Path Guiding in Production and Recent Advancements

Over the last decade, path guiding algorithms found their way from the scientific realm into production renderers. These algorithms enable the rendering of challenging lighting effects (e.g., complex indirect illumination, caustics, volumetric multi-scattering, and occluded direct illumination from multiple lights), which are crucial for generating high-fidelity images. The fact that these algorithms primarily focus on optimizing local importance sampling decisions makes it possible to integrate them into a path tracer, the de facto standard rendering algorithm used in production today. The theory behind these algorithms has been presented and discussed on various occasions (e.g., in presentations or research papers), and their practical applications in production have been explored in the previous course on: Path Guiding in Production. Nevertheless, the implementation details or challenges associated with integrating them into a production render are usually unknown or not publicly discussed.
This course aims to provide a deeper understanding of how specific guiding algorithms are integrated into and utilized in various production renderers, including Blender's Cycles, Chaos's VRay and Corona, SideFX's Karma, and Disney Animation's Hyperion. The first chapter provides deeper insights into the nitty-gritty details that must be considered when integrating a path-guiding framework into a production renderer, details that are usually unknown. In the second chapter, Disney shares their experiences and challenges when integrating path guiding into their wavefront production renderer Hyperion. The last chapter presents Chaos's recent advancements to their specialized guiding estimator for caustics.