Tracking Telescope Aiming Point for Bioptic Driving Surveillance

Bioptic telescope is a visual aid used by some people with impaired vision for driving and to qualify for licensing. Data on how and when bioptic drivers use the telescope and what they look at with it are important in bioptic driving studies. A video-based technique to track bioptic drivers’ spectacle frames, which represent telescope aiming point, is presented in this paper. With three retro-reflective markers pasted on the bioptic spectacles frame, aiming point is determined from the angles formed by the three markers. Telescope aiming points projected on a scene camera image is calculated by means of interpolation based on a novel calibration method in which a laser pointer is mounted on the spectacle frame. A large number of calibration points are sampled automatically when the driver scans across the scene. Preliminary experiment demonstrated that the average error over a 65° ×48° field was only 0.89 degree.