MR Index of Refraction Facing ratio

[Maximus]

Hey guys, i have a problem which is bugging me since a lot now..

I need to blend different shaders one on top of each other, creating complex effects and texturing, the problem is i've noticed both mr and vray in 3ds max have the ability to use the blending mode with a fresnel fallof, based on index of refraction, which makes the shading be physically correct related to the IOR and the actual material you are creating.

Now i've banged my head on the wall for the past 2 hours tryin to replicate this thing inside Softimage without any success. Here is the thing, to do the fresnel effect i would use the Incidence node, but this node has nothing to do and its not driven by the index of refraction, its more "artistic" oriented tool, you move the sliders and the fresnel effect changes as you like it. But again its not that correct.

So what i thought was.. ok lets see if mental has some IOR node i could use, with my big surprise i typed "index" in the search toolbox in render tree and a mib_refraction_index popped out.
I tried to use this node and set the IOR here to drive the incidence but again i cannot be sure this is the correct way to do so. The results are quite different from the 3ds max "Fresnel" texture at same IOR values.

Here are couple of screens to illustrate what i mean. This is the normal setup in softimage where you have the incidence controlling the blend between the 2 shaders, again this has nothing to do with IOR and the fresnel effect its not controlled by that. The Incidence is set to surface/camera standard.



Here is a screen of 3ds max with the option to drive the fresnel effect based on a IOR.



Basically, how can i have the fresnel effect driven by the IOR in Softimage? This is vital to create some realistic materials to me.

Thanks, Max

[Fer]

Did you use the dielectric shader ? it have both reflection and refraction output IOR.

[Maximus]

Did you use the dielectric shader ? it have both reflection and refraction output IOR.

I'm not sure what should i do with this shader, the Dielectric has just 1 output, i cant find the IOR output as you said, but even if it has where should i plug it into?

[Fer]

in the weight of a mix 2colors, choose "output reflection energy" in the Dielectric shader and insert an IOR in index of refraction slot. I think the reflection energy is an intensity multiplier or a bias ?

edit: or a gradient mixer

[Saturn]

another option you may want to use is the mia_multioutput material and use the refra_level output.
Set your IOR and done.

[Maximus]

another option you may want to use is the mia_multioutput material and use the refra_level output.
Set your IOR and done.

Hmmm i tried both architectural_multi-out and mia_material_x refr_level but it doesnt work for some reason, the dielectric does.
Bit confused

[Saturn]

what isn't working ?

If you plug it to the surface slot of your material do you see anything ?

[Fer]

You should crank up the reflectivity or the refraction at 1.

[Maximus]

I rather use the dielectric, i am tryin mia material_x and this is what happens:
set refraction to 1, plug the refr_level output to the weight of the mix2 colors (or even surface of the material). When then i play with IOR the effect doesnt change while it does with dielectric.
So something is missing.

[Fer]

Did you check default IOF on ?

[Maximus]

i am sorry i'm quite confused.



Beside the fact that both the renders are quite different in terms of Fresnel effect (which confuses me more since i dont know now which one is the correct one), the mia material is more diffused while the dielectric (right apple) is less.
If i change the refr_Ior in the mia_material_x nothing changes it always render the same image with the same amount of falloff. so its not reading the IOR properly.
While in the dielectric everything works fine. (and no, i didnt forget to click the "auto" refresh in the apple shaderball) it simply doesnt work.

[Fer]

You should check BRDF Fresnel, and see if there's a difference, since you need to activate it to use the index of refraction, right now you're using the manual one. Try the mia architectural one, it's more easy to navigate.