Split-Sum Approximation

Computer Graphics · Real-Time Shading · 2013 · split-sum-approximation.yaml

Factors the specular IBL integral into a prefiltered radiance lookup times a precomputed BRDF response table. Both halves fit in textures, which is what made physically based specular affordable in real time.

• supersedescorrects · extends
• classifiesspecializes · part-of
• substitutes forapproximates · alternative-to
• depends onrequires · validates

Colour is the family; a dashed line is the second member of it.

This node

• approximatesis a cheaper stand-in for Microfacet Modelsplits the integral into two precomputable factors
• requiresdoes not work without Prefiltered Environment Mapone of the two factors is the prefiltered map

References

• Real Shading in Unreal Engine 4 — Karis — 2013
• Background — Image-based lighting on Wikipedia