1. Do-It-Yourself Eye Tracker: Impact of the Viewing Angle on the
West Pomeranian University of Technology in Szczecin Faculty of Computer Science
Do-It-Yourself Eye Tracker: Impact of the Viewing Angle on the
Eye Tracking Accuracy
Michał Kowalik
Master's thesis supervised by: Adam Nowosielski
Article supervised by: Radosław Mantiuk

2. Purposes Building low cost Do-It-Yourself (DIY) eye tracking system
Determining accuracy of constructed eye tracking system
Finding relation between the accuracy of eye tracker and an observer view angle
Michał Kowalik

3. How do eye trackers work?+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Eye tracking devices determine the position of the eye and compute position of a gaze point
Michał Kowalik

4. Main idea of eye tracking systems
The main idea of eye tracking systems is estimating the point of gaze using position of the eye in grabbed image.
Image source: Riad I. Hammoud, Passive Eye Monitoring Algorithms, Applications and Experiments. Springer 2008.
Michał Kowalik

5. Dark and bright pupil effect
Different positions of IR lamps determine two appearance types of human pupil. +
Human eye in infrared light - dark pupil on the left and bright pupil on the right.
Michał Kowalik

6. Eye tracker accuracy
The accuracy is determined by distance between target and estimated gaze point in degrees.
It is measured in degrees of visual angle.
Point of regard
Target point +
Visual angle
Michał Kowalik

7. Error factors affecting accuracy of eye tracker
A main error affecting the accuracy of the gaze point estimation is the head movement. Others problems: extreme position of eyeball and changing illuminaton.
A) Good position of eye B) extreme position of eye
Michał Kowalik

8. Do-it-yourself Eye Tracker Schema
Michał Kowalik

9. Off-the-shelf components
Total cost about 30 €
Elements of eye gaze tracking glasses: 1) heat shrinkable tubin, 2) negative film, 3) carbon resistor, 4) mounting strips, 5) aluminum wire, 6) IR LEDs, 7) Webcam LifeCam VX-1000, 8) safety glasses
Michał Kowalik

10. Eye tracking glasses (1)
Webcam lens with visible light filter
Preparing IR filter
Creating IR LEDs circuit
Capture module
Michał Kowalik

11. Eye tracking glasses (2)
Michał Kowalik

12. ITU Gaze Tracker Application
An open-source gaze tracking application developed by the Gaze Group at the 
IT University of Copenhagen ( )
Michał Kowalik

13. Perception study Participants: 10 users with an age from 21 to 56
Purpose of the test was to calculate accuracy of our eye tracking system.
Participants: 10 users with an age from 21 to 56
Tracking the target points that were displayed on the screen one by one
Test for 70 cm, 50 cm and 30 cm distances
Calculation of accuracy
Tests station
Michał Kowalik

14. Target points – coordinates in pixels20
646
1273
1900 20
366
713
1060
Michał Kowalik

15. Horizontal (err deg / std)
Results – distance 70cm
Horizontal (err deg / std)
0.34 / 0.49
Vertical
(err deg / std)
0.45 / 0.58 A B C D E F G H I J K L M N O P
Y screen axis
X screen axis
Michał Kowalik

16. Horizontal (err deg / std)
Results – distance 50cm
Horizontal (err deg / std)
0.59 / 0.75
Vertical
(err deg / std)
0.55 / 0.59 A B C D E F G H I J K L M N O P
Y screen axis
X screen axis
Michał Kowalik

17. Horizontal (err deg / std)
1.77 / 1.71
Vertical
(err deg / std)
1.2 / 1.03
Results – distance 30cm A B C D E F G H I J K L M N O P
Y screen axis
X screen axis
Michał Kowalik

18. Horizontal (err deg / std)
0.34 / 0.49
Vertical
(err deg / std)
0.45 / 0.58
Results – distance 70cm
0.2
0.4
0.6
0.8 1
1.2
1.4
1.6
1.8 2
distance in degrees between target and gaze points A B C D E F G H I J K L M N O P
target points
Michał Kowalik

19. Horizontal (err deg / std)
Results – distance 50cm
Horizontal (err deg / std)
0.59 / 0.75
Vertical
(err deg / std)
0.55 / 0.59
0.5 1
1.5 2
2.5
distance in degrees between target and gaze points A B C D E F G H I J K L M N O P
target points
Michał Kowalik

20. Horizontal (err deg / std)
Results – distance 30cm
Horizontal (err deg / std)
1.77 / 1.71
Vertical
(err deg / std)
1.2 / 1.03 1 2 3 4 5 6 7
distance in degrees between target and gaze points A B C D E F G H I J K L M N O P
target points
Michał Kowalik

21. Conclusions and future work
Precision drops with wider angles of view.
Accuracy of the DIY eye tracker is close to 0.6 degree for standard viewing angles
Implementing validation of DIY
Building low cost head tracking device and integration with the DIY eye tracker.
Michał Kowalik

22. SMI IVIEW X™ HED Vs DIY Eye Tracker
Accuracy: 0,1°
Technique: Monocular, pupil-CR,
dark-pupil tracking
-large cost about ~30 000€
+ included head movements tracking
+ ready to use hardware
Accuracy: 0,6° for 50cm distance
Technique: monocular,
dark-pupil tracking
+low cost about 30€
- without head tracking
- need to create hardware

23. Thank You for Your attention!
West Pomeranian University of Technology in Szczecin Faculty of Computer Science
Do-It-Yourself Eye Tracker: Impact of the Viewing Angle on the
Eye Tracking Accuracy
Thank You for Your attention!