Flashlight tracking

Flashlights are cheap, robust, fun, familiar and safe and so make interesting interaction devices for the public. We have developed a system for visually tracking flashlights that allows users to shine them onto a surface in order to trigger sounds that are associated with different features and target areas.

Visual tracking involves extracting features of the image of the beam on the surface, including its centroid and area, from a video view in real time. We have also developed a tool for interactively defining targets on a video view of the surface. The above image shows an interactive poster. Shining a flashlight on a planet causes an audio commentary to be replayed. This device is primarily aimed at public settings such as museums, exploratoria, exhibitions, foyers and classrooms, where users might want an intuitive and engaging way of acquiring information by pointing at walls, ceilings, artifacts, tapestries, posters and other wall displays. It also has potential for use on the city streets at night. We have developed three applications of visually tracked flashlights: controlling graphical objects that are projected onto the surface of the Storytent portable immersive display; enabling children to create interactive wall posters; and triggering ghostly voices when exploring a series of caves underneath Nottingham Castle. The third of these was experienced by over two hundred members of the public. Enhanced images of the three caves Flash Light We are currently extending our approach by identifying additional information that can be extracted from the image of a flashlight beam. For example, a recent extension to the system enables it to recognise individual flashlights from their beams alone so that different flashlights can trigger different information. The following image shows the system classifying and tracking two different flashlight beams.