

Thanks!

[lance_uppercut]

Thank you! Your website is extremely helpful, I'm bookmarking it! These kinds of practical examples should make their way into Octanes documentation. (Don't get me started on IES lights)