Tobii X1 Light Eye Tracker, Руководство пользователя

Страница: 41 / 52

Tobii X1 Light User Manual
41
7 Appendices
7.1 Appendix A: Eye tracking specifications
The characteristics of an eye tracker can be described in terms of gaze accuracy and gaze
precision. Accuracy describes the angular average distance from the actual gaze point
to the one measured by the eye tracker. Gaze precision describes the spatial variation
between successive samples collected when the subject fixates at a specific point on stimuli.
More information regarding the accuracy and precision measurements can be found in
the document Accuracy and precision test method for remote eye trackers, which can be
downloaded from the Tobii website. A glossary can be found in 6.3 Appendix C: Glossary.
Gaze accuracy
Monocular Binocular
At ideal conditions
1)
0.5° 0.5°
At 25° gaze angle 0.4° 0.3°
At 30° gaze angle
0.4° 0.3°
At 1 lux
1.4° 0.9°
At 300 lux 0.5° 0.5°
At 600 lux 0.8° 0.5°
At 1000 lux 0.9° 0.5°
White stimuli background (300 lux) 0.5° 0.5°
1) Accuracy under ideal conditions is measured in the center of the head movement box with the subject fixed in a chinrest.
Data is collected immediately after calibration in a controlled laboratory environment with constant illumination with 9 stimuli
points at gaze angles of
≤
18º.
Gaze precision
Monocular Binocular
Without filter
0.27° 0.20°
With Stampe filter 2
1)
0.08° 0.06°
1)
Stampe (Behavior Research Methods, Instruments & Computers, 1993, 25 (2), pp.137-142) describes a noise reduction
filter commonly used for eye tracking data. In these measurements, the Stampe stage 2 algorithm has been applied.
Chapter 7 Appendices