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The really hard parts.

There are three really hard problems that if solved would make VR far more convincing:

  • Tracking
  • Latency
  • And stimulating the human perceptual system to produce results indistinguishable from the real world

All three are different aspects of the core problem, which is the interaction between the display and the human perceptual system

You may well wonder whether head mounted displays are really so different from monitors.

The answer is yes – and more so than you’d imagine, for two key reasons.

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The first reason is that, as I mentioned earlier, in order for virtual images to seem real, they have to appear to remain in the correct position relative to the real world at all times. That means, for example, that as the head turns in this slide, the virtual view has to change correspondingly to show the correct image for the new head position, just as would happen with a real-world view.

This is obviously required in AR, where virtual images coexist with the real world, but it’s required in VR as well, even though you can’t see the real world, because you have a good sense of your orientation, position, and movements even without the help of vision, thanks to hardware and software in your head that’s effectively a gyroscope, accelerometer, and sensor fusion filter.

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The second reason is that, unlike monitors, VR displays move rapidly relative to both the real world and the eyes.

In particular, they move with your head.

Your head can move very fast – ten times as fast as your eyes can pursue moving objects in the real world when your head isn’t moving.

Your eyes can accurately counter-rotate just as fast.

That means that if you fixate on something while you turn your head, your eyes remain fixed with respect to the real world, but move very quickly relative to the display – and they can see clearly the whole time.

It’s important to understand this, because it produces a set of artifacts that are unique to head mounted displays.

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Ben is the world's most senior professional analyst solely dedicated to the XR industry, having founded Road to VR in 2011—a year before the Oculus Kickstarter sparked a resurgence that led to the modern XR landscape. He has authored more than 3,000 articles chronicling the evolution of the XR industry over more than a decade. With that unique perspective, Ben has been consistently recognized as one of the most influential voices in XR, giving keynotes and joining panel and podcast discussions at key industry events. He is a self-described "journalist and analyst, not evangelist."
  • WormSlayer

    My brain hurts! Still I’m excited that guys like him are excited :D

  • Patrick Hogenboom

    Thanks a bundle for transcribing the whole thing :)

  • shole

    If you want to view the two videos in the presentation and don’t have ms powerpoint, you can rename the .pptx file to .zip and the files are in there as .wmv under \ppt\media\

    • Michael Abrash


      Thank you very much for posting this!


  • Andrés

    Thanks so much for transcribing this!

  • Andreas Aronsson

    I thought I would not get to read/hear the actual talk in some time :D Very interesting, somewhat alarming, but at the end uplifting and inspiring! Thanks for this! Also, you could if you wanted to rename the .pptx to .zip and extract the videos (media folder) and upload them unlisted to Youtube and embed them on this page :) Just a thought!

  • Andreas Aronsson

    Ah, in the time it took me to read this (left the article half-read over night) shole already pointed this out :x oops.

  • Esse

    “That means that if you fixate on something while you turn your head, your eyes remain fixed with respect to the real world, but move very quickly relative to the display”

    Hum, no. If your eyes are fixed (in the head referential), they are fixed in the display referential. Because the display & the head are fixed one to the other.

    This is over complicating the subject. Only matters the head movement. Not the eyes movements.

    • Ben

      I think that, in this context, “fixate on something” means a visual fixation on an object in the external world rather than having the eyes be “fixed” relative to the head. If the head is turning while you fixate an external object, the eyes must counter-rotate in order to maintain a stable fixation (eg: via the VOR). Since the VR display is attached to your head frame, this means that your eyes are rotating relative to the display, and that’s the source of the large relative motion that causes issues.

      • Michael Abrash


        You’re correct – that’s what I meant. If you look at a key on the keyboard and keep doing that while you turn your head, you can easily get your eyes moving at several hundred degrees per second relative to the display.


  • Esse

    “The human perceptual system has evolved to be very effective at detecting such anomalies, because anomalies might be thinking about eating you, or might be tasty.”

    It is not some specific “anomalies detection system”, rather that the human brain has in-depth “routines” to analyse the space & movement, and when you broke the rules the routines fail.

    Like when you are sick in a car.

    So I guess the reaction will not be fear or drooling, more puking.

  • Ben Humberston

    Thanks for the transcript for those of us who couldn’t be there!

  • Mattso

    Yeah, just echoing the sentiments above that having it all transcribed meant I actually got to digest it really quickly. Many thanks!

    Very informative stuff – and here was me thinking it was gonna be easy. :)