【作者】 陈俊；

【导师】 杨克俭；

【作者基本信息】 武汉理工大学 ， 计算机应用技术， 2011， 博士

【摘要】 海浪场景的仿真一直是计算机图形学研究领域的一个热点,它被广泛的应用于军事模拟、工程计算和艺术创作等领域。随着计算机硬件和软件技术的迅速发展,应用领域对海浪仿真的物理真实性、运行时效性和细节精致性提出了更高的要求。本文从海浪建模方法和GPU绘制技术入手,分析当前研究的现状,对近海海浪造型、表现海浪破碎的粒子系统、海面与海岸生成等内容展开研究,采用GPU技术提高仿真的实效性,实现真实感强、实时性好的近海海浪可视化场景。与以往远海无限海域研究相比,本文面向近海有限海域,考虑了更为复杂的影响和控制因素,使得海浪的仿真过程更加真实准确,渲染造型更加丰富多样。本文所做主要工作和创新点如下：1.针对近海海浪的形态特性,讨论了孤立波理论在计算机仿真中的造型方法,基于近海变形物理模型分析了近海海浪破碎的产生过程以及控制方法,为真实表现海浪破碎的形态,提出了基于孤立波波面检测并生成破碎曲面的构造方法,实现海浪在近海区域破碎的可视化仿真过程。2.充分利用粒子系统的高表现力实现对近海波浪破碎的模拟。分析了海浪的破碎形态并进行粒子造型的分类。为解决粒子数量对模拟波浪破碎实时性的影响,提出了一种基于密度检测的聚合细分粒子动态优化方案,该方案既能使计算和渲染的开销得到优化,又能实现粒子系统对波浪破碎特征的高细节渲染。利用GPU的并行处理能力计算和管理粒子在仿真中的运动状态,实现了卷波喷雾和激散流粒子系统在海浪破碎仿真中的应用。3.为实现海浪真实感的交互,着重分析了适合海浪仿真应用的SPH离散化数值方法,讨论了在SPH应用中最近相邻粒子搜索、边界条件处理以及加速度计算等细节问题,采用一种符合流体控制方程描述的流体运动状态SPH计算方法,实现了与障碍物交互的流体仿真场景实例。4.着重分析了Perlin噪声和FFT算法在生成海面高度场中的应用方法。采用以风为驱动力的FFT模型生成高度场,并提出了基于GPU纹理映射的计算方法。对海面的反射、折射和焦散等光学效果进行分析,提出了实时计算太阳位置的动态光照模型,并采用基于视点投影网格的LOD方法裁剪海面,降低网格计算量和渲染量,最后充分利用GPU可编程能力实现了近海海岸的仿真场景。5.为满足用户地形风格设计和地形建模控制的需求,提出了一种基于草图路径创建海岸地形的方法。设计了生成地形高度场过程中涉及的海岸边界弯曲策略、高度图样本匹配、置换与合成策略,采用以高度作为检索条件的纹理匹配和混合方法,实现了基于用户设计草图真实感较强的海岸地形场景。更多还原

【Abstract】 The simulation of ocean scene is a hotpot of the computer graphic research field; it has been widely used in military simulation, engineering computing and arts. With the rapid development of computer hardware and software technology, the application field has required more for physical authenticity, real-time running and detail delicacy of ocean simulation. This thesis indicates with ocean modeling method and GPU rendering technology, analyses the current situation and research on the model of shallow water waves, the particle system which shows the breaking waves and the generation of ocean surface and coast. It uses the GPU technology to improve the efficiency, which implements a better real-time shallow water wave in visual scene. Comparing with previous research which the infinite deep waters, this thesis’s goal is to the finite shallow waters, takes into account more complex factors that influence and control, makes the simulation of waves more realistic and accurate, and obtains rendering and modeling more diverse. The main contents of this thesis are as follows:1. Focusing on the morphological characteristics of shallow water, it discusses the theory of solitary waves’ model method in computer simulation, and analyzes the procedure and control method of breaking wave in shallow water which based on shallow water transform physical model. It has proposed the construct method based on wave surface detection of solitary waves and generating breaking surface to display the form of breaking waves and implement the visual simulation procedure of wave breaking in shallow water field.2. This article has made the particle system to implement the simulation of breaking wave in shallow water. It analyzes the breaking form of ocean wave and classifies the particle form, In order to solve the influence of the particle’s number to the real-time of simulate breaking wave, this article proposes a polymerization and splits particle dynamic optimized rendering based on density detective. This scheme can not only optimize the cost of computer and render, but also implement the high detail render of breaking wave character by particle system. This thesis has made the benefit of GPU to parallel process compute and manage the particle’s movement in simulations, which implements the application of lip spray and whitewater particle system in ocean breaking wave simulation.3. In order to achieve the ocean wave real interaction, this thesis analyzes the SPH simulation applications for wave discretization method and discussed the details of the SPH for particles search in nearest neighbor, the treatment of boundary conditions and the acceleration calculation, using a Navier-Stokes equations describe the fluid movement SPH calculation methods, implementing the interaction with the barrier fluid simulation scenario instance.4. This article analysis the application method of Perlin noice and FFT method in generate height field of ocean surface. The thesis use FFT model motivated by wind to generate height field, and proposes the calculate method based on GPU texture mapping. The thesis analyzes the optical effect of ocean surface’s reflection, refraction and caustics, proposes the dynamic sunshine model of calculating sun’s position, and uses LOD method to clipping ocean surface based on perspective projection grid which results in lower grid calculating and rendering. At last, GPU programming ability is used to achieve the simulation scene of coast in shallow water.5. In order to meet the user needs of terrain style and modeling control, a sketch based on path way is proposed to create coastal landform. It designs a strategy during the generation of the terrain height field bending involved in the coastal border, using the sample matches the height map displacement and synthesis strategies, and search criteria to a high degree of texture as a combination of matching, and implements strong user-based design sketches realistic coastal topography scene.更多还原