{"title":"Interactive Calculation of Light Refraction and Caustics Using a Graphics Processor","authors":"S. I. Vyatkin, B. S. Dolgovesov","doi":"10.1134/s0361768824010122","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>While modern rendering systems are efficient for modeling complex light paths in complex environments, the rendering of refractive caustics still takes a long time. Caustics are light patterns that occur when light is refracted and reflected from a surface. Due to an irregular density distribution of these specular events, rendering algorithms mainly rely on direct sampling of the bidirectional dispersion distribution function on these surfaces to plot trajectories. This requires a lot of calculations. Photonic maps are also used. However, there are difficulties that limit the applicability of caustic maps. Since each photon in the photon buffer must be processed, one has to choose between a strongly underestimated caustic sampling and a large decrease in speed in order to use a sufficient number of photons for caustics in order to obtain high-quality images. Complex specular interactions cause oversampling in bright focal areas, while other areas of the caustic map remain undersampled and noisy. At the same time, speed takes precedence over realism in most interactive applications. However, the desire to improve the quality of graphics prompted the development of various fast approximations for realistic lighting. This paper presents a combined method for rendering refraction of light and caustics using backward integration for illumination and direct integration for viewing rays. An approach for simultaneous propagation of light and for tracking rays in a volume is used; therefore, it does not require storing data of an intermediate volume of illumination. In the implementation of this method, the distance between the light planes is set to one voxel, which provides at least one sample per voxel for all orientations. The method does not use preliminary calculations, and all rendering parameters can be changed interactively. As a result, using the proposed method, it is possible to create plausible approximations of complex phenomena, such as refractions and caustics. The effect of refraction on the shadow is shown. Complex light patterns occurring due to the curved geometry of objects are demonstrated. The visualization results show the importance of refraction for the appearance of transparent objects, e.g., the effect distortions caused by refraction in the medium and refraction on the interfaces between media. The difference in refractive indices between different media causes a complex interaction between light and shadow areas. It is shown how refraction and caustics improve rendering of functionally defined objects by providing additional information about their shape and location.</p>","PeriodicalId":54555,"journal":{"name":"Programming and Computer Software","volume":"23 1","pages":""},"PeriodicalIF":0.7000,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Programming and Computer Software","FirstCategoryId":"94","ListUrlMain":"https://doi.org/10.1134/s0361768824010122","RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"COMPUTER SCIENCE, SOFTWARE ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract
While modern rendering systems are efficient for modeling complex light paths in complex environments, the rendering of refractive caustics still takes a long time. Caustics are light patterns that occur when light is refracted and reflected from a surface. Due to an irregular density distribution of these specular events, rendering algorithms mainly rely on direct sampling of the bidirectional dispersion distribution function on these surfaces to plot trajectories. This requires a lot of calculations. Photonic maps are also used. However, there are difficulties that limit the applicability of caustic maps. Since each photon in the photon buffer must be processed, one has to choose between a strongly underestimated caustic sampling and a large decrease in speed in order to use a sufficient number of photons for caustics in order to obtain high-quality images. Complex specular interactions cause oversampling in bright focal areas, while other areas of the caustic map remain undersampled and noisy. At the same time, speed takes precedence over realism in most interactive applications. However, the desire to improve the quality of graphics prompted the development of various fast approximations for realistic lighting. This paper presents a combined method for rendering refraction of light and caustics using backward integration for illumination and direct integration for viewing rays. An approach for simultaneous propagation of light and for tracking rays in a volume is used; therefore, it does not require storing data of an intermediate volume of illumination. In the implementation of this method, the distance between the light planes is set to one voxel, which provides at least one sample per voxel for all orientations. The method does not use preliminary calculations, and all rendering parameters can be changed interactively. As a result, using the proposed method, it is possible to create plausible approximations of complex phenomena, such as refractions and caustics. The effect of refraction on the shadow is shown. Complex light patterns occurring due to the curved geometry of objects are demonstrated. The visualization results show the importance of refraction for the appearance of transparent objects, e.g., the effect distortions caused by refraction in the medium and refraction on the interfaces between media. The difference in refractive indices between different media causes a complex interaction between light and shadow areas. It is shown how refraction and caustics improve rendering of functionally defined objects by providing additional information about their shape and location.
期刊介绍：
Programming and Computer Software is a peer reviewed journal devoted to problems in all areas of computer science: operating systems, compiler technology, software engineering, artificial intelligence, etc.
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