The 3Delight Hair shader is a physically plausible shader that renders hair and fur using a Monte-Carlo simulation. A Monte-Carolo simulation explores the different light paths inside a medium (in this case, a clump of hair) to produce an image.
An interestic aspect of hair rendering is that all the intricate visual details seen in hair stem from the scattering of light in a multitude of hair strands and is not due to the complexity of a single hair strand. This seemingly simple observation explains why so many complex shaders are not able to properly relay the feeling of realistic hair. This includes the widely used Marschner shaders.
Example renders of blond, red and dark hair. Note the glow caused by light scattering inside blond and red hair. Also note how black hair has All theses features necessitate proper simulation of light scattering in hair clumps. | |||