Methods and apparatus for bokeh codes

• US 8,366,003 B2
• Filed: 07/16/2010
• Issued: 02/05/2013
• Est. Priority Date: 07/23/2009
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Mohan, Ankit, Raskar, Ramesh, Smithwick, Quinn, Woo, Grace, Hiura, Shinsaku
• Primary Examiner(s): Hess, Daniel
• Assistant Examiner(s): Savusdiphol, Paultep
• Application Number:
  US12/838,304
• Publication Number:
  US 20110017826A1
• Time in Patent Office: 935 Days
• Field of Search: 235/454, 235/462.01, 235/462.05, 235/462.06, 235/462.09, 235/462.11, 235/462.22, 235/462.41, 235/487, 235/491, 235/494, 235/495, 235/486
• US Class Current: 235/462.11
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B

Abstract

In an illustrative implementation of this invention, an optical pattern that encodes binary data is printed on a transparency. For example, the pattern may comprise data matrix codes. A lenslet is placed at a distance equal to its focal length from the optical pattern, and thus collimates light from the optical pattern. The collimated light travels to a conventional camera. For example, the camera may be meters distant. The camera takes a photograph of the optical pattern at a time that the camera is not focused on the scene that it is imaging, but instead is focused at infinity. Because the light is collimated, however, a focused image is captured at the camera'"'"'s focal plane. The binary data in the pattern may include information regarding the object to which the optical pattern is affixed and information from which the camera'"'"'s pose may be calculated.

Claims

1. A system comprising, in combination:

an artificial light source for illuminating an optical pattern, which pattern encodes binary data;

the pattern; and

apparatus adapted for altering the direction of light rays from the pattern in such a way that

the light rays travel to a camera and pass through a lens of the camera, and

a focused image of at least a part of the pattern is captured by the camera at a time that the camera is focused at a depth other than the depth of the apparatus;

wherein the system is separate from and not part of a unified structure with the camera.

2. The system of claim 1, wherein the binary data includes information from which an angle of the camera relative to the apparatus may be determined.

3. A system comprising, in combination:

an optical pattern that encodes binary data; and

apparatus adapted for altering the direction of light rays from the pattern in such a way that

the light rays travel to a camera and pass through a lens of the camera, and

a focused image of at least a part of the pattern is captured by the camera while the camera is focused at a depth other than the depth of the apparatus;

wherein the apparatus does not comprise a lenticular lens, and wherein the system is separate from and not part of a unified structure with the camera.

4. The system of claim 3, wherein the apparatus is configured for collimating light from the apparatus in such a way that the light travels to the camera for imaging of at least part of the optical pattern while the camera is focused at infinity.

5. The system of claim 3, wherein the optical pattern comprises binary variations of optical appearance in two spatial dimensions, respectively.

6. The system of claim 3, wherein:

the lens comprises a spherical lens;

at least some of the binary data is arranged in a set of subpatterns;

each of the subpatterns in the set is unique within the pattern; and

which subpatterns are visible to the camera depends on angle of view.

7. The system of claim 3, wherein the binary data includes information for error correction.

8. The system of claim 3, wherein at least a portion of the binary data indicates a spatial position of the portion relative to the pattern.

9. The system of claim 3, wherein the optical pattern comprises a tiled pattern, and each particular tile in the tiled pattern, respectively, encodes spatial coordinates of the particular tile relative to the tiled pattern.

10. The system of claim 3, wherein:

the optical pattern that encodes the binary data has a total spatial area and

the apparatus is configured so that the camera may view a portion of the total spatial area and part of the binary data, and so that the portion of the total spatial area and the part of the binary data that is visible to the camera varies inversely with the distance between the camera and the apparatus.

11. The system of claim 3, further comprising the camera.

12. The system of claim 3, wherein the optical pattern is backlit at the time the camera images the pattern.

13. The system of claim 3, further comprising at least one radio frequency identification tag that is directly or indirectly affixed, or adapted to be directly or indirectly affixed, to the apparatus.

14. The system of claim 3, wherein the apparatus is affixed or adapted to be affixed to an automobile or other vehicle.

15. The system of claim 3, wherein the apparatus is adapted to display the optical pattern in such a way that the pattern changes over time.

16. Apparatus comprising, in combination:

an optical pattern that encodes binary data and

an optical system configured for altering the direction of light rays from the pattern in such a way that

the light rays travel to a camera and pass through a spherical lens of the camera, and

a focused image of at least a part of the pattern is captured by the camera while the camera is not focused at the depth of the apparatus;

wherein;

the apparatus is separate from and not part of a unified structure with the camera;

the binary data is arranged in a set of subpatterns,

each of the subpatterns in the set is unique within the optical pattern; and

a position of the camera relative to the apparatus may be determined from which of the subpatterns are visible to the camera.

17. The apparatus of claim 16, wherein the distance from the camera to the apparatus may be estimated from the size of a circle of confusion that the apparatus produces on the sensor plane.

18. The apparatus of claim 16, further comprising the camera.

19. The apparatus of claim 16, further comprising a digital processor for:

decoding bytes of the binary data, which bytes encode a position of the bytes in the optical pattern, and

based on the position, calculating a pose of the camera relative to an optical axis of the optical system.

20. The apparatus of claim 16, wherein the camera, alone or together with at least one other camera, is adapted for imaging a plurality of patterns, including the optical pattern, in or on objects worn by or affixed to a plurality of persons.

21. The apparatus of claim 16, wherein the apparatus does not include a cylindrical lens.

22. The system of claim 16, wherein the optical pattern comprises a tiled pattern, and each particular tile in the tiled pattern, respectively, encodes two dimensional spatial coordinates of the particular tile relative to the tiled pattern.

23. A method comprising using a camera to capture a focused image of a visual pattern, wherein

the pattern encodes binary data;

the pattern is two dimensional, comprising binary variations of optical appearance in two spatial dimensions, respectively;

an optical system alters the direction of light from the pattern before the light strikes the camera and passes through a lens of the camera,

the alteration of direction causes the captured image to be focused even though the camera is not focused at the depth of the pattern at the time the image is captured, and

both the pattern and the optical system are separate from, and not part of a unified structure with, the camera.

24. The method of claim 23, wherein the optical pattern comprises a tiled pattern, and each particular tile in the tiled pattern, respectively, encodes two dimensional spatial coordinates of the particular tile relative to the tiled pattern.

25. The method of claim 23, wherein:

the binary data is arranged in a set of subpatterns;

each of the subpatterns in the set is unique within the optical pattern; and

a position of the camera relative to the optical system may be determined from which of the subpatterns are visible to the camera.

26. A system comprising, in combination:

an optical pattern that encodes binary data; and

apparatus adapted for altering the direction of light rays from the pattern in such a way that

the light rays travel to a camera and pass through a lens of the camera, and

a focused image of at least a part of the pattern is captured at a sensor plane of the camera at a time that the camera is focused at infinity;

wherein the system is separate from and not part of a unified structure with the camera.

27. A system comprising, in combination:

an optical pattern that encodes binary data; and

apparatus adapted for altering the direction of light rays from the pattern in such a way that

the light rays travel to a camera and pass through a lens of the camera, and

a focused image of at least a part of the pattern is captured by the camera at a time that the camera is focused at a depth other than the depth of the apparatus;

wherein the system is separate from and not part of a unified structure with the camera.