View Full Version : HMD view jumps

09-14-2017, 06:05 AM

When I run my current Vizard program (in Vizard 5.7) and view using an HMD (Oculus Rift DK2 running SDK 1.16), the view occasionally jumps to the side and back again. Itís a flicker really, over in a second or less, but itís quite jarring. This seems to happen at random intervals, often a few minutes or sometimes tens of minutes apart, and it happens regardless of whether or not the avatar is moving. It does not happen, as far as I can tell, on the 2D view I have running concurrently on the monitor, or in a separate program I wrote for 3D glasses that doesnít use an HMD. Iíve used Vizconnect to set up all the interactions between HMD, tracker, game controller, avatar and transport, but Vizconnect doesnít seem to be the problem because the jumping also occurs in an older Vizard program that I wrote without using Vizconnect.

To be honest, itís difficult to make comparisons between programs because the intervals at which jumps occur are so variable. It might be that although jumping occurs in all my HMD programs, the frequency differs between them. A case in point is when using the HMD to view the Oculus Ďcityscapeí home site without running a Vizard program: in this case I have seen jumping happen once, but it seems very much less frequent than when running my current Vizard program.

I wonder if the jumping could be a hardware issue. My graphics card (an NVIDIA GTX970) meets the minimum system requirement for the Oculus Rift DK2 and Iím using a non-shared USB 3.0 port for the positional tracker. However, my processor is a bit slower than the minimum system requirement: itís an Intel Xeon E5520 (4 cores, 8 threads, 2.26 GHz), whereas the minimum requirement specifies an Intel Core i5-4590 (4 cores, 4 threads, 3.3 GHz) (https://product-guides.oculus.com/en-us/documentation/dk2/latest/).

Any advice would be much appreciated.


09-14-2017, 09:31 AM
Actually, I was wrong about one thing. When the view jumps on the HMD, it does also jump on the 2D display that shows concurrently on the monitor. The jump is less noticeable on the 2D display, but it is there. I teamed up with somebody else so we could monitor both views at once.

09-14-2017, 09:09 PM
You could try testing with a simple Vizard script like oculusExample.py (File > Quick Open > Type: oculusExample). That should run at a stable 75 fps in the DK2. Press F4 to see the framerate. If the framerate is stable and you still notice jumps it's likely not a rendering issue. It could be due to drivers, hardware, or the tracking.

10-04-2017, 07:17 AM
Hi Jeff,

Thanks for your reply. The frame rate reading fluctuates continuously between about 74 and 76 fps, changing almost too fast to see Ė I think this probably counts as stable, doesnít it? When the HMD image jumps, this has no effect on the frame rate reading.

I donít think the graphics card driver is likely to be the problem, as I updated this quite recently. The Oculus SDK, which includes drivers, is version 1.16 and this was also installed quite recently. I wonder if updating to version 1.18 would make any difference?

As regards the tracker, I have it plugged into a USB 3.0 port on a PCIe USB 3.0 card that is connected to the motherboard. As far as I can tell, this PCIe slot isnít sharing bandwidth with anything else. At any rate, the Oculus Configuration Utility showed that the tracker was not dropping frames when I was running Oculus SDK 0.8 (this utility no longer seems to be available in SDK 1.16).

As far as the PC hardware is concerned, I suppose it could either be the processor or the graphics card, as the processor falls short of the minimum system requirements and the graphics card only just meets them. Do you have a view as to which is the more likely candidate?