Eye Tracking Essay

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Methods of Eye Tracking
A technique of recording eye position and movements is called oculography. There are four methods to track the motion of the eyes.
Electro-Oculography, In this method, sensors are placed on the skin around the eyes. This sensors measure an electric field exists when eyes rotate. By recording this small potential difference around the eye, the position of the eye can be estimated. This signal can change when there is no eye movement. This method is not useful for everyday use, since it requires the contact of electrodes around eye but is still used by clinicians. One of the advantages of this method is its ability to detect eye movements even when the eye is closed [4].
Scleral Search Coils, When a coil of wire placed …show more content…

This illumination appears as a glint on the cornea of the eye and is called as corneal reflection. This glint is used as the reference point for most of the existing work for gaze estimation. Whenever the head moves the glint will clearly change location, but when changing gaze direction occur it is less obvious that the glint shifts position. Merchant et al. in 1974 introduced the beginning work employing a single camera, a collection of mirrors and a single illumination source to produce the desired result [6)]. Yasuk Sugano et al. proposed a gaze tracking system which in coperate a single camera mounted on the monitor. The head pose of a person is estimated in this system by using a 3D rigid facial mesh [7]Ohno et al proposed a single camera system with a single glint [8]. Matsumoto et al. developed a system which computes the 3D head pose and estimate the 3D position of the eyeball using a single stereo system [9]. Wangand Sung also proposed similar approach[10]. Paul Smith et al. proposed a system with a single camera for monitoring head/eye motion for driver alertness [11] Chi Jian-nan et al developed a system consisting of active infrared source and a camera used for pupil tracking based on particle filtering . [12]. Laura Sesma et al. introduced a gaze tracking system based on a web cam and without using infrared light is a goal to widen the applications of eye tracking …show more content…

Narrow field camera is positioned at lower monitor corners which capture high resolution images king. Due to the narrow field of view head motion can be possible. [16]. Ke Zhang et al. proposed a 3D gaze tracking system with a pair of stereo cameras and two light sources [17].Reale et al. proposed a two camera system that detects the face from a fixed camera .which Estimates the location of eye region using an eye detector based on features of eye [18)].
2. Methods of Gaze Tracking
In gaze tracking first step is to estimate the position of eye from captured image and with this obtain result and information of head pose gaze is estimated. Two types of imaging processes are used in video-based eye tracking visible and infrared spectrum imaging. These methods are broadly classified into feature-based and appearance-based gaze estimation system
2.1Feature-based Gaze Estimation, Feature-based methods utilize the characteristics of the human eye to identify like limbus, pupil contour, eye comers and cornea reflections which are the common features used for gaze estimation. These features are generally less sensitive to variations in illumination and viewpoint [19] .The accuracy of this method decreases when accurate iris and pupil features are not available. There are two types of feature based methods exists [20] model-based and

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