controlling Octanes fresnel

[mitchino]

I understand that as Octane is unbiased, it automatically makes reflective surfaces more reflective at glancing angles - is that correct?

Is there a way to control the effect? I have a glass bottle render and my bump looks great on the reflections at the front of the bottle, but it's too much at the sides - can I fix this?

[mitchino]

anyone got any advice on how to control the fresnel effect?

[zoppo]

The visible fresnel is controlled by setting the index number.

If you want to control the bump you have to use the node editor and combine your bump node with a falloff node.

[mitchino]

OK - so the bump round the sides of my bottle render is too strong, i.e at the glancing angles, but I like it at the front of the bottle. My glass texture is mapped with cubic projection. If I add fall-off to the bump, will it fade away as it goes round the bottle?

[mitchino]

I've been reading up on the fall off node, and I have created a mix material, containing two materials, one with bump and one without. I then piped a fall off node into the amount channel of the mix material, and I can fade out the bump according to the glancing angle.

BUT - it's only an opacity fade between the bump and non-bump materials. How can I use the fall off node to fade between a high bump and a low bump according to the glancing angle? Is this possible?

[mitchino]

I think I've cracked it!

If I put a noise node and an RGB spectrum node set to 50% grey into a mix node and then pipe a fall off node into the amount channel, then pipe the mix node into the bump channel of my material, I can use the fall off node to control the bump so it appears higher at direct angles and lower at glancing angles. And it is actually adjusting the height rather than just doing an opacity fall-off.

Is this a good strategy? It works for me!

That was a bit of a head scratcher...

[zoppo]

That is a good way too. But what I meant is to for example multiply the falloff node and the bump node (image or whatever).
And then set the falloff from gray to black or from white to gray or whatever you need.

[mitchino]

can you show me a node tree of what you mean?

[mitchino]

I want to do the same thing with a normal map i.e. use a fall off node to control the normal map so at direct angles there is a normal effect and at glancing angles there isn't. How would I set that up? If I do it the way I did it with bump where I used a 50% grey, what is the equivalent with a normal map?

[zoppo]

I have to say your setting is way better than mine. I seem to have mine mixed up with something because I couldn't get it to work how I had it remembered.
So thanks for teaching me how to do that