Collaborative Research: Fast and Accurate Volumetric Rendering of Scattering Phenomena in Computer Graphics

协作研究：计算机图形学中散射现象的快速和准确的体积渲染真实世界的场景往往表现出复杂的体积效应，由于粒子介质的光散射。这些效果包括人类已知的一些最壮观的视觉体验，如日出和日落的颜色，辉煌的水下焦散，甚至是由雾、薄雾、雾霾、雨、雪造成的阴沉的天气效果，以及由烟雾和灰尘造成的有害影响。这些效果的逼真视觉再现在各种应用领域具有广泛的影响，包括数字娱乐、科学教育、模拟和训练（飞行、潜水和医疗诊断）以及安全教育（在烟雾和灰尘条件下的水下探索和搜索工作）。虽然在计算机图形学中已经有大量的工作来渲染体积散射的效果，但这些方法通常太慢，无法被广泛采用，需要数小时到数天的时间来模拟一个场景。这使得在视频游戏、交互式照明、虚拟环境或科学教育等应用中包含精确的散射效果变得不可行。本研究的关键观点是，虽然散射的显式数值模拟很困难，但其定性性质非常简单，通常只涉及光的模糊或扩散。调查人员首先确定场景中经常出现的介质和源的简单配置（或几何形状）。接下来，他们根据辐射传输理论，开发出精确的分析和数据驱动模型，描述这些构型中光的多次散射。然后将这些模型与蒙特卡罗、硬件和预计算方法结合起来，在各种动态场景和媒体中以交互速率渲染体积效果。由于分析或算法技术只能与散射特性的基本表示一样准确，因此研究的一个关键部分涉及设计新的实验装置来首次测量广泛的散射介质。最后，这项工作包括一个重要的教育组成部分，促进合作精神，通过新的联合课程，交换学生访问，访问讲座，丰富学生和研究人员的经验。

Collaborative Research: Fast and Accurate Volumetric Rendering ofScattering Phenomena in Computer GraphicsReal world scenes often show complex volumetric effects due to scattering of light by particulate media. These effects include some of the most magnificent visual experiences known to man, such as the colors of sunriseand sunset, the brilliant underwater caustics, or even the gloomy weather effects due to fog, mist, haze, rain, snow, and the hazardous effects due to smoke and dust. Realistic visual reproductions of these effects hasbroad impact in various application domains including digital entertainment, scientific education, simulation and training (flying, diving and medical diagnosis), and safety education (underwater explorations and search efforts in smoky and dusty conditions). While there has been a substantial body of work in computer graphics on rendering the effects of volumetric scattering, those methods are usually too slow to enable widespread adoption, taking hours to days to simulate a single scene. This makes it infeasible to include accurate scattering effects in applications like video games, interactive relighting, virtual environments or scientific education.The key insight in this research is that while the explicit numerical simulation of scattering is difficult, its qualitative properties are quite simple, usually just involving a blurring or spreading out of light.The investigators first identify simple configurations (or geometries) of media and sources which frequently occur in scenes. They next develop accurate analytic and data-driven models that describe multiple scattering of light in these configurations based on the theory of radiative transfer. These models are then leveraged in conjunction with Monte Carlo, hardware and precomputation methods, to render volumetric effects at interactive rates in a wide range of dynamic scenes and media. Since analytic or algorithmic techniques can only be as accurate as the underlying representations of scattering properties, a critical part of the research involves designing novel experimental setups to measure a wide array of scattering media for the first time. Finally, this effort includes a significant educational component and promotes collaborativespirit, with new joint courses, exchange student visits, visiting lectures, enriching the experiences of both students and researchers.