基于IFS的树木摇曳的动态模拟方法研究

发布时间：2018-03-01 19:36

本文关键词： 迭代函数系统高斯函数柏林噪声风场树木　出处：《西北农林科技大学》2013年硕士论文　论文类型：学位论文

【摘要】：随着计算机性能的提高和计算机图形学的发展，虚拟植物的研究尤其是自然景物的建模已经应用到许多领域，如：游戏产业、动漫和广告领域等。分形理论是以植物局部与整体自相似性特征为基础，在局部特征的基础上，根据相关的仿射变换函数，通过计算机强大的迭代能力，对植物整体进行模型的建模。随着计算机仿真技术的发展，植物形态的静态模拟已不能满足现实应用的要求，对植物受自然界外力影响而摆动的模拟成为新的研究热点。树木的动态模拟越来越受到人们的重视和研究。本文在虚拟数学风场中，对分形树木随风摇曳的动态模拟进行了研究。（1）分析和比较已有建模方法的优缺点，提出了基于高斯（Gauss）噪声因子的迭代函数系统（Iterative Function System，IFS）建模方法。通过在树枝和树叶旋转角度的属性中，加入由Gauss函数产生的随机值，随机化树木模型形态，提高树木的自然表现。对构建的树木模型进行纹理映射和渲染，并通过Alpha测试，增强树木的真实性和逼真度。（2）实现了在线性风场模型基础上，加入柏林噪声（Perlin）随机值的虚拟风场的建模方法。在虚拟数学风场中，应用动力学知识，对树枝进行受力分析，得到单节树枝的偏移形态，进而模拟整段树枝在风场中旋转的效果；并对树叶进行受力分析，模拟树叶绕三维坐标系的坐标轴偏转的运动，，得到树叶在风场中摇曳的效果，从而模拟完整树木模型在风场中摇曳的效果。（3）通过加入三维地形、天空、音效等模块，构建虚拟场景，完成三维场景的渲染，并通过雾效处理，增强虚拟场景的真实性，提高树木在风场中随风摇曳的逼真性。本课题以VC++6.0和OpenGL开放图形库为开发工具，实现了树木随风摇曳的模拟方法。该方法能够较真实、自然地呈现树木三维形态特征，并可以逼真的模拟出树木在不同风力大小下的随风摇曳运动。实验表明了该方法的有效性，能形象的模拟树木随风摇曳的效果。
[Abstract]:With the improvement of computer performance and the development of computer graphics, the research of virtual plants, especially the modeling of natural scenery, has been applied to many fields, such as the game industry, Fractal theory is based on the characteristics of local and global self-similarity of plants, on the basis of local features, according to the relevant affine transformation function, through the powerful iterative ability of computer. With the development of computer simulation technology, the static simulation of plant morphology can not meet the requirements of practical application. The simulation of plants swinging under the influence of natural forces has become a new research hotspot. People pay more and more attention to the dynamic simulation of trees. The dynamic simulation of fractal trees swaying with wind is studied. 1) after analyzing and comparing the advantages and disadvantages of the existing modeling methods, an iterative Function system (IFS) modeling method based on Gao Si's Gaussian noise factor is proposed. The random values generated by the Gauss function are added to the attributes of the rotation angle of branches and leaves. The texture mapping and rendering of the constructed tree model were carried out to enhance the authenticity and fidelity of the tree by Alpha test. Based on the linear wind field model, the modeling method of virtual wind field with random values of Berlin noise (Perlin) is realized. In the virtual mathematical wind field, the dynamic knowledge is applied to analyze the force on the branch, and the migration form of the branch is obtained. Then the effect of the whole branch rotating in the wind field is simulated, and the force on the leaves is analyzed to simulate the deflection of the leaves around the coordinate axis of the three dimensional coordinate system, and the effect of leaf swaying in the wind field is obtained. Thus the effect of the complete tree model swaying in the wind field is simulated. The virtual scene is constructed by adding 3D terrain, sky, sound effect modules, and the rendering of 3D scene is completed. The authenticity of virtual scene is enhanced through fog effect processing, and the lifelike of trees swaying with the wind in wind field is improved. With VC 6.0 and OpenGL open graphics library as the development tool, the simulation method of trees swaying with the wind is realized in this paper. This method can present the 3D morphological features of trees naturally and realistically. The results show that the method is effective and can simulate the effect of trees swaying with the wind vividly.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP391.9

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