METHOD AND SYSTEM TO PERFORM OPTICAL MOVING OBJECT DETECTION AND TRACKING OVER A WIDE AREA

• US 20100157055A1
• Filed: 08/07/2008
• Published: 06/24/2010
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: Rafael - Armament Development Authority Ltd.
• Original Assignee: Visionmap Ltd. (Government of Israel)
• Inventors: Pechatnikov, Michael
• Granted Patent: US 8,416,298 B2
• Time in Patent Office: Days
• US Class Current: 348/144
• CPC Class Codes: G06T 2207/30181 Earth observation
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/254 involving subtraction of images

Abstract

A method for moving object detection, comprising generating a time series of multi-exposures of scenes, each multi-exposure of a scene comprising a sequence of at least two at least partially overlapping images of that scene captured in rapid succession, wherein the time series of multi-exposures periodically revisits substantially the same scenes, detecting moving objects within each multi-exposure by comparing its sequence of overlapping images, and tracking objects by comparing moving objects detected within multi-exposures of substantially the same scenes.

Claims

1. A method for moving object detection, comprising:

generating a time series of multi-exposures of scenes, each multi-exposure of a scene comprising a sequence of at least two at least partially overlapping images of that scene captured in rapid succession, wherein the time series of multi-exposures periodically revisits substantially the same scenes;

detecting moving objects within each multi-exposure by comparing its sequence of overlapping images; and

tracking objects by comparing moving objects detected within multi-exposures of substantially the same scenes.

2. The method of claim 1 wherein said generating, said detecting is performed within an airborne vehicle, the method further comprising transmitting data characterizing the moving objects from the airborne vehicle to a ground station.

3. The method of claim 2 wherein the data characterizing the moving objects comprises, for each moving object, a capture time, object location coordinates, an object velocity vector, and a thumbnail image of the object.

4. The method of claim 1 wherein the at least two overlapping images of the scene are captured within time intervals of 0.1-0.5 sec.

5. The method of claim 1 wherein the time series of multi-exposures revisits the same scene with a revisit period of at least 5 sec.

6. The method of claim 1 wherein the multi-exposures are double-exposures comprising two respective images captured by two respective cameras.

7. The method of claim 1, wherein said detecting included detecting at least one moving object not suspected to be in said each multi-exposure prior to said detecting.

8. A moving object detection system, comprising:

an airborne segment, comprising;

at least one camera for capturing images of scenes;

a moving object detector coupled with said at least one camera, for receiving as input images of a scene, and for deriving as output information about moving objects detected in the scene and not suspected to be in the scene prior to being detected in the scene; and

an airborne controller coupled with said moving object detector for receiving control commands from a ground segment, and for controlling operation of said moving object detector in response to the received commands;

a ground segment comprising;

an object tracker for receiving as input information about moving objects, and for deriving as output tracking information about the moving objects; and

a ground controller coupled with said object tracker for issuing control commands to said airborne segment, and for receiving information about moving objects from said airborne segment in response to the control commands; and

a communication link for transmitting data between said airborne controller and said ground controller.

9. The moving object detection system of claim 8, wherein said airborne segment further comprises:

an image compressor coupled with said at least one camera, for compressing image data captured by said at least one camera; and

a data storage unit coupled with said image compressor, for storing the compressed images generated by said image compressor.

10. The moving object detection system of claim 8, wherein said at least one camera captures a time series of multi-exposures M₁, M₂, . . . , wherein each multi-exposure M_kf of a scene comprises a sequence,

M_k=(I_k1, I_k2, . . . , I_kmk),

of at least two at least partially overlapping images, I, of that scene, captured in rapid succession, wherein the time series of multi-exposures periodically revisits substantially the same scenes.

11. The moving object detection system of claim 10 wherein said at least one camera captures successive images, I, of a multi-exposure, M, at time intervals of approximately 0.2 sec.

12. The moving object detection system of claim 10 wherein the scenes cover a large ground area, the size of which is controlled via the revisit period.

13. The moving object detection system of claim 8 wherein said communication link has a narrow bandwidth.

14. The moving object detection system of claim 8 wherein said at least one camera has a ground sampling distance in accordance with the sizes of objects that are tracked.

15. The moving object detection system of claim 8 wherein said airborne segment travels at conventional velocities.

16. The moving object detection system of claim 8 wherein said airborne segment travels at conventional altitudes.

17. A moving object detection system, comprising:

an optical unit comprising at least one camera for capturing images of scenes;

an airborne electronics unit comprising;

a controller coupled with said optical unit for controlling fields of view and image capture times of said at least one camera, wherein said controller controls said at least one camera to capture a time series of multi-exposures of scenes, each multi-exposure of a scene comprising a sequence of at least two at least partially overlapping images of that scene captured in rapid succession, wherein the time series of multi-exposures periodically revisits substantially the same scenes; and

a moving object detector coupled with said optical unit for detecting moving objects within each multi-exposure by comparing its sequence of overlapping images; and

a ground processing unit communicatively coupled with said first electronics unit for tracking objects by comparing moving objects detected within multi-exposures of substantially the same scenes.

18. The moving object detection system of claim 17 further comprising an airborne transmitter for transmitting data characterizing the moving objects from the airborne vehicle to the ground station via a communication link.

19. The moving object detection system of claim 18 wherein the data characterizing the moving objects comprises, for each moving object, a capture time, object location coordinates, an object velocity vector, and a thumbnail image of the object.

20. The moving object detection system of claim 18 wherein said airborne transmitter transmits data at low bit rate.

21. The moving object detection system of claim 17 wherein said controller controls said at least one camera so as to capture the at least two overlapping images of the scene within time intervals of 0.1-0.5 sec.

22. The moving object detection system of claim 17 wherein said controller controls said at least one camera so as to revisit the same scene with a period of at least 5 sec.

23. The moving object detection system of claim 17 wherein said at least one camera comprises two cameras, and wherein the multi-exposures are double-exposures comprising two respective images captured by said two respective cameras.

24. The moving object detection system of claim 17 wherein each of said at least one camera is mounted rotatably on a gimbal.

25. The moving object detection system of claim 17 further comprising means for controlling lines-of-sight of said at least one camera.

26. The moving object detection system of claim 17 wherein said moving object detector is for detecting moving objects not suspected to be in said each multi-exposure prior to said detecting.

27. A method for moving object detection, comprising:

generating a time series of multi-exposures of scenes, each multi-exposure of a scene comprising a sequence of at least two at least partially overlapping images of that scene captured in rapid succession, wherein the time series of multi-exposures periodically revisits substantially the same scenes; and

detecting a moving object within each multi-exposure by comparing its sequence of overlapping images, said moving object not suspected to be in said each multi-exposure prior to said detecting.

28. A moving object detection system, comprising:

at least one camera for capturing images of scenes;

a moving object detector coupled with said at least one camera, for receiving as input images of a scene, and for deriving as output information about moving objects detected in the scene and not suspected to be in the scene prior to being detected in the scene; and

an airborne controller coupled with said moving object detector for receiving control commands from a ground segment, and for controlling operation of said moving object detector in response to the received commands.