fresnel question

[barilla2000]

I have consulted the manual and didnt find anything so here goes:

What does the refract color do under the fresnel map settings?
I mean, if the reflection or refraction is controlled by the fresnel color and IOR,
why this extra refract setting here?

By default it is turned of (100% black).

[barilla2000]

Re: fresnel question

Ok I found some reading and wanted to run it by You guys to make sure Ive got the question right:
What does the refract color control when aplied as a fresnel map on a reflective layer in a vray material?
Why, if ever, would one want to use a fresnel map on a refractive layer?

[remon_v]

Re: fresnel question

If I'm correct the refraction color in the fresnel settings determence in what direction the light will be bounced of your object.

[Jackson_cg]

Re: fresnel question

"Refract Color" under Fresnel settings doesn't actually have any effect on the direction light bounces, it determines how reflective the material is when it it viewed from less reflective angles. For architectural glass it should really not be 0,0,0 black as glass is still quite reflective viewed straight on- better to set it to a luminance of between 10 and 50.

For the vast majority of reflective materials the IOR values for Fresnel and Refract should be the same as they're usually directly proportional.

The examples below show the SU model setup- 5 horizontal planes with 5 reflective materials which are identical apart from different Refract Color Luminances. At the end of these planes a striped pole shows how the materials reflect. As you can see in the V-Ray render below the Refract Color Luminance has no effect on direction of light (there's no distortion in the reflection), it only affects how reflective the material is when it is viewed at an angle less than 90° to the surface. Technically the individual planes are being viewed at slightly different angles due to the camera position, but it's set up with a focal length of 200mm so the effect is minimal.

[thomthom]

Re: fresnel question

Ah, didn't know that about glass. That's a good little tip.