Split Radiance Cascades: Real-Time Global Illumination via Sparse Radiance Probes
2026-07-22 • Graphics
Graphics
AI summaryⓘ
The authors improved a method called Radiance Cascades that helps computers simulate realistic lighting in 3D scenes for games and graphics. Traditional methods either lose detail or are too slow when trying to show light accurately in all directions. They introduced a new approach using a sparse hashmap to store lighting data efficiently in 3D space, along with a technique called ray splitting to better capture how light bounces around. Their method, called Split Radiance Cascades, works well in real-time and produces detailed indirect lighting without noise.
Radiance probeDiffuse global illuminationRadiance CascadesSparse hashmapRay tracingIndirect illumination3D lightingReal-time graphics
Authors
Rouli Freeman, Alexander Sannikov
Abstract
Radiance probe methods are a popular and well-tested approach for approximating diffuse global illumination for real-time graphics, but they commonly suffer from a lack of detail due to the large spacing between probes. Radiance Cascade (RC) fixes this by increasing spatial resolution and reducing angular resolution for light and occlusion from closer objects, which allows it to provide details at all scales without noise or aliasing. However, leading implementations of RC either run in 2D or screenspace, due to the prohibitive costs of storing high-detail volumetric radiance information. In this work, we adapt Radiance Cascades for accurate real-time 3D diffuse global illumination using a sparse hashmap to store world-space probes. We introduce ray splitting, a method for calculating radiance intervals used in RC by tracing rays from visible surfaces and calculating their contribution to cascades based on their hit distance. We evaluate our algorithm, Split Radiance Cascades, on a variety of scenes, and demonstrate that it can provide high-quality indirect illumination in both single-frame and temporally accumulated contexts.