We’re always looking down at our phones, anyway. Why not use a huge screen we can share?

The “Digital Abax” puts Kitchener City Hall Rotunda visitors “into the map”…or the picture, or the game board, or any interactive imagery.

Abax is an ancient Greek word for a sand table, or a table with grooves to hold counting objects1. It was used for accounting, for planning (like military campaigns), or for play. Where “abacus” is the mobile device we’re all more familiar with, “abax” is the larger desktop.

The hardware and software of the digital abax turns a vast, otherwise ignored floorspace into a life-sized sand table of light.


Schematic diagram of Abax

The Kitchener City Hall rotunda is a lofty, circular commons space used for many public functions. A staircase and partial balcony expands audience space, but only looking downward.

Three Christie Digital projectors are positioned at 120° intervals, at high angle to maximize coverage. They project similar, not identical, interleaved images, to mask the human figures out of the projection or help eliminate most shadows.

A motion sensor above watches for participants and gestures. The floor is covered with a durable, reflective surface to make the images pop.

The interactive graphics are driven by a powerful embedded computer with multiple graphics subsystems. Web apps create 2D and 3D images from the multiple viewpoints, and respond to gesture input or data from participants’ mobile devices.

This design allows the largest possible audience to interact with the largest possible image, projected on the floor.

Use Cases

Day-glow digital projection shows maps, gameboards, labrynths, and kaleidoscopes, on demand, one after the other.

  • In-the-round theatre or dance.

    The three projectors “clothe” the performers in live video. The motion sensor tracks the motions of the performers, and the animation follows suit. Some of the image will “spill” beyond the form of the performer, as a snowflake-shaped pattern on the floor around them.

  • Participation in public meetings.

    Meeting attendees can “get in the map”, walking amidst the display of data. They can gesture to pick up, carry, and drop elements across the workspace.

  • Immersive art experiences.

    Much larger than existing downward-projected visual attractions, the floorspace becomes a responsive canvas for motion graphics. Passersby can turn a kaliedoscope the size of a rose window pattern.

1 Apparently, there is some controversy over whether abax is a real or separate development, or historical term, from abacus.