Under the reactable Table: reacTIVision
To analyze the positions of the blocks in relation to each other, the reactable uses a computer vision (CV) system located under the tabletop surface. The CV setup is completely hidden within the machine and consists mainly of two important tools -- a camera and a projector.
Both the camera and projector point up toward the bottom of the tabletop, but they each serve a different purpose. The camera, which runs on a special vision engine called reacTIVision, looks up at the blocks and analyzes several factors:
- Which sides of the blocks are facing down on the table
- Where the blocks are in relation to the table's center
- Where the blocks are in relation to other blocks
- How the blocks are positioned around their own axis
- Any other tangible adjustments made on the table's surface that might alter pitch, filters and so forth
The reacTIVision engine takes all of these positions into account, analyzes the space and sends the information to a connection manager, which does two things simultaneously. First, it passes the reacTIVision's information to an audio synthesizer, which creates the sounds the musicians are attempting to play and pumps the music out to an output source. At the same time, the connection manager sends that same information to the projector, which also points up toward the underside of the tabletop. This projector isn't taking in information like the reacTIVision camera; instead, it paints the animations onto the blue, translucent tabletop, providing the players and spectators with the appropriate visual cues to match the music coming out.
The students who made the reactable give demonstrations at music festivals, conferences and museums fairly often, so if you want to see a live performance, check the reactable's Web site for upcoming appearances. Of course, if you want to buy one for yourself, there are plans to bring the reactable to the market. (Unfortunately, no one has mentioned a price tag.) If all else fails, you could always check out Björk on tour if she still happens to favor the synthesizer and stops by your area. For lots more sonically appealing information on music and music technology, filter through the links below.
Related HowStuffWorks Articles
More Great Links
- Andrews, Robert. "ReacTable tactile synth catches Björk's eye -- and ear." Wired. August 9, 2007. (Nov. 24, 2008) http://www.wired.com/entertainment/music/news/2007/08/bjork_reacTable
- EARS: ElectroAcoustic Resource Site. "Electroacoustic music." (Dec. 1, 2008) http://www.ears.dmu.ac.uk/spip.php?rubrique125
- Jordà, Sergi, Günter Geiger, Marcos Alonso and Martin Kaltenbrunner. "The reacTable: exploring the synergy between live music performance and tabletop tangible interfaces." Music Technology Group, Pompeu Fabra University. 2007. (Nov. 24, 2008) http://mtg.upf.es/reactable/pdfs/reactable_tei2007.pdf
- Jordà, Sergi, Günter Geiger, Marcos Alonso and Martin Kaltenbrunner. "The reacTable: a collaborative musical instrument." Music Technology Group, Pompeu Fabra University. 2006. (Nov. 24, 2008) http://mtg.upf.es/reactable/pdfs/reactable_tice2006.pdf
- Kaltenbrunner, Martin and Ross Benica. "reacTIVision: a computer-vision framework for table-based tangible interaction." Music Technology Group, Pompeu Fabra University. 2007. (Nov. 24, 2008) http://mtg.upf.es/reactable/pdfs/reactivision_tei2007.pdf