A few scattered ideas - a more coherent version is going to come in the long treatise I’m writing. With lotsa pics to prove my points. But you gotta wait some ‘cuz real life, y’know.
No piccies in this post ‘cuz my internet connection hates me tonight. But I haz links. Very recommended ones. Read on, and ye shall find.
—CRUCIAL: SSS scale 0.1, SSS shading rate 1 - ask theSea if you don’t trust an unknown like me, it was him who guided me towards this in our old lab thread; also consult 3Delight docs re:scale conversion! Up your scale, and the shader thinks you’re feeding a doll to it instead of a lifesize human!—-
—- CRUCIAL, pt. II: if you’re using SSS at all, all your lights must cast shadows, IBL must use AO. Otherwise you’ll get light rays where they don’t belong (c) theSea in the old lab thread, again—
1. The diffuse maps we’re using have SSS already “built in” - for one simple reason: we can’t take SSS out when we photograph a real person (ask Mec4D if you don’t trust me). Only the blood-based portion of it if we photograph a corpse…
2. This is why, if we’re using blood-based colours for SSS, it’s better to drop the diffuse strength somewhat (or to desaturate your maps and stick the diffuse in the SSS colour, but that won’t really work for the default UberSurface because its SSS colour map control is broken).
A cyan tint in the diffuse colour multiplier is a neat addition if you want a paler-yet-scattering character.
Read this, BTW: http://www.bossanovatech.com/Articles/Article P&G on skin translucency - 2006.pdf - might spark interesting ideas. Gotta love solid science!
3. The original UberSurface is a frellin’ beast to work with. Its SSS controls are limited, and the colour parameter is extra sensitive at the physically correct scale. Pale, very pale yet not too pale - try these: 249-255-221 or 234-251-255. Only allow 255 in the red channel, if you want a Martian (or a living human out of a zombie/alien diffuse map).
And yeah, go wild with the SSS colour if you do want a cool alien.
4. Unlike its cute li’l sister UberSurface2, US prefers energy conservation to be respected re:strengths of diffuse and SSS channels, otherwise it does tend to produce overexposed images. Diffuse strength 75%, SSS strength 25% - works more or less OK.
5. Ditch the “SSS maps” unless you’re obsessed with making ears glow. If you are, paint your ears white and the rest of the map a shade of grey. Other than that… look at how deep light actually scatters in skin and then do tell me you need those mythical maps (bones getting in the way of scatter?? unless you’re holding a candle in your palm, it means someone failed their anatomy class) http://orion.bme.columbia.edu/~hillman/Skin_Imaging.html
// sorry for causticity, but this is one of the worst pet peeves of mine //
Skin is skin is skin. Physically it’s made of the same cells all over your body, and they scatter the same. Your diffuse maps are going to handle the melanin irregularities like moles, palms/soles etc.
5. But you NEED tons of intricate specular work (and preferably blurred reflection as well, ‘cause Fresnel DOES NOT attenuate spec in the original US, only the reflection) to make it look prettier. DAZ3D’s inhouse materials have always excelled in the specular department - even at the times of the default “DAZ Material”.
I really hate using the default UberSurface for skin, because I’m no specmapping wizard. I prefer subtle-yet-important simplicity that working fresnel attenuation of specular provides. //and yeah, I suggest a different workflow for US2 that does not formally respect energy conservation parameter-wise, but that’s a whole ‘nother discussion//
Here’s a couple of my relatively recent renders that use US2 and oldschool maps: not that they “show a lot of skin” (I don’t do that!), but, like, a litmus test. If you go “whoah, that’s horrible”, then just block my posts and forget everything I ever wrote.
- a more realistic one (‘cause the textures are realistic) http://www.daz3d.com/forums/viewthread/14967/P105/#253653
- a more stylised doll-like one (‘cause, well, The Girl’s textures are painted) http://www.daz3d.com/forums/viewthread/14967/P150/#259648
I use UE2 set to AO+soft shadows with maps either made in Bryce or converted from Openfootage.net, and a single distant light (raytraced shadows on these ‘cause it’s a “shader” light from the SDK and it’s fast enough for them)
...other points gleamed from the thread that I’d like to comment on:
a) Now, blue specular. It’s a GOOD THING.
Skin is dielectric (that’s why it scatters and fresnels an’stuff). For dielectrics, real specular is white. BUT:
“In order to get a good non-metallic result (neutral specular color), we need to neutralize the specular reflection using the inverse color of the diffuse… Because, in RGB, whites and grays contain all colors. Since they have all colors, they will also contain the diffuse color, and once you add this portion of the diffuse color, contained in the grays of the specular, on top of the original diffuse, the result will give the material a metallic aspect”
Source and piccies: http://www.manufato.com/?p=902 - a very useful page overall. Really, read it, folks.
b) Wancow, could you explain the physics-based reasoning behind your decision to use SSS on fabrics?? The way I see it, I don’t believe fabrics truly scatter in the same way solid substances do - they consist of multiple threads discernible with the naked eye. If anything, light PASSES through the fabrics (US has Translucency for that), and tiny fibers scatter surface diffuse light at specific angles (this is what Velvet is really for, it’s not for skin unless it’s a baby covered in downy fuzz or something…). There’s nothing really going BELOW (=sub) the surface of fabrics.
Now leather would scatter classically, but not fabrics…
c) “Enclosing characters into some primitive”? Only necessary if you’re using crazy raytrace distances for your AO or IDL: “crazy” is anything over 25 cm.
Actually I’m using “crazy” not because I’m questioning someone’s intelligence, no - I’m not THAT evil. In my parlance, “crazy” means “adding unnecessary overhead to render time”.
Yet, this time crazy distances are also simply not realistic. Try playing with actual objects IRL and note the distance at which you start noticing the reflected indirect tint.
Crazy distances are only justified if you’re using UE2 in GI BOUNCE mode (when it DOES NOT provide light by itself, only bounces your other lights against surfaces). If you are using UE as an actual source of light, there’s the map doing most of the fake bounce for you.
Now if you’re using raytraced reflections, you definitely need an all-enclosing environment, but a simple primitive’s going to be boring in reflections… at least, stick something large and colourful behind your camera.
d) UE2 and point-cloud occlusion. If you actually read the docs for 4.5 (those lists of “new features” or something, that’s where it was), you’d see that UE2 is now designed to TAKE ADVANTAGE of point-cloud. Drop it in and set it to AO with soft shadows. If you set it to “ambient only”, it will wash out a lot of your point-based occlusion, BTW. And setting up a thousand oldschool lights to simulate envlighting… good grief, that’s crazy. As in, unnecessary wasting of render resources.
Lower the occlusion distance in the scripted renderer settings, as well.
Alright folks, I have a big headache, so I’m really really sorry if I sound offensive or something. It’s not intentional. Just try thinking in a foreign language when your brain won’t cooperate with the simplest tasks… it’s no fun =(((