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6.5 Calibration
When you are done configuring your eye tracker, you should run a calibration to test to
see if the eye tracker is mapping the gaze points correctly to your display.
How to test your eye tracking setup in Tobii Pro Eye Tracker Manager:
1. Make sure the eye tracker is attached to the screen bezel and connected to your
computer. Open Tobii Pro Eye Tracker Manager.
2. By now you should have also tested your setup as described in
Display setup in
Tobii Pro Eye Tracker Manager.
3. Select Calibrate in Tobii Pro Eye Tracker Manager and follow the on-screen
instructions.
4. Evaluate your calibration results. Large systematic errors i.e., a large distance
between the average gaze point and the target gaze point may be indicative of a
configuration error. No calibration feedback data on the targets located on the top
of the screen may indicate that there is a mismatch between the screen size and
eye tracker configuration. Select Recalibrate to improve an unsuccessful
calibration (e.g., recalibrate points with missing data). Select Use Calibration
when you are satisfied with the calibration.
You can toggle on and off Gaze Visualization in the upper left corner of the
Calibration Results window (or on the Overview tab). This can be used to
confirm the participant’s calibration results.
6.5.1 What calibration does
The human eye shows a natural individual variation in its shape and geometry. For
example, the exact location of the fovea, the area responsible for the part of the visual
field that we perceive in focus and full color, varies from individual to individual. Tobii eye
trackers use an individual calibration procedure to optimize their gaze estimation
algorithms (i.e., the 3D eye model) and account for this variation. The end result of this
optimization is a fully customized and more accurate gaze point calculation. Additionally,
some Tobii eye trackers use the calibration procedure to select the detection mode (e.g.
dark or bright pupil tracking) that provides the most accurate data.
You can do basic calibration in Tobii Pro Tobii Pro Eye Tracker Manager. There is more
functionality, including calibration validation, in Tobii Pro Lab.
For more information, read the articles on eye tracker calibration and on
how to calibrate
and validate in Tobii Pro Lab.
6.6 Detach the eye tracker
To temporarily remove the eye tracker, gently pull it away from the magnetic mounting
bracket and leave the bracket in place.
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