3D TIME-OF-FLIGHT CAMERA SYSTEM AND POSITION/ORIENTATION CALIBRATION METHOD THEREFOR

• US 20110205340A1
• Filed: 04/27/2009
• Published: 08/25/2011
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Original Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Inventors: Garcia, Frederic, Orsello, Roberto, Solignac, Thomas, Mirbach, Bruno, Grandidier, Frederic
• Granted Patent: US 10,795,006 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4972 Alignment of sensor
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/30196 Human being; Person
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration

Abstract

A camera system comprises a 3D TOF camera for acquiring a camera-perspective range image of a scene and an image processor for processing the range image. The image processor contains a position and orientation calibration routine implemented therein in hardware and/or software, which position and orientation calibration routine, when executed by the image processor, detects one or more planes within a range image acquired by the 3D TOF camera, selects a reference plane among the at least one or more planes detected and computes position and orientation parameters of the 3D TOF camera with respect to the reference plane, such as, e.g., elevation above the reference plane and/or camera roll angle and/or camera pitch angle.

Claims

1-15. -15. (canceled)

16. Position and orientation calibration method for a camera system including a 3D time-of-flight camera, said method comprising

acquiring a camera-perspective range image of a scene using said 3D time-of-flight camera,

detecting one or more planes within said range image and selecting a reference plane among said one or more planes detected,

computing position and orientation parameters of said 3D time-of-flight camera with respect to said reference plane.

17. The method as claimed in claim 16, wherein said position and orientation parameters of said 3D time-of flight camera include at least one of height above said reference plane, camera roll angle and camera pitch angle.

18. The method as claimed in claim 16, wherein said detection of one or more planes within said range image comprises RANSAC-based plane detection.

19. The method as claimed in claim 16, wherein said selecting of a reference plane comprises identifying a floor plane and fixing said floor plane as said reference plane.

20. The method as claimed in claim 19, wherein said selection of said reference plane is effected by said camera based upon and following input of user-defined limits of at least one of camera roll angle and camera pitch angle with respect to said floor plane.

21. The method as claimed in claim 16, wherein said selection of said reference plane comprises presenting said one or more detected planes using a user interface and fixing said reference plane based upon user interaction.

22. The method as claimed in claim 16, comprising

computing coordinate transformation parameters of a coordinate transformation, said coordinate transformation being such that it transforms, when applied to a camera-perspective range image of said scene, such range image into a Cartesian representation of said scene, in which coordinates are defined with respect to said reference plane,

and storing said coordinate transformation parameters within a memory of said camera.

23. The method as claimed in claim 16, wherein said detection of one or more planes comprises at least one of compensating for range errors induced by light spreading in said 3D time-of-flight camera and discarding image pixels containing range information deemed unreliable.

24. A camera system comprising

a 3D time-of-flight camera for acquiring a camera-perspective range image of a scene, and

an image processor for processing said range image,

wherein said image processor comprises a position and orientation calibration routine implemented in at least one of hardware and software, wherein said position and orientation calibration routine, when executed by said image processor, detects one or more planes within a range image acquired by said 3D time-of-flight camera, selects a reference plane among said one or more planes detected and computes position and orientation parameters of said 3D time-of-flight camera with respect to said reference plane.

25. The camera system according to claim 24, wherein said position and orientation parameters comprise at least one of height above said reference plane, camera roll angle and camera pitch angle.

26. The camera system as claimed in any one of claims 24, comprising a user interface for presenting output data to or receiving input data from a user.

27. The camera system as claimed in claim 24, wherein said position and orientation calibration routine, when executed by said image processor, selects said reference plane by identifying a floor plane and fixing said floor plane as said reference plane.

28. The camera system as claimed in claim 26, comprising a user interface for presenting output data to and receiving input data from a user, wherein said calibration routine, when executed by said image processor, selects said reference plane based upon and following input, via said user interface, of user-defined limits of at least one of camera roll angle and camera pitch angle with respect to said floor plane.

29. The camera system as claimed in claim 25, wherein said selection of said reference plane comprises presenting said one or more detected planes using a user interface and fixing said reference plane based upon user interaction.

30. The camera system as claimed in claim 24, comprising a memory, and wherein said calibration routine, when executed by said image processor, computes coordinate transformation parameters of a coordinate transformation from a camera reference system into a world reference system, in which coordinates are defined with respect to said reference plane, and stores said coordinate transformation parameters within said memory.

31. Pedestrian detection system comprising a camera system as claimed in claim 24.

32. A camera system comprising

a 3D time-of-flight camera for acquiring a camera-perspective range image of a scene, and

an image processor for processing said range image,

wherein said image processor is configured to detect one or more planes within a range image acquired by said 3D time-of-flight camera, to select a reference plane among said one or more planes detected and to compute position and orientation parameters of said 3D time-of-flight camera with respect to said reference plane, wherein said camera system comprises a memory,

and wherein said processor is further configured to compute coordinate transformation parameters of a coordinate transformation from a camera reference system into a world reference system, in which coordinates are defined with respect to said reference plane, to store said coordinate transformation parameters within said memory.