Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 May 16;17(1):10.16910/jemr.17.1.5.
doi: 10.16910/jemr.17.1.5. eCollection 2024.

Potential of a laser pointer contact lens to improve the reliability of video-based eye-trackers in indoor and outdoor conditions

François-Maël Robert  1 , Marion Otheguy  2 , Vincent Nourrit  2 , Jean-Louis de Bougrenet de la Tocnaye  2
Affiliations

Potential of a laser pointer contact lens to improve the reliability of video-based eye-trackers in indoor and outdoor conditions

François-Maël Robert et al. J Eye Mov Res. .

Abstract

Many video-based eye trackers rely on detecting and tracking ocular features, a task that can be negatively affected by a number of individual or environmental factors. In this context, the aim of this study was to practically evaluate how the use of a scleral contact lens with two integrated nearinfrared lasers (denoted CLP) could improve the tracking robustness in difficult lighting conditions, particularly outdoor ones. We assessed the ability of the CLP (on a model eye) to detect the lasers and to deduce a gaze position with an accuracy better than 1° under four lighting conditions (1 lx, 250 lx, 50 klux and alternating 1lx /250 lx) on an artificial eye. These results were compared to the ability of a commercial eye tracker (Pupil Core) to detect the pupil on human eyes with a confidence score equal to or greater than 0.9. CLP provided good results in all conditions (tracking accuracy and detection rates). In comparison, the Pupil Core performed well in all indoor conditions (99% detection) but failed in outdoor conditions (9.85% detection). In conclusion, the CLP presents strong potential to improve the reliability of video-based eyetrackers in outdoor conditions by providing easy trackable feature.

Keywords: artificial eyes; calibration; contact lenses; eye-tracker; eye-tracking; gaze.

PubMed Disclaimer

Conflict of interest statement

The authors declares that the contents of the article are in agreement with the ethics described in http://biblio.unibe.ch/portale/elibrary/BOP/jemr/ethics.html and that there is no conflict of interest regarding the publication of this paper.

Figures

Figure 1.
Figure 1.
Contact lens with the secondary antenna (1) and the two VCSELs (2). The primary antenna is set in an eyewear worn by the subject. The SCL is here worn during a wearing test by the scleral lens specialist in charge of the design and manufacture of these lenses.
Figure 2.
Figure 2.
Left image: the eyewear, i.e. a 3D printed glasses frame with the primary antenna inside and supporting the Pupil Core cameras. Right image: the detection system with: a) the eyewear with an additional head-strap for improved stability, b) the battery of the Raspberry PI and c) the Raspberry Pi RP2040. This is the fully wearable configuration. When connected to a standard PC, the Raspberry and battery are not needed.
Figure 3.
Figure 3.
Left image: The different model eyes tested. Middle and left images: view of the eye prosthesis and a human eye when using the Pupil Core. The bright spots on the iris correspond to the Pupil Core IR source which is used to illuminate the eye.
Figure 4.
Figure 4.
Left: view of the calibration chart by the world camera in indoor conditions. Right: the model eye on its rotating platform and driving eyewear during outdoor tests.
Figure 5.
Figure 5.
a) Model eye with an embedded laser to visualize the gaze position. b) Cross section of the model eye showing the laser.
Figure 6.
Figure 6.
Image recorded by the Pupil Labs eye camera when using the CLP (left image) or in the classic Pupil Core configuration (right image).
Figure 7.
Figure 7.
Tracking accuracy of the CLP in outdoor conditions using the calibration chart. The red line represents the trajectory (denoted “TC”) the eye has to follow. The blue line represents the gaze position calculated for the CLP.
See this image and copyright information in PMC

References

    1. Blignaut, P. (2014). Mapping the Pupil-Glint Vector to Gaze Coordinates in a Simple Video-Based Eye Tracker. Journal of Eye Movement Research, 7(1). 10.16910/jemr.7.1.4 - DOI
    1. Blignaut, P., & Wium, D. (2013). The effect of mapping function on the accuracy of a video-based eye tracker. Proceedings of the 2013 Conference on Eye Tracking South Africa, 39‑46. 10.1145/2509315.2509321 - DOI
    1. Cerrolaza, J. J., Villanueva, A., & Cabeza, R. (2008). Taxonomic study of polynomial regressions applied to the calibration of video-oculographic systems. Proceedings of the 2008 symposium on Eye tracking research & applications, 259-266. 10.1145/1344471.1344530 - DOI
    1. Choe, K. W., Blake, R., & Lee, S.-H. (2016). Pupil size dynamics during fixation impact the accuracy and precision of video-based gaze estimation. Vision Research, 118, 48–59. 10.1016/j.visres.2014.12.018 - DOI - PubMed
    1. Dierkes, K., Kassner, M., & Bulling, A. (2018). A novel approach to single camera, glint-free 3D eye model fitting including corneal refraction. Proceedings of the 2018 ACM Symposium on Eye Tracking Research & Applications, 1‑9. 10.1145/3204493.3204525 - DOI

LinkOut - more resources