【作者】 张倚铭；

【导师】 李辉； 邓富松；

【作者基本信息】 四川大学 ， 工程硕士（专业学位）， 2025， 硕士

【摘要】 随着GPU性能的提升与图形学技术的发展,实时且具备高度真实感的烟雾仿真成为飞行视景、影视游戏与战场模拟等领域的关键需求。然而,烟雾流体形态变化多端,光学性质复杂,导致实时渲染计算开销巨大,亟待在效率与细节表现间取得平衡。在实时烟雾仿真渲染的研究中,不同仿真尺度下的烟雾模拟面临着不同方面的几个问题:一方面,在小尺度的动态烟雾模拟方面,当前基于不可压缩的Navier-Stokes(N-S)方程的方法在实时模拟时存在效率不佳,缺少可控细节表现的问题。另一方面,在大规模的全局雾效模拟中,当前基于经验模型的雾效模拟和基于光线步进的体积雾效模拟均存在一定缺陷。前者无法模拟雾效与光线交互产生的光学效应,而后者存在性能不足、雾效层次感明显、体积阴影边界生硬且精确度不足的问题。最后,目前现有的三维战场仿真软件缺乏能在性能和真实感之间平衡的雾效模拟解决方案,这一定程度上影响了仿真的整体真实感和用户的沉浸体验。为了保证可视化平台雾效渲染的实时性和真实感,本文针对以上问题展开了深入的研究,主要的研究工作包括:(1)针对实时烟雾模拟缺少细节表现,实时性较低的问题,提出一个基于GPU并行加速和细节合成技术的实时烟雾模拟算法。该算法在网格上完成烟雾控制方程的并行求解后,基于高频能量场和预计算的湍流函数快速生成具有丰富细节的烟雾。为降低细节速度场对流体整体形态的负面影响,提出了一个合成系数,能够对合成湍流的强度进行自适应控制。完成网格密度数据的更新后,使用优化后的光线步进法对烟雾进行体绘制。实验表明,该算法在保证实时性的同时,显著提升了烟雾流体的真实感。(2)针对当前全局雾效模拟真实感不足的问题,提出一种基于屏幕空间光线步进的体积雾渲染架构。该架构支持多种常见雾效建模,并基于大气散射理论模拟雾中的多种光学现象。为提升渲染效率,对采样点分布进行了优化,并引入随机抖动算法以消除带状伪影。针对体积阴影精度不足、边界生硬的问题,提出一种基于方差的软阴影算法,实现自然的边界过渡;同时结合级联阴影贴图技术,有效缓解阴影锯齿现象。(3)针对当前三维战场仿真系统中物理真实性与交互性雾效缺失的问题,设计并开发了某型三维战场仿真软件。该平台基于实际军事应用场景进行了系统化的需求分析与架构设计,同时将前序研究成果整合成了一个模块化的雾效组件,支持用户以极高的自由度对雾效进行控制。除此之外,该软件还提供了地理信息可视化,武器模型的加载与渲染等功能。更多还原

【Abstract】 With the advancement of GPU performance and graphics technologies,real-time and highly realistic smoke simulation has become a critical requirement in fields such as flight visual systems,film and game production,and battlefield simulation.However,the highly dynamic nature of smoke flow and its complex optical properties pose significant challenges for real-time rendering due to substantial computational costs.There is an urgent need to achieve a balance between computational efficiency and visual detail.In the study of real-time smoke simulation and rendering,different simulation scales present distinct challenges.On one hand,at a small scale,current methods based on the incompressible Navier–Stokes(N-S)equations face issues such as insufficient real-time performance and lack of controllable detail.On the other hand,for large-scale global fog simulation,both empirical models and volume-based ray marching techniques exhibit limitations.The former fails to reproduce optical effects caused by interactions between fog and light,while the latter suffers from performance bottlenecks,overly layered appearance,hard-edged volume shadows,and insufficient rendering accuracy.Furthermore,existing 3D battlefield simulation software lacks fog simulation solutions that effectively balance performance and realism,which to some extent compromises the overall fidelity and user immersion of the simulation.To ensure both real-time performance and visual realism in fog rendering for visualization platforms,this thesis conducts an in-depth study addressing the aforementioned problems.The main contributions are as follows:To address the issues of limited detail and low real-time performance in small-scale smoke simulation,a real-time smoke simulation algorithm based on GPU parallel acceleration and detail synthesis is proposed.After solving the smoke control equations in parallel on a grid,the algorithm rapidly generates rich smoke details using a high-frequency energy field and precomputed turbulence functions.To mitigate the adverse impact of the detail velocity field on the global fluid structure,an adaptive synthesis coefficient is introduced to dynamically control turbulence intensity.Upon updating the grid density data,an optimized ray marching method is applied for volume rendering.Experimental results demonstrate that this method significantly improves the realism of smoke fluids while maintaining real-time performance.To improve the realism of global fog simulation,a volume fog rendering framework based on screen-space ray marching is proposed.This framework supports multiple common fog modeling techniques and simulates various optical phenomena in fog based on atmospheric scattering theory.To enhance rendering efficiency,sampling point distribution is optimized,and a stochastic jittering algorithm is introduced to eliminate banding artifacts.To address the issues of low precision and hard edges in volume shadows,a variance-based soft shadow algorithm is proposed to achieve smooth boundary transitions.Additionally,cascaded shadow maps are employed to effectively reduce shadow aliasing.To resolve the lack of physically realistic and interactive fog effects in current 3D battlefield simulation systems,a prototype 3D battlefield simulation software is designed and developed.The platform is built upon a systematic requirements analysis and architectural design based on real-world military applications.The previously proposed methods are integrated into a modular fog rendering component,providing users with a high degree of control over fog effects.Furthermore,the software supports additional functionalities such as geographic information visualization and weapon model loading and rendering.更多还原