Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1998-10-30
2004-11-09
Wong, Don (Department: 2770)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C348S048000
Reexamination Certificate
active
06816158
ABSTRACT:
FIELD OF INVENTION
These inventions relate to three-dimensional (3-D) display systems and methods, and, in particular, to a 3-D display system and method in which 3-D viewing is permitted at multiple viewing positions, such as multiple viewing angles or distances, from the screen.
BACKGROUND OF INVENTION
Creating the illusion of three-dimensional (3-D) images on a 2-D display device or projection screen has been attempted for many years. In the 1950's, 3-D movies were popular with polarized glasses worn to separate images for the left and right eye to provide for a stereoscopic view of the movie. Another area in which 3-D imagery has been attempted is on raster scan displays. Generally, when the term 3-D is used in regard to computer graphics, the term is referring to planar generated 3-D images that are created using geometric perspective and projection transformations and other monocular depth cues such as hidden line removal, surface modeling, shading, texture mapping, and rotation. These techniques are appropriate for computer games and CAD application software but not for viewing camera-generated images such as used by the television industry.
Stereoscopic images present the viewer with slightly different perspectives for the left and right eyes which fuse together to provide a sense of depth, in a process called stereopsis. Stereoscopic displays typically require the use of some device worn by the viewer to separate the left and right eye perspectives. Autostereoscopic displays make use of some device externally attached to the 3-D display to generate the left and right views without the aid of a special viewing aid worn by the viewer. These devices are lenticular screens, light valves, floating displays, or other types of devices.
Autostereoscopic 3-D methods are preferred because of elimination of the need for special glasses to separate the left and right eye images. The lenticular screen has been investigated extensively for use in autostereoscopic displays. The lenticular screen uses vertically oriented stereoscopic image pairs and focuses them at the proper point for viewing. Using a fixed image under the lenticular screen will only allow one viewer to be in focus with the 3-D image.
Prior art patents have presented different methods for generation of 3-D displays. Several prior art displays use the concept of generating vertical stereoscopic image strips projected onto the back of a lenticular screen. See, e.g., U.S. Pat. Nos. 4,541,007; 4,214,257; 5,430,474; 5,614,941; 4,872,750.
It is known that by multiplexing two camera signals and generating stereoscopic images projected to a lenticular screen that a 3-D image is able to be viewed. See e.g., U.S. Pat. No. 4,214,257. However, U.S. Pat. No. 4,214,257 does not provide for more than a single user.
It is also known that if five camera signals are multiplexed and properly placed in horizontal succession behind a lenticular screen, multiple viewing locations are obtained. See e.g., U.S. Pat. No. 4,541,007.
It is also known that 3-D displays are created by floating one image above another using devices such as the LCD. See e.g., U.S. Pat. Nos. 5,430,474 and 5,614,941. U.S. Pat. Nos. 5,430,474 and 5,614,941 disclose different concepts for generation of 3-D displays as they do not generate vertical image strips for presentation to the lenticular screen.
It is further known that the time multiplexing of camera images are used to present 3-D autostereoscopic images to multiple viewers by use of a LCD shutter device. See e.g., Moore, J. R., Dodgson, N. A., Travis, A. R. L., and Lang, S. R. “Time-Multiplexed Color Autostereoscopic Display.” Proc. SPIE, Vol. 2653, pp. 10-19, 1996. This research performed at the University of Cambridge discloses the use of a LCD shutter device which is a different method for providing multiple viewing locations.
It is also known that 3-D images projected onto a lenticular screen follow a single user with a sensor attached to the user. The system uses mirrors to horizontally shift and change the size of the image to provide for horizontal and distance changes appropriate for the viewer to maintain sight of the 3-D image. See e.g., Tetsutani, N., Kishino, F. “3-Dimensional Display Method without Special Glasses for Virtual Space Teleconferencing System” Proc. SPIE, Vol. 1988, pp. 18-25, 1993. However, this projection system does not allow the flexibility and accuracy of a software-based system.
Each of the patents and articles discussed above is incorporated herein by reference.
Furthermore,
FIGS. 1
to
4
illustrate the workings of a conventional prior art autostereoscopic 3-D system using two cameras A (
2
) and B (
4
) and employing a lenticular screen
12
.
FIG. 1
demonstrates the basic principle of a conventional prior art two camera 3-D autostereoscopic display system
1
incorporating a lenticular screen
12
. Cameras A (
2
) and B (
4
) generate analog video signals that represent the left and right eye perspective views of the image object
6
. These video signals are of any type (NTSC, PAL, SECAM, etc.) that are displayable on raster scan display devices
10
. The respective analog video signals
3
and
5
from the cameras A (
2
) and B (
4
) are input to the graphics controller
8
. The graphics controller
8
digitizes the analog signal so that processing of the signals
3
and
5
is accomplished with a digital signal processor or application specific graphics processor. The graphics processor multiplexes the left and right eye perspective views to create a stereoscopic image for the display with the proper timing. Once the stereoscopic raster image has been created digitally, it is then properly conditioned to form a signal
14
meeting the input requirements of the specific type of display device
10
being used. The lenticular screen
12
focuses the raster scan stereoscopic images to the proper locations for the viewer
16
.
FIG. 2
shows conventional prior art views of left and right image strips showing two different perspectives derived from the two cameras A (
2
) and B (
4
) of the same image. These views demonstrate how the stereoscopic images appear on the display device
10
as seen in FIG.
1
. The left view
20
and right view
18
are shown separately for illustration purposes only. The left view
20
shows the vertical strips of the stereoscopic image, which is generated from camera A (
2
), and the right view
18
shows the vertical strips of the image from camera B (
4
). These images represent the position of the image as displayed for one viewing location. For other viewing locations, the same vertical strips are shifted horizontally by small amounts.
To be able to view the stereoscopic image pairs, they must be aligned properly with the lenticular screen
12
. The lenticular screen
12
has many individual lenses called lenticules
19
. The lenticules
19
are vertically oriented convex lenses attached parallel to each other. For example, the display on display device
10
appears on the lenticular screen
12
as shown in FIG.
3
.
FIG. 3
shows a view of a stereoscopic image pair that appears on the back of one lenticule
19
in the lenticular screen
12
. Each of the lenticules
19
has one vertical strip
32
of the stereoscopic image for the left eye
26
and one strip
34
for the right eye
24
. The adjacent lenticules
19
have a strip of the camera views corresponding to the image shifted to the left or right. The position of the image strips
32
and
34
represent one viewing location.
To focus each of the stereoscopic image pairs
32
and
34
to the proper eye
26
and
24
, they must be placed in unique locations at the back of the lenticules
19
. Referring to
FIG. 4
, the vertical images are placed at the back of the lenticules
19
to maintain the proper stereoscopic relationship. The left view strips
32
and right view strips
34
placed at the back of the lenticules
19
respectively provide left eye
26
and right eye
24
stereoscopic views which are in focus for the lenticules
19
. With all image strips placed in the proper
Blake Tracy D.
Lemelson Dorothy
Lemelson Jerome H.
Pedersen Robert D.
Cao Huedung X.
Lemelson Dorothy
Rudy Douglas W.
Suominen Edwin A.
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