可適用配戴鏡者之三維視線追蹤系統

視線追蹤系統的目的是要偵測人類眼睛注視的方向。藉由追蹤人類眼睛視線，可明確得知使用者感興趣的事物，並可提供使用者與電腦間新的溝通方式，因此視線追蹤一直是一個重要的研究議題。但是在大多數視線追蹤的研究中，皆未探討鏡片所帶來的折射問題，所以這些方法並不適用於追蹤配戴眼鏡者的視線。在本篇論文中，我們提出了一套可適用於配戴鏡者之三維視線追蹤的方法。此方法需利用校正過的雙攝影機以及至少兩顆以上的近紅外線點光源，即可在允許使用者頭部可自由移動的情形下，透過眼鏡鏡片追蹤使用者的視線。利用透鏡幾何光學的特性以及眼睛特徵的反射特性，攝影機可攝得點光源經眼鏡鏡片折射後在角膜反射形成的亮點以及經角膜與眼鏡鏡片折射後的瞳孔輪廓。藉由此兩種特徵以及雙攝影機立體視覺原理，便可計算出使用者之視線方向。我們藉由程式模擬觀察在未受雜訊干擾的情況下，透過 100 ∼ 850 度的近視鏡片模型，估測視線方向。實驗結果顯示我們所發展的視線追蹤方法具有高度可行性。

關鍵字

三維視線追蹤；透鏡幾何光學；鏡片折射；非侵入式；頭部自由移動

並列摘要

The goal of a gaze tracking system is to detect user's fixation point. This technique not only can improve the pointing device efficiency but also can provide direct estimate of the point of interest of a user. Due to the potential of developing new man-machine interaction models, the gaze tracking problem is always an important research issue. However, in most of the gaze tacking studies, the influence of eyeglasses is not considered so that those kinds of techniques are not applicable to people wearing eyeglasses. In this these, we proposed a new gaze tracking method suitable for estimating the 3-D line of sight of a person wearing eyeglasses. We show that if the lens position and orientation is known, 3-D gaze tracking through eyeglasses with free-head movement is possible by using two calibrated stereo cameras and two calibrated near infrared point light sources. This method is developed based on the geometrical optics of the eyeglass and the human eye. The stereo cameras are used to acquire the corneal reflections of the point light sources and the refracted pupil boundary points. Then, the refraction of the eyeglasses is compensated so that the 3-D line of sight can be estimated accurately. Computer simulations of eyeglasses with diopters ranging from 1.0 to 8.5 have been conducted to verify that the proposed method is applicable. The experimental results show that our method is very promising.