虚拟现实技术在数字化校园中的应用研究
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摘要
随知识经济的席卷而至和信息技术的迅速发展,教育信息化已成为时代发展的必然选择。“数字化校园”作为教育信息化众多解决方案中的一种,其整体化改革的思想得到了教育界越来越多的认同和青睐。
数字化校园是在传统校园的基础上,利用先进的信息化手段和工具,将现实校园中的各项资源数字化,形成的一个数字空间。其中的虚拟校园漫游系统,则是在计算机环境中,利用虚拟现实技术再现校园的景观,来访者足不出户就可以进入到虚拟的校园之中访问漫游,尽情领略校园的文化风情。
基于图像绘制(IBR)技术是近来兴起的一种新的虚拟现实实现方法,它以计算机视觉和图像处理等学科的理论和方法为基础,试图利用真实的图像来代替传统的几何建模,同时又用图像空间的变换操作来代替传统的绘制过程。它克服了传统的基于几何多边形绘制技术的三维建模复杂、真实感不强、场景复杂时难以实时刷新等问题,使三维场景的建立变得容易,使复杂的虚拟现实系统能在普通硬件平台上推广应用。因此它已成为当前计算机图形学研究中的一个热点,尤其是在虚拟环境的构造上有着很好的应用前景。
本文在研究和总结当前国内外有关虚拟现实技术基本理论和一些典型应用系统的基础上,对采用基于图像的图形绘制技术来构建虚拟场景的理论、方法和技术进行了深入研究,设计并实现了一个基于图像的虚拟场景漫游系统。具体完成的工作如下:
1、概述了虚拟现实技术的应用领域,国内外研究动态以及课题的研究背景及意义。
2、对虚拟数字化校园的关键技术——基于图象绘制技术进行探讨,分析了各类基于图象绘制技术的优缺点及其应用于研究难点;接着重点探讨了图像的拼接过程,分析各种算法的优劣,提出了一种基于图像边缘特征的拼接算法;
3、研究了虚拟全景图的生成技术,其中重点分析了柱面全景图的构造过程,同时研究了场景漫游时所涉及到的柱面反投影算法;并提出了一个漫游结构框架,并实现了基于全景图的市经贸学校的虚拟漫游系统。
4、对实验结果进行总结,对以后工作中需要进一步深入研究的几个方面做了一个简单的展望。
With the knowledge-based economy and swept and to the rapid development of information technology, education of information technology has become an inevitable choice for the development of the times. "Digital Campus" as many of the educational messages in a solution, its overall reform of the education sector has been thinking more and more recognition and favor.
Based on the traditional campus, digital campus is using advanced information methods and tools to form a digital space by digitalizing various resources on actual campus. Virtual campus touring system, part of the digital campus, shows the outlook of the campus via virtual reality technology under the computer environment. Visitors could surf on the virtual campus and enjoy the amorous feeling on the culture without actual visit on site. Image Based Rendering (IBR) is a new method that has been widely used in creating a virtual reality system. It is preferred over the traditional 3D geometry modeling and rendering technology that has its limitations on rendering quality and scene complexity. IBR is based on the theory and method of computer vision and image processing, and it uses photo-realistic renderings and warping. It is appealing since natural scenes, which are very difficult to model using traditional 3D geometry modeling, can be acquired semi-automatically using cameras and other devices. Also IBR has a potential to create high-quality output images if the rendering stage can preserve the quality of the reference images.
After summarizing the basic theories and technologies of VR in civil and abroad, we propose a new algorithm that is used to match two series photos to form a wider range view and develop a virtual walkthrough system called Walkthrough jingmao touris school. The main works are detailed as followed:
1、The development, the future and current situation of Virtual Reality technologies are introduced. Then the purpose and background of this thesis is introduced.
2、The key technique of virtual campus—image based rendering(IBR) is discussed, the advantage and disadvantage of several kinds of IBR technique are analyzed.then, The generation of cylinder panoramic image is studied, the image mosaic process is discussed in emphatically, the advantage and disadvantage of general image mosaicing algorithms are discussed. Moreover, an image mosaicing algorithm based on image edge feature is implemented.
3、The generation of cylinder panoramic image is studied and the inverse projective algorithm involved with the scene touring is analyzed.
4、conclusion of the result of experiment, we make a simple prospect to several aspects needing further investigating for the future in the thesis.
数字化校园是在传统校园的基础上,利用先进的信息化手段和工具,将现实校园中的各项资源数字化,形成的一个数字空间。其中的虚拟校园漫游系统,则是在计算机环境中,利用虚拟现实技术再现校园的景观,来访者足不出户就可以进入到虚拟的校园之中访问漫游,尽情领略校园的文化风情。
基于图像绘制(IBR)技术是近来兴起的一种新的虚拟现实实现方法,它以计算机视觉和图像处理等学科的理论和方法为基础,试图利用真实的图像来代替传统的几何建模,同时又用图像空间的变换操作来代替传统的绘制过程。它克服了传统的基于几何多边形绘制技术的三维建模复杂、真实感不强、场景复杂时难以实时刷新等问题,使三维场景的建立变得容易,使复杂的虚拟现实系统能在普通硬件平台上推广应用。因此它已成为当前计算机图形学研究中的一个热点,尤其是在虚拟环境的构造上有着很好的应用前景。
本文在研究和总结当前国内外有关虚拟现实技术基本理论和一些典型应用系统的基础上,对采用基于图像的图形绘制技术来构建虚拟场景的理论、方法和技术进行了深入研究,设计并实现了一个基于图像的虚拟场景漫游系统。具体完成的工作如下:
1、概述了虚拟现实技术的应用领域,国内外研究动态以及课题的研究背景及意义。
2、对虚拟数字化校园的关键技术——基于图象绘制技术进行探讨,分析了各类基于图象绘制技术的优缺点及其应用于研究难点;接着重点探讨了图像的拼接过程,分析各种算法的优劣,提出了一种基于图像边缘特征的拼接算法;
3、研究了虚拟全景图的生成技术,其中重点分析了柱面全景图的构造过程,同时研究了场景漫游时所涉及到的柱面反投影算法;并提出了一个漫游结构框架,并实现了基于全景图的市经贸学校的虚拟漫游系统。
4、对实验结果进行总结,对以后工作中需要进一步深入研究的几个方面做了一个简单的展望。
With the knowledge-based economy and swept and to the rapid development of information technology, education of information technology has become an inevitable choice for the development of the times. "Digital Campus" as many of the educational messages in a solution, its overall reform of the education sector has been thinking more and more recognition and favor.
Based on the traditional campus, digital campus is using advanced information methods and tools to form a digital space by digitalizing various resources on actual campus. Virtual campus touring system, part of the digital campus, shows the outlook of the campus via virtual reality technology under the computer environment. Visitors could surf on the virtual campus and enjoy the amorous feeling on the culture without actual visit on site. Image Based Rendering (IBR) is a new method that has been widely used in creating a virtual reality system. It is preferred over the traditional 3D geometry modeling and rendering technology that has its limitations on rendering quality and scene complexity. IBR is based on the theory and method of computer vision and image processing, and it uses photo-realistic renderings and warping. It is appealing since natural scenes, which are very difficult to model using traditional 3D geometry modeling, can be acquired semi-automatically using cameras and other devices. Also IBR has a potential to create high-quality output images if the rendering stage can preserve the quality of the reference images.
After summarizing the basic theories and technologies of VR in civil and abroad, we propose a new algorithm that is used to match two series photos to form a wider range view and develop a virtual walkthrough system called Walkthrough jingmao touris school. The main works are detailed as followed:
1、The development, the future and current situation of Virtual Reality technologies are introduced. Then the purpose and background of this thesis is introduced.
2、The key technique of virtual campus—image based rendering(IBR) is discussed, the advantage and disadvantage of several kinds of IBR technique are analyzed.then, The generation of cylinder panoramic image is studied, the image mosaic process is discussed in emphatically, the advantage and disadvantage of general image mosaicing algorithms are discussed. Moreover, an image mosaicing algorithm based on image edge feature is implemented.
3、The generation of cylinder panoramic image is studied and the inverse projective algorithm involved with the scene touring is analyzed.
4、conclusion of the result of experiment, we make a simple prospect to several aspects needing further investigating for the future in the thesis.
引文
[1]Greene N,Kass M,MillerGHierarchical Z-bufer visibility.Proceeding of SIGGRAPH 1993.231-238
[2]彭群生,鲍虎军,金小刚编著.计算机真实感图形的算法基础.北京:科学出版社
[3]苏建民,张续红,吴庆夕.展望虚拟现实技术.计算机仿真.2004年1期
[4]董士海.人机交互的进展及面临的挑战.计算机辅助设计与图形学学报,2004
[5]NOVELL网络技术基础.北京:电子工业出版社,1996.11
[6]李杰.基于图像的Internet的虚拟景观的浏览器的研究[D].广州:华南理工大学硕士学位论文,2001
[7]张茂军,李云浩等.一种基于实景图像的虚拟现实系统.小型微型计算机系统,1999,20(7):491-495
[8]贺平.高校数字化校园建设策略与实现.番禺职业技术学院学报,2004-06
[9]沈向洋,王立峰.“图象和几何的统--基于图象的绘制技术(IBR)综述”
[10]汪娟娟,康玲.虚拟现实在数字校园中的应用.计算机仿真,2003.6
[11]郝爱民,赵沁平.虚拟环境漫游引擎的设计与实现.计算机工程与应用,2000.12
[12]T.Beier and S.Neely,Feature-based image metamor-phosis.In Computer Graphics (SIGGRAPH'92),pp.35-2.ACM SIGGRAPH
[13]余莉,王乘.基于虚拟现实技术的数字校园三维仿真系统,计算机仿真,2004.4 December 1996
[14]GeoVRML.2000.http://www.ai.sri.com/geovrml/
[15]E.H.Adelson and J.Bergen.The plenoptic function and the elements of early vision.In Computational Models of Visual Processing,pages 3-20.MIT Press,Cambridge,MA,1991.
[16]M.Levoy and P.Haurahan."Light field rendering",in Computer Graphics Proceedings,Annual Conference Series,pp.31-42,Proc.SIGGRAPH'96(New Orleans),August 1996.ACM SIGGRAPH.
[17]S.J.Gortler,R.Grzeszczuk,R.Szeliski,and M.F Cohen."The lumigraph",in Computer Graphics Proceedings,Annual Conference Series,pp.43-54,Proc.SIGGRAPH'96(New Orleans),August 1996.ACM SIGGRAPH.
[18]D.G.Aliaga reconstructing 2001.and I.Carlbom."Plenoptic interactive walkthroughs",in stitching:A scalable method for ACM SIGGRAPH,pp.443-450,
[19]H.Y Shum and L.W He."Rendering with concentric mosaics",in Proc.SIGGRAPH 99,pp 299-306,1999.
[20]S.E.Chen."Quicklime VR-an image-based approach to virtual environment navigation".Computer Graphics(SIGGRAPH'95),pp.29-38,August 1995.
[21]Chen S E.Quicklime VR:an image-based approach to virtual environment navigation.Computer Graphics(SIGGRAPH 95) 1995,29-38
[22]M Jethwa,A Zisserman,A.Fitzgibbon.Real-time Panoramic Mosaics and Augmented Reality.Ninth British Machine Vision Conference,1998,852-862.
[23]S K Nayar.Omnidirectional Vision.Ninth British Nfachine Vision Conference,1998,1-12.
[24]徐月,潘志庚,石教英.虚拟现实中基于图像的绘制技术.中国图象图形学报1998,302):1005-1010页
[25]江加和,宋子善,沈为群等.虚拟现实中基于图象绘制虚拟场景技术综述.系统工程与电子技术,2000,22(10):86-89页
[26]李洪举,吴恩华.基于图像的室内虚拟环境的研究.计算机学报,1999,22(9):529-534
[27]阮宗才,梁栋,吴福朝等.一种自动全景拼图的快速算法.计算机研究与发展,2001,38(5):536-539
[28]屈婉艘,朱敏,唐卫清等.一种新的基于图像的虚拟场景重建与漫游框架.计算机工程与科学,1998年第5期
[29]http://www.compuphase.com
[30]Kanade T,Okutomi M.A stereo matching algorithm with an adaptive window:theory and experiments.IEEE Trans.On Patern Anal.Machine Intell,Sep.1994,Vol.16,no.9:920-932
[31]Loti J L,Giraudon G Adaptive window algorithm for aerial image stereo.In:Proceedings of International Conference on Pattern Recognition.1994
[32]Lotti J L,Giraudon G Correlation algorithm with adaptive window for aerial image in stereovision.In:European Symposium on Satellite Remote Sensing(EUROPTO).Rome,Italy,Sept.1994
[33]Okutomi M,Kanade T A multiple-baseline stereo.IEEE Trans.On Pattern Anal.Machine Intell,April 1993,vol.15,no.4:353-363
[34]王立峰,潘志庚,石教英.全景图象的拼合及优化算法.计算机应用研究,1999,6(6):p60-61
[35]孙立峰,钟力,李云浩等.虚拟实景空间的实时漫游.中国图象图形学报,1999,4(6):507-513
[36]http://www.ipix.com
[37]http://design.yesky.com/flash/203.2609203.shtml
[38]钟力,张茂军,孙立峰等.360度柱面全景图象生成算法及其实现.小型微型计算机系统,1999,20(12):p899-900
[39]程娟,蒋幕蓉.一种基于特征与点匹配相结合的全景图拼接算法.云南大学学报(自然科学版),2004,26(6A)
[40]孟祥旭,杨承磊.基于未校准照片构造全景图的新方法.工程图形学学报,2002,(3);110-114
[41]胡小强.虚拟现实技术[M].北京:北京邮电大学出版社,2005
[42]张茂军.虚拟现实系统.北京:科学出版社.2001
[43]张凯丽,刘辉.边缘检测技术的发展研究[J].昆明理工大学学报,2000,25(5):36
[44]刘曙光,刘明远.基于Canny准则的基数B小波边缘检测[J].信号处理。2001,17(5):418
[45]郑南宁.计算机视觉与模式识别[M].北京:国防工业出版社,1998
[46]唐正军,刘代志.改进多尺度Canny算子在SAR图像边缘提取中的应用[J].上海航天,2000(2):7
[47]章毓晋.图像分割[M],北京:科学出版社,2001
[48]张辉.基于图像的虚拟现实技术研究.西安:西安理工大学(工学硕士).2002:2-3页
[49]陈军,陆海东,袁春风.虚拟现实中虚拟景象产生的技术初探计算机应用研究.1999(6):54-55页
[50]李宏东,叶秀清,顾伟康.基于图象的真实感绘制与建模---IBR.计算机应用研究,1999(6):42-44页
[2]彭群生,鲍虎军,金小刚编著.计算机真实感图形的算法基础.北京:科学出版社
[3]苏建民,张续红,吴庆夕.展望虚拟现实技术.计算机仿真.2004年1期
[4]董士海.人机交互的进展及面临的挑战.计算机辅助设计与图形学学报,2004
[5]NOVELL网络技术基础.北京:电子工业出版社,1996.11
[6]李杰.基于图像的Internet的虚拟景观的浏览器的研究[D].广州:华南理工大学硕士学位论文,2001
[7]张茂军,李云浩等.一种基于实景图像的虚拟现实系统.小型微型计算机系统,1999,20(7):491-495
[8]贺平.高校数字化校园建设策略与实现.番禺职业技术学院学报,2004-06
[9]沈向洋,王立峰.“图象和几何的统--基于图象的绘制技术(IBR)综述”
[10]汪娟娟,康玲.虚拟现实在数字校园中的应用.计算机仿真,2003.6
[11]郝爱民,赵沁平.虚拟环境漫游引擎的设计与实现.计算机工程与应用,2000.12
[12]T.Beier and S.Neely,Feature-based image metamor-phosis.In Computer Graphics (SIGGRAPH'92),pp.35-2.ACM SIGGRAPH
[13]余莉,王乘.基于虚拟现实技术的数字校园三维仿真系统,计算机仿真,2004.4 December 1996
[14]GeoVRML.2000.http://www.ai.sri.com/geovrml/
[15]E.H.Adelson and J.Bergen.The plenoptic function and the elements of early vision.In Computational Models of Visual Processing,pages 3-20.MIT Press,Cambridge,MA,1991.
[16]M.Levoy and P.Haurahan."Light field rendering",in Computer Graphics Proceedings,Annual Conference Series,pp.31-42,Proc.SIGGRAPH'96(New Orleans),August 1996.ACM SIGGRAPH.
[17]S.J.Gortler,R.Grzeszczuk,R.Szeliski,and M.F Cohen."The lumigraph",in Computer Graphics Proceedings,Annual Conference Series,pp.43-54,Proc.SIGGRAPH'96(New Orleans),August 1996.ACM SIGGRAPH.
[18]D.G.Aliaga reconstructing 2001.and I.Carlbom."Plenoptic interactive walkthroughs",in stitching:A scalable method for ACM SIGGRAPH,pp.443-450,
[19]H.Y Shum and L.W He."Rendering with concentric mosaics",in Proc.SIGGRAPH 99,pp 299-306,1999.
[20]S.E.Chen."Quicklime VR-an image-based approach to virtual environment navigation".Computer Graphics(SIGGRAPH'95),pp.29-38,August 1995.
[21]Chen S E.Quicklime VR:an image-based approach to virtual environment navigation.Computer Graphics(SIGGRAPH 95) 1995,29-38
[22]M Jethwa,A Zisserman,A.Fitzgibbon.Real-time Panoramic Mosaics and Augmented Reality.Ninth British Machine Vision Conference,1998,852-862.
[23]S K Nayar.Omnidirectional Vision.Ninth British Nfachine Vision Conference,1998,1-12.
[24]徐月,潘志庚,石教英.虚拟现实中基于图像的绘制技术.中国图象图形学报1998,302):1005-1010页
[25]江加和,宋子善,沈为群等.虚拟现实中基于图象绘制虚拟场景技术综述.系统工程与电子技术,2000,22(10):86-89页
[26]李洪举,吴恩华.基于图像的室内虚拟环境的研究.计算机学报,1999,22(9):529-534
[27]阮宗才,梁栋,吴福朝等.一种自动全景拼图的快速算法.计算机研究与发展,2001,38(5):536-539
[28]屈婉艘,朱敏,唐卫清等.一种新的基于图像的虚拟场景重建与漫游框架.计算机工程与科学,1998年第5期
[29]http://www.compuphase.com
[30]Kanade T,Okutomi M.A stereo matching algorithm with an adaptive window:theory and experiments.IEEE Trans.On Patern Anal.Machine Intell,Sep.1994,Vol.16,no.9:920-932
[31]Loti J L,Giraudon G Adaptive window algorithm for aerial image stereo.In:Proceedings of International Conference on Pattern Recognition.1994
[32]Lotti J L,Giraudon G Correlation algorithm with adaptive window for aerial image in stereovision.In:European Symposium on Satellite Remote Sensing(EUROPTO).Rome,Italy,Sept.1994
[33]Okutomi M,Kanade T A multiple-baseline stereo.IEEE Trans.On Pattern Anal.Machine Intell,April 1993,vol.15,no.4:353-363
[34]王立峰,潘志庚,石教英.全景图象的拼合及优化算法.计算机应用研究,1999,6(6):p60-61
[35]孙立峰,钟力,李云浩等.虚拟实景空间的实时漫游.中国图象图形学报,1999,4(6):507-513
[36]http://www.ipix.com
[37]http://design.yesky.com/flash/203.2609203.shtml
[38]钟力,张茂军,孙立峰等.360度柱面全景图象生成算法及其实现.小型微型计算机系统,1999,20(12):p899-900
[39]程娟,蒋幕蓉.一种基于特征与点匹配相结合的全景图拼接算法.云南大学学报(自然科学版),2004,26(6A)
[40]孟祥旭,杨承磊.基于未校准照片构造全景图的新方法.工程图形学学报,2002,(3);110-114
[41]胡小强.虚拟现实技术[M].北京:北京邮电大学出版社,2005
[42]张茂军.虚拟现实系统.北京:科学出版社.2001
[43]张凯丽,刘辉.边缘检测技术的发展研究[J].昆明理工大学学报,2000,25(5):36
[44]刘曙光,刘明远.基于Canny准则的基数B小波边缘检测[J].信号处理。2001,17(5):418
[45]郑南宁.计算机视觉与模式识别[M].北京:国防工业出版社,1998
[46]唐正军,刘代志.改进多尺度Canny算子在SAR图像边缘提取中的应用[J].上海航天,2000(2):7
[47]章毓晋.图像分割[M],北京:科学出版社,2001
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