Camera Alignment and/or Calibration Methods and Apparatus

• US 20180020206A1
• Filed: 07/15/2017
• Published: 01/18/2018
• Est. Priority Date: 07/15/2016
• Status: Active Grant

• Current Assignee: Nevermind Capital LLC
• Original Assignee: NextVR, Inc. (Apple Inc.)
• Inventors: Sheridan, Ryan Michael
• Granted Patent: US 10,715,788 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 30/26 of the autostereoscopic type
• 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 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/327 Calibration thereof
• CPC Class Codes: H04N 2213/001 Constructional or mechanical details

Abstract

Methods and apparatus for aligning components of camera assemblies of one or more camera pairs, e.g., a stereoscopic camera pairs, are described. A camera calibration tool referred to as a camera bra is used. Each dome of the camera bra includes a test pattern, e.g., grid of points, with the domes being aligned and spaced apart by a predetermined amount. The bra is placed over the cameras of a camera pair, the grids are detected and displayed. The camera component positions are adjusted until the displayed images show the grids as being properly aligned. Because the grids on the calibration tool are properly aligned as a result of the manufacturing of the calibration tool, when the images are brought into alignment the cameras will be properly spaced and aligned at which point the calibration tool can be removed and the stereoscopic camera pair used to capture images of a scene.

Claims

1. A camera calibration tool, comprising:

a first dome; and

a second dome, said first and second domes being rigidly attached to each other by a attachment member that secures the first dome to the second dome.

2. The camera calibration tool of claim 1, wherein each of said first and second domes includes a plurality of light emitting elements or marks forming a pattern on the inside surface of said domes.

3. The camera calibration tool of claim 2, wherein said grid pattern matches a larger test pattern used for individually calibrating first and second cameras prior to said camera pair calibration tool (200) being placed over said first and second cameras.

4. The camera calibration tool of claim 2, wherein where said light emitting elements are fibers to which a light source supplies light, each fiber passing through a hole in one of said first and second domes.

5. The calibration tool of claim 2, wherein said light source supplies a first color of light to the light emitting elements of the first dome and supplies a second color of light to the light emitting elements of the second dome, said second color of light being different from said first color of light.

6. The camera calibration tool of claim 4, where said tool is a printed plastic calibration tool.

7. The camera calibration tool of claim 5, wherein the openings at the base of each of said first and second domes are of a size which allows said calibration tool to be placed over the lenses of said first and second cameras and be held in place by friction.

8. The camera calibration tool of claim 7, wherein said tool is a printed plastic tool and where said plastic blocks the transmission of light except though the holes into which fiber optic lines are inserted to supply light at the predetermined points of the test pattern which is visible from inside each dome of the calibration tool.

9. A method of calibrating a stereoscopic camera pair, comprising:

capturing a first image using a first camera of the stereoscopic camera calibration pair while a calibration bra is placed over the lenses of the stereoscopic camera pair;

displaying the first image on a display device along with an alignment target;

adjusting the position of at least a portion of the first camera, to align one or more captured calibration marks captured by the first camera, with the alignment target.

10. The method of claim 9, wherein the captured calibration marks are points of light corresponding to holes in a first dome of the calibration bra.

11. The method of claim 10, further comprising:

capturing a second image using a second camera of the stereoscopic camera calibration pair while the calibration bra is placed over the lenses of the stereoscopic camera pair;

displaying the second image on the display device along with the alignment target.

12. The method of claim 11, further comprising:

adjusting the position of at least a portion of the second camera to align one more captured calibration marks captured by the second camera with the alignment target.

13. The method of claim 12, wherein displaying the second image on the display device along with the alignment target includes:

superimposing the second image over an image captured by the first camera.

14. The method of claim 9,

wherein the portion of the first camera is a lens and sensor assembly;

and

wherein a processor of the first camera is coupled to a first camera sensor included in the lens and sensor assembly by a cable.

15. The method of claim 9,

wherein the portion of the first camera is the entire first camera.

16. A system for calibrating stereoscopic camera pairs, the system comprising:

a first dome;

a second dome, said first and second domes being rigidly attached to each other by a attachment member that secures the first dome to the second dome; and

a plurality of optical fibers extending into holes in said first and second domes.

17. The system of claim 17, further comprising:

a light source for supplying light to the optical fibers extending through holes in said first dome and the second dome.

18. The system of claim 17, wherein said light source supplies different color light to the optical fibers extending into the first dome than to the optical fibers extending into the second dome.

19. The system of claim 17, further comprising:

a display device for displaying a first image captured by a first camera of a stereoscopic camera pair to be calibrated superimposed on an alignment mark.

20. The system of claim 19, wherein the display device if further configured to display a second image captured by a second camera of the stereoscopic camera pair, to be calibrated superimposed on the alignment mark and the first image captured by the first camera of the stereoscopic camera pair.