Hybrid motion stabilisation for augmented reality displays

An augmented reality system comprising:

• a tracker;
• a display;
• an optical combiner arranged on an optical path of the display;
• and
• at least one processor configured to:
• determine a relative position of a given eye of at least one user with respect to the optical combiner, using the tracker;
• maintain a world-locked rendering of a graphical element based on a spatial relationship between the given eye and a real-world reference object;
• detect, over a predefined time period, whether the relative position of the given eye changes by more than a predefined threshold at least a predefined number of times;
• and
• when it is detected that the relative position of the given eye changes by more than the predefined threshold at least the predefined number of times over the predefined time period, then for a subsequent time period;
• switch between the world-locked rendering and a visual stabilised rendering wherein the at least one processor is configured to:
• update a three-dimensional (3D) view frustum corresponding to the given eye, in response to changes in the relative position of the given eye with respect to the optical combiner;
• maintain a spatial anchor at a predefined position within the 3D view frustum;
• determine corresponding positions for a graphical element in images to be presented to the given eye, based on the predefined position of the spatial anchor within the 3D view frustum;
• and
• generate the images for presenting the graphical element to the given eye, positioning the graphical element at the corresponding positions.