Hi,

in late 2007 I created a little wrapper for Google's opensource & crossplatform ZXing library, in order to use QR codes in a similar fashion to the fiducial markers used by reacTIVision. Back then ZXing was at a really early development stage and their decoder too unstable & slow for my desired purposes. However, 1.33 years later a revisit of their project shows just how much this has moved on and in good capture conditions, realtime tracking of QR codes is now a reality.

See the short video for a demonstration: http://vimeo.com/3820225

Since a few people have been asking me about the demo recently, here's just a heads up that the source code is now available under GPLv3 as part of my new public code repository at:

http://pspctclr.com/hg

To replicate what's shown in the video you'll need both ZXingTestCamServer and ZXingTestClient projects. Only the ZXingTestCamServer makes use of ZXing though, handles the wrapping and tracking, as well as is broadcasting the found ID & location of a marker to connected clients via TCP...

If you want to create QR codes at different sizes you can use the pre-alpha stage, preliminary web API of my related SpimeCo.de project: http://spimeco.de (or use any other generator, e.g. Kaywa). ZXing itself has a QRcode encoder too, but requires a bit more effort.

If you're interested in developing this use case further, here're 2 key things which should be implemented first:

* add computation of marker orientation/rotation to become more compatible with reacTIVision
* switch to TUIO for broadcasting marker events/details (also consult tuio.org and specifically http://www.tuio.org/?tuio20)
* broadcast a timeout event when no more marker has been recognized for past x milliseconds
* bundle into a proper library (*preferably without requiring a PApplet instance)

Again, ZXing itself is released under ALv2 and my demo & wrapper under GPLv3 (which is compatible with their license). I might not have time in the near future to develop this much further myself, but would love if this is getting picked up, since QR codes provide sooo much more potential... If you're interested, please do let me know so at least we can consult each other about progress. Cheers!

Happy Easter everyone!