reacTIVision is an open source, cross-platform computer vision framework for fast and robust tracking of fiducial markers attached onto physical objects, as well as for multi-touch finger tracking. The Reactable applies reacTIVision to create an electro-acoustic computer music instrument with a tangible user interface.

Robert Moog played an early prototype of the Reactable at the NIME conference 2004 in Hamamatsu, Japan.
It was mainly designed as a toolkit for the rapid development of table-based tangible user interfaces (TUI) and multi-touch interactive surfaces. This framework has been developed by Martin Kaltenbrunner and Ross Bencina  at the Music Technology Group at the Universitat Pompeu Fabra in Barcelona, Spain as part of the the reactable project, a novel electro-acoustic music instrument with a tangible user interface.