真实感海下光照效果实时绘制
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摘要
海洋场景仿真一直是计算机图形学的研究热点.为解决海下光照效果实时模拟问题,提出一种海下光照的模型.首先,以光线追踪理论和比尔朗伯定律为基础,通过求解采样点的亮度值积分和透光比率解决海水与光照交互光束产生问题;其次,引入Shadow Mapping方法对深度图采样,改善物体阴影绘制实时性问题,并通过纹理映射技术模拟光散射形成的焦散现象;再次,修改相位函数非对称因子g,消除海水散射对体积光的影响,提高了光在水中传播的真实性;最后,利用线性八叉树算法对其进行优化加速,保证算法的实时性.实验对比和分析表明,能够实时绘制出逼真的海下光照效果.
The simulation of ocean scene has always been a hotspot in computer graphics research. In order to solve the real-time simulation problem of sea light effect,a sea light model is proposed. Firstly,based on the ray tracing theory and Beer Lambert' s law,the problem of the interaction between seawater and light is solved by solving the luminance value integral and the light-transmitting ratio of the sampling point,Secondly,we introduce the ShadowM apping method to sample the depth map,improve the real-time problem of the shadowof the object,and simulate the caustics formed by the light scattering through the texture mapping. Furthermore,according to the scattering phase function and the conservation lawof energy,the asymmetric factor of the phase function is modified to eliminate the influence of seawater scattering on the volume of light and improve the authenticity of light propagation in the water. Finally,the linear octree algorithm is used to optimize the method and ensure the real-time performance. Experimental results showthat the algorithm can achieve realistic illumination effect in real time.
The simulation of ocean scene has always been a hotspot in computer graphics research. In order to solve the real-time simulation problem of sea light effect,a sea light model is proposed. Firstly,based on the ray tracing theory and Beer Lambert' s law,the problem of the interaction between seawater and light is solved by solving the luminance value integral and the light-transmitting ratio of the sampling point,Secondly,we introduce the ShadowM apping method to sample the depth map,improve the real-time problem of the shadowof the object,and simulate the caustics formed by the light scattering through the texture mapping. Furthermore,according to the scattering phase function and the conservation lawof energy,the asymmetric factor of the phase function is modified to eliminate the influence of seawater scattering on the volume of light and improve the authenticity of light propagation in the water. Finally,the linear octree algorithm is used to optimize the method and ensure the real-time performance. Experimental results showthat the algorithm can achieve realistic illumination effect in real time.
引文
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[2]Shah M A,Konttinen J,Pattanaik S. Caustics mapping:an imagespace technique for real-time caustics[J]. IEEE Transactions on Visualization&Computer Graphics,2007,13(13):272-280.
[3] Papadopoulos C,Papaioannou G. Realistic real-time underwater caustics and godrays[C]. Proc. 19th Int. Conf. on Computer Graphics and Vision,2009:89-95.
[4]Hu W,Dong Z,Ihrke I,et al. Interactive volume caustics in singlescattering media[J]. Symposium on Interactived Graphics&Games,2010:109-117.
[5]Gábor Liktor,Dachsbacher C. Real-time volume caustics with adaptive beam tracing[C]. Symposium on Interactive 3d Graphics&Games,San Francisco,DBLP,2011:47-54.
[6]Chen J,Baran I,Durand F,et al. Real-time volumetric shadows using 1D min-max mipmaps[C]. Symposium on Interactive 3D Graphics and Games,San Francisco ACM,2011:39-46.
[7] Tang Yong,Fan Fu-ding,Li Ying. Real-time rendeving of realistic ocean color around the islands[J]. Journal of Chinese Computer Systems,2016,37(4):847-850.
[8]Chang D,Conover A,Gustafson S. Finding particulate in finding dory[C]. ACM SIGGRAPH 2016 Talks,ACM,2016:62.
[9]Mc Guire M,Mara M. A phenomenological scattering model for order-independent transparency[C]. Proceedings of the 20th ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games,Anaheim,ACM,2016:149-158.
[7]唐勇,范福鼎,李颖.近岛海洋场景海水色彩真实感实时绘制[J].小型微型计算机系统,2016,37(4):847-850.