Index of Refraction

[tomcole]

what is the difference between the IOR setting in the reflection layer and the one in the refraction layer? (see image attached)

[thomthom]

Re: Index of Refraction

The Fresnel IOR when used in reflection layer is how the lights reflects off the surface of the material.
The refraction IOR is how light breaks as it passes through it. (Like when you see a stick standing in water, below the water it looks like it breaks of in an angle.)

[tomcole]

Re: Index of Refraction

I assume you mean the refraction ior (refraction layer) but than what is the refract IOR in the reflection layer (not the fresnel IOR)?

[40th]

Re: Index of Refraction

The refraction IOR is how light breaks as it passes through it. (Like when you see a stick standing in water, below the water it looks like it breaks of in an angle.)

[thomthom]

Re: Index of Refraction

I was referring to the refraction layer - not the refraction IOR in the Fresnel map. Not sure what the Fresnel Refraction IOR is...

[Jackson_cg]

Re: Index of Refraction

OMG this is the most confusing render discussion yet! LOL

Fresnel IOR in the Reflection Layer controls the viewing angle relative to the surface at which light starts to reflect off that surface.

Refract IOR in the Reflection Layer controls the viewing angle relative to the surface at which light starts to pass (refract) through that surface.

This is why these two figures should usually be the same, as they are usually directly proportional.

IOR in the Refraction Layer controls how light changes direction when it refracts (passes) through a surface.

No refraction layer means light passes directly through it without changing direction, which in reality would mean it has the same density as air (or whatever substance you are viewing the glass through).

It confused me at first as seeing "Refract IOR" and "Refraction IOR" in two separate places is a little baffling. You just have to remember that reflection is the ability of any surface to bounce light back, while refraction is the ability of a surface to allow light pass through it. Materials like glass have a mix of both as they allow a lot of light through, but also reflect a little and this ratio is highly dependant on the viewing angle. Glass viewed at an extremely acute angle (i.e. your ear pressed against the window) will reflect almost 100% of the light, while when viewed at 90° to it's surface it will reflect much less. It's this ratio which is controlled by the Fresnel parameters.

[artchung]

Re: Index of Refraction

I think what Tomic means is why there is refract IOR in reflection layer. Also what is that different from the IOR in the refraction layer. Am I rite? Tomic.

Honestly, I dont exactly know what refract IOR do in the reflection layer. If anyone knows, please advice. : ) Thanks!!

[Jackson_cg]

Re: Index of Refraction

OK, I edited my post above to make it (hopefully) a bit clearer and more comprehensive.