GR1D is an interactive light display with forty low-density pixels. Opening to the general public on April 1st, 2012, GR1D will be situated outside the main entrance to CalArts in an area of the building's unique waffle-pattern ceilings; it will be later be permanently installed in the Machine Lab, Music Technology’s indoor workspace. Each pixel, a three-by-three foot ceiling well, is lighted by a networked 1-watt RGB LED. GR1D will be on public display until commencement on May 18th, 2012.

The display is responsive to interactions with mobile devices (both iOS and Android). Visitors are prompted to scan a QR code which brings them to a local server hosting Netpixl interfaces. GR1D explores the idea of a collaborative environment -- multiple participants can control the display simultaneously and interact with each other. The installation will launch with four modes, three of which are interactive. In the first, users can draw on the interface using their touchscreens. In the second, collaborative frame-based animations can be produced through a round-robin of all active devices. In the third, participants can use their devices accelerometer to 'throw' individual pixels around with simple physics. Lastly, the fourth mode is an ambient info-vis display when no interaction is occurring: colorful patterns based on a sentiment analysis of the day’s tweets related to #calarts and #gr1d.

The installation runs off an Atmel AVR microcontroller with an Ethernet shield. The RGB lights are wired up through a row-based I2C network. Since I2C was only designed for spans of a few meters, each row uses a series of bidirectional line buffers (NXP P82B96-PN) to stay within the i2c limit of 400pF capacitance for each row; in the process, I also designed a breakout PCB for the P82B96 which will be posted later as an Eagle file. To keep costs reasonable, a custom RGB driver PCB was foregone in favor of a commercial one, the BlinkM MaxM.