Towards interactive global illumination effects via sequential Monte Carlo adaptation

Journal ArticleThis paper presents a novel method that effectively combines both control variates and importance sampling in a sequential Monte Carlo context while handling general single-bounce global illumination effects. The radiance estimates computed during the rendering process are cached in an adaptive per-pixel structure that defines dynamic predicate functions for both variance reduction techniques and guarantees well-behaved PDFs, yielding continually increasing efficiencies thanks to a marginal computational overhead

A Progressive Algorithm For Three Point Transport

When computing global illumination in environments made up of surfaces with general Bidirectionnal Reflection Distribution Function, a three point formulation of the rendering equation can be used. Brute-force algorithms can lead to a linear system of equations whose matrix is cubic, which is expensive in time and space. The hierarchical approach is more efficient. Aupperle et al. proposed a hierchical three point algorithm to compute global illumination in presence of glossy reflection. We present in this paper some improvements we brought to this method: shooting, "lazy" push-pull, photometric subdivision criterion... Then we will show how our new method takes into account non-planar surfaces in the hierarchical resolution process

Practical Product Path Guiding Using Linearly Transformed Cosines

International audiencePath tracing is now the standard method used to generate realistic imagery in many domains, e.g., film, special effects, architecture etc. Path guiding has recently emerged as a powerful strategy to counter the notoriously long computation times required torender such images. We present a practical path guiding algorithm that performs product sampling, i.e., samples proportionalto the product of the bidirectional scattering distribution function (BSDF) and incoming radiance. We use a spatial-directionalsubdivision to represent incoming radiance, and introduce the use of Linearly Transformed Cosines (LTCs) to represent theBSDF during path guiding, thus enabling efficient product sampling. Despite the computational efficiency of LTCs, several optimizations are needed to make our method cost effective. In particular, we show how we can use vectorization, precomputation,as well as strategies to optimize multiple importance sampling and Russian roulette to improve performance. We evaluate ourmethod on several scenes, demonstrating consistent improvement in efficiency compared to previous work, especially in sceneswith significant glossy inter-reflection