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karrtoon
Up and Coming
February 24, 2015

New left eye latency issue with UE 4.7 preview 8

I have been messing around with preview 8 today and noticed a brand new issue (which is subtly disorienting). When doing the "tap test" or shaking the hmd while it's on my face it appears the left eye's worldview wobbles quite a bit more than the right eye since this update. This seems to be a new problem since UE4 preview 8? I have tested on the lightroom and first person templates in direct mode. Fresh install of preview 8.

It appears something has changed and it's as if left eye is not getting the same timewarp settings as the right. Let me know if you can confirm this by shaking the hmd quickly (and close each eye), the world stays nearly perfectly still in the right eye only.

Edit: Interesting, after further testing this appears to be happening in Unity demos now too (in both direct and extended mode). The only thing I changed recently was upgrade my Nvidia driver to 347.52 So this subtle issue might extend past UE4 and perhaps nobody has noticed yet. If someone could confirm by using 347.52 and shake hmd quickly and testing each eye would be helpful. Does one eye's view wobble slightly more than the other for you too?

System Specs:
GTX 980
X99-Deluxe MB
Core i7 5820k
Windows 8.1

Edit2: Tested on second PC and same issue. It is barely noticeable but I can see it, I would say less than 5ms difference between left and right eye. (I must sound crazy saying that I can estimate 5ms difference) but it is as if left eye is not fully 0 post present latency but right eye is. Does anyone else have an eye for this stuff (no pun) that could confirm? Shake HMD vertically up and down quickly to test world's wobble and compare both sides while staring at something in the scene.
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    8 replies

    artyom17
    Up and Coming
    February 25, 2015
    I'll try to repro this, however, I am not that sensitive to latency, unfortunately. Which Oculus Runtime version do you use?

    Edit: Just tried the final, official 4.7 (4.7.1) - I really don't see anything wrong with eyes. However, my NVidia driver is 344.65. I'll try to update to the 347.52 and re-do the test.
    karrtoonAuthor
    Up and Coming
    February 25, 2015
    "artyom17" wrote:
    I'll try to repro this, however, I am not that sensitive to latency, unfortunately. Which Oculus Runtime version do you use?

    Edit: Just tried the final, official 4.7 (4.7.1) - I really don't see anything wrong with eyes. However, my NVidia driver is 344.65. I'll try to update to the 347.52 and re-do the test.


    Using 0.4.4 runtime, direct mode. You have to vibrate rift up and down in hand pretty quickly to see the difference, perhaps while staring at a single point/object like a light or a box. Keeping your head perfectly still. Unfortunately I can't capture exactly what I am talking about on video. :( (everything looks in sync on fraps recording)
    karrtoonAuthor
    Up and Coming
    February 25, 2015
    Okay, I tried to record a video through the lense with my phone to show what I am seeing. I tried to shake the hmd the exact same amount each time. If you stare at "start" text you can kind of see what I am talking about. It is slightly higher latency and wobbles a lot more in left side. The first part of video is starting with left lense.

    http://www.mediafire.com/watch/633v3bq1 ... atency.mp4

    It's much more prevelant in person, not the greatest video sorry
    artyom17
    Up and Coming
    February 25, 2015
    Very interesting.... I think I can see that on your video. Let me install those drivers and will see if I can repro it.
    artyom17
    Up and Coming
    February 25, 2015
    Can you check and report here the latency numbers showed by 'hmd stats' console command?
    karrtoonAuthor
    Up and Coming
    February 25, 2015
    Will do, will be back tonight and post results.


    Edit: Okay for Couch Knight it says:

    Timewarp: On
    Vsync: On
    Upd On GT/RT: On / On
    FinFr: On
    FOV V/H: 106.09 /94.16
    w-to-m: 100.00 uu/m
    Latency, ren: 13.86ms tw: 4.86ms pp: 0.83ms

    PostTr: POn
    Vision: ACQ
    IPD: 67.30 mm
    LowPers: On
    Overdrive: On

    I still see the latency in left eye here if I do the test here. Not sure if these numbers coming from right eye only or if this is a normal reading?
    artyom17
    Up and Coming
    February 25, 2015
    Yeah, it is measured in the right eye, actually. It seems like this is a bug in our timing code. Our current dev version of the SDK doesn't seem to have this issue, we've made several fixes in this regard there. I can't tell ETA of the next SDK release, though.
    karrtoonAuthor
    Up and Coming
    February 25, 2015
    Thanks for trying to spot it. Glad to hear it most likely got fixed sometime down the line. Will wait for next SDK :)
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