Video speed detection system

• US 8,213,685 B2
• Filed: 01/07/2008
• Issued: 07/03/2012
• 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
• Primary Examiner(s): AZARIAN, SEYED H
• Application Number:
  US11/970,371
• Publication Number:
  US 20080166023A1
• Time in Patent Office: 1,639 Days
• Field of Search: 382/103, 382/104, 382/105, 382/106, 382/107, 382/155, 382/168, 382/173, 382/181, 382/193, 382/199, 382/203, 382/209, 382/232, 382/254, 382/260, 382/274, 382/276, 382286-291, 382/305, 382/312, 382/321, 340/933, 340/937, 1/1, 701/35
• 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 compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured; and

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images;

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

provide a GUI to a user of the system, wherein the GUI is configured to present to the user live video of the measurement area from the tracking camera; and

to continuously update the speed of the vehicle and to display the speed of the vehicle at the position of the vehicle in the video.

2. The system of claim 1, further comprising a high resolution camera coupled to the processing unit and 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 further configured to overlay onto the image from the high resolution camera date, time, speed, and a reticule targeted at the vehicle.

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

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

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

7. The system of claim 1, further comprising a storage device constructed and arranged to record the images of the vehicle passing through the measurement area, and wherein the images received by the processing unit are the recorded images of the vehicle.

8. The system of claim 1, wherein the GUI is configured to receive one or more actual dimensions of the measurement area from the user of the system.

9. The system of claim 1, further comprising a storage device constructed and arranged to record the images of the vehicle passing through the measurement area, wherein the images received by the processing unit are the recorded images of the vehicle, and wherein the GUI is further configured to display the recorded images of the vehicle.

10. The system of claim 9, 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 by a known distance.

11. The system of claim 10, wherein the processing unit is further configured to calculate the speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

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

13. The system of claim 12, wherein the processing unit is further configured to construct the rectified images of the measurement area by determining a projective mapping from four point correspondences.

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

15. 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 images.

16. The system of the claim 15, wherein the processing unit is configured to extract the background image by temporal median filtering of the plurality of images.

17. The system of claim 1, wherein the processing unit is configured to detect vehicles in the plurality of images by segmenting rectified images and determining large deviations in the rectified images.

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

19. 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 the vehicle travels through the measurement area.

20. The system of claim 1, wherein the processing unit is configured to monitor multiple vehicles in the measurement area and to calculate their speeds concurrently.

21. The system of claim 1, wherein the processing unit is further configured to collect traffic statistics of the measurement area including one or more of statistics selected from the group consisting of number of vehicles passed through and average vehicle speed.

22. The system of claim 1, wherein the timing information associated with each of the images is overlaid onto its respective image, thereby forming time-stamped images.

23. The system of claim 22, wherein the processing unit further comprises an optical character recognition component configured to determine a time stamp from one or more of the plurality of time-stamped images.

24. The system of claim 1, wherein the processing unit is configured to calculate the speed of the vehicle by:

making a distance determination of how far the vehicle has traveled between two real-world positions;

making a time determination, based on the accessed timing information, of how much time has elapsed between the two images used to make the distance determination; and

dividing the distance determination by the time determination to yield the calculated speed of the vehicle.

25. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

displaying the plurality of images of a measurement area as live video via a graphical user interface; and

continuously updating the speed of a vehicle and displaying the speed of the vehicle at the position of the vehicle in the video.

26. The method of claim 25, further comprising:

capturing a high resolution image of the vehicle.

27. The method of claim 26, further comprising:

overlaying on the high resolution image date, time, speed, and a reticule targeted at the vehicle.

28. The method of claim 26, further comprising:

receiving an input trigger speed value.

29. The method of claim 28, further comprising:

comparing the calculated 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 calculated speed of the vehicle exceeds the trigger speed.

30. The system of claim 28, further comprising:

storing the plurality of images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

31. The method of claim 25, wherein capturing a plurality of images of a measurement area comprising receiving recorded images of the measurement area.

32. The method of claim 25, further comprising:

receiving an actual dimension of the measurement area from a user via a graphical user interface.

33. The method of claim 25, wherein the plurality of images of the measurement area are recorded images, and the method further comprises displaying the recorded images via a graphical user interface.

34. The method of claim 33, further comprising:

allowing a user to step through the recorded images and to determine frames at which the vehicle passes two reference lines separated by a known distance.

35. The method of claim 34, further comprising:

determining the calculated speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

36. The method of claim 25, further comprising:

constructing rectified images of the measurement area from the plurality of images.

37. The method of claim 36, wherein constructing the rectified images comprises determining a projective mapping from four point correspondences.

38. The method of claim 36, further comprising:

mapping coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

39. The method of claim 36, further comprising:

extracting a background image of the measurement area from the plurality of images.

40. The method of the claim 39, wherein extracting the background image includes extracting the background image by temporal median filtering of the plurality of images.

41. The method of claim 36, wherein detecting the vehicles comprises segmenting at least one of the rectified images and determining large deviations in the at least one rectified image.

42. The method of claim 25, further comprising:

determining the time stamp from each image of the plurality of time-stamped images via optical character recognition.

43. The method of claim 25, further comprising:

continually calculating the calculated speed of the vehicle between two successive images as the vehicle travels through the measurement area.

44. The method of claim 25, further comprising:

repeating the detecting, making a distance determination, making a time determination, and calculating a speed steps for multiple vehicles in the measurement area, thereby calculating their speeds concurrently.

45. The method of claim 25, further comprising:

collecting traffic statistics of the measurement area including one or more of statistics selected from the group consisting of number of vehicles passed through and average vehicle speed.

46. The method of claim 25, wherein calculating the speed of the vehicle comprises:

making a distance determination of how far the vehicle has traveled between two real-world positions;

making a time determination of how much time has elapsed between the two images used to make the distance determination; and

dividing the distance determination by the time determination to yield the speed.

47. The method of claim 25, further comprising:

overlaying onto each image the timing information associated with that image, thereby forming time-stamped images.

48. The method of claim 25, further comprising:

causing a citation to be issued for the vehicle'"'"'s exceeding the speed limit.

49. A system for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images;

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

provide a GUI to a user of the system; and

a storage device constructed and arranged to record the images of the vehicle passing through the measurement area, wherein the images received by the processing unit are the recorded images of the vehicle, wherein the GUI is further configured to display the recorded images of the vehicle, and 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 by a known distance.

50. The system of claim 49, wherein the processing unit is further configured to calculate the speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

51. A system for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured; and

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images;

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

construct rectified images of the measurement area from the plurality of images by determining a projective mapping from four point correspondences.

52. A system for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured; and

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images;

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

map coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

53. A system for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured; and

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images;

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

extract a background image of the measurement area from the plurality of images by temporal median filtering of the plurality of images.

54. A system for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the system comprising:

a tracking camera constructed and arranged to provide a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured; and

a processing unit, coupled to the tracking camera, configured to;

receive the images from the tracking camera;

detect in the images a vehicle moving through the measurement area;

determine a real-world position of the vehicle relative to the roadway for each of at least two of the images;

access the timing information associated with said at least two of the images; and

calculate a speed of the vehicle based on the real-world positions and accessed timing information, wherein the real-world positions and accessed timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit, wherein the processing unit is configured to calculate the speed of the vehicle by;

making a distance determination of how far the vehicle has traveled between two real-world positions;

making a time determination, based on the accessed timing information, of how much time has elapsed between the two images used to make the distance determination; and

dividing the distance determination by the time determination to yield the calculated speed of the vehicle.

55. The system of claim 54, further comprising a high resolution camera coupled to the processing unit and configured to capture an image of the vehicle in response to a signal from the processing unit.

56. The system of claim 55, wherein the processing unit is further configured to overlay onto the image from the high resolution camera date, time, speed, and a reticule targeted at the vehicle.

57. The system of claim 55, wherein the processing unit is further configured to receive a trigger speed value from a user of the system.

58. The system of claim 57, wherein the processing unit is further configured to compare the calculated speed of the vehicle to the trigger speed and to send a trigger signal to the high resolution camera when the calculated speed of the vehicle exceeds the trigger speed.

59. The system of claim 57, further comprising a storage device, and wherein the processing unit is further configured in combination with the storage device to record the images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

60. The system of claim 54, further comprising a storage device constructed and arranged to record the images of the vehicle passing through the measurement area, and wherein the images received by the processing unit are the recorded images of the vehicle.

61. The system of claim 54, wherein the processing unit is further configured to provide a GUI to a user of the system.

62. The system of claim 61, wherein the GUI is configured to receive one or more actual dimensions of the measurement area from the user of the system.

63. The system of claim 61, wherein the GUI is further configured to present to the user live video of the measurement area from the tracking camera.

64. The system of claim 63, wherein the processing unit is further configured to continuously update the speed of the vehicle and to display the speed of the vehicle at the position of the vehicle in the video.

65. The system of claim 61, further comprising a storage device constructed and arranged to record the images of the vehicle passing through the measurement area, wherein the images received by the processing unit are the recorded images of the vehicle, and wherein the GUI is further configured to display the recorded images of the vehicle.

66. The system of claim 65, 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 by a known distance.

67. The system of claim 66, wherein the processing unit is further configured to the speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

68. The system of claim 54, wherein the processing unit is further configured to construct rectified images of the measurement area from the plurality of images.

69. The system of claim 68, wherein the processing unit is further configured to construct the rectified images of the measurement area by determining a projective mapping from four point correspondences.

70. The system of claim 54, wherein the processing unit is further configured to map coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

71. The system of claim 54, wherein the processing unit is further configured to extract a background image of the measurement area from the plurality of images.

72. The system of the claim 71, wherein the processing unit is configured to extract the background image by temporal median filtering of the plurality of images.

73. The system of claim 54, wherein the processing unit is configured to detect vehicles in the plurality of images by segmenting rectified images and determining large deviations in the rectified images.

74. The system of claim 54, wherein the tracking camera is configured to provide the plurality of images at a frequency of at least 15 frames per second.

75. The system of claim 54, wherein the processing unit is configured to continually determine the speed of the vehicle between two time-stamped images as the vehicle travels through the measurement area.

76. The system of claim 54, wherein the processing unit is configured to monitor multiple vehicles in the measurement area and to calculate their speeds concurrently.

77. The system of claim 54, wherein the processing unit is further configured to collect traffic statistics of the measurement area including one or more of statistics selected.

78. The system of claim 54, wherein the timing information associated with each of the images is overlaid onto its respective image, thereby forming time-stamped images.

79. The system of claim 78, wherein the processing unit further comprises an optical character recognition component configured to determine a time stamp from one or more of the plurality of time-stamped images.

80. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein the plurality of images of the measurement area are recorded images, and wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

displaying the recorded images via a graphical user interface; and

allowing a user to step through the recorded images and to determine frames at which the vehicle passes two reference lines separated by a known distance.

81. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein the plurality of images of the measurement area are recorded images, and wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

displaying the recorded images via a graphical user interface; and

determining the calculated speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

82. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

constructing rectified images of the measurement area from the plurality of image, wherein constructing the rectified images comprises determining a projective mapping from four point correspondences.

83. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

constructing rectified images of the measurement area from the plurality of images; and

mapping coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

84. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit;

constructing rectified images of the measurement area from the plurality of images; and

extracting a background image of the measurement area from the plurality of images, wherein extracting the background image includes extracting the background image by temporal median filtering of the plurality of images.

85. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images;

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit; and

repeating the detecting, making a distance determination, making a time determination, and calculating a speed steps for multiple vehicles in the measurement area, thereby calculating their speeds concurrently.

86. The method of claim 85, further comprising:

capturing a high resolution image of the vehicle.

87. The method of claim 86, further comprising:

overlaying on the high resolution image date, time, speed, and a reticule targeted at the vehicle.

88. The method of claim 86, further comprising:

receiving an input trigger speed value.

89. The method of claim 88, further comprising:

comparing the calculated 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 calculated speed of the vehicle exceeds the trigger speed.

90. The system of claim 88, further comprising:

storing the plurality of images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

91. The method of claim 85, wherein capturing a plurality of images of a measurement area comprising receiving recorded images of the measurement area.

92. The method of claim 85, further comprising:

receiving an actual dimension of the measurement area from a user via a graphical user interface.

93. The method of claim 85, further comprising:

displaying the plurality of images of a measurement area as live video via a graphical user interface.

94. The method of claim 93, 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.

95. The method of claim 85, wherein the plurality of images of the measurement area are recorded images, and the method further comprises displaying the recorded images via a graphical user interface.

96. The method of claim 95, further comprising:

allowing a user to step through the recorded images and to determine frames at which the vehicle passes two reference lines separated by a known distance.

97. The method of claim 95, further comprising:

determining the calculated speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

98. The method of claim 85, further comprising:

constructing rectified images of the measurement area from the plurality of images.

99. The method of claim 98, wherein constructing the rectified images comprises determining a projective mapping from four point correspondences.

100. The method of claim 98, further comprising:

mapping coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

101. The method of claim 98, further comprising:

extracting a background image of the measurement area from the plurality of images.

102. The method of the claim 101, wherein extracting the background image includes extracting the background image by temporal median filtering of the plurality of images.

103. The method of claim 101, wherein detecting the vehicles comprises segmenting at least one of the rectified images and determining large deviations in the at least one rectified image.

104. The method of claim 85, further comprising:

determining the time stamp from each image of the plurality of time-stamped images via optical character recognition.

105. The method of claim 85, further comprising:

continually calculating the calculated speed of the vehicle between two successive images as the vehicle travels through the measurement area.

106. The method of claim 85, further comprising:

collecting traffic statistics of the measurement area including one or more of statistics selected from the group consisting of number of vehicles passed through and average vehicle speed.

107. The method of claim 85, wherein calculating the speed of the vehicle comprises:

making a distance determination of how far the vehicle has traveled between two real-world positions;

making a time determination of how much time has elapsed between the two images used to make the distance determination; and

dividing the distance determination by the time determination to yield the speed.

108. The method of claim 85, further comprising:

overlaying onto each image the timing information associated with that image, thereby forming time-stamped images.

109. The method of claim 85, further comprising:

causing a citation to be issued for the vehicle'"'"'s exceeding the speed limit.

110. A method for monitoring compliance of moving vehicles on a roadway subject to a speed limit, the method comprising:

capturing a plurality of images of a measurement area on the roadway, wherein each of the images is associated with timing information indicating when the image was captured;

detecting in the images a vehicle moving through the measurement area;

determining, based on the images, a real-world position of the vehicle relative to the roadway for each of at least two of the images; and

calculating a speed of the vehicle based on the real-world positions and timing information associated with the corresponding images, wherein the real-world positions and timing information are sufficiently accurate for the calculated speed to be used to determine whether the vehicle should be issued a citation for exceeding the speed limit, wherein calculating the speed of the vehicle comprises;

making a distance determination of how far the vehicle has traveled between two real-world positions;

making a time determination of how much time has elapsed between the two images used to make the distance determination; and

dividing the distance determination by the time determination to yield the speed.

111. The method of claim 110, further comprising:

capturing a high resolution image of the vehicle.

112. The method of claim 111, further comprising:

overlaying on the high resolution image date, time, speed, and a reticule targeted at the vehicle.

113. The method of claim 111, further comprising:

receiving an input trigger speed value.

114. The method of claim 113, further comprising:

comparing the calculated 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 calculated speed of the vehicle exceeds the trigger speed.

115. The system of claim 113, further comprising:

storing the plurality of images of a vehicle whose speed exceeds the trigger speed as the vehicle travels though the measurement area.

116. The method of claim 110, wherein capturing a plurality of images of a measurement area comprising receiving recorded images of the measurement area.

117. The method of claim 110, further comprising:

receiving an actual dimension of the measurement area from a user via a graphical user interface.

118. The method of claim 110, further comprising:

displaying the plurality of images of a measurement area as live video via a graphical user interface.

119. The method of claim 118, 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.

120. The method of claim 110, wherein the plurality of images of the measurement area are recorded images, and the method further comprises displaying the recorded images via a graphical user interface.

121. The method of claim 120, further comprising:

allowing a user to step through the recorded images and to determine frames at which the vehicle passes two reference lines separated by a known distance.

122. The method of claim 120, further comprising:

determining the calculated speed of the vehicle from the distance between the two reference lines and the difference in the timing information associated with the frames at which the vehicle passes the two reference lines.

123. The method of claim 110, further comprising:

constructing rectified images of the measurement area from the plurality of images.

124. The method of claim 123, wherein constructing the rectified images comprises determining a projective mapping from four point correspondences.

125. The method of claim 123, further comprising:

mapping coordinates of at least one of the plurality of images to actual coordinates of the measurement area using projective mapping.

126. The method of claim 123, further comprising:

extracting a background image of the measurement area from the plurality of images.

127. The method of claim 126, wherein detecting the vehicles comprises segmenting at least one of the rectified images and determining large deviations in the at least one rectified image.

128. The method of the claim 123, wherein extracting the background image includes extracting the background image by temporal median filtering of the plurality of images.

129. The method of claim 110, further comprising:

determining the time stamp from each image of the plurality of time-stamped images via optical character recognition.

130. The method of claim 110, further comprising:

continually calculating the calculated speed of the vehicle between two successive images as the vehicle travels through the measurement area.

131. The method of claim 110, further comprising:

repeating the detecting, making a distance determination, making a time determination, and calculating a speed steps for multiple vehicles in the measurement area, thereby calculating their speeds concurrently.

132. The method of claim 110, further comprising:

collecting traffic statistics of the measurement area including one or more of statistics selected from the group consisting of number of vehicles passed through and average vehicle speed.

133. The method of claim 110, further comprising:

overlaying onto each image the timing information associated with that image, thereby forming time-stamped images.

134. The method of claim 110, further comprising:

causing a citation to be issued for the vehicle'"'"'s exceeding the speed limit.