Calibrating the Projectors

Timeframe: Nov 10 - Nov 13, 2008

This week I haven't been doing much of my own software development, but instead I have been helping Kevin re-calibrate the Virtual Immersion room so he can continue working on his pet project.

The Virtual Immersion room is a room in the basement with a huge cylindrical screen (maybe 9' tall by 30' wide). There are three expensive projectors which project onto this wall. To make the projectors line up correctly they need to be calibrated to have a correct cylindrical projection, which was our job.

Basically there is a special graphic that you need to use. The graphic, when viewed on a normal computer monitor, looks like a set of curved horizontal lines. Using the controls on the projectors we project the graphic onto the cylindrical screen and try to make the curved lines parallel to each other. Unfortunately this took us a long time to do. The first screen was what we worked on before going for pizza that one day (like 6-8 hours of work), but each screen got progressively easier. I think we did the last one in 30 minutes, not counting the hour we took to make sure all the projectors matched at the edges perfectly.

Now that the projectors are all set up, Kevin can run his game (he wrote it). The game itself isn't all that cool, it's just a ride in a mining cart down a track in a tunnel. I like to think of it more as a tech demo. He has it setup to

• Correctly warp the graphics for use on multiple screen types
  
• Synchronize multiple computers into running the game at the same time
• Stereoscopic visuals (calibrated to polarized glasses)
  
• Head tracking
• Dolby 5.1 sound with doppler effects

all in real time with the real time graphics. He wrote 95% of the code himself, recently having set up an Subversion server so that his friends can help and contribute code. All in all, it's a really nice demo. He's planning to add physics and other game elements later. The problem may be that he's finished here at INRIA in a few weeks (end of November), so I don't think he'll get to play with the Virtual Immersion room for much longer.