复杂条件下真实感树动画模拟方法研究

项目名称： 复杂条件下真实感树动画模拟方法研究

项目编号： No.61303124

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 自动化技术、计算机技术

项目作者： 胡少军

作者单位： 西北农林科技大学

项目金额： 26万元

中文摘要： 复杂条件（如强风和暴风雨等）下树枝的折断、树叶的变形与落叶等现象的真实感模拟是自然现象模拟中的关键问题。本项目从利萨茹曲线、树的植物学特性以及空气动力学等影响树真实感运动的关键性因素出发，结合简化模态分析法和基于视频的方法研究树的运动机制。通过简化模态分析法分析三维空间弯曲悬臂梁的振动模型，结合空气动力学建立阔叶的动力学方程，并采用基于视频的方法提取特定树枝和树叶的自然频率、阻尼系数，首次建立一种视频驱动的树动力学理论模型；针对强风条件下枝叶的折断与落叶现象，提出一种用于判断枝叶折断位置、并能处理折断后树枝几何形状变化及碰撞检测的新方法；运用频谱分析法和基于视频的方法构建风场并模拟落叶现象；结合粒子模型、自由变形等技术，建立风雨条件下雨水与枝叶的交互式模拟新方法；综合运用优化技术加速树的真实感动画模拟，在影视特效、三维动画及虚拟现实等领域具有重要的研究意义和应用价值。

中文关键词： 树；三维建模；动画；视频驱动；风场

英文摘要： It is a challenging problem to animate trees under complex conditions by taking Lissajous curves, aerodynamics, the deformation of leaves and the fracturing of branches into account in the field of natural phenomena simulation. Our project is going to solve the problem mainly by a hybrid method that combining a simplified modal analysis method and a video based method. The project mainly consists of three parts: (1) The first part is the creation of a video driven theoretical basis for realistic tree animation. To achieve this goal, we approximate the forced vibration of three dimensional curved beams by using simplified modal analysis method, and then we consider three dominant modes with slightly different natural frequencies and damping ratios to generate Lissajous curves. For each leaf, we employ a physically-based method to animate its deformation. The dynamics of a tree is created by using the dynamics of branches after carrying out matrix transformation. Aerodynamics model is used to improve the realism of tree animation. The video based method is employed to extract the natural frequencies and damping ratios of branches and leaves; (2) The second part is the animation of the fracture of branches and the falling of leaves in a strong wind field. We first generate a three dimensional wind field based on a

英文关键词： Tree；Modeling；Animation；Video-driven；Wind field