虚拟环境中自然景物模拟研究
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摘要
自然景物模拟技术是计算机图形学领域具有挑战性的课题,在航空航天、影视广告、室外设计、虚拟培训中有着广泛的应用和关注。由于自然景物几何结构复杂,运动规律不规则,很难用传统的欧式几何的方法来描述,因此目前研究中存在很多问题。雪、雨和云是三种典型的自然景物,在日常生活中随处可见,在虚拟环境中也必不可少。本文主要针对这三种典型的自然景物的模拟进行研究。
本文首先分析了自然景物的特点以及由其特点决定的模拟的复杂性,讨论了自然景物模拟常用的几种方法。深入研究了粒子系统理论,结合降雪的特点,对降雪过程进行了基于粒子系统模型的模拟。针对降雪环境的模糊问题和雪花落地的积雪现象提出将雾化效果应用于降雪的虚拟环境中的方法。
在雪粒子模型的基础上,结合降雨的特点和空气动力学理论对降雨进行了模拟。对雨滴落入水面形成的水波纹问题进行研究,改进四点水波纹算法,提出适合实时渲染虚拟环境的八点水波纹线性模拟算法。
本文设计并实现了基于Perlin噪音的体积云的模拟算法,实现了卷云、积云和层云的模拟。由于Perlin噪音对云的物理活动的模拟还有所欠缺,因此本文设计并实现了基于细胞自动机理论的云的动态模拟算法,实现了云的生成、消失以及风吹云的动态效果模拟。在云的消失过程中引入消失概率变量,解决了云的缓慢消失以及消失后的再生成问题。
The technology of natural phenomena simulation is a challenging problem in computer graphics. The people in many fields, such as aviation and spaceflight, movie, TV, advertisement, the design of outside and virtual train, show great concern about the development of this subject. However, there are some difficult issues in the process of research. Since the geometry configuration of natural phenomena is complex and the movement disciplinarian of it is abnormal, and it is too difficult to describe in the way of traditional Euclid Geometry. Snow, rain and cloud are three kinds of natural phenomena which can be seen anywhere in daily life, it is necessary in virtual environment. The simulation of three kinds of typical natural phenomena is studied in this paper.
This paper first analyzes the characteristic of natural phenomena, the complexity of natural phenomena simulation which is decided by the characteristic of natural phenomena and talks about some common used methods of natural phenomena simulation. Particle system theory is further studied in this paper, with the characteristic of snowing; based on particle system model, the process of snowing is simulated. The method of applying pulverization to virtual environment is proposed to solve the problem of the blur of snowing environment and firn phenomena.
Based on the snow particle model, with the characteristic of raining and the air dynamics, the process of raining is simulated in this paper. Water wave phenomena which is the rain drops into the water is studied, eight points water wave linear simulation arithmetic which is suit for real-time rending virtual environment is proposed by improving four points water wave arithmetic.
This paper designs and realizes the volume cloud simulation arithmetic which is based on Perlin noise, and realized the simulation of cirrus, cumulus and stratus. Perlin noise is short of simulating cloud physical sports, so based on the CA theory cloud dynamic simulation arithmetic is designed and applied, the formation, extinction and movement of the blowing winds of cloud are realized, and extinction probability variables are introduced into the process of cloud extinction to solve the problem of cloud slow extinction and formation after extinction.
本文首先分析了自然景物的特点以及由其特点决定的模拟的复杂性,讨论了自然景物模拟常用的几种方法。深入研究了粒子系统理论,结合降雪的特点,对降雪过程进行了基于粒子系统模型的模拟。针对降雪环境的模糊问题和雪花落地的积雪现象提出将雾化效果应用于降雪的虚拟环境中的方法。
在雪粒子模型的基础上,结合降雨的特点和空气动力学理论对降雨进行了模拟。对雨滴落入水面形成的水波纹问题进行研究,改进四点水波纹算法,提出适合实时渲染虚拟环境的八点水波纹线性模拟算法。
本文设计并实现了基于Perlin噪音的体积云的模拟算法,实现了卷云、积云和层云的模拟。由于Perlin噪音对云的物理活动的模拟还有所欠缺,因此本文设计并实现了基于细胞自动机理论的云的动态模拟算法,实现了云的生成、消失以及风吹云的动态效果模拟。在云的消失过程中引入消失概率变量,解决了云的缓慢消失以及消失后的再生成问题。
The technology of natural phenomena simulation is a challenging problem in computer graphics. The people in many fields, such as aviation and spaceflight, movie, TV, advertisement, the design of outside and virtual train, show great concern about the development of this subject. However, there are some difficult issues in the process of research. Since the geometry configuration of natural phenomena is complex and the movement disciplinarian of it is abnormal, and it is too difficult to describe in the way of traditional Euclid Geometry. Snow, rain and cloud are three kinds of natural phenomena which can be seen anywhere in daily life, it is necessary in virtual environment. The simulation of three kinds of typical natural phenomena is studied in this paper.
This paper first analyzes the characteristic of natural phenomena, the complexity of natural phenomena simulation which is decided by the characteristic of natural phenomena and talks about some common used methods of natural phenomena simulation. Particle system theory is further studied in this paper, with the characteristic of snowing; based on particle system model, the process of snowing is simulated. The method of applying pulverization to virtual environment is proposed to solve the problem of the blur of snowing environment and firn phenomena.
Based on the snow particle model, with the characteristic of raining and the air dynamics, the process of raining is simulated in this paper. Water wave phenomena which is the rain drops into the water is studied, eight points water wave linear simulation arithmetic which is suit for real-time rending virtual environment is proposed by improving four points water wave arithmetic.
This paper designs and realizes the volume cloud simulation arithmetic which is based on Perlin noise, and realized the simulation of cirrus, cumulus and stratus. Perlin noise is short of simulating cloud physical sports, so based on the CA theory cloud dynamic simulation arithmetic is designed and applied, the formation, extinction and movement of the blowing winds of cloud are realized, and extinction probability variables are introduced into the process of cloud extinction to solve the problem of cloud slow extinction and formation after extinction.
引文
[1]周惠.航天视景仿真特殊效果图形生成技术[J].系统仿真学报,2001,13(6).
[2] Perlin K. An Image Synthesizer[J]. Computer Graphics, 1985,19(3):263~270.
[3] Perchey D. R. Solid Texturing of Complex Surfaces[J]. Computer Graphics, 1985, 19(3):279~286.
[4] Reeves W. T. Particle System-A Technique for Modeling A Class of Fuzzy Objects[J]. Computer Graphics, 1983, 17(2):359~376.
[5] Reeves W.T. Blau R. Approximate and Probabilistic Algorithms for Shading and Rendering Structured Particle Systems [J]. Computer Graphics, 1985, 19(3):313~222.
[6]王静秋.基于粒子系统的动态自然景物模拟的研究[D].南京:南京航空航天大学,1999.
[7] Karl Sims. Particle Animation and Rendering Using Data Parallel Computation[J]. Computer Graphics,1990,24 (4):405~413.
[8] Loke, Teng-See, Tan, et al. Rendering Fireworks Displays[J]. IEEE Computer Graphics and Applications, 1992,12(3):33~43.
[9] Stolk J. Van Wijk J J. Surface Particle for 3D Flow Visualization[R], Post F H, H in A J (Eds),Springcr, Berlin, 1992.
[10] Szeliski R. Tonnesen D. Surface Modeling with Oriented Particle Systems[C]. Computer Graphics (SIGGRAPH 92),1992, 26 (3):185~194.
[11] Unbescheiden M. Trembilski A. Cloud Simulation in Virtual Environments[J]. IEEE Visualization Proceedings,1998,98~104.
[12]万华根,金小刚,彭群生.基于物理模型的实时喷泉水流运动模拟[J].计算机学报,1998,21(9):774~779.
[13]管宇,邹林灿,陈为,彭群生.基于粒子系统的实时瀑布模拟[J].系统仿真学报,2004,16(11):2471~3474.
[14]张芹,谢隽义等.火焰、烟、云等不规则物体的建模方法研究综述[J].中国图象图形学报,2000,5A(3):86~92.
[15] Prusinkiewicz P. Lindenmayer A. The Algorithmic Beauty of Plants[J]. Spring-Verlag, New York,1990.
[16] P.Prusinkiewicz , R. Karwowski, R.Mech, J. Hanan L-Studio/cpfg: A Software for Modeling Plants[R]. 2000,Lecture Notes in Computer Science,1779,Springe-Verlag, Berlin,2000,457~464.
[17]陶闯,林宗坚,卢健.分形地形模拟[J],计算机辅助设计与图形学学报,1996,8(3):178~186.
[18]齐越,沈旭昆,段米毅,程惠琳.基于Perlin噪音绘制云的方法[J].系统仿真学报,2002,14(9):1024~1027.
[19]张兆顺,崔桂香.流体力学[M].北京:清华大学出版社,1999,91~128.
[20] Jerry Tessendorf, Simulating Ocean Water[C].In SIGGRAPH 2004 Course Notes 31:The Elements of Nature: Interactive and Realistic Techniques,2004.
[21]谢剑斌,郝建新,蔡宣平,孙茂印.基于粒子系统的雨点和雪花降落模拟生成[J].中国图象图形学报.1999.9.
[22]徐利明,姜昱明.基于粒子系统与OpenGL的实时雨雪模拟[J].计算机仿真,2005,22(7):242~245.
[23]陈蕾.粒子系统理论及其在飞行模拟器实时视景仿真中的应用研究[D].吉林:吉林大学,2004,54~55.
[24]王润杰,田景全,倪政国.基于粒子系统的实时雨雪模拟[J].系统仿真学报,2003,15(4):495~501.
[25] Richard S Wright, Benjamin Lipchak(美).OpenGL超级宝典(第三版)[M], 2005.9.
[26]左鲁梅,黄心渊.纹理映射技术在三维游戏引擎中的应用[J].计算机仿真2004,21(10):146~148.
[27]陈和平,王早.水波特效模拟原理及其快速实现方法[J],计算机应用研究,2005,252~255.
[28] Breen D E, House D H, Getto P H. A Physically-based Particle Model of Woven Cloth[J].The Visual Computer,1992,8(5):264~277.
[29] Segal, Mark, Carl Korobkin, Rolf van Widenfelt, Jim Foran and Paul Haeberli, Fast Shadows and Lighting Effects using Texture Mapping[J]. Computer Graphics 1992,26(2):249~252.
[30]石教英.虚拟现实基础及实用算法[M].科学出版社,2002,4.
[31]罗维佳,都金康,谢顺平.基于粒子系统的三维场地降雨实时模拟[J].中国图象学报,2004 ,9(4):495~500.
[32]李苏军,吴玲达.基于粒子系统的实时雨模拟[J].计算机工程,2007,33(18):236~238.
[33]吕宏兴,武春龙,熊运章.雨滴降落速度的数值模拟[J].土壤侵蚀与水土保持学报,1997,3(2):10~21.
[34] Simon Premoze, Michael Ashikhmin. Rendering Natural Waters[C]. Eight Pacific Conference on Computer Graphics and Applications, October 2000.
[35] Gavin Miller,Andrew Pearce. Globular Dynamics:a Connected Particle System for Animating Viscous Fliuds[J]. Computers Graphics,1989.
[36] Dobashi, Y. Nishita, T. Yamashita, H. and Okita, T. (1999). Using Meatballs to Modeling and Animate Clouds from Satellite Images[J]. The Visual Computer, 15:471-482.
[37] Kajiya, J.T. The Rendering Equation[C]. Computer Graphics (SIGGRAPH 86 Proceedings) ,1986,20(4):143-150.
[38] Yoshinori Dobashi, Kazufumi Kaneda, Hideo Yamashita, Tsuyoshi Okita, Tomoyuki Nishita. A Simple, Efficient Method for Realistic Animation of Clouds[C]. Proc. SIGGRAPH 2000.
[39] Mark J. Harris, William V. Baxter III, Thorsten Scheuermann, Anselmo Lastra. Simulation of Cloud Dynamics on Graphics Hardware[J].Graphics Hardware 2003.
[40] Ebert D, Carlson W, Parent R. Solid spaces and inverse particle systems for controlling the animation of gases and fluids[J]. The Visual Computer, 1994, 10(4):179-190.
[41] K. Nagel, E. Raskchke. Self-Organizing Criticality in Cloud Formation[J]. Physica A.,182, 1992:519~531.
[42] Dave Shreiner, Mason Woo, Jackie Neider, Tom Davis. OpenGL编程指南(第5版)[M].机械工业出版社,2006,6.
[43]刘晓东,熊海桥,蒋立华,罗秩先.利用BillBoard实现虚拟植物集群生长显示[J].计算机工程,29(13):52~56.
[44] Mandelbrot, B. B. The Fractal Geometry of Nature[J]. Freeman, New York, 1982.
[45] Y.Dobashi, T.Nishita, T.Okita. Animation of Clouds Using Cellular Automaton[C]. Proc. Of Computer Graphics and Imaging 1998:251~256.
[46]冯金辉.树在风中的摇曳——基于物理的计算机动画[J] .计算机学报,1998,(9)
[2] Perlin K. An Image Synthesizer[J]. Computer Graphics, 1985,19(3):263~270.
[3] Perchey D. R. Solid Texturing of Complex Surfaces[J]. Computer Graphics, 1985, 19(3):279~286.
[4] Reeves W. T. Particle System-A Technique for Modeling A Class of Fuzzy Objects[J]. Computer Graphics, 1983, 17(2):359~376.
[5] Reeves W.T. Blau R. Approximate and Probabilistic Algorithms for Shading and Rendering Structured Particle Systems [J]. Computer Graphics, 1985, 19(3):313~222.
[6]王静秋.基于粒子系统的动态自然景物模拟的研究[D].南京:南京航空航天大学,1999.
[7] Karl Sims. Particle Animation and Rendering Using Data Parallel Computation[J]. Computer Graphics,1990,24 (4):405~413.
[8] Loke, Teng-See, Tan, et al. Rendering Fireworks Displays[J]. IEEE Computer Graphics and Applications, 1992,12(3):33~43.
[9] Stolk J. Van Wijk J J. Surface Particle for 3D Flow Visualization[R], Post F H, H in A J (Eds),Springcr, Berlin, 1992.
[10] Szeliski R. Tonnesen D. Surface Modeling with Oriented Particle Systems[C]. Computer Graphics (SIGGRAPH 92),1992, 26 (3):185~194.
[11] Unbescheiden M. Trembilski A. Cloud Simulation in Virtual Environments[J]. IEEE Visualization Proceedings,1998,98~104.
[12]万华根,金小刚,彭群生.基于物理模型的实时喷泉水流运动模拟[J].计算机学报,1998,21(9):774~779.
[13]管宇,邹林灿,陈为,彭群生.基于粒子系统的实时瀑布模拟[J].系统仿真学报,2004,16(11):2471~3474.
[14]张芹,谢隽义等.火焰、烟、云等不规则物体的建模方法研究综述[J].中国图象图形学报,2000,5A(3):86~92.
[15] Prusinkiewicz P. Lindenmayer A. The Algorithmic Beauty of Plants[J]. Spring-Verlag, New York,1990.
[16] P.Prusinkiewicz , R. Karwowski, R.Mech, J. Hanan L-Studio/cpfg: A Software for Modeling Plants[R]. 2000,Lecture Notes in Computer Science,1779,Springe-Verlag, Berlin,2000,457~464.
[17]陶闯,林宗坚,卢健.分形地形模拟[J],计算机辅助设计与图形学学报,1996,8(3):178~186.
[18]齐越,沈旭昆,段米毅,程惠琳.基于Perlin噪音绘制云的方法[J].系统仿真学报,2002,14(9):1024~1027.
[19]张兆顺,崔桂香.流体力学[M].北京:清华大学出版社,1999,91~128.
[20] Jerry Tessendorf, Simulating Ocean Water[C].In SIGGRAPH 2004 Course Notes 31:The Elements of Nature: Interactive and Realistic Techniques,2004.
[21]谢剑斌,郝建新,蔡宣平,孙茂印.基于粒子系统的雨点和雪花降落模拟生成[J].中国图象图形学报.1999.9.
[22]徐利明,姜昱明.基于粒子系统与OpenGL的实时雨雪模拟[J].计算机仿真,2005,22(7):242~245.
[23]陈蕾.粒子系统理论及其在飞行模拟器实时视景仿真中的应用研究[D].吉林:吉林大学,2004,54~55.
[24]王润杰,田景全,倪政国.基于粒子系统的实时雨雪模拟[J].系统仿真学报,2003,15(4):495~501.
[25] Richard S Wright, Benjamin Lipchak(美).OpenGL超级宝典(第三版)[M], 2005.9.
[26]左鲁梅,黄心渊.纹理映射技术在三维游戏引擎中的应用[J].计算机仿真2004,21(10):146~148.
[27]陈和平,王早.水波特效模拟原理及其快速实现方法[J],计算机应用研究,2005,252~255.
[28] Breen D E, House D H, Getto P H. A Physically-based Particle Model of Woven Cloth[J].The Visual Computer,1992,8(5):264~277.
[29] Segal, Mark, Carl Korobkin, Rolf van Widenfelt, Jim Foran and Paul Haeberli, Fast Shadows and Lighting Effects using Texture Mapping[J]. Computer Graphics 1992,26(2):249~252.
[30]石教英.虚拟现实基础及实用算法[M].科学出版社,2002,4.
[31]罗维佳,都金康,谢顺平.基于粒子系统的三维场地降雨实时模拟[J].中国图象学报,2004 ,9(4):495~500.
[32]李苏军,吴玲达.基于粒子系统的实时雨模拟[J].计算机工程,2007,33(18):236~238.
[33]吕宏兴,武春龙,熊运章.雨滴降落速度的数值模拟[J].土壤侵蚀与水土保持学报,1997,3(2):10~21.
[34] Simon Premoze, Michael Ashikhmin. Rendering Natural Waters[C]. Eight Pacific Conference on Computer Graphics and Applications, October 2000.
[35] Gavin Miller,Andrew Pearce. Globular Dynamics:a Connected Particle System for Animating Viscous Fliuds[J]. Computers Graphics,1989.
[36] Dobashi, Y. Nishita, T. Yamashita, H. and Okita, T. (1999). Using Meatballs to Modeling and Animate Clouds from Satellite Images[J]. The Visual Computer, 15:471-482.
[37] Kajiya, J.T. The Rendering Equation[C]. Computer Graphics (SIGGRAPH 86 Proceedings) ,1986,20(4):143-150.
[38] Yoshinori Dobashi, Kazufumi Kaneda, Hideo Yamashita, Tsuyoshi Okita, Tomoyuki Nishita. A Simple, Efficient Method for Realistic Animation of Clouds[C]. Proc. SIGGRAPH 2000.
[39] Mark J. Harris, William V. Baxter III, Thorsten Scheuermann, Anselmo Lastra. Simulation of Cloud Dynamics on Graphics Hardware[J].Graphics Hardware 2003.
[40] Ebert D, Carlson W, Parent R. Solid spaces and inverse particle systems for controlling the animation of gases and fluids[J]. The Visual Computer, 1994, 10(4):179-190.
[41] K. Nagel, E. Raskchke. Self-Organizing Criticality in Cloud Formation[J]. Physica A.,182, 1992:519~531.
[42] Dave Shreiner, Mason Woo, Jackie Neider, Tom Davis. OpenGL编程指南(第5版)[M].机械工业出版社,2006,6.
[43]刘晓东,熊海桥,蒋立华,罗秩先.利用BillBoard实现虚拟植物集群生长显示[J].计算机工程,29(13):52~56.
[44] Mandelbrot, B. B. The Fractal Geometry of Nature[J]. Freeman, New York, 1982.
[45] Y.Dobashi, T.Nishita, T.Okita. Animation of Clouds Using Cellular Automaton[C]. Proc. Of Computer Graphics and Imaging 1998:251~256.
[46]冯金辉.树在风中的摇曳——基于物理的计算机动画[J] .计算机学报,1998,(9)