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基于GPU的实时模拟和绘制中若干问题的研究
其他题名Case Studies on Real-time Simulation and Rendering Methods based on Graphics Hardware
梅星
2008-01-10
学位类型工学博士
中文摘要随着图形业界需求的不断提升和硬件设计制造工艺的发展,现代图形处理器(Graphics Processing Unit,简称GPU) 已经不只是一个单纯处理大量几何面片的3D加速卡,而是具备强大浮点数运算能力,超越多核CPU的并行处理能力和良好可编程能力的高性能处理器。越来越多的研究者开始认识到,灵活运用GPU这些特性可以有效地加速计算、模拟和绘制过程,获得实时的性能效果。另外把数据和相应的计算部分放到GPU上,可以将计算结果直接可视化输出,避免了CPU和GPU间频繁的数据交换,可以极大提高绘制效率。基于这些理由,本文对使用GPU加速实时模拟和绘制中的若干问题进行了研究,主要的工作和贡献有: 1. 提出了一个在GPU上模拟绘制水力侵蚀现象的快速方法。据我们所知,这是首个在GPU上完成此现象模拟的研究工作。以往方法存在着模型不精确,基于CPU的实现性能较低等问题。针对这些问题,我们首先设计了一个新的水力侵蚀模型,根据改进的浅水波方程计算地表流体的速度场,再利用此速度场计算流体对地表的侵蚀作用。此模型改善了模拟效果,提高了计算效率。然后我们将此模型映射为GPU上的多遍绘制过程,加速模型的计算和可视化。实验结果表明此方法能够真实模拟自然界中降雨河流等水体所产生的侵蚀效果,实时处理大尺寸地形上的模拟计算,效率相对于已有方法获得了数十倍的提升。这种高效率的实时模拟方法在地形编辑等领域有很好的应用前景。 2. 提出了一个完全运行在GPU上的水平集方法框架。水平集方法是一种用于追踪动态变化界面的数值方法,在计算机科学领域有着广泛的应用。但是此方法存在两个问题:数值耗散导致计算结果不精确,计算量庞大。我们首先对一种已有的水平集方法做出改进和简化,然后将其并行化,使用GPU来加速水平集的计算。实验结果表明此方法成功减少了数值耗散,提高了水平集方法的准确性,可以实时地计算和绘制大尺寸二维网格和中等尺寸三维网格上的动态水平集,相对于CPU实现,效率提高近二十倍,可较好地用于实时流体模拟和流场的可视化。 3. 提出了一个快速去除体数据中空白空间的预处理方法。在现有的实时体绘制方法中,大量资源被浪费在绘制空白冗余空间上,需要通过预处理方法去除这些空白空间以提升绘制效率。已有一些预处理方法计算较为耗时,去除空白空间的效果不够理想,产生了较多的包围盒而降低优化效果。针对这些问题,我们提出了一种基于kd树结构的预处理方法,逐层去除体数据中的空白空间,绘制剩余有效数据。预处理方法的快速计算依赖于一个求和体积表的建立。实验结果表明此方法预处理时间短,使用很少包围盒就可去除较多空白空间,有效提高了体绘制效率。 总的说来,本文在利用GPU加速模拟和绘制这个课题方向上做出了有益的探索。
英文摘要This thesis aims at exploiting graphics processing units (GPUs) to accelerate real-time simulation and rendering methods. We target the GPU as the basic platform for several reasons. First, aside from their great 3D acceleration abilities, today’s GPUs offer tremendous computational power, high parallelism and flexible programmable ability. More and more researchers are turning to GPUs for better computation and rendering efficiency. Second, mapping the data and its computation kernels onto GPUs would greatly improve the rendering performance, since the updated data in GPU local memory can be directly used for visualization without extensive CPU-GPU data transfer. The main contributions of the thesis include: 1. A new method to simulate the hydraulic erosion phenomenon which runs at interactive rates on GPUs. The method is based on the velocity field of the running water. The velocity field is used to calculate the erosion process. The method has been carefully designed to be implemented totally on GPU, and thus takes full advantage of the parallelism of current graphics hardware. Results demonstrate that the proposed method is effective and efficient. It can create realistic erosion effects by rainfall and river flows, and produce fast simulation results for terrains with large sizes. 2. A fast and accurate level set framework on latest graphics hardware. Level set methods have been extensively used to track the dynamical interfaces between different materials for many scientific and engineering applications. Existing methods usually suffer from two problems: numerical diffusion and expensive computation cost. First, an improved level set method with better accuracy and important simplifications is proposed. Then each step is fully mapped on GPU with an innovative combination of different computation techniques. The proposed method successfully improves the computation accuracy, and provides real-time performance for large size 2D examples and moderate 3D examples. 3 A fast preprocessing method to remove the empty voxels from the volume data for better rendering performance. For most 3D volume data sets, a fraction of the volume is empty, which would bring down the rendering performance. A simple kd-tree based space partitioning scheme is proposed to efficiently remove the empty spaces from the volume data sets at the preprocessing stage. The splitting rule of the scheme is based on a simple yet effective cost function evaluated through a fast approximation of the bounding volume of the non-empty regions. The proposed scheme requires little preprocessing time and improves the rendering performance significantly. As a conclusion, this thesis provides some useful research work on real-time simulation and rendering methods on programmable graphics hardware.
关键词实时模拟和绘制 可编程图形处理器 水力侵蚀 水平集方法 体绘制 Real-time Simulation And Rendering Programmable Graphics Processing Unit Hydraulic Erosion Level Set Volume Rendering
语种中文
文献类型学位论文
条目标识符http://ir.ia.ac.cn/handle/173211/6043
专题毕业生_博士学位论文
推荐引用方式
GB/T 7714
梅星. 基于GPU的实时模拟和绘制中若干问题的研究[D]. 中国科学院自动化研究所. 中国科学院研究生院,2008.
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