Mirror-based high-speed gaze controller calibration with optics and illumination control

A precise calibration method for optical high-speed gaze controllers using rotational mirrors is proposed. The mirror-based pan/tilt camera can change gaze direction more quickly than a conventional pan-tilt-zoom camera, which actuates the camera itself. The high-speed gaze controller can track moving objects at high magnification and can utilize new applications of three-dimensional measurement. However, the controller is difficult to calibrate owing to shallow depth of field (DOF) at close focus positions and mechanical differences. We propose to control optics and illumination to detect calibration pattern control points precisely against shallow DOF; we deepen the DOF using a small aperture, coaxial episcopic illumination, and a retroreflective checkerboard pattern. We introduce mirror thickness for an exact gaze control model and bundle adjustment for large center-of-projection translation. We confirm that wide gaze range calibration is achieved more accurately than when mirror thickness is not considered.