EyeLink II Scene Camera User Manual
©
2004-2007 SR Research Ltd.
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The “Monitor Size” values measure the distance of the visible part of the display
screen edges relative to the center of the screen in millimeters (corresponding to
“screen_phys_coords” command). Enter a negative value for the left edge and
bottom edge distances. Click “Detect” button will let the software automatically
detect the size of the monitor. The “Marker Positions” values are determined by
the physical position of LED markers (corresponding to “marker_phys_coords”
command). The X/Y values in the table refer to the horizontal and vertical
distances in millimeters relative to the center of the screen. Enter a negative
value if the marker is to the left of the center of screen or below the center of
the screen.
To apply changes in the physical coordinate settings, press the “Send” button.
The modified settings will be used for the current session. Always redo a
calibration if the physical setup values are updated. Enable the “Automatically
send physical and marker cords for future sessions” option if the modified
settings should persist over future sessions.
4.6 Depth Correction Mode
The depth correction mode ( ) is used to correct for depth parallax in the scene
camera overlay and
must
be performed prior to each recording session.
In a
scene camera recording, if “cyclopean gaze cursor” option is enabled, the “ball”
of the cursor is positioned at the average X and Y gaze position of the two eyes.
When a participant is fixating on a target at an uncalibrated plane, the ball of
the cursor may be drawn at a different position from where the participant
intends to look at. This error is caused by the difference in the viewing angles
between the scene camera and the eyes (i.e., parallax error). Therefore, a depth
correction following calibration is critical for any experiment involving viewing
targets at different viewing depths.
