Measurement of the rotation of a disk from its elliptical projection, with an application to eye movements
N. R. L. Bechai, Peter E. Hallett · Journal of the Optical Society of America · 1977
The elliptical projection of a circular disk, such as the pupil of the eye, on the plane face of a video camera can be used to measure rotation of the disk about a diameter, independently of any translational movements. The algorithm uses the intersections of any three equispaced video lines with the ellipse. Errors and system design are discussed.