Rough Specular reduces specularity amount?

[Morbid Angel]

Maya version should be available on Github already. Isn't it?

yeah you are right I recall reading about it. I'll look into it a bit later

[sharktacos]

Thanks! Yes, the VRayAlMtl material handles this better as the Fresnel is included in the BRDF calculations.

Best regards,
Vlado

Vlado, my understanding is that you are planning on incorporating per micro-facet Fresnel into the VrayMtl. Is this something that might be happening soon (i.e. nightlies)?

[vlado]

Vlado, my understanding is that you are planning on incorporating per micro-facet Fresnel into the VrayMtl. Is this something that might be happening soon (i.e. nightlies)?

Define "soon" This is the rough plan, yes, but I don't know yet when I'll get to it. It's not terribly complicated, but I have some other stuff to complete first.

Best regards,
Vlado

[sharktacos]

Define "soon" This is the rough plan, yes, but I don't know yet when I'll get to it. It's not terribly complicated, but I have some other stuff to complete first.

Best regards,
Vlado

good to know, thanks!

[sharktacos]

Having now spent some time with the VrayALMtl shader it has left me very much impressed. For some time I have been wanting greater predictability when creating, specifically, dielectric materials which utilize glossy maps. For me, either correcting the native VrayMtl or fully implementing the ALsurface shader would be of highest importance.

fascinating tests. I went to try this out myself today and ran into a roadblock: The ALsurface shader apparently does not have any tail falloff parameter (gamma) for the GGX spec. Bummer. It would have been interesting to see what the results would have been on the microfacet Fresnel when the tail/gamma is lowered below 2.0.

Update: So I asked Anders why he did not include a tail falloff parameter in the ALsurface GGX/GTR. He said it was because you can't do anisotropy easily with GTR. But the VrayMtl already has anisotropy with GTR. So hopefully, with that hurdle already crossed, it won't be too hard for Vlado & Co. to incorporate microfacet Fresnel into the VrayMtl. Fingers crossed that "soon" comes soon

[Ihno]

I'm trying the new options of the Vray Mtl in the nightlies.

There is a radio button "Use glossiness/Use roughtness" which seem to simply invert the glossiness parameter.
And a checkbox "Glossy Fresnel" which seem to enable the rough spec functionality.

Am I right about that? Does the use gloss/rough option simply invert the gloss and nothing else?

Im asking this because it is somewhat inconsistent and may cause confusion.
The roughness parameter actually has nothing to do with that.

Why isn't it a checkbox called invert glossines or PBS gloss? Would be more clear (at least for me).
But why adding this at all?
We could just use a output map with invert opton enabled.
Since this is not typical for you, I think I've misunderstood something

[vlado]

Does the use gloss/rough option simply invert the gloss and nothing else?

Yes, that's all it does. I was wondering whether to rename it to a checkbox "invert glossiness", but then again many PBR shaders specifically talk about "roughness" and it's not immediately obvious that it is related to glossiness.

Why isn't it a checkbox called invert glossines or PBS gloss? Would be more clear (at least for me). But why adding this at all? We could just use a output map with invert opton enabled.

Yes, you could. However if your entire scene is set up this way, filling it up with Output maps is probably an overkill (not to mention unnecessarily slow).

Best regards,
Vlado

[LudvikKoutny]

Yes, you could. However if your entire scene is set up this way, filling it up with Output maps is probably an overkill (not to mention unnecessarily slow).

I always thought output map in 3ds Max is one of the fastest map they have. That using it should make almost 0% difference in rendertime. That's why I try to use output as much as possible instead of ColorCorrection for example.

[Ihno]

Yes, that's all it does. I was wondering whether to rename it to a checkbox "invert glossiness", but then again many PBR shaders specifically talk about "roughness" and it's not immediately obvious that it is related to glossiness.

Hm, and calling it PBR Mode or PBR Glossiness would suggest your material isn't physical if turned off I guess...
Anyway, I now know what it does. Thanks for clearing that up!

In my opinion moving that option down to options and the Glossy Fresnel up to the BRDF or the reflection would make more sense.
Im not using any engine which uses that fancy inverted glossiness.
Glossy Fresnel on the other hand is something I'll propably use alot.
But thats only my optinion lets see what the masters say.

[vlado]

Glossy Fresnel on the other hand is something I'll propably use alot.

Glossy Fresnel is on by default now for new materials; after a while you won't have to change it, hopefully

Best regards,
Vlado

[Rens]

That's great news! Thank you!

[piotrus3333]

is glossy fresnel RT CUDA compatible?

[zeronove]

Glossy Fresnel is on by default now for new materials; after a while you won't have to change it, hopefully

Best regards,
Vlado

sorry guys, but now I'm a bit lost about all this "glossy fresnel thing"

- is it a lower glossiness (or higher roughness) for surfaces viewed at grazing angles? ...yes or not?
- is it a dimmed reflection amount for surfaces viewed at grazing angles? ...yes or not?

...if the last one is correct, what about stronger reflection (driven by IOR values) for surfaces viewed at grazing angles?

[sharktacos]

Does that mean other materials (for example SSS2) will have glossy Fresnel, or is it only on the VrayMtl?

[sharktacos]

sorry guys, but now I'm a bit lost about all this "glossy fresnel thing"

take a look at this explanation:
https://labs.chaosgroup.com/index.ph...lossy-fresnel/