CAMERA CALIBRATION APPARATUS AND METHODS

• US 20170280135A1
• Filed: 06/24/2016
• Published: 09/28/2017
• Est. Priority Date: 03/22/2016
• Status: Active Grant

• Current Assignee: Blue River Technology Inc. (Deere & Company)
• Original Assignee: The LightCo Inc.
• Inventors: Shroff, Nitesh, Si, Weiguang, Reddy, Nagilla Dikpal, Sasinowski, John, Phan, Nghi, Bai, Jiamin, Singh, Harpuneet, Laroia, Rajiv
• Granted Patent: US 10,306,218 B2
• Time in Patent Office: Days
• 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 first camera holder;

a first test pattern; and

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 facing said first camera holder.

2. The camera calibration apparatus of claim 1, wherein said first test pattern includes multiple first test pattern portions.

3. The camera calibration apparatus of claim 2, 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 an opening corresponding the position of said camera holder.

4. The camera calibration apparatus of claim 1, 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 camera holder.

5. The camera calibration apparatus of claim 2, wherein each individual one of said 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.

6. The camera calibration apparatus of claim 5, 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 moveable support structure, said first mirror being mounted on a first side of said moveable support structure.

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

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

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 camera holder and a second position in which said second test pattern faces said camera holder.

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

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

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 the camera in said first camera holder.

11. The camera calibration apparatus of claim 10,

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 support structure rotating in response to rotation of said shaft of said motor.

12. The camera calibration apparatus of claim 11, further comprising:

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

a third test pattern surrounding said second camera holder.

13. 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.

14. The camera calibration apparatus of claim 13, 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.

15. The camera calibration apparatus of claim 14, further comprising one or more rows of lights to the side, bottom or top of said movable support for illuminating said first test pattern when said first mirror is facing said first test pattern.

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

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

17. A method of operating a camera test apparatus, the method comprising:

controlling one or more modules in a camera to capture an image of a first test pattern when a movable support on which a first mirror is in a mounted is in a first position, said first mirror facing the camera when the movable support is in the first position;

moving the movable support to a second position so that a second test pattern mounted on the movable support is facing the camera; and

controlling the one or more modules in the camera to capture an image of the second test pattern when the movable support is in the second position.

18. The method of claim 17, further comprising:

moving the movable support to a third position so that the first test pattern is visible to said camera after being reflected by said first mirror and a second mirror; and

controlling the one or more modules in the camera to capture an image of the first test pattern when the movable support is in the third position.

19. A controller for use in a camera test apparatus, the controller comprising:

memory including instructions for controlling movement of a movable support between different positions and to control a camera to take images while at said different positions; and

a processor configured to control the test apparatus in accordance with said instructions when said instructions are executed, said processor being configured to;

control one or more modules in a camera to capture an image of a first test pattern when a movable support, on which a first mirror is mounted, is in a first position, said first mirror facing the camera when the movable support is in the first position;

control a motor to move the movable support to a second position so that a second test pattern mounted on the movable support is facing the camera; and

control the one or more modules in the camera to capture an image of the second test pattern when the movable support is in the second position.

20. The controller of claim 19, wherein the processor is further configured to:

control the motor to move the movable support to a third position so that the first test pattern is visible to said camera after being reflected by said first mirror and a second mirror; and

control the one or more modules in the camera to capture an image of the first test pattern when the movable support is in the third position.