Does fresnel goes away on rough surface

[HapZungLam]

According to this video "https://www.youtube.com/watch?v=xMpDTk3DTW8" by CynicatPro saying that fresnel will be hidden or bounces off to other direction due to a rough surface.  Most of the game engine i believe it calculate by itself.  I wonder if it is true and if so, what is the math behind it.  eg, how rough of a surface will cut away how much of fresnel.

[HapZungLam]

The PBR guide from marmoset even suggest that the rougher the surface the dimmer the reflection should be. I assume this rule only applys on dielectric materials.

I realize that the preview in SD.  if I put roughness to 1.0. the power of reflection does goes down.  But is more like 0.2 than absolute 0.

[Wes McDermott]

The PBR guide from marmoset even suggest that the rougher the surface the dimmer the reflection should be. I assume this rule only applys on dielectric materials.

I realize that the preview in SD.  if I put roughness to 1.0. the power of reflection does goes down.  But is more like 0.2 than absolute 0.

Hi,

That is correct, the rougher the surface, the dimmer the reflection will appear. This is for both metal and dielectric. However, the same amount of light is still reflected, it just appears dimmer because the light is scattered.

Cheers,
Wes