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One of the fundamental questions at the heart of an interactive performance is always how direct and palpable are the relationships between two interacting forces. How clear should the relationships be for the uninformed viewer? Naturally any answer to this question presupposes a lot about the potential audience. In the case of e-Motion the expectation was that most visitors to the exhibition would be seeing this technology for the first time, and would not have preconceived notions about what an interactive dance performance should be. It seemed likely that many would saunter through the museum at a fairly steady pace without pausing to observe any particular exhibit for very long. Since I did indeed want to make the viewer aware of the fact that the dancer had control over the music at some level, and keeping in mind my notion of who the average visitor would be, I sought to make these relationships as clear as possible and chose to establish readily observable 1:1 correspondences between the dancer and the music. In previous interactive dance performances where I have used more convoluted algorithmic processes for creating interaction, the majority of audience members have been almost entirely oblivious as to how the interaction was taking place, even when I have written extensive program notes to explain the kinds of interaction that were occurring. Which begs the question—why bother with the live interactive technology at all, when a recording of anything other than a static sine wave tone might achieve the same result through pure and simple chance? Therefore, using clearly presented connections seemed the best choice for the project.
The 1:1 correspondences that were employed included the dancer's kinesthetic motion as a control for amplitude, duration, and total note events. As the dancer's total kinesthetic motion for each of the eight quadrants was calculated every two seconds, the value from this calculation would replace the previous as the new amplitude for all note events triggered by the dancer's motion within the same quadrant. This new amplitude would only be reached one and a half seconds after it became the new value, in the intervening time there would be a gradual ramp of values to smooth out any sharp transitions that were the result of taking a tally of the kinesthetic motion every two seconds instead of in smaller increments.
The picture below is of a Max subpatcher for calculating total kinesthetic motion
Although the general term "amplitude" is being used here to refer to the acoustical loudness of the actual sound, what it really refers to in the context of the algorithms employed are MIDI attack velocity messages; these messages may control (among other things): loudness, timbral spectrum, proximity, modulation, etc. Since MIDI attack velocity messages are in a range of 128 possible values, a simple multiplication operation was used to scale the total kinesthetic motion to a usable quantity. Kinesthetic motion was also used in a similar manner to control the duration of any notes being triggered within the same quadrant. However, unlike the calculation for amplitude, duration was considered in inverse proportion to the total kinesthetic energy for the quadrant so that the more motion that occurred the shorter the durations became.
Duration was inversely proportional to the total kinesthetic activity for a particular quadrant.
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Note events were triggered by changes in zone values (the result of Cyclops detecting changes in light intensity through its difference threshold analysis) and were therefore the direct result of the dancer's motion. By moving with isolation and poise the dancer could initiate note events very precisely, and by making larger sweeps and gestures they could create huge washes of sound. In fact, it was fascinating to hear how a conscientious dancer could sound distinctly different from an untrained mover; inevitably they sounded less random.