Eye tracking: principles and applications 廖文宏 Wen-Hung Liao 12/10/2009

Outline Eye Tracking Device Application areas State-of-the-art technology Eye 1.0 (wearable) Eye 2.0 (remote) Gaze-based HCI Demo Conclusions

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

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). Eye movements The resulting series of fixations and saccades is called a scanpath.scanpath

Web Design (U. of Manchester) Heat mapGaze plot

Usability Study: Google Search Evaluation

Gaming

Driving Behavior [Andrew T. Duchowski]

Character Input EyeWrite [Andrew T. Duchowski]

Media Research The Poynter Institute : Published first eye track study in More results published in 2000, 2004 and Eyetrack ’07: asp?id= asp?id=105035

Research Communities ACM SIG/CHI Eye Tracking Research and Applications (ETRA) Symposium: COGAIN: Communication by Gaze Interaction References:

State-of-the-art Eye tracking Technology Hi-Speed (SMI iView X™ Hi-Speed) Head-Mounted System Remote tracking Integrated with LCD monitor

Mobile Eye Tracker NCCUCS eye camera scene camera

Key Objectives Low-cost (NTD 10,000 vs. 1,000,000) Mobility Easily customized for specific applications On-line processing Sampling rate? Accuracy?

System Architecture Eye image Preprocessing Pupil detection Gaze point projection Scene image Calibration 9 pairs of points Calibration process

Pupil Detection (I): extracting feature points

Pupil Detection (II): Ellipse fitting using RANSAC

Pupil Detection (III): checking fitness measure Ellipse model: Number of bright vs. dark points inside and out the perimeter

Results

HCI Application: Eye Scrolling

HCI Application: Eye Gaming

HCI Application: Eye Typing

Mobile Eye Tracker NCCUCS Improve the pupil detection algorithm to alleviate corneal reflection problem. Enhance the accuracy by compensating for head movement. Construct and test a remote eye tracker. More HCI applications using the remote eye tracker. Use the eye tracking device to assist mobile user interface design.

Improved Pupil Detection

Allowing Head Movement

Remote Eye Tracker

Experimental Results (Wearable) Calibration point Original error Compensate for head movement (error/standard deviation) (12.7) (10.94) (9.57) (21.19) (7.79) (10.96) (8.01) (6.78) (9.66) 1 cm = 38 Pixels

Accuracy (Wearable)

Experimental Results (Remote) Calibration pointOriginal error Compensate for head movement (error/standard deviation) (24.6) (22.82) (21.49) (30.94) (16.71) (21.83) (41.57) (31.71) (24.41)

Accuracy (Remote Eye Tracker)

Demo: Web Browsing

Demo: Photo Viewing

Demo: Interactive Story Telling

Demo: Tic-Tac-Toe

Summary Eye tracking device Low cost (<$10,000 NTD) Head-mounted with mobile functionality Remote eye tracking Allow slight head movements Accuracy: suitable for some HCI applications, image viewing tasks, not high enough for reading HCI applications

More materials

Gaze Path Analysis Recursive intersection Find the similarity between two scan paths Order of scanning is irrelevant Suitable for processing fixation data Modified dynamic time warping Order of scanning is taken into account Can handle both fixation and saccade data

Recursive Intersection Path 2 Path 1

Recursive Intersection: Example

Dynamic Time Warping (DTW)

Modified DTW (MDTW) X-axis Y-axis time

MDTW Result