Table 1.

Comparison of previous and proposed methods for designing a gaze tracking camera.

Category	Method	Advantages	Disadvantage
Without a ground truth information for determining the viewing angle and DOF of the camera lens [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,22]	Wearable gaze tracking system [2,3,4,5], non-wearable gaze tracking system with a single camera [1,6,7,8,9,10,16,18,19,20], and multiple cameras [11,12,13,14,15,17,22]	Implementation time is short because the additional procedures of measuring the amount and velocity of user’s head movements are not necessary	Without determining the optimal viewing angle and DOF of the camera lens through empirical study, gaze tracking accuracy can be reduced or user’s head movement can be limited
With a ground truth information for determining the viewing angle and DOF of the camera lens (Proposed method)	The accurate amount and velocity of user’s head movements are measured with a web-camera and ultrasonic sensor for designing a non-wearable gaze tracking system with a single camera	Gaze tracking accuracy can be enhanced without limiting user’s head movements by determining the optimal viewing angle and DOF of the camera lens	Additional procedures for measuring the amount and velocity of user’s head movements are required