Reply To: Pupil Foreshortening Error

[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.