Setting Up the PS3Eye
Well, I managed to turn off the auto-exposure on the PS3Eye, with help from Adam Kumpf, the author of the Trackmate software; there's a useful thread relating to inconsistent tracking on the Trackmate discussion forum.
After this, I discovered that the PS3EyeTest application is not the best app to use for setting up the camera - when you change settings (exposure, gain etc) they aren't immediately reflected in the preview window; you have to start and stop capture. Also the app is a tad flaky, so sometimes when you restart capturing you just get a black screen. All of this makes it near impossible to get the settings right.
However, using AMCap (which is also actually bundled with Alex P's Windows driver), you can adjust the settings with a real-time preview, then apply them once you're happy. So that's the way to go in future.
After a bit of tweaking, all the tags on the layout guide sheet are being recognised well. Here's a screen grab from Trackmate:
All those green circles with larger green dots in the middle indicate that the tag info is being picked up across the surface. And here's one with just a few tags placed on the table, which also seems to be working fine:
One small issue, though: the Trackmate software is only reporting a 5fps capture rate, whereas the camera is capable of 60. I will need to find out what's happening here and try to get it running at full speed.
PlayStation 3 Eye Camera
Having read up on some of the example Trackmate projects, it seems that many people are using the PS3 Eye webcam as their preferred camera for this application. I've picked one up from eBay and I can certainly say the quality is a massive step up from the Logitech. This camera will capture 640x480 video at 60 frames per second, which gives a very smooth and impressive image (the old camera got about 15fps - pretty jerky).
Obviously it's a Playstation 3 accessory, so to use it with Windows you need special driver software, which luckily, a clever chap called Alex Popovich has written for us.
I installed the driver, opened the supplied PS3Eye test app, and it worked perfectly. Until I tried to open the Trackmate application, which refused to recognise it and told me I didn't have a webcam installed...
This turned out to be due to the installer not correctly registering the PS3Eye.ax DirectShow Video Source component - I manually registered this using regsvr32, and Trackmate could find the camera with no problems.
I've only had a little time to play with the camera tonight, but I ran into a couple of issues. Although the picture quality is hugely improved and the tracking is much faster, it doesn't seem possible to turn off the automatic exposure, which means that other light sources (like the main light in my room) affect it badly. I couldn't get it to recognise individual tags properly at all, because as soon as I remove the test sheet the exposure dramatically changes and ruins the setup. Hopefully I'll solve this problem with a bit more research.
02/02/2010: Edited the driver link to point to Alex P's new site.
First Tests
The first attempts went well, but I discovered that the Logitech QuickCam E2500 webcam I'm using (see above) is nowhere near well-specified enough to keep up with rapid object movement over the surface. It also seems very difficult to get it in focus and to get the lighting right.
However, surprisingly (despite the fact that the Trackmate tags look like tiny blurry blobs on screen), the tracking is working, and I have managed to successfully control some of the example apps that come with the LusidOSC Processing Library download.
A good first step!
Hardware Build
The first stage was to build a basic enclosure for my table, which I did with a lot of help from my dad and his extensive selection of power tools (thanks, Dad!). I had a custom piece of frosted glass made, which cost about £12, and them we measured and built the wooden enclosure around that.
The inner pieces are pretty basic: just a standard mains bulb holder and a 60w energy saving bulb (I wired two of these in just in case I needed more light), a mains junction box, an inline power switch on the cable, and a Logitech Quickcam E2500 webcam, mounted on a cross member about half way up the sides (see the picture above for details).
Trackmate + LusidOSC Sequencer
This is the video that first got me interested in the Trackmate system: here the table is controlling a basic sequencer application written with Processing.