Implicit gaze and focus distance calibration

A system comprising:

• at least one tracking camera;
• and
• at least one processor configured to:
• capture a plurality of images of a user's face at a plurality of time instants, using the at least one tracking camera;
• process a given image captured at a given time instant, to determine a plurality of tracking parameters comprising:
• a pose of the user's head, positions of eyeballs of the user's eyes, and at least one of:
• relative positions of irises of the user's eyes with respect to boundaries of the eyeballs, relative positions of irises of the user's eyes with respect to corners of the user's eyes, and shapes of the user's eyes;
• estimate uncalibrated gaze vectors of the user's eyes corresponding to the given time instant, based on the plurality of tracking parameters determined from the given image;
• generate a set of uncalibrated gaze vectors of the user's eyes corresponding to the plurality of time instants, by performing said processing and said estimation for each of the plurality of images;
• store at least temporarily the uncalibrated gaze vectors of the set along with corresponding time instants and corresponding pluralities of tracking parameters;
• select, from amongst the set of uncalibrated gaze vectors, a first subset of uncalibrated gaze vectors whose direction matches with a predefined forward axis of vision;
• for the uncalibrated gaze vectors of the first subset, fetch corresponding pluralities of tracking parameters;
• determine a maximum distance between the irises of the user's eyes, based on the corresponding pluralities of tracking parameters fetched for the uncalibrated gaze vectors of the first subset;
• and
• consider the maximum distance as an interpupillary distance of the user for focusing distances greater than a predefined threshold distance.