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EP-3593530-B1 - METHOD TO CONTROL A VIRTUAL IMAGE IN A DISPLAY

EP3593530B1EP 3593530 B1EP3593530 B1EP 3593530B1EP-3593530-B1

Inventors

  • PETRUZZIELLO, FERNANDO
  • RADEL, JASON CARL

Dates

Publication Date
20260506
Application Date
20180306

Claims (8)

  1. A method for producing a virtual image focused for both eyes of an observer, the virtual image located closer than 60 feet (18,28 m) to the observer, the method executable by: a display screen (130, 230) displaying an original image, a computer system controlling the original image on the display screen, and a curved mirror (140, 240) having a curved mirrored surface opposing the display screen, the curved mirror configured to produce the virtual image of the original image; the method comprising: determining, by the computer system, a desired position of the virtual image, wherein the determining is: based on a location of the observer with respect to the curved mirrored surface, the virtual image being located at an angle greater than 5 degrees (°) from an axis of symmetry of the curved mirrored surface, and based on at least one of a parallax depth cue and a stereoscopic depth cue for the observer at the location of the observer, the at least one of the parallax depth cue and the stereoscopic depth cue being determined by taking into account that a production of the virtual image focused for both eyes of the observer is dependent on an angle from the axis of symmetry of the curved mirrored surface for the angle from the axis of symmetry greater than 5°; determining, by the computer system, a location of the original image on the display screen based on the desired position of the virtual image produced by the mirror and modifying mapping of the original image based on the determined location of the original image on the display screen; and rendering of the original image on the display screen at the location of the original image determined based on the desired position of the virtual image to produce the virtual image at the desired position and focused for both eyes of the observer.
  2. The method of claim 1, wherein determining, by the computer system, the location of the original image to be displayed on the display screen is further based on a shape of the display screen, a shape of the curved mirrored surface, and a distance d o between the location of the original image and the curved mirrored surface, the distance d o being determined along a primary ray traced from the position of the original image on the display screen to the observer via the curved mirrored surface, the distance d o being determined as: d o = d i R cos θ R cos θ − 2 d i , wherein θ is an angle between the primary ray and a normal to the curved mirrored surface, d i is the distance from the curved mirrored surface to the desired position of the virtual image, and R is a radius of a curvature of an osculating circle at the curved mirrored surface.
  3. The method of claim 1, wherein determining the desired position of the virtual image comprises determining a plurality of positions across the virtual image, thereby forming a shape of the virtual image.
  4. The method of claim 1, wherein determining the desired position of the virtual image comprises determining the at least one of the parallax depth cue and the stereoscopic depth cue for the location of the observer viewing the display screen through the curved mirrored surface at an angle greater than 10° from the axis of symmetry of the curved mirrored surface.
  5. The method of claim 1, wherein the display screen is one of: a rear projection screen and a front projection screen.
  6. The method of claim 1, further comprising correcting images displayed on the display screen based on the shape of the display screen, to modify rendering of the original image on the display screen at the location of the original image to provide at least one of parallax and a stereoscopic depth cue for the virtual image for the observer at the location.
  7. The method of claim 1, further comprising producing sound at a plurality of locations about the immersive display to make the sound having a source location consistent with the immersive image rendering.
  8. The method of claim 1, further comprising providing user controls for interacting with contents of the virtual image.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority or benefit of U.S. provisional patent application 62/467,846 filed March 7, 2017 and of U.S. provisional patent application 62/514,194 filed June 2, 2017. BACKGROUND (a) Field The subject matter disclosed generally relates to mirror optics. More specifically, it relates to the use of mirrored surfaces for display applications. (b) Related Prior Art The image of an object formed from the reflection of light rays from a mirrored surface is known as the virtual image of the object. Current standard methods for determining the location of a virtual image for non-planar mirrors or lenses are limited in two ways: 1) they are based on Gaussian optics, and therefore are only valid when both the observer and the object are near the optical axis of the lens or mirror, and/or2) they do not account for the different, conflicting depth cues used by a human observer to infer depth. The manner by which the generation of virtual images is controlled has an effect on the final result when the display is being used by an observer, especially when the display is used outside of the assumptions on which standard models underlying prior-art displays are based. A method for controlling the display of virtual images in non-planar mirrors such as spherical or parabolic mirrors for viewing angles away from the central axis of the mirror (e.g., 5°, or 10°, 15° or more away from its axis of symmetry) thus needs to be developed for a human observer. Various display applications, in particular immersive displays, can require mirrors to provide an immersive environment to users. These immersive displays exist in various types. Head-mounted displays (HMDs) are more widely used to immerse the wearer in virtual reality. By wearing the display in front of the eyes, and by including various optical systems in the display, the user is presented visual content that can adapt to the movement of the user's head, for example. However, the user is required to wear the HMD at all times to enjoy the immersive content, a situation that is not always desirable, especially if the user is to be immersed for long periods, e.g., for training in a flight simulator or for working in an immersive work station. Virtual reality and augmented reality systems must also be small enough to wear. Consequently, it is hard to incorporate high-resolution and high-quality displays. Virtual reality displays also suffer from the depth cue conflicts such as the vergence-accommodation conflict, i.e., the distance at which a viewer focuses their eyes to see the image clearly is not consistent with the distance they perceive the image via stereoscopic cues. Virtual reality displays also have problems with motion sickness. Front or rear projection-based display systems provide a simple setting creating an immersive experience for a user. Although relatively simple to install and convenient for many purposes, such as watching movies, these displays suffer from an unrealistic depth sensation, since images are projected onto a screen having a fixed distance to the viewers, and therefore the viewer is not completely immersed into the experience since there is no depth differentiation between objects in the image. In addition, depth cues between objects located outside the projection area and on the projection area are similar, which indicates to the brain that the observer is looking at a flat display located at a similar depth to the objects surrounding this display. These issues can be corrected in part by wearing 3D glasses which render the image stereoscopic, giving a sense of depth to the viewer. This can, however, be uncomfortable (especially for long-time use or for users already wearing glasses) and create a lack of realism since glasses need to be worn to reproduce a reality where no glasses would ordinarily be worn. These displays also suffer from the vergence-accommodation conflict. Another type of immersive display is the collimated display. Notably, flight simulators use a collimated display to provide an immersive environment. This industry makes use of concave mirrors to produce a virtual image that can be seen by both pilots in the cockpit with the exact same angle. A collimated display is one in which the display facing the user is not a conventional, but rather a reflecting screen (i.e., a convex mirror) on which an image is projected by a reflection on an intermediate display screen. These reflections are used to provide an image, as seen by the user, which is a virtual image created at infinity of the object (i.e., the display screen). The display screen is approximately positioned so that light reflecting from the surface will be nearly collimated after reflecting from the mirror. The image of an object formed from the reflection of light rays from a mirrored surface is known as the virtual image of the object. Current standard methods for determining the location of a virtual image for