PBR IOR Setting for Wet Surfaces

CreativeSheep

When needing specularity on a mesh, I suppose depending on your render you use, you may be using PBR reflect, what was surprising to me, as I'm use to the old workflow, although understanding PBR probably won't take me long is; index of refraction plays a role when attempting to give a material specularity, whether to make it shiny or wet.

Is adjusting the IOR setting within PBR reflect suitable for creating wet surfaces or I should not be adjusting the IOR setting ?

Eric Chadwick

My understanding is no, high IOR does increase reflectivity on facing surfaces, but it's not physically correct, you're telling the water surface to act like a metal.

Which might look ok in the current lighting, but will probably look wrong in different lighting. Defeats one of the biggest "wins" of using PBR... that your physically correct surface will look good in all lighting situations. 

CreativeSheep

What method would make the surface look wet, like a wet clay ? I can only work PBR Reflect.

Eric Chadwick

There are two main PBR methods: Specular/Glossiness, and Metalness/Roughness. If you mean the former, then for water use a dark gray Specular and a bright Glossiness.

CreativeSheep

@Eric Chadwick
More wet clay is what I'm after, although I only have; Reflect, Roughness and Reflectance color and roughness to adjust ?

Eric Chadwick

What software is this, and where did you get the shader? A screenshot of the shader Ui would help.

CreativeSheep

Eric Chadwick

Which software, and what renderer?

CreativeSheep

Houdini, Mantra.

Eric Chadwick

Hmm can't really help you there, non realtime renderers tend to do things slightly differently from each other.

It does look similar in setup to V-Ray though. In V-Ray, water uses black diffuse, white reflect, white refract, zero roughness, and IOR 1.33. For wet clay, you could use a clay material with a clearcoat on top. Not sure how Mantra materials are set up, but in 3ds Max with V-Ray I would use a VRayBlendMtl, with the clay material under the water material.

CreativeSheep

What is Vray water material, or is it simply just a clear coat ? If anyone can post a screen shot of the Vray water material that would be helpful ? What does the default Vray clay material look like, as I only found this ?

Eric Chadwick

There is no default. You make your own. I found it pretty straightforward once I understood how each of the main material inputs work. You can search the web for material setup tutorials.