Fresnel Reflections on Transparent Glass

[martin walker]

I dont seem to have any luck when using Fresnel Reflections in a vray material...especially in an external glass scenario. As soon as I switch it on I get almost no reflections and a dark looking material...any suggestions ?


material settings attached

[martin walker]

Heres a screen shot to show what Im getting

[Trevor Tizard]

If you increase the Fresnel IOR value from 1.6 the reflections will be brighter

[AJLynn]

What's it reflecting? Do you have an environment for it to reflect?

[martin walker]

yes, theres a sky box in...you can see it on the screen shot.


I get really nice results with Fresnel reflections on shiny stuff...cars etc...nice glancing / fall off reflections, but for some reason cant get a decent result with glass

[AJLynn]

I think the render is accurate - you're looking at it almost straight on, and Fresnel will give it a low reflectivity at that angle. If you want it more reflective, like Trevor said, you can increase the Fresnel IOR.

[Timothy Saunders]

The thing with fresnel reflections is that it is almost giving the glass the reflection vray thinks it should have. Perhaps I'm incorrect, but I don't use fresnel reflections on glass. That way I can be the one telling it how much to reflect. The best thing to do is search for images that have a similar glass, similar light settings (exterior), and a similar angle on the glass. then try to match that. Different glass reflects and refracts differently. To me, fresnal reflections are better for small non-architectural glass like a mug, or something.

[Sawyer]

What I have started doing is putting a fresnel falloff in the reflect slot and putting the reflect color swatch to white. Then I can reduce the fresnel effect of the map I can tweak the reflection a bit.

[martin walker]

Originally Posted by Timothy Saunders

The thing with fresnel reflections is that it is almost giving the glass the reflection vray thinks it should have. Perhaps I'm incorrect, but I don't use fresnel reflections on glass. That way I can be the one telling it how much to reflect. The best thing to do is search for images that have a similar glass, similar light settings (exterior), and a similar angle on the glass. then try to match that. Different glass reflects and refracts differently. To me, fresnal reflections are better for small non-architectural glass like a mug, or something.

thanks Tim....your thinking is the same as mine...I just thought I was doing something wrong !!!

[Christopher Nichols]

Everything in nature has a fresnel falloff in the reflection just like everything in nature is effected by gravity. The issue with the fresnel check in vray is that it does not account for the face forward reflection. Instead of using the fresnel checkbox, use a falloff map in fresnel mode and make the forward face slightly brigter than black. That should give you want you want.