[技術] 改善VR可能使得你的電腦無法負荷(下）

看板VR作者chtguest (賤兔)時間6年前 (2018/01/23 07:23)推噓5(5推 0噓 19→)

留言24則, 5人參與討論串1/1

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 追求完美困難重重 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, 要視覺追蹤技術達標十分困難。即使是現在最好的公司也只能做到勉強及格。包括隱形眼鏡或是睫毛膏都可能對干擾視線追蹤。臉部及視線移動的個體差異使得該技術沒有能力適用於所有人。Luebke認為，想要可應用于商業上，視線追蹤技術要能應用於99.9%以上的人群。而在今年稍早，SMI表示目前他們的技術可應用於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. 為什麼中心渲染技術如此重要呢？去年，Oculus的首席科學家Abrash提出警示，製造品質足以通過駕照考試的VR將需要完全不同量級的電腦計算能力。 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). 即使是現有最好的VR頭盔在顯示上依然有嚴重的顆粒感。NVIDIA估計，VR遊戲的顯示成本大約是螢幕的7倍。一個眼睛一個螢幕代表有兩倍的像素需要顯示。同時，你還需要高達 90Hz的畫面刷新率（每秒幀數）。譯註：就算是高階遊戲，60Hz也大多足夠。 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都認為，視線追蹤技術將在5年內解決，屆時中心渲染技術在VR產業將更加重要。Abrash認為， “中心渲染技術突破失敗” 是他預測未來5年VR產業突破的的最大單一不安定因素 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同時試圖以畫面刷新率挑戰視覺系統的極限。電玩在一般螢幕只需30Hz就足夠遊玩，但 VR遊戲需要90Hz以上。與一般螢幕相比，VR遊戲需要更多眼周視覺參與，而相較于眼窩，眼周對於畫面閃爍非常敏感。 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." 加拿大約克大學心理學，運動機能學，健康科學與生物學教授Laurence Harris表示：” 人類的視線中心其實對動作變化不太敏感。動作偵測大多由眼周視覺負責。眼周視覺可以告訴你自身的動作變化，并探查是否有野獸試圖攻擊你” 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已經成功在VR及AR顯示遠超過90Hz的畫面刷新率。（AR：擴增實境，用透明板將3D 物件覆蓋在現實上，例如微軟的Hololens）。去年，Luebke成功展示了1700Hz的VR顯示。同時，另一個研究團隊已經成功展示更快的畫面刷新率，高達16000Hz的AR顯示。 Laaaaaaag 畫面延遲 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. 研究更快畫面刷新率的目的是為了降低頭部移動以及所對應VR顯示之間的延遲。Luebke說：“刷新速度加快到某個程度，眼周視覺其實已經知覺不到了…但降低延遲依然有助於VR 顯示” 。 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，隨著每秒幀數的增加，顯示上有可能增加更多的細節以即時反應頭部及VR頭盔的移動，同時降低延遲使得VR使用者獲得動作的即時反饋。在VR遊戲中，現有AI及物理引擎可能每秒計算不超過20幀。渲染技術可以使得顯示達到90Hz。而超快的畫面更新率使技術更進一步改善動作的反饋。 But in one respect VR still lags far behind our biological limits: we are nowhere near a pixel density that mimics real life. 但從模擬真實世界的角度上來說，現有VR的像素顯示密度還遠未及人類的生理極限。 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. 理論上，人類的眼窩視覺，每一度視角需要大約120像素才符合現實。Meese表示，事實上大多數人到80像素每度視角以上就沒辦法看的更細了。目前最好的VR頭盔大概可水平顯示 10像素每度視角，因此大約在垂直及水平兩個向度上都需要再改善十倍的解析度。這個技術需求十分驚人。猶他大學視覺神經科學家Bryan William Jones表示：” 我不認為現有的技術可以達到該像素密度” 。 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. 至於對一心追求完美顯示現實的VR狂熱者來說，每度視角120像素可能還不太夠。Meese表示，想象把兩條線重疊，再將任一條線稍微偏左或偏右，即使兩條線只有極細微的不同，哪怕只移動了一點，人類的視覺都能非常敏銳的感覺到。 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). 為了對應視覺系統對於這種差異的敏感，需要超乎想象的像素密度，遠遠超過120像素每度視角。美國空軍估計，大約需要在每寸螢幕顯示超過10300像素才能滿足這種被稱為” 超敏”的需求。這大約是iPhone 7 的30倍，是Samsung即將於6月推出的VR顯示的12倍。而三星的新VR顯示大約只有每吋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，大多數情況，我們不需要如此高的像素密度。他認為，最接近的例子大概就是穿針引線，或者類似的事情。但這也提醒我們，用VR模擬真實世界，在現有科技下，依然是做白日夢。至少在接下來一二十年，用VR縫紉很難成真。 ----------------------------------------------- 想要翻這篇文章的主要原因是，這篇點出了幾個目前技術的瓶頸，並用量化的方法指出了技術的差距。由於心理學所謂的恐怖谷效應，以及實際應用上的必要性，我不認為未來VR或AR會進化到文中所說的“完全擬真”，但VR的技術發展，顯然還有不短的路要走。 -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 68.146.73.68 ※ 文章網址: https://www.ptt.cc/bbs/VR/M.1516663428.A.773.html

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提到恐怖谷的原因是是個人的一點猜測。當VR持續發展，VR顯示有一天將有能力顯示逼近恐怖谷效應的內容。到時，消費者對於VR畫面改善的反應，可能不單單只是像現在的高階顯示那般不冷不熱，只販售給特定人群。而是由於恐怖谷效應，隨著VR畫面的更加進化，消費者對於更高階的畫面愈加反感，而銷售慘淡。而缺少了市場的意見及資金反饋，廠商也將失去動力繼續研發更逼真，甚至越過恐怖谷閾值的VR產品。

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