1. A method for estimating an eye gaze direction as a vector from a fovea of an eye, through a center of an iris, to an object upon which gaze is directed, based on a facial image, comprising: receiving facial image by at least one processor, and based on at least the facial image, an anatomical model of the eye, and an adaptive computational model stored in a memory: estimating the center of the iris; iteratively seeking a best estimate of at least: a three dimensional center and size of the eye to thereby define an optical axis through the center of the iris and the three dimensional center of the eye; a position of the fovea of the eye, displaced from the optical axis of the eye; estimating an eye gaze direction along the vector; and receiving calibration information representing an error between the estimated eye gaze direction and a gaze target; updating the adaptive computational model to reduce the error; and outputting information selectively dependent on the estimated eye gaze direction.