Unifying Geometric and Volumetric Light Scattering for Accurate Rendering of Dense Geometry

统一几何和体积光散射以精确渲染密集几何

• 批准号: 0541105
• 负责人: Steve Marschner
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0541105&HistoricalAwards=false
• 关键词: Unifying; Geometric; Volumetric; Light; Scattering

Realistic rendering systems can compute physically accurate images of a wide range of materials. However, some of today's most important challenges in rendering, particularly rendering human beings, involve densely packed elements -- the hairs on a head, the threads in a shirt -- that are readily visible at ordinary distances. Because the geometry is densely packed together, accuracy requires a full simulation of how lightreflects from hair to hair, or from thread to thread, before it gets to the eye. However, these materials are difficult to work with: the parts are too numerous for a detailed simulation to be practical, but they are not small enough to be modeled as a continuous medium. This research is exploring methods that can use both approaches at once without sacrificing accuracy.Correctly rendering these dense aggregations is an important open problem in computer graphics, requiring fundamental theoretical and algorithmic advances to be solved. Directly simulating multiple scattering on such intricate models is prohibitively costly, so in practice it is approximated by simple heuristics. However, for light-colored materials such as blond hair or white cotton, very little light is absorbed in a single interaction, so the visual appearance of these materials is significantly affected by multiple scattering. For correct results a complete scattering simulation is required.This research project aims to efficiently simulate scattering in dense geometry by introducing an approximation of the whole aggregation as a continuous scattering medium. This allows methods for volumetric light transport to be applied when possible while still using the detailed geometry when necessary. Constructing this approximation requires a fundamentally new understanding of the relationship between geometric and volumetric rendering. Implementing the approximation will require new algorithms to be developed, and applying it will require improvements to the state of the art in volumetric rendering.

真实感渲染系统可以计算各种材料的物理精确图像。 然而，当今渲染中的一些最重要的挑战，特别是渲染人类，涉及密集的元素-头上的头发，衬衫中的线-在普通距离下很容易看到。 由于几何体密集地堆积在一起，准确性需要完全模拟光线在到达眼睛之前如何从头发反射到头发，或从线反射到线。 然而，这些材料很难处理：零件太多，无法进行详细的模拟，但它们又不够小，无法作为连续介质进行建模。 这项研究正在探索可以同时使用这两种方法而不牺牲精度的方法。正确绘制这些密集的聚合是计算机图形学中一个重要的开放问题，需要基础理论和算法的进步来解决。 在如此复杂的模型上直接模拟多次散射是非常昂贵的，因此在实践中，它近似于简单的几何学。然而，对于浅色材料，如金色头发或白色棉花，在单次相互作用中几乎没有光被吸收，因此这些材料的视觉外观受到多次散射的显著影响。为了得到正确的结果，需要进行完整的散射模拟。本研究项目旨在通过将整个聚集体近似为连续的散射介质，有效地模拟密集几何结构中的散射。 这允许在可能的情况下应用体积光传输的方法，同时在必要时仍然使用详细的几何形状。构建这种近似需要对几何和体积渲染之间的关系有一个全新的理解。 实现近似将需要开发新的算法，并且应用它将需要改进体绘制的最新技术。