Eight Players, Two Xboxes, One Screen
CAIA Technical Report 021224A
December 24th, 2002
Introduction
We recently took a brief diversion from our regular network traffic gathering to try an interesting experiment. Swinburne's Centre for Astrophysics and Supercomputing has a "virtual reality" theatre with a big screen and two polarized projectors. We have two XBoxes and like playing Halo. This report looks at what happened when the two met.
Or more simply: How we got two teams of four players on the same screen at the same time.
The story
In a nutshell:
- We have two Xbox units running Halo, which we typically use with two regular TV screens while gathering multiplayer system-link game traffic.
- Our colleagues have a small theatre with a polarisation-preserving 6 metre (19.6ft) screen (at least 1.5 floors high).
- They also have two independent projectors shining on the screen through polarizing glass filters, one set at +45 degrees and the other at -45 degrees. Typically used in conjunction with matching polarized glasses for 3D imaging and visualization tasks.
- To us the obvious thing was to run one Xbox into each projector, and have the players on each team wear appropriately polarized glasses
The equipment
- Stewart silver screen
- Two Seleco SIM250 home theatre projectors (1024x768 resolution)
- Linear Polarizing filters
- Two Microsoft XBoxes with Halo and eight controllers
- 10Mbit/sec Ethernet hub
Step 1: We fired up the Xboxes. The projectors did their thing, and we created some scenes on the screen that no single Xbox would ever produce. Sadly, before this scene would make any further sense we needed to polarize our sight.
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Projections of two Xboxes, viewed like a normal person
(note the size of the screen relative to the "Exit" door, bottom left of the picture above right)
(note the size of the screen relative to the "Exit" door, bottom left of the picture above right)
Our first reality-check - the glasses. Regular 3D visualization glasses have one +45 degree and one -45 degree lens. This works wonderfully when the polarized projectors are displaying left and right hand views of a 3D scene. We were being different. Each projector displays an entirely different scene, and each team member should only see the output from their Xbox. We needed four pairs of glasses with +45 degree lenses and four pairs with -45 degree lenses. Which we didn't have.
Solution: Take eight pairs of regular 3D glasses, cover with paper the right lens of four and the left lens of the other four. Chant "Ho, ho, ho, and a bottle of rum" and sit around looking like pirates.
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Pirates playing Halo
(yes, there's six here but there were eight in the end....)
(yes, there's six here but there were eight in the end....)
This looks silly, and doesn't actually feel all that comfortable. In addition, some of us needed to keep our 'covered' eye closed anyway since there was enough ambient light floating around to distract it.
Cheating is possible - just tilt your head and you're looking at the other team's screen. Of course, you can no longer see what is happening to you so this tactic can be rather self-limiting. It also isn't too hard to figure out who is cheating.
Step 2: Play. For research purposes, naturally.
The 6 metre screen makes four-player-per-box gaming quite reasonable. (Actually it is quite cool, but we wouldn't want to brag.)
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Without filters, all eight players blend together.
The screen did a good job of preserving the polarization of each image. However, we did need to keep our heads perfectly straight to avoid distracting bleed-through from the 'other image'. We rotated a filter in front of our camera to capture this bleed-through effect.
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Click here for the animated GIF (5 slides, 500KB) as the filter is rotated through 90 degrees
(the blurring is due to shaky hand-held camera technique)
(the blurring is due to shaky hand-held camera technique)
One thing we didn't solve was the sound. One Xbox was connected to a set of speakers, but this provided only one team's audio version of events. A better solution would be to provide headphones for everyone, and feed each team's headphones from their respective Xboxes. Or figure out how to polarize the sound. Or use focused beams, and make each team sit in a huddle together.
Headphones would be easier.
Conclusion
It worked. It was fun having both teams in the same room. We plan to use this technique for some large Halo matches over the Internet (using Xbconnect). We need to build a dedicated set of glasses - four with +45 and four with -45 degree polarization - to make the games truly enjoyable and minimise eye-strain. We probably should also build a wiring harness so that up to four headphones can be attached to each Xbox. The projectors were just bright enough for game play in a darkened theatre, but the dark areas in some maps were difficult to see. Brighter projectors would be nice. (So would lots of money.)
Acknowledgments
- Mark Pozzobon - setting up all the Xbox gear, network cables, taking photos and working with Paul Bourke to make this event happen.
- Paul Bourke - letting us try silly things in his VR Theatre and loaning us suitable polarizing filters.
- Ian Leeder, Adis Fazlic, Paul van den Bergen, David Prior, and Tony Cricenti - volunteering to be pirates for a day.
- Sebastian Zander - taking photos and being a pirate for a day