CAREER: Transient Signal Processing for Realistic Imagery

本研究从信号处理的角度描述了光传输，并将其应用于图像合成和材料外观获取。视觉信号的一个关键方面是它们的频率内容，即光强度是平滑变化还是呈现高频内容和不连续。虽然这些特征被许多技术所隐含地利用，但很少有关于全球照明的正式频率分析的工作。本研究发展了一个理论框架，描述了场景中所有光相互作用在频率特性方面的影响。这一理论也被应用于开发更有效的图像合成算法，以及解决材料属性获取中的逆问题。该研究为现实图形提供了强大的信号处理基础，并使高质量计算机图形图像的创建更快，更容易。本研究为光输运机制建立了一个新的信号处理框架。研究了辐射函数的局部频率内容，重点研究了它如何受到阴影、遮挡和自由空间旅行等现象的影响。这项工作是全面的，因为它处理了辐射域的角度和空间维度，这扩展了以前的工作，通常只处理这些组成部分中的一个。这一理论工作提供了概念上的启发，并为应用提供了分析公式。特别地，开发了实用的光照模拟和实时渲染算法。这些算法利用辐射信号的频率特性知识。加速策略依赖于适当时较低的采样率和由于高频模式造成的感知掩蔽。还开发了新技术来获取真实世界的材料特性，包括获取和表征地面真值数据。这允许验证在其他项目中所做的假设，也可以利用这些特征来更快地获取。

This research characterizes light transport from a signal-processing perspective with applications to image synthesis and material-appearance acquisition. A crucial aspect of visual signals is their frequency content, that is, whether light intensity varies smoothly or presents high-frequency content and discontinuities. While such characteristics are implicitly exploited by a number of techniques, there has been little work on the formal frequency analysis of global lighting. This research develops a theoretical framework that describes the effect of all light interaction in a scene in terms of frequency characteristics. This theory is also applied to develop more efficient image synthesis algorithms, and to solve inverse problems in material-property acquisition. The research provides strong signal-processing fundamentals to realistic graphics and enables faster and easier creation of high-quality computer graphics imagery.This research establishes a novel signal-processing framework for the mechanisms of light transport. The local frequency content of the radiance function is studied with an emphasis on how it is affected by phenomena such as shading, occlusion, and travel in free space. This work is comprehensive in that it treats both the angular and spatial dimensions of the radiance domain, which extends previous work that usually treated only one of these components. This theoretical work serves as conceptual inspiration and provides analytical formulas for applications. In particular, practical algorithms are developed for lighting simulation and real-time rendering. These algorithms exploit knowledge of the frequency characteristics of the radiance signal. The acceleration strategies rely on lower sampling rates when appropriate and perceptual masking due to high-frequency patterns. New techniques are also developed to acquire real-world material properties, including the acquisition and characterization of ground-truth data. This permits the validation of assumptions made in other projects, and also the exploitation of these characteristics for faster acquisition.