Method for detecting point of gaze and device for detecting point of gaze

摘要

A gaze point detection device 1 has four cameras 2a, 2b, 2c, 2d, light sources 3a, 3b, 3c, 3d, control circuits 4, 5, 6, and an image processor 7. The image processor 7 calculates vectors r, each of which is from a corneal reflection point to the center of a pupil, on a plane that is vertical to base lines. The image processor 7 also calculates angles θ of the line of sight on the basis of the vectors r and by using a function f including M parameters. Moreover, the image processor 7 determines the M parameters based on the angles θ, and detects a point of gaze Q based on the line of sight direction calculated using the determined parameters. The number of cameras is set at M×½ or higher.

主权项

1. A gaze point detection method, comprising:
a face image generation step of generating face images of a subject by using an N number of cameras (wherein N is a natural number of 2 or more) and a plurality of light sources; a vector calculation step of calculating vectors r based on the face images generated by the N number of cameras, the vectors r each representing an actual distance between a center of a pupil of the subject and a corneal reflection point on a cornea of the subject on which light from the light sources reflects; a line of sight direction calculation step of calculating angles θ of a gaze of the subject with respect to base lines connecting the center of the pupil and the N number of cameras, based on the vectors r corresponding to the N number of cameras, by using the following formula (1) in use of a function f and an M number of undetermined constants (wherein M is a natural number of 3 or more) including at least an offset vector r0 of each of the vectors r;
θ=f(|r−r0|)  (1) an undetermined constant determination step of determining the M number of undetermined constants included in the function f, by using a plurality of relational expressions that are derived based at least on the angles θ calculated with respect to the N number of cameras; wherein the line of sight direction calculation step calculates the angles θ using the following formula (2) that includes a coefficient k and the vector r0 as the undetermined constants;
θ=k|r−r0|  (2), and the undetermined constant determination step determines the coefficient k and the vector r0; and a gaze point detection step of detecting a point of gaze of the subject on the basis of the line of sight direction calculated in the line of sight direction calculation step, by using the M number of undetermined constants determined in the undetermined constant determination step, wherein the number N of cameras is set at M×½ or higher; the vector calculation step calculates vectors r corresponding to at least three cameras among the N number of cameras when the subject is caused to gaze at one specified point on a predetermined plane, the undetermined constant determination step derives three relational expressions each including the coefficient k and the vector r0, by applying the vectors r calculated by the vector calculation step, and the angles θ calculated corresponding to at least three cameras, to the formula (2), and determines the coefficient k and the vector r0 by establishing simultaneous equations with the three relational expressions.