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Smaller is better: drift in gaze measurements due to pupil dynamics.

Drewes J, Zhu W, Hu Y, Hu X - PLoS ONE (2014)

Bottom Line: Recently, a significant impact of changes in pupil size on gaze position as measured by camera-based eye trackers has been reported.We observed a wide range of drift direction, mostly downward and nasal.We demonstrate two methods to partially compensate the pupil-based shift using separate calibrations in pupil-constricted and pupil-dilated conditions, and evaluate an improved method of compensation based on individual look-up-tables, achieving up to 74% of compensation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision Research, York University, Toronto, Canada; Center for Mind/Brain Sciences, Trento University, Rovereto, Italy.

ABSTRACT
Camera-based eye trackers are the mainstay of eye movement research and countless practical applications of eye tracking. Recently, a significant impact of changes in pupil size on gaze position as measured by camera-based eye trackers has been reported. In an attempt to improve the understanding of the magnitude and population-wise distribution of the pupil-size dependent shift in reported gaze position, we present the first collection of binocular pupil drift measurements recorded from 39 subjects. The pupil-size dependent shift varied greatly between subjects (from 0.3 to 5.2 deg of deviation, mean 2.6 deg), but also between the eyes of individual subjects (0.1 to 3.0 deg difference, mean difference 1.0 deg). We observed a wide range of drift direction, mostly downward and nasal. We demonstrate two methods to partially compensate the pupil-based shift using separate calibrations in pupil-constricted and pupil-dilated conditions, and evaluate an improved method of compensation based on individual look-up-tables, achieving up to 74% of compensation.

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Drift and compensation time course.Top row: background brightness (black dashed) and normalized pupil response across subjects (magenta, mean and s.e.m.). Middle and bottom row: horizontal and vertical aspects of left and right eyes. Black/gray: uncorrected gaze recordings. Blue: 2-Point compensated. Green: 3-Point compensated. Red: LUT compensated. Mean and 1 s.e.m.
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pone-0111197-g004: Drift and compensation time course.Top row: background brightness (black dashed) and normalized pupil response across subjects (magenta, mean and s.e.m.). Middle and bottom row: horizontal and vertical aspects of left and right eyes. Black/gray: uncorrected gaze recordings. Blue: 2-Point compensated. Green: 3-Point compensated. Red: LUT compensated. Mean and 1 s.e.m.

Mentions: Uncompensated drift time courses for left and right eyes averaged across subjects can be seen from Figure 4.


Smaller is better: drift in gaze measurements due to pupil dynamics.

Drewes J, Zhu W, Hu Y, Hu X - PLoS ONE (2014)

Drift and compensation time course.Top row: background brightness (black dashed) and normalized pupil response across subjects (magenta, mean and s.e.m.). Middle and bottom row: horizontal and vertical aspects of left and right eyes. Black/gray: uncorrected gaze recordings. Blue: 2-Point compensated. Green: 3-Point compensated. Red: LUT compensated. Mean and 1 s.e.m.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206464&req=5

pone-0111197-g004: Drift and compensation time course.Top row: background brightness (black dashed) and normalized pupil response across subjects (magenta, mean and s.e.m.). Middle and bottom row: horizontal and vertical aspects of left and right eyes. Black/gray: uncorrected gaze recordings. Blue: 2-Point compensated. Green: 3-Point compensated. Red: LUT compensated. Mean and 1 s.e.m.
Mentions: Uncompensated drift time courses for left and right eyes averaged across subjects can be seen from Figure 4.

Bottom Line: Recently, a significant impact of changes in pupil size on gaze position as measured by camera-based eye trackers has been reported.We observed a wide range of drift direction, mostly downward and nasal.We demonstrate two methods to partially compensate the pupil-based shift using separate calibrations in pupil-constricted and pupil-dilated conditions, and evaluate an improved method of compensation based on individual look-up-tables, achieving up to 74% of compensation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision Research, York University, Toronto, Canada; Center for Mind/Brain Sciences, Trento University, Rovereto, Italy.

ABSTRACT
Camera-based eye trackers are the mainstay of eye movement research and countless practical applications of eye tracking. Recently, a significant impact of changes in pupil size on gaze position as measured by camera-based eye trackers has been reported. In an attempt to improve the understanding of the magnitude and population-wise distribution of the pupil-size dependent shift in reported gaze position, we present the first collection of binocular pupil drift measurements recorded from 39 subjects. The pupil-size dependent shift varied greatly between subjects (from 0.3 to 5.2 deg of deviation, mean 2.6 deg), but also between the eyes of individual subjects (0.1 to 3.0 deg difference, mean difference 1.0 deg). We observed a wide range of drift direction, mostly downward and nasal. We demonstrate two methods to partially compensate the pupil-based shift using separate calibrations in pupil-constricted and pupil-dilated conditions, and evaluate an improved method of compensation based on individual look-up-tables, achieving up to 74% of compensation.

Show MeSH