The precision of point-of-gaze (POG) estimation during
a fixation is an important factor in determining the usability of
a noncontact eye-gaze tracking system for real-time applications.
The objective of this paper is to define and measure POG fixation
precision, propose methods for increasing the fixation precision,
and examine the improvements when the methods are applied
to two POG estimation approaches. To achieve these objectives,
techniques for high-speed image processing that allow POG sampling
rates of over 400 Hz are presented. With these high-speed
POG sampling rates, the fixation precision can be improved by
filtering while maintaining an acceptable real-time latency. The
high-speed sampling and digital filtering techniques developed
were applied to two POG estimation techniques, i.e., the highspeed
pupil–corneal reflection (HS P-CR) vector method and a
3-D model-based method allowing free head motion. Evaluation
on the subjects has shown that when operating at 407 frames per
second (fps) with filtering, the fixation precision for the HS P-CR
POG estimation method was improved by a factor of 5.8 to 0.035◦
(1.6 screen pixels) compared to the unfiltered operation at 30 fps.
For the 3-D POG estimation method, the fixation precision was
improved by a factor of 11 to 0.050◦ (2.3 screen pixels) compared
to the unfiltered operation at 30 fps.