Learning Octane: scattering and glossiness

[ThomasVandenAbeele]

Hi!

Okay, so I am getting to grips with Octane. Very cool renderer but lots to learn.

Underneath is a simple scattering test. My simple question is: how can I make the "outer" sphere have glossy reflections, but still show the same type of scattering behavious - sort of like polished jade spheres.

If I turn down the roughness the spheres become glossy but also show sharp refraction through them. If I turn up the roughness (as shown here) the solid mass scatters nicely, but the surface isn't glossy anymore.

Any ideas? Thanks!!!

[ThomasVandenAbeele]

Step 2: I used the material mixer to mix in a material with glossy reflections. It works in a way, but unfortunately this has pretty severe limitations:

1) Let's say I mix the materials to 50% each. This means I can only reach a maximum reflection strength of 50%, so to speak (because if I mix it in at 50% I can never go above 50% of the strongest reflection level). If I want more reflection I need to mix in more of material B, but then I lose even more of my scattering behaviour in material A...

2) Mixing in material B means I also need to mix in the base diffuse color of material B, thus losing a part of the nice and rich color gradient in the scattering of material A.

Result here below. Is there anything that can be done to keep the nice and rich medium of my first render, and just add the gloss on top (without using compositing)?

Thanks!
Thomas

[juanjgon]

Perhaps you should share the scene to let other users play with it

-Juanjo

[ThomasVandenAbeele]

My bad!

Here you go, just one scene files and one object file (oh, and the render output)!

[alexos]

I think it might work by mixing a few materials and scattering mediums, like so.

This is a five-minutes attempt and admittedly I had nearly no idea what I was doing (the scattering medium and I are sworn enemies) but it does look like a decent starting point. YMMV of course...

ADP.

EDIT: damn, you just posted the scene! Ah well.

[alexos]

Huh, funny, the same material applied to your scene (with caustics blur reduced to 10% and a reflection map) gives this sort of waxy look:

Like I said... Scattering medium! I can't understand you, therefore I hate you!

ADP.

[juanjgon]

You can mix two materials (one sepecular with the medium node and one glossy to add the reflection layer) using the falloff node as key. Attached you have the material preset.

-Juanjo

[alexos]

Juanjo, buddy... Why negative phase?! I mean, it obviously works, but I would never have thought of it. Arrrgh!

ADP.

[ThomasVandenAbeele]

Hi JuanJo!

Good tip using the falloff node to drive the material mixer. If I understand it correctly, the big benefit is that it only mixes in the reflection from material B at glancing angles (where you would want the reflections most anyway), leaving most of the material A visible at the perpendicular angle, right?

p.s. Are you located in Spain by the way? I live in Barcelona for a year, a long time ago!

[juanjgon]

Hi JuanJo!

Good tip using the falloff node to drive the material mixer. If I understand it correctly, the big benefit is that it only mixes in the reflection from material B at glancing angles (where you would want the reflections most anyway), leaving most of the material A visible at the perpendicular angle, right?

p.s. Are you located in Spain by the way? I live in Barcelona for a year, a long time ago!

Yes, I live in Spain, but far from Barcelona

You are right about how the falloff node drives the material mixer. It is a good way to add reflections to any other material.

-Juanjo