Vray sss is it really that bad?

[super gnu]

For an atmosphere, i personally think we'd need a proper solution, with Rayleigh and MIE, but i haven't actually tried setting one up with the integrated scatter volume.
Perhaps because i failed with it when it was alone.

Have you considered trying one of the dedicated solutions, like terragen, for the specific project?
They just improved their atmospheric model to include the "Rayleigh phase function" for added realism.

yeah a dedicated function would be nice.. regarding terragen etc.. im talking about an atmosphere viewed from space surrounding a globe.. there are many hacky ways to get something "passable" but no solution ive found which allows you to dial in atmospheric properties and have something like "earth" pop out of the render.

edit: ive just seen terragen can do whole planets.. reading up now!

[^Lele^]

edit: ive just seen terragen can do whole planets.. reading up now!

You edited the post on my "but..." ahah

[luc_begin]

Here's a link to gDrive to the 28Mb contact sheet that compares Arnold RW and V-Ray's integrated ScatterVolume.
It's three rows, and four colums.
They are all labelled in the top-left corner of each image (small text. zoom.), but the scheme is like so:
V-Ray beauty, SSS, Specular, Colorised Noise Level
Arnold Beauty, SSS, Specular, Colorised Noise Level
The last row contains the absolute difference (or mod(A-B), or |A-B|. I.e. always positive, so always visible.) of the two rows above.

The speed is quite similar for a noise level which is essentially identical ( read the lines referring to max and average. the numbers are close as the render times. We have a slight advantage in noise levels, but it'd need to be confirmed.).
There are a couple of notable differences in the way the SSS solution behaves, between us and Arnold.
a) The scene setup is identical, and the brighter shading seen in the Arnold renders is due to the way its SSS behaves: it will converge to a diffuse BRDF, which isn't quite right for skin. (you can quite clearly see this in the corresponding REs and difference thereof.)
We instead converge to a BRDF with a flatter appearance, not as diffuse-like.
b) With RW there are known issues at grazing angles under some lighting conditions: Arnold seems to converge those areas to white (ish), while everyone else (including us) goes towards a grey (ish).

I'm very exictred to test it out this new SSS shader. It's really hard for me to compare the SSS with a lighting that flat, can't really feel the SSS. Is it going to be soon in the nightly build I'd like to test it. One thing I'm noticing, is let's say around the nostrils there is dark line in the vray one wich should not be there , Arnold is ok in that regard. It's also visibile on other glaring angles on the face and neck. Any idea why it does that ? Also to evalute properly the SSS it would be preferrable without texture, that diffuse is very strong with lot's of baked in wrinfles etc. would be better with fine crisp displacement details and no textures.

[^Lele^]

The second colum is *exclusively* the SSS.
In the V-Ray (and arnold and rMan, in fact) there is no diffuse component at all: they all are SSS+spec, exclusively.
As for the dark line, it's the point b) you quoted me with: both rMan and Arnold have it, the only difference is the way it looks.
For Arnold it converges to a whiter gray than for rMan and us.
Not any prettier, or worse, just different (it's just as visible, once one knows it's there. Part and parcel of all current RW techniques.).

As for lighting flatness, it isn't, it's the SSS with its radius which converges to a flatter look (it's for skin, after all, in these samples.).
The scenes are lit with a dome, and a single spherical light, responsible for most of the highlights.
Check the early posts to see a diffuse render of that same geo and texture.

As for trying it out, it's not going to look any different than a blended setup with scattervolume. You can set it up right now, no need to wait.

[Bigguns]

The second colum is *exclusively* the SSS.
In the V-Ray (and arnold and rMan, in fact) there is no diffuse component at all: they all are SSS+spec, exclusively.
As for the dark line, it's the point b) you quoted me with: both rMan and Arnold have it, the only difference is the way it looks.
For Arnold it converges to a whiter gray than for rMan and us.
Not any prettier, or worse, just different (it's just as visible, once one knows it's there. Part and parcel of all current RW techniques.).

As for lighting flatness, it isn't, it's the SSS with its radius which converges to a flatter look (it's for skin, after all, in these samples.).
The scenes are lit with a dome, and a single spherical light, responsible for most of the highlights.
Check the early posts to see a diffuse render of that same geo and texture.

As for trying it out, it's not going to look any different than a blended setup with scattervolume. You can set it up right now, no need to wait.

When I meant diffuse I meant " color map " . removing it would help to apprecitate the sss better like in the video that vlado posted.

By flat lighting I meant that there is just soft shadow. Having a crisp light would help to see the sss better.

And for the dark line around the nose, side jaw etc. I'm just comparing to reality. In reality we don't have this effect on skin. Is it possible to fix it
or attenuate it ? To me its the only thing that stands out. The rest look's solid and better then alsurface. Probably the best I have seen.

[^Lele^]

Right, i'll prepare you a render of the same mesh (it has no displacement, see its AO render linked above.) with a white scatter color and a directional, instead of area, light.

As for fixing, not at the moment.
Every other implementation of the technique shares the issue.

[^Lele^]

Here's the contact sheet.
You'll notice the darkening always present, and depending for their intensity from the scale.
The mesh, you may have noticed, is truly low res for this kind of work (specular, AO will give you clear clues. It's a decimated scan, full of fans and nests, and twisted triangles.), so most of the issues will be gone entirely with a properly modelled and triangulated mesh, and a physically plausible radius.

[Bigguns]

Yeah, i wouldn't be obsessed about the performance metrics: i am sure i made mistakes setting the scenes up, and a pro of any of the other engines would wipe the floor with me.
The takeaway is indeed that we are very comparable for speed and features, and that we are finally a lot easier to set up and use.

For an atmosphere, i personally think we'd need a proper solution, with Rayleigh and MIE, but i haven't actually tried setting one up with the integrated scatter volume.
Perhaps because i failed with it when it was alone.

Have you considered trying one of the dedicated solutions, like terragen, for the specific project?
They just improved their atmospheric model to include the "Rayleigh phase function" for added realism.

I could see for the mesh, like the eyebrows etc. But about that dark line on glaring angle, in Arnold it's at least twice less strong. Do you know what is causing it ? and if there is a way to mitigate it ? Other then that it look's solid. In arnold the randomwalk2 creates some greenish or bluesish ( depending of the color of the sss ) in creases etc. Vray have it too, I don't know if it's at the same extend since I haven't tried the shader yet. So to make it near perfect, fixing or mitigating this black line stuff would be great and then mitigating that greenish blueish color would make it a top skin shader. Only thing missong from there would be to have a first layer of glossy refraction to see the fur going through the skin like in real life but this I think it will take a while to happen haha.

[^Lele^]

I believe I've already replied to all your queries.

[Bigguns]

Hi Lele, is this new sss shader in the nightlybuilds ? I'd realy like to test it out. I tried to blend a sss volumetric shader with a vray mat but I get weird problem in reflection in the lips etc and the diffuse color don't lokk right etc.

[kosso_olli]

The speed is quite similar for a noise level which is essentially identical

What is the reason for the Arnold specular being very clean, and the V-Ray specular being very noisy in your comparison?

[^Lele^]

Arnold used fixed sampling, V-Ray used Adaptive, and as such the beauty noise level is lower for us.
If i rendered with fixed, and not matched times, we'd be clean too.