Choi, HajinMoon, BochangZhang, Fang-Lue and Eisemann, Elmar and Singh, Karan2021-10-142021-10-1420211467-8659https://doi.org/10.1111/cgf.14406https://diglib.eg.org:443/handle/10.1111/cgf14406Photon mapping is a light transport algorithm that simulates various rendering effects (e.g., caustics) robustly, and its progressive variants, progressive photon mapping (PPM) methods, can produce a biased but consistent rendering output. PPM estimates radiance using a kernel density estimation whose parameters (bandwidths) are adjusted progressively, and this refinement enables to reduce its estimation bias. Nonetheless, many iterations (and thus a large number of photons) are often required until PPM produces nearly converged estimates. This paper proposes a post-reconstruction that improves the performance of PPM by reducing residual errors in PPM estimates. Our key idea is to take multiple PPM estimates with multi-level correlation structures, and fuse the input images using a weight function trained by supervised learning with maintaining the consistency of PPM. We demonstrate that our technique boosts an existing PPM technique for various rendering scenes.Computing methodologiesRay tracing10.1111/cgf.14406121-130