視線追蹤是個廣泛應用在人機互動上的技術，在偵測到使用者視線所看的方
向後，視線與目標所在平面的交點即為注視點(使用者所注視位於平面上的點)。
在此方法中有一個較特別的假設：將虹膜的輪廓視為橢圓，而不是視為圓。
除此之外，我們的方法在執行過程中只需要利用到一隻眼睛。經由一些影像處理
的技術和利用三維空間中圓與橢圓的幾何特性，我們可以決定唯一的視線。
在此論文中我們證明了圖片在低解析度的情況下，實驗結果的準確率會比在
高解析度的情況下低。此外，眼瞼過於明顯的部分也會導致結果的誤差。然而，
不論在解析度或是眼瞼的影響之下，我們都能夠穩健地將計算出的所有注視點區
分成四個區域。

Eye gaze tracking is a technique which is commonly used in human-computer
interaction. By determining the eye gaze, the point-of-regard can be estimated by intersecting the gaze line and the target plane.
A particular assumption is that irises are regarded as ellipses rather than circles in our approach. Besides, only one eye is required in the processes of the approach. The unique eye gaze can be computed via some image processing techniques and exploiting geometric properties of circles and ellipses in the 3D space.
In this thesis we show that with low resolution images, the accuracy of the
results is reduced than with high resolution ones. Furthermore, conspicuous eyelid edges may lead the results to be unsatisfied. However, four distinct clusters can be separated robustly with both the influences of resolution and eyelids.

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