Indirect illumination with efficient monte carlo integration and denoising
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Indirect illumination with efficient monte carlo integration and denoising Bo Zhang1
· Kyoungsu Oh1
Received: 18 November 2019 / Revised: 1 September 2020 / Accepted: 16 September 2020 / © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Herein, an interactive, one-bounce, and indirect illumination algorithm that considers indirect visibility even in a fully dynamic scene is introduced. First, a small number of rays are randomly emitted on the hemisphere of the current pixel to obtain the first intersection point in a scene. If this point is directly illuminated by the light source, its illuminated color is collected by sampling the reflective shadow maps for gathering the indirect illumination. Second, to approximate indirect visibility, a three-dimensional ray marching algorithm (MRM) is used; the algorithm is based on a mipmap hierarchy structure generated by voxelizing the scene to accelerate the ray–voxel intersection. Third, images of indirect illumination are denoised by iterating an improved edge-avoiding filtering via a local means replacement method (LMR). Finally, variance-clip temporal filtering on the merged global illumination image is applied to further eliminate jitter. The implementation demonstrates that the algorithm used in this study can efficiently generate high-quality global illumination images. Keywords Real-time rendering · Indirect illumination · Indirect visibility · Ray marching · 3D mipmap · Interactive denoising
1 Introduction Indirect illumination is generated by radiance that has undergone one or more reflections before illuminating a surface point. This significantly affects the realism of the final rendering of images [31]. Recently, global illumination (GI ) has become a standard technique in film and animation industries, and it is often solved offline by ray or path tracers [2]. However, in real-time rendering, such as computer games, high-quality GI is not common [3]. Bo Zhang
[email protected] Kyoungsu Oh [email protected] 1
Department of Media, Soongsil University, Dongjak-gu, South Korea
Multimedia Tools and Applications
In recent years, researchers have addressed GI issues in real time. Dachsbacher and Stamminger [6] rendered a scene from a light source to generate reflective shadow maps (RSMs). Subsequently, the RSMs were used to obtain indirect illumination at the incoming rendering pass. Two shortcomings are associated with RSMs. First, many flux samples are required to obtain a good result. Second, RSMs do not consider indirect visibility, which indicates whether the indirect radiance is blocked by opaque objects [44]. Crassin et al. [5] introduced the voxel cone tracing (V CT ) approach, which organizes voxelized scene via an octree structure and emits several cones on the hemisphere to approximate indirect illumination. VCT exhibits high performance in pure static scenes; however, it cannot manage scenes with a large number of dynamic objects. Although the separate organization of static and dynamic objects can improve th
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