Environment - jackspaceBerkeley/pupil GitHub Wiki

For any eye tracker the physical enviroment plays a big role in tracking performance. Here is some information.

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Lighting conditions

Pupil uses a method called "Dark Pupil Infrared Tracking." This makes it easier to detect and segment the pupil in the infrared (IR) spectrum. Using this method, the pupil appears as a dark spot and the iris as much brighter, regardless of its color in the visible spectrum.

Observing the the eye in the visible light spectrum you (and a camera) will see all kinds of environmental reflections on the cornea. These reflections will have even greater contrast than the border between the pupil and iris! Attempts to find the pupil center using edge detection usually fails in the visible light spectrum because the surround gives better edges than the pupil.