Display systems and methods for clipping content to increase viewing comfort
Augmented and virtual reality display systems increase viewer comfort by reducing viewer exposure to virtual content that causes undesirable accommodation-vergence mismatches (AVM). The display systems limit displaying content that exceeds an accommodation-vergence mismatch threshold, which may define a volume around the viewer. The volume may be subdivided into two or more zones, including an innermost loss-of-fusion zone (LoF) in which no content is displayed, and one or more outer AVM zones in which the displaying of content may be stopped, or clipped, under certain conditions. For example, content may be clipped if the viewer is verging within an AVM zone and if the content is displayed within the AVM zone for more than a threshold duration. A further possible condition for clipping content is that the user is verging on that content. In addition, the boundaries of the AVM zone and/or the acceptable amount of time that the content is displayed may vary depending upon the type of content being displayed, e.g., whether the content is user-locked content or in-world content.
1. A display system for displaying a virtual object, the display system comprising:
one or more processors; and
one or more computer storage media storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
determining whether the virtual object is located within a loss-of-fusion zone;
determining whether a vergence point of the user's eyes is within the loss-of-fusion zone;
refraining from displaying the virtual object within the loss-of-fusion zone if the virtual object is determined to be located within the loss-of-fusion zone and the vergence point is determined to be located within the loss-of-fusion zone;
determining whether the virtual object is located within an accommodation-vergence mismatch discomfort zone;
determining whether the vergence point of the user is within the accommodation-vergence mismatch discomfort zone; and
limiting displaying of the virtual object to the user if:
the virtual object is located at within the accommodation-vergence mismatch discomfort zone; and
the vergence point of the user is within the accommodation-vergence mismatch discomfort zone.
2. The display system of claim 1 , wherein determining whether the virtual object is located within a loss-of-fusion zone comprises determining whether the virtual object is located at less than a loss-of-fusion threshold distance from a user of the display system.
3. The display system of claim 1 , wherein determining whether a vergence point of the user's eyes is within the loss-of-fusion zone comprises determining whether the vergence point is at a distance, from the user less than a loss-of-fusion threshold distance.
4. The display system of claim 1 , wherein determining whether a vergence point of the user's eyes is within the loss-of-fusion zone comprises determining whether the user is verging at a point corresponding to a vergence angle less than a loss-of-fusion threshold vergence angle, wherein the vergence angle is defined by a first line extending from the point to a first eye of the user and a second line extending from the point to a second eye of the user.
5. The display system of claim 1 , wherein determining whether the virtual object is located within the accommodation-vergence mismatch discomfort zone comprises determining whether the virtual object is located, from the user, at less than an accommodation-vergence mismatch threshold distance of a near accommodation-vergence mismatch discomfort zone.
6. The display system of claim 1 , wherein determining whether the virtual object is located within the accommodation-vergence mismatch discomfort zone comprises determining whether the virtual object is located, from the user, at more than an accommodation-vergence mismatch threshold distance of a far accommodation-vergence mismatch discomfort zone.
7. The display system of claim 1 , wherein determining whether the vergence point of the user is within the accommodation-vergence mismatch discomfort zone comprises determining whether a vergence distance of the user is less than the accommodation-vergence mismatch threshold distance of a near accommodation-vergence mismatch discomfort zone, wherein the vergence distance is a distance of the vergence point from the user.
8. The display system of claim 1 , wherein determining whether the vergence point of the user is within the accommodation-vergence mismatch discomfort zone comprises determining whether a vergence distance of the user is more than the accommodation-vergence mismatch threshold distance of a far accommodation-vergence mismatch discomfort zone, wherein the vergence distance is a distance of the vergence point from the user.
9. The display system of claim 1 , wherein determining whether the vergence point of the user is within the accommodation-vergence mismatch discomfort zone comprises:
determining whether the user is verging on the virtual object.
10. The display system of claim 1 , further comprising redisplaying the virtual object after ceasing to display the virtual content for a cool-down period, where redisplaying the virtual content comprises displaying virtual content at a location outside of the loss-of-fusion zone.
11. The display system of claim 1 , further comprising optics configured to output light forming the virtual object with varying amounts of wavefront divergence.
12. The display system of claim 11 , wherein the optics comprises a stack of waveguides, wherein different ones of the waveguides output light with different amounts of wavefront divergence.
13. The display system of claim 11 , further comprising a projection system for directing light comprising image information into the optics for output to the viewer.
14. The display system of claim 11 , wherein the projection system comprises a light source and a spatial light modulator configured to modulate light from the light source.
15. The display system of claim 1 , wherein limiting displaying comprises:
determining an exposure time of the user to the virtual object, wherein the exposure time is a duration of exposure of the user to the virtual content while the virtual content is continuously located within the accommodation-vergence mismatch discomfort zone; and
refraining from displaying the virtual object within the accommodation-vergence mismatch discomfort zone after an exposure time threshold is exceeded.
16. The display system of claim 15 , wherein refraining from displaying the virtual object within the accommodation-vergence mismatch discomfort zone comprises stopping display of the virtual object to one eye of the viewer, while continuing to display the virtual object to an other eye of the viewer.
17. The display system of claim 15 , wherein refraining from displaying the virtual object within the accommodation-vergence mismatch threshold distance comprises intermittently stopping display of the virtual object to each eye of the viewer by alternating displaying the virtual object between the eyes of the viewer.
18. The display system of claim 15 , wherein the operations further comprise:
determining whether the virtual object is user-locked content or in-world content; and
setting the exposure time threshold based upon whether the virtual object is user-locked content or in-world content, wherein an associated exposure time threshold for in-world content exceeds an associated exposure time threshold for user-locked content.
19. The display system of claim 1 , further comprising sensors to determine an orientation of the eyes of the viewer, wherein the display system is configured to determine the vergence point based upon information from the sensors.
20. The display system of claim 19 , wherein the sensors comprise inwardly-facing cameras configured to image the eyes of the viewer.