视频增强的新方法

本文使用张量的方法推导了基于仿射空间的免标定增强现实方法,该方法不需要像机的标定参数和环境对象的3D位置信息就可实现视频增强。同时,本文也提出了在仿射空间解决增强现实中遮挡问题的新方法,给出了基于免标定增强现实的视频增强主要想法和应用实例。结果表明,这个方法是可行的。     

用于虚拟现实的360度视频编码技术新进展*

随着虚拟现实技术不断发展,360度视频编码开始成为研究热点。应用于虚拟现实的360度视频与传统的视频相比分辨率更高,编码数据量更大,在实际应用中面临传输带宽有限的瓶颈,编码效率问题有待解决。归纳分析了国际标准组织联合视频研究组（joint video exploration team, JVET）正在制定的360度视频编码投影变换技术及其编码优化方法,综合对比了各变换技术的编码性能。根据当前最新研究成果,对下一步研究需要解决的问题进行了探讨总结,给出未来的研究方向和思路。     

Video Coding for Mobile Handheld Conferencing

Since the time of Dick Tracy cartoons, the idea of wearable videoconferencing devices has been a desirable but unachievable goal. Current technology is now on the verge of making this dream a reality. Existing and future low bit-rate video coding standards such as H.263 and MPEG-4 may require specialized hardware for real-time handheld video conferencing [3]. This paper evaluates the performance of software-based videoconferencing on widely available mobile handheld devices using a range of both traditional and original video coding schemes. Our results demonstrate that wearable videoconferencing can no longer be relegated to the realm of science fiction as practical first generation devices are feasible today.     

基于ARToolKit工具的增强现实交互操作研究

增强现实是把计算机生成的虚拟图像或其它信息叠加到用户所看到的真实世界中的一种技术。ARToolKit为增强现实技术的应用提供了一种方便快捷的开发工具,但多针对于浏览展示方面。本文在ARToolKit工具下针对AVI录像文件进行增强现实的应用开发,增加了用户和现实以及虚拟物体的交互操作,通过计算机视觉的方法着重解决把虚拟物体放置到用户在视频帧上指定的点。这些将为用户使用增强现实技术进行设计和规划提供方便。     

混合结构视频网格的构造与性能分析

针对可扩展视频网格结构中,由于加盟服务器数量不足所引起的区域服务器负载波动随在线用户数量变化过大的问题,引入P2P技术构造混合结构的视频网格,实现普通客户端之间视频流数据的直接传输。论述了P2P点播组的构成,资源的管理和调度算法,异常情况的处理过程。实验表明,混合结构的视频网格具有较好的性能,能够降低区域服务器负载的波动范围。     

全景视频的信息组织和实现方法

全景视频不是一般意义的虚拟现实，它提供了一种新型的时空信息组织形式。这种基于实景图像的全景视频，具有广阔的应、用前景和研究价值．本文介绍了全景视频的概念和表现方式，以及利用全景视频技术来构造虚拟现实环境的方法，并提出了实现全景视频的具体方法步骤。     

The instructional benefits of dynamic visualizations in the acquisition of basketball tactical actions

Recent studies exploring the effects of dynamic visualizations on learning compared with static visualizations have yielded mixed results. Procedural motor learning is one of the few fields in which dynamic representations have shown to be effective. Many of the studies have suggested that this advantage is mainly due to the activation of the “mirror‐neuron system.” This study explores this explanation in physical education domain and analysed the effects of instructional media (video vs. photographs), showing tactical actions in basketball, on learning outcomes (i.e., game understanding and game performance), cognitive load (i.e., mental effort invested and estimated difficulty), and attitudes (i.e., attention, enjoyment, engagement, and challenge) in secondary school students. For all of the indicators, the results show that learning from video was more effective than learning from photographs. These findings have implications for the effective design of instructional media and provide confirmation of the superiority of video for teaching tactical actions involving the entire body.     

Time,engagement and video games: How game design elements shape the temporalities of play in massively multiplayer online role-playing games

Researchers and developers constantly seek novel ways to create engaging applications that are able to retain their users over the long term, make them desire to spend time using the application or go back to using it after a break. With this aim, video games can be an insightful source of inspiration, as they are specifically designed to maximise playing time, increase players' intentions of playing during the day or enhance their willingness to replay. In a gaming context, ‘time’ is an important factor for engagement because game designers can design the game time to retain players in the game environment. Drawing on social practice theory, which is increasingly used in Information Systems (IS) research, I conducted an ethnographic study in World of Warcraft (WoW) to understand how various temporalities are produced within a video game and the effects that they have on players' engagement. The findings show that game temporalities stem from the complex interaction between the design features of the game and the norms, routines and expectations that are part of the game practices. Moreover, these temporalities can engender temporal experiences that may stimulate engagement in various ways. The study contributes to IS literature by proposing a novel understanding of how time can be intentionally designed to sustain user engagement. Finally, it suggests that ‘time design’ in video games could inspire designs in broader IS contexts, such as in the gamification of online communities, crowdsourcing platforms and crowd working systems.     

中国传统五色在现代影视中的情感表现

色彩作为一种影视要素、一种感情载体,在影视作品中起着重要作用。中国传统的色彩观念不仅仅表现于艺术的审美创造,同时又具有象征、寓意等。文章通过中国古典色彩中"五色观"的角度分析一些现代优秀影视作品色彩感情,对影视色彩情感表现上进行深层次的思考、探索。     

基于自由立体视频的露天开采虚拟现实的研究与实现

文章结合最新的交互式自由立体视频技术与露天开采虚拟现实技术,设计并实现了一种基于自由立体视频的露天矿开采虚拟现实技术的交互与演示系统。文章利用3DS Max和VRMap软件建立了某露天矿区的虚拟视觉模型,并将这些虚拟视觉模型按照适合立体显示的条件进行场景渲染和视频图象生成,最后结合虚拟场景的三维显示特性设计了交互式自由立体视频软件,通过该软件展示了虚拟现实场景。该系统克服了传统虚拟现实演示的局限性,用较低的成本支持更多的用户进行参与和交互,同时也具有较强的环境拓展性。     

影像装置艺术的交互模式研究

影像装置艺术是新媒体艺术中影像与装置艺术的综合形态,是科技前沿与现实生活相结合的重要艺术形式。本文以近年来新媒体影像装置的相关作品为例,探索了数字时代影像装置艺术的交互模式类型。作者指出：随着宽带网络、云计算和各种体感交互设备的出现,以动作感应或动态捕捉为基础的影像装置已成为当前主流的新媒体影像装置的表现形式。同时,随着技术手段的多样性,交互影像装置的发展也呈现出更为多元化的趋势。影像装置作品的丰富性、趣味性、观念性和观众的参与度将成为未来决定作品成败的关键。     

VR全景视频传输研究进展

VR全景视频作为一种沉浸式虚拟现实技术,其高分辨率及低延迟的严格要求为视频传输带来了严峻挑战。全景视频传输在全景视频的系统构建中起到了关键作用,并与其他重要技术紧密衔接。为了分析全景视频传输的研究现状和发展趋势,首先对映射格式、视频编码、质量评估等全景视频传输相关技术进行阐述,从不同视角对相关研究领域和方法进行分类归纳。而后详细探讨了全景视频传输技术的传输协议、三类主要传输方法及视口预测,并对各部分梳理了一些比较具有代表性的研究方法。最后就关键性技术对全景视频传输的未来研究进行展望,旨在为研究人员快速全面了解该领域提供帮助。     

一种大视差场景下的实时视频拼接系统

随着虚拟现实技术和视频直播技术的发展,全景视频直播受到广泛的关注。传统的全景产品在处理大视差场景时易发生图像畸变,且难以兼顾实时性要求。为了解决这些问题,设计一种两路视频拼接系统。首先建立拼接背景模型。然后结合ORB(Oriented FAST and Rotated BRIEF)和基于移动DLT(Direct Linear Transformation)的APAP（As-Projective-As-Possible）算法完成图像配准,并改进一种基于最小能量检测的方法寻找最优接缝以避免移动前景引起的鬼影和错位。最后通过拼接模型计算阶段所得的参数索引表,对重叠区域进行融合完成视频帧的实时拼接。实验结果表明该系统可以处理大视差场景,具有良好的实时拼接效果。     

流媒体技术及视频捕获和预览的研究

介绍了流媒体技术和原理，详述了流式传输和传输的过程，以及支持流媒体传输的协议。结合实际阐述了一个能将标准模拟视频信号实时采集存储到硬盘上，并且可以完成预览功能的视频捕获系统。通过capDlgVideoCompression(hwnd)函数显示压缩驱动程序对话框，然后按用户对图像质量和输出文件大小的不同要求可以选择一个已安装的压缩驱动程序，输出不同格式的视频文件。系统的实现过程首先是对imager32视频流捕获卡的开发，然后实现捕获和预览功能的用户级的VC 应用程序的开发。试验证明，该系统能够实现将输入的模拟信号捕获并以文件的形式存储在硬盘上，同时也实现了对输入模拟视频信号的预览功能，图像显示清晰、流畅。     

Utility-oriented resource allocation for 360-degree video transmission over heterogeneous networks

Immersive media streaming, especially virtual reality (VR)/360-degree video streaming which is very bandwidth demanding, has become more and more popular due to the rapid growth of the multimedia and networking deployments. To better explore the usage of resource and achieve better video quality perceived by users, this paper develops an application-layer scheme to jointly exploit the available bandwidth from the LTE and Wi-Fi networks in 360-degree video streaming. This newly proposed scheme explores the saliency of video contents, prediction of users' view and channel status information to maximize the system's utility in a multi-RAN environment. It also determines the optimal association of users with multiple Wi-Fi access points (APs). Besides, a novel buffer strategy is proposed to mitigate the influence of short-time prediction problem for transmitting 360-degree videos in time-varying networks. The promising performance and low complexity of the proposed scheme and algorithms are validated in simulations with various 360-degree videos.     

一种基于模型方法的三维数字影像生成系统

虚拟现实（ＶＲ）已成为计算机图形学中的一个重要分支,它作为一种新兴媒体,从八十年代末开始受到普遍关注,并已在多个领域发挥出色。本文主要介绍一种基于模型的３Ｄ数字影像生成系统。通过多路摄像机记录真实世界中的人物或情景,并提取数字信息,结合标准的计算机图形方法重现原始的三维景物。     

Caching video objects: layers vs versions?

Because Internet access rates are highly heterogeneous, many video content providers today make available different versions of the videos, with each version encoded at a different rate. Multiple video versions, however, require more server storage and may also dramatically impact cache performance in a traditional cache or in a CDN server. An alternative to versions is layered encoding, which can also provide multiple quality levels. Layered encoding requires less server storage capacity and may be more suitable for caching; but it typically increases transmission bandwidth due to encoding overhead. In this paper we compare video streaming of multiple versions with that of multiple layers in a caching environment. We examine caching and distribution strategies that use both versions and layers. We consider two cases: the request distribution for the videos is known a priori; and adaptive caching, for which the request distribution is unknown. Our analytical and simulation results indicate that mixed distribution/caching strategies provide the best overall performance.A shorter version of this work has appeared in Proc. of IEEE International Conference on Multimedia and Expo (ICME), Vol. 2, pages 45–48, Lausanne, Switzerland, August 2002     

PRNU Extraction from Stabilized Video: A Patch Maybe Better than a Bunch

This paper presents an algorithm to solve the problem of Photo-Response Non-Uniformity (PRNU) noise facing stabilized video. The stabilized video undergoes in-camera processing like rolling shutter correction. Thus, misalignment exists between the PRNU noises in the adjacent frames owing to the global and local frame registration performed by the in-camera processing. The misalignment makes the reference PRNU noise and the test PRNU noise unable to extract and match accurately. We design a computing method of maximum likelihood estimation algorithm for extracting the PRNU noise from stabilized video frames. Besides, unlike most prior arts tending to match the PRNU noise in whole frame, we propose a new patch-based matching strategy, aiming at reducing the influence from misalignment of frame the PRNU noise. After extracting the reference PRNU noise and the test PRNU noise, this paper adopts the reference and the test PRNU overlapping patch-based matching. It is different from the traditional matching method. This paper conducts different experiments on 224 stabilized videos taken by 13 smartphones in the VISION database. The area under curve of the algorithm proposed in this paper is 0.841, which is significantly higher than 0.805 of the whole frame matching in the traditional algorithm. Experimental results show good performance and effectiveness the proposed strategy by comparing with the prior arts.     

基于FPGA高清视频图像的光纤传输系统研究

光线应用数据传输是对传统数据传输方式的颠覆,可以对当前的高清视频传输起到重要的现实作用.本文根据FPGA存在的特点设计管线传输系统,重点解决传统背景下远距离视频传输中遇到的问题,在分析系统基本原理基础上,重点设计发送端以及接收端,最后通过简单的条纹实验验证系统设计效果.     

基于实时流媒体技术的全景视频系统

将实时视频采集和虚拟现实技术相结合,探索出一种利用相对经济的采集设备,生成高信息量、强沉浸感的数字媒体的方案。文中介绍了软件系统的设计和实现,并详细说明了系统实现使用的关键技术和相应算法,解决了将流媒体技术与虚拟现实技术相结合的多个难点。全景视频系统系统基于C/S结构在Windows平台上实现,主要利用微软的DirectShow和D3D的开发包,为以后视频会议、数字媒体系统等提供了新的应用前景。