Search Unity

Recovering from lost tracking on HoloLens

Discussion in 'VR' started by mwitkamp, Dec 19, 2017.

  1. mwitkamp

    mwitkamp

    Joined:
    Nov 27, 2017
    Posts:
    3
    Whenever I lose tracking on my HoloLens project, I get the "Trying to map your surroundings..." image.

    According to https://developer.microsoft.com/en-us/windows/mixed-reality/tracking_loss_in_unity
    "When the device cannot locate itself in the world, the app experiences "tracking loss". By default, Unity will pause the update loop and display a splash image to the user. When tracking is regained, the splash image goes away and the update loop continues."​

    The problem is that my app just stays paused and never recovers. Is there something else I need to do to regain tracking?
     
  2. JasonCostanza

    JasonCostanza

    Unity Technologies

    Joined:
    May 23, 2017
    Posts:
    404
    What version of Unity are you building in? There should not be anything you need to do other than restore tracking. The tracking lost image is going away just the app won't unpause, correct?
     
  3. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
    I also noticed this today both in 2017.2.0p4 and 2017.3. The tracking image never disappears.
    Note that the image that is shown is completely static. Normally there is some animation in the image to indicate activity.
     
  4. JasonCostanza

    JasonCostanza

    Unity Technologies

    Joined:
    May 23, 2017
    Posts:
    404
    I did some more digging. We are actually already tracking this bug, our developers are working on a fix. I don't have an estimate as to when it will land though, unfortunately. But I can assure you it is on our radar!
     
  5. mwitkamp

    mwitkamp

    Joined:
    Nov 27, 2017
    Posts:
    3
    Just for the record, I'm running 2017.2.1f1 with the latest MR Toolkit.

    Thanks for digging into the issue. Good to know a fix is in the works.

    ~Matt.
     
  6. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
    @JasonConstanza So is this part of a bigger problem with HoloLens tracking? Can you provide a link to the corresponding issue? I am also experiencing tracking instability and extreme color separation when panning my head. Both on 2017.3 and 2017.2.1f1. Tried 2017.1.2 and that does not have this problem.
     
  7. JasonCostanza

    JasonCostanza

    Unity Technologies

    Joined:
    May 23, 2017
    Posts:
    404
    Hi rsmeenk, the issue tracker for that is not public facing, unfortunately.

    Is your quality settings set to Fastest? If not, that can cause some color separation if the frame rate isn't holding a solid rate. I was sent a test project by another user the other day who reported this same behavior but their quality settings were set rather high and reducing it made a good bit of improvement in the color separation.
     
  8. JeffGull

    JeffGull

    Joined:
    Nov 20, 2017
    Posts:
    9
    I had the same problem with color separation, but my frame rate was fine. My problem was the stability plane was set to use the gazed upon target. That didn't work in my project because of the large number of small objects I had. Instead, I set it fixed to 1.65 meters which you normally wouldn't do. But I had a odd case. If your frame rate is good, check the stability plane next.
     
  9. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
    Jason, quality is indeed at fastest and my framerate is always solid 60 fps. I am convinced that this is a bug in Unity perhaps related to the stabilization plane.

    I tested with a few more Unity versions:
    OK: 2017.1.1f1, 2017.1.2p4
    Problem: 2017.2.0p4, 2017.2.1f1, 2017.3

    To check if it was not related to a particular place in my room I tested with the default Holograms app. That did not have an issue and the hologram was stable.

    In my app I placed a hologram at the same location by using the MRTK HandDraggable script. I even forced the stabilization plane modifier script to use the model transform.

    When I walk around it tracking is worse than expected, but then at a certain spot the hologram slides away and returns. It seems as if I am walking through the stabilization plane or something, because the holograms returns to it's location when panning further. If I move my head from left to right across that particular spot I can trigger it again. Because of the rapid movement of the model it is experienced in HL as extreme color separation, but I recorded a video of it and that showed that model quickly slides away and then comes back.
     
  10. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
    Narrowed it down a little; 2017.2.0f3 is fine, but 2017.2.0p1 has the stabilization plane problem.
     
  11. Unity_Wesley

    Unity_Wesley

    Unity Technologies

    Joined:
    Sep 17, 2015
    Posts:
    558
    Can you file a bug please with a min repro project please?
     
  12. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
  13. rsmeenk

    rsmeenk

    Joined:
    Oct 24, 2015
    Posts:
    23
  14. BillDozer

    BillDozer

    Joined:
    Feb 2, 2017
    Posts:
    3
    I want to vote this up, but they marked the link above as a duplicate and I can't a link to the active issue.
     
  15. jghospital

    jghospital

    Joined:
    Nov 22, 2017
    Posts:
    17
    You can now vote for the issue, although it's already been aproved and will be fixed in future updates, dont know yet in which one.