VIDEO SPEED DETECTION SYSTEM

• US 20080166023A1
• Filed: 01/07/2008
• Published: 07/10/2008
• Est. Priority Date: 01/05/2007
• Status: Active Grant

• Current Assignee: American Traffic Solutions Incorporated (Verra Mobility Corp.)
• Original Assignee: American Traffic Solutions Incorporated (Verra Mobility Corp.)
• Inventors: WANG, JIGANG
• Granted Patent: US 8,213,685 B2
• Time in Patent Office: Days
• US Class Current: 382/107
• 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: G08G 1/054 photographing overspeeding vehicles

Abstract

A system and method for measuring vehicle speeds using video sensing. The system comprises a tracking camera that generates accurately time-stamped video sequences of the monitored road at high frame rates and a processing unit that analyzes the video sequences in real time to detect moving vehicles and calculate their speeds using the time-over-distance method. The system automatically detects moving vehicles in each image frame and derives vehicle positions from a projective mapping established from reference markers on the road. Time information is obtained from the date and time stamp associated with each image frame. In one example, the system also allows a user of the system to set a trigger speed, and the system automatically saves a video clip of the vehicle whose speed exceeds the trigger speed, recording the speeding vehicle passing through the monitored traffic zone defined by the reference markers.

Claims

1. A system for monitoring vehicles or other objects, comprising:

a tracking camera constructed and arranged to provide a plurality of time-stamped images of a measurement area;

a processing unit, coupled to the tracking camera, that is configured to receive the time stamped images and to process the images to determine from the time-stamped images a speed of a vehicle passing through the measurement area.

2. The system of claim 1, further comprising a high resolution camera coupled to the processing unit that is configured to capture an image of the vehicle in response to a signal from the processing unit.

3. The system of claim 2, wherein the processing unit is configured to print date, time, speed, and a reticule targeted at the vehicle to the image from the high resolution camera.

4. The system of claim 2, wherein the processing unit is configured to receive a trigger speed value from a user of the system.

5. The system of claim 4, wherein the processing unit is configured to compare the speed of the vehicle to the trigger speed and to send a trigger signal to the high resolution camera when the vehicle speed exceeds the trigger speed.

6. The system of claim 4, wherein the system further comprises a storage device, and wherein the processing unit is further configured in combination with the storage device to record the time-stamped images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

7. The system of claim 1, wherein the system further comprising a storage device constructed and arranged to record time-stamped images of the vehicle passing through the measurement area, and wherein the processing unit is further configured to receive the recorded time-stamped images of the vehicle and determine the speed of the vehicle from the recorded time-stamped images.

8. The system of claim 1, wherein the processing unit is further configured to provide a graphical user interface (GUI) to the user of the system.

9. The system of claim 8, wherein the GUI is configured to receive the actual dimension of the measurement area from a user of the system.

10. The system of claim 8, wherein the GUI is configured to provide live video of the measurement area from the tracking camera.

11. The system of claim 10, wherein the processing unit is configured to continuously update the speed of a vehicle and to display the speed of the vehicle at the position of the vehicle in the video.

12. The system of claim 8, wherein the GUI is further configured to display the recorded time stamped images of the vehicle.

13. The system of claim 12, wherein the processing unit is further configured to allow the user of the system to step through the recorded images and determine the frames at which the vehicle passes two reference lines separated with a known distance.

14. The system of claim 13, wherein the processing unit is further configured to determine the speed of the vehicle from the distance between the two reference lines and the difference in the time stamps of the frames at which the vehicle passes the two reference lines.

15. The system of claim 1, wherein the processing unit is further configured to construct rectified images of the measurement area from the plurality of time-stamped images.

16. The system of claim 15, wherein the processor is further configured to construct the rectified images of the measurement area by determining a projective mapping from four point correspondences.

17. The system of claim 1, wherein the processing unit is further configured to map coordinates of at least one of the plurality of time-stamped images to actual coordinates of the measurement area using projective mapping.

18. The system of claim 1, wherein the processing unit is further configured to extract a background image of the measurement area from the plurality of time-stamped images.

19. The system of claim 18, wherein the processing unit is further configured to detect and identify vehicles within the measurement area.

20. The system of claim 19, wherein the processing unit is configured to detect the vehicles by segmenting the rectified image and determining large deviations in the rectified image.

21. The system of the claim 18, wherein the processing unit is configured to extract the background image by temporal median filtering of the plurality of time-stamped images.

22. The system of claim 1, wherein the tracking camera is configured to provide the images at a frequency of at least 15 frames per second.

23. The system of claim 1, wherein the processing unit further comprises an optical character recognition (OCR) component configured to determine the time stamp from each image of the plurality of time-stamped images.

24. The system of claim 1, wherein the processing unit is configured to determine a distance the vehicle has traveled between two time-stamped images.

25. The system of claim 1, wherein the processing unit is configured to continually determine the speed of the vehicle between two time-stamped images as vehicle travels through the measurement area.

26. The system of claim 1, wherein the processing unit is configured to monitor multiple vehicles in the measurement area and measure their speeds simultaneously.

27. The system of claim 1, wherein the processing unit is further configured to collect traffic statistics of the measurement area including any of a number of vehicles passed through and average vehicle speed.

28. A method of traffic monitoring comprising:

collecting a plurality of time-stamped images of a monitored area;

analyzing the plurality of time-stamped images to detect an object moving through the monitored area; and

determining a speed of the object.

29. The method of claim 28, wherein the monitored area includes a section of a road;

and wherein the object is a vehicle.

30. A method of monitoring vehicles or other objects, comprising:

obtaining a plurality of time-stamped images of a measurement area; and

processing the plurality of time-stamped images to determine from the time-stamped images a speed of a vehicle passing through the measurement area.

31. The method of claim 30, further comprising capturing a high resolution image of the vehicle.

32. The method of claim 31, further comprising printing date, time, speed, and a reticule targeted at the vehicle to the high resolution image.

33. The method of claim 31, further comprising receiving an input trigger speed value.

34. The method of claim 33, further comparing the speed of the vehicle to the trigger speed;

and sending a trigger signal to a high resolution camera to obtain the high resolution image when the vehicle speed exceeds the trigger speed.

35. The system of claim 33, further comprising storing the plurality of time-stamped images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

36. The method of claim 30, further comprising receiving recorded time-stamped images of the vehicle;

and determining the speed of the vehicle from the recorded time-stamped images.

37. The method of claim 30, further comprising receiving the actual dimension of the measurement area from a user via a graphical user interface (GUI).

38. The method of claim 30, further comprising displaying live video of the measurement area via a graphical user interface (GUI).

39. The method of claim 38, further comprising continuously updating the speed of a vehicle and displaying the speed of the vehicle at the position of the vehicle in the video.

40. The method of claim 30, further comprising displaying recorded time-stamped images of the vehicle via a graphical user interface (GUI).

41. The method of claim 40, further comprising allowing a user to step through the recorded time-stamped images and determine the frames at which the vehicle passes two reference lines separated by a known distance.

42. The method of claim 41, further comprising determining the speed of the vehicle from the distance between the two reference lines and the difference in the time stamps of the frames at which the vehicle passes the two reference lines.

43. The method of claim 30, further comprising constructing rectified images of the measurement area from the plurality of time-stamped images.

44. The method of claim 43, wherein constructing the rectified images includes determining a projective mapping from four point correspondences.

45. The method of claim 43, further comprising mapping coordinates of at least one of the plurality of time-stamped images to actual coordinates of the measurement area using projective mapping.

46. The method of claim 43, further comprising extracting a background image of the measurement area from the plurality of time-stamped images.

47. The method of claim 43, further comprising detecting and identifying vehicles within the measurement area.

48. The method of claim 47, wherein detecting the vehicles includes segmenting at least one of the rectified images and determining large deviations in the at least one rectified image.

49. The method of the claim 46, wherein extracting the background image includes extracting the background image by temporal median filtering of the plurality of time-stamped images.

50. The method of claim 30, further comprising determining the time stamp from each image of the plurality of time-stamped images using an optical character recognition (OCR) component.

51. The method of claim 30, further comprising determining a distance the vehicle has traveled between two time-stamped images.

52. The method of claim 30, further comprising continually determining the speed of the vehicle between two successive time-stamped images as vehicle travels through the measurement area.

53. The method of claim 30, further comprising monitoring multiple vehicles in the measurement area and measuring their speeds simultaneously.

54. The method of claim 30, further comprising collecting traffic statistics of the measurement area including any of a number of vehicles passed through and average vehicle speed.