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 On low persistence and 75Hz or less... 
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Golden Eyed Wiseman! (or woman!)

Joined: Fri Jun 08, 2012 8:18 pm
Posts: 1329
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I unfortunately don't have a DK2, so I don't have any first hand experience with what low persistence at typical refresh rates is like, but 75Hz or less on a CRT used to drive me nuts. I know the goal is to increase the refresh rate on future units, and if it's to reduce flicker, I understand why - but I was wondering if it's actually necessary.. If low-persistence is constantly engaged, then I would assume the answer is yes (at least for comfort reasons), but what happens if it's dynamically dis/engaged? For example, in the DK1 if you don't move your head around, you don't notice the judder no matter how much you move/turn your avatar using the mouse/gamepad, and that's with a pretty crappy pixel switching time and full-persistence. AFAIK, low-persistence was devised to only eliminate the judder while physically moving your head, so why not engage low-persistence only beyond some threshold head movement, and then revert back to full-persistence? I don't know how startling or noticeable the transition would be, but there's a huge benefit if it's negligible, or at least tolerable, because then software developers can target 60-75Hz refresh rates which is much more plausible than 90+ without having to significantly reduce image quality or have some monster gaming rig (which is compounded by going beyond 1080p for the consumer version). Any thoughts?

Sat Sep 06, 2014 7:29 pm
3D Angel Eyes (Moderator)
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Joined: Sat Apr 12, 2008 8:18 pm
Posts: 11394
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I believe toggling low persistence dynamically is possible. The issue is that it is not a seamless transition. So it would not be a good experience to switch it on and off all the time.

In any case, it is almost impossible for your head to not be moving at all. Even just the subtle movements from breathing and enough to move a pixel (in which case you end up with blur without using low persistence).

So I don't think it will work. Probably much easier and more reliable just to upgrade to a better graphics card.

check my blog -

Sat Sep 06, 2014 10:00 pm
Golden Eyed Wiseman! (or woman!)

Joined: Fri Jun 08, 2012 8:18 pm
Posts: 1329
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Maybe it's just me, but I didn't find judder to be an issue with small or slow head movements, so it could still stay at full-persistence in those cases. Again, I have no experience with the DK2, so I don't know what it's like at 60-75Hz, but I think it's at least worth looking into to know for sure, as it can offer a substantial benefit. It would be a shame to have to turn down the resolution on a 4k or higher HMD because you don't have a $500+ GPU. You know how difficult it is to run a modern title in stereo at a high res ~100FPS. At least mention the idea to your coworkers.

Sat Sep 06, 2014 11:16 pm
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