Directing Tangible Controllers with Computer Vision and Beholder.

We present Beholder, a computer vision (CV) toolkit for building tangible controllers for interactive computer systems. Beholder facilitates designers to build physical inputs that are instrumented with CV markers. By observing the properties of these markers, a CV system can detect physical interactions that occur. Beholder provides a software editor that enables designers to map CV marker behavior to keyboard events; thus connecting the CV-driven tangible controllers to any software that responds to keyboard input. We propose three design scenarios for Beholder—controllers to support everyday work, alternative controllers for games, and transforming physical therapy equipment into controllers to monitor patient progress.