Cross-Ratio Based Gaze Estimation using Polarization Camera System

Abstract

Eye-based interaction is one of the solutions for achieving intuitive interfaces on surfaces such as a large display, and thus, various eye-tracking methods have been studied. Cross-ratio based gaze estimation, which determines the point-of-gaze on a screen, has been studied actively as a novel eye-tracking method because the method does not require a hardware calibration defining the relationship between a camera and monitor. We expect that the cross-ratio method will be a breakthrough for eye-based interaction under various circumstances such as tabletop devices and digital whiteboards. In eye-tracking, near-infrared light is often emitted, and at least four LEDs are located on display corners for detecting the screen plane in the cross-ratio based method. However, long-time radiation of near-infrared light can make a user fatigued. Therefore, in this study, we attempted to extract the screen area correctly without near-infrared radiation emission. A polarizing filter is included in the display, and thus, visibility of the screen can be controlled by the light's polarization direction of the external polarized light filter. We propose gaze estimation based on the cross-ratio method using a developed polarization camera system, which can capture two polarized images of different angles simultaneously. Further, we confirmed that the point-of-gaze could be estimated using the screen reflection detected by computing the differences between two images without near-infrared emission.