【作者】 吴献；

【导师】 卢德唐； 董兰芳；

【作者基本信息】 中国科学技术大学 ， 计算机应用， 2009， 博士

【摘要】 在计算机图形学领域,早在20世纪80年代就开始了对水波的模拟,然而直到今天,水波动画依然是一项有意义并且具有挑战性的课题。传统的基于过程的方法难以胜任高真实感需求的水波动画模拟,比较而言,基于物理的方法,从运动的本质上研究水波的产生机理,能够产生比较好的模拟效果。然而,物理计算的复杂性往往带来性能上的严重损失,满足不了许多对实时性要求较高的动画应用领域的需要。因此,本文以基于物理的水波实时动画作为研究目标,从水波的造型、控制、绘制及细节上入手,在动画的真实感与效率之间寻求一个良好的平衡,建立了一个能够实现种类丰富且形态逼真的实时水波动画系统.本文的研究工作主要包含了以下几个方面:1.介绍了常用的用于水波动画的物理模型与求解方法,以溃坝动画为例,采用二维浅水方程结合有限体积法的方法,充分利用了GPU(GraphicsProcessing Unit)在数据计算上的并行性,在GPU上实现了实时的溃坝动画。2.基于细胞自动机中邻域传播的思想,提出一种快速的水波模拟算法。采用一种内、外参数分离的控制策略,实时地生成各种水波的参数序列,从而满足了各种不同水波形态的模拟需要。3.针对矩形网格,提出一种视点相关的多层网格划分方法及自适应更新策略,实现了针对大规模区域的水面实时漫游技术。4.采用了基于局部光照模型与动态纹理映射的方法,模拟了在较粗网格下的水波的动态凹凸效果、水面对环境的反射与折射效果、及水底的阳光焦散效果等水波光学特效。在大大增加视觉真实感的同时,实现了水波动画的实时绘制。5.提出了一种基于LOD策略的粒子简化方法与基于纹理的粒子绘制方法,实现了加入水花飞溅效果的溃坝动画与带光、影效果的水面远景瀑布动画.更多还原

【Abstract】 In computer graphics,the simulation of the water began in the eighties of the twentieth century,however,it is still significant and challenging now.The traditional process-based method is hard to be competent for the realistic water simulation,relatively the physics-based method can present realistic water movement better,since considering the inner physics cause of the water movement. However,the complexity of the physical computation often leads to serious performance degradation,and can not meet the real-time needs from various applications.So this paper aims to solve the problem with modeling,controlling, rendering and details by seeking for a tradeoff between the realistic and real-time, and to build a realistic and real-time water animation system with various wave effects.The main work and achievements of the dissertation can be summarized as follows:1.Usual physics-based water animation modeling and numerical algorithms are summarized.An implementation of dam-breaking animation is simulated based on the shallow water equations and a powerful numerical tool named Finite Volume Method.The computation of the modeling is accelerated by taking advantages of the parallelism of GPU(Graphics Processing Unit) based algorithm,and the real-time dam-breaking animation is realized with this accelerated strategy.2.A fast algorithm for water simulation is presented,based on the idea of spread though the neighboring regions in Cellular Automata.A new controlling strategy is used,that the drive parameters of the water movement is taken separately, so it’s easy to change parameters in real time while generating various water waves.3.A view-point-dependent multi-resolution meshing method with a adaptive updating strategy method is proposed.By this method,roaming on a large-scale water area in real-time can be easily realized in our system.4.The local illumination model and dynamic texture mapping method are adopted to simulate some effects,such as bumping waves,reflection,refraction,sun light caustics on water surface constructed by coarse grids.This real-time rendering method can greatly enhance the immersion characteristic of water animation.5.A LOD based particle system is presented to simplify the water particle simulation,and a texture based particle rendering method is proposed to achieve real-time animation.By these methods,we implement two water scenes: dam-breaking flow with splashes and a far view animation of a waterfall with lighting and shadowing effects.更多还原