Re-Taking Calibration Points; Re-Starting The Calibration Procedure; Terminating The Calibration Procedure; Accepting Calibrations - LCT Eyegaze Edge User Manual

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operation, the user may not be able to accurately target very small keys if the system's calibration is

"loose." The Standard calibration is always preferable, and will provide the user with the highest

level of accurate Eyegaze key activation. If the user is able to do a standard calibration it should be

used.

1.4.7 Re-taking Calibration Points

If the user does not get a sufficiently accurate calibration, i.e., if the average error is more than .25

inches in the Standard calibration or .66 inches in the Simple calibration, the calibration program

assumes it did not get good readings on one or more of the calibration points. It will automatically

repeat the data collection for the worst-case points. The Eyegaze Edge indicates a point it will retake by

displaying the icon at that point. The user should prepare to look at that icon. After the calibration point

is re-taken, the program readjusts the calibration parameters and re-computes the calibration accuracy.

If a calibration point re-take is less accurate, the system ignores the re-take, and keeps the previous

calibration. It first displays the results of the re-take then the prior better performance is again

displayed. If the accuracy is still not good enough, it will again display a purple, then yellow, circle for

the user to look at. If the accuracy improves enough during one the re-takes, the calibration procedure

is completed, and the Edge automatically displays the Main Menu.

If the calibration procedure is not going well, it can be restarted at any time by pressing the "Re-

calibrate" key (F1) on the manual keyboard.

The calibration procedure can be terminated at anytime by pressing the Escape key (Esc) on the

manual keyboard. If the calibration procedure is terminated with an Escape, the Eyegaze Edge

completely ignores any results from that calibration session and returns to the calibration results that

existed prior to that session. Escaping from the calibration procedure is useful any time a good

calibration already exists, and the user does not wish to recalibrate.

If the user has limited eye control, which hinders his calibration accuracy, you may press the "Accept

Calibration" key (F3) on the manual keyboard to instruct the Edge to accept a calibration of great than

.25 inches. You may accept a calibration at any time after the user completes the original calibration

points, i.e., either during the re-takes or while the screen again displays its message to begin

calibration. It is important to pay attention to the calibration accuracy number being accepted (displayed

in the upper left corner of the screen.)

As a rule of thumb, doubling that calibration number will give you an indication of the size of the keys

the user will be able to accurately target. For example, a calibration of .75 inches means the user will

be able to activate keys 1.5 square inches or larger. In some cases, a user may be able to calibrate

more accurately using the 5-point calibration instead of the 9-point. You may want to try both calibration

procedures to see which gets better results. It is also wise to try calibration on the opposite eye to see if

the results are better.

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