Camera calibration apparatus and methods

• US 10,306,218 B2
• Filed: 06/24/2016
• Issued: 05/28/2019
• Est. Priority Date: 03/22/2016
• Status: Active Grant

• Current Assignee: Blue River Technology Inc. (Deere & Company)
• Original Assignee: Light Labs Inc.
• Inventors: Shroff, Nitesh, Si, Weiguang, Reddy, Nagilla Dikpal, Sasinowski, John, Phan, Nghi, Bai, Jiamin, Singh, Harpuneet, Laroia, Rajiv
• Primary Examiner(s): Yenke, Brian P
• Assistant Examiner(s): Haiem, Sean N.
• Application Number:
  US15/192,300
• Publication Number:
  US 20170280135A1
• Time in Patent Office: 1,068 Days
• Field of Search: 348188, 348187, 348 51, 359877, 606 4, 356124
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: H04N 17/002 for television cameras

Abstract

An exemplary camera calibration apparatus includes a movable, e.g., rotatable, support structure which is controllably positioned to allow for image capture of different test patterns and image capture of the same pattern at different distances by a mounted camera. A first test pattern is mounted on a wall, e.g., a pyramid shaped 4 sided wall formed by panels surrounding the camera under calibration. The movable support structure has a first mirror attached to a first side and has a second test pattern attached to a second side. A second mirror mounted on an internal sidewall of the calibration apparatus housing facilities a different image path distance between the camera capturing the image of the first test pattern and the first test pattern. The exemplary camera calibration apparatus is well suited for efficiently calibrating camera devices including a plurality of camera modules, e.g., optical chains, in a relatively small area.

Claims

1. A camera calibration apparatus, comprising:

a housing;

a first camera holder including a view opening through which an interior portion of the housing is visible or viewing window through which the interior portion of the housing is visible;

a first test pattern including a first test pattern portion, said first test pattern portion being positioned along a first sidewall portion of the housing, said first sidewall portion extending at an angle away from said first camera holder and to the left or right of said first camera holder;

a first mirror for reflecting an image of the first test pattern to a camera in said first camera holder when said first mirror is in a first position physically in front of and physically facing both i) said first camera holder and ii) said first test pattern;

a moveable support structure, said first mirror being mounted on a first side of said moveable support structure;

a second test pattern mounted on a second side of said moveable support structure;

a motor attached to said movable support structure for driving said moveable support structure between different positions, said different positions including a first position in which said first mirror faces said first test pattern and said first camera holder and a second position in which said second test pattern faces said first camera holder; and

a second mirror mounted on a first sidewall of the housing in which said moveable support structure is positioned;

wherein said motor is also for driving said movable support structure to a third position in which said first test pattern is reflected in said first and second mirrors making the reflection visible to a camera in said first camera holder;

wherein said motor is mounted in a roof of said housing; and

wherein said moveable support structure is mounted on a shaft of said motor, said moveable support structure rotating in response to rotation of said shaft of said motor.

2. The camera calibration apparatus of claim 1,

wherein said first test pattern includes four sloped test pattern panels that form said first test pattern, said first test pattern portion being a first test panel which is one of said four sloped test pattern panels, said first test pattern surrounding said first camera holder;

wherein said first camera holder is located on a first side of said housing and

wherein said first test pattern is included on the first side of said housing on which said first camera holder is located.

3. The camera calibration apparatus of claim 1,

wherein said first camera holder is located on a first side of said housing;

wherein said first test pattern includes multiple first test pattern portions, said first test pattern being located on the first side of said housing; and

wherein each of the multiple first test pattern portions are mounted on different panels, said different panels being angled to form a sloped surface surrounding the view opening or viewing window.

4. The camera calibration apparatus of claim 1,

wherein said first test pattern portion is part of a first test pattern;

wherein said first test pattern includes four first test pattern portions, each one of the four first test pattern portions being mounted on one of four different panels, said four panels being angled to form a sloped surface surrounding an opening corresponding the position of said first camera holder; and

wherein said first mirror is positioned inside said housing at a location between said first sidewall and a second sidewall of said housing.

5. The camera calibration apparatus of claim 2, wherein the first test pattern positioned along a first sidewall portion of the housing is positioned to the right or left of said view opening or viewing window.

6. The camera calibration apparatus of claim 2,

wherein each individual one of multiple first test pattern portions of said first test pattern includes an identifying mark which distinguishes the individual one of the multiple first test panel portions from the other ones of the multiple first test panel portions;

and

wherein said first test pattern also includes at least one orientation indicator which can be used to distinguish a top of the individual test pattern portion from a bottom of the individual test pattern portion.

7. The camera calibration apparatus of claim 1,

wherein said camera calibration apparatus includes a non-uniform illumination source for illuminating said first test pattern;

and

wherein said first test pattern includes a plurality of different color patches, a uniform color reference area being positioned adjacent individual color patches to serve as illumination reference areas.

8. The camera calibration apparatus of claim 1, further comprising:

a second camera holder located opposite said first camera holder, said moveable support structure being positioned between said first and second camera holders; and

a third test pattern surrounding said second camera holder.

9. The camera calibration apparatus of claim 1, further comprising:

rows of lights positioned in front of and on the left and right sides of said first test pattern.

10. The camera calibration apparatus of claim 9, further comprising at least one row of lights positioned below and in front of said first test pattern or above and in front of said first test pattern for illuminating said second test pattern when the second test pattern is facing said first camera holder.

11. The camera calibration apparatus of claim 10, further comprising one or more rows of lights to the side, bottom or top of said moveable support for illuminating said first test pattern when said first mirror is facing said first test pattern.

12. The camera calibration apparatus of claim 2, further comprising:

a moveable support position and camera controller for controlling the position of said moveable support structure to switch between different predetermined positions and for controlling the camera mounted in said first camera holder to operate camera modules included in said camera to capture images when said moveable support structure is at multiple different ones of said predetermined positions.

13. The camera calibration apparatus of claim 1, wherein said first camera holder is outside said interior portion of the housing.

14. The camera calibration apparatus of claim 13,

wherein said first camera holder is mounted on the outside of said housing and includes a space for holding a portable camera to be calibrated.