Eye-tracking and head-tracking techniques have been applied in many fields, including human–computer interaction, gaming, virtual reality (VR), and the medical. In these applications, users must wear special hardware devices such as eye trackers and head-mounted devices. However, these devices are high-priced, operating them may be complicated, and users may feel uncomfortable wearing them. Then, how can we track eye movements and head movements in real time without these devices? In this paper, we present a real-time camera-based gaze-tracking system that provides two interactive modes: eye gaze and head gaze. The system uses the same calibration procedures to project the gaze directions of the eyes or head to the screen coordinates. Then, we designed a 9-point circular interface to examine the accuracy. Eye gaze and head gaze achieved a visual angle error of 1.76 and 2.65 degrees, respectively. They were comparable to commercial eye-trackers. We also applied the system to a game and verified its effectiveness in the realm of interaction by analyzing the user experience and game score under different interactive modes. The experimental results showed users could get a similar score as the keyboard using eye gaze and feel more immersive under head gaze. Our findings can help to provide more funny choices for users to interact with computers.
