Those early experiments in capturing the essential motion of the body
have evolved into a number of different technological strands. Much of the
early work was developed on the Amiga computer, the first affordable platform
capable of dealing with a video signal in any realistic way. At least two
body sampling systems were developed on the Amiga. Mandala used a standard
Amiga with a Live! board to analyse an incoming video signal and generate
pixel-pattern based triggers. The system was, at best, slow and clunky but
it worked, as long as its limitations, particularly its speed limitations,
were taken into account at all times. The system tended to be rather unpredictable,
and certainly very environmentally sensitive and extremely light-dependent
(a drawback of all such video-based systems).
A system similar to Mandala was developed at the Institute for Studies in the Arts at Arizona State University, Tempe. This system, on which I worked in the early nineties, was taken considerably further than Mandala, ported to the Silicon Graphics platform, and, with the addition of a second camera, became three-dimensional. For a more indepth description of this system, and the work of ISA in body sampling systems, see Lovell/Mitchell 1995.
These video-based systems work well in certain circumstances, and for particular kinds of work. While they are generally incapable of capturing gestural nuance, the flick of a wrist, the bend of an ankle, the blink of an eye, they do work well in capturing gross movement in gathering the sense of the movement on stage (or wherever), in understanding the range of motion by one or more performers (or interactors in an installation context). These systems are capable of working with ensemble as well as with solo performers, and are perhaps unique in this regard.
This technology is by no means the only way to capture human motion,
however. A number of researchers have devised methods of placing sensors
directly on the body, or of placing sensors close to the body, to detect
motion. Among such systems are infra-red distance-sensing mechanisms (similar
to home security motion-sensing systems); body suits, in which sensors are
placed directly on the body; and other kinds of hardware sensors such as
photoelectric cells and ultrasonic sensors. For an excellent primer on physical
sensors and computers, visit Dan O'Sullivan's site at http://www.itp.tsoa.nyu.edu/~alumni/dano/physical/physical.html.
Among these systems, perhaps the most successful is the MidiDancer
system developed by Mark Coniglio
and Dawn Stopiello.
"MidiDancer consists of eight sensors built into a costume and placed at strategic locations around the body, e.g., the elbow or knee. As these joints bend, the movement of the sensors is measured by a tiny microcomputer and the information encoded into a form that can be sent via a radio transmitter. Offstage there is a receiver/decoder which is connected to a Macintosh computer running a software called Interactor. Interactor has been pre-programmed to look for particular
movements and, in response, to send commands to MIDI synthesizers, lighting controllers, LaserDisc players, etc." (from the troika ranch website)
With my early interest in placing music in "non-musical" environments such as theatre, dance, installation, video, and, more recently, in screen-based interactive work, it seems inevitable that I would be drawn to experiment with these systems in which the mark of the body is central. My own early experiments included working with ultrasonic systems, including the Mattel PowerGlove , with an ultrasonic distance-sensing system designed by a research group at York University in England, as well as with the ISA/ASU Amiga-based system. All of these systems had their advantages and drawbacks and all generated considerable amounts of spurious data, seeing phantoms and spirits not visible to the limited imaginations and poor eyesight of a simple musician. Those data, however, were a breakthrough, and led me to begin working with the instabilities of all these systems as a positive force, finding, with apologies to Walter Benjamin, an interactive "a-ha" moment which changed my compositional life forever.