Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

The amplitude of small eye movements can be accurately estimated with video-based eye trackers

Nyström, Marcus LU orcid ; Niehorster, Diederick C. LU orcid ; Andersson, Richard LU ; Hessels, Roy S. and Hooge, Ignace T. C. LU (2023) In Behavior Research Methods 55(2). p.657-669
Abstract
Estimating the gaze direction with a digital video-based pupil and corneal reflection (P-CR) eye tracker is challenging partly since a video camera is limited in terms of spatial and temporal resolution, and because the captured eye images contain noise. Through computer simulation, we evaluated the localization accuracy of pupil-, and CR centers in the eye image for small eye rotations (≪ 1 deg). Results highlight how inaccuracies in center localization are related to 1) how many pixels the pupil and CR span in the eye camera image, 2) the method to compute the center of the pupil and CRs, and 3) the level of image noise. Our results provide a possible explanation to why the amplitude of small saccades may not be accurately estimated by... (More)
Estimating the gaze direction with a digital video-based pupil and corneal reflection (P-CR) eye tracker is challenging partly since a video camera is limited in terms of spatial and temporal resolution, and because the captured eye images contain noise. Through computer simulation, we evaluated the localization accuracy of pupil-, and CR centers in the eye image for small eye rotations (≪ 1 deg). Results highlight how inaccuracies in center localization are related to 1) how many pixels the pupil and CR span in the eye camera image, 2) the method to compute the center of the pupil and CRs, and 3) the level of image noise. Our results provide a possible explanation to why the amplitude of small saccades may not be accurately estimated by many currently used video-based eye trackers. We conclude that eye movements with arbitrarily small amplitudes can be accurately estimated using the P-CR eye-tracking principle given that the level of image noise is low and the pupil and CR span enough pixels in the eye camera, or if localization of the CR is based on the intensity values in the eye image instead of a binary representation. (Less)
Please use this url to cite or link to this publication:
author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Microsaccades, EyeLink 1000 plus, Image resolution
in
Behavior Research Methods
volume
55
issue
2
pages
13 pages
publisher
Springer
external identifiers
  • scopus:85128175014
  • pmid:35419703
ISSN
1554-3528
DOI
10.3758/s13428-021-01780-6
language
English
LU publication?
yes
id
3b26588a-ae48-4093-a1cf-90787aa0f132
date added to LUP
2022-04-14 09:54:57
date last changed
2024-01-11 13:39:09
@article{3b26588a-ae48-4093-a1cf-90787aa0f132,
  abstract     = {{Estimating the gaze direction with a digital video-based pupil and corneal reflection (P-CR) eye tracker is challenging partly since a video camera is limited in terms of spatial and temporal resolution, and because the captured eye images contain noise. Through computer simulation, we evaluated the localization accuracy of pupil-, and CR centers in the eye image for small eye rotations (≪ 1 deg). Results highlight how inaccuracies in center localization are related to 1) how many pixels the pupil and CR span in the eye camera image, 2) the method to compute the center of the pupil and CRs, and 3) the level of image noise. Our results provide a possible explanation to why the amplitude of small saccades may not be accurately estimated by many currently used video-based eye trackers. We conclude that eye movements with arbitrarily small amplitudes can be accurately estimated using the P-CR eye-tracking principle given that the level of image noise is low and the pupil and CR span enough pixels in the eye camera, or if localization of the CR is based on the intensity values in the eye image instead of a binary representation.}},
  author       = {{Nyström, Marcus and Niehorster, Diederick C. and Andersson, Richard and Hessels, Roy S. and Hooge, Ignace T. C.}},
  issn         = {{1554-3528}},
  keywords     = {{Microsaccades; EyeLink 1000 plus; Image resolution}},
  language     = {{eng}},
  number       = {{2}},
  pages        = {{657--669}},
  publisher    = {{Springer}},
  series       = {{Behavior Research Methods}},
  title        = {{The amplitude of small eye movements can be accurately estimated with video-based eye trackers}},
  url          = {{http://dx.doi.org/10.3758/s13428-021-01780-6}},
  doi          = {{10.3758/s13428-021-01780-6}},
  volume       = {{55}},
  year         = {{2023}},
}