reacTIVision: a computer-vision framework for table-based tangible interaction

This article provides an introductory overview to first-time users of the reacTIVision framework -- an open-source cross-platform computer-vision framework primarily designed for the construction of table-based tangible user interfaces. The central component of the framework is a standalone application for fast and robust tracking of fiducial markers in a real-time video stream. The framework also defines a transport protocol for efficient and reliable transmission of object states via a local or wide area network. In addition, the distribution includes a collection of client example projects for various programming environments that allow the rapid development of unique tangible user interfaces. This article also provides a discussion of key points relevant to the construction of the necessary table hardware and surveys some projects that have been based on this technology.