skin shader a la Alsurface pleaseeee

[^Lele^]

Lele, don't grab Aisurface. take ALshader here : http://www.anderslanglands.com/alshaders/index.html( BTW , the way that material is build is awesome, you can do a lot of thing with it.. skin, metal,glass,etc not hairs though, that's why they added a alhairs ) , I posted the link in my first link .. the standard skin shader in arnold suck.. dont even bother with that one.

The alsurface in directionnal mode retains more details then the vray sss2, has better back scattering, less sss bleeding , better default reflection especially the fresnel , feel's more dpeth to it,better back scattering , less greenish with high sss radius, the 3 sss color don't affect the overall color like in the vray skin wich makes it WAY more easy and better looking then the vray skin..etc etc. I cannot do a render comparaison , I use max.. and it's not available ( for now ^^ since autodesk buy solid angle.. we will have it sooner then later.. probably next year ) , but at work guy's do shading in Arnold.. and I saw it.. I know the result of the sss2 by now... so I can compare easily the feel of both.. strongness and weakness.. what would be cool also for a new skin shader in vray would be to have control of the sss in shadow region, in reality it get redisher.. wich we don't have now.. we just have a redish line in the transition between lighted and shadowed region. Also, have a first scatter layer that does glossy refraction to see the fur going fading through the skin would be awesome.. the alsurface don't do that.. that would be awesome to have.. would help tremendously to integrate better all the eyebrows, eyelash etc on the face of a character.. because now they feel like pasted in 2d over the character..

And yes Vlado, the method distribution make's a huge difference, you should play with the shader, you'll see. In directionnal, it look's way better for skin.. the devil is in the small details you know

<3
I'll know what to look for now, Luc, thanks a LOT!

[Bigguns]

Great! Let me know if you are willing to write a new skin shader for Vray, I would be more then glad to test it out and give you feedback to make the best skin shader ever

[vlado]

So I'm looking at the sources of the alSurface shader and it looks quite straightforward to write an equivalent for V-Ray; I have a question though: do you care about being able to choose the type of the SSS diffusion profile, or just the directional one will be fine?

Also, do you care about being able to choose between Beckmann and GGX speculars, or just GGX will be fine?

Best regards,
Vlado

[^Lele^]

The directional, of the four profiles, seems to be the only one to provide for single-scatter.
And Beckmann for Skin is likely way too sharp, and way too little retro-reflective (GTR gamma is 10, i think, for Beckmann: tight!).

[Akira]

Hi, a colleague and friend of mine did a nice and funny little tutorial on creating a setup for Emily in Arnold.
It looks really good and is hilarious with audio.
So entertaining
Check it out:
https://vimeo.com/163019016

[Bigguns]

Lele: Do you think you can do something similar for Vray ?

Akira: Yeah I've seen it ^^

[^Lele^]

Emily comes with a wealth of references.
I don't see that arnold exercise matching any, but perhaps i am mistaken.
Granted, the specular looks prettier related to the SSS, when i look closely at the pores, while i used the provided reflection map and tweaked GTR to get close (and quite failed in some areas. Not least as i didn't realise the map had a baked in sRGB profile.).
If what you're asking is MY take on Emily and its shading, well, yes, i guess i could indeed match that, minus the specular, which would still look good, but not the same.
It doesn't look good, overall, to me, but then this is an opinion (ie. worth nothing to anybody else.), not maths.

This is the contact sheet (24 megs, quite big) with the emily setup i shared the scene for.
https://drive.google.com/open?id=0B1...TIyUTJpNUxENEU

[vlado]

Luc, can you answer the two questions above (about the scattering mode and the specular BRDF type)?

Best regards,
Vlado

[Bigguns]

Lele : No, I mean do you think you can do a shader in Vray similar to alsurface, with directionnal SSS , a 3 layered sss ( that don't affect the overall coloration but just the sss component ,etc ) and better reflection then what we have now ? I know the emily 2 project I'm part of it.

Vlado : Sorry I missed you'r post! Wow if you can do it quick Vlado I would be super glad to test it out on my new character I'm working on!!! I'm very exited to hear that . For skin, sure the directionnal is the best one of the four. would be cool to have all of them honestly, but let's start with directionnal at first so it's less work for you For the reflection, I would say let's have 3 relfection layer, first 2 in GGX and the last one in Beckmann. Why Beckmann, because we need a crisp profile ( in Vray I use a layer in blinn mode ) to get the wetness relfection layer, it's a crisp small reflection layer and it creates nice effect on the skin. and why 2 GGX, because 2 gives more flexibility then just one and like that we are sure to not have to blend it with a vray blend to get the exact effect we want. GGX I use it for the main relfection layer, so as the oilness of the skin. but since skin has very specific reflection , I often blend 2 GGX to get a better effect. EDIT : There is a thing I found in Vray, I don't know if it's in the nature of the GGX ( and maybe it's why they use Beckmann in Arnold ) but it creates some wierd fresnel reflection when fresnel is on, at least it's not good fresnel for skin.. like I get fresnel effect around the edge of the nostril wich make's them look really CG... I have to uncheck fresnel and use a custom one to make it better.

And BTW Vlado, do we have that udim supported in vray 2d displacement? I had to switch to 3d for my personnal project since she has udim.. and the displace is slower,.. takes more ram and look less good then the 2d one

[Bigguns]

here's a great exemple to see the difference between Beckmann and GGX : http://adaptivesamples.com/2014/06/2...-distribution/ So, as we can see, the GGX has way too much fresnel effect for skin... Beckmann look better for that regard . ( iT's why I deactivate the fresnel effect for skin with GGX .. it just look wrong for skin.. ) so , can we have both or something better, a more realistic fresnell effect on the GGX that match more skin ? I never seen any skin shader having the perfect skin reflection.. but I guess it's why he used Beckmann in his alsurface for the skin .

The more I look at that exemple.. the more I think that 2 layers of Beckmann would be good for the main reflection and a third layer for the wetness ... let me know what you think Vlado. If you can do a shader and let me test it out , I'll tell you and show you what work's the best. I never use Backmaan since Vray don't have that one has far as I know. I also seem to prevent bouncing reflection in some area like the ears lets say, I think Alsurface shader have an option for that to prevent the reflection to bounce all over like in the ears and create indesirable sort of fresnel reflection.. I don't know too much how to explain it without an image ...

[^Lele^]

here's a great exemple to see the difference between Beckmann and GGX : http://adaptivesamples.com/2014/06/2...-distribution/ So, as we can see, the GGX has way too much fresnel effect for skin... Beckmann look better for that regard . ( iT's why I deactivate the fresnel effect for skin with GGX .. it just look wrong for skin.. ) so , can we have both or something better, a more realistic fresnell effect on the GGX that match more skin ? I never seen any skin shader having the perfect skin reflection.. but I guess it's why he used Beckmann in his alsurface for the skin .

The more I look at that exemple.. the more I think that 2 layers of Beckmann would be good for the main reflection and a third layer for the wetness ... let me know what you think Vlado. If you can do a shader and let me test it out , I'll tell you and show you what work's the best. I never use Backmaan since Vray don't have that one has far as I know. I also seem to prevent bouncing reflection in some area like the ears lets say, I think Alsurface shader have an option for that to prevent the reflection to bounce all over like in the ears and create indesirable sort of fresnel reflection.. I don't know too much how to explain it without an image ...

Directional SSS, no, not yet. As you know V-Ray has the one diffusion profile, which isn't the same as Arnold's.
As for the rest, yes, it's how Emily's skin was built (not with the skin shader.), but it's pointless as Vlado got coding.

V-Ray, however, sports the full Generalized Trowbridge-Reitz BRDF, so you get GGX with a gamma of 2 (the default) and Beckmann with a gamma of 10.

Also, i didn't use Frensel OR GGX in Emily (rather a very low gamma GTR), nor i layered more than the single spec, for the reasons i already outlined in the piece i published a year and a half ago: there was a PRECISE target to hit, adding 2 or 10 layers would have changed nothing in that regard.
Perhaps you can do better (hitting the target, in the fashion i endeavoured to: sharing a contact sheet of renders alongside photographic and measured references, and a file for people to have a play with): i'm well aware of my limits, and i don't dream for others to share them with me.
In fact, your renders do look stunning, so perhaps you may find a better way to shade Emily, regardless of render engine.

[joconnell]

It'd be interesting to get Lukáš Hajka involved too, he found that there was a few things in Arnold's skin that worked better for him, it'd be great to find out what those were and see can he be tempted back

[Bigguns]

yes I was about to say the same, since he tried both personnally and he prefered Arnold one for many reasons. As far as I know, from his post on cgfeedback, he said that Arnold had control in the reflection so it don't bounce back and fourth ( I think you can limit it to one bounce or something ) and create unwanted reflection like in the ears, better SSS layered mtl that the sss don't affect the overall color but just the sss component, better lighting and he certainly like the directional mode ( the other mode seems good for other sort of sss, like if you want to do a candy etc ). but the best way would be to ask him and he likes the most and what he would like to see in the vray skin. and later on, if we can get the first layer of the skin to be refractive so we can see the hairs going throuth the skin.. that would be crazy awesome! no skin shader for now can do it! and it's a must.. so that our eyebrows etc don't look to be like 2d pasted fur on the skin..

Lele: For the reflection , I found it impossible to get a realistic skin reflectance with only one layer of refletion.. I use more an artistic approach to it then a physically based one.. since I found no brdf that correspond exactly to skin.

[^Lele^]

no skin shader for now can do it! and it's a must.. so that our eyebrows etc don't look to be like 2d pasted fur on the skin..

Not quite.
The skin shader may not, but the SSS shader in V-Ray DOES have refractive raytraced mode.
This is why i always prefer to build my layers through the additive blend shader: control and accuracy, on top of more flexibility, compared to the skin shader itself.

Lele: For the reflection , I found it impossible to get a realistic skin reflectance with only one layer of refletion.. I use more an artistic approach to it then a physically based one.. since I found no brdf that correspond exactly to skin.

Eh, yes.
The thing with Emily was that my "creative" hands were somewhat tied by the references, and by the use of the provided reflection map (so, when that goes black, and it does, there is no BRDF which will ever be of help in those areas.).

The usual approach for non-scanned stuff is unquestionably quite different, on that i agree with you completely.

[Bigguns]

the sss2 in vray has a raytrace mode, but first you don't have acces to make it glossy.. wich is useless for skin.. and it's not working as one would expect for skin.. sinc eit's not just the first layer of the skin that became translucent it's the whole thing.. so again useless for skin.