I’m currently recovering from a very intense, but enjoyable weekend at Hack Day London which Christopher Linden and I attended to help hackers mashup Second Life.

Paul Johnston and Nigel Crawley had brought a webcam, markers and reactivision software they were looking to put to use, so, as we were playing IceTowers with IBM at the time, we thought it might be fun to build a mixed reality version of the IceHouse game Torpedo.

It turns out that Torpedo is particularly well suited to a reactivision implementation as it relies on the position and orientation of pieces placed freely on a playing field, but judging torpedo hits in real life is difficult. It’s also a very simple game, so there was a slim chance that we could build it in 24 hours.

Our plan was to play the game in real life then publish the position and orientation data from reactivision to the web, then use LSL to pull the data in to SL where we could rez the pieces, launch the torpedoes and calculate the results. At the same time a second web cam would stream video of the board in to SL, so that we could watch the game play out in RL then see the results calculated in SL.

Working on the hack was loads of fun and team Supernova did a great job. The software came together amazingly well but it wasn’t until we started running around scavenging tripods, glue guns, gaffer tape and white boards to nail together the hardware side that we started getting lots of interest from the other hackers.

In the end the lightning strikes, storms, leaks and lack of wifi meant that we didn’t complete all of the gameplay, but we managed to demo all of the technical aspects of the hack live in our 90 second presentation.

Everything we used was open source, so anyone will be able to finish off our work or build some other interesting computer vision application in SL. Nigel thought mixed reality spin the bottle would be good fun. Andy Piper has another SLorpedo write up here and a selection of pictures here. Chris took a video of the presentation, so hopefully we’ll be able to make that available soon too.

I’m already back working on the SL infrastructure, but it’s great to be able to hack on interesting SL applications once in a while and hopefully we’ll see some of the hackers at Linden Lab Brighton in the near future.