Scalable Virtual Ray Lights Rendering for Participating Media

Abstract

Virtual ray lights (VRL) are a powerful representation for multiple‐scattered light transport in volumetric participating media. While efficient Monte Carlo estimators can importance sample the contribution of a VRL along an entire sensor subpath, render time still scales linearly in the number of VRLs. We present a new scalable hierarchial VRL method that preferentially samples VRLs according to their image contribution. Similar to Lightcuts‐based approaches, we derive a tight upper bound on the potential contribution of a VRL that is efficient to compute. Our bound takes into account the sampling probability densities used when estimating VRL contribution. Ours is the first such upper bound formulation, leading to an efficient and scalable rendering technique with only a few intuitive user parameters. We benchmark our approach in scenes with many VRLs, demonstrating improved scalability compared to existing state‐of‐the‐art techniques.

Efficient Simulation of Light Scattering Effects in the Atmosphere

“…László et al [14] improved the traditional light-medium interaction model, allowing control of the extinction coefficient and control variables through approximated sampled values, thereby enhancing rendering efficiency. In 2019, Vibert et al [15] presented a new scalable hierarchical VRL method that preferentially samples VRLs according to their image contribution, yet this method requires further improvement for rendering anisotropic media. Deng et al [16] proposed a novel unbiased volume density estimator, the photon surface, which is combined through multiple importance sampling to handle ray paths including single scattering and within-medium transmission.…”