Dynamic camera rotation calibration

An arrangement for calibrating an eye tracking camera of an eye tracking system, the arrangement comprising:

• the eye tracking system, having at least one eye tracking camera and a plurality of illuminators;
• and
• a calibration processor, being arranged to:
• a) capture an eye image of the user, wherein the eye image contains a plurality of glints created by a plurality of illuminators in the eye tracking system,
• b) detect glints in the eye image,
• c) project illuminator positions onto the eye image to determine expected glint positions,
• d) determine an angular offset between the expected the glint positions and detected glint positions for corresponding pairs of expected and detected glint positions,
• e) determine the angular correction for the eye tracking camera using the determined angular offset angle, and
• f) apply the angular correction for the eye tracking camera to the eye tracker camera model.

A non-transitory computer-readable storage medium storing instructions which, when executed by an eye tracking system cause the system to carry out the steps of:

• a) capturing an eye image of the user using an eye tracking camera, wherein the eye image contains a plurality of glints created by a plurality of illuminators in the eye tracking system,
• b) detecting glints in the eye image,
• c) projecting illuminator positions onto the eye image to determine expected glint positions,
• d) determining an angular offset between the expected the glint positions and detected glint positions for corresponding pairs of expected and detected glint positions,
• e) determining the angular correction for the eye tracking camera using the determined angular offset angle, and
• f) applying the angular correction for the eye tracking camera to the eye tracker camera model.