【作者】 神和龙；

【导师】 尹勇；

【作者基本信息】 大连海事大学 ， 交通信息工程及控制， 2011， 博士

【摘要】 海上搜救模拟器的环境真实感很大程度上取决于视景系统的好坏,在视景系统中增加因各种自然现象而产生的特殊效果可大大增强系统的真实感。本文在分析了当前模拟器视景系统的国内外研究现状后,提出了多种急需增加的视景特效建模与真实感绘制方法,并予以实现。为逼真地模拟随天气、时间变化的天空背景、云层等,本文对大气散射模型进行研究,建立了一种适用于海上搜救模拟器视景系统的预计算大气散射模型,并将预计算结果以合适的索引预存为三维查找纹理,以便在各种光影效果绘制时实时查询。基于GPU实现的Perlin噪声和改进的细胞自动机模型进行了云景的建模与真实感绘制,对预计算散射纹理采样进行光影计算；通过三维云绘制实现了逼真的云与搜救直升机交互特效,并基于绘制到纹理技术和航迹推算法进行加速。基于GPU实现的后期处理算法完成了体积光、闪电和彩虹等视景特效及夜视场景的真实感绘制,在尽量不影响系统性能的前提下实现了各种视景特效的逼真模拟。基于扰动源高度场叠加的方法实现了Kelvin船艏波的建模与绘制,建立船艏波形高度场,并实现与海面高度场的无缝结合。改进了SPH的近邻粒子搜索方法,并在其流体方程中引入矢量涡度项,基于CUDA(Compute Unified Device Architecture,统一计算设备架构)进行Navier-Stokes方程的求解,实现了具有局部涡流效果的船舶尾迹流建模与真实感绘制。虽然各种视景特效的仿真思路不同,但无论是基于物理还是基于过程的模型均是着眼于保证系统运行实时性前提下的真实感绘制。本文充分利用GPU强大的并行处理性能和可编程能力来提高算法的运行速度,并把所提出的以上各种视景特效绘制方法在当前搜救模拟器视景系统中测试应用。通过各个试验场景绘制截图和性能数据分析可以看出,基于本文算法绘制的各种视景特效真实感强,效果逼真,具有较高的绘制效率,适用于海上搜救模拟器的视景系统。更多还原

【Abstract】 Operating environment realism of Marine Search and Rescue Simulator (shorted for MSARS) mainly lies on the realistic visual system. Rendering various special effects caused by different natural phenomenon will improve system realism greatly. After analysis of current situation of MSARS visual system, modeling method and realistic rendering technology of various special effects are presented and implemented in this thesis.In order to render the change of sky scene and cloud etc. under different weather and time condition, a precomputed atmospheric scattering model which is accurate and suitable for MSARS visual system is presented. This model both takes into account Rayleigh scattering and Mie scattering. A 3D look-up texture is established to store the precomputed results based appropriate indices, which can be used to query in real-time for light rendering. Based on Perlin noise model implemented on GPU and improved Cellular Automata method, a cloud scene mixed with 2D and 3D cloud is modeled and rendered realistically. Cloud lights are rendered by precomputed scattering texture. Realistic interaction between 3D cloud and helicopter is realized. Render To Texture (RTT) technology and Dead Reckoning method are used to accelerate rendering speed of 3D cloud. Some special effects such as volumetric light, lightning, rainbow and night vision scene are rendered realistically and efficiently with different post process methods on GPU. Kelvin ship bow wave is modeled and rendered by adding disturbance sources height map. The bow wave heightmap is spliced seamlessly with current sea surface and gets a realistically rendering result. After improving the neighbor particles search method, vorticity confinement is introduced into the Smooth Particle Hydrodynamics (SPH) fluid equation to simulate rotational flow. The Navier-Stokes fluid equation is solved by CUDA efficiently. Based on this model, ship wake with partial vortex flow is implemented realistically.All these special effects rendering methods are implemented based on different modeling approach. Either the physical model or procedural model is on the premise of real-time rendering. The efficient parallel calculation and programmable property of GPU are used to acquire a higher performance of presented method. All the rendering methods presented are applied in the visual system of MSARS for testing. Captures of rendered scene and final data of performance test show that these methods, which can provide realistic rendering results and efficient rendering performance, are very suitable for visual system of MSARS.更多还原