VRAY SSS Problems

[hri]

Hi Guys,

I’ve made the transition from Maxwell to Vray a while ago.
Now I’m encountering some untypical behaviour for SSS materials in V-ray.
For a better understanding, here’s a scene I rendered with Maxwell:

The same scene rendered with V-ray.
I used SSS Raytraced (refractive) Material, as a base in a Vray blend material with one coating for the “S”.

Object 1: SSS with variable thickness.
In Maxwell the more thicker the object gets, the blurrier and less visible the checkerboard becomes.
In V-ray the checkerboard remains sharp as long as it is visible. Also the checkerboard is overbright.

Object 2: Objects inside a SSS Material (You can think of little black balls in a glass of milk).
In Maxwell the balls look as expected. In V-ray they look strange.

Object 3: Opaque layer over SSS Material (Partly painted translucent plastic).
In such cases there should be a blurred shadow from the opaque layer inside the volume.
In Maxwell this behavior is obvious.
In V-ray there is no such shadow, it looks as if the letter is done in post.

Here’s a screenshot of the Vray SSS material:

I can imagine that I’m doing something wrong and hope you might have some ideas on this behavior in Vray.
Thanks a lot for your help!

[Morbid_Angel]

can you post the scene so we can have a look.

[hri]

Of course, here you go:

Dropbox - Error - Simplify your life

[hri]

It’s been a while and I am a little bit surprised that no one has a solution for my problem or has similar issues with the VRay SSS Materials in Maya. i hope this time someone can help me Please. I am getting kinda desperate because of this SSS issues, otherwise i am very excited about VRay.

Currently i am doing Grant Warwick’s Mastering VRay course. For the translucent materials he is using the basic VRay material activating its SSS function (under Subsurface Scattering tab). As some of you know, he is working in 3DSmax and with his material setup the SSS is looking as i would expect. I tried to reproduce this in Maya. At first the SSS function of the Basic VRay material dose not have the type setting, which is crucial, as Grant explained. The rest of the settings are there, but when i copy the same values the material is looking very different and even when playing with the values the result has nothing to do with SSS material and is very noisy. I found also some Info that in Maya to use the basic material wit SSS on, one should turn of double sided in the options tab, set IOR to 1 (which is absurd - i think - and its not working) and lower the Refraction Glossiness to something under 1.0. All of these made no drastic change.

1. Here i would like to have a certain opinion, if the SSS function of the VRaymtl in Maya is broken or how the settings differ of those in 3DSmax?

As for me is very important to have the right SSS workflow in VRay for Maya i went back to the VrayFastSSS2 and tried to reproduce the Caramel material.

Here the result and the rendering done by Grant in the course. (I couldn’t extract Grant’s fluid part of the shader ball, so i sculpted a new one, that’s why they are different)

Also my settings. The reflection is plugged as coating in VRay blend material.

My main problem is the absence of blurred refraction of the edges and textures behind the SSS material. In Grant’s material they are present (in the green circles ,close up images). These was one of my problems mentioned in my previous post. And as this is obviously possible in VRay in 3DSmax ,there should be some explanation.

2. Here i would like to have a second certain opinion. Is there no way of getting blurred refraction in VRay’s SSS for Maya?

Basically the way Grant is setting the SSS in the basic VRayMtl is much better although not physically correct than setting up the VRayFastSSS2, on my opinion. For me the FastSSS2 - as i know it - is not as adjustable as the SSS shown in Grants course.
Here one Screenshot as he is setting up the material. The brighter edges are obvious and Grant could fine tune gradually the spread and brightness. Something i could not achieve with the Vray FastSSS2 material. I never got this short spread of the brighter edges.

3. I would like to have some advice on that too please.

That’s it..

Thanks

[hri]

Please somebody.. Even replays like “read the manual” or “use the search function” (which i did) would be better.
I heard from many people, that the people from the chaosgroup forum are very cooperative.

I am not asking about something rarely used.. A lot of people want to get decent working SSS, and blurred refraction is very typical. How do you people make your refractive SSS materials?

I updated the Image of the settings in my previous post. The Options tab was not expanded and the single scatter type was not visible, which is Raytraced (Refractive).

Actually in the official manual for VRay/Maya there is an image showing the FastSSS with scale setting of 100.
“The Single scatter parameter was set to Raytraced (solid). The Marble (white) preset was used for all images.”
Notice, the settings are even with Raytraced (solid).

I tried the same settings and i can’t get the same transparency.

..

[svetlozar.draganov]

Regarding the issue 1 and 2 in the first post, I managed to mimic the Maxwell SSS material behavior with the help of VRayMtl with activated Subsurface Scattering option.
scene: http://ftp.chaosgroup.com/support/scenes/6.ma

As you can see the thicker part of the wedge-object is now blurred and less visible like in maxwell shader. The small dark spheres inside the cube object are also properly rendered.
I am not sure what Grant uses in his course but judging by the things you’ve said he probably uses V-Ray Mtl with activated Sub-Surface Scattering which is exactly what I used in the example above. The SSS feature in VRay material is indeed a little bit different in V-Ray for Maya but looks like it could generate the result you are looking after.

The end result of SSS materials will vary a lot from scene to scene even if you are using the exact same settings so if you are trying to mimic the final result from a tutorial or from our documentation page you will most likely get a completely different result with these settings, that’s because the final appearance of the SSS-shader depends not only from its settings but from the scene itself, the lights, the geometry, other materials etc.

The SSS function in VRay for Maya is not broken, it works but as I mentioned above it uses slightly different algorithm which generates slightly different result.
Please note that the FastSSS material doesn’t support refractive glossiness, so if you are looking for that effect it might be better to use VRayMtl with SSS activated.

I might be able to assist with the caramel scene as well but I’ll need that file so if possible please attach it.

[hri]

Hey Svetlozar!

Thank you very much for the replay!!!
Actually i would prefer to use the VRayMtl wit its SSS, and i am glad that its working. I will download your scene right away and will try to translate the settings to the Caramel material.
If still getting no good results, will send you the caramel scene.

I can send you the scene anyway, if you wish.. Just let me know..

Best
hri

[luis_alcala]

Just wondering if you would be willing to share your findings on this shader? trying to build a caramel shader as well and I wanted to see what conclusions you came up with. Did you end up using the VrayMtl or the VrayFastSSS2? Would be great to see what your outcome was.