Semi-Automatic Relative Calibration Method for Master Slave Camera Control

• US 20100141767A1
• Filed: 12/10/2008
• Published: 06/10/2010
• Est. Priority Date: 12/10/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wilson, Jeremy Craig, Mohanty, Kamini Kanta, Gellaboina, Mahesh Kumar
• Granted Patent: US 8,488,001 B2
• Time in Patent Office: Days
• US Class Current: 348/159
• CPC Class Codes: G08B 13/19643 wherein the cameras play different roles, e.g. different resolution, different camera type, master-slave camera
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

A method for capturing surveillance images includes of a secured area has a first camera with a first field of view and a second camera with a second field of view. An optical center is determined for the second field of view. A magnification ratio is determined between a target located in the first field of view relative to the second field of view. A pan and tilt model is determined that provides a relationship between a first camera coordinates and pan and tilt values to position the second camera at the optical center. A target is captured in the first field of view and the second camera is controlled to record the target in the second field of view with the second field of view being an enhanced view relative to the first field of view.

Claims

1. A method comprising:

providing a first camera with a first field of view;

providing a second camera with a second field of view;

determining an optical center for the second field of view;

determining a magnification ratio between a target located in the first field of view relative to the second field of view;

determining a pan and tilt model that provides a relationship between a first camera coordinates and pan and tilt values to position the second camera at the optical center;

capturing the target in the first field of view; and

controlling the second camera to record the target in the second field of view with the second field of view being an enhanced view relative to the first field of view.

2. The method of claim 1, wherein the enhanced view is a magnified view of the target.

3. The method of claim 1, wherein the first field of view is a wider field of view relative to the second field of view.

4. The method of claim 1, wherein the second camera is a pan, tilt, zoom camera.

5. The method of claim 1, further comprising controlling the second camera to record the target by receiving a magnified value, a pan adjustment value and a tilt adjustment value from the first camera.

6. The method of claim 1, further comprising determining the optical center by an intersection of optical vectors formed by a first bounding box drawn over the target at a first magnification and by a second bounding box drawn over the target at a second magnification level.

7. The method of claim 1, wherein the first camera and the second camera operate in a master-slave arrangement where at least one of the first and the second camera controls at least one parameter of the other camera.

8. The method of claim 1, further comprising providing a single PTZ camera to perform functions for both the first and the second cameras.

9. The method of claim 1, further comprising determining the magnification ratio between the target located in the first field of view relative to the second field of view by:

capturing an image with the first camera in the first field of view;

capturing the image with the second camera in the second field of view;

providing a first input associated with the image in the first field of view; and

providing a second input with the image in the second field of view;

magnifying the image in the second field of view; and

correlating the first and the second inputs to form the magnification ratio.

10. The method of claim 9, wherein the first input comprises drawing a first bounding box around the target in the first field of view using a graphical interface.

11. The method of claim 10, wherein the second input comprises drawing a second bounding box around the target in the second field of view using the graphical interface.

12. The method of claim 9, wherein the magnification ratio provides at least a height and a width of the image for a plurality of magnification steps.

13. The method of claim 1, further comprising determining the pan and tilt model that provides the relationship between the first camera coordinates and the pan and tilt values to position the second camera at the optical center by:

panning and tilting the second camera to position the target at a second optical center; and

incrementally panning the second camera by a predetermined amount between at least two directions and measuring a displacement of the target in the second field of view.

14. The method of claim 13, further comprising determining the pan and tilt model by:

incrementally tilting the second camera by a predetermined amount between at least two directions and measuring a displacement of the target in the second field of view.

15. The method of claim 14, further comprising determining the pan and tilt model by:

determining a horizontal and a vertical gradient as a function of pan and tilt.

16. The method of claim 15, further comprising converting the target coordinates received by the first camera using the pan and tilt model to a second format for the second camera having the second field of view;

the second format including pan, tilt, and zoom parameters for the target image to provide the enhanced image.

17. The method of claim 13, further comprising incrementally panning the second camera by at least one degree between at least two directions and measuring the displacement of the target in the second field of view.

18. The method of claim 14, further comprising incrementally tilting the second camera by at least one degree between at least two directions and measuring the displacement of the target in the second field of view.

19. A security system comprising:

a first camera recording a first field of view;

a second camera including a panning function, a tilting function, and a magnification function recording a second field of view;

the first camera recording a target in the first field of view, and outputting a control signal to a computing device indicative of a location parameter of the target in the fixed field of view;

the computing device receiving the control signal and converting the control signal to a second signal;

the second camera receiving the second signal and engaging in at least one function including the panning function, the tilting function, and the zooming function to record the target in the second field of view in response to the second signal;

the second camera being calibrated to the first camera by a model that includes at least one of (a) an optical center for the second field of view, (b) a magnification ratio between the target located in the first field of view relative to the second field of view and (c) a pan and tilt model that provides a relationship between a first camera coordinates and pan and tilt values to position the second camera at the optical center. 24