Tobii X2-30, User Manual

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Appendix B Recommended Display Sizes
The eye tracker can only do accurate eye tracking of a person ’ s eyes if the visual angle, as seen from the person ’ s eyes, does not
exceed 36° for the Compact Edition, between the center of the eye tracker and any point on what the person is looking at. This
is valid as long as the person stays within the area in front of the eye tracker defined as the
“ freedom of head movement ” , which
is roughly between 40-90 cm for the Tobii X2 Eye Tracker from the center of the eye tracker when seen from the side (read
more about this in
6 Positioning, page 19.
This means that depending on the position of the eye tracker in relation to the display, it can track different sizes of displays. If
the display is positioned further away from the user, a larger area can be tracked. However, small objects shown on the display
might be difficult to see for the user at a greater distance.
Another aspect to consider is the aspect ratio of the display. Since the optimally tracked area is a half circle, the eye tracker can
track displays with a large width to height ratio better than displays where this ratio is small:
The display sizes below have been calculated to be within 36° gaze angle and is therefore suitable for use with the Tobii X2 Eye
Tracker. It might be possible for some users to use larger displays than the ones given below, but that will be at the user
’ s own
risk of not being able to collect eye tracking data in the top corners of the display.
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T Toob biiii X X2 2 E Eyyee T Trraacckkeerr — — C Coom mp paacctt E Ed diittiioonn
16:9 25 ʺ
16:10 24 ʺ
4:3 22 ʺ
5:4 22 ʺ
The display sizes above are based on tests on participants without vision aids such as lenses or glasses in normal
office lighting without any interfering light sources such as windows or near infrared light-emitting lamps. For
participants with glasses, lenses or other characteristics that might interfere with trackability, for example, droopy
eyelids, extensive use of mascara or environment with interfering light sources, the trackability in the top corners of the
display might be lower than for the conditions tested here.
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Appendix B Recommended Display Sizes Tobii X2-30 Eye Tracker User ’ s manual v.1.0.3 - en-US