A Three-Dimensional Zoetrope
Stewart Dickson
110 N Whipple St
Fort Bragg, CA 95437

This is the document of the construction of the first prototype Zoetrope, constructed from CAD models of a mathematical metamorphosis.

The first Prototype began with a set of 60 phases of the Costa-Torus metamorphosis, computed in Mathematica, custom software by Stewart Dickson and Alias|Wavefront Maya.

The metamorphic pieces were unioned with a standardized base. 3-D, Extruded numerals were applied to the base of each unique piece. The phases ran from 0 to 30 and back to 0 to form a two-second animation loop at 30 fps.

Computer-Generated Sculpture Computer-Generated Sculpture

This is a 3-D print of the frame 30 piece, rendered on the Stratasys Genisys Fused Deposition Modeler at the 1999 SIGGRAPH STUDIO. Note the 1/8" dia. mounting holes, at 1/2" centers -- suitable for 4-40 machine screws.

Two sets of the pieces, 0 to 30 were constructed at the PRISM Center West, Institute for Studies in the Arts, Arizona State University, in 9 days preceding and during a Telesculpture Colloquium from October 1-9, 1999. The machine on which the pieces were constructed was a Stratasys Genesis Fused Deposition Modeling machine.

Stratasys Genisys at Work Stratasys Genisys at Work

Meanhwile, First Prize was awarded to this project, on the basis of the computer-rendered proposal, at the First Digital Sculpture Competition at the French Senate in Paris, October 8-9, 1999.

The physical installation of the Zoetrope began with a 22-inch steel bicycle rear wheel, purchased surplus from Arizona State University Physical Plant, and a portion of the frame of the bicycle from which the wheel came. The frame portion was brazed to a steel plate, drilled with mounting holes. 120 pairs of 1/8" mounting holes, at 1/2" centers were drilled in the rim of the wheel.

Zoetrope Cabinet Disassembled

A base for the Zoetrope cabinet was constructed from 11/32" G1S plywood. The dimensions of the base were 27-3/4" X 8-3/4" X 8". The steel wheel frame was mounted to the cabinet base.

Zoetrope Cabinet Unfinished

The cabinet proper was constructed from 11/32" G1S plywood, with viewing windows designed in.

Viewing Window Detail

This is a detail view of a cabinet viewing window during construction.

A Robbe Power 400/35 DC electric model airplane motor was chosen to turn the wheel. The motor is rated at from 4.8 to 8 volts, 4.5 Amps, 17,000 RPM. The motor was equipped with a 3.7:1 orbital reduction gearhead, which reduced the rotation to roughly 6,000 RPM.

Interior Mechanical Detail

A 1/2" diameter brass-and-rubber VCR capstan roller was mounted on the motor shaft. The motor/roller is held against the rim of the wheel via a spring-loaded rotational mount. The motor is driven by a 5-volt power supply. A 4-ohm rheostat is in series with the motor to reduce the rotation by about half. The resulting speed of the wheel is 30RPM.

Interior Mechanical Detail

An Infrared LED and phototransistor pair are located on opposite sides of the wheel rim, such that the base of each metamorphic piece will interrupt the beam as it passes. This produces a TTL signal from the phototransistor as the wheel rotates.

Interior Mechanical Detail

A set of red, green and blue super-bright LEDs are mounted at each viewing window. The LEDs are driven by a octal bufer/driver circuit, capable of a total fan-out of around 120 TTL input loads.

Because the duty-cycle of the phototransistor pulse is approximately 25% -- there is considerable smearing of the image of a metamorphic piece as it passes the phototransistor. A 555 timer circuit is used to shorten the pulse considerably, to sharpen the image of the Zoetrope.

Press here for the diagram of the Zoetrope wiring and timing circuit.

Interior Electrical Detail

The timing circuit board is mounted inside the Zoetrope cabinet and runs off the same power supply as the motor.

The Zoetrope cabinet mounts onto a pedestal base, so that the installation is a free-standing unit. The 18-amp 5VDC power supply (surplus) used in the first prototype is mounted inside the pedestal base. Press here to see a schematic diagram of the installation. The 3-D Zoetrope, first prototype, was exhibited in the SIGGRAPH 2000 Art Gallery, July 23-28, 2000, New Orleans, Louisiana. Following this, it was on exhibit at the Art Gallery of the Institute for Studies in the Arts, Arizona State University.

Press here for maintenance procedures for the 3-D Zoetrope.