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Toward a more life-like SSS


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A few experiments toward getting a nice human Sub Surface Scattering result.

"Loyd" model by Steve Shelton.

 

Default surface (no SSS) render...

LoydSSSTests.jpg

Sub Surface Scattering renders. Pink and less pink...

LoydSSSTests_001.jpg

I've turned on some Surface "noise" to suggest the pores in the skin.

SSS with Ambient Occlusion...

LoydSSSTests_002.jpg

 

Separate AO render...

LoydSSSTests_003.jpg

 

Curve-Adjusted AO...

LoydSSSTests_004.jpg

 

SSS render composited with adjusted AO...

LoydSSSTests_005.jpg

 

Separate specular render...

LoydSSSTests_006.jpg

 

Composited SSS+ AO +Specular...

LoydSSSTests_007.jpg

 

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There is a Blender tutorial that I thought could be duplicated in A:M here...the issue I ran into was that currently bump maps and materials don't work with SSS (it has been reported).  Displacement maps and materials work with SSS, but the render times would be higher and, depending on percentages, could noticeably bloat the character.  Although for testing purposes, a similar material to the one in the tutorial with a 1 percent displacement should give you a good idea...or you could go the compositing route. 

 

I'll try to render an example tomorrow.

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I'll have to do more testing, but here is a composite of two of the images I rendered.  The first image had no SSS and a displacement material, the second was identical except it had SSS.  SSS requires a lot more displacement than I had time to mess with tonight, I had it set at 30 percent and didn't see anything...so, for tonight, I just combined the two images.  So, there is a little SSS and some displacement.  It's hard to see in a browser, you will get a better view in a paint program so that you can zoom in close.

Of course, to do a decent job of it would require some color maps and I would prefer to use a bump material or map.

 

 

skintest_10_09_2021.png

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19 hours ago, itsjustme said:

I'll have to do more testing, but here is a composite of two of the images I rendered.

It's still a bit dry. Can you make it warmer?

I like those eyebrows. Is that standard hair?

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Here's another test...the displacement is set to 100 and I added some more specular.  I moved the lights to get a better view of the SSS as well.  Currently, the material covers all of the skin, but I'll have to do some experiments with some Groups to have it different on the lips.  Might have to paint it for that.  I'll have to play with the color to warm it up a bit...I'll also look into painting a few areas.  I'll try another one tomorrow.

The hair is the hair material applied to Sam's brows...it does use MuhHair.  However, I think it's picking up some of the changes to the underlying geometry as well.  I might have to move the eyebrows to a sub-dermal layer to prevent that.

Nice tests, Robert!  I think the SSS is a bit too high on them, but the SSS settings I'm using might be a bit too low as well.  For this image I went with the "Skin2" setting (1.3, .85, .56).

 

--------------------

EDIT

--------------------

It was actually "Skin1" settings (1.3, .85, .56)...same settings but wrong name initially.

 

skintest_10_10_2021.png

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I think, for animation, you have to go bigger rather than smaller for the SSS to register. When I look at commercial movie characters they are usually making sure you see it.

Something I wonder is, why do the small SSS setting take longer to render than the big ones? That makes no sense.

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However, here is the same SSS settings but with a much wider light.

 

Either the softer light or the lack of sharper specularity has made it look maybe too gelatinous.

LoydSSSTest014c_000.jpg

 

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I was aware that that is the case for quick renders, but I haven't seen it in a full render.  I also haven't checked earlier versions for quite a while.

Here are some quotes from Yves from this post.

Quote

SSS does not currently wok in Quick render or Progressive (Render-Lock) mode. This is more a user interface issue and I need to implement something similar to "calculate radiosity" in the choreography context menu.

Quote

Indeed, setting the SSS properties on a material is not designed to work and will be disabled in future releases.

 

I'm not sure if anything changed following that post.

Considering the skin texture would be different on the lips, decals for the actual texture and one Group for the surface settings (SSS, etc) would be the way to go.

I got some (what I think are) improvements by dinking with a few things.  Here are some settings I've tried:

Specular size: 3000

Specular intensity: 30

SSS: 3.9, 2.55, 1.68 (Skin1 settings multiplied by 3)

 

I'm currently doing some flattening in order to paint the textures (I've been messing with 3DPaint and Krita along with a drawing tablet) and I've made the eyebrows sub-dermal.  Hopefully, I'll have an improved render in a day or two.

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Quote

Indeed, setting the SSS properties on a material is not designed to work and will be disabled in future releases.

That was the problem, David, thanks!

After transferring my SSS settings to a regular group I was able to render in v15.

render times...

v15  177 secs

v19   39 secs

That is a substantial speedup. Thank you, Steffen Gross! (@yoda64 )

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I don't think Displacement maps work right in SSS.

When this rectangular map is applied to a surface it seems that the 50% gray is being interpreted as negative displacement instead of zero. Ouch!

Edit: this appears to be problem even without SSS

Edit edit: It's a problem with PNG! If that decal is saved as a JPG the 50% displacement works correctly. Must be something to do with the weird way PNG makes its alpha channel.

 

image.png

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I've used OpenEXR quite a bit and gotten good results. It's the only way to not have the stair-stepping on large displacements. The down side is there aren't many paint tools for it. Most of my OpenEXR maps are renders of spline models.

 

New attempt. I made the wrinkles extra huge. If the light catches them just right they look like a shape but otherwise they look like a gray line.

LoydSSSTest016eCOL_040.jpg

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