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SSS for Skin

harlequin-3dharlequin-3d Posts: 0
edited December 1969 in Carrara Discussion

So what is the verdict on this? Heard some people like it, others don't.
Has anyone had good results using Subsurface scattering on skin?
What settings did you use?



  • evilproducerevilproducer Posts: 8,493
    edited December 1969

    If you installed Carrara's native content there are hi res skin shaders for M4 and V4 under the browser's shading tab. Scroll down until you find the skin directory. The icons look like fleshy sphere's. Look for ones that say GI. These use SSS and may give you a starting point to experiment with. You may have to hover the mouse cursor over the file name to reveal the full name with GI at the end of the file name.

    To use the skin shader, load an M4, V4, H4, A4, Girl 4, etc. into the scene. In the scene instances, expand the figure's hierarchy and select Model. Look above for the shading tab and select that. Now, drag the icon for the skin you've selected and drag and drop it onto the multi-colored ball at the top of the shading domain list in the shader tab. It will load and replace all the domains at once. Depending on your computer, this could take a minute.

    According to the manual, using GI in the renderer will give the best results for SSS and Translucency.

  • harlequin-3dharlequin-3d Posts: 0
    edited December 1969

    Duh, I saw those but I didn't try the GI ones. GI is Global Illumination right?

    I thought GI was a, shall we say "substandard" lighting method...No?

  • evilproducerevilproducer Posts: 8,493
    edited December 1969

    GI is Global illumination. It's not substandard, but it does take longer to render and isn't really suitable for animations. There are methods to simulate GI and I would highly recommend that as you learn lighting, you look into those.

    There are a couple components to Carrara's GI settings. Briefly, Skylight allows you to use HDRIs, Realistic Sky, colors, etc. in either the Atmosphere (Realistic Skies) or the Background (colors, image maps HDRI) in the Scene's effects tab. Skylight will treat items in those categories as lighting models and generate light based on your image or atmosphere. Skylight does not to my knowledge calculate reflected light.

    Indirect Light calculates reflected or bounced light, but not atmospheric or image based light models. Additionally, it also can use objects with a glow in the shader's glow channel as a light source.

    Photon settings and accuracy seem fairly scene dependent. I've used low accuracy and l,ow photon counts and had the image look fine, and then in another scene the same values look like crap. My rule of thumb has been to start low and go up, rather than crank everything to it's maximum and take a week to render.

    Another tip to using Skylight and Indirect light is to turn off the scene's ambient light. It can make the final image look washed out. If you use any lights in your scene, you may need to lower the brightness for those as well.

  • DartanbeckDartanbeck Posts: 12,045
    edited December 1969

    Also, you may certainly use "GI" shaders without using GI lighting - I do it all the time ;)

  • evilproducerevilproducer Posts: 8,493
    edited December 1969

    Also, you may certainly use "GI" shaders without using GI lighting - I do it all the time ;)

    yes, you can use them in a scene without GI. I'm just pointing out that per the manual, the SSS function and the Translucency function work better with GI. Has to do with bounced light.

    Personally, I think SSS takes to long to calculate in any render, so I avoid them like the plague. What I do is put the image map from the color channel into the glow channel and lower it's brightness to around 10% to start. I make further adjustments based on the lighting in the scene.

    Two examples. Both human figures in each image use the glow method.

    2000 x 1500 - 756K
    2000 x 1500 - 822K
  • CarltonMartinCarltonMartin Posts: 147
    edited December 1969

    SSS without GI produces "unexpected results." Sometimes that's fine, sometimes not.

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