| Title: | 高度复杂场景真实感绘制技术研究 |
| Author: | 陈彦云
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| Issued Date: | 2000
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| Major: | 计算机应用技术
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| Degree Grantor: | 中国科学院软件研究所
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| Place of Degree Grantor: | 中国科学院软件研究所
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| Degree Level: | 博士
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| Keyword: | 真实感绘制技术
; 光线跟踪
; 辐射度技术
; 网格划分
; 纹元
; 体纹理
; 植物场景
|
| Abstract: | 绘制技术是将几何模型转变成我们视觉上清晰直观图像的手段，它的研究内容非常广泛，本文主要集中研究如下三个方面：1. 辐射度技术及其工程应用 辐射度技术是全局光照的主要算法之一。运用这种技术通常需要场景的漫反射和非漫反射光能分布。场景的划分策略是计算漫反射光能分布的重要步骤，而如何将光能和漫反射和非漫反射分量结合起来是辐射度技术应用的另一个重要问题。本文提出一种划分策略，它简单高效，因此非常适合大规模工程应用。在光照计算方面，本文改进了经典的逐步求精算法，使漫反射和非漫反射能量分布能同时得到处理。2. 植物场景的真实感绘制 生成具有高度真实感的植物场景图像是很具挑战性的难题。植物的结构通常都非常复杂，但具有明显的分类特点，因此必须采用不同的构造工具和绘制算法来处理不同类型的植物，这样才能节省存储量和保证绘制率。本文在这方面的工作包括：◆ 拓广了纹元的结构，使之可以用来构造草地和针叶树；◆ 给出了构造草地纹元、松针纹元和远树体纹理的; ◆ 提出了构造草地和森林的简单步骤；◆ 提出了包括结合纹元绘制技术的光线跟踪方法、结合体绘制技术的光线跟踪方法和一种基于 OpenGL 函数的深度缓冲区阴影生成方法等绘制技术，分别用于绘制草地、针叶树、森林和简单阔叶树。3. 长发的绘制 长发图像的生成是计算机图形学最具挑战性的难题之一。我们采用弯曲纹元构造长发束、然后将这些弯曲纹元离散成便于绘制的连接直纹元，并提出一个特殊的绘制算法使得连接的直纹元具有平滑的光照效果，绘制出具有较高真实感的长发图像。 |
| English Abstract: | Rendering technique is a fundamental tool by which the geometric models are transformed into meaningful visual images. This thesis addresses the problem of realistic image synthesis from three aspects. 1. Application of Radiosity Radiosity is one of the major global illumination algorithms. By using the technique we need in general compute the distribution of the diffuse energy and the non-diffuse energy of a scene. Subdivision scheme is the key step for the computation of diffuse energy distribution. And the combination of non-diffuse component and diffuse component is another important problem for applications. This thesis presents a meshing approach that is particularly suitable for large-scale engineering applications due to its high efficiency and ease of implementation. In illumination calculation, progressive refinement algorithm has been extended so that diffuse and non-diffuse energy could be handled in combination. 2. Synthesis of Vegetation Scene Generation of realistic images of vegetation scenes is a challenging problem. The structures of vegetation objects are in general very complex, carrying on various category features. To meet the requirement in both storage and computation, various construction tools and rendering techniques are provided to deal with different vegetation objects. Our approach in this aspect cover several solutions: ◆ The classical structure of texel model is generalized so that this tool can be used to construct and render meadow and conifer. ◆ The generation methods of meadow-texel, conifer-texel and volumetric texture of distant trees are introduced. ◆ Simple construction procedures are provided which can be used to build meadow and forest scenes. ◆ Different rendering algorithms, including the combination of ray-tracing and texel rendering technique, the combination of ray-tracing and volumetric texture rendering method, and a new z-buffer shadow generation method based on OpenGL functions, are proposed to render meadow, conifer, forest and simple broadleaf respectively. 3. Rendering of Long hair The generation of long hair image is one of the most challenging problems in computer graphics. We use curved texels to represent clusters of long hair, and the curved texels are in turn discretized into connected straight texels. Through making smooth effect of connected texels, a special rendering strategy is provided to generate realistic longhair images. |
| Language: | 中文
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| Content Type: | 学位论文
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| URI: | http://ir.iscas.ac.cn/handle/311060/7608
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| Appears in Collections: | 中科院软件所
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| LW002986.pdf（967KB） | -- | -- | 限制开放 | -- | 联系获取全文 |
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| Recommended Citation: | |
陈彦云. 高度复杂场景真实感绘制技术研究[D]. 中国科学院软件研究所. 中国科学院软件研究所. 2000-01-01.
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