Discussion Group on Gesture Research in Music

			Gestural Capture Techniques

		Instrumental Gesture

If we focus on the case of instrumental gestures, one can divide gestural capture techniques according to the following capture strategies: (Depalle et al., 1997)

One can use different sensors in order to capture different gestures or movements. These sensors may or may not need physical contact to transduce the gesture(s) into electrical signals. If physical contact is involved, they can be called Haptic; otherwise, Non-Haptic. (Baecker et al., 1995) The sensors can, in turn, be classified as to whether the sensor outputs are continuous or discrete values of the variable sensed.
An attempt has been made at IRCAM to generate a classification of the most common sensors according to these categories. The result is shown in a web page available from the IRCAM Pedagogy department; it is intended as an aid for composers seeking to work with gestural capture at IRCAM.
We consider these techniques as direct gestural acquisition, since one is capturing the actual physical gesture or movement through the sensors.
Another approach is to look for the gesture in the sound produced by an instrument (Bailey et al., 1993). It is well known that the sound produced by an acoustic instrument is a direct result of the physical properties of the instrument, the acoustics of the room where the instrument is being played, and the gestures applied to generate the sound by the performer. If we can isolate the influence of the room and also know the physical behaviour of the instrument, it is then possible to deduce information about the gestures used to produce the sound from its analysis. We have called this indirect gestural acquisition.
Although it is usually harder to perform than direct acquisition -- expensive processing power, complicated algorithms necessary to identify different gestures, etc. -- indirect acquisition has the potential to give a better result than direct acquisition, since the sound contains the whole gestural information that caused it.

		Non-Instrumental Gesture

In the case of non-instrumental gestures, most of the capture systems use sensors or video cameras (in the case of sign language acquisition, BigEye system from Steim, etc). For a quick survey, check out the webpages of A. Mulder and D. Rodger

Add your examples, description of different technologies--send us an email with links, etc.!