The “laser” is an LCD Projector (thanks Don!) pointed at the audience. I wrote a program in Processing using the Minim library for beat detection. By applying filters to the input audio, you can extract the beat in real time and use that to control a number of variables, such as timers, colours, sizes, rotations, etc. This however proved unsatisfactory. The “show” it produced looked random and uninspired. I then recorded the output to video, made loops out of the animations, and then used a video editor to try to figure out what looks good and why. I ended up treating the video loops like breakbeat drum loops, chopping and slicing them up, laying them over each other, and keeping everything tight by quantizing to the audio channel. I also used some video effects to create transitions. This was eventually presented as the “laser show”, and now I’ll go back to Processing and see if this type of manipulation can be automated.
In order for this to work, the room has to be filled with smoke. A projector is much to bright to look at, even if projecting nothing but black. The smoke takes the glare off the projector, and gives the beams some volume. Smoke is generated by a small “Halloween” smoke machine (thanks Agnes!)

I also built a chipKit powered “dowser” to flip a flag over the lens with a servo whenever nothing was being shown, but this was unnecessary in practice. Eventually this as to tie into the VGA cable, and whenever the RGB lines went low the flag would flip down covering the lens. There’s provisions for two dowser flags, and one VGA control line, so that two projectors can be used for the show, but only one will project at at a time.

There was going to be another projector used for this show, in sync with the main projector using VLC’s network-sync feature. However Kwartzlab’s wifi was saturated and I wasn’t able to get a stable connection. Next time I will use a wired network. In hindsight I think this would have detracted from the show, so no loss by not having it.

  Thanks Karl for the pictures!