09-09-2020, 05:56 AM
After calibration it is important to check the grid of +'s formed by the calibration fixations. If calibration is done correctly, then all of the fixations should form a nice well-shaped grid. For example, all points from a 9-point calibration should form three parallel horizontal or close-to-horizontal lines and three parallel vertical or close-to-vertical lines.
A tilted or slightly trapezoidal pattern in the calibration grid is not typically a problem. However, significant skew or the presence of outliers in the calibration points are generally an indication that the geometry between the camera, screen and participant is not optimal. If one or both the top corners are too far out (see example below), then the monitor may be too close, or too high. In some cases it may be necessary to adjust the angle of the camera to record participant, e.g., those who are particularly tall. Particularly in Remote mode, a tilted or improperly placed camera can mean the head tracking sticker could be more easily lost if the participant tilts their head, and if the camera is too low it may be difficult to track the top corners of the screen for some participants. The camera should be raised as high as possible without blocking the bottom of the Display monitor from the participant's point of view. If using the EyeLink 1000 Plus, the height of the camera can be adjust on the Desktop mount itself; if using the EyeLink 1000, the Desktop mount can be raised on a stand or even a stack of books.
Please review the Quick Start guide for directions on correct camera, Display monitor, and participant positioning: The relevant Setup Video Tutorials may also be useful:
A tilted or slightly trapezoidal pattern in the calibration grid is not typically a problem. However, significant skew or the presence of outliers in the calibration points are generally an indication that the geometry between the camera, screen and participant is not optimal. If one or both the top corners are too far out (see example below), then the monitor may be too close, or too high. In some cases it may be necessary to adjust the angle of the camera to record participant, e.g., those who are particularly tall. Particularly in Remote mode, a tilted or improperly placed camera can mean the head tracking sticker could be more easily lost if the participant tilts their head, and if the camera is too low it may be difficult to track the top corners of the screen for some participants. The camera should be raised as high as possible without blocking the bottom of the Display monitor from the participant's point of view. If using the EyeLink 1000 Plus, the height of the camera can be adjust on the Desktop mount itself; if using the EyeLink 1000, the Desktop mount can be raised on a stand or even a stack of books.
Please review the Quick Start guide for directions on correct camera, Display monitor, and participant positioning: The relevant Setup Video Tutorials may also be useful: