Obelisk 2

designed and built by Kevin McCormick and Carl Gruesz

Obelisk 2 is an updated and enhanced version of the original Obelisk. The original Obelisk is limited in the variety of persistence-of-vision (POV) images it can display, and the quality of pulse-width-modulation (PWM) patterns it can run. It's difficult to do full-color mixing, due to the way different LED colors are located and how many of them there are.

The first Obelisk had only a single line of LEDs; Obelisk 2 has two lines right next to each other, staggered. LEDs are in groups of four: red, green, blue and yellow, so colors mix easily. Obelisk 2 also has better quality LEDs, far more powerful microcontrollers that drive the LEDs, and a faster data link (it has an Ethernet port and an IP address). There are two segments, each 100 inches long, that can be used separately or stacked on top of each other. A Linux-based GUI controls patterns, and external MIDI or DMX-512 inputs can also be used.

Obelisk 2's primary new feature is a POV mode that displays images in 12 bit color (16 with the yellows). Every pixel in a POV image has 16 possible intensities (4 bits) for red, green and blue; each pixel is individually pulse-width-modulated, giving 4,096 possible colors. This means that any image can be sent to Obelisk 2.

Obelisk 2 was first shown at Burning Man 2001. Like the original Obelisk, it was attached to a radio tower; this time the tower was 50 feet tall.

Circuit boards being assembled

Testing at Warehouse 23: Obelisk 2 in one of its sound-responsive modes

Carl works at the top of the tower

Obelisk 2 displaying a full color POV image at Burning Man. Click here to see the raw bitmap sent to the Obelisk. (photo: Sawyer Fuller)

What it looks like when it's off

On Display

Obelisk 2 has been shown at several parties and events since it returned from Burning Man. As with the Obelisk, the two eight foot segments are usually configured to respond to left and right audio channels.

superCollision at MIT, October 6, 2001 - the eye in the pyramid. (raw bitmap here)

Antidote, November 10, 2001

Radiate, Washington DC Armory, November 24, 2001

Radiate - the Ultraworld logo. (raw bitmap here)

Radiate - an Amanita muscaria mushroom and Saturn (raw bitmaps here and here)

Radiate