三维实时云建模与渲染在工业仿真中的应用

在云建模方面,提出一种基于物理仿真和艺术可控性相结合的方法,利用Navier-Stokes流体动力学公式描述单一云朵的聚散和运动,通过盒子的堆积来描述云朵的初始轮廓,最终在盒子内部按流体动力学规律填充粒子生成三维云模型.为了满足实时性要求,在可编程图形芯片上求解Navier-Stokes等式,以便利用图形芯片的并行处理能力加快求解速度.在云的实时渲染方面,基于太阳光照方向和天气状况提出了一种简单的光照模型,大幅度地提高了云的渲染速度.此外,还提出一种改进的环状Impostor技术来提高大范围云层的渲染速度,并通过Shader编程的方法解决了应用Impostor技术到Alpha融合场景中所出现的问题.基于所描述的理论模型,利用三维图形API开发了一套三维云仿真系统,并广泛应用于各种工业仿真和科技娱乐展示项目中,取得了较好的效果.利用该方法生成的云模型具有真实感强、渲染速度快等特点.

Real-Time Modeling and Rendering of 3D Cloud and Its Application in Industrial Simulations

We put forward a physical simulation based method for cloud modeling which is artistically controllable. The cloud formation, dissipation and motion are modeled by physical equations of fluid flow, the Navier-Stokes equations, and the shape of cloud is generated by box accumulation, and finally 3D cloud model is generated through particles filling up. To meet the needs of real-time rendering, the Navier-Stokes equations are solved on GPU, in taking advantages of its parallelism. Regarding to the cloud rendering, a simple cloud lighting model is applied with illumination of sun shine and weather condition. In addition, we utilize the loop impostor technology to improve the rendering speed and solve the problem of applying impostor technology to alpha blended scene by GPU programming. We developed a 3D cloud simulation system by means of graphics API according to the method described in the paper. The system has been applied to various industrial simulation projects and achieved good results. The clouds generated by the method are realistic.