Pupil Foreshortening Error

[Michael Wimmer]

Hi Tobii!

I am using a HP Omnicept G2 Reverb and record pupil size data during a video game. Is the algorithm for pupil size calculation considering gaze angle-dependencies in the pupil size? If no or not completely, is there a gaze range in x and y direcion you can recommend for a save use of the metric?

[Grant [Tobii]]

Hi @miwi, we cover in some detail the image-based algorithm used to determine pupil size which is independent of gaze angle @

https://www.tobiipro.com/learn-and-support/learn/eye-tracking-essentials/is-pupil-size-calculations-possible-with-tobii-eye-trackers/

So there is no gaze range as such, but as the document indicates, it is better use % of pupil size difference rather than any absolute value.

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