1. 2015-8-13 EIE426-AICV 1 Eye Tracking Techniques and applications eie426-EyeTracking-200903.ppt

2. Outline Part I :Physiology of the EYE Part II : Mechanism of Eye Movements Part III :Eye Tracking Technology Part IV :Eye Tracking Applications 2015-8-13 EIE426-AICV 2

3. How does our eye work 2015-8-13 EIE426-AICV 3

4. HOW DOES OUR EYE WORK Part I :Physiology of the EYE 2015-8-13 EIE426-AICV 4

5. 2015-8-13 EIE426-AICV 5

6. CAN YOU BELIEVE YOUR EYE Part II : Mechanism of Eye Movements 2015-8-13 EIE426-AICV 6

7. HOW EYE TRACKER WORKS Part III :Eye Tracking Technology 2015-8-13 EIE426-AICV 7

8. Outline 1. Current State and Application of Eye Gaze Tracking (EGT) Technology 2. Theory and the Classification of EGT Technology 3. The Framework of EGT system

9. Ⅰ. Current State and Application of Eye Gaze Tracking (EGT) Technology

10. What is EGT eye gaze——The line from the fovea through the center of the pupil is the line of sight (LoS). Usually, we take the optical axis as line of gaze (LoG). LoG can be approximate to LoS. In fact, LoS determines a person’s visual attention. eye gaze Tracking——By image Processing,if the LoG or LoS can be estimated, the point of regard (POR) is computed as the intersection of the LoG (or LoS) with the object of the scene or space. History and Development of EGT Interests of Visual attention can be traced back to 1897. At that time, it was a kind of diagnostic research, i.e. the recording of eye movement. Those technologies include ophthalmometer, Mechanical Method, Electro-Oculography (EOG), Optical-based Method, electromagnetic Oculography eye movement initially applied in medical research, such as brain and physiology analysis. with the development of Electronics, Computer and Image processing technology, further research focuses on Eye Gaze Tracking Technology.

11. Search Coil

12. A picture wearing the EOG apparatus

13. eye tracking techniques ： 1. Direct Observation ： ophthalmometer, peep-hole method 2. Mechanic Method ： use level to record eye movement 3. Optical-based Method ： Reflection Method （ mirror or prism ）、 Pupil- Corneal reflection 、 Purkinje Image 4. Electro-Oculography (EOG): recorded the difference in the skin potential 5. Electromagnetic Oculography ： The users gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field Except Optical-based Method, the above methods are more or less low accuracy or high intrusiveness. As a result, Modern Eye Gaze Tracking Techniques are mostly based on Optical-based Method. Ⅰ. Current State and Application of Eye Gaze Tracking (EGT) Technology

14. Ⅱ. Theory and the Classification of EGT Technology

15. Image-Based EGT Technology 1. Infrared Light : out of visible light; Paired with filter to eliminate the light of other wavelength ； 2. Eye camera :tracking eye movement and recording eye image sequence 3. Image Processing: detecting the visual elements 4. Further Estimation: 。 Having pre-processed, the data of eye gaze can be get from eye-movement model

16. System Framework Output Calibration Input Image acquisition Image Processing Feature Estimation Eye Tracking Data Estimation Ⅱ. Theory and the Classification of EGT Technology

17. Ⅱ. Theory and the Classification of EGT Technology Function of Each Module 1 Image acquisition: get bright pupil or dark pupil 2 Image Processing : Filtering,Noise reducing,difference,thresholding 3 Feature Estimation: Estimating the center of Pupil and corneal reflection 4 Eye Tracking: Estimation of eye gaze 5 Data Estimation: Algorithm validation,eye movement data analysis

18. Theory of EGT Technology 2D to detect the Optical Axis (basic) 2D to detect the Line of Sight (Advanced)

19. Classification of EGT Technology  view of humanity  View of appearance  view of application

20. Ⅱ. Theory and the Classification of EGT Technology From View of Humanity Usually By goggle, helmet … features ： high accuracy defects ： intrusiveness Remote Eye Tracker Usually on table features ： non-intrusive defects ： eye and head relative motion Head Mounted Eye Tracker

21. Ⅱ. Theory and the Classification of EGT Technology From View of Theory Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG Limbus-Scalar IR Tracking ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. By placing IR light emitting diodes and photo-transistors, respectively, above and below the eye. the resulting voltage difference is proportional to the angular deviation of the eye. Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement

22. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement The Limbus is the boundary between the white sclera and the dark iris of the eye. By placing IR light emitting diodes and photo-transistors, respectively, above and below the eye. the resulting voltage difference is proportional to the angular deviation of the eye. 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼 球运动的位置信息 The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

23. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼 球运动的位置信息 By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

24. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼球 运动的位置信息 The Limbus is the boundary between the white sclera and the dark iris of the eye. By placing IR light emitting diodes and photo-transistors, respectively, above and below the eye. the resulting voltage difference is proportional to the angular deviation of the eye. Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

25. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼 球运动的位置信息 Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

26. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼 球运动的位置信息 Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

27. Purkinje Image The Purkinje images are reflections created at different layers of the eye structure. Eye gaze can be calculated from these relative positions of these reflections EOG ANN Contact Lens Pupil-Corneal reflection By placing electrodes around the eye, it is possible to measure small differences in the skin potential corresponding to eye movement. The Limbus is the boundary between the white sclera and the dark iris of the eye. This boundary can easily be optically detected and tracked Training images are taken when the user is looking at a specific Calibration markers. Use ANN to decide the eye gaze Use a small coil embedded into a contact lens that is tightly fit over the sclera. The user’s gaze is estimated from measuring the voltage induced in the search coil by an external electro-magnetic field. The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement 将两对氯化银皮肤表面电极分别置于眼睛左右、上下两侧, 就能引起眼球变化方向上的微弱电信号, 经放大后得到眼 球运动的位置信息 The IR source can generate a glint on corneal and divide pupil from iris, the difference between can represent the eye gaze movement Limbus-Scalar IR Tracking Ⅱ. Theory and the Classification of EGT Technology From View of Theory

28. Ⅱ. Theory and the Classification of EGT Technology EGC TechnologyAccuracyFeatures Purkinje Image 0.017 0 High accuracy, but the light is hard to control and can only be used in Lab EOG 1.50-2° low robustness, low accuracy, high intrusiveness Limbus Tracking V 1 0 -7 0 H 0.5 0 -7 0 Horizontal accuracy is better than Vertical, but both are low ANN 1.3-1.8° No need of calibration,low accuracy, Contact Lens 0.08 0 high accuracy, high intrusiveness Pupil Corneal Reflection 1° The best one till now

29. Ⅱ. Theory and the Classification of EGT Technology Feature of Eye Movement  从系统应 用角度  view of humanity

30. Early stage : Direct Observation,Mechanical Method Initial Methods, not used any more for high intrusiveness and poor accuracy Development ： EOG 、 Electromagnetic Oculography Although have improved a lot and widely used, these method are disappearing because of the intrusiveness Advanced ： Optical Method ： Because of its’ high accuracy and low intrusiveness, Optical Method have made rapid progress in recent years. 1. The Purkinje images are reflections created at different layers of the eye structure. and the eye gaze can be calculated from these relative positions of these reflections 2. Photo-Oculography : it measures the eye movement during it's translation/rotation. with the IR light source, shape of the pupil,Limbus or corneal reflection is detected 3. Limbus-Scalar IR Method: They place IR light emitting diodes and IR light sensitive photo- transistors, respectively, above and below the eye. Several such IR pairs can be mounted on goggles or helmets, a photo-transistor transforms the reflected IR light into a voltage. the resulting voltage difference is proportional to the angular deviation of the eye. 4. Pupil-Corneal Reflection: The IR source can generate a glint on corneal and divide pupil from iris, the camera can extract the pupil which represent the eye gaze, on the other hand the corneal reflection represent the head motion, as a result, the difference between them represents the real eye gaze movement. 。 Ⅱ. Theory and the Classification of EGT Technology Development

31. Ⅱ. Theory and the Classification of EGT Technology Feature of Remote Eye Gaze Tracker Robustness  Light Source  Eyelash, Eyelids and Camera Position  System Error  Eye station (dry or wet)  head motion Lower accuracy than Head Mounted Eye Tracker  View of appearance

32. Ⅲ A Practical Eye Gaze Tracking System

33. Ⅲ A Practical Eye Gaze Tracking System Framework of EGT System Hardware ： a Pair of Cameras eye camera scene camera eye camera is for acquisition of pupil corneal reflection image, scene camera is for: 1 mapping from the eye image coordinate to scene image coordinate ;2 Showing the combining result of POR and scene in same image ：

34. Ⅲ A Practical Eye Gaze Tracking System appearance of EGT System

35. Ⅲ Practical Eye Gaze Tracking System Theory of a Head Mounted Eye Tracker

36.  When IR source is placed near the optical axis of the camera bright pupil as can be seen ;while IR is placed off the optical axis, a dark pupil can be seen. By Thresholding, a robust pupil contour can be extracted. Bright Pupil Dark Pupil Difference Image Ⅲ Practical Eye Gaze Tracking System Bright Pupil and Dark Pupil

37. The IR source can generate a glint on corneal and divide pupil from iris, the camera can extract the pupil which represent the eye gaze, on the other hand the corneal reflection represent the head motion, as a result, the difference between them represents the real eye gaze movement. Bright Pupil Dark Pupil Corneal Reflection

38. Ⅲ Practical Eye Gaze Tracking System

41. HOW FAR YOU CAN FLY Part IV :Applications 2015-8-13 EIE426-AICV 41

42. Applications  Human Computer Interaction (HCI) —— efficiency, humanity  Intelligent Control —— EGT and Weapon Control  Human Movement Study —— Typing, physical training  Psychology —— Antinational Neuroscience,  Visual attention & Driving —— Aviation, navigation, driving, traffic accidents inspection  Scene and Image Perception —— Web, AD, Designing, Scene 2015-8-13 EIE426-AICV 42

52. 2015-8-13 EIE426-AICV 52 Most Recent Application