时空驱动的大规模真实感海洋场景实时渲染
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摘要
针对目前计算机图形学领域对于精确的时间和空间条件驱动下大规模海洋场景的研究匮乏的现状,提出一个时空驱动的大规模真实感海洋场景实时渲染框架.首先,采用天空球代替传统天空盒进行天空背景建模,弥补天空盒灵活性和真实性上的不足;引入简化天文模型进行天体位置计算,真实展现天体运行规律;其次,引入风力驱动的统一方向谱进行海浪绘制,弥补目前图形学领域利用海浪谱建模在短波绘制效果上的不足;最后,将大气散射、海洋表面以及海下光线传播作为整体考虑,构建海面综合光照渲染模型.实验表明:该框架不仅能够真实地展现在精确的时空条件下大规模海洋场景的波浪运动以及光学效果的变化,而且能够很好地满足实时应用的需要.
Rendering large-scale ocean scenes plays an important role in simulators, movies and other aspects. Because of the complexity of the ocean and the sky, it is difficult to animate large-scale realistic ocean scenes in real time, especially under precise time and space conditions. In this paper, we present a real-time rendering framework for large-scale realistic ocean scenes. In traditional real-time ocean rendering method, the skybox method consisting of a big textured cube with six images is usually used to model the sky for its rapidity and simplicity. However, it has potential problems with seams in the edge of the skybox and it is not flexible enough. In our case, we apply a skysphere method which is convenient to position the celestial bodies and to set up the light scattering model. To show the real movement of celestial bodies, we establish a simplified astronomical model to compute the position of every single celestial body in the scene. When the wind blows over the ocean, the high frequency short wave appears first, then the low frequency long wave grows. As the wave is fully grown, the long wave will be more prominent. Researchers in graphics always focus on rendering the long wave while ignoring the short wave. We apply a unified directional spectrum for long and short wind-driven waves to draw the waves, which covers the shortage of the short wave rendering. The ocean illumination is a difficult problem for computer graphics, because both the ocean and the light source are dynamic. Via the analysis of the real ocean illumination, we take the atmospheric scattering, the ocean surface reflection and the ocean subsurface scattering as a whole, and build up a comprehensive ocean lighting rendering model. With this method, we can make the ocean waves alive, and enrich the optical effects colorfully while simulating the large-scale ocean scenes under precise time and space conditions. We demonstrate the visual realism and performance of our method in various experiments, achieving high frame rates on different desktop PCs.
Rendering large-scale ocean scenes plays an important role in simulators, movies and other aspects. Because of the complexity of the ocean and the sky, it is difficult to animate large-scale realistic ocean scenes in real time, especially under precise time and space conditions. In this paper, we present a real-time rendering framework for large-scale realistic ocean scenes. In traditional real-time ocean rendering method, the skybox method consisting of a big textured cube with six images is usually used to model the sky for its rapidity and simplicity. However, it has potential problems with seams in the edge of the skybox and it is not flexible enough. In our case, we apply a skysphere method which is convenient to position the celestial bodies and to set up the light scattering model. To show the real movement of celestial bodies, we establish a simplified astronomical model to compute the position of every single celestial body in the scene. When the wind blows over the ocean, the high frequency short wave appears first, then the low frequency long wave grows. As the wave is fully grown, the long wave will be more prominent. Researchers in graphics always focus on rendering the long wave while ignoring the short wave. We apply a unified directional spectrum for long and short wind-driven waves to draw the waves, which covers the shortage of the short wave rendering. The ocean illumination is a difficult problem for computer graphics, because both the ocean and the light source are dynamic. Via the analysis of the real ocean illumination, we take the atmospheric scattering, the ocean surface reflection and the ocean subsurface scattering as a whole, and build up a comprehensive ocean lighting rendering model. With this method, we can make the ocean waves alive, and enrich the optical effects colorfully while simulating the large-scale ocean scenes under precise time and space conditions. We demonstrate the visual realism and performance of our method in various experiments, achieving high frame rates on different desktop PCs.
引文
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[2]Premo6e S,Ashikhmin M.Rendering natural waters[J].Computer Graphics Forum,2001,20(4):189-200
[3]Iwasaki K,Dobashi Y,Nishita T.A volume rendering approach for sea surfaces taking into account second order scattering using scattering maps[C]Proc of the 2003Eurographics/IEEE TVCG Workshop on Volume Graphics.New York:ACM,2003:129-136
[4]Li Qicheng,Chen Haogang,Wang Guoping,et al.Real-time ocean simulation in dynamic sky environment[J].Journal of Computer-Aided Design&Computer Graphics,2007,19(2):172-177(in Chinese)(李起成,陈昊罡,汪国平,等.动态天空环境下的实时海洋渲染[J].计算机辅助设计与图形学学报,2007,19(2):172-177)
[5]Bruneton E,Neyret F,Holzschuch N.Real-time realistic ocean lighting using seamless transitions from geometry to BRDF[J].Computer Graphics Forum,2010,29(2):487-496
[6]Liu Shiguang,Wang Ze,Peng Qunsheng.Realistic simulation of lighting effects of turbid water[J].Journal of Computer-Aided Design&Computer Graphics,2011,23(1):40-45(in Chinese)(刘世光,王泽,彭群生.基于物理的浑浊水体的光照模拟[J].计算机辅助设计与图形学学报,2011,23(1):40-45)
[7]Peng Qunsheng,Wang Changbo,Liu Shiguang.Realistic Simulation of Natural Sights[M].Hangzhou:Zhejiang University Press,2013:41-63(in Chinese)(彭群生,王长波,刘世光.自然景观的真实感模拟[M].杭州:浙江大学出版社,2013:41-63)
[8]Zhang Yuping.Real-time realistic rendering of sunrise and sunset on the ocean[D].Baltimore:University of Maryland Baltimore County,2015
[9]Horvath C J.Empirical directional wave spectra for computer graphics[C]Proc of the 2015Symp on Digital Production.New York:ACM,2015:29-39
[10]Tang Yong,Fan Fuding,Li Ying.Real-time rendering of realistic ocean color around the islands[J].Journal of Chinese Computer Systems,2016,37(4):847-850(in Chinese)(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)
[11]Ma Chunyong,Xu Shu,Wang Hongsong,et al.A real-time photo-realistic rendering algorithm of ocean color based on bio-optical model[J].Journal of Ocean University of China,2016,15(6):996-1006
[12]Garcia J,Drakeley S,Palmer S,et al.Rigging the oceans of Disney’s“Moana”[C]Proc of SIGGRAPH ASIA 2016Technical Briefs.New York:ACM,2016:No.30
[13]Palmer S,Garcia J,Drakeley S,et al.The ocean and water pipeline of Disney’s Moana[C]Proc of ACM SIGGRAPH2017Talks.New York:ACM,2017:No.29
[14]Hopper R,Kai W.The water effects of Pirates of the Caribbean:Dead Men Tell no Tales[C]Proc of ACMSIGGRAPH 2017Talks.New York:ACM,2017:No.31
[15]Schlyter P.Computing planetary positions-A tutorial with worked examples[OL].[2017-08-16].http:stjarnhimlen.se/comp/tutorial.html
[16]Jensen H W,Dorsey J,Stark M M,et al.A physicallybased night sky model[C]Proc of the 28th Annual Conf on Computer Graphics and Interactive Techniques.New York:ACM,2001:399-408
[17]Elfouhaily T,Chapron B,Katsaros K,et al.A unified directional spectrum for long and short wind-driven waves[J].Journal of Geophysical Research,1997,102(C7):15781-15796
[18]Jensen H W,Marschner S R,Levoy M,et al.A practical model for subsurface light transport[C]Proc of the 28th Annual Conf on Computer Graphics and Interactive Techniques.New York:ACM,2001:511-518
[19]Papas M,Matusik W,Matusik W,et al.Fabricating translucent materials using continuous pigment mixtures[J].ACM Transactions on Graphics,2013,32(4):No.146
[20]Frisvad J R,Hachisuka T,Kjeldsen T K.Directional dipole model for subsurface scattering[J].ACM Transactions on Graphics,2014,34(1):No.5
[21]Zhao Shuang,Ramamoorthi R,Bala K.High-order similarity relations in radiative transfer[J].ACM Transactions on Graphics,2014,33(4):No.104
[22]Wang Rui,Tran J,Luebke D.All-frequency interactive relighting of translucent objects with single and multiple scattering[J].ACM Transactions on Graphics,2005,24(3):1202-1207
[23]Wang Rui,Cheslack-Postava E,Wang Rui,et al.Real-time editing and relighting of homogeneous translucent materials[J].The Visual Computer,2008,24(7):565-575
[24]Sheng Yu,Shi Yulong,Wang Lili,et al.A practical analytic model for the radiosity of translucent scenes[C]Proc of the17th ACM SIGGRAPH Symp on Interactive 3DGraphics and Games.New York:ACM,2013:63-70
[25]Gong Yi,Chen Wei,Zhang Long,et al.An approximate image-space approach for real-time rendering of deformable translucent objects[C]Proc of the 24th Computer Graphics Int Conf.Berlin:Springer,2006:124-135
[26]Zhao Qinping,Li Shuai,Hao Aimin,et al.A real-time rendering method for subsurface scattering of dynamic objects[J].Journal of Software,2010,21(11):2959-2970(in Chinese)(赵沁平,李帅,郝爱民,等.一种动态物体次表面散射实时绘制方法[J].软件学报,2010,21(11):2959-2970)
① Texel (Texel storm),MARSEN(marine remote sensing experiment at north sea),ARSLOE(Atlantic ocean remote sensing land-ocean experiment)
[2]Premo6e S,Ashikhmin M.Rendering natural waters[J].Computer Graphics Forum,2001,20(4):189-200
[3]Iwasaki K,Dobashi Y,Nishita T.A volume rendering approach for sea surfaces taking into account second order scattering using scattering maps[C]Proc of the 2003Eurographics/IEEE TVCG Workshop on Volume Graphics.New York:ACM,2003:129-136
[4]Li Qicheng,Chen Haogang,Wang Guoping,et al.Real-time ocean simulation in dynamic sky environment[J].Journal of Computer-Aided Design&Computer Graphics,2007,19(2):172-177(in Chinese)(李起成,陈昊罡,汪国平,等.动态天空环境下的实时海洋渲染[J].计算机辅助设计与图形学学报,2007,19(2):172-177)
[5]Bruneton E,Neyret F,Holzschuch N.Real-time realistic ocean lighting using seamless transitions from geometry to BRDF[J].Computer Graphics Forum,2010,29(2):487-496
[6]Liu Shiguang,Wang Ze,Peng Qunsheng.Realistic simulation of lighting effects of turbid water[J].Journal of Computer-Aided Design&Computer Graphics,2011,23(1):40-45(in Chinese)(刘世光,王泽,彭群生.基于物理的浑浊水体的光照模拟[J].计算机辅助设计与图形学学报,2011,23(1):40-45)
[7]Peng Qunsheng,Wang Changbo,Liu Shiguang.Realistic Simulation of Natural Sights[M].Hangzhou:Zhejiang University Press,2013:41-63(in Chinese)(彭群生,王长波,刘世光.自然景观的真实感模拟[M].杭州:浙江大学出版社,2013:41-63)
[8]Zhang Yuping.Real-time realistic rendering of sunrise and sunset on the ocean[D].Baltimore:University of Maryland Baltimore County,2015
[9]Horvath C J.Empirical directional wave spectra for computer graphics[C]Proc of the 2015Symp on Digital Production.New York:ACM,2015:29-39
[10]Tang Yong,Fan Fuding,Li Ying.Real-time rendering of realistic ocean color around the islands[J].Journal of Chinese Computer Systems,2016,37(4):847-850(in Chinese)(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)
[11]Ma Chunyong,Xu Shu,Wang Hongsong,et al.A real-time photo-realistic rendering algorithm of ocean color based on bio-optical model[J].Journal of Ocean University of China,2016,15(6):996-1006
[12]Garcia J,Drakeley S,Palmer S,et al.Rigging the oceans of Disney’s“Moana”[C]Proc of SIGGRAPH ASIA 2016Technical Briefs.New York:ACM,2016:No.30
[13]Palmer S,Garcia J,Drakeley S,et al.The ocean and water pipeline of Disney’s Moana[C]Proc of ACM SIGGRAPH2017Talks.New York:ACM,2017:No.29
[14]Hopper R,Kai W.The water effects of Pirates of the Caribbean:Dead Men Tell no Tales[C]Proc of ACMSIGGRAPH 2017Talks.New York:ACM,2017:No.31
[15]Schlyter P.Computing planetary positions-A tutorial with worked examples[OL].[2017-08-16].http:stjarnhimlen.se/comp/tutorial.html
[16]Jensen H W,Dorsey J,Stark M M,et al.A physicallybased night sky model[C]Proc of the 28th Annual Conf on Computer Graphics and Interactive Techniques.New York:ACM,2001:399-408
[17]Elfouhaily T,Chapron B,Katsaros K,et al.A unified directional spectrum for long and short wind-driven waves[J].Journal of Geophysical Research,1997,102(C7):15781-15796
[18]Jensen H W,Marschner S R,Levoy M,et al.A practical model for subsurface light transport[C]Proc of the 28th Annual Conf on Computer Graphics and Interactive Techniques.New York:ACM,2001:511-518
[19]Papas M,Matusik W,Matusik W,et al.Fabricating translucent materials using continuous pigment mixtures[J].ACM Transactions on Graphics,2013,32(4):No.146
[20]Frisvad J R,Hachisuka T,Kjeldsen T K.Directional dipole model for subsurface scattering[J].ACM Transactions on Graphics,2014,34(1):No.5
[21]Zhao Shuang,Ramamoorthi R,Bala K.High-order similarity relations in radiative transfer[J].ACM Transactions on Graphics,2014,33(4):No.104
[22]Wang Rui,Tran J,Luebke D.All-frequency interactive relighting of translucent objects with single and multiple scattering[J].ACM Transactions on Graphics,2005,24(3):1202-1207
[23]Wang Rui,Cheslack-Postava E,Wang Rui,et al.Real-time editing and relighting of homogeneous translucent materials[J].The Visual Computer,2008,24(7):565-575
[24]Sheng Yu,Shi Yulong,Wang Lili,et al.A practical analytic model for the radiosity of translucent scenes[C]Proc of the17th ACM SIGGRAPH Symp on Interactive 3DGraphics and Games.New York:ACM,2013:63-70
[25]Gong Yi,Chen Wei,Zhang Long,et al.An approximate image-space approach for real-time rendering of deformable translucent objects[C]Proc of the 24th Computer Graphics Int Conf.Berlin:Springer,2006:124-135
[26]Zhao Qinping,Li Shuai,Hao Aimin,et al.A real-time rendering method for subsurface scattering of dynamic objects[J].Journal of Software,2010,21(11):2959-2970(in Chinese)(赵沁平,李帅,郝爱民,等.一种动态物体次表面散射实时绘制方法[J].软件学报,2010,21(11):2959-2970)
① Texel (Texel storm),MARSEN(marine remote sensing experiment at north sea),ARSLOE(Atlantic ocean remote sensing land-ocean experiment)
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