MODO glass vs Octane specular material

[riggles]

I'm trying to learn the difference between how MODO renders glass and how Octane does. Since Octane has a dedicated specular material, it seems to work differently. For instance, glass has relatively low direct reflectivity, but high fresnel reflectivity. So in MODO I might start off with 10% reflection and 90% fresnel, with 100% transparency, 1.55 IOR, and no diffuse color.

However in Octane, there's no separate fresnel or diffuse control (which is probably more physically accurate), just specularity and index. But a low specular value just makes the glass look dark. Why is that? I need to turn up specularity to 0.8-1.0 for it to look right. Of course, I get white fireflies all over with it set to 1.0, but it looks better there. Also, Octane's transmission color seems much more sensitive than MODO's transparent color control, which basically provides the equivalent function.

So, I guess I'm basically looking for help understanding how this specular model works, so that I know why I'm getting different results.

[Obizzz]

And the roughness value seems to affect both refraction and reflection. What if I want a frosty material with glossy reflections?

[riggles]

And the roughness value seems to affect both refraction and reflection. What if I want a frosty material with glossy reflections?

Martin, I think in that case you would want to use the Scattering medium in the Spec material. Basically like adding SSS in MODO. That way you could keep the roughness down.

Like this:

Glossy and frosty :)

[Obizzz]

Thanks!

I haven't ventured far beyond the basics yet and as you say some parameters are a bit different compared to Modo. (and other renderers I've used)

[riggles]

Thanks!

I haven't ventured far beyond the basics yet and as you say some parameters are a bit different compared to Modo. (and other renderers I've used)

It's funny that i've still found it easier to test material settings in the Octane standalone then the MODO plugin, because of that handy material preview mode it has.

[face_off]

I'm trying to learn the difference between how MODO renders glass and how Octane does. Since Octane has a dedicated specular material, it seems to work differently. For instance, glass has relatively low direct reflectivity, but high fresnel reflectivity. So in MODO I might start off with 10% reflection and 90% fresnel, with 100% transparency, 1.55 IOR, and no diffuse color.

However in Octane, there's no separate fresnel or diffuse control (which is probably more physically accurate), just specularity and index. But a low specular value just makes the glass look dark. Why is that? I need to turn up specularity to 0.8-1.0 for it to look right. Of course, I get white fireflies all over with it set to 1.0, but it looks better there. Also, Octane's transmission color seems much more sensitive than MODO's transparent color control, which basically provides the equivalent function.

The plugin is not (yet) converting the Modo glass material properties (other than opacity) to the Octane specular material. But it would be easy to do. Let me know what "conversion" you would like, and I'll code it. Funk came up with some suggestions in the TEST thread.

And yes, high specular values overpower the scene and cause fireflys. adjust the index or specular pins to get it to correct levels.

Paul