Author: John Harrison
Download full paper: Media:Using Pd to create a Visualization Instrument for Percussion.pdf
Many contemporary composers are currently exploring the use of live visualizations to enhance already-existing aural-based compositions. The challenges are considerable: Artistically, how can visualizations enhance rather than detract from the music and the performers? Technically, how can the visualizations be described in a way which easily allows specificity, offers a rich set of possibilities, and yet offers a rich context for expression? An environment for visualizations needs be carefully designed. Otherwise it is too easy for it to be compared with (and nor more effective than) the many visualizations already existing in readily-available free audio players, such as Windows Media Player.
Hack.Art.Lab (HAL), an art/technology collective based in Wichita, KS USA, recently collaborated with living composer Mary Ellen Childs to develop visualizations for her already-existing percussion work titled “Still Life”. Through high-level conversations with members of HAL and Mary Ellen Childs, I developed, programmed, then performed with our resulting instrument. The instrument is designed to enhance any already-existing percussive works, and we used “Still Life” for our proof on concept. It consists of a microphone, near-infrared LEDs to be attached to drum sticks, three modified webcams, and Pd[[Pure Data]] a dataflow programming environment.
Artistically, HAL and Mary Ellen Childs agreed to explore a completely synthetically generated environment, non-deterministic in nature, and yet with organic, living, natural qualities. We wished to stay away from obvious visual associations, preferring instead to explore abstract qualities so as not to have content that was too specific as that could detract from already-existing compositions. We wanted something which felt “alive” and which would offer unpredictable variety within a tight set of constraints. In this way, our visualization instrument is analogous to a more traditional acoustic instrument.
To realize our ideas, I used pmpd in Pd[[Pure Data]] a dataflow programming environment to describe the motion of an environment of spheres and lines rendered with Gem[[Tracking Motion Detection#Gem|Graphics Environment for Multimedia]] an OpenGL extension for →[[Pure Data|Pd]]. The environment was controlled by text files such that each text file would describe parameters and relationships to sound and motion of the players and the environment could respond accordingly. In listening to the music and watching the sticks of the percussion players, Pd[[Pure Data]] a dataflow programming environment could then create, destroy, animate, attract and repel the spheres and lines in organized, expressive ways. By creating new text files, it is also possible to create new visualizations for a different percussive work without changing the visualization instrument itself.
In creating the environment and preparing for the resulting performances, we explored options with modified wiimotes, multiple microphones, and various mounting options for our infrared LEDs and webcams. From a software perspective I developed ways of describing various types of manipulations as well as a few generically useful abstractions, such as an easy and transparent way for communication between Pd[[Pure Data]] a dataflow programming environment instances. In this paper I first explore our process of defining then tackling the high-level artistic and technical challenges. I then describe our technical problems and solutions regarding hardware and software. Finally, I evaluate the instrument in it current form, both artistically and technically, and I consider future development.
4th international Pure Data Convention 2011 Weimar ~ Berlin