Abstract: Systems and methods for determining an optical axis vector of an eye in a three-axis coordinate system. An ellipse equation defining an iris disc corresponding to the eye, is determined on an XY plane of the three-axis coordinate system. A set of equations is derived based on the ellipse equation corresponding to a plurality of edge points of the iris disc in the three-axis coordinate system. An estimated iris diameter is iteratively calculated until a difference between the estimated iris diameter and a predetermined iris diameter is less than a threshold. The iterative calculation includes calculating a composite optical axis vector of the eye in the three-axis coordinate system based on solutions for the iris diameter.

Abstract: Systems and methods for tracking a head position of a user include obtaining digital images of the user's head, processing the images to locate anatomical structures beneath the visible surface, and using those determined locations as inputs to a computing device. In an embodiment, images of a user's face are processed to identify the irises of the eyes, identify pixels along a boundary between each iris and the surrounding sclera, determine an ellipse defined by the identified iris-sclera boundary pixels, determine a distance-to-pixel ratio based on a pixel length of a long axis of such an ellipse compared to a known or presumed diameter of the iris, locating the iris in a three-axis coordinate system, determining an optical axis vector of the eye in the three-axis coordinate system, and calculating a center of the eyeball based on the optical axis vector and a known or presumed eyeball radius.

Abstract: Systems and methods for tracking a head position of a user include obtaining digital images of the user's head, processing the images to locate anatomical structures beneath the visible surface, and using those determined locations as inputs to a computing device. In an embodiment, images of a user's face are processed to identify the irises of the eyes, identify pixels along a boundary between each iris and the surrounding sclera, determine an ellipse defined by the identified iris-sclera boundary pixels, determine a distance-to-pixel ratio based on a pixel length of a long axis of such an ellipse compared to a known or presumed diameter of the iris, locating the iris in a three-axis coordinate system, determining an optical axis vector of the eye in the three-axis coordinate system, and calculating a center of the eyeball based on the optical axis vector and a known or presumed eyeball radius.

Abstract: A concave reflector is shaped to receive energy emanating from a signal source positioned at the reflector's vertex and to reflect all received energy in a uniform output direction. The reflector additionally introduces a designated constant phase shift into all reflected energy relative to unreflected energy from the signal source, regardless of where the received energy impinges upon the reflector. When the source signal is periodic, this reflector design minimizes near field interference between the reflected signals, since they all have the same phase shift relative to the unreflected source signal. Furthermore, if the reflector is designed to implement zero phase shift, reflected and non-reflected signals tend to combine additively in the far field, focusing most of the transmitted energy toward the center of the transmission pattern.

Abstract: The tracker determines a vision vector for an eye of an operator. The device generally comprises: a video camera oriented so as to observe an eye of an operator for obtaining an image of the eye; camera interface electronics and image processor for digitizing the image of the operator's eye and for analyzing the digitized image for determining therefrom a plurality of points determinative of the iridal ellipse, the points being on the boundary between the eye's sclera and iris as represented by different light intensities; and a processor for utilizing said information and an estimate of the diameter of the iris in formulating an estimated optical axis vector for the eye. If the position and orientation of the camera is known relative to the operator's eye, then the pupillary ellipse can be used instead of the iridal ellipse. The tracker of the invention can be used as a mouse emulator attached to a mouse port of a personal computer system.