Glint features have important roles in gaze-tracking systems. However, when the operation range of a gaze-tracking system is enlarged, the performance of glint-feature-based (GFB) approaches will be degraded mainly due to the curvature variation problem at around the edge of the cornea. Although the pupil contour feature may provide complementary information to help estimating the eye gaze, existing methods do not properly handle the cornea refraction problem, leading to inaccurate results. This paper describes a contour-feature-based (CFB) 3-D gaze-tracking method that is compatible to cornea refraction. We also show that both the GFB and CFB approaches can be formulated in a unified framework and, thus, they can be easily integrated. Furthermore, it is shown that the proposed CFB method and the GFB method should be integrated because the two methods provide complementary information that helps to leverage the strength of both features, providing robustness and flexibility to the system. Computer simulations and real experiments show the effectiveness of the proposed approach for gaze tracking.

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This paper proposes an adaptive learning method for tracking targets across multiple cameras with disjoint views. Two visual cues are usually employed for tracking targets across cameras: spatio-temporal cue and appearance cue. To learn the relationships among cameras, traditional methods used batch-learning procedures or hand-labeled correspondence, which can work well only within a short period of time. In this paper, we propose an unsupervised method which learns both spatio-temporal relationships and appearance relationships adaptively and can be applied to long-term monitoring. Our method performs target tracking across multiple cameras while also considering the environment changes, such as sudden lighting changes. Also, we improve the estimation of spatio-temporal relationships by using the prior knowledge of camera network topology.

Abstract-To track targets across networked cameras with disjoint views, one of the major problems is to learn the spatio-temporal relationship and the appearance relationship, where the appearance relationship is usually modeled as a brightness transfer function. Traditional methods learning the relationships by using either hand-labeled correspondence or batch-learning procedure are applicable when the environment remains unchanged. However, in many situations such as lighting changes, the environment varies seriously and hence traditional methods fail to work. In this paper, we propose an unsupervised method which learns adaptively and can be applied to long-term monitoring. Furthermore, we propose a method that can avoid weak links and discover the true valid links among the entry/exit zones of cameras from the correspondence. Experimental results demonstrate that our method outperforms existing methods in learning both the spatio-temporal and the appearance relationship, and can achieve high tracking accuracy in both indoor and outdoor environment.Index Terms-Brightness transfer function, camera network, non-overlapping cameras, spatio-temporal relationship, visual surveillance, visual tracking.

Glint features have important roles in gaze tracking systems. But when the operation range of a gaze tracking system is enlarged, the performance of glint-feature-based (GFB) approaches will be degraded mainly due to the curvature variation problem at around the edge of the cornea. Although the pupil contour feature may provide complementary information to help estimating the eye gaze, existing methods do not properly handle the cornea refraction problem, leading to inaccurate results. This paper describes a contour-feature-based (CFB) 3-D gaze tracking method that is compatible to cornea refraction. Experiments show the effectiveness of the proposed approach for gaze tracking.