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题名	基于植物模型处理的森林景观实时绘制
作者	邓擎琼
学位类别	工学博士
答辩日期	2008-05-30
授予单位	中国科学院研究生院
授予地点	中国科学院自动化研究所
导师	胡包钢 ; 张晓鹏
关键词	计算机图形学 实时绘制 植物场景 叶片 细节层次模型 computer graphics real-time rendering outdoor scene foliage level-of-detail
其他题名	Real-time Rendering of Forest Scenes with Plant Model Processing
学位专业	计算机应用技术
中文摘要	植物场景的实时并且高真实感绘制一直是计算机图形学的一个重要目标。但植物通常具有复杂的拓扑形态和丰富的几何细节，使得植物场景的实时绘制至今仍是一个挑战。 本文采用层次细节技术，建立树冠部分的多分辨率模型。最终对数万棵树木组成的森林实现了实时漫游。 本文的主要研究工作和贡献包括以下6个方面： 1. 提出了通用的树叶简化算法，适用于具有任何形状的树叶。从而克服了现有算法只能简化四边形或三角形形状树叶的缺陷。 2. 提出了三种方法对树叶简化过程进行加速，以提高简化效率，减少预处理时间。实验表明，对于含有巨量树叶的树木，使用本文方法预处理时间只有几秒，而已有方法至少需要几十个小时。 3. 提出了三种方法对树叶绘制过程进行加速，提高了绘制速度，使得绘制一棵树所需的时间从传统的几秒甚至几百秒缩短到了几十微秒。并且树的枝叶越茂森，本文方法的速度优势越明显。 4. 对针叶冠层提出了基于多分辨率圆柱模型（或者多边形模型）和半透明线模型的层次细节构造方法。 5. 提出了一种新的分级广告牌模型算法。该算法根据树枝的拓扑信息建立各级子树的纹理图像，并利用树木的自相似性减少所需纹理图像的数目。 6. 采用分级结构管理植物场景，加速了场景的绘制。
英文摘要	Model processing and real-time and realistic rendering of plant scenes is a key task in computer graphics. However, plants, especially trees, contain rich geometric details and topological structure information. As a result, fast rendering of outdoor scenes becomes a big challenge. This thesis uses the technique of Level-Of-Detail (LOD). By constructing continues multiresolution models for foliage, we allow rendering hundreds of thousands of trees in real time. The main contributions of this thesis include following six issues: 1. Unlike other existing methods simplifying quadrangle leaves or triangle leaves only, our method can be used to deal with most species of leaves, which may be represented by complex mesh models. 2. We propose three methods to accelerate foliage simplification, so that the speed of our simplification algorithm is drastically improved, resulting in a high efficient preprocessing. We can simplify a tree with huge number of leaves in a few seconds. However, if use other foliage simplification methods, it may take several hours, even days. 3. We propose three methods to accelerate foliage rendering. Compared with existing method, we can render foliage of a big tree in just tens of microseconds, gaining a speedup of at least 100 times. 4. We present an approach to construct continuous LOD models for coniferous foliage geometry. The models are defined with multiresolution cylinders and semi-transparent lines. 5. We propose an improved billboard clouds algorithm for interactive visualization of functional structural plant models. In our approach, a hierarchical structure of billboards is generated respecting to the plant topology, and the characteristic of self-similarity of plants is applied to reduce the memory cost for textures. 6. We use hierarchical structure to organize scenes. Such structure allows fast View-frustum culling, resulting in high frame rates in rendering.
语种	中文
其他标识符	200518014628038
内容类型	学位论文
源URL	[http://ir.ia.ac.cn/handle/173211/6096]
专题	毕业生_博士学位论文
推荐引用方式 GB/T 7714	邓擎琼. 基于植物模型处理的森林景观实时绘制[D]. 中国科学院自动化研究所. 中国科学院研究生院. 2008.

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