Progressive Transient Photon Beams

TL;DR

This paper introduces a novel, consistent, and robust algorithm for transient rendering in participating media, capable of producing complex, time-resolved light transport animations with caustics by extending photon beams to the transient domain.

Contribution

It generalizes photon beams to transient states and develops a progressive spatio-temporal density estimation method with finite memory, improving transient rendering accuracy and efficiency.

Findings

Demonstrates improved transient rendering quality over previous methods.

Provides a convergent algorithm with finite memory requirements.

Achieves realistic animations of complex light paths in participating media.

Abstract

In this work we introduce a novel algorithm for transient rendering in participating media. Our method is consistent, robust, and is able to generate animations of time-resolved light transport featuring complex caustic light paths in media. We base our method on the observation that the spatial continuity provides an increased coverage of the temporal domain, and generalize photon beams to transient-state. We extend the beam steady-state radiance estimates to include the temporal domain. Then, we develop a progressive version of spatio-temporal density estimations, that converges to the correct solution with finite memory requirements by iteratively averaging several realizations of independent renders with a progressively reduced kernel bandwidth. We derive the optimal convergence rates accounting for space and time kernels, and demonstrate our method against previous consistent transient rendering methods for participating media.