【作者】 蒋燕萍；

【导师】 黄心渊；

【作者基本信息】 北方工业大学 ， 计算机应用技术， 2003， 硕士

【摘要】 在虚拟环境中引入植物生成技术，可把人造环境和自然环境有机地结合起来，塑造出逼真的现实环境。而虚拟环境实时漫游技术则为建筑CAD、环境设计、城市规划提供了方便有利的手段，并为数字城市和虚拟社区提供了良好的解决方案。 本文的主要工作内容集中在以下四方面： 1、研究并改进植物建模算法，生成三维的植物模型 在研究目前植物建模常用算法的基础上，结合迭代函数系统法(IFS)和L系统法提出了树木类植物的随机二叉三维递归模型。该模型中树木的生成与绘制过程可简化为：从根向上画树枝，分为左分枝和右分枝，画树枝的过程可分为若干层，最后一层画树叶。 2、研究并改进虚拟环境漫游算法，加速虚拟环境的漫游 本文通过真实感图形的绘制流程米评价目前虚拟环境漫游常用算法的优劣，提出了相对较新的一种基于几何和图像混合简化方法的实时漫游算法。该算法通过对纹理投影面后的几何插值生成退化几何，实现几何-纹理间的光滑过渡。同时该算法还结合了几何和纹理层次细节的思想。 3、虚拟森林交互设计和漫游系统的设计和实现 利用VRML和VC++开发了虚拟森林交互设计和漫游系统。系统中VRML的应用保证了其在互联网上的实时交互和漫游效果。同时考虑到数据量的大小，该系统采用了用植物图像取代植物模型的思路，以为用户提供更真实的自然景物效果。 4、三维树木交互生成和漫游系统OpenGL Tree的设计和实现 利用OpenGL与C++ Builder的紧密接口，开发了三维树木交互生成和漫游系统OpenGL Tree。该系统用C++语言实现了随机二叉三维递归模型，生成三维树木造型组成自然景物，并应用基于几何和图像的混合漫游加速算法，实现了虚拟环境的交互漫游。 最后对本文所做工作进行了总结，并讨论了今后可能继续的研究方向。更多还原

【Abstract】 Involving the plant generation technology into virtual environment, which may integrate the artificial environment and natural environment, and thus develop a realistic virtual world. At the same time, the technology of real time walkthrough in virtual environment will contribute a lot convenience to CAD in architecture, environment designing, city layout. and provide a good solution for digital city and virtual community.In this thesis, our research work mainly focuses on the following four aspects:1, Studying and perfecting the generation algorithms of plant modeling,building three-dimensional plant modelOn the basis of studying current algorithms of plant modeling, combining Iterated Function System and L-System, we brought forward the random binary three-dimensional recursive model. The generation and render process of the tree could be simplified to: draw the branches from the root, then the branches are split into left branch and right branch. The process of drawing branch would be divided into many steps, we can draw the leaves in the last step.2, Study ing and perfect ing the algorithms of walkthrough in virtual environment, accelerating the walkthrough in virtual environmentIn this paper, we evaluate the advantage and disadvantage of the current algorithms of walkthrough in virtual environment by the rendering process of photorealistic graphics, and then brought forward a new algorithms of real time walkthrough based on the integrated polygon and texture. The algorithms transform polygon and texture into each other, and generate fade polygon by geometrical interpolation in the projection of texture, which would realize smooth transition between polygon and texture. Furthermore, it combine the idea of Level Of Detail of polygon and texture.3. Designing and deveIoping " the Interactive Designing and Walkthrough System of Virtual Forest"Making use of VRML and VC++, we developed an interactive designing and walkthrough system of virtual forest. In the system, the application of VRML assured the real time interaction and walkthrough on the Internet. Considering the data quantity, a thought of replacing the plant model by plant image has been adopted in the system, which may provide more realistic natural scene for the user.4. Designing and developing "the Interactive Generating and Walkthrough System of Three-dimensional Tree" -OpenGL TreeMaking use of the close interface of OpenGL and C++ Builder, we developed an interactive generation and walkthrough system of three-dimensional tree -OpenGL Tree. The system realize the random binary three-dimensional recursive model, and generate three-dimensional tree model to compose natural scene; in addition, it apply the accelerate algorithms based on the integrated polygon and texture, and realize interactive walkthrough in virtual environment.At last, we summarize the work of this thesis and discuss the potential research topics in the future.更多还原