from geometry to pixels

Experiences with Oculus Rift demos

Last week I was at the gamescom in cologne and with some coworkers we managed to give more than 800 demos of our projects and some student projects inside of the Rift. Here I want to share some experiences we gathered.

As we already had given some demos to other coworkers, students as well as publicly we didn’t come totally unprepared. All demos were given on the same machine, this one station was in use for over 10 hours straight during most days (gamescom closes earlier on wednesday/sunday). We had a backup for everything but luckily didn’t need it. For various reasons the Rift was the only screen to be attached to the PC: VSync often only works for one display without a way to select in software to which screen the image refresh should be synced. Youth protection rules at the gamescom prevent us from showing some of the demos on a public screen anyway and as it turned out, some visitors didn’t even want to get spoilered with a description of what they can expect…

Having to control the PC and the demo selection from the Rift itself meant that we needed a demo launcher that rendered 3D for the Rift. This launcher consisted of a skybox and some flying quads with a teaser image of the demo. The user can then select the demo he or she wants to see with the buttons of the gamepad (the quads rotate and the selected image is the one in front of the player). Some of the demos were “locked” until a demonstrator entered the password on the keyboard to unlock them for visitors over 18 years.

Demo launcher for an Oculus Rift

The demo launcher.

The launcher then starts the demo in the background and closes itself so only one application is using the Rifts tracking at any time (and only one OpenGL application is occupying the GPU at any time). This was done by launching shell scripts in the background (we were running Linux). One note on the window manager we picked: Our first choice was KDE but the compositing added noticeable latency even in fullscreen so we switched to a minimalistic Fluxbox without any compositing. All demos were tweaked to run at solid 60 FPS except for one scientific visualisation that dropped to 30 FPS in some extreme cases.

All demos had a time-limit after which the applications terminated automatically. Depending on the demo the limit was reached between roughly 2:40 and 3:30 minutes. Restarting the demos for each person eliminated problems with (yaw)-drift and demos being stuck in unexpected states.

Most visitors used the A cup lenses, very near-sighted ones got the C lenses. We didn’t use the B lenses at all to reduce the amount of lens swaps to speed up the user switching times. In some rare cases the users left there glasses on – but we warned them to be careful not to scratch there glasses. The inter-pupillary distance (IPD) was set to an average of 64mm and not measured (which would have doubled the demo time if you add the needed explanations). Of course the lenses were cleaned between users with a cloth.

The RWTH Aachen booth at the gamescom.

The RWTH Aachen booth at the gamescom on an average afternoon.

From over 800 users, only one had to stop the demo in the middle as he got too sick. Three more felt motion sick afterwards but liked the experience anyway. Two or three more (I’m not sure anymore) had to sit down afterwards for a minute before they could walk in a straight line again. The remaining majority had no problems – but keep in mind that our demos were quite short! Apart from the guy who had to stop in the middle, everyone liked the experience – some even did get in line multiple times. Our average waiting time was around 30 minutes by the way.

While the demos were running you could distinguish three kinds of people:

  • Some were not moving at all – they were totally sitting still even tho we told them before the demo that they could look in any direction (as some demos used sound and the hall way very loud we couldn’t always tell them to look around during the demo).
  • Some (the majority) started sitting still but then quickly began to look around a bit. But like driving a car they mostly looked ahead.
  • A few looked in all possible directions (even behind them) and sometimes even moved there arms and hands – this sometimes looked a bit like a cat chasing a laser-pointer…

Independent of how much the people looked around, some of them had to hold tight to the chair inside of our roller-coaster.

Honestly I didn’t expect so many people to be willing to wait so long in line to try out a demo they didn’t know much about – we showed no videos or even screenshots of the games outside of the Rift.

, ,

Leave a Reply

Your email address will not be published. Required fields are marked *