海浪建模与绘制的关键技术研究

发布时间：2018-11-17 12:35

【摘要】：虚拟现实场景的仿真是虚拟现实领域的基础工作。海浪场景是虚拟现实场景中较为复杂的场景之一。首先,海浪的形状复杂,不能由简单几何体构造,在使用基本几何图元构造时需要大量的数据。其次,海浪是动态变化的,每一次变化都要求计算机重新进行一次绘制。再次,海浪的形成受多种因素的影响,波形的变化规律多种多样,海浪的形态在不同的时刻具有随机性。最后,海洋环境多样,天气多变,环境光源需要考虑各种法线的反射与折射。海浪最终颜色不宜确定。如果光照不能处理好,将极大影响海浪模拟的真实性。正是由于海浪场景的复杂,海浪的建模与绘制存在许多难点。本文分别对海浪场景的建模与绘制技术进行分析与研究。首先,针对海浪谱方法在建模时存在的周期性重复现象及真实感不强的问题,本文提出基于扰动的海浪谱建模方法。为了在海浪谱上叠加柏林噪音扰动,给出依据视点位置的叠加策略。当视景体中出现较大面积海面时,依据本文给出的叠加公式,将柏林噪音与海浪谱生成的高度图进行叠加,使得相应海面的高度图发生变化,进而减弱周期性重复现象并提高海面真实感。其次,针对光线跟踪算法在动态海浪绘制时帧率较低的问题,本文从海浪场景三角形分布不均匀的特点出发,提出适宜于海浪场景的基于简单光照的光线跟踪算法及其加速结构。光线跟踪算法的光线跟踪策略要依据光照模型,海浪场景中全局光照模型的光线跟踪策略有许多的跟踪是不必要的,因此,提出简化折射与限制反射光线条数的简单光照模型。海浪场景中对象大多分布在海面高度一定正负范围内,在加速结构建立时,相当多的时间消耗在了海面上部与天空盒之间的空白区域,因此提出多层次的加速结构及选择性更新的策略。最后,分析海面漂浮物漂移过程的风流条件对运动的影响,研究蒙特卡洛方法在漂移模型计算中的应用,基于本文提出的海浪建模与绘制技术,建立一个用于飘移模型的海面三维可视化系统。
[Abstract]:Virtual reality scene simulation is the basic work in the field of virtual reality. Wave scene is one of the more complex scenes in virtual reality. First of all, the shape of waves is complex and can not be constructed by simple geometry, and a lot of data are needed when constructing with basic geometric graph elements. Secondly, the waves are dynamic, each change requires a computer to redraw. Thirdly, the formation of waves is influenced by many factors, the variation of wave waves is varied, and the shape of waves is random at different times. Finally, the marine environment is diverse and the weather is changeable, so the reflection and refraction of various normal lines should be considered. The final color of the waves is not certain. If the illumination can not be handled well, it will greatly affect the authenticity of wave simulation. Because of the complexity of wave scene, there are many difficulties in ocean wave modeling and rendering. In this paper, the modeling and rendering techniques of ocean wave scene are analyzed and studied. Firstly, in order to solve the problem of periodic repetition and lack of reality in wave spectrum modeling, a wave spectrum modeling method based on disturbance is proposed in this paper. In order to superimpose Berlin noise disturbance on wave spectrum, a superposition strategy based on viewpoint position is proposed. When a large area of sea surface appears in the visual object, according to the superposition formula given in this paper, the height map generated by the Berlin noise and the wave spectrum is superimposed to make the corresponding sea surface height map change. Then the periodic repetition phenomenon is weakened and the sea surface reality is improved. Secondly, aiming at the problem of low frame rate of ray-tracing algorithm in dynamic ocean wave rendering, this paper starts from the characteristics of uneven triangular distribution of ocean wave scene. A ray-tracking algorithm based on simple illumination and its acceleration structure are proposed for ocean wave scene. The ray-tracking strategy of the ray-tracking algorithm is based on the illumination model, and many of the ray-tracking strategies of the global illumination model in the wave scene are unnecessary. Therefore, a simple illumination model which simplifies refraction and limits the number of reflected light lines is proposed. Most of the objects in the ocean wave scene are distributed in the positive and negative range of sea surface height. When the acceleration structure is set up, a considerable amount of time is spent in the blank area between the upper sea surface and the sky box. Therefore, a multi-level accelerating structure and selective updating strategy are proposed. Finally, the effect of wind flow conditions on the motion of floating objects is analyzed, and the application of Monte Carlo method to the calculation of drift model is studied, based on the wave modeling and drawing technology proposed in this paper. A three-dimensional sea surface visualization system for transport model is established.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP391.9

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