ARPΔ : hardware-accelerated ray-traced photon differentials

Abstract

Photon mapping is a widely used rendering technique that provides biased but consistent global illumination through particle and radius-based density estimation. In this work, we enhance photon mapping by integrating photon differentials, representing each photon as a beam connected to its neighbours. Our proposed method, ARPΔ, dynamically adjusts bandwidth by leveraging changes in both the photon’s position and direction, allowing for adaptive control based on the photon’s path through the scene. Additionally, ARPΔ combines multiple photon differential strategies to enable efficient global illumination on ray tracing hardware, seamlessly transitioning to progressive photon mapping in highly anisotropic conditions. Experimental results demonstrate that ARPΔ achieves image quality comparable to state-of-the-art photon mapping techniques, validating its effectiveness in producing high-fidelity renders.