Dopplerdanse: Some Novel Applications Of Radar

farther apart than they were in the original byte map. If this condition were not imposed, the views produced would be both larger in height and width than the original and would appear sparse. Results Figure 2 shows the original image, and Fig. 3 shows the right and left views for that image. Note how the new images appear blurry and distorted compared to the original. When viewed with either a stereographic viewer or via a suitable projection method, one can easily see the effect of the process. One benefit of this method is that once a suitable color look-up table has been created for an initial image, the same table can be used for the right and left views, thus reducing the amount of experimentation necessary in the choice of a suitable table. The image generated is not a pure surface map, but rather is much more akin to a 3-D histogram viewed 'top-down', where only the tips of the bars are visible . A more traditional orthogonal view had been considered but was dismissed as this would have entailed more coding and a slower process. In addition viewing the data set topdown is much more similar to viewing the set in 2D. Conclusions This method fills a small but important need for the artist because it allows direct viewing ofa 3-D image as opposed to requiring the use of a true projective technique. It does not solve all viewer requirements, but can successfully act as an aid. Note 1. Readers can simulate the stereo effect by looking at the two viewsand crossing their eyes until the two halves merge. Care should be taken when attempting this. DOPPLERDANSE: SOME NOVEL APPLICATIONS OF RADAR Steve Mann, MIT, Room E 15-30, 20 Ames St., Cambridge, MA 02139, U.S.A. E-mail: steve@media.mit.edu Received 29January 1991. Acceptedfor publication !Jy RogerF. Malina. DopplerDanse [1] provides intimate connection between dancers and their movements through sounds created by the movements themselves . In performance, dancers move about, discover and improvise, evoking responses from each other (Fig. 4). The dancers' body movements actually produce the sound and control the lighting through the apparatus of DopplerDanse. The simplest version of the DopplerDanse apparatus consists of a number of X-band (10.525 GHz) radar motion-detectors that are used commercially for burglar alarms, automatic doors and automatic lights [2]. DopplerDanse differs from the classic theremin [3] in that it responds to movement rather than to absolute range, emphasizing dynamics rather than static body positioning. It is also highly intuitive. 'Fast' things, such as electric drills, produce high-pitched sounds, while slow-moving objects produce lower pitches. With DopplerDanse , when a dancer moves quickly, a comparatively high-pitched squeal of sound is produced; a dancer's slow movements result in a deep growl. Acceleration produces chirps. The whole Doppler sound spectrum is produced in a dancer's walk toward one of the radar units: the dancer's body creates a deep growling sound, yet over that sound can be heard a periodic chirping caused by arms swinging back and forth. The radar signals may be further processed for sound variety-or the sound can be quantized to fall on specific musical notes, if more conventional musical sounds are desired. Alternatively, a rhythm generator may be triggered or clocked by quanta of Doppler. A mapping of Doppler can be adapted based on specific body gestures . For example, a bank of 12 directional radar units can be mapped to allow dancers to 'grab' a note from one unit with a hand gesture without affecting the others. The gestural velocity controls the amplitude of the note. In one performance , seven dancers with pale skin and white clothing created an octave by representing white piano keys, while the remaining five dancers with dark skin and black clothing represented black piano keys. Each dancer's movement sounded a different note. Simultaneous movements by the appropriate dancers produced chords. Very interesting spatial effects are possible through the use of three coherent radar units, with one unit in front of (or behind) the performer, Fig. 4. These dancers are performing with the aid of the apparatus of DopplerDanse...