WO1998034149A1

WO1998034149A1 - A viewer for simulating a stereoscopic view

Info

Publication number: WO1998034149A1
Application number: PCT/AU1998/000049
Authority: WO
Inventors: Julian Bernard Liddell
Original assignee: Blue Shift Technologies Pty. Ltd.
Priority date: 1997-01-30
Filing date: 1998-01-30
Publication date: 1998-08-06

Abstract

A viewer (1) for the presentation to a person of a simulation of a three-dimensional image from a single computer generated two-dimensional image mounts a converging Fresnel lens (13) in front of the person's eyes. The Fresnel lens (13) has not been corrected for chromatic aberration. The viewer (1) occludes the person's vision otherwise than through the Fresnel lens (13).

Description

Title of Invention: A VIEWER FOR SIMULAΉNG A STEREOSCOPIC VIEW

Technical Field:

This invention relates to simulation of three-dimensional images.

Background Art:

Graphics intensive computer based games have become popular in recent years with the development of high powered personal computers which have sophisticated graphics capabilities. Dedicated purpose computer gaming machines such as the "Nintendo", "Nintendo 64", "Sony Playstation" and "Sega Saturn console" have also become popular. These dedicated machines are microcomputers with limited functionality, designed specifically for games uses. Throughout this description, I use the term "computer" to include both a general purpose personal computer and a dedicated purpose, games computer.

Computer games generally provide stereo sound effects. It is, however, more difficult to provide computer games which have three-dimensional visual effects.

"Virtual reality" technology has been known for some time. This technology creates the illusion of movement in three-dimensional space, by providing images from offset view-points to each eye. For example, United States patents 5,091,719 (General Electric Company) and 5,347,400 (Hunter) describe helmet mounted optical systems for creation of virtual reality effects. Both of these patents describe the provision of independent images to each eye of the user, to create the illusion of stereoscopic vision.

Patent 5,347,400 describes such virtual reality systems as being used by, for example, engineers and architects for modeling and testing new designs, by doctors to practice an operation before it is conducted, and by military experts to simulate battlefield conditions. Such virtual reality systems use highly sophisticated computers utilising multisensory inputs and outputs to create an interactive virtual world in which a product, procedure or human response may be tested without the risks inherent in real-world trials.

More recently, there have been attempts to bring simulation of stereoscopic vision to games which run on far less sophisticated computers. One such attempt is

StereoGraphic's "CrystalEyes". "CrystalEyes" uses a conventional computer monitor for image display, in conjunction with specially written games software and a special headset. The headset incorporates liquid crystal display (LCD) shutters over each eye of the user. The software alternately displays on the monitor images from the viewpoint of one eye, and then the other. The software also alternately activates the LCD shutter in synchronism with the images, so that each eye sees only the image appropriate to that eye's viewpoint. This creates the illusion of a three-dimensional image.

In contrast, Chromatec Inc. of Alpharetta, Georgia has marketed apparatus which, unlike the prior art referred to above, does not require any form of computer control of optical elements in the optical path. This apparatus is in accordance with US patents 4,597,634, 4,717,239 and 5,002,364 (Steenblik). These patents describe the production of stereoscopic images from a single, specially colour coded two- dimensional image. The parts of the two-dimensional image which are to appear distant are coloured in red, whereas the parts of the image which are to appear in the foreground are coloured blue. The middle ground or intermediate distances are coloured green or yellow. This colour coded two-dimensional image is viewed with a prism or other diffraction element between each eye and the two-dimensional original. The prisms are oriented so that the virtual image of the blue components of the two-dimensional original is closer to the eyes than is the virtual image of the red components of the two-dimensional original, creating a stereoscopic view. The diffraction element may be a prism or combination of prisms, a Fresnel prism, or a diffraction grating. Although the Steenblik patents avoid the use of computer controlled optical elements in the optical path, they do require the use of a specially colour coded image.

It is an aim of the present invention to provide a method and apparatus which can create the illusion to the user of a three-dimensional image from a two-dimensional image without the necessity for providing either:

• computerised control of any optical element in the optical path from the two- dimensional image to the eyes; or • any specially encoded two-dimensional image.

The method and apparatus of the present invention work to produce the illusion of a three-dimensional image:

• not only from a two-dimensional graphical image displayed on a computer monitor;

• but also from a two-dimensional text display on a computer monitor, where the text characters and the background are displayed in different colours on the monitor.

Summary of the Invention:

This invention accordingly provides apparatus for the presentation to a person of a simulation of a stereoscopic view from a single two-dimensional image, the apparatus comprising: a converging lens which has not been corrected for chromatic aberration; means for mounting the lens between the two-dimensional image and the eyes of the person; and means for occluding the person's view otherwise than through the lens.

This invention also provides a method for presenting to a person a simulation of a stereoscopic view from a single two-dimensional image, the method comprising: producing a single virtual image, which image: is a magnification of the two-dimensional image; and which suffers from some degree of chromatic aberration; and occluding the person's view otherwise than of the virtual image.

In a preferred form of apparatus according to this invention, the focal length of the lens is between about 20cm and about 40cm.

In a further preferred form of the apparatus, the means for mounting the lens will mount the lens at between about 75mm and about 85mm from the person's forehead.

In a further preferred form of the apparatus, the lens is a Fresnel lens.

When the lens is a Fresnel lens, it is preferred that the lens be orientated such that, in use, the smooth surface of the lens is mounted closest to the person's eyes.

In a further preferred form of the apparatus, the means for mounting the lens between the two-dimensional image and the eyes of the person is a means for mounting the lens to the person's head.

In a further preferred form of the apparatus, the means for mounting the lens to the person's head is also the means for occluding that person's view otherwise than through the lens.

It is also preferred that the lens have a height of between 70mm and 80mm in orthogonal projection on a vertical plane and a width of between 165mm and

190mm in such projection on a vertical plane.

It is especially preferred that the lens have a height of about 75mm in orthogonal projection on a vertical plane and a width of about 180mm in such projection on a vertical plane. It is also preferred that the shape of the periphery of the lens in projection on a vertical plane be substantially elliptical.

It is also preferred that the apparatus be fabricated from light weight plastics material.

It is also preferred that the apparatus further comprises audio earphones.

A preferred form of the method according to this invention uses a lens which has a focal length of between about 20cm and about 40cm.

In a further preferred form of the method, the lens is mounted at between about 75mm and about 85mm from the person's forehead.

A further preferred form of the method uses a Fresnel lens.

When the method uses a Fresnel lens, it is preferred that the lens be orientated such that a smooth surface of the lens is closest to the person's eyes.

A further preferred form of the method mounts the lens between the two- dimensional image and the eyes of the person by mounting the lens to the person's head.

In a further preferred form of the method, the means for mounting the lens to the person's head also occludes that person's view otherwise than through the lens.

A further preferred form of the method uses a lens which has a height of between 70mm and 80mm in orthogonal projection on a vertical plane and a width of between 165mm and 190mm in such projection on a vertical plane. An especially preferred form of the method uses a lens which has a height of about 75mm in orthogonal projection on a vertical plane and a width of about 180mm in such projection on a vertical plane.

It is also preferred that the shape of the periphery of the lens in projection on a vertical plane be substantially elliptical.

In a further preferred form of the method according to the invention, stereo sound is provided to the person via audio ear phones.

Specific embodiments of apparatus and the method in accordance with this invention will now be described by way of non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings:

Figure 1 is a side elevational view, partially cut away, of one form of apparatus according to the present invention.

Figure 2 is plan view of the apparatus of figure 1.

Figure 3 is a front elevational view of the apparatus of figure 1.

Figure 4 is a side elevational view, partly in section, of the apparatus of Figure 1 in use.

Figure 5 is a partial side elevational view of another embodiment of apparatus according to the present invention.

Detailed Description of the Preferred Embodiments: Figures 1 to 3 show a headset 1. The headset 1 is fabricated from light weight plastics material, and has side legs 2 and 3 with downwardly turned ends 4 and 6. Side legs 2 and 3 expand into side walls 7 and 8. The side walls 7 and 8 are contiguous with top and bottom sides 11 and 12. Edge 16 of top side 11 is shaped to generally conform to the shape of a person's forehead. The corresponding edge 20 of bottom side 12 is similarly shaped to conform to the contours of a person's face below the eyes. Edge 17 of side wall 7, and the corresponding edge 21 of side wall 8, are configured to snugly fit to the region of a person's head between the eyes and the ears.

As shown in Figures 1 and 3, a converging Fresnel lens 13 is mounted in the opening defined by the side walls 7 and 8 and the top and bottom sides 11 and 12.

The Fresnel lens 13 is secured in this opening by moulded lips 22 and 23, which protrude from the top, bottom and sides of the inner shell of the lens headset 1.

Compared with spherical lenses, Fresnel lenses have their curves reduced from large curved faces to a series of equivalently curved rings or steps. Fresnel lenses accordingly have one rough face and one smooth face. It is particularly preferred that the Fresnel lens according to the present embodiment be mounted so that, in use, the smooth face of the lens is towards the user's eyes. This orientation of the lens appears to minimise pincushion distortion when viewing an image on a monitor.

Figure 4 shows a person 25 wearing a headset to view a monitor shown in partial outline at 26. The Fresnel lens 13 has a focal length of between about 20cm and 40cm. Preferably, the lens has a focal length of about 25cm. The distance 27 between edge 16 and the centre plane of lens 13 is in the range of about 75mm to

85mm. Preferably, this distance is about 80mm. Preferably, the lens is about 75mm high and about 180mm wide.

The actions of the apparatus in: • producing chromatic aberration;

• producing a magnified virtual image; and • occluding the persons view other than through the lens all appear to contribute to the creation of the illusion of a stereoscopic view.

How large an image appears, and how much detail can be seen in it, depends on the angle which the image subtends at the eye. For example, a 20 cent coin held 30cm from the eye looks twice as high as does one which is held 60cm from the eye, because the angle which it subtends is twice as great. To examine detail on the object, we bring it up close to our eyes so that it subtends a greater angle. However, our eyes can accommodate only up to a point. The nearest point at which an eye can focus clearly is called the near point. The near point varies from person to person, although a good average is about 25cm.The most distant point that can be focused clearly by the eye is called the far point. The eye focuses on the far point when the muscles of the eye are relaxed. For a "normal" eye the far point is quite large, and we take it to be infinity.

The focal length of the lens 13, and the dimensioning of the headset 1, have been chosen such that people who have eyesight within a wide range can use the apparatus comfortably.

The chromatic aberration of the lens produces different virtual images for different wavelengths of light. For example, when the apparatus is being used for viewing red text which is displayed against a blue background, the chromatic aberration of the lens will produce two virtual images, one of the red text and one of the blue background. The virtual image of the red text is closer to the viewer than is the virtual image of the blue background.

In a further preferred embodiment according to the invention shown in Figure 5 the headset is fitted with adjustable audio headphones 30 to give the user sound as well as sight. The headphones 30 are provided integrally in extensions 31 which depend from each of side legs 2 and 3 of the apparatus. Such extensions may be flexible or extensible or both to conform to the requirements of the user. In yet a further embodiment (not illustrated) instead of the headphones being mounted integrally in such extensions, the extensions may be provided with means for demountably carrying headphones.

Testing has shown that the illusion of a three dimensional virtual image which is created by the combined effect of magnification and chromatic aberration is then enhanced by the "blinkering" effect of occluding the person's peripheral vision.

Claims

1. A three-dimensional viewer for the presentation to a person of a simulation of a stereoscopic view from a single two-dimensional image, the viewer comprising: a converging lens which has not been corrected for chromatic aberration; means for mounting the lens between the two-dimensional image and the eyes of the person; and means for occluding the person's view otherwise than through the lens.

2. A viewer according to claim 1 , in which the focal length of the lens is between about 20cm and about 40cm.

3. A viewer according to claim 1 or claim 2 in which the means for mounting the lens will mount the lens at between about 75mm and about 85mm from the person's forehead.

4. A viewer according to any one of the preceding claims in which the lens is a Fresnel lens.

5. A viewer according to claim 4 in which the lens is orientated such that, in use, the smooth surface of the lens is mounted closest to the person's eyes.

6. A viewer according to any one of the preceding claims in which the means for mounting the lens between the two-dimensional image and the eyes of the person is a means for mounting the lens to the person's head.

7. A viewer according to claim 6 in which the means for mounting the lens to the person's head is also the means for occluding that person's view otherwise than through the lens.

8. A viewer according to any one of the preceding claims in which the lens has a height of between 70mm and 80mm in orthogonal projection on a vertical plane and a width of between 165mm and 190mm in such projection on a vertical plane.

9. A viewer according to claim 8 in which the lens has a height of about 75mm in orthogonal projection on a vertical plane and a width of about 180mm in such projection on a vertical plane.

10. A viewer according to any one of the preceding claims in which the shape of the periphery of the lens in projection on a vertical plane is substantially elliptical.

11. A viewer according to any one of the preceding claims which is fabricated from light weight plastics material.

12. A viewer according to any one of the preceding claims, further comprising audio earphones.

13. A viewer according to any one of claims 1 to 11, further comprising means for mounting audio earphones.

14. A method for presenting to a person a simulation of a stereoscopic view from a single two-dimensional image, the method comprising: producing a single virtual image, which image: is a magnification of the two-dimensional image; and which suffers from some degree of chromatic aberration; and occluding the person's view otherwise than of the virtual image.

15. A method according to claim 14 wherein the lens has a focal length of between about 20cm and about 40cm.

16. A method according to claim 14 or claim 15, wherein the lens is mounted at between about 75mm and about 85mm from the person's forehead.

17. A method according to any one of claims 14 to 16, wherein the lens is a

Fresnel lens.

18. A method according to claim 17, wherein the Fresnel lens is orientated such that a smooth surface of the lens is closest to the person's eyes.

19. A method according to any one of claims 14 to 18 wherein the lens is mounted between the two-dimensional image and the eyes of the person by mounting the lens to the person's head.

20. A method according to claim 19 wherein the means for mounting the lens to the person's head also occludes that person's view otherwise than through the lens.

21. A method according to any one of claims 14 to 20 in which the lens has a height of between 70mm and 80mm in orthogonal projection on a vertical plane and a width of between 165mm and 190mm in such projection on a vertical plane.

22. A method according to claim 21 in which the lens which has a height of about 75mm in orthogonal projection on a vertical plane and a width of about 180mm in such projection on a vertical plane.

23. A method according to any one of claims 14 to 22 in which the shape of the periphery of the lens in projection on a vertical plane is substantially elliptical.

24. A method according to any one of claims 14 to 23 in which stereo sound is provided to the person via audio ear phones.