Vehicle speed assessment system and method

• US 20090046897A1
• Filed: 04/09/2008
• Published: 02/19/2009
• Est. Priority Date: 04/16/2007
• Status: Active Grant

• Current Assignee: Redflex Traffic Systems Inc.
• Original Assignee: Redflex Traffic Systems Inc.
• Inventors: Mardesic, Sime, Rowsell, Andrew
• Granted Patent: US 8,712,105 B2
• Time in Patent Office: Days
• US Class Current: 382/107
• CPC Class Codes: G06V 20/54 of traffic, e.g. cars on the road, trains or boats
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: G08G 1/054 photographing overspeeding vehicles

Abstract

A method of assessing the speed of a vehicle including the steps of obtaining a first image of a vehicle; obtaining a second image of the vehicle captured at a known time after capture of the first image; selecting a reference point on the vehicle in the first image; and indicating a location in the second image corresponding to a predicted location of the selected vehicle reference point assuming that the vehicle travels at a particular speed between the times of capture of the first and second images.

Claims

1. A method of assessing the speed of a vehicle including the steps of:

obtaining a first image of a vehicle;

obtaining a second image of the vehicle captured at a known time after capture of the first image;

selecting a reference point on the vehicle in the first image; and

indicating a location in the second image corresponding to a predicted location of the selected vehicle reference point assuming that the vehicle travels at a particular speed between the times of capture of the first and second images.

2. The method of claim 1, wherein said first image is displayed to an operator, and wherein said operator selects said vehicle reference point.

3. The method of claim 1, wherein said second image is displayed to an operator, and said operator visually determines whether or not said predicted location indicated on said second image matches an actual location of said vehicle reference point in said second image.

4. The method of claim 1, wherein said predicted location is indicated by a line in the second image.

5. The method of claim 1, including the step of detecting a speed of said vehicle in said first image, and wherein said predicted location is determined assuming that said vehicle is travelling at said detected speed.

6. The method of claim 1, wherein said predicted location is determined assuming that said vehicle is travelling at a fixed speed.

7. The method of claim 1, including the step of indicating a tolerance region in the second image around said predicted location.

8. The method of claim 1, including the step of providing tolerance markers in said second image about said predicted location.

9. The method of claim 1, wherein said reference point is a point of contact of said vehicle with a road surface.

10. The method of claim 1, including the step of determining a perspective transform for mapping real world location points in an imaged enforcement site with pixel locations in an image of said site.

11. The method of claim 1, including identifying calibration markers having known distance relationships in an imaged scene, determining pixel locations in an image of the scene that correspond to said calibration markers, and determining a perspective transform between real world locations of said calibration markers in said imaged scene and said pixel locations.

12. The method of claim 1, including determining whether or not a calibration verification feature of an imaged scene is at an expected pixel location in the corresponding image of the scene.

13. The method of claim 1, including the step of enlarging a portion of an image about a point on the image that is to be selected or that is to be matched.

14. The method of claim 1, including the step of providing a composite image including said vehicle both in a first position corresponding to said vehicle'"'"'s position in said first image and in a second position corresponding to said vehicle'"'"'s position in said second image.

15. The method of claim 1, wherein vehicle images are obtained from a still camera.

16. The method of claim 1, wherein vehicle images are obtained from frames of a video camera.

17. The method of claim 1, including the step of obtaining one or more further images of said vehicle, and of indicating in each image a predicted location of the selected vehicle reference point.

18. The method of claim 1, wherein a plurality of predicted locations of said vehicle reference point are indicated on an image, each of said predicted locations corresponding to a different vehicle speed.

19. The method of claim 1, wherein a marker corresponding to predicted locations of said vehicle reference point is movable in said image.

20. Vehicle speed assessment apparatus including:

means for obtaining first and second images of a vehicle, said second image being captured a known time after said first image is captured;

data processing means for noting a selected reference vehicle point in said first image, and for determining a location in said second image corresponding to a predicted location of the selected reference point assuming that said vehicle travels at a particular speed in the time period between the capturing of said first and second images.

21. The apparatus of claim 20, including display means for displaying said first image to an operator, and input means for allowing an operator to select said vehicle reference point.

22. The apparatus of claim 20, including display means for displaying said second image to an operator, and input means for allowing an operator to indicate whether or not an actual location of said selected vehicle reference point matches said predicted location.

23. The apparatus of claim 20, include vehicle speed detection means for detecting a speed of a vehicle, and wherein said particular speed is a detected speed of said vehicle.

24. The apparatus of claim 20, wherein said particular speed is a speed limit associated with said first and second images.

25. A software product including:

a component for obtaining a first image of a vehicle;

a component for obtaining a second image of the vehicle captured a known time after capture of the first image;

a component for selecting a vehicle reference point in the first image; and

a component for indicating a location in the second image corresponding to a predicted location of the selected vehicle reference point assuming that the vehicle travels at a particular speed between the times when the first and second images are captured.

26. A method of verifying the speed of a vehicle determined by a primary vehicle detection speed system, the method including the steps of:

determining a primary speed assessment of a vehicle using a primary vehicle speed assessment method;

determining whether said vehicle has violated a speed limit using said primary speed assessment;

obtaining a first image of said vehicle that is determined to have violated said speed limit;

obtaining a second image of said vehicle, said second image being captured a known time after the capture of said first image;

selecting a vehicle reference point in said first image;

indicating in said second image an expected position of said selected vehicle reference point assuming that said vehicle travels at said primary speed assessment between capture times of said first and second images; and

determining whether an actual location of said vehicle reference point in said second image corresponds with said expected location of the vehicle reference point.

27. A method of assessing the speed of a vehicle, the method including the steps of:

obtaining a first image of a vehicle;

obtaining a second image of said vehicle captured a known time after said first image is captured;

selecting a vehicle reference point in said first image;

indicating in said second image a plurality of speed markers, each corresponding to a predicted location of said selected vehicle reference point assuming that said vehicle travels at a particular speed between capture times associated with said first and second images; and

determining a speed for said vehicle based on a comparison of an actual location of said selected vehicle reference point in said second image with said speed markers.

28. A method of assessing vehicle speed, the method including the steps of:

obtaining a first image of a vehicle;

obtaining a second image of said vehicle captured a known time after the capture of said first image;

noting the selecting of a vehicle reference point in said first image;

displaying a movable marker in said second image corresponding to a predicted location of said selected vehicle reference point assuming that said vehicle travels at a particular speed;

monitoring movement of said marker in the second image; and

determining a speed associated with said marker based on a location of said marker in said second image.

29. A method of assessing vehicle speed, the method including the steps of:

obtaining a first image of a vehicle;

obtaining further images of said vehicle known times after said first image;

selecting a vehicle reference point in said first image;

placing in said further images a marker corresponding to a predicted location of said selected vehicle reference point in said further images assuming that said vehicle travels at a particular speed between said images; and

monitoring whether said markers track said selected vehicle reference point in said further images.

30. A traffic violation image, a set of images, or video sequence showing a vehicle on a roadway, a vehicle reference point and a predicted location for the vehicle reference point assuming a particular vehicle speed.

31. A traffic violation notice including an image, a set of images or video sequence of claim 30.