VISUAL AXIS MEASURING APPARATUS AND METHOD, VISUAL AXIS MEASURING PROGRAM, AND RECORDING MEDIUM RECORDING THE SAME

摘要

PROBLEM TO BE SOLVED: To construct visual axis measuring techniques for measuring the direction of gazing without the user being stressed or wearing a special device. SOLUTION: An apparent pupil position is detected from an image taken with a camera and the direction of refraction of light going from the camera to the apparent pupil position is calculated to determine contour coordinates located at a specific distance from the center of curvature of the cornea along the direction of refraction, to thereby estimate the actual pupil position. A reflected image of external light on the surface of the cornea is detected to detect the position of the cornea's center of curvature which is located on a straight line passing through the center of the camera and the reflected image and which is away from the reflected image by a distance equal to the radius of curvature of the cornea. The center of the pupil is detected from the actual pupil position and the user's visual axis is calculated on the basis of a straight line connecting the center of the pupil to the center of curvature of the cornea. The conversion term of the visual axis is calculated from the coordinates of a plurality of reference points and from the visual axis calculated at the time when the user gazes at the reference points, and the visual line is corrected using the conversion term.