CSE Thu 10/22. Nadir Weibel

Transcription

1 CSE Thu 10/22 Nadir Weibel

2 Today Admin Teams : status? Web Site on Github (due: Sunday 11:59pm) Evening meetings: presence Mini Quiz Eye-Tracking

3 Mini Quiz on Week 3-4

4 Eye-Tracking Credits: Wen-Hung Liao, Antti Aaltonen, Andrew Duchowsky, Sean Burke, Pavan Kumar, Sneha Venkatesh Yelimeli and Brian Anderson

5 Eye Tracking Device An eye tracker is a device for measuring eye positions and eye movements. The most popular variant uses video images from which the eye position is extracted. Input source: visible spectrum vs. infrared

6 Physiology of Eye Cornea is a transparent structure that covers the iris and pupil; a part of the focusing system of an eye. Pupil is the adjustable opening at the center of the iris that allows varying amounts of light to enter the eye. Lens helps to focus light on the retina. Retina includes rods (94%), which are sensitive to light and cones (6%) that capture colors. Cones are concentrated in the centre of the retina - the fovea

7 Eye Movements Eyes move all the time (even during sleep) Several different movement types, such as Pursuit Tremor Rotation Drift But the most interesting types are Fixation Saccade

8 Fixation Eye is a (relatively) still and fixated to the certain point. E.g. reading a single word. All the information from the scene is (mainly) acquired during fixation. Duration varies from ms, typically ms. Typical fixation frequency is < 3 Hz Interspersed with saccades...

9 Saccade Jumps which connect fixations Very rapid -- duration is typically only ms Very fast (up to 600 o /s) and therefore the vision system is suppressed during the movement Ballistic; the end point of saccade cannot be changed during the movement Saccades are used to move the fixation point If larger than 30 degree movement is required, head moves along with eyes

10 Eye Movements Eye movements are typically divided into fixations (when the eye gaze pauses in a certain position) and saccades (when it moves to another position).

11 Eye Tracking Methods Electronic methods Mechanical methods Video-based methods Single point Two point

12 Eye Tracking Techniques Electro-OculoGraphy (EOG) Scleral Contact Lens / Search Coil Photo/ Video-OculoGraphy (POG) Video-Based Combined Pupil / Corneal Reflection Eye Tracking Methodology - Theory and Practice, Second Edition by Andrew Duchowski

13 Electronic methods For a long time the most used method was to place skin electrodes around the eyes and measure the potential differences in eye Wide range -- poor accuracy Better for relative than absolute eye movements Mainly used in neurological diagnosis

14 Mechanical methods Based on contact lenses with mirror planes + reflecting IRlight coil + magnetic field Very accurate Very uncomfortable for users who are not used to wear lenses Usable only for lab studies

15 Single point videobased methods Tracking one visible feature of the eyeball, e.g.: limbus (bondary of sclera and iris) pupil A video camera observes one of the user's eyes Image processing software analyzes the video image and traces the tracked feature Based on calibration, the system determines where the user is currently looking

16 Two point video-based method: 1 The same idea as in the single point method except now two features of eye are tracked typically corneal reflection pupil Uses IR light (invisible to human eye) to produce corneal reflection cause bright or dark pupil, which helps the system to recognize pupil from video image Bright pu Corneal

17 Two point video-based methods: 2 The optics of the system can be mounted on head floor/table If optics are floor/table mounted, the system is not in contact with the user Generally head movements are not restricted and they can be separated from eye movements, but... With floor/table mounted optics the system has to track the user s head in order to keep the eye in the field of view of camera, which limits the head movements.

18 Some terms Accuracy The expected difference in degrees of visual angle between true eye position and mean computed eye position during a fixation. Because of the vision system and physiology of eye the accuracy is usually O. Spatial Resolution The smallest change in eye position that can be measured. Temporal Resolution (sampling rate) Number of recorded eye positions per second.

19 Eye Tracking Calibration Calibration Process Eye Tracking Methodology - Theory and Practice, Second Edition by Andrew Duchowski Systems and methods of eye tracking calibration - US A1

20 State-of-the-art Eye tracking Technology

21 ASL 4000-series (1996) Main components Floor mounted optics Control unit 2 computers (control & subject) Head movements (partially) compensated with tracking mirrors and extended head movement options Temporal resolution 50 Hz Spatial resolution 0.5O Tracks only one eye Poor analysing software and no API

22 SMI EyeLink (1999) Contains Head mounted optics 2 computers (control & subject) Temporal resolution 250 Hz Spatial resolution <0.01O Tracks both eyes Reasonable analysis software WIN API s for Microsoft Visual C++

23 Present Technology Tabletop User must be semi-stationary Approx USD 30,000 No API for development Tabletop Wearables Google Glass (?) Tobii, SMI Wearables

24 Smart Phone Samsung Smart Stay Scrolls when viewing edge of screen Pauses when looking away Uses front-facing camera Amazon Fire Phone Dynamic Perspective Eye/Head Tracking

25 Eyetribe Eye Tracker Features Camera, multiple infrared LEDs Band-pass filter Operating Range: 45-75cm USB 3.0 Superspeed Other Eye Trackers API/ SDK: C++, C#, Java Cost: $99

26 Applications

27 Overview Computer Science Cognitive Science Psychology Neuroscience

28 Usability Study

29 Driving Behavior [Andrew T. Duchowski]

30 Gaming

31 CS - Selective Systems Eye tracker as input device o o Explicit - eg. eye typing Implicit - eg. MAGIC pointing

32 Character Input EyeWrite [Andrew T. Duchowski]

33 CS - Gaze Contingent Display Real time display manipulation to match eye gaze o o o Screen based Model based Attentive UIs

34 Psychology Reading patterns Word fixation and scanning Spritz - Full Product o Reduce need for scanning

35 Assistive Technology: LIS

36 Next Steps Readings to discuss on Tuesday A. Duchowski, "A breadth-first survey of eye-tracking applications." Roda, Claudia, and Julie Thomas. "Attention aware systems: Theories, applications, and research agenda. Optional: Zhai, Shumin. "What's in the eyes for attentive input."

37 Next Steps Submit your reading-summary and annotations by Tue 2pm Read/Annotate all papers Team web page on Github by Sunday 11.59pm Next Week: Smart homes and Smart Buildings

38 Thanks