Low cost finger tracking for a virtual blackboard

Abstract

This paper presents a complete and inexpensive system to track the movements of a physical pointer on a flat surface. Any opaque object can be used as a pointer (fingers, pens, etc.) and it is possible to discriminate whether the surface is being touched or just pointed at. The system relies on two entry-level webcams and it uses a fast scanline-based algorithm. An automatic wizard helps the user during the initial setup of the two webcams. No markers, gloves or other hand-held devices are required. Since the system is independent from the nature of the pointing surface, it is possible to use a screen or a projected wall as a virtual touchscreen. The complexity of the algorithms used by the system grows less than linearly with resolution, making the software layer very lightweight and suitable also for low-powered devices like embedded controllers.