In the fall of 2005 I began a collaboration with choreographer Kathleya Afanador and composer Allen Fogelsanger to create an interactive dance performance for Cornell University's 2006 Spring Dance Concert. Over the next several months I worked with the team to implement a near-realtime motion-capture system using a blend of COTS software and hardware and some proprietary "glue" code, and to define the visuals that would accompany Kathleya's choreography and Allen's soundscape.
We chose the EyesWeb 3.0 CV software to power our computer vision system. We originally intended to use a four-channel PCI framegrabber to digitize video from two security cameras but due to some form of hardware incompatibility with the host PC, we fell back to using a single Firewire digital video camera. An Eyesweb patch used background-subtraction to isolate the forms of the five movement artists performing the piece and then determined rectangular bounding-boxes surrounding each performer. Additionally, each performer wore a brightly-colored leotard of a different color; the Eyesweb patch tracked these colors to match each performer to her bounding rectangle. This data was streamed across a LAN to a server implemented in Java which forwarded the data to the systems responsible for generating audio and video output to accompany the performance.
I implemented the graphics rendering system for Perimeter in the Processing development environment. The final system allowed a cue-list to control the display of several different visualizations of the dance. For example, vectors representing the motion of the center of mass and each bounding box corner point were computed and displayed. Additionally, circles representing the centers of the color-tracked regions were displayed. Behind these graphics, pre-rendered video files were displayed.
The final output was front-projected onto a 60'x30' black scrim hung in the first bay of the proscenium theater, in front of the performers. Since all light falling on the performers came from behind the scrim, it was essentially transparent except for the areas on which the graphics were projected.
Design ©2005-2007 R. Spicer / Alterscapes.
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