Method and apparatus for external calibration of a camera via a graphical user interface

• US 7,151,562 B1
• Filed: 08/03/2000
• Issued: 12/19/2006
• Est. Priority Date: 08/03/2000
• Status: Active Grant

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Trajkovic, Miroslav
• Primary Examiner(s): NGUYEN, LUONG TRUNG
• Application Number:
  US09/634,731
• Time in Patent Office: 2,329 Days
• Field of Search: 348/211.8, 348/211.13, 348/211.14, 348/211.99, 348/207.1, 348/157, 348/143, 702/85, 702/94, 702/150, 702/152, 702/153, 382/106
• US Class Current: 348/211.13
• 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 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

A camera of a camera-based image processing system is calibrated using a graphical user interface (GUI) of the system. A representation of an area in which the camera is to be operated is presented via the GUI, and calibration information is obtained for each of a set of one or more calibration points sequentially as the camera is pointed to corresponding positions in the area. For each of the one or more calibration points, the calibration information is obtained after a command is entered identifying a corresponding position of the calibration point within the representation of the area as presented via the GUI. An external calibration including camera position and orientation is then computed for the camera based on the calibration information obtained for the one or more calibration points.

Claims

1. A method for calibrating a camera of a camera-based image processing system, the method comprising the steps of:

presenting via a graphical user interface a representation of an area in which the camera is to be operated;

selecting at least one calibration point presented in the representation;

obtaining, responsively to said selecting, calibration information for each selected point sequentially as the camera is pointed to corresponding positions in the area, wherein, in case of more than one calibration point, the pointing to any next one of said corresponding positions amounts to rotating, in place, around a pan axis of the camera, a tilt axis of the camera or both axes;

entering, for said each selected point, a command identifying a corresponding position of the selected point within said representation; and

computing at least one of position and orientation information for the camera based on the obtained calibration information.

2. The method of claim 1, wherein said at least one calibration point comprises a single calibration point and the computed information comprises a pan bias for the camera.

4. The method of claim 1, wherein said at least one calibration point constitute a set comprised of at least three calibration points, and the computed information comprises a tilt bias of the camera.

5. The method of claim 1 wherein a user points the camera to a position of said corresponding positions by adjusting at least one of a pan setting, a tilt setting and a zoom setting of the camera.

6. The method of claim 1 wherein the obtaining step is carried out for said corresponding position upon receipt of the command.

7. The method of claim 1 wherein the area in which the camera is to be operated comprises a room, at least a portion of which is monitored by the camera.

8. The method of claim 1 wherein the orientation information comprises at least one of a pan bias and a tilt bias.

9. The method of claim 1 wherein the computing step computes a pan bias for the camera using the calibration information and assuming that the camera position is known and the tilt bias is zero.

10. The method of claim 1 wherein the computing step computes a camera position and a pan bias for the camera using the calibration information and assuming that a camera height is known and the tilt bias is zero.

11. The method of claim 1 wherein the computing step computes a tilt bias for the camera after first determining a camera position and a pan bias for the camera.

3. A method for calibrating a camera of a camera-based image processing system, the method comprising the steps of:

presenting via a graphical user interface a representation of an area in which the camera is to be operated;

obtaining calibration information for each of at least three calibration points sequentially as the camera is pointed to the corresponding positions in the area, wherein the pointing to any next one of said corresponding positions amounts to rotating, in place, around a pan axis of the camera, a tilt axis of the camera or both axes and, for each of the calibration points, a command is entered identifying a corresponding position of the calibration point within the representation of the area as presented via the graphical user interface; and

computing at least one of position and orientation information for the camera based on the calibration information obtained for the calibration points, wherein the computer information comprises a two-dimensional position of the camera and a pan bias of the camera.

12. An apparatus for use in calibrating a camera of a camera-based image processing system, the apparatus comprising:

a processor operative;

(i) to present via a graphical user interface a representation of an area in which the camera is to be operated;

(ii) to select at least one calibration point presented in the representation;

(iii) to obtain, responsively to said selecting, calibration information for each selected point sequentially as the camera is pointed to corresponding positions in the area, wherein, in case of more than one calibration point, the pointing to any next one of said corresponding positions amounts to rotating, in place, around a pan axis of the camera, a tilt axis of the camera or both axes and, to enter, for each said selected point, a command identifying a corresponding position of the selected point within said representation; and

(iv) to compute at least one of position and orientation information for the camera based on the obtained calibration information; and

a memory coupled to the processor and operative to store at least a portion of the obtained calibration information.

13. The apparatus of claim 12 wherein said at least one calibration point comprises a single calibration point and the computed information comprises a pan bias for the camera.

14. The apparatus of claim 12, wherein said at least one calibration point constitute a set comprised of at least three calibration points, and the computed information comprises a two-dimensional position of the camera and a pan bias of the camera.

15. The apparatus of claim 12 wherein said at least one calibration point constitute a set comprised of at least three calibration points, and the computed information comprises a tilt bias of the camera.

16. The apparatus of claim 12 wherein a user points the camera to a position in the area corresponding to a given one of the calibration points by adjusting at least one of a pan setting, a tilt setting and a zoom setting of the camera.

17. The apparatus of claim 12 wherein the respective calibration information is obtained for said corresponding position upon receipt of the command.

18. The apparatus of claim 12 wherein the area in which the camera is to be operated comprises a room, at least a portion of which is monitored by the camera.

19. The apparatus of claim 12 wherein the orientation information comprises at least one of a pan bias and a tilt bias.

20. The apparatus of claim 12 wherein the processor is further operative to compute a pan bias for the camera using the calibration information and assuming that the camera position is known and the tilt bias is zero.

21. The apparatus of claim 12, wherein the processor is further operative to compute a camera position and a pan bias for the camera using the calibration information and assuming that a camera height is known and the tilt bias is zero.

22. The apparatus of claim 12, wherein the processor is further operative to compute a tilt bias for the camera after first determining a camera position and a pan bias for the camera.

23. An article of manufacture comprising a storage medium for storing one or more programs for use in calibrating a camera of a camera-based image processing system, wherein the one or more programs when read and executed by a processor implement the steps of:

presenting via a graphical user interface a representation of an area in which the camera is to be operated;

selecting at least one calibration point presented in the representation;

obtaining, responsively to said selecting, calibration information for each selected point sequentially as the camera is pointed to corresponding positions in the area, wherein, in case of more than one calibration point, the pointing to any next one of said corresponding positions amounts to rotating, in place, around a pan axis of the camera, a tilt axis of the camera or both axes;

entering, for said each selected point, a command identifying a corresponding position of the selected point within said representation; and

computing at least one of position and orientation information for the camera based on the obtained calibration information.