Falloff node - Simple HOWTO

[niuq.cam]

Very interesting Fooze. Thank you !
I will also tests.
Niuq

[archigrafix]

Fooze
About your architectural glass material: the effect you achieve is called Fresnel reflexion, but I thought unbiased renderer like Octane were capable of this through the IOR value?

[archigrafix]

Nobody to reply about the fresnel reflections subject????
Surely I will make a topic about that cause it is something important to be precise with IMO

[FooZe]

Hi archigrafix,

Sorry for the late reply.
Yes, IOR can be used to do this. But the plus side of using a glossy material with fresnel/falloff is that it is more controllable, and does not effect the appearance of the scene through it.
This is a very good thing when using opacity to allow some rays straight though for lighting and casting shadows inside the room. At the moment due to limitations, light will still be "stopped" by the specular material, even if it has full transmittance. Hence the use of opacity to let rays straight through as if the glass was not there.
If you were to use a specular material with IOR and some opacity you would see some strange doubling up of the scene behind the glass. (one for the straight through rays from the opacity, and another from the rays that are effected by the IOR on passing though the specular material).

The glossy material with falloff controlled opacity and full reflection make for a simple, fast and easy solution.

Cheers
Chris.

[Olitech]

Hi archigrafix,

Sorry for the late reply.
Yes, IOR can be used to do this. But the plus side of using a glossy material with fresnel/falloff is that it is more controllable, and does not effect the appearance of the scene through it.
This is a very good thing when using opacity to allow some rays straight though for lighting and casting shadows inside the room. At the moment due to limitations, light will still be "stopped" by the specular material, even if it has full transmittance. Hence the use of opacity to let rays straight through as if the glass was not there.
If you were to use a specular material with IOR and some opacity you would see some strange doubling up of the scene behind the glass. (one for the straight through rays from the opacity, and another from the rays that are effected by the IOR on passing though the specular material).

The glossy material with falloff controlled opacity and full reflection make for a simple, fast and easy solution.

Cheers
Chris.

Is this still a viable workaround for the modern (2014) 2.xx versions?

[FooZe]

In the latest versions you can use the "fake shadows" option on the specular materials to "let light through" easily.
Have a go and you will see what it does. It will pay attention to the materials transmission and also the IOR in a limited way.

[lukas8410]

Useful explanation thanks!

[Olitech]

In the latest versions you can use the "fake shadows" option on the specular materials to "let light through" easily.
Have a go and you will see what it does. It will pay attention to the materials transmission and also the IOR in a limited way.

Hi Fooze,

I think we are talking about a Fresnel falloff in the reflection, not the refraction.

Best,
O

[haffy]

How do you set this up on lets say a Glossy Material for a cloth material? Is it in the Specular input?

[whersmy]

Haffy, for cloth I almost always use the Sheen option, Be sure to tick the BRDF GGX model.