Radiance Cascades

Radiance Cascades is an approach to real-time global illumination, created by Alexander Sannikov at Grinding Gear Games for Path of Exile 2. First presented at ExileCon 2023. It has since been extended and modified in a variety of ways by an active community of developers and researchers.

The core insight — the penumbra hypothesis — is that resolving light from an object requires higher spatial resolution nearby and higher angular resolution far away. RC exploits this inverse relationship: each cascade level doubles the ray count while halving the probe density, and merging reconstructs a full radiance field cheaply.

The technique is geometry-agnostic (constant cost regardless of scene complexity) and produces noiseless results in 2D. Extending RC to 3D remains an open problem — see variants.

2D SRGB Falloff

Additional Controls

Bilinear Fix Disable Mips Non-Linear Accumulation Naive GI Noise Reduce Demand (Calculate over 2 frames) Ringing Fix

Sun Angle

Start Here

1. SimonDev’s video — accessible introduction
2. jason.today — interactive step-by-step walkthrough
3. Fundamentals of RC — clear diagrams
4. The original paper

Browse

• Research: Papers
• Learning: Guides · Talks
• Code: Implementations · Tools
• Techniques: Fixes & Optimizations · Variants
• Language: GLSL · HLSL · WGSL · Rust · C++ · JavaScript · CUDA

Community

• Dedicated RC Discord
• Graphics Programming Discord — RC thread
• radiance-cascades.com — interactive playground with fix toggles

Many fixes and variants on this wiki originated from these communities.

This wiki is easy to contribute to. See How to Contribute.