V-Ray alSurface

[Pionier]

I played a bit with the new shader, it's great ! So I can reply to my question, it doesn't work with RT GPU for at the moment.

The glossy fresnel is a cool thing, especially when working with Megascans or textures from Substance Painter. And having two reflection layers is great too, I have never understand why the V-Ray material doesn't have at a least clearcoat layer.

[ATTACH=CONFIG]33537[/ATTACH]
[ATTACH=CONFIG]33538[/ATTACH]

For those interested in Megascans textures :

> when it's available, use AO map in the diffuse slot above albedo, in multiply mode
> when using V-Ray Material, use inverted Roughness map with sRGB colorspace for the glossiness, it's one map less to store compared to manage gloss. and rough. maps. Plus the conversion of the glossiness map to roughness is broken in Bridge.

does the AlShaders version match what did you have in painter/megascans? I notice that with high rougness edges are become very bright actually (like on your Vray version on the left). I've seen that they fixed it in Corona 1.5 also: https://corona-renderer.com/blog/cor...-1-5-released/

"The GGX BRDF was modified in the CoronaMtl to offer the full glossiness range, bringing it in line with emerging industry standards and removing any physically incorrect dark or light “halo” at the edges of rough objects. This means it now gives expected results for all Glossiness and Fresnel values."

So may question would be - is this actually a bug of current version of VrayGGX for modo, if so - can this will be fixed just like in Corona?
And what I have to do to get access to night build with AlShaders?


Thanks,
Peter.

[vladimir.nedev]

So may question would be - is this actually a bug of current version of VrayGGX for modo, if so - can this will be fixed just like in Corona?

I think the glossy fresnel will find its way into the V-Ray Material.

And what I have to do to get access to night build with AlShaders?

If you have a V-Ray for MODO license, you should have access to the nightly builds here : https://nightlies.chaosgroup.com/#/karoshi
The new ones are at the top. If you don't have access, even though you have a license, send an e-mail to support and they will fix it.

Greetings,
Vladimir Nedev

[vlado]

does the AlShaders version match what did you have in painter/megascans?

Yes.

So may question would be - is this actually a bug of current version of VrayGGX for modo

No, it's not an actual bug, the VRayMtl works as it is supposed to for the moment. The glossy Fresnel feature which you are referring to is already in the nightly builds for 3ds Max and soon V-Ray for Modo. Until then, feel free to use the alSurface shader which does the same thing.

Best regards,
Vlado

[John_Do]

No, it's not an actual bug, the VRayMtl works as it is supposed to for the moment. The glossy Fresnel feature which you are referring to is already in the nightly builds for 3ds Max and soon V-Ray for Modo. Until then, feel free to use the alSurface shader which does the same thing.

Best regards,
Vlado

Great ! So is the glossy Fresnel in VRayMTL supported by RT-GPU, unlike alSurface shader ?

[vlado]

Great ! So is the glossy Fresnel in VRayMTL supported by RT-GPU, unlike alSurface shader ?

It will be, when we are finished with it.

Best regards,
Vlado

[Robert]

Oh.. just seen its in the latest build for Mac too.. wow.

[Robert]

Seems like Backlight and all Refraction things still missing, sadly. I was hoping for it to get rid of the 2-sided shader.
Anyway the alShader is lot closer to what the Modo shader does, it feels more modern and refresh to old style Vray Material. Really a cool development.

[vlado]

Seems like Backlight and all Refraction things still missing, sadly. I was hoping for it to get rid of the 2-sided shader.

Will get to that a bit later.

Best regards,
Vlado

[Pionier]

OK, I got it too, thank for an info where to find it

@John_Do, may I know how did you setup maps from painter into AlShaders material, are you using Arnold preset when exporting the maps?

[John_Do]

Hey Peter, I'm using the PBR MetalRough preset because it does the job with every shader. Important thing is the colorspace of images in Modo.

Albedo / Specular ( in case you're using it ) : sRGB ( default )
All other maps : Linear ( including Roughness, Bump, Disp )

You can simply invert the roughness map to convert it to a glossiness map, in case you would use the standard VrayMtl. You can even mimic the alSurface behavior by diminishing the reflection color in the VrayMtl and increasing the IOR ( to compensate lower reflectivity at facing angle ). It does the job but it's far from perfect ( and from alSurface look )

For alSurface, use Reflect2 channel for first specular lobe. It's the one with the glossy Fresnel. The Reflect1 seems to be used for clearcoat, it's enabled by default, don't forgive to set it to 0

[Pionier]

Ach I see,

I was trying with Arnold preset and was wonder where did you plug f0 map , I will try to use reflect2 when get back from work, thanks John!

[Robert]

What I really like in the alShader is that reflection amount and color are separated. May sound odd for Vray user, but in Modo I learned the advantage of that, the color is really just a tinting you use seldom, what you more often need is the intensity. So if you map the specularity/reflectivity of a shader with RGB map, you always need to desaturate it first, not with alShader anymore.

[Pionier]

Nope, I still can't make it look right, PBR Metal Rough preset have also Metalic map, did you use it?

I attached two images to illustrate how my setup is looking, both in vray ggx and vray al shader.
Or maybe setup it correctly and this how it suppose to look like

[John_Do]

No I don't use it, since we can't at the moment. There is a metallic / dielectric switch in the original shader, but Vlado doesn't have integrated it yet in the V-Ray version. For the metallic parts extracted from SP projects, I assign a specific part / material to the part and do a second material, with the correct gradient in Reflection color. Or you can use the Diffuse color map ( which has the metallic specular ) and disable fresnel. I advise to not using the IOR for metal since it gives incorrect results ( darker part just before F90 ) :



I see you have cheated a bit the aiSurface, using the Reflect1 for metallics part. It seems working ! BTW you can see that there is no "white halo" in the aiSurface version on the front parts of the toy at grazing angle, it's obvious !

On the other hand I think the V-Ray setup is wrong, with Fresnel IOR and Reflection Color maps exported from SP you have to disable "Fresnel Reflections" in the VrayMtl Properties. You can see the metallic parts don't look correct.

[Pionier]

No I don't use it, since we can't at the moment. There is a metallic / dielectric switch in the original shader, but Vlado doesn't have integrated it yet in the V-Ray version. For the metallic parts extracted from SP projects, I assign a specific part / material to the part and do a second material, with the correct gradient in Reflection color. Or you can use the Diffuse color map ( which has the metallic specular ) and disable fresnel. I advise to not using the IOR for metal since it gives incorrect results ( darker part just before F90 ) :

[ATTACH=CONFIG]33797[/ATTACH]

I see you have cheated a bit the aiSurface, using the Reflect1 for metallics part. It seems working ! BTW you can see that there is no "white halo" in the aiSurface version on the front parts of the toy at grazing angle, it's obvious !

On the other hand I think the V-Ray setup is wrong, with Fresnel IOR and Reflection Color maps exported from SP you have to disable "Fresnel Reflections" in the VrayMtl Properties. You can see the metallic parts don't look correct.

John, first of all, thanks for your support

Indeed, there is no metalic/dielectric switch yet. That would nice small improvement to have in future.

I think you are right about disabling "fresnel reflections" in VrayMtl, this way render look exactly the same as the one with alSurface. Which is what I wanted to achieve and I what I believe is "correct".

And yes, I was trying to do metallic part with Reflect1 maps.