Vehicle speed verification system and method

• US 8,712,105 B2
• Filed: 04/09/2008
• Issued: 04/29/2014
• Est. Priority Date: 04/16/2007
• Status: Active Grant

• Current Assignee: Redflex Traffic Systems Inc.
• Original Assignee: Redflex Traffic Systems Inc.
• Inventors: Rowsell, Andrew, Mardesic, Sime
• Primary Examiner(s): Akhavannik, Hadi
• Assistant Examiner(s): RASHIDIAN, MOHAMMAD M
• Application Number:
  US12/081,010
• Publication Number:
  US 20090046897A1
• Time in Patent Office: 2,211 Days
• Field of Search: 382/100, 382/107, 382/105, 382103-104, 340/917, 340/933, 340/937, 348/145, 348/154, 356/27, 701/93
• 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 verifying speed of a vehicle to provide independent verification of speed detected by a primary speed assessment system, said primary speed assessment system using a primary speed detector to detect speed of said vehicle, said method using a secondary speed assessment system independent of said primary speed detector, said method including:

obtaining, using said secondary speed assessment system, first and second images of said vehicle, said second image being captured at a known time after said first image is captured;

selecting a reference point on said vehicle in said first image;

determining a location in said second image corresponding to an expected location of the selected reference point, based on the speed detected by the primary speed assessment system within a set percentage of the speed detected by the primary speed assessment system, in the time period between the capturing of said first and second images; and

comparing an actual location of said reference point in said second image with the expected location, such that if the actual location corresponds to the expected location, it may be concluded that the vehicle was travelling at the speed detected by the primary speed assessment system.

2. The method of claim 1, including displaying said first image to an operator, wherein said operator selects said reference point on said vehicle.

3. The method of claim 1, including displaying said second image to an operator, wherein said operator visually determines whether or not the expected location indicated on said second image matches the actual location of said reference point in said second image.

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

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

6. The method of claim 1, including the step of indicating a tolerance region in the second image around the expected location.

7. The method of claim 1, including the step of providing tolerance markers in the second image about the expected location.

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

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

10. 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 having known distance relationships in an imaged scene, and determining a perspective transform between real world locations of said calibration markers in said imaged scene and said pixel locations.

11. 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.

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

13. 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.

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

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

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

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

18. The method of claim 1, wherein a marker corresponding to the expected locations of said reference point is movable in said image.

22. A non-transitory computer readable medium containing software including a series of instructions executable by a processor to carry out a method according to claim 1.

19. A speed verification system for providing independent verification of speed detected by a primary speed assessment system, said primary speed assessment system using a primary speed detector to detect speed of a vehicle, said speed verification system using a secondary speed assessment system independent of said primary speed detector, said verification system including:

capturing means using said secondary speed assessment system for obtaining first and second images of said vehicle, said second image being captured a known time after said first image is captured;

selecting means for selecting a reference point on said vehicle in said first image;

determining means for determining a location in said second image corresponding to an expected location of the selected reference point, based on the speed detected by the primary speed assessment system within a set percentage of the speed detected by the primary speed assessment system, in the time period between the capturing of said first and second images, and

comparing means for comparing an actual location of said reference point in said second image with the expected location such that if the actual location corresponds to the expected location, it may be concluded that the vehicle was travelling at the speed detected by the primary speed assessment system.

20. The apparatus of claim 19, including display means for displaying said first image to an operator, and input means for allowing an operator to select said reference point.

21. The apparatus of claim 19, 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 reference point matches the expected location.