Realistic Computer Graphics for Natural Scenes

自然场景的逼真计算机图形

• 批准号: 9731859
• 负责人: Peter Shirley
• 金额: $ 36.69万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-15 至 2002-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9731859&HistoricalAwards=false
• 关键词: Realistic; Computer; Graphics; Natural; Scenes

This project aims to improve the quality of computer graphic images of outdoor, natural scenes. To date, renderings of outdoor terrain have had a cartoon-like quality that significantly distracts from a sense of realism. Partially, this is due to computational and source data constraints that limit the geometric complexity of terrain that can be rendered. The thesis of the research described here is that illumination and material properties play an equally important role in creating a sense of realism from these scenes. Moreover, there are important interactions between geometry, illumination, and material properties in a model of outdoor terrain that should be understood when real-time constraints must also be satisfied. Significant progress has been made in the last decade in understanding how to generate realistic renderings of indoor scenes. The general approach is to analyze the physics of light transport in such environments and then to embody approximations to the physics in computational algorithms. Correct modeling of illumination and material properties is vital. It is now known that a sense of realism depends critically on accounting for shadows, secondary illumination, and non-uniform reflectance functions. Accurately approximating the effect of these properties involves great computational expense. As a result, methods for rendering realistic imagery almost always exploit assumptions about the nature of the geometric structure and illumination and materials properties likely to be encountered. Most of these assumptions derive from a presumption of indoor environments. Outdoor scenes present very different computational characteristics. While the physics is the same, geometry, illumination, and reflectance properties are all distinctly different. Many of the techniques developed to support realistic rendering of indoor scenes will require substantial modifications for natural, outdoor environments. The most difficult computational prob lem to overcome is the need to be able to aggregate the effects of micro-structures into large enough units that they can be rendered effectively, while at the same time preserving key aspects of visual appearance. This problem exists across a wide range of scales, ranging from foliage, in which a collection of individual leaves generates a collective appearance that is quite different than that of the constituent members, to distant landmarks, where detail must be suppressed without removing those properties that make landmarks distinctive and thus useful.

该项目旨在提高户外自然场景的计算机图形图像的质量。 到目前为止，室外地形的渲染有一个卡通般的质量，显着分散了现实主义的感觉。 这部分是由于计算和源数据约束限制了可以渲染的地形的几何复杂性。 这里描述的研究论文是，照明和材料属性在从这些场景中创建现实感方面发挥着同样重要的作用。 此外，在室外地形模型中，几何形状、照明和材料属性之间存在重要的相互作用，当还必须满足实时约束时，应该理解这些相互作用。 在过去的十年中，在理解如何生成室内场景的真实感渲染方面取得了重大进展。 一般的方法是分析光在这种环境中传输的物理特性，然后在计算算法中体现对物理特性的近似。 照明和材质属性的正确建模至关重要。 现在我们知道，真实感主要取决于对阴影、二次照明和非均匀反射函数的考虑。 精确地近似这些属性的影响涉及巨大的计算费用。 因此，用于渲染逼真图像的方法几乎总是利用关于可能遇到的几何结构和照明以及材料属性的性质的假设。 这些假设大多来自于对室内环境的假设。 室外场景呈现出非常不同的计算特性。 虽然物理性质相同，但几何形状、照明和反射特性都明显不同。 为支持室内场景的真实感渲染而开发的许多技术将需要针对自然的室外环境进行大量修改。 要克服的最困难的计算问题是需要能够将微结构的效果聚合成足够大的单元，以便它们可以有效地渲染，同时保留视觉外观的关键方面。 这个问题存在于广泛的尺度上，从树叶，其中单个叶子的集合产生与组成成员完全不同的集体外观，到远处的地标，其中细节必须被抑制而不去除使地标与众不同并因此有用的那些属性。