Focus adjustment method for a virtual reality headset

A method comprising:

• determining, using at least one image capturing element inside a head-mounted display (HMD), an eye position for each eye of a user, the HMD including an optics block configured to focus light from a display presenting a virtual scene to an exit pupil and a varifocal element configured to change a focal length of the optics block based on a viewing location within the virtual scene of the user;
• determining a three-dimensional (3D) gaze point of the user based at least in part on the eye position determined for each eye, the determined three-dimensional gaze point identifying the viewing location within the virtual scene;
• estimating a vergence depth for the viewing location of the user based on 3D gaze point, the estimated vergence depth corresponding to an object of focus for the user;
• comparing the estimated vergence depth to a depth associated with the viewing location identified by scene geometry data for the object within the virtual scene;
• replacing the estimated vergence depth with the depth associated with the viewing location based on a difference between the estimated vergence depth and the depth of the viewing location being greater than a threshold;
• adjusting the focal length of the optics block for the virtual scene based on the depth of the viewing location identified by the scene geometry data using the varifocal element to provide accommodation for the object of focus;
• and
• displaying, the virtual scene on the display of the HMD.

A non-transitory computer-readable storage medium storing instructions that, when executed by at least one processor, cause the processor to:

• capture, using a camera of ahead-mounted display (HMD), image information corresponding to an eye position for each eye of a user, the HMD including an optics block configured to focus light from a display presenting a virtual scene to an exit pupil and a varifocal element configured to change a focal length of the optics block based on a viewing location of the user within the virtual scene;
• determine gaze lines of the user based at least in part on each eye position, the determined gaze lines identifying the viewing location within the virtual scene;
• estimate a vergence depth for the viewing location of the user based on an estimated intersection of the gaze lines;
• compare the estimated vergence depth to a depth associated with the viewing location identified by the scene geometry data;
• replace the estimated vergence depth with the depth associated with the viewing location based on a difference between the estimated vergence depth and the depth of the viewing location being greater than a threshold;
• adjust the focal length of the optics block for a frame of the virtual scene using the varifocal element based on the depth associated with the viewing location identified by the scene geometry data to provide accommodation for the plane of focus;
• and
• display the virtual scene on the display of the HMD.