原文： https://www.theregister.co.uk/2018/01/16/human_limits_of_vr_and_ar/ 作者：David Matthews, 16 Jan 2018 ----------------------------------------------- A headache to perfect 追求完美困难重重 But getting eye-tracking technology good enough "is really hard, and even the best companies out there are sort of only barely good enough," says Luebke, as tracking can be thrown off by things like contact lenses and mascara. Individual differences in our face and eyes mean that "they are not robust enough across the population". To be commercially viable, they need to work across 99.9 per cent of people, he thinks (earlier this year, SMI said that their technology currently worked for 98 per cent of the population). Luebke表示，然而, 要视觉追踪技术达标十分困难。即使是现在最好的公司也只能做到勉 强及格。包括隐形眼镜或是睫毛膏都可能对干扰视线追踪。脸部及视线移动的个体差异使 得该技术没有能力适用於所有人。Luebke认为，想要可应用于商业上，视线追踪技术要能 应用於99.9%以上的人群。而在今年稍早，SMI表示目前他们的技术可应用於98%的人群。 Why is it so important to get foveated rendering to work? Last year, Michael Abrash, chief scientist at Oculus, warned that making VR sharp enough so that it was "good enough to pass a driver's licence test" required an "order of magnitude" more computing power. 为什麽中心渲染技术如此重要呢？去年，Oculus的首席科学家Abrash提出警示，制造品质 足以通过驾照考试的VR将需要完全不同量级的电脑计算能力。 Even now, with individual pixels still visible when using the very best headsets, VR gaming is around seven times as computationally expensive compared to a PC monitor, Nvidia has calculated. Not only do you need a screen per eye, doubling the number of pixels served, but VR games need to run at at least 90Hz (frames per second). 即使是现有最好的VR头盔在显示上依然有严重的颗粒感。NVIDIA估计，VR游戏的显示成本 大约是萤幕的7倍。一个眼睛一个萤幕代表有两倍的像素需要显示。同时，你还需要高达 90Hz的画面刷新率（每秒帧数）。 译注：就算是高阶游戏，60Hz也大多足够。 Both Abrash and Luebke think foveated rendering is so important to the VR industry that the eye-tracking problem will be solved within five years. According to Abrash, the failure to crack foveated rendering is "the greatest single risk factor" to his predictions of dramatic improvements in VR realism over the next five years. Abrash跟Luebke都认为，视线追踪技术将在5年内解决，届时中心渲染技术在VR产业将更 加重要。Abrash认为， “中心渲染技术突破失败” 是他预测未来5年VR产业突破的的最 大单一不安定因素 VR is also testing the limits of our visual system when it comes to how quickly the screen refreshes. Video games on a monitor are playable at 30Hz, but VR games tend to run at 90Hz and above. Compared to a monitor, VR envelopes far more of our peripheral vision, which, according to Meese, is much more sensitive to flicker than the fovea. VR同时试图以画面刷新率挑战视觉系统的极限。电玩在一般萤幕只需30Hz就足够游玩，但 VR游戏需要90Hz以上。与一般萤幕相比，VR游戏需要更多眼周视觉参与，而相较于眼窝， 眼周对於画面闪烁非常敏感。 The centre of our vision "doesn't care too much about movement," explains Laurence Harris, a professor of psychology, kinesiology, health sciences and biology at York University in Canada. "Motion detection is most important in the periphery, to tell you about your own movement and to detect animals trying to creep up on you." 加拿大约克大学心理学，运动机能学，健康科学与生物学教授Laurence Harris表示：” 人类的视线中心其实对动作变化不太敏感。动作侦测大多由眼周视觉负责。眼周视觉可以 告诉你自身的动作变化，并探查是否有野兽试图攻击你” Nvidia has been experimenting with displays for VR and AR (augmented reality, which layers 3D objects over the real world using transparent visors such as Microsoft's Hololens) that boast frame rates well beyond even 90Hz. Last year, Luebke demonstrated a 1,700 Hz VR display, while another team, also involving company researchers, has demonstrated an even faster AR display, which updates at 16,000Hz. NVIDIA已经成功在VR及AR显示远超过90Hz的画面刷新率。（AR：扩增实境，用透明板将3D 物件覆盖在现实上，例如微软的Hololens）。去年，Luebke成功展示了1700Hz的VR显示。 同时，另一个研究团队已经成功展示更快的画面刷新率，高达16000Hz的AR显示。 Laaaaaaag 画面延迟 The purpose of super-fast refresh rates is to cut down the time between us moving our heads and the display in a VR headset changing to reflect that motion – so-called latency. "Above a certain point you're not going to perceive the flicker even in your peripheral vision... but you can still have the benefit from driving the latency down," Luebke says. 研究更快画面刷新率的目的是为了降低头部移动以及所对应VR显示之间的延迟。Luebke说 ：“刷新速度加快到某个程度，眼周视觉其实已经知觉不到了…但降低延迟依然有助於VR 显示” 。 With so many more frames per second, it becomes possible to add in very slight changes in perspective almost instantaneously when we move our head in VR, driving latency down and making if feel like our bodies in VR are reacting immediately to our real movements, he says. In VR games, the AI and physics might be calculated at no more than 20 frames per second; the rendering then happens at 90Hz; and finally, a super-fast refresh rate allows us to "bolt something on top of that" to make movement feel even more responsive, he says. Luebke表示，随着每秒帧数的增加，显示上有可能增加更多的细节以即时反应头部及VR头 盔的移动，同时降低延迟使得VR使用者获得动作的即时反馈。在VR游戏中，现有AI及物理 引擎可能每秒计算不超过20帧。渲染技术可以使得显示达到90Hz。而超快的画面更新率使 技术更进一步改善动作的反馈。 But in one respect VR still lags far behind our biological limits: we are nowhere near a pixel density that mimics real life. 但从模拟真实世界的角度上来说，现有VR的像素显示密度还远未及人类的生理极限。 In theory, in our fovea, we need about 120 pixels per degree of view to match reality (although Meese says in practice, people generally can't see in finer detail than around 80 pixels per degree). Currently, the best headsets manage about 10 pixels per degree horizontally. Given the need to scale up by a factor of about 10 – on both axes – the increase in resolution required is enormous. "I don't think the technology is there yet for those display pixel densities," says Bryan William Jones, a retinal neuroscientist at the University of Utah. 理论上，人类的眼窝视觉，每一度视角需要大约120像素才符合现实。Meese表示，事实上 大多数人到80像素每度视角以上就没办法看的更细了。目前最好的VR头盔大概可水平显示 10像素每度视角，因此大约在垂直及水平两个向度上都需要再改善十倍的解析度。这个技 术需求十分惊人。犹他大学视觉神经科学家Bryan William Jones表示：” 我不认为现有 的技术可以达到该像素密度” 。 And for VR obsessives who will settle for nothing less than a perfect replica of reality, even 120 pixels per degree might not be enough. Put two lines above each other and move one slightly to the left or right, and it turns out we are "extraordinarily sensitive" to even the tiniest differences between them, says Meese, even to movements smaller than the width of a cone in the eye. 至於对一心追求完美显示现实的VR狂热者来说，每度视角120像素可能还不太够。Meese表 示，想象把两条线重叠，再将任一条线稍微偏左或偏右，即使两条线只有极细微的不同， 哪怕只移动了一点，人类的视觉都能非常敏锐的感觉到。 To match this sensitivity on a computer monitor would require a pixel density that "beggar’s belief", he says, and well beyond 120 pixels per degree. The US Air Force has estimated that a computer screen would require 10,300 pixels per inch to simulate these so called "hyper acuities". This is more than 30 times that of an iPhone 7 (and 12 times the density boasted by a new Samsung VR display, revealed in June, which has a display of around 850 pixels per inch). 为了对应视觉系统对於这种差异的敏感，需要超乎想象的像素密度，远远超过120像素每 度视角。美国空军估计，大约需要在每寸萤幕显示超过10300像素才能满足这种被称为” 超敏”的需求。这大约是iPhone 7 的30倍，是Samsung即将於6月推出的VR显示的12倍。 而三星的新VR显示大约只有每寸850像素。 Such fine-grain vision is rarely used in the real world, says Meese. "The closest example you can think of is threading the eye of a needle, or something like that," he thinks. But it serves as a reminder that imitating the look of real life in VR remains a technological pipe dream – don't expect to do any VR sewing in the next decade or two. ® Meese表示，大多数情况，我们不需要如此高的像素密度。他认为，最接近的例子大概就 是穿针引线，或者类似的事情。但这也提醒我们，用VR模拟真实世界，在现有科技下，依 然是做白日梦。至少在接下来一二十年，用VR缝纫很难成真。 ----------------------------------------------- 想要翻这篇文章的主要原因是， 这篇点出了几个目前技术的瓶颈， 并用量化的方法指出了技术的差距。 由於心理学所谓的恐怖谷效应， 以及实际应用上的必要性， 我不认为未来VR或AR会进化到文中所说的“完全拟真”， 但VR的技术发展，显然还有不短的路要走。 --

※ 发信站: 批踢踢实业坊(ptt.cc), 来自: 68.146.73.68 ※ 文章网址: https://webptt.com/cn.aspx?n=bbs/VR/M.1516663428.A.773.html 提到恐怖谷的原因是是个人的一点猜测。 当VR持续发展，VR显示有一天将有能力显示逼近恐怖谷效应的内容。 到时，消费者对於VR画面改善的反应， 可能不单单只是像现在的高阶显示那般不冷不热，只贩售给特定人群。 而是由於恐怖谷效应，随着VR画面的更加进化， 消费者对於更高阶的画面愈加反感，而销售惨淡。 而缺少了市场的意见及资金反馈， 厂商也将失去动力继续研发更逼真，甚至越过恐怖谷阈值的VR产品。 ※ 编辑: chtguest (68.146.73.68), 01/24/2018 07:10:51