Real-Time Screen-Space Subsurface Scattering (SSSS) in Web Graphics
Simulating light transport inside translucent media like skin, marble, jade, and wax using screen-space blur profiles and depth-aware separable kernels.
Standard BRDF models assume light reflects off the exact surface point it hits. Translucent materials absorb and scatter light internally before re-emitting it. Screen-Space Subsurface Scattering (SSSS) approximates this internal light diffusion efficiently across rendered framebuffers.
1. Sum-of-Gaussians Diffusion Profiles
Approximating physical light scattering profiles requires decomposing translucent light transport into a linear combination of separable 1D Gaussian blurs with custom RGB variance weights representing wavelength attenuation.
2. Depth-Aware Separable Screen-Space Blurring
Applying horizontal and vertical blur passes in image space evaluates pixel depth differences from G-Buffers, preventing light from scattering across non-adjacent foreground or background boundaries.
3. Translucency & Back-Lighting Transmission
Combining screen-space front scattering with thickness-map back transmission simulates directional light penetrating thin features like ears, leaves, or thin wax structures in real-time viewports.