btw, in latest 3dl download, 3.08, point-based color bleeding works with IBL too, with hair as well. A good reason for new tests....
now a shameless plug (but somehow I'm not sure how many SI-community visits the Area too
) - latest image is on Area front page for a while. Back to topic, here's a few more details about hair shading, that I already posted on Area. Really nothing so smart, some images were already posted here, but anyway:
Lighting is a light rig with deep shadow maps. On some places, there's ray-traced ambient occlusion - but hair is excluded from AO.
I intentionally went with as much uniform and simple setup - the goal was to get the same lighting setup for entire character. Dust, background and smoke are separate passes, but character is a just one.
So that's a sunlight with 4096 DSM, back light with 2048, about 20 lights for dome lighting, with 1024 DSM. All lights had enabled both diffuse and specular lighting. I've tweaked shadows to get as much low bias and low smoothing - except back light which has a bit longer bias, in order to get translucency effect. Translucency is not so pronounced here because of type of hairdo, but not big deal to get with more 'spreading' hairdos, like this one
, or this
. I've used only two lights for these two.
Hair shader is a standard, out-of-the-box one, I think it's what is usually called 'shave'. Again, I've been able to go with more advanced shading model as a custom Renderman shader, but I wanted to keep everything as much simple. Some recipe for bright hair is to use colored shadows, a bit darker and more saturated than diffuse color.
I've noticed that hair density has a significant influence, too high density can do a 'melted' shading. So there are a lot of tweaks to avoid this. Let's say, 'clump' effect at the end of hairs isn't an interpolation between guides and hairs, it's a proportional scaling along existing hair shape - as hairs are closer to guides, they are longer. There are five or six mixes between different ways of 'hair grouping', I think. At the end, there is about 30k hairs, all at 0.15 pixel size. By following guidelines from docs, size is the same along hair length - but transparency is varying, from about 0.1 at roots to 0.5 at tips, full transparency just at tips.
There are another small enhancements, for example. specular intensity is randomized along hairs.