In this dissertation, a new approach for determining gaze direction is presented. This
approach is based on the existence of a visual axes center for the human eye, the location
of which is invariant with respect to the head. The vector from the visual axes center of
an eye through the pupil center provides a reliable approximation for a gaze vector.
Calibration camera images of human subjects looking at known points on a computer
monitor are collected in a non-intrusive manner. Algorithms are applied to the images
from two independent cameras whose spatial relationship is known with respect to the
monitor. The calibration algorithms allow determination of physical distances between
selected facial features visible in the images and the invariant location of the visual axes
center for each eye (not visible) with respect to these features. Given these invariant
relationships between a subject's facial features and eye visual axes centers, optimization
techniques are applied to subsequent images collected from a single camera to obtain the
three-dimensional locations of the visible facial features and the visual axes centers, and
from these, the gaze direction.
The results of experiments conducted to determine the viability and accuracy of the
visual axes center approach in determining the gaze direction are presented. The results
show that the approach can provide acceptable gaze direction error values when high
accuracy (< 1° angular error) is not required. Techniques to improve accuracy are
discussed as well as potential limitations of the approach
