Subshading

Subshading refers to a visual technique used in computer graphics and rendering to simulate the scattering of light within semi-transparent objects. Unlike standard diffuse shading, which assumes light reflects entirely off a surface, subshading accounts for light that penetrates the surface, bounces around inside, and exits at a different point. This process creates a softer, more luminous appearance, often seen in materials like skin, wax, jade, or marble.

The effect is particularly noticeable at the edges of objects where light can pass through more easily, causing a glow or translucency. Simulating subshading accurately can be computationally intensive, as it requires tracing light paths within the object. Various algorithms exist to approximate subshading, ranging from simple approximations that add a color tint to edges, to more complex methods that employ photon mapping or volumetric scattering techniques.

The goal of subshading is to enhance realism by capturing the way light interacts with materials that are not perfectly opaque. It helps to differentiate these materials from solid, non-translucent surfaces, contributing to a more believable and visually appealing render. When implemented effectively, subshading can significantly improve the perceived quality and depth of a 3D model.