基于对等网络的WebVR系统关键技术研究
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摘要
WebVR是基于互联网的交互式虚拟现实系统，兼有桌面式和分布式虚拟现实系统的特征。WebVR系统在实境式电子商务、虚拟社区、虚拟展馆等方面有着广阔的应用前景，是虚拟现实发展的方向之一。目前WebVR系统在应用开发模式，虚拟场景构建方法、数据传输与交互等方面存在许多技术问题。系统在开发、布署方面缺少一个敏捷灵活、易于扩展、体验性强的的应用架构；传统的虚拟场景的构建方法技术复杂、工作量庞大、专业性强，不适合WebVR系统快速、低成本应用；系统缺少有效的虚拟场景访问、传输机制，解决Web上大规模、多作户虚拟场景访问、传输的“瓶颈”问题。本文从WebVR系统的平台架构、虚拟场景快速构建方法以及虚拟场景传输、交互机制等方面展开研究，研究成果如下：
(1)提出了一种基于P2SP网络并结合RIA技术的WebVR系统平台架构。提出了以P2SP作为网络系统平台，结合RIA技术的开发应用模式。RIA的特点和优势促进WebVR应用向着更丰富、更具有交互性和响应性的用户体验方向发展。P2SP的灵活动态用户管理能力、资源管理策略等和协同传输机制可以有效的解决大规模、多用户虚拟场景访问传输的“瓶颈”问题。
(2)提出一种基于语义的WebVR系统虚拟场景快速构建方法。在X3D物理模型之上建立语义模型对象，计算机能够识别各个物理模型的语义信息。提出了场景对象本体及承载关系本体的构建方法，在承载关系本体的约束下，辅助直接操纵方式的可视化场景构建，实现在在本体语义约束下的虚拟场景轻量化建模。场景建立后，由X3D代码生成器将场景自动转换为X3D文件，同时可以按照某种组合关系将X3D文件分为多个X3D子场景文件，以便于传输。
(3)提出了视点相关的WebVR虚拟场景协同流式传输机制。针对大规模、多用户WebVR系统中虚拟场景传输、交互问题，本文利用观察者的ROI（感兴趣区域）对当前可视场景进行判定，并引申了ROI的思想，采用了基于Level of ROI策略对场景中的对像进行优先级判定，提出了基于优先级视点相关的虚拟场景流式传输策略。针对系统中节点的流动性和资源定位资源问题，提出了基于速率统计和邻近结点选择的伙伴结点选择算法（Peer算法），并在视点相关流式传输策略的基础上提出了虚拟场景协同流式下载机制。
(4)提出了基于AJAX和X3D技术规范的系统应用层交互架构。采用AJAX技术实现虚拟场景的异步下载，采有多线程技术提高客户端的效率。采用AJAX和X3DOM实现了简单的虚拟场景漫游与交互系统。
WebVR is an interactive virtual reality system based on Internet including thecharacteristics of desktop virtual reality system and distributed virtual reality system.WebVR has broad application in reality e-commerce, online games, virtual communitiesand virtual pavilion. WebVR is one of the directions of the development of virtualreality. Currently, there are many technical problems of WebVR systems such asapplication development model, the virtual scene construction, data transmission andinteraction.The system lacks an agile, easy to expand and strong experiencingapplication architecture in development. The traditional construction method of thevirtual scene is complex, huge workload and requires highly professional specialization.It is not suitable for rapid and low-cost deployment of applications for WebVR system.The system lacks an effective virtual scene access and transport mechanisms whichresolves "bottleneck" problems on the Web to support large-scale, more households ofthe virtual scene transmission. As well as the virtual scene transmission and interactionmechanism, the paper research on the platform architecture and the rapid construction ofthe virtual scene of the WebVR system. The results are as follows:
(1) The WebVR system architecture based on P2SP network combined with RIAtechnologies is proposed. A P2SP network platform combined with RIA technologydevelopment and application of model is proposed. Features and advantages of the RIApromote WebVR application toward a richer, more interactive and responsive in userexperience aspect. Flexible and dynamic user management capabilities of P2SP,resources search strategies and cooperative transmission access mechanism caneffectively improve "bottleneck" problems in the transmission of multi-user access andlarge-scale virtual scene access.
(2) A WebVR virtual scene quickly modeling method based on semantics isproposed. A semantic model object is established on top of the in X3D physical model,thus the computer can identify the semantic information of the physical models. Thescene object and carrying the relationship between ontology is builded, of which assistsvisualization Scenes direct manipulation under the constraints of the relationalontology,Thus achieve a lightweight modeling of the virtual scene. X3D automatic codegenerator converts the scene to X3D files, meanwhile according to some combination of.the relationship, the X3D file is separated into multiple X3D sub-scene files in orderto transfer.
(3) View-dependent collaborative streaming of the virtual scene transmissionstrategy is proposed. For the transmission and interaction problems of the large-scalescenes and multi-user WebVR system, the paper using the observer’s ROI (region ofinterest) to determine the current visual scene. Then extend the idea of the ROI,using thelevel of ROI strategy to determine the priority of the scene. The priority-based flowtransmission strategy of progressive virtual scene is proposed. For the P2SP networknodes’ mobility and resource location issues, the paper use selection algorithm systembased on the rate statistics and the neighboring selection node (Peer algorithms) in P2SPWebVR. The WebVR virtual scene streaming collaborative download mechanism ispropose based on the streaming transmission strategy of the virtual scene.
(4) The interaction architecture of the system application layer is proposed basedon AJAX and X3D. AJAX realizes virtual scene asynchronous download and adoptsmulti-thread technology to improve the efficiency of the client. At last the paper usingAJAX and X3DOM to realize virtual scene navigation and interaction system.
(1)提出了一种基于P2SP网络并结合RIA技术的WebVR系统平台架构。提出了以P2SP作为网络系统平台，结合RIA技术的开发应用模式。RIA的特点和优势促进WebVR应用向着更丰富、更具有交互性和响应性的用户体验方向发展。P2SP的灵活动态用户管理能力、资源管理策略等和协同传输机制可以有效的解决大规模、多用户虚拟场景访问传输的“瓶颈”问题。
(2)提出一种基于语义的WebVR系统虚拟场景快速构建方法。在X3D物理模型之上建立语义模型对象，计算机能够识别各个物理模型的语义信息。提出了场景对象本体及承载关系本体的构建方法，在承载关系本体的约束下，辅助直接操纵方式的可视化场景构建，实现在在本体语义约束下的虚拟场景轻量化建模。场景建立后，由X3D代码生成器将场景自动转换为X3D文件，同时可以按照某种组合关系将X3D文件分为多个X3D子场景文件，以便于传输。
(3)提出了视点相关的WebVR虚拟场景协同流式传输机制。针对大规模、多用户WebVR系统中虚拟场景传输、交互问题，本文利用观察者的ROI（感兴趣区域）对当前可视场景进行判定，并引申了ROI的思想，采用了基于Level of ROI策略对场景中的对像进行优先级判定，提出了基于优先级视点相关的虚拟场景流式传输策略。针对系统中节点的流动性和资源定位资源问题，提出了基于速率统计和邻近结点选择的伙伴结点选择算法（Peer算法），并在视点相关流式传输策略的基础上提出了虚拟场景协同流式下载机制。
(4)提出了基于AJAX和X3D技术规范的系统应用层交互架构。采用AJAX技术实现虚拟场景的异步下载，采有多线程技术提高客户端的效率。采用AJAX和X3DOM实现了简单的虚拟场景漫游与交互系统。
WebVR is an interactive virtual reality system based on Internet including thecharacteristics of desktop virtual reality system and distributed virtual reality system.WebVR has broad application in reality e-commerce, online games, virtual communitiesand virtual pavilion. WebVR is one of the directions of the development of virtualreality. Currently, there are many technical problems of WebVR systems such asapplication development model, the virtual scene construction, data transmission andinteraction.The system lacks an agile, easy to expand and strong experiencingapplication architecture in development. The traditional construction method of thevirtual scene is complex, huge workload and requires highly professional specialization.It is not suitable for rapid and low-cost deployment of applications for WebVR system.The system lacks an effective virtual scene access and transport mechanisms whichresolves "bottleneck" problems on the Web to support large-scale, more households ofthe virtual scene transmission. As well as the virtual scene transmission and interactionmechanism, the paper research on the platform architecture and the rapid construction ofthe virtual scene of the WebVR system. The results are as follows:
(1) The WebVR system architecture based on P2SP network combined with RIAtechnologies is proposed. A P2SP network platform combined with RIA technologydevelopment and application of model is proposed. Features and advantages of the RIApromote WebVR application toward a richer, more interactive and responsive in userexperience aspect. Flexible and dynamic user management capabilities of P2SP,resources search strategies and cooperative transmission access mechanism caneffectively improve "bottleneck" problems in the transmission of multi-user access andlarge-scale virtual scene access.
(2) A WebVR virtual scene quickly modeling method based on semantics isproposed. A semantic model object is established on top of the in X3D physical model,thus the computer can identify the semantic information of the physical models. Thescene object and carrying the relationship between ontology is builded, of which assistsvisualization Scenes direct manipulation under the constraints of the relationalontology,Thus achieve a lightweight modeling of the virtual scene. X3D automatic codegenerator converts the scene to X3D files, meanwhile according to some combination of.the relationship, the X3D file is separated into multiple X3D sub-scene files in orderto transfer.
(3) View-dependent collaborative streaming of the virtual scene transmissionstrategy is proposed. For the transmission and interaction problems of the large-scalescenes and multi-user WebVR system, the paper using the observer’s ROI (region ofinterest) to determine the current visual scene. Then extend the idea of the ROI,using thelevel of ROI strategy to determine the priority of the scene. The priority-based flowtransmission strategy of progressive virtual scene is proposed. For the P2SP networknodes’ mobility and resource location issues, the paper use selection algorithm systembased on the rate statistics and the neighboring selection node (Peer algorithms) in P2SPWebVR. The WebVR virtual scene streaming collaborative download mechanism ispropose based on the streaming transmission strategy of the virtual scene.
(4) The interaction architecture of the system application layer is proposed basedon AJAX and X3D. AJAX realizes virtual scene asynchronous download and adoptsmulti-thread technology to improve the efficiency of the client. At last the paper usingAJAX and X3DOM to realize virtual scene navigation and interaction system.
引文
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