Optical system for single camera stereo video

• US 5,835,133 A
• Filed: 01/23/1996
• Issued: 11/10/1998
• Est. Priority Date: 01/23/1996
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Moreton, Henry P., Loucks, Bryan E.
• Primary Examiner(s): Casler, Brian
• Assistant Examiner(s): DIN, LUANNE PAN
• Application Number:
  US08/590,347
• Time in Patent Office: 1,022 Days
• Field of Search: 348/49, 348/51, 348/52, 348/53, 348/54, 348/57, 348/58, 348/59, 348/39, 348/36, 348/38
• US Class Current: 348/49
• CPC Class Codes: G02B 30/24 involving temporal multiplexing, e.g. using sequentially activated left and right shutters
• CPC Class Codes: G03B 35/10 having single camera with stereoscopic-base-defining system
• CPC Class Codes: H04N 13/161 Encoding, multiplexing or demultiplexing different image signal components for multi-view video sequence encoding H04N19/597
• CPC Class Codes: H04N 13/189 Recording image signals; Reproducing recorded image signals
• CPC Class Codes: H04N 13/211 using temporal multiplexing
• CPC Class Codes: H04N 13/218 using spatial multiplexing
• CPC Class Codes: H04N 13/221 using the relative movement between cameras and objects
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/286 having separate monoscopic and stereoscopic modes
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 13/337 using polarisation multiplexing
• CPC Class Codes: H04N 13/341 using temporal multiplexing
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

A mechanism and method for recording stereo video with standard camera system electronics and a uniquely adapted optical assembly is disclosed. The optical assembly comprises left and right optical channels disposed to capture and project separate left and right images onto a single image sensor such that the boundary between the projected images is sharply delineated with no substantial overlap or gap. The viewpoints of the left and right optical channels are separated by a distance, d, such that the captured images are differentiated to produce a stereo image pair. By proper disposition of the left and right optical channels, stereo image pairs exhibiting full stereo overlap without keystone distortion are obtained. One image of the stereo pair is produced for visualization by the left eye and the other image is produced for visualization by the right eye. Alternatively, the images can be interrogated by a computer system for generating three dimensional position data. The image sensor is scanned in a standard fashion such that the left and right images are sampled by the video sampling circuitry of the camera unit at substantially the same time. In one mode, a pair of anamorphic lenses compress the left and right images along the axis of the image sensor scan lines so that each video field represents a stereo pair of images at a substantially unity anamorphic ratio and at an aspect ratio substantially equal to that of the image sensor. In a another mode, a conventional (non-distorting) lens is utilized and each video frame represents a pair of images having an aspect ratio equal to one-half that of the image sensor. A stereo playback mechanism and method is also disclosed.

Claims

1. A camera for generating a stereo video signal, said camera comprising:

an image sensor responsive to an image projected thereon;

an optical assembly having first and second optical channels that include respective focusing lenses disposed to focus substantially coincident portions of respective fields of view of the first and second optical channels onto abutting regions of said image sensor; and

a video generation circuit coupled to sample the abutting regions of said image sensor to generate said stereo video signal.

2. A camera as described in claim 1 wherein said video generation circuit samples the abutting regions of said image sensor substantially simultaneously.

3. A camera as described in claim 1 wherein the first and second optical channels have respective first and second viewpoints separated by a predetermined distance causing stereo differentiation between the respective fields of view of the first and second optical channels.

4. A camera as described in claim 1 wherein said video generation circuit samples said image sensor to generate video frames, each of the video frames including a left image and a right image corresponding to the portions of the respective fields of view of the first and second optical channels.

5. A camera as described in claim 4 wherein said image sensor has an aspect ratio and the left image and the right image each have an aspect ratio substantially equal to one-half the aspect ratio of said image sensor.

6. A camera as described in claim 1 wherein said video generation circuit samples said image sensor to generate video fields, each of the video fields representing one of the portions of the respective fields of view of the first and second optical channels.

7. A camera as described in claim 6 wherein the first optical channel and the second optical channel respectively comprise a first optical element and a second optical element to anamorphically reduce in a first axis the portions of the respective fields of view of the first and second optical channels so that images represented by each of the video fields each have a substantially unity anamorphic ratio.

8. A camera as described in claim 7 wherein said image sensor has an aspect ratio and the images represented by each of the video fields each have an aspect ratio substantially equal to the aspect ratio of said image sensor.

9. A camera for generating a stereo video signal, said camera comprising:

an image sensor responsive to an image projected thereon;

first and second optical channels having respective focusing lenses that are translatable in a direction transverse to their respective optical axes to project onto abutting regions of said image sensor portions of respective fields of view of the first and second optical channels that are substantially coincident; and

a video generation circuit coupled to sample the abutting regions of said image sensor to generate said stereo video signal.

10. A camera as described in claim 9 wherein said video generation circuit samples the abutting regions of said image sensor substantially simultaneously.

11. A video system for displaying a three dimensional view, said video system comprising:

an image sensor responsive to an image projected thereon;

an optical assembly having first and second optical channels that include respective focusing lenses disposed to focus substantially coincident portions of respective fields of view of the first and second optical channels onto abutting regions of said image sensor;

a video generation circuit coupled to sample the abutting regions of said image sensor to generate a stereo video signal; and

a video display device coupled to said video generation circuit for receiving the stereo video signal and to display a three dimensional view therefrom.

12. A video system as in claim 11 wherein said video display device comprises

a display;

a buffer memory to store the stereo video signal;

a display generator coupled to said buffer memory to sample from the stereo video signal stored therein a first image and a second image corresponding to the portions of respective fields of view of the first and second optical channels, said display generator alternately rendering the first and second images onto said display; and

a viewing device for viewing the first image rendered onto said display only by a first eye and for viewing the second image rendered onto said display only by a second eye, wherein the viewing by the first eye is alternated with the viewing by the second eye synchronously with the rendering of the first and second images onto said display.

13. In a camera, a method of generating a stereo video signal, said method comprising the steps of:

positioning a first focusing lens in a first optical assembly to select a portion of a field of view of the first optical assembly;

positioning a second focusing lens in a second optical assembly to select a portion of a field of view of the second optical assembly the portion of the field of view of the second optical assembly being substantially coincident with the portion of the field of view of the first optical assembly;

projecting the portions of the fields of view of the first and second optical assemblies onto respective abutting regions of an image sensor; and

sampling the abutting regions of the image sensor to generate said stereo video signal.

14. In a video system, a method of displaying a three dimensional view, said method comprising the steps of:

positioning a first focusing lens in a first optical assembly to select a portion of a field of view of the first optical assembly;

positioning a second focusing lens in a second optical assembly to select a portion of a field of view of the second optical assembly, the portion of the field of view of the second optical assembly being substantially coincident with the portion of the field of view of the first optical assembly;

projecting the portions of the fields of view of the first and second optical assemblies onto respective abutting regions of an image sensor; and

sampling the abutting regions of the image sensor to generate a stereo video signal; and

displaying a three dimensional view based on the stereo video signal.

15. A method as described in claim 14 wherein said step of displaying a three dimensional view includes the steps of:

storing the stereo video signal in a buffer memory;

sampling from the stereo video signal stored in the buffer memory first and second images corresponding to the portions of the fields of view of the first and second optical assemblies;

alternately rendering the first and second images onto a display; and

enabling a view, in a viewing device, of the first image rendered onto the display only by a first eye and of the second image rendered onto the display only by a second eye, wherein the viewing by the first eye is alternated with the viewing by the second eye synchronously with the rendering of the first and second images onto the display.

16. A method as described in claim 14 wherein said step of displaying a three dimensional view includes the steps of:

(a) reading a first video image comprised by a first video frame from a memory buffer pointed to by a read pointer and rendering the first video image onto a display the first video image corresponding to the portion of the field of view of the first optical assembly;

(b) reading a second video image comprised by the first video frame from the memory buffer pointed to by the read pointer and rendering the second video image onto the display, the second video image corresponding to the portion of the field of view of the second optical assembly;

(c) storing a second video frame from said stereo video signal in a memory buffer pointed to by a load pointer, said step of storing occurring within the time required to accomplish steps (a) and (b); and

(d) transposing the load and read pointers upon completion of steps (a) and (b);

(e) enabling a view of the first video image rendered onto the display only by a first eye; and

(f) enabling a view of the second video image rendered onto the display only by a second eye.

17. The method of claim 14 wherein said step of positioning a first focusing lens includes the step of translating the first focusing lens in a direction transverse to its optical axis.

18. A camera as described in claim 14 further comprising the step of anamorphically reducing the the respective portions of the fields of view of the first and second optical assemblies in a first axis.

19. A method as described in claim 18 wherein said step of displaying a three dimensional view includes the steps of:

(a) reading a first video image comprised by a first video field from a memory buffer pointed to by a read pointer and rendering the first video image onto a display, the first video image corresponding to the portion of the field of view of the first optical assembly;

(b) reading a second video image comprised by the first video field from the memory buffer pointed to by the read pointer and rendering the second image onto the display, the second video image corresponding to the portion of the field of view of the second optical assembly;

(c) storing a second video field from said stereo video signal in a memory buffer pointed to by a load pointer, said step of storing occurring within the time required to accomplish steps (a) and (b); and

(d) transposing the load and read pointers upon completion of steps (a) and (b);

(e) enabling a view of the first video image rendered onto the display only by a first eye; and

(f) enabling a view of the second video image rendered onto the display only by a second eye.