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  • Treadmill

    2017-02-27 15:42:06
    The You'reFat treadmill company has decided to enhance its treadmills to allow users to run workout programs from an audio program (either online streaming audio or from a CD). The program will have ...
  • 这将使treadmill 。 无业游民的开发设置 先决条件 安装Vagrant的 vagrant plugin install vagrant-vbguest 流浪汉设置 克隆库。 克隆库。 运行以下命令 cd treadmill git checkout standard_setup vagrant up ...
  • 提供了一系列内容,Emberella Treadmill呈现最小数量的子列表,以填充滚动区域的可见部分。 随着客户的滚动,这些子列表会适当地“回收”(重新定位并重新绘制新内容),以产生长而连续滚动列表的错觉。 例如,我...
  • Treadmill System Based on Kinect
  • Best Treadmill-crx插件

    2021-04-01 18:56:28
    语言:English 购买最好/顶级品牌跑步机支票价格并在线购买。 还阅读了最新的跑步机评论 在美国大多数城市,当地的健身房和健身工作室已经关闭,大部分年度都关闭,迫使许多人转向户外活动,如跑步和骑自行车锻炼汗水...
  • 跑步机.js 让您的网站感觉无穷无尽。 安装 鲍尔 $ bower install treadmill.js Treadmill . run ( ) ; 执照 麻省理工学院 :copyright:
  • 使用 Arduino Mega 2560 板连接 MCS2100-LTS-50W 跑步机控制板和使用 USB 串行链路的 PC。 带有 TKinter GUI 的 Python 用于使用多处理的主控制。 使用简化的串行驱动程序代替 pySerial。
  • Treadmill:通过精确的负载测试和统计推理识别尾延迟来源 摘要 管理请求的尾部延迟已经成为大规模Internet服务的主要挑战之一。 数据中心正在快速发展,服务运营商经常希望对部署的软件和生产硬件配置进行更改。 ...

    题目:

    Treadmill:通过精确的负载测试和统计推理识别尾延迟来源

    摘要

    管理请求的尾部延迟已经成为大规模Internet服务的主要挑战之一。 数据中心正在快速发展,服务运营商经常希望对部署的软件和生产硬件配置进行更改。 这种变化需要对对服务的影响,特别是其对尾部延迟的影响(例如,服务的响应延迟的95%或99%)的理解。 评估对尾部的影响是具有挑战性的,因为其固有的变异性。用于测量这些影响的现有工具和方法存在许多缺陷,包括差的负载测试仪设计,统计上不准确的聚合和不正确的效应归因。 如文中所示,这些陷阱常常会导致误导性的结论。

    在本文中,我们为服务器工作负载开发统计性严格的性能评估和性能因素归因的方法。首先,我们发现服务器负载测试器的仔细设计可以确保高质量的性能评估,并且经验性地证明了负载测试人员在以前的工作中的不准确性。从先前的工作中学习设计,我们设计和开发了一个模块化负载测试平台,跑步机,克服了现有工具的缺陷。接下来,利用跑步机,我们构建可以适当归因于性能因素的测量和分析程序。我们依靠统计学上的性能评估和分位数回归,将其扩展到适应服务器系统的特性。最后,我们使用增强的方法来评估通用服务器硬件功能与生产硬件上的Facebook生产负载的影响。我们根据请求尾部延迟分解这些特征的影响,并表明我们的评估方法提供了优异的结果,特别是在捕获复杂和反直觉的性能行为方面。通过调整归因建议的硬件特性,我们将第99百分位数延迟减少了43%,差异减少了93%。

    前言

    减少尾部延迟(即延迟分布的高分位数)提高了大规模互联网服务的服务质量[1]。 高尾延迟已被确定为现代数据中心设计面临的主要挑战之一,因为它导致用户体验不佳,特别是对于诸如网络搜索和社交网络之类的交互式服务。这些服务由机群集群供电,其中单个请求以“扇出”模式分布在大量服务器之间。 在这种设计中,这种系统的整体性能取决于响应速度最慢的机器[2]。 最近的工作试图控制和理解这些尾部请求,无论是在个别服务器还是整个集群级别[3]

    对于数据中心运营商来说,精确测量尾部延迟而不会中断生产系统的能力很重要,原因有很多。首先,服务器通常大量(例如每次1000s)获取,因此选择最佳设计并仔细提供资源很重要。 评估硬件配置需要对提高的工作负载进行大量和准确的测量。第二,有必要在不破坏生产系统的情况下,忠实地测量效能。 软件和硬件变化的高频率使得评估这些生产变化非常困难或不可能,因为它可以很容易地导致用户可见的事件。 相反,最好在安全但准确的负载测试环境中了解性能关键决定的影响。

    构建这样的负载测试环境以实现精确的尾部延迟测量是特别具有挑战性的。这主要是因为与传统的单服务器工作负载(例如SPEC CPU2006PARSEC)相比,大规模Internet服务工作负载(例如,分布式服务器端软件,网络连接等)所涉及的系统和资源显着增加。 尽管已经有几个以前的工作[4,5,6,7,8,9,10]试图弥合这个差距,但是在他们的负载测试设计中有几个陷阱,我们将在后面的文章中给出。 不幸的是,这些工具通常用于研究出版物进行评估,陷阱可能导致误导性的结论。类似于学术界,工业界还缺乏准确的尾部延迟测量测试台,导致不必要的资源过度供应[11]和不明原因的性能回归[12]

    此外,为了能够控制这些互联网服务的尾部延迟,需要彻底和正确地理解尾部延迟的来源。这些互联网服务与广泛的系统和资源(包括操作系统,网络堆栈和服务器硬件)进行交互,从而定量地将尾部延迟来源归因于个人资源的能力是至关重要的。 虽然以前的一些作品[13,14,15,16,3,17,18,19,20,21,22,23,24,25]研究了个别资源对尾部潜伏期的影响,但许多资源复杂的相互作用行为,无法在孤立的研究中被捕获。 例如,Turbo BoostDVFS调速器可以通过竞争热余量来间接地相互作用。 请注意,识别尾部延迟源的能力取决于上述第一个挑战。

    换句话说,没有对尾部延迟的精确测量,我们将无法将其正确归因于各种来源。在本文中,我们首先调查研究界使用的现有绩效评估方法。 我们已经确定了这些工具的一组常见错误:

    查询到达后生成 - 负载测试软件通常用于简化软件。 我们发现常用的编程范例创建一个隐式排队模型,其近似于闭环系统,并且系统地低估了尾部延迟。相反,我们展示了精确定时的开环负载测试仪是正确运行系统排队行为所必需的。

    统计汇总 - 由于请求率高,必须采用采样来控制测量开销。必须仔细执行这些延迟样本的在线聚合。我们发现,单数统计(例如,第9599个周期延迟的点估计)不能捕获详细信息;其他负载测试仪中使用的静态直方图也表现出偏差。
       
    •客户端排队偏差 - 由于许多商业系统中的高吞吐率(每秒100k-1M的请求),我们证明,必须使用多台客户机来测试单个服务器。没有使用轻松的客户端,延迟测量迅速开始受到客户端排队的影响,产生有偏见的结果。
        
    •性能“滞后” - 我们观察到在收集足够数量的样本之后估计的延迟收敛的现象,但是在再次运行负载测试时,测试收敛到不同的值。这是由于底层系统状态的变化,如逻辑内存,线程和连接到物理资源的映射。我们将其称为滞后,因为没有合理数量的附加样本可以使两个运行收敛到同一点。相反,我们发现实验必须重新启动多次,并且收敛的值应该被聚合。

    基于这些见解,本文提出了一种用于精确尾部延迟测量的系统过程,并详细说明了设计选择,使我们能够克服现有方法的缺陷。提出的程序利用模块化软件负载测试仪Treadmill的多个轻量级实例,以避免客户端排队偏差。Treadmill的软件架构保留正确的请求到达之外的时间,并且允许轻松添加新的工作负载,而无需复杂的软件更改。重要的是,它可以适当地聚合客户端的分布,并执行多个独立的实验来减轻性能滞后的影响。

    通过Treadmill实现的精确测量使得能够识别延迟来自哪里。我们基于最近的分位数回归研究[26],并将尾部延迟归因于导致尾部的各种硬件特征。这允许我们公布系统黑盒子,并更好地了解调整硬件配置对尾部延迟的影响。我们使用运行两个关键Facebook工作负载的Facebook生产硬件进行此评估:普及密钥服务器Memcached和最近公布的软件路由系统mcrouter [27]。使用我们的尾部延迟归因程序,我们能够识别许多反直觉的性能行为,包括不同硬件资源之间的复杂交互,这些交互不能通过孤立的各个硬件功能的先前研究来捕获。最后,我们展示了我们成功捕获了mcrouter系统中90%的性能变化,并为Memcached捕获了95%以上的性能变化。通过仔细调整归因建议的硬件功能,我们将第99百分位数延迟减少了43%,方差99位的百分比减少了93%。

    总之,本文有三个主要贡献:

    •对现有负荷测试方法中常见的陷阱进行调查 - 对相关工作现有方法进行调查,并对其缺点进行实证分析。我们将这些镜子分类为未来从业人员的四大原则。

    精确的基于群集的绩效评估方法 - 我们介绍了一个强大的实验方法的设计,以及作为开源软件发布的软件负载测试工具跑步机。这两个系统都符合我们原则的要求,并且易于扩展以供采纳。

    归因于尾部延迟的来源 - 通过我们的方法实现的高精度测量使得可以使用分位数回归来理解尾部延迟方差的来源。我们成功地将大部分方差归因于几个高级硬件特征及其间的相互作用。通过仔细调整归因结果推荐的硬件配置,我们显着降低了尾部延迟及其差异。

    现代艺术方法论中的讽刺

    为了了解评估试验台的要求,我们首先调查了以前工作中现有的方法和工具。许多工具可用于研究服务器端软件的性能,包括YCSB [4]Faban[28]Mutilate [29]CloudSuite[6]。 这些工具已经广泛应用于标准的基准套件,包括SPEC2010 jEnterprise [30]SPEC2011 SIP基础设施[31]CloudSuite [6]BigDataBench [8],从而引起了许多最近发表的研究项目。

    通过研究这些现有工具,我们发现了几个常见的陷阱。我们将它们分为以下四个主题。

    A.查询到达后生成

    性能评估测试台需要一个负载测试器,一个以受控的方式向服务器发出请求的软件。客户机将运行负载测试器,周期性地构建,发送和接收请求以实现期望的吞吐量。通常采用两种类型的控制回路来创建这些定时:开环控制和闭环控制[32]。闭环控制器具有反馈回路,其中仅在已经接收到对先前请求的响应之后才尝试发送另一个请求。相比之下,开环控制器在定义的时间内发送请求,而不管响应的状态如何。几乎所有的现代数据中心服务器端软件都是为了处理开环设置而建立的,所以每个服务器线程在忙碌处理之前都不会拒绝来自客户端的请求。

    然而,由于软件的简单性,许多负载测试仪被实现为闭环控制器,包括FabanYCSBMutilate,如表I所示。通常,使用发出网络请求时阻止的工作线程生成负载。然后可以通过增加或减少负载发生器中的螺纹量来控制负载量。不幸的是,这种模式完全类似于闭环控制器;每个线程正好代表一个潜在未完成的请求

    B.统计汇总
       
    由于请求率高,负载测试软件需要至少执行一些延迟样本的统计汇总,以避免保持大量样本的开销。我们发现在这个过程中必须小心,可能会发生两种类型的错误。首先,负载测试人员必须保持随时间变化的延迟内部直方图。那些维护直方图的负载测试仪常常会导致静态设置直方图桶的错误。当服务器被高度利用时,非自适应直方图分组将会中断,因为延迟在达到稳定状态之前会保持增加,从而超过直方图的上限。
       
    此外,如果请求具有不同的特征(例如,不同的请求类型,由不同的机器发送等),我们观察到由于不正确的统计聚合而可能发生偏差。例如,在图2中,我们演示了一种场景,其中四个客户端用于将请求发送到同一个Memcached服务器,“客户端1”位于与其他客户端和服务器不同的机架上。在x轴上的每个延迟点,每个阴影区域表示来自四个客户端之一的样本的比例。随着分数量的增加,人们可以清楚地看到,大多数样本来自“客户端1”。这种偏差是有问题的,因为系统的性能估计成为一个单一客户端的功能。相反,应该单独提取每个客户端的感兴趣度量(例如,第99百分位数延迟),并将其合理聚合。

        C.客户端排队偏差
       
    在操作负载测试器时,纯粹测量服务器端延迟的影响很重要。对于服务时间长(例如,复杂的MySQL查询)的工作负载,客户端不必发出许多使服务器饱和的请求。然而,对于像Memcached这样的工作负载,客户端和网络本身的请求率相当高。这可能导致客户端和网络本身的排队效应,从而偏差延迟测量。 YCSBCloudSuite由于其单个客户端配置而受到这样的偏见,如表I所示。
        
    3显示了客户端和网络利用率如何对延迟测量进行偏差的示例。在“单客户端安装”中,客户端和网络具有与服务器相同的利用率。可以看出,客户端延迟和网络延迟随着服务器利用率的增加而增长,并且在端对端延迟中占有重要的比例。
    我们发现设计一个可以使服务器充分饱和的单客户端负载测试器是非常具有挑战性的,即使不是不可能,也不会对以微秒级延迟运行的现代数据中心工作负载造成重大的客户端排队。相反,有必要建立一个多客户机,并且拥有足够数量的机器,使得客户端和网络延迟保持较低。在“MultiClient Setup”中,我们增加了客户端计算机的数量以最小化这些偏差。经过调整后,大部分测量的延迟来自服务器。

    D.性能“迟滞”

    4.差异存在,而不管单个运行的样本大小。单次运行对于小样本量(即,运行早期)表现出很大的变化。具有足够大的样本量,第99百分位数延迟的估计收敛。 然而,从经验上我们发现每个运行都可以收敛到一个不同的值。 虽然每次运行的测试程序都会产生紧密的间隔,每次运行的结果明显变化(与平均值相差15-67%)。
       
    通过实验,我们发现一个通常的行为,如何估计收敛,我们称之为性能“迟滞”。图4表明,随着更多样本的收集,第99百分位延迟的估计开始收敛到一个奇异值。但是,如果重新启动服务器并执行另一个运行,则估计可以收敛到不同的值。
       
    在这种情况下,估计的样本量很大,我们预计每个估计值的“确定”都很高,但显然在运行中仍然存在差异。事实上,这些估计与平均值的差异高达67%。这种现象意味着只能通过“运行更长时间”来实现更高的统计准确度,并且与STABILIZER[33]中观察到的效果相似。相反,有必要多次重新启动整个过程并聚合结果。然而,现有的负载测试仪都没有足够的足够强大来处理这种情况,如表I所示。


    注:内容太多,只有1、2章节,我的操作系统课程作业。



    展开全文
  • Virtual reality

    千次阅读 2016-08-08 09:57:07
    转自:...Virtual reality From Wikipedia, the free encyclopedia “Virtuality” redirects here. For other uses, see Virtuality (disambiguation)....Not to be confus

    转自:https://en.wikipedia.org/wiki/Virtual_reality
    Virtual reality
    From Wikipedia, the free encyclopedia
    “Virtuality” redirects here. For other uses, see Virtuality (disambiguation).
    Not to be confused with Simulated reality.

    This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)
    This article needs additional citations for verification. (December 2010)
    This article possibly contains original research. (December 2010)

    Virtual reality or virtual realities (VR), also known as immersive multimedia or computer-simulated reality, is a computer technology that replicates an environment, real or imagined, and simulates a user’s physical presence and environment to allow for user interaction. Virtual realities artificially create sensory experience, which can include sight, touch, hearing, and smell.

    Most up-to-date virtual realities are displayed either on a computer monitor or with a virtual reality headset (also called head-mounted display), and some simulations include additional sensory information and focus on real sound through speakers or headphones targeted towards VR users. Some advanced haptic systems now include tactile information, generally known as force feedback in medical, gaming and military applications. Furthermore, virtual reality covers remote communication environments which provide virtual presence of users with the concepts of telepresence and telexistence or a virtual artifact (VA) either through the use of standard input devices such as a keyboard and mouse, or through multimodal devices such as a wired glove or omnidirectional treadmills. The immersive environment can be similar to the real world in order to create a lifelike experience—for example, in simulations for pilot or combat training—or it can differ significantly from reality, such as in VR games.

    Contents

    1 Concept origins
    2 History
        2.1 Before the 1950s
        2.2 1950–1970
        2.3 1970–1990
        2.4 1990–2000
        2.5 2000–present
    3 Use
        3.1 Education and training
            3.1.1 Training
        3.2 Video games
        3.3 Fine arts
        3.4 Heritage and archaeology
        3.5 Architectural design
        3.6 Urban design
        3.7 Therapy
        3.8 Theme parks
        3.9 Concerts
        3.10 Retail
        3.11 Charity
        3.12 Film
        3.13 Media
        3.14 Pornography
    4 In fiction
        4.1 Motion pictures
    5 Concerns and challenges
    6 Pioneers and notables
    7 Commercial industries
    8 See also
    9 Notes
    10 References
        10.1 General references
        10.2 Inline citations
    11 External links
    

    Concept origins

    In 1938, Antonin Artaud described the illusory nature of characters and objects in the theatre as “la réalité virtuelle” in a collection of essays, Le Théâtre et son double. The English translation of this book, published in 1958 as The Theater and its Double,[1] is the earliest published use of the term “virtual reality”.

    The term “artificial reality”, coined by Myron Krueger, has been in use since the 1970s. The term “Virtual Reality” was used in The Judas Mandala, a 1982 science-fiction novel by Damien Broderick. The Oxford English Dictionary cites a 1987 article titled “Virtual reality”,[2] but the article is not about VR technology. Virtual Reality in its modern usage was popularized by Jaron Lanier through his company VPL Research. VPL Research held many of the mid eighties VR patents, and they developed the first widely used HMD: EyePhone and Haptic Input DataGlove[3] The concept of virtual reality was popularized in mass media by movies such as Brainstorm and The Lawnmower Man. The VR research boom of the 1990s was accompanied by the non-fiction book Virtual Reality (1991) by Howard Rheingold.[4] The book served to demystify the subject, making it more accessible to less technical researchers and enthusiasts.
    History
    Before the 1950s
    The Sensorama was released in the 1950s.
    View-Master, a stereoscopic visual simulator, was introduced in 1939.

    The first traces of virtual reality came from the world of science fiction. Stanley G. Weinbaum’s 1935 short story “Pygmalion’s Spectacles” [5] is recognized as one of the first works of science fiction that explores virtual reality. It describes a goggle-based virtual reality system with holographic recording of fictional experiences including smell and touch.
    1950–1970

    Morton Heilig wrote in the 1950s of an “Experience Theatre” that could encompass all the senses in an effective manner, thus drawing the viewer into the onscreen activity. He built a prototype of his vision dubbed the Sensorama in 1962, along with five short films to be displayed in it while engaging multiple senses (sight, sound, smell, and touch). Predating digital computing, the Sensorama was a mechanical device, which reportedly still functions today. Around the same time, Douglas Engelbart used computer screens as both input and output devices.

    In 1968, Ivan Sutherland, with the help of his student Bob Sproull, created what is widely considered to be the first virtual reality and augmented reality (AR) head-mounted display (HMD) system. It was primitive both in terms of user interface and realism, and the HMD to be worn by the user was so heavy that it had to be suspended from the ceiling. The graphics comprising the virtual environment were simple wire-frame model rooms. The formidable appearance of the device inspired its name, The Sword of Damocles.
    1970–1990
    Battlezone, an arcade video game from 1980, used 3D vector graphics to immerse the player in a VR world.(Atari).

    Also notable among the earlier hypermedia and virtual reality systems was the Aspen Movie Map, which was created at MIT in 1978. The program was a crude virtual simulation of Aspen, Colorado in which users could wander the streets in one of three modes: summer, winter, and polygons. The first two were based on photographs—the researchers actually photographed every possible movement through the city’s street grid in both seasons—and the third was a basic 3-D model of the city.

    Atari founded a research lab for virtual reality in 1982, but the lab was closed after two years due to Atari Shock (North American video game crash of 1983). However, its hired employees, such as Tom Zimmerman, Scott Fisher, Jaron Lanier and Brenda Laurel, kept their research and development on VR-related technologies.

    By the 1980s the term “virtual reality” was popularized by Jaron Lanier, one of the modern pioneers of the field. Lanier had founded the company VPL Research in 1985. VPL Research has developed several VR devices like the Data Glove, the Eye Phone, and the Audio Sphere.VPL Research authorized the warrant of the Data Glove to New York video game company Mattel. Mattel used this technology and made an accessory known as the Power Glove. It was hard to use and not popular at all. However, the price for this accessory was $75. It might be the earliest affordable VR device.

    During this time, virtual reality was not well known, though it did receive media coverage in the late 80s. Most of its popularity came from marginal cultures, like cyberpunks, who viewed the technology as a potential means for social change, and drug culture, who praised virtual reality not only as a new art form, but as an entirely new frontier.[6] Once the industry began to attract media coverage, people started realizing that potential. Some even compared the innovations in virtual reality to the Wright Brothers’ pioneering invention of the airplane.[7]

    In 1990, Jonathan Waldern, a VR Ph.D, demonstrates “Virtuality” at the Computer Graphics 90 exhibition staged at London’s Alexandra Palace. This new system was an arcade machine that would use a virtual reality headset to immerse players.

    CyberEdge and PCVR, VR industry focused magazines, started to publish in the early 90s. However, most ideas about VR remained theoretical due to the limited computing power available at the time. The extremely high cost of the technology made it impossible for most consumers to adopt. The public turned their focus to the Internet after it came out. The VR industry went silent in the U.S. and only provided VR devices for medical, flight simulation, automobile industry design, and military training purposes.
    1990–2000
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    In 1991, Sega announced the Sega VR headset for arcade games and the Mega Drive console. It used LCD screens in the visor, stereo headphones, and inertial sensors that allowed the system to track and react to the movements of the user’s head.[8]

    In the same year, Virtuality launched and went on to become the first mass-produced, networked, multiplayer VR entertainment system. It was released in many countries, including a dedicated VR arcade at Embarcadero Center in San Francisco. Costing up to $73,000 per multi-pod Virtuality system, they featured headsets and exoskeleton gloves that gave one of the first “immersive” VR experiences.[9]

    Antonio Medina, a MIT graduate and NASA scientist, designed a virtual reality system to “drive” Mars rovers from Earth in apparent real time despite the substantial delay of Mars-Earth-Mars signals. The system, termed “Computer-Simulated Teleoperation” as published by Rand, is an extension of virtual reality.[10]

    In 1991, Carolina Cruz-Neira, Daniel J. Sandin and Thomas A. DeFanti from the Electronic Visualization Laboratory created the first cubic immersive room, replacing goggles by a multi-projected environment where people can see their body and other people around.

    In 1991, Computer Gaming World predicts “Affordable VR by 1994”.[11]

    By 1994, Sega released the Sega VR-1 motion simulator arcade attraction,[12][13] in SegaWorld amusement arcades. It was able to track head movement and featured 3D polygon graphics in stereoscopic 3D, powered by the Sega Model 1 arcade system board.[14]

    Also in 1994 Apple released QuickTime VR. A widely available product for interacting with VR models.

    A year later, the artist Maurice Benayoun created the first VR artwork connecting in real time 2 continents: the “Tunnel under the Atlantic” between the Pompidou Centre in Paris and the Museum of Contemporary Art in Montreal. The installation included dynamic real time 3d modeling, video chat, spatialized sound and AI content management.

    The Virtual Boy was created by Nintendo and was released in Japan on July 21, 1995 and in North America on August 15, 1995.[15]

    Also in 1995, a group in Seattle created public demonstrations of a “CAVE-like” 270 degree immersive projection room called the Virtual Environment Theater, produced by entrepreneurs Chet Dagit and Bob Jacobson.[16] Then in 1996 the same system was shown in tradeshow exhibits sponsored by Netscape Communications, and championed by Jim Barksdale, for the first time showing VR connected to the Internet with World Wide Web content feeds embedded in VRML 3D virtual world models.

    Forte released the VFX1, a PC-powered virtual reality headset in 1995, which was supported by games including Descent, Star Wars: Dark Forces, System Shock and Quake.

    In 1999, entrepreneur Philip Rosedale formed Linden Lab with an initial focus on the development of hardware that would enable computer users to be fully immersed in a 360 degree virtual reality experience. In its earliest form, the company struggled to produce a commercial version of “The Rig,” which was realized in prototype form as a clunky steel contraption with several computer monitors that users could wear on their shoulders.[17] That vision soon morphed into the software-based, 3D virtual world Second Life.
    A 2013 developer version of Oculus Rift from Oculus VR, a company Facebook acquired in 2014 for $2 billion
    Another VR headset called the “HTC Vive” Developed in co-production between HTC and Valve Corporation.
    2000–present
    The affordable and accessible Google Cardboard standard.

    In 2001, SAS3 or SAS Cube became the first PC based cubic room, developed by Z-A Production (Maurice Benayoun, David Nahon), Barco, Clarté, installed in Laval France in April 2001. The SAS library gave birth to Virtools VRPack.

    By 2007, Google introduced Street View, a service that shows panoramic views of an increasing number of worldwide positions such as roads, indoor buildings and rural areas. It also features a stereoscopic 3D mode, introduced in 2010.[18]

    In 2010, Palmer Luckey, who later went on to found Oculus VR, designed the first prototype of the Oculus Rift. This prototype, built on a shell of another virtual reality headset, displayed only 2-D images and was noticeably cumbersome to wear. However, it boasted a 90-degree field of vision that was previously unseen anywhere in the market at the time. This initial design would later serve as a basis from which the later designs came.[19]

    In 2013, Nintendo filed a patent for the concept of using VR technology to produce a more realistic 3D effect on a 2D television. A camera on the TV tracks the viewer’s location relative to the TV, and if the viewer moves, everything on the screen reorients itself appropriately. “For example, if you were looking at a forest, you could shift your head to the right to discover someone standing behind a tree.”[20]

    In July 2013, Guild Software’s Vendetta Online was widely reported as the first MMORPG to support the Oculus Rift,[21][22] making it potentially the first persistent online world with native support for a consumer virtual reality headset.

    On March 25, 2014, Facebook purchased a company that makes virtual reality headsets, Oculus VR, for $2 billion.[23] Sony announces Project Morpheus (its code name for PlayStation VR), a virtual reality headset for the PlayStation 4.[24] Google announces Cardboard, a do-it-yourself stereoscopic viewer for smartphones.

    Since 2013, there have been several virtual reality devices that seek to enter the market to complement Oculus Rift to enhance the game experience. One, Virtuix Omni, is based on the ability to move in a three dimensional environment through an omnidirectional treadmill.

    In 2015, the Kickstarter campaign for Gloveone, a pair of gloves providing motion tracking and haptic feedback, was successfully funded, with over $150,000 in contributions.[25]

    In February–March 2015, HTC partnered with Valve Corporation announced their virtual reality headset HTC Vive and controllers, along with their tracking technology called Lighthouse, which utilizes “base stations” mounted to the wall above the user’s head in the corners of a room for positional tracking of the Vive headset and its motion controllers using infrared light.[26][27][28][29] The company announced its plans to release the Vive to the public in April 2016 on December 8, 2015.[30][31] Units began shipping on April 5, 2016.[32]

    In July 2015, OnePlus became the first company to launch a product using virtual reality.[33] They used VR as the platform to launch their second flagship device the OnePlus 2, first viewable using an app on the Google Play Store,[34] then on YouTube.[35] The launch was viewable using OnePlus Cardboard, based on the Google’s own Cardboard platform. The whole VR launch had a runtime of 33 minutes, and was viewable in all countries.

    Also in 2015, Jaunt, a startup company developing cameras and a cloud distribution platform, whose content will be accessible using an app, reached $100 million in funding from such sources as Disney and Madison Square Garden.[36]

    On April 27, 2016, Mojang announced that Minecraft is now playable on the Gear VR.[37] Minecraft is still being developed for the Oculus Rift headset but a separate version was released to the Oculus Store for use with the Gear VR. This version has everything that’s in the Pocket Edition of Minecraft.
    Use
    Education and training

    Few are creating content that may be used for educational purposes, with most advances being made in the entertainment industry, yet research is being done on learning in virtual reality as many believe its immersive qualities have the potential to enhance learning.
    Training
    U.S. Navy personnel using a VR parachute training simulator.

    The usage of VR in a training perspective is to allow professionals to conduct training in a virtual environment where they can improve upon their skills without the consequence of failing the operation. Thomas A. Furness III was one of the first to develop the use of VR for military training when, in 1982, he presented the Air Force with his first working model of a virtual flight simulator he called the Visually Coupled Airborne Systems Simulator (VCASS). By the time he started his work on VCASS, aircraft were becoming increasingly complicated to handle and virtual reality provided a better solution to previous training methods. Furness attempted to incorporate his knowledge of human visual and auditory processing to create a virtual interface that was more intuitive to use. The second phase of his project, which he called the “Super Cockpit,” was even more advanced, with high resolution graphics (for the time) and a responsive display. Furness is often credited as a pioneer in virtual reality for this research.[6]

    VR plays an important role in combat training for the military. It allows the recruits to train under a controlled environment where they are to respond to different types of combat situations. A fully immersive virtual reality that uses head-mounted display (HMD), data suits, data glove, and VR weapon are used to train for combat. This setup allows the training’s reset time to be cut down, and allows more repetition in a shorter amount of time. The fully immersive training environment allows the soldiers to train through a wide variety of terrains, situations and scenarios.[38]

    VR is also used in flight simulation for the Air Force where people are trained to be pilots. The simulator would sit on top of a hydraulic lift system that reacts to the user inputs and events. When the pilot steer the aircraft, the module would turn and tilt accordingly to provide haptic feedback. The flight simulator can range from a fully enclosed module to a series of computer monitors providing the pilot’s point of view. The most important reasons on using simulators over learning with a real aircraft are the reduction of transference time between land training and real flight, the safety, economy and absence of pollution.[39] By the same token, virtual driving simulations are used to train tank drivers on the basics before allowing them to operate the real vehicle.[40] Finally, the same goes for truck driving simulators, in which Belgian firemen are for example trained to drive in a way that prevents as much damage as possible. As these drivers often have less experience than other truck drivers, virtual reality training allows them to compensate this. In the near future, similar projects are expected for all drivers of priority vehicles, including the police.[41]

    Medical personnel are able to train through VR to deal with a wider variety of injuries.[42] An experiment was performed by sixteen surgical residents where eight of them went through laparoscopic cholecystectomy through VR training. They then came out 29% faster at gallbladder dissection than the controlled group.[43] With the increased commercial availability of certified training programs for basic skills training in VR environments, students have the ability to familiarize themselves with necessary skills in a corrective and repetitive environment; VR is also proven to help students familiarize themselves with skills not specific to any particular procedure.[44]

    VR application was used to train road crossing skills in children. It proved to be rather successful. However some students with autistic spectrum disorders after such training might be unable to distinguish virtual from real. As a result, they may attempt quite dangerous road crossings.[45]
    Video games
    Paramount for the immersion into virtual reality are a high frame rate (at least 95 fps), as well as a low latency. Furthermore, a pixel persistence lower than 3 ms is required to not get sick when moving the head around.

    The use of graphics, sound and input technology in video games can be incorporated into VR. Several Virtual Reality head mounted displays (HMD) were released for gaming during the early-mid 1990s. These included the Virtual Boy developed by Nintendo, the iGlasses developed by Virtual I-O, the Cybermaxx developed by Victormaxx and the VFX1 Headgear developed by Forte Technologies. Other modern examples of narrow VR for gaming include the Wii Remote, the Kinect, and the PlayStation Move/PlayStation Eye, all of which track and send motion input of the players to the game console somewhat accurately.

    Several companies are working on a new generation of VR headsets: Oculus Rift is a head-mounted display for gaming purposes developed by Oculus VR, an American technology company that was acquired for US$2 billion by Facebook in 2014. One of its rivals was named by Sony as PlayStation VR (codenamed Morpheus), which requires a PS4 instead of a PC to run. In 2015, Valve Corporation announced their partnership with HTC to make a VR headset capable of tracking the exact position of its user in a 4.5 by 4.5 meters area, the HTC Vive.[46] All these virtual reality headsets are tethered headsets that use special curved lenses to magnify and stretch a 5.7-inch screen (in the case of Morpheus) across your field of vision. There are many more gaming VR headsets in development, each with its own special abilities. StarVR, for instance, offers a 210° field of view, whereas FOVE tracks the position of your eyes as an input method.[47]
    Fine arts

    David Em was the first fine artist to create navigable virtual worlds in the 1970s.[48] His early work was done on mainframes at Information International, Inc., Jet Propulsion Laboratory, and California Institute of Technology. Jeffrey Shaw explored the potential of VR in fine arts with early works like Legible City (1989), Virtual Museum (1991), and Golden Calf (1994). Canadian artist Char Davies created immersive VR art pieces Osmose (1995) and Ephémère (1998). Maurice Benayoun’s work introduced metaphorical, philosophical or political content, combining VR, network, generation and intelligent agents, in works like Is God Flat? (1994), “Is the Devil Curved?” (1995), The Tunnel under the Atlantic (1995), and World Skin, a Photo Safari in the Land of War (1997). Other pioneering artists working in VR have include Luc Courchesne, Rnmnmita Addison, Knowbotic Research, Rebecca Allen, Perry Hoberman, Jacki Morie, Margaret Dolinsky and Brenda Laurel. All mentioned artists are documented in the Database of Virtual Art.[49]
    Heritage and archaeology

    The first use of a VR presentation in a heritage application was in 1994, when a museum visitor interpretation provided an interactive “walk-through” of a 3D reconstruction of Dudley Castle in England as it was in 1550. This consisted of a computer controlled laserdisc-based system designed by British-based engineer Colin Johnson. The system was featured in a conference held by the British Museum in November 1994, and in the subsequent technical paper, Imaging the Past – Electronic Imaging and Computer Graphics in Museums and Archaeology.[50]

    Virtual reality enables heritage sites to be recreated extremely accurately, so that the recreations can be published in various media.[51] The original sites are often inaccessible to the public or, due to the poor state of their preservation, hard to picture.[52] This technology can be used to develop virtual replicas of caves, natural environment, old towns, monuments, sculptures and archaeological elements.[53]
    Architectural design
    A visitor at Mozilla Berlin Hackshibition trying Oculus Rift virtual reality experience on Firefox.

    One of the first recorded uses of virtual reality in architecture was in the late 80s when the University of North Carolina modeled its Sitterman Hall, home of its computer science department, in a virtual environment.[7]

    Several companies, including IrisVR and Floored, Inc., provide software or services that allow architectural design firms and various clients in the real estate industry to tour virtual models of proposed building designs. IrisVR currently provides software that allows users to convert design files created in CAD programs like SketchUp and Revit into files viewable with an Oculus Rift, HTC Vive, or a smartphone “in one click,” without the need for complex tiered workflows or knowledge of game engines such as Unity3D.[54] Floored, meanwhile, manually constructs and refines Rift-viewable 3D models in-house from either CAD files for un-built designs or physical scans of already built, brick-and-mortar buildings, and provides clients with access to its own viewing software, which can be used with either an Oculus Rift or a standard 2D web browser, afterward.[55]

    VR software products like these can provide a number of benefits to architects and their clients. During the design process, architects themselves can use VR in order to actually experience the designs they are working on before they are built. In particular, seeing a design in VR can help impress upon the architect a correct sense of scale and proportion.[56] Having an interactive VR model on hand also eliminates the need to waste time and resources constructing physical miniatures in order to demonstrate or examine a design concept to clients or the public. Later on, after a building is constructed, developers and owners can create a VR model of a space that allows potential buyers or tenants to tour a space in VR, even if real-life circumstances make a physical tour unfeasible. For instance, if the owner of an apartment building in Manhattan has a VR model of a space while the building is under construction, they can begin showing and renting the units before they are even ready to be occupied. Furthermore, this sort of showing can be conducted over any distance, as long as the potential customer has access to a VR setup (or, even, with the help of Google Cardboard or a similar phone-based VR headset, nothing but an ordinary smartphone.)
    Urban design

    In 2010, 3D virtual reality was beginning to be used for urban regeneration and planning and transport projects.[57]

    In 2007 development began on a virtual reality software which took design coordinate geometry used by land surveyors and civil engineers and incorporated precision spatial information created automatically by the lines and curves typically shown on subdivision plats and land surveying plans. These precise spatial areas cross referenced color and texture to an item list. The item list contained a set of controls for 3D rendering such as water reflective surface or building height. The land surface in software to create a contour map uses a digital terrain model (DTM). By 2010, prototype software was developed for the core technology to automate the process leading from design to virtualization. The first beta users in 2011 were able to press a single function and automatically drape the design or survey data over the digital terrain to create data structures that are passed into a video gaming engine to create a virtual interactive world showing massing of buildings in relation to man made improvements.
    A Coved land development plan using 4th generation design and principals of Prefurbia

    It was the first application where virtual reality was made effortless for Urban Planning principals using technology. The software was improved to implement massing or 3D models from other free or commercially sold software to create more realistic virtual reality with very little time and effort (see the below image). The software is marketed as LandMentor and is the first precision design technology to make Urban Planning widely available with a short learning curve.[citation needed]
    A Coved Streetscape with homes using architectural shaping and blending in Viera Florida
    Therapy
    Main article: Virtual reality therapy

    The primary use of VR in a therapeutic role is its application to various forms of exposure therapy, including phobia treatments.
    Theme parks

    Since 2015, virtual reality has been installed onto a number of roller coasters, including Galactica at Alton Towers, The New Revolution at Six Flags Magic Mountain and Alpenexpress at Europapark, amongst others.
    Concerts

    In Oslo Spektrum on May the 3rd 2016, Norwegian band a-ha cleared away their normal stage-production to give room for a very different concert performance in collaboration with Void, a Norwegian computational design studio working in the intersection between design, architecture, art and technology. The collaboration resulted in a unique one-of-a-kind concert with advanced scenography using 360 virtual reality technology.

    The concept involved several movement sensors that reacted to the bands movements, voices and instruments. 3D cameras, 20000 lines of codes, 1000 square meters of projection film and massive projectors was set up into a visual show that made the Oslo Spektrum arena in Oslo, Norway into a light installation and visual experience that unfolded live for the audience instead of a pre programmed sequence. The stereoscopic VR-experience was made available for Android users directly through a YouTube app and also made available for iPhone users and other platforms.[58][59][60]
    Retail

    Lowe’s, IKEA, and Wayfair have developed systems that allow these company’s products to be seen in virtual reality, to give consumers a better idea of how the product will fit into their home, or to allow the consumer to get a better look at the product from home.[61]
    Charity

    Non-profit organisations such as Amnesty International, UNICEF, and World Wide Fund for Nature (WWF) have started using virtual reality to bring potential supporters closer to their work, effectively bringing distant social, political and environmental issues and projects to members of the public in immersive ways not possible with traditional media. Panoramic 360 views of conflict in Syria[62] and face to face encounters with CGI tigers in Nepal[63] have been used in experiential activations and shared online to both educate and gain financial support for such charitable work.
    Film

    Many companies, including GoPro, Nokia, Samsung, and Nikon, develop omnidirectional cameras, also known as 360-degree cameras or VR cameras, that have the ability to record in all directions.[64] These cameras are used to create images and videos that can be viewed in VR. (See VR photography.) Films produced for VR permit the audience to view the entire environment in every scene, creating an interactive viewing experience.

    Production companies, such as Fox Searchlight Pictures and Skybound, utilize VR cameras to produce films that are interactive in VR. Fox Searchlight, Oculus and Samsung Gear VR collaborated on a project titled “Wild – The Experience”, starring Reese Witherspoon. The VR film was presented at the Consumer Electronics Show as well as the Sundance Film Festival in January 2015.[65]

    On December 8, 2015, the production company Skybound announced their VR thriller titled “Gone”. In collaboration with the VR production company WEVR, and Samsung Gear VR, the 360-degree video series was released on January 20, 2016.[66][67]
    Media

    Companies such as Paramount Pictures, and Disney have applied VR into marketing campaigns creating interactive forms of media.

    In October 2014 Paramount Pictures, in collaboration with the media production company Framestore, created a VR experience utilizing the Oculus DK2. The experience was dubbed a “time sensitive adventure in space” that took place in a portion of the Endurance space ship from the film “Interstellar.” The experience was available to the public at limited AMC theater locations.[68][69]

    In May 2016, Disney released a VR experience titled Disney Movies VR on Valve Corporation’s Steam software, free for download. The experience allows users to interact with the characters and worlds from the Disney, Marvel, and Lucasfilm universes.[70]
    Pornography

    Pornographic studios such as Naughty America and Kink have applied VR into their products since late 2015 or early 2016. The clips and videos are shot from an angle that resembles a POV-style porn.[71][72]
    In fiction

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    Many science fiction books and films have imagined characters being “trapped in virtual reality”.

    A comprehensive and specific fictional model for virtual reality was published in 1935 in the short story “Pygmalion’s Spectacles”[5] by Stanley G. Weinbaum. A more modern work to use this idea was Daniel F. Galouye’s novel Simulacron-3, which was made into a German teleplay titled Welt am Draht (“World on a Wire”) in 1973. Other science fiction books have promoted the idea of virtual reality as a partial, but not total, substitution for the misery of reality, or have touted it as a method for creating virtual worlds in which one may escape from Earth.

    Stanisław Lem’s 1961 story “I (Profesor Corcoran)”, translated in English as “Further Reminiscences of Ijon Tichy I”,[73] dealt with a scientist who created a number of computer-simulated people living in a virtual world. Lem further explored the implications of what he termed “phantomatics” in his nonfictional 1964 treatise Summa Technologiae. The Piers Anthony novel Killobyte follows the story of a paralyzed cop trapped in a virtual reality game by a hacker, whom he must stop to save a fellow trapped player slowly succumbing to insulin shock.

    A number of other popular fictional works use the concept of virtual reality. These include William Gibson’s 1984 Neuromancer, which defined the concept of cyberspace, and his 1994 Virtual Light, where a presentation viewable in VR-like goggles was the MacGuffin. Other examples are Neal Stephenson’s Snow Crash, in which he made extensive reference to the term avatar to describe one’s representation in a virtual world, and Rudy Rucker’s The Hacker and the Ants, in which programmer Jerzy Rugby uses VR for robot design and testing. The Otherland series of 4 novels by Tad Williams, published from 1996 to 2001 and set in the 2070s, shows a world where the Internet has become accessible via virtual reality.

    The Doctor Who serial “The Deadly Assassin”, first broadcast in 1976, introduced a dream-like computer-generated reality, known as the Matrix. British BBC2 sci-fi series Red Dwarf featured a virtual reality game titled “Better Than Life”, in which the main characters had spent many years connected. Saban’s syndicated superhero television series VR Troopers also made use of the concept.

    The holodeck featured in Star Trek: The Next Generation is one of the best known examples of virtual reality in popular culture, including the ability for users to interactively modify scenarios in real time with a natural language interface. The depiction differs from others in the use of a physical room rather than a neural interface or headset.

    The popular .hack multimedia franchise is based on a virtual reality MMORPG dubbed “The World”. The French animated series Code Lyoko is based on the virtual world of Lyoko and the Internet.

    In 2009, British digital radio station BBC Radio 7 broadcast Planet B, a science-fiction drama set in a virtual world. Planet B was the largest ever commission for an original drama programme.[74]

    The 2012 series Sword Art Online involves the concept of a virtual reality MMORPG of the same name, with the possibility of dying in real life when a player dies in the game. Also, in its 2014 sequel, Sword Art Online II, the idea of bringing a virtual character into the real world via mobile cameras is posed; this concept is used to allow a bedridden individual to attend public school for the first time.

    Featured in 2012, Accel World expands the concept of virtual reality using the game Brain Burst, a game which allows players to gain and receive points to keep accelerating; accelerating is when an individual’s brain perceives the images around them 1000 times faster, heightening their sense of awareness.
    Motion pictures
    World Skin (1997), Maurice Benayoun’s virtual reality interactive installation

    Rainer Werner Fassbinder's 1973 film Welt am Draht, based on Daniel F. Galouye's novel Simulacron-3, shows a virtual reality simulation inside a virtual reality simulation
    In 1983, the Natalie Wood / Christopher Walken film Brainstorm revolved around the production, use, and misuse of a VR device.
    Total Recall, directed by Paul Verhoeven and based on the Philip K. Dick story "We Can Remember It for You Wholesale"
    A VR-like system, used to record and play back dreams, figures centrally in Wim Wenders' 1991 film Until the End of the World.
    The 1992 film The Lawnmower Man tells the tale of a research scientist who uses a VR system to jumpstart the mental and physical development of his mentally handicapped gardener.
    The 1993 film Arcade is centered around a new virtual reality game (from which the film gets its name) that actively traps those who play it inside its world.
    The 1995 film Johnny Mnemonic has the main character Johnny (played by Keanu Reeves) use virtual reality goggles and brain–computer interfaces to access the Internet and extract encrypted information in his own brain.
    The 1995 film Virtuosity has Russell Crowe as a virtual reality serial killer name SID 6.7 (Sadistic, Intelligent and Dangerous) who is used in a simulation to train real-world police officer, but manages to escape into the real world.
    The 1999 film The Thirteenth Floor is an adaptation of Daniel F. Galouye's novel Simulacron-3, and tells about two virtual reality simulations, one in another.
    In 1999, The Matrix and later sequels explored the possibility that our world is actually a vast virtual reality (or more precisely, simulated reality) created by artificially intelligent machines.
    eXistenZ (1999), by David Cronenberg, in which level switches occur so seamlessly and numerously that at the end of the movie it is difficult to tell whether the main characters are back in "reality".
    In the film Avatar, the humans are hooked up to experience what their avatars perform remotely.
    Surrogates (2009) is based on a brain–computer interface that allows people to control realistic humanoid robots, giving them full sensory feedback.
    

    Concerns and challenges

    There are certain health and safety considerations of virtual reality. For example, a number of unwanted symptoms have been caused by prolonged use of virtual reality,[75] and these may have slowed proliferation of the technology. Most virtual reality systems come with consumer warnings.

    In addition, there are social, conceptual, and philosophical considerations with virtual reality. What the phrase “virtual reality” means or refers to, is not always unambiguous. In the book The Metaphysics of Virtual Reality by Michael R. Heim, seven different concepts of virtual reality are identified: simulation, interaction, artificiality, immersion, telepresence, full-body immersion, and network communication.

    There has been an increase in interest in the potential social impact of new technologies, such as virtual reality. In the book Infinite Reality: Avatars, Eternal Life, New Worlds, and the Dawn of the Virtual Revolution, Blascovich and Bailenson review the literature on the psychology and sociology behind life in virtual reality.

    In addition, Mychilo S. Cline, in his book Power, Madness, and Immortality: The Future of Virtual Reality, argues that virtual reality will lead to a number of important changes in human life and activity.[76] He argues that virtual reality will be integrated into daily life and activity, and will be used in various human ways. Another such speculation has been written up on how to reach ultimate happiness via virtual reality.[77] He also argues that techniques will be developed to influence human behavior, interpersonal communication, and cognition.[78] As we spend more and more time in virtual space, there would be a gradual “migration to virtual space”, resulting in important changes in economics, worldview, and culture.[79]

    Philosophical implications of the concept of VR are discussed in books including Philip Zhai’s Get Real: A Philosophical Adventure in Virtual Reality (1998) and Digital Sensations: Space, Identity and Embodiment in Virtual Reality (1999), written by Ken Hillis.

    Virtual reality technology faces a number of challenges, most of which involve motion sickness and technical matters. Users might become disoriented in a purely virtual environment, causing balance issues; computer latency might affect the simulation, providing a less-than-satisfactory end-user experience; the complicated nature of head-mounted displays and input systems such as specialized gloves and boots may require specialized training to operate, and navigating the non-virtual environment (if the user is not confined to a limited area) might prove dangerous without external sensory information.

    In January 2014, Michael Abrash gave a talk on VR at Steam Dev Days.[80] He listed all the requirements necessary to establish presence and concluded that a great VR system will be available in 2015 or soon after. While the visual aspect of VR is close to being solved, he stated that there are other areas of VR that need solutions, such as 3D audio, haptics, body tracking, and input. However, 3D audio effects exist in games and simulate the head-related transfer function of the listener (especially using headphones). Examples include Environmental Audio Extensions (EAX), DirectSound and OpenAL.

    VR audio developer Varun Nair points out that from a design perspective, sound for VR is still very much an open book. Many of the game audio design principles, especially those related to FPS games, crumble in virtual reality. He encourages more sound designers to get involved in virtual reality audio to experiment and push VR audio forward.[81]

    There have been rising concerns that with the advent of virtual reality, some users may experience virtual reality addiction.[82]
    Pioneers and notables
    This section may contain excessive, poor, irrelevant, or self-sourcing examples. Please improve the article by adding more descriptive text and removing less pertinent examples. See Wikipedia’s guide to writing better articles for further suggestions. (February 2015)
    This section is in a list format that may be better presented using prose. You can help by converting this section to prose, if appropriate. Editing help is available. (January 2016)

    Thomas A. Furness III
    Maurice Benayoun
    Mark Bolas
    Fred Brooks
    Anshe Chung
    Edmond Couchot
    James H. Clark
    Doug Church
    Char Davies
    Tom DeFanti
    David Em
    Scott Fisher
    William Gibson
    Morton Heilig
    Eric Howlett
    Myron Krueger
    Knowbotic Research
    Jaron Lanier
    Brenda Laurel
    Palmer Luckey
    Michael Naimark
    Randy Pausch
    Mark Pesce
    Warren Robinett
    Philip Rosedale
    Louis Rosenberg[83][84][85]
    Dan Sandin
    Susumu Tachi
    Ivan Sutherland
    

    Commercial industries
    This section is in a list format that may be better presented using prose. You can help by converting this section to prose, if appropriate. Editing help is available. (February 2015)

    The companies working in the virtual reality sector fall broadly into three categories of involvement: hardware (making headsets and input devices specific to VR), software (producing software for interfacing with the hardware or for delivering content to users) and content creation (producing content, whether interactive or passive, for consumption with VR hardware).

    HMD devices

    Altergaze
    Carl Zeiss (Carl Zeiss Cinemizer)
    Durovis Dive
    Facebook (Oculus Rift)
    Gameface
    Google (Google Cardboard)
    HTC (HTC Vive)
    Microsoft (Microsoft HoloLens)
    Razer (OSVR Hacker Dev Kit)
    Samsung (Samsung Gear VR)
    Sony Computer Entertainment (PS VR)
    Starbreeze Studios (StarVR)
    VRVana (Totem)
    

    See Comparison of retail head-mounted displays

    Input devices

    Cyberith Virtualizer
    Intugine
    Leap Motion
    Nokia (Nokia OZO camera)
    Sixense
    Virtuix Omni
    ZSpace (company)
    VicoVR
    

    Software

    VREAM
    

    Content

    Clone Mediaworks
    Framestore
    iClone
    Innervision
    Moving Picture Company
    Reel FX
    xRes
    

    Emerging technologies

    360 degree video
    Augmented reality
    HoloLens
    Intel RealSense
    Magic Leap
    Mixed reality
    Ultrahaptics
    VRVana
    

    Companies

    Google
    Facebook
    Apple
    HTC
    Valve
    Samsung
    Microsoft
    Intel
    Campustours
    Sketchfab
    

    Artists

    Rebecca Allen
    Maurice Benayoun
    Sheldon Brown
    Char Davies
    David Em
    Myron Krueger
    Jaron Lanier
    Brenda Laurel
    Michael Naimark
    Jeffrey Shaw
    Nicole Stenger
    Tamiko Thiel
    
    展开全文
  • vue 动态给每个页面添加title、关键词和描述

    千次阅读 热门讨论 2020-07-31 11:44:39
    前言:直接写html加title和关键词想必大家都知道怎么去加,但用vue框架开发的项目我们怎么去动态的给每个页面添加呢 ↓ 先在router.js里面配置我们的title、关键词和描述 { path: '/train', ...

    前言:直接写html加title和关键词想必大家都知道怎么去加,但用vue框架开发的项目我们怎么去动态的给每个页面添加呢 ↓

    先在router.js里面配置我们的title、关键词和描述

    	{
    		path: '/train',
    		name: 'Train',
    		component: () => import('../components/page/Train.vue'),
    		meta: {
    			title: '教师培训-恩启官网',
    			content: {
    				keywords: '教师培训、恩启培训、恩启云课堂、特教老师、线上服务、徐紫薇、王学钢',
    				description: '恩启教师培训专注于自闭症行业教师专业技能提升培训,评估师培训。为自闭症康复教师提供科学、系统的在线课程、咨询服务。'
    			}
    		}
    	},
    

    在main.js里用beforeEach(前置守卫)判断

    router.beforeEach((to, from, next) => {
    	if (to.meta.content) {
    		let head = document.getElementsByTagName('head');
    		let meta = document.createElement('meta');
    		document.querySelector('meta[name="keywords"]').setAttribute('content', to.meta.content.keywords)
    		document.querySelector('meta[name="description"]').setAttribute('content', to.meta.content.description)
    		meta.content = to.meta.content;
    		head[0].appendChild(meta)
    	}
    	if (to.meta.title) {
    		document.title = to.meta.title;
    	}
    	next()
    });
    

    这样就行了。

    后续补充:vue的特点呢就是组件系统跟数据驱动,嗯,是特别方便的,比如我们一个组件里根据路由状态值判断初始化加载不同的页面(比如在前一个页面有三个按钮:北京、上海、深圳)点击进去不同的城市页面,但我们的页面都是用的同一个组件,如下路由配置:↓

    	{
    		path: '/cityDetail',
    		name: 'CityDetail',
    		component: () => import('../components/page/CityDetail.vue'),
    		meta: {
    			title: '',
    			content: {
    				keywords: '',
    				description: ''
    			}
    		}
    	},
    

    这里我们再router.js里没进行关键词的填写,因为他有好几个不同城市加载,我们可以在对应的组件里加个判断

    if(orgUrl == 'beijing'){
        document.querySelector('meta[name="keywords"]').setAttribute('content', '北京教研中心,恩启教研中心,IEDA教研中心')
        document.querySelector('meta[name="description"]').setAttribute('content', '恩启诞生于2014年 ,是一家专业的自闭症康复机构。北京教研中心,位于北京市朝阳区孙河地铁站对面弘园五号创意生活园A5,联系方式13021253543,北京教研中心。')
        document.title = '恩启IDEA·北京教研中心-直营连锁-恩启官网';
    }else if(orgUrl == 'shanghai'){
    	 document.querySelector('meta[name="keywords"]').setAttribute('content','上海静安教研中心,恩启教研中心,IEDA教研中心');
         document.querySelector('meta[name="description"]').setAttribute('content', '恩启IDEA静安中心坐落于上海市大宁中心广场,毗邻大宁音乐中心,交通便利,生活便捷。');
         document.title='恩启IDEA·上海静安教研中心-直营连锁-恩启官网';
    }
    

    这样设置就ok了;

    如有错误请大家评论纠正,谢谢~~~~

    展开全文
  • git安装克隆提示 Cloning into ‘项目’… remote: HTTP Basic: Access denied,看到这个问题,我以为这我的帐号没有分配克隆权限呢 解决问题:生成自己帐户私匙,配置到git上面 git安装克隆提示Cloninginto项目 ...

    git安装克隆提示 Cloning into ‘项目’… remote: HTTP Basic: Access denied,看到这个问题,我以为这我的帐号没有分配克隆权限呢
    解决问题:生成自己帐户私匙,配置到git上面
    git安装克隆提示Cloninginto项目
    git clone git@gitee.com:yys926/tp.git
    创建用户
    git config --global user.name “名称”
    git config --global user.email “邮箱”
    git 生成秘钥 并连接 码云
    1, ssh-keygen -t rsa -C “xxxxx@xxxxx.com” 码云的邮箱
    按三次回车,不用添加任何东西
    2, cat ~/.ssh/id_rsa.pub
    查看秘钥 并复制 到 码云上
    3, ssh -T git@gitee.com
    出现 (Welcome to Git@OSC, yourname!) 证明链接成功

    展开全文
  • 管理MediaPlayer的状态

    2014-07-25 19:09:56
    管理状态  对MediaPlayer要记住的另一个方面就是"基于状态".即,MediaPlayer有一个内部的状态,因为特定的操作只能在特定的状态时才有效,所以你必须在写代码时一直注意到它的变化.如果你在错误的状态下执行一...
  • android 加密解密学习

    2017-03-02 11:40:25
    项目中要求: 一 .运动数据加密功能 信息加密说明: 算法名称:DES 加密模式:ECB 填充方式:PKCS7Padding 经base64编码后的公钥:hU0c2Tas2...二维码内容:interface://treadmill.do?data=base64编码后的加密运动数据
  • virtually all occasions except maybe the daily grind about the treadmill. fxoiu2013-06-09xy7akj 来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/28959917/viewspace-763617/,如需...
  • Send [1] times, still failed

    千次阅读 2016-08-06 08:02:00
    com.alibaba.rocketmq.client.exception.MQClientException: Send [1] times, still failed, cost [696094]ms, Topic: TopicTest, BrokersSent: [broker-b, null] See ...
  • Purchaser Experiences isn't going to stop workingugg outlet online its treadmill studies by selling price a...
  • 在使用IntentService时出现了java.lang.RuntimeException: Unable to instantiate service这个异常。为什么会出现这个异常呢。因为我们在使用IntentService时,都会习惯性的用系统给我们实现的方法。...
  • treadmill. But that doesn't seem to stop us from putting them on. cheap red bottom heels leather material second adds a great looking formation so that you can a slouched further up form. Along ...
  • it to be tough to run over a treadmill or do squats in the gym. 'Surely everything needed to be done was to turn back numbers, to not forget the time motor, too. Bowling attire typically involves...
  • daily grind around the treadmill. fxoiu2013-06-09xy7akj 来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/28959684/viewspace-763593/,如需转载,请注明出处,否则将追究法律责任。 ...
  • 心率变异性的功率谱密度分析确定lnHFR-R,径向眼压测定确定AIx @ 75,Bruce Treadmill协议确定VO2max。 结果:在男性中,lnHFR-R与AIx @ 75正相关并显着预测AIx @ 75(P = 0.005),而在女性中则没有(P = 0.49)。...
  • 【数据集】Kinetics-600 dataset介绍

    万次阅读 多人点赞 2018-04-29 18:02:50
    running on treadmill skateboarding surfing crowd using segway waiting in line mobility – water (10) crossing river diving cliff jumping into pool scuba diving snorkeling ...
  • db.Routines.find({"type": "Treadmill Run", "distance": {$eq: "3"}},{_id:0, datetimeRoutine:0, type:0}) We use the equals operator ($eq) to find all the Treadmill Runs where the distance is equal to ...
  • 锻炼和训练师 (Workouts and Trainers) Fitness+ will launch with a range of workouts, including yoga, cycling, dance, treadmill walking and running, strength, core, HIIT, rowing, and mindful cooldown....
  • 近来做行为动作识别,根据近两年的CVPR、ICCV、ECCV论文实验了一序列的动作识别方面的模型,很多都用到了kinetics数据集或者something-something数据集,但是后者的官网目前已经关闭了(可能是因为上月bn20被高通收购...
  • native与html交互小记

    2017-05-25 15:33:42
     <a href="use_treadmill.html">     使用跑步机须知  </a>//# 这种东西有多个,就不多写了    .......     ........     function exitHelp(){  if(exitHelpAndroid)...
  • : "2017-01-10 4:00AM", "type" : "Treadmill Run", "distance" : "3.1", "time" : "30"}) db.Routines.insert({"datetimeRoutine" : "2017-01-13 4:00AM", "type" : "Treadmill Run", "distance" : "3.25", "time" ...

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