Overview

The HumanSkin shader is a specialized shader for rendering skin surfaces as skin shading cannot be accurately reproduced using regular lighting models.

HumanSkin Shader Params

Basic information and limitations

• The new shader uses screen-space SSS by default. The old wrap method has been deprecated (doesn't work with deferred lighting).
  • Multilayer option has been modified to accommodate this change.
• Self shadowing has been removed due to artist feedback.
• Due to current hardware limitations, the subsurface scattering has a limited number of samples and thus will create artifacts with high scattering values.
  • There is unfortunately no way around this issue aside from tweaking light conditions to hide the artifacts, or avoid using high scattering values.
  • The best practice is to hover around the default value and ensure that your character never gets too close to the screen.
• There is no translucency in thin areas such as the nose or ears because of deferred lighting limitations.

Using the HumanSkin shader

Subsurface Scattering

Skin's main look is the result of subsurface scattering (light bouncing inside the surface, exiting in a different location than where it entered). Without subsurface scattering skin appears hard like concrete. It's the most important visual cue for the look of skin, therefore great care has been taken into faithfully simulating the effect. See Subsurface Scattering for more detail.

Scattering Radius

Defines the radius of scattering light inside the surface. The lower the value, the less scattering occurs and the more "concrete" the surface looks. Higher values provide a larger sense of translucency but too high can make the surface look like Wax or cause artifacts (this is because of a limited number of samples due to hardware constraints).

Rim Lighting

Rim Lighting simulates light reflection at sharp angles, meaning that it enhances visualization of silhouette shapes, separating surface (making it more visible) from the background. See Rim Lighting for more detail.

Rim Multiplier

Sets rim lighting intensity/multiplier. Note that rim lighting on brighter skins tones should be very subtle and more visible on darker tones.

Oil specular

Oil specular simulates the specularity caused by a thin layer of oil over the skin.

Oil Spec Glossiness

Glossiness/sharpness of the oil specular highlight. Higher values give a more wet look but too high can break the effect.

Oil Spec Multiplier

Controls the intensity of the oil specular highlight.

Glossiness

Glossiness

Is controllable via a gloss map stored in the specular map alpha channel. It is highly recommended that all major characters have a gloss map (at least for their face) as it gives variation to the specularity of the skin.

Decal overlay

Textures placed in the Decal texture slot will be overlayed over the diffuse texture. For example, this can be used for war camouflage for soldiers, dirt, fake shadows or ambient occlusion.

Multilayer

This option allows two textures to be blended together. In this particular example we used it to simulate the jelly-like flesh of these aliens in Crysis 3. The secondary texture (the inner layer) needs to be plugged into the Opacity texture slot in order for this feature to work. There are also parameters to animate the inner layer texture but those are very straight forward and require no extra setup.

Outer Layer Opacity

Inner Layer Depth

Baked Translucency

This option simulates light absorption (sub-surface scattering) when multilayer is enabled. Channels will open up for SubSurface and Custom texture slots. SubSurface is the channel which allows you to define a custom emission map (if you do not want one a simple grey or white texture can be used) and the Custom texture slot allows you to define your own translucency map.

Translucency Emissive

Translucency Strength

Translucency Surface Reflex