Help! Very Confused Setting Up SSS Skin Materials in 2.x

[sikotik13]

For what it's worth, if you are going for accuracy, I'd say you're pretty close given what lighting I see in the rest of the image. People in general tend to overestimate how bright something should look in lighting and I think it's based on dealing with biased rendering in general, which tends towards brighter objects in general. It appears (at least from what I can see in those images) that you are using softer lighting, and not a lot of bright, direct light. Given that, it looks pretty natural to me. If you do have a brighter light (presumably in front of the character and behind the camera), you could try moving it more directly behind the camera or increasing its intensity if you want her to like brighter and still be accurate for how the rest of the image feels, light-wise. Again, my personal opinion, but I think for what I see, it looks good, and possibly more natural than a lot of other stuff I have seen (again, I tend to stray away from reality in general, but I do try to appreciate it when I see it done). Perhaps getting a collection of stock photos to reference would help you feel better about how it looks? Can't think of a good place to recommend offhand, but maybe it would be easier to judge how wrong or right it looks if you could find a series of images of one particular model that appears somewhat similar to your goal in various lighting conditions, so you have a known base and an expected result? It might make the "right" look closer or farther than you think, and you might actually find that real very rarely looks artistic without a lot of crazy stuff being done. It can be and has been done, but the list of photography tricks is quite possibly longer than ones for rendering cheats to get some of those effects.

Short summary, in case walls of me rambling gets tiring for the eyes; I think it looks rather good, and compliments the scene, which seems softer lit. Perhaps you are looking for errors when there may not be any?

[linvanchene]

Thank you all for sharing what you found so far.

While experimenting with this I found something that may or may not be that obvious but would explain why sometimes you see some unexpected color results when adjusting just one surface.

If you are just experimenting with a sphere you have ONE surface that creates ONE volume.

If you want to have the same result on G2F all surface zones need to share the same Transmission, Absorption and Scattering settings.

same SSS material on all surfaces

Nevertheless the way Genesis 2 female is setup you have multiple surface zones.

If you just adjust one SSS material like the face and keep the rest especially the torso that includes the back head map at another SSS color you get a mixed result that combines both the materials of the face surface and the back head surface.

The light enters trough the back head surface and uses that color to tint the front face surface.

SSS orange on face - blue on rest
The face is not orange because light first travels trough the blue tinted volume.

- - -

SSS blue on face - orange on torso
The face is not blue because light first travels trough the orange tinted volume.

You can also observe areas of mixed color results at the border of two surface zones like torso and limbs when different SSS materials are used for the separate surfaces.

- - -

Because of that keep in mind to always adjust the Transmission, Absorption and Scattering settings of all G2F surface zones at the same time.

[Hydra]

sikotik13: I really appreciate your comments. I'm just trying to learn how to do this better. And I can only stare at strangers in malls so much to learn about skin.

linvanchene: I had assumed as much and was concentrating on the ears for seeing the effects of translucence.

If you look closely at Ordiales lighting you may notice something unusual;
viewtopic.php?f=6&t=41584&hilit=victori ... 10#p202567

He's using 3,000 to 100,000 watt bulbs. Here's what a 10,000 watt bulb looks like, and notice what it does to the camera's image;
https://www.youtube.com/watch?v=wvUiYbplNKo

I'm quite familiar with Reality/Lux lighting and its very similar to Octane. I'm also familiar with the same scene. Sun light will blow out in the image, but it won't wreck it. Again its very similar between Lux and Octane. (I do miss Lux's auto camera adjustment, it usually did a good job for adjusting the camera.)

I'd typically light a scene like this with 40-100 watt bulbs, and toss in a mesh or two for high lighting the scene. (Where possible I try to do this.)
http://en.wikipedia.org/wiki/Chiaroscuro

I lit the final scene with 400 watt bulbs (warming 3000 temperature) and 800 watts (cold 6500) mesh on camera. This is about 10 times brighter than what I'd set for Reality/Lux. Its also unusual when you look at how (un) bright the sun is for the ISO 100 film. Since I haven't been adjusting the aperture, that may explain why the lights are so much brighter between what I'd do with Reality and what I'd do with Octane.

Always light to the camera and film. Always.

In the end I increased the light over my test renders, and went with my back scatter Ordiales shader. I'm still looking to learn about this.

PS. Anyone know of hair for G2f that's good enough for Octane?

[Hydra]

So I ran some more experiments to see if there was something else I liked. Based on the Ordiales shader, I set the transmission and scattering to an RGB color, and I set the absorption to grey scale .1, and scattering to 0.

I tested RGB White (produces cold results), RGB off Red which produces darker blood red colors, and RGB SSS. (Teen Josie has a default SSS colour in its textures so I grabbed that.)

It was fun seeing nearly see through stuff, and I did once make the mistake of not setting the back of the head which produced an interesting geletinous looking creature with see through bits.

Notice the light through the ear. Near as I can tell that material is very thin with this model.

Its no surprise, but I'm liking the SSS flavor.

[Hydra]

So, I broke down and bought RedSpec's shader to see what the fuss was about;

I was impressed.

I think that before anyone starts looking into SSS, they really should read this article;
http://http.developer.nvidia.com/GPUGem ... _ch14.html

Looking under the hood, RedSpec is doing everything in the article. Translucency (mostly shows in ears), and sub surface scattering by spectrum which tends to pop more colors. There are about 6 texture/mediums being combined. And I have to say, that it looks like someone Photoshopped the skin.

Also attached here is a simple gloss bump shader (Daz Shader in the database).

[sikotik13]

Having been wavering on biting the bullet on getting those since I could theoretically design the same thing for free (given time and patience), how is the resources used comparison between the two?

[Hydra]

Under the hood it seems weird to me. Its annoying to load right now. The shaders are very complex. So much so that I'm not even sure how to edit Bump. Its referenced at different strengths all over the place. (I think this is to get different SSS Scattering for different RGB colors.)

He's added some textures which are used to define SSS Backscatter Mapping or something. They aren't large or detailed or anything, but they do count against your texture limits. So, not much more memory. That character with clothes and scene was 1GB.

I kinda wish the shaders were generic and combined Face/Nostrils/Lips. I don't know enough to know if or how to combine them. Maybe I'm being old school about this, but it will be a royal pain to edit with Daz's new long and enhanced texture lists.

All that aside, its good. BUY IT It could also be interesting to try and learn from it.

Anyways I 'was' planning to increase the Bump before posting, but I think you'll like this render. Its iPad 3 scale.

[Jools]

I'm having the same experience with Redspec and the DAZ material settings. A custom skin shader doesn't have to be complicated at all to get a reasonably good result. This is a mixed material with a glossy material and spec maps, and a diffuse material with SSS. It might take some time to find the right settings, but then again knowing how your renderer works can be quite gratifying.

[DrHemulen]

Having been wavering on biting the bullet on getting those since I could theoretically design the same thing for free (given time and patience), how is the resources used comparison between the two?

For me, V6 with a fully applied RedSpecs shader consumed about 1.3 gigs of VRAM. As I only a have a 2 gig card, that's pretty useless except for test and portrait renders
I ended up going with the D. Ordiales shader you can also find in the library. Much simpler and less VRAM hungry.

[Spectralis]

Having been wavering on biting the bullet on getting those since I could theoretically design the same thing for free (given time and patience), how is the resources used comparison between the two?

For me, V6 with a fully applied RedSpecs shader consumed about 1.3 gigs of VRAM. As I only a have a 2 gig card, that's pretty useless except for test and portrait renders
I ended up going with the D. Ordiales shader you can also find in the library. Much simpler and less VRAM hungry.

I've bought the G2 RedSpec shaders and the ones on sale at DAZ for specific characters. When I apply the shaders I don't seem to experience a significant increase in VRAM usage. The RS shaders look better than the original shaders in most cases. When using Darius with HDRI lighting he sits much better in the scene with RS shaders. There's a luminosity that helps embed him into the scene. While I appreciate the idea of rolling my own I don't think it's possible for me to achieve the kind of shader results that RS achieve.