APPENDIX AVI212 Manual do Utilizador descarregar pdf (Página 198)

BeGaze 2.3

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monitor displaying 1280 horizontal pixels should have a width of 338 mm

(1280 px / 96 dpi * 25,4 mm per inch). Note also that other displays such

as a video beamer emitting camcorder material typically use a different

dpi resolution for horizontal and vertical display.

Distance monitor-head: If you change the Phys. stimulus dimensions

settings, you need to adapt the approximate distance between the

displaying monitor and the subjects head accordingly. Note that during

calibration the individual relation between the gaze tracking system and

the subject is established. The calibration outcome is not changed nor

invalidated with this setting.

Overwriting and changing the geometry settings requires BeGaze

2.3 to re-calculate the gaze tracking data in order to adapt to the

new settings. For longer experiments, the recalculation may require

some time with the progress indicated by a status dialog.

7.3 Low Speed Event Detection

In the Low Speed Event Detection method, Fixation is selected as primary

event. The Built-In Detector will first search for fixation events, using a

dispersion based algorithm, after which saccade events are computed

and derived from the primary fixation events.

Blink Detection

A blink can be regarded as a special case of a fixation, where the

horizontal and vertical gaze position equals 0. If this is the case, we

create a blink event. However, the duration of the blink event is expanded

in order to include the transition period between valid gaze data and the

blink.

Fixation Detection

The Minimum Fixation Duration defines the minimum time window in

which the gaze data is analyzed. Fixations smaller than the time window

will not be caught.

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