Calibration system and method for multi-camera vision system

• US 9,688,200 B2
• Filed: 03/03/2014
• Issued: 06/27/2017
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Original Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Inventors: Knudsen, Timor
• Primary Examiner(s): Huang, Frank
• Application Number:
  US14/195,135
• Publication Number:
  US 20140247354A1
• Time in Patent Office: 1,212 Days
• CPC Class Codes: B60R 2300/105 using multiple cameras
• CPC Class Codes: B60R 2300/402 Image calibration
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/30208 Marker matrix
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/85 Stereo camera calibration

Abstract

A calibration system for a multi-camera vision system of a vehicle includes a plurality of calibration targets disposed at an area at which the vehicle is positioned for a calibrating procedure. The calibration targets may include a patterned array of markings, such as colored or black/white or shaded markings or dots, disposed at forward, rearward and/or sideward regions of the vehicle. The control is operable to process image data captured by the cameras and, responsive to processing of captured image data, the control is operable to determine a particular local pattern of markings of the respective calibration target to determine the position of the respective calibration target relative to the camera that is imaging that target. Responsive to processing of captured image data, the calibration system is operable to calibrate the multi-camera vision system of the vehicle.

Claims

1. A calibration system for a multi-camera vision system of a vehicle, said calibration system comprising:

a first camera disposed at a vehicle and having a first field of view rearward of the vehicle;

a second camera disposed at the vehicle and having a second field of view generally sideward of the vehicle at a driver side of the vehicle;

a third camera disposed at the vehicle and having a third field of view generally sideward of the vehicle at a passenger side of the vehicle;

first, second and third calibration targets disposed at an area at which the vehicle is positioned for a calibrating procedure;

wherein said first calibration target is encompassed by said first field of view of said first camera;

wherein said second calibration target is encompassed by said second field of view of said second camera;

wherein said third calibration target is encompassed by said third field of view of said third camera;

wherein each of said calibration targets comprises an irregular patterned array of markings, and wherein the pattern of said irregular patterned array of markings is irregular at each of said calibration targets;

a control comprising an image processor operable to process image data captured by said first, second and third cameras;

wherein said control stores in memory the respective irregular patterns of said markings of said first, second and third calibration targets;

wherein said control is operable to process image data captured by said cameras that are being calibrated, and wherein, responsive to processing of image data captured by said cameras, said control determines a particular local irregular pattern of markings of the respective calibration target viewed by a respective one of said cameras;

wherein said control determines, via comparing determined particular local irregular patterns of markings of the respective calibration target to the respective stored in memory irregular patterns of markings of said first, second and third calibration targets, the position of the respective calibration target relative to the respective camera; and

wherein, responsive to processing of captured image data, said calibration system is operable to calibrate said multi-camera vision system.

2. The calibration system of claim 1, wherein said irregular patterned array of markings of said calibration targets comprises irregular pierced dot arrays.

3. The calibration system of claim 1, wherein said irregular patterned array of markings of said calibration targets comprises an irregular patterned array of dots arranged in an irregular pattern.

4. The calibration system of claim 3, wherein said irregular patterned array of dots comprises an irregular patterned array of circular dots.

5. The calibration system of claim 3, wherein said irregular patterned array of dots of said calibration targets comprises at least one of (i) a plurality of different colored dots arranged in an irregular color pattern, (ii) a plurality of black and white dots arranged in an irregular pattern, (iii) a plurality of differently shaded dots arranged in an irregular pattern.

6. The calibration system of claim 3, wherein said calibration system is operable to determine the position of a particular calibration target with respect to a particular camera based on the irregular pattern of dots of a sub-array of dots detected by the particular camera.

7. The calibration system of claim 1, wherein said irregular patterned array of markings comprises a plurality of sub-arrays of irregular markings and wherein no one sub-array is the same as any other sub-array of said irregular patterned array of markings.

8. The calibration system of claim 1, wherein, responsive to processing of captured image data, said calibration system is operable to determine the vehicle model.

9. The calibration system of claim 1, wherein, responsive to processing of captured image data, said calibration system is operable to calibrate vision systems of multiple types or sizes of vehicles positioned at said calibration targets.

10. The calibration system of claim 1, comprising a fourth camera disposed at the vehicle and having a fourth field of view forward of the vehicle, wherein a fourth calibration target is disposed at the area at which the vehicle is positioned for the calibrating-procedure, and wherein said fourth calibration target is encompassed by said fourth field of view of said fourth camera, and wherein said image processor is operable to process image data captured by said fourth camera, and wherein, responsive to processing of image data captured by said fourth camera, said control is operable to determine a particular local pattern of irregular markings of said fourth calibration target viewed by said fourth camera, and wherein said control determines, via comparing the determined particular local irregular pattern of markings of said fourth calibration target to a stored in memory irregular pattern of markings of said fourth calibration target, the position of said fourth calibration target relative to said fourth camera.

11. A calibration system for a multi-camera vision system of a vehicle, said calibration system comprising:

a first camera disposed at a vehicle and having a first field of view rearward of the vehicle;

a second camera disposed at the vehicle and having a second field of view generally sideward of the vehicle at a driver side of the vehicle;

a third camera disposed at the vehicle and having a third field of view generally sideward of the vehicle at a passenger side of the vehicle;

first, second and third calibration targets disposed at an area at which the vehicle is positioned for a calibrating procedure;

wherein said first calibration target is encompassed by said first field of view of said first camera;

wherein said second calibration target is encompassed by said second field of view of said second camera;

wherein said third calibration target is encompassed by said third field of view of said third camera;

wherein each of said calibration targets comprises an irregular patterned array of markings, and wherein the pattern of said irregular patterned array of markings is irregular at each of said calibration targets;

wherein said irregular patterned array of markings comprises at least one of (i) a plurality of different colored markings arranged in an irregular color pattern, (ii) a plurality of black and white markings arranged in an irregular pattern, (iii) a plurality of differently shaded markings arranged in an irregular pattern and (iv) a plurality of circular dots arranged in an irregular pattern;

a control comprising an image processor operable to process image data captured by said first, second and third cameras;

wherein said control stores in memory the respective irregular patterns of said markings of said first, second and third calibration targets;

wherein said control is operable to process image data captured by said cameras that are being calibrated, and wherein, responsive to processing of image data captured by each of said cameras, said control determines a particular local irregular pattern of markings of the respective calibration target viewed by a respective camera;

wherein said control determines, via comparing determined particular local irregular patterns of markings of the respective calibration target to the respective stored in memory irregular patterns of markings of said first, second and third calibration targets, the position of the respective calibration target relative to the respective camera; and

wherein, responsive to processing of captured image data, said calibration system is operable to calibrate said multi-camera vision system.

12. The calibration system of claim 11, wherein said irregular patterned array of markings of said calibration targets comprises irregular pierced dot arrays.

13. The calibration system of claim 11, wherein said irregular patterned array of markings of said calibration targets comprises a plurality of circular dots arranged in an irregular pattern.

14. The calibration system of claim 11, wherein said irregular patterned array of markings of said calibration targets comprises at least one of (i) different colored markings and (ii) different shaded markings.

15. The calibration system of claim 11, wherein, responsive to processing of captured image data, said calibration system is operable to calibrate vision systems of multiple types or sizes of vehicles positioned at said calibration targets.

16. The calibration system of claim 11, comprising a fourth camera disposed at the vehicle and having a fourth field of view forward of the vehicle, wherein a fourth calibration target is disposed at the area at which the vehicle is positioned for the calibrating procedure, and wherein said fourth calibration target is encompassed by said fourth field of view of said fourth camera, and wherein said image processor is operable to process image data captured by said fourth camera, and wherein, responsive to processing of image data captured by said fourth camera, said control is operable to determine a particular local irregular pattern of markings of said fourth calibration target viewed by said fourth camera, and wherein said control determines, via comparing the determined particular local irregular pattern of markings of said fourth calibration target to a stored in memory irregular pattern of markings of said fourth calibration target, the position of said fourth calibration target relative to said fourth camera.

17. A calibration system for a multi-camera vision system of a vehicle, said calibration system comprising:

a first camera disposed at a vehicle and having a first field of view rearward of the vehicle;

a second camera disposed at the vehicle and having a second field of view generally sideward of the vehicle at a driver side of the vehicle;

a third camera disposed at the vehicle and having a third field of view generally sideward of the vehicle at a passenger side of the vehicle;

a fourth camera disposed at the vehicle and having a fourth field of view generally forward of the vehicle;

first, second, third and fourth calibration targets disposed at an area at which the vehicle is positioned for a calibrating procedure;

wherein said first calibration target is encompassed by said first field of view of said first camera;

wherein said second calibration target is encompassed by said second field of view of said second camera;

wherein said third calibration target is encompassed by said third field of view of said third camera;

wherein said fourth calibration target is encompassed by said fourth field of view of said fourth camera;

wherein each of said calibration targets comprises an irregular patterned array of markings, and wherein the pattern of said irregular patterned array of markings is irregular at each of said calibration targets;

wherein said irregular patterned array of markings comprises at least one of (i) a plurality of different colored markings arranged in an irregular color pattern, (ii) a plurality of black and white markings arranged in an irregular pattern, (iii) a plurality of differently shaded markings arranged in an irregular pattern and (iv) a plurality of circular dots arranged in an irregular pattern;

a control comprising an image processor operable to process image data captured by said first, second, third and fourth cameras;

wherein said control stores in memory the respective irregular patterns of said markings of said first, second, third and fourth calibration targets;

wherein said control is operable to process image data captured by said cameras that are being calibrated, and wherein, responsive to processing of image data captured by each of said cameras, said control determines a particular local irregular pattern of markings of the respective calibration target viewed by a respective camera;

wherein said control determines, via comparing determined particular local irregular patterns of markings of the respective calibration target to the respective stored in memory irregular patterns of markings of said first, second, third and fourth calibration targets, the position of the respective calibration target relative to the respective camera; and

wherein, responsive to processing of captured image data, said calibration system is operable to calibrate said multi-camera vision system.

18. The calibration system of claim 17, wherein said irregular patterned array of markings of said calibration targets comprises irregular pierced dot arrays.

19. The calibration system of claim 17, wherein said irregular patterned array of markings comprises at least one of (i) different colored markings and (ii) different shaded markings.

20. The calibration system of claim 17, wherein, responsive to processing of captured image data, said calibration system is operable to calibrate vision systems of multiple types or sizes of vehicles positioned at said calibration targets.