分布式互动投影系统多路视频图像捕获仿真

互动投影系统多使用单台PC设备来完成图像捕获,所产生的画面质量低且尺寸小,难以分辨目标个体或区域,不能满足实际生活需求,故提出分布式互动投影系统多路视频图像捕获方法.利用多台PC设备构建分布式结构,进一步扩大系统捕获面积,提升其扩展性能且加强数据图像无缝拼接效果,随后通过同步捕获技术保持视频图像时序的一致性,将数据格式进行转化并填入缓存模块,最后运用高斯混合模型增强背景区域透明度,通过模型创设、更新以及评估,完成清晰视频图像的捕获.仿真结果证明,多路捕获可以提升视频图像质量,具有较高的精准度和效率,方便用户互动投影的同时,分布式结构还能稳定传输,系统鲁棒性高.     

一种基于网络的并行渲染和跨平台同步展示系统

虚拟现实的实时展示和交互的应用越来越广泛,但由于普通PC机渲染的性能问题,无法在保证帧率的条件下渲染超高分辨率的场景。基于网络的并行渲染系统具有性价比高、扩展性好等特点,并且可以输出超高分辨率的画面,适合大型的虚拟现实场景展示。该系统使用Unity3D支持虚拟现实渲染和跨平台的特性,使用PC机群基于Sort-First结构的实时并行渲染框架展示弧形超高分辨率场景,并使用网络将手机、平板和PC机群连接在一起,利用增强现实的方式同步展示整个场景。该系统支持多机同时连接展示,可以应用到博物馆、教学、展览等领域。     

一个通用的投影墙软件校正系统

随着计算机图形硬件以及分布式并行图形绘制技术的不断发展，现在图形工作站以及PC集群机所能处理的图形数据量不断上升。但是，现在计算机显示设备所能提供的显示分辨率及其有限。因此，利用多台投影仪组成投影阵列进行拼接显示的投影墙技术受到越来越多的关注；此类系统的一个关键问题就是如何校正多台投影仪，使得最后拼接显示的图像没有明显的缝隙和瑕疵。该文介绍了一套通用的与具体应用无关的投影墙软件校正系统，该系统克服了传统软件校正系统在通用性、校正速度等方面的不足，取得了很好的校正效果。     

一种基于视频捕获的多投影显示系统

随着科学技术的高速发展以及信息量的急速膨胀,具有多个输出画面的多通道计算机系统得到了广泛应用。多显示器/拼接单元系统无法生成大尺寸高分辨率的无缝画面,多投影显示系统可克服这类系统的不足。提出一种基于视频捕获的多投影显示系统,它将多通道的画面显示与画面生成相分离,从而避免显示系统对画面生成系统的影响。该系统针对VGA模拟视频信号输入,给出基于三维查找表的颜色校正技术;针对非参数化成像模型的投影仪,给出多投影系统颜色校正的三阶段模型及其求解方法;针对工程实际,设计了基于自由曲面变形的交互式网格编辑工具进行多投影系统的几何校正。实验结果表明本系统及其关键技术切实有效,适用于构建投影数量中等规模的显示系统。     

面向多投影显示墙的画面校正技术

多投影显示墙是缓解对超高分辨率显示屏幕不断增长的需求与单台显示设备分辨率有限性之间矛盾的有效手段,但目前还缺乏规范化的模式和方法以支持高精度、高可靠性的画面校正.提出一种颜色校正方案以解决上述问题.首先介绍多投影显示墙画面校正中存在的主要问题和现有的解决方法;在此基础上,给出了多投影显示墙的画面校正流程和几何校正方法;然后讨论了多投影显示墙画面校正结果的评价标准,提出了投影仪的广义颜色模型和基于搜索技术的视觉无缝方法.该方案使用数码相机实现了高精度的视觉无缝画面校正,从而提高了构造多投影显示墙的效率并降低了维护成本.校正结果在多种类型的投影墙系统中得到验证和应用,对指导多投影显示墙的搭建和维护具有较高的理论与实践价值.     

浅析虚拟现实关键技术在展示设计中的运用--以江苏软件园展厅设计为例

当今,随着多媒体互动投影系统的飞速发展,展厅设计中采用越来越多先进的计算机视觉技术和投影显示技术来营造现代展厅的的交互交互氛围,如何实现多媒体展项技术实现途径、关键技术、难点与风险处理措施是本文所阐述的重点。     

一种面向VR多投影环幕设备的可视化结果显示方法

传统显示设备难以满足大规模复杂数据可视化结果显示的需求,而VR多投影环幕显示设备提供的沉浸式显示环境可以良好地应对复杂数据可视化显示的使用情景。提出一种面向VR多投影环幕设备的可视化结果显示方法,通过设计多投影环境中兼容2D与3D显示的渲染流程,解决了传统方法中出现的画面渲染模糊问题。同时,该方法通过3D运动模拟计算以及交互射线计算解决了在新渲染流程下的立体显示和交互坐标转换问题。实验结果表明,该方法有效地提高了多投影环境中可视化结果画面的清晰度,并支持立体显示与交互。     

一种面向多投影视频播放的系统架构和集群管理

集群驱动的多投影视频播放系统能够提供大尺寸、高分辨率的显示画面,在展览展示领域得到广泛应用。虽然许多研究讨论了如何构建集群驱动的视频播放系统,但高可靠性却一直被忽略。当硬件或软件发生异常时,已有视频播放系统难以正常工作。基于对集群驱动的视频播放系统可靠性分析,提出一种面向多投影视频播放的系统架构与集群管理。系统由集群驱动,包含一个Master节点和多个Slave节点,节点身份在启动阶段动态确定。系统采用帧同步刷新策略,保证各个节点同步播放相同序列号视频帧。Master节点负责集群自主管理,Master节点能迅速检测到陷入失效状态的和从异常状态中恢复的Slave节点,并进行相应的处理,实现容错性与可恢复性。采用上述技术构建的多投影视频播放系统已成功应用于2010年上海世博会世博会博物馆。     

一种面向多投影显示的全景视频分块编码方法

近年来虚拟现实技术快速发展,全景视频内容生成技术不断进步。内容呈现方面,多投影显示设备可通过集群驱动解决单机性能有限的问题,具有视角广、分辨率高、支持多人参与的优点。针对多投影显示设备的特点,设计并实现了一套全景视频分块编码格式及其相应的转码工具。该格式以现有的JPEG图像序列编码研究为基础,添加对立体全景视频分块编码的支持,实现双分辨率视频流动态适配机制,保证视角变化时视频的流畅播放,并添加非均匀分块编码的支持以针对实际需求定制分块参数,优化播放性能。实验结果表明,该方法可以有效提升多投影显示设备中高分辨率全景视频播放的流畅度。     

面向多投影显示墙的手势交互系统设计与实现

在PC集群驱动的多投影显示环境下,设计并实现了一个基于计算机视觉技术和数据手套的手势交互系统(gesture-based interaction system,GBIS).GBIS整合了满足色彩一致性和特征一致性的特征点跟踪算法来实现交互动作的捕捉,并配合数据手套的有限状态机输出,实现了实时的沉浸式手势交互.实验结果表明:当所用摄像头的采集频率不低于30帧时,该系统能够实时地跟踪手臂的交互动作,同时保持较高的跟踪精度和交互可靠性.     

分布交互式仿真中的高性能时钟设计问题研究

时空一致性是分布交互式仿真的关键问题，联网仿真的计算机之间的的时间同步必须达到一定的精度，而计算机的时钟分辨率是制约仿真系统时间同步精度的重要因素。在Windnws2000／NT操作系统下PC机系统时钟的分辨率较低，且时间漂移率较高，因此在使用PC机和Windows2000／NT操作系统的分布交互式仿真系统中，如果使用系统时钟，时间同步精度不可能很高，如果为每台PC机加装高性能外部时钟的话，不但会增加系统成本，而且也不利于系统扩展。该文提出了一种基于PC机性能计数器的高分辨率、低时间漂移时钟的设计方案，解决了分布交互式仿真系统基于PC机自身资源获取高性能时钟的问题。     

Interactive ray tracing for volume visualization

Presents a brute-force ray-tracing system for interactive volume visualization. The system runs on a conventional (distributed) shared-memory multiprocessor machine. For each pixel, we trace a ray through a volume to compute the color for that pixel. Although this method has a high intrinsic computational cost, its simplicity and scalability make it ideal for large data sets on current high-end parallel systems. To gain efficiency, several optimizations are used, including a volume bricking scheme and a shallow data hierarchy. These optimizations are used in three separate visualization algorithms: isosurfacing of rectilinear data, isosurfacing of unstructured data, and maximum-intensity projection on rectilinear data. The system runs interactively (i.e. at several frames per second) on an SGI Reality Monster. The graphics capabilities of the Reality Monster are used only for display of the final color image     

An architecture for Java-based real-time distributed visualization

In this paper, we present a Java-based software architecture for real-time visualization that utilizes a cluster of conventional PCs to generate high-quality interactive graphics. Normally, a large multiprocessor computer would be needed for interactive visualization tasks requiring more processing power than a single PC can provide. By using clusters of PCs, enormous cost savings can be realized, and proprietary "high-end" hardware is no longer necessary for these tasks. Our architecture minimizes the amount of synchronization needed between PCs, resulting in excellent scalability. It provides a modular framework that can accommodate a wide variety of rendering algorithms and data formats, provided that the rendering algorithms can generate pixels individually and the data is duplicated on each PC. Demonstration modules that implement ray tracing, fractal rendering, and volume rendering algorithms were developed to evaluate the architecture. Results are encouraging-using 15 PCs connected to a standard 100 Megabit/s Ethernet network, the system can interactively render simple to moderately complex data sets at modest resolution. Excellent scalability is achieved; however, our tests were limited to a cluster of 15 PCs. Results also demonstrate that Java is a viable platform for real-time distributed visualization.     

Layered interactive convergence for distributed clock synchronization

A clock synchronization service ensures that spatially dispersed and heterogeneous processors in a distributed system share a common notion of time. In order to behave as a single, unified computing resource, distributed systems have need for a fault-tolerant, clock synchronization service. One approach employs the interactive convergence (ICV) method, which is both fully distributed and inherently fault-tolerant. However, this approach suffers from limits in terms of system scalability due to resource overhead. In this paper, a new layered form of ICV is introduced, compared with basic ICV and other simpler alternatives via experimental analysis on a distributed system testbed, and shown to improve synchronization tightness, resource utilization, and scalability.     

Garuda: a scalable tiled display wall using commodity PCs

Cluster-based tiled display walls can provide cost-effective and scalable displays with high resolution and a large display area. The software to drive them needs to scale too if arbitrarily large displays are to be built. Chromium is a popular software API used to construct such displays. Chromium transparently renders any OpenGL application to a tiled display by partitioning and sending individual OpenGL primitives to each client per frame. Visualization applications often deal with massive geometric data with millions of primitives. Transmitting them every frame results in huge network requirements that adversely affect the scalability of the system. In this paper, we present Garuda, a client-server-based display wall framework that uses off-the-shelf hardware and a standard network. Garuda is scalable to large tile configurations and massive environments. It can transparently render any application built using the Open Scene Graph (OSG) API to a tiled display without any modification by the user. The Garuda server uses an object-based scene structure represented using a scene graph. The server determines the objects visible to each display tile using a novel adaptive algorithm that culls the scene graph to a hierarchy of frustums. Required parts of the scene graph are transmitted to the clients, which cache them to exploit the interframe redundancy. A multicast-based protocol is used to transmit the geometry to exploit the spatial redundancy present in tiled display systems. A geometry push philosophy from the server helps keep the clients in sync with one another. Neither the server nor a client needs to render the entire scene, making the system suitable for interactive rendering of massive models. Transparent rendering is achieved by intercepting the cull, draw, and swap functions of OSG and replacing them with our own. We demonstrate the performance and scalability of the Garuda system for different configurations of display wall. We also show that the server and network loads grow sublinearly with the increase in the number of tiles, which makes our scheme suitable to construct very large displays.     

基于投影技术的虚拟文物展示系统

为了更好地将投影映射技术应用于博物馆的数字展览,获得高质量的投影效果,设计出一套具有真实感的3D效果和高保真外观的三维数字文物展示系统.该系统利用机械旋转的实物模型和真实文物的图像,将多投影映射技术和光学透视显示相结合,采用几何学与辐射定标方法,在不发生透视畸变的情况下,将高质量的文物纹理正确地投射到动态的3D文物模型投影面上,增加投影效果和投影内容的自由度.为了评估该系统在一般博物馆环境光的影响和周围物阴影遮挡等问题,利用不同强度的光线对该系统投影区和展示区进行了测试,证明了该系统对周围环境光具有较强的鲁棒性和博物馆环境下的部署潜力,使博物馆数字文物展示内容变得更为丰富.     

虚拟环境中的空间立体声显示

介绍了虚拟环境中面向扬声器的空间立体声生成和定位的研究现状、矢量基幅值相移算法，讨论了有关声音仿真的若干问题。针对某大型分布式虚拟战场环境，构造并实现了DIS/HLA体系结构下实时3维空间立体声系统，分析了该系统中空间扬声器阵列声音显示的若干问题。提出了声觉信息显示包围球的概念，进而提出了一种以虚拟观察者／听者为中心的包围球内声源目标快速检索算法，解决了分布交互仿真中感兴趣区域大量实体声源的实时显示问题，该方法用于实际系统，效果良好。     

A scalable distributed paradigm for multi-user interaction with tiled rear projection display walls

We present the first distributed paradigm for multiple users to interact simultaneously with large tiled rear projection display walls. Unlike earlier works, our paradigm allows easy scalability across different applications, interaction modalities, displays and users. The novelty of the design lies in its distributed nature allowing well-compartmented, application independent, and application specific modules. This enables adapting to different 2D applications and interaction modalities easily by changing a few application specific modules. We demonstrate four challenging 2D applications on a nine projector display to demonstrate the application scalability of our method: map visualization, virtual graffiti, virtual bulletin board and an emergency management system. We demonstrate the scalability of our method to multiple interaction modalities by showing both gesture-based and laser-based user interfaces. Finally, we improve earlier distributed methods to register multiple projectors. Previous works need multiple patterns to identify the neighbors, the configuration of the display and the registration across multiple projectors in logarithmic time with respect to the number of projectors in the display. We propose a new approach that achieves this using a single pattern based on specially augmented QR codes in constant time. Further, previous distributed registration algorithms are prone to large misregistrations. We propose a novel radially cascading geometric registration technique that yields significantly better accuracy. Thus, our improvements allow a significantly more efficient and accurate technique for distributed self-registration of multi-projector display walls.     

并行和分布式计算机监测系统的实现原理

通用分布式监测系统ＭＳ－１是一种面向并行和分布式计算机系统而设计的行为监测和分析系统。它基于事件驱动的监测原理，并采用软硬件混合实现方式和扩充插 ＰＣ机联网的分布式结构。     

可恢复的软件DSM系统JIACKPT

软件DSM(distributed shared memory)系统在机群上构造了共享存储编程环境,结合了共享存储的易编程性和机群的可扩展性,引起了广泛的研究.由于软件DSM系统是一个分布式系统,系统失败风险大,需要实现容错技术以促进其实用化.利用用户级检查点技术,在支持域存储一致模型的软件DSM系统JIAJIA的基础上,设计并实现了一个可恢复的高可移植的软件DSM系统JIACKPT(JIAjia with ChecKPoinTing).由于采用适合软件DSM系统的强全局一致状态以及多种优化措施,JIACKPT易于实现且获得很好的性能.在一个8节点的PC机群上的应用测试表明,即使每分钟做一次检查点,大部分应用的检查点开销也小于10%.此外,JIACKPT还具有高可移植性.这些都表明JIACKPT已经成为一个比较实用的系统.