Method and Apparatus for a Velocity Detection System Using Optical Growth Rate

• US 20060034489A1
• Filed: 07/21/2005
• Published: 02/16/2006
• Est. Priority Date: 07/21/2004
• Status: Active Grant

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: McClanahan, Stephen A.
• Granted Patent: US 7,333,634 B2
• Time in Patent Office: Days
• US Class Current: 382/107
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 19/52 Determining velocity
• 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 7/246 using feature-based methods, e.g. the tracking of corners or segments

Abstract

The present invention is a velocity detection system and method. In accordance with an embodiment of the invention, a series of still images of moving automobiles are taken at known intervals. An Image processor algorithm is used to determine local features of the moving automobile and in conjunction with known optical formulas, the velocity of the moving object can be determined. Once the velocity is determined, all of the moving automobiles are highlighted with their calculated velocity on a liquid crystal display screen. Images may be exported into flash memory for future reference.

Claims

1. A method for determining the velocity of a moving object, the method comprising the steps of:

locating an image capture plane;

capturing a first image at a first time interval from the image capture plane location, the first image comprising an image of at least one moving object;

capturing a second image at a second time interval from the image capture plane location, the second image comprising an image of at least one moving object and wherein the second time interval is greater than the first time interval;

determining the rate of growth of the image of the at least one moving object based on a dimensional comparison between the image of the at least one moving object from the first image and the image of the at least one moving object from the second image; and

calculating the velocity of the at least one moving object based on the rate of growth of the image of the moving object relative to the image capture plane.

2. The method of claim 1, wherein the image capture plane location is constant.

3. The method of claim 1, further comprising capturing a plurality of images of the at least one moving object at a plurality of successive time intervals from the image capture plane location.

4. The method of claim 1, further comprising storing the captured images on an electronic storage medium.

5. The method of claim 1, wherein the step of determining the rate of growth of the image of the at least one moving object based on a dimensional comparison between the first image and the second image, further comprises:

measuring an image dimension of the at least one moving object from either the first image or the second image;

estimating the actual dimension of the at least one moving object;

determining a threshold level based on the estimated actual dimension of the at least one moving object;

comparing the image dimension of the at least one moving object with the threshold level to determine the approximate distance of the at least one moving object from the image capture plane; and

determining the rate of growth of the image of the at least one moving object by comparing the image dimension of the at least one moving object of the first image with the image dimension of the at least one moving object of the second image and the approximate distance of the at least one moving object from the image capture plane.

6. The method of claim 5, wherein the step of estimating the actual dimension of the at least one moving object further comprises identifying a substantially constant dimension within the physical environment of the at least one moving object and comparing the dimension of the image of the at least one moving object to the identified substantially constant dimension.

7. The method of claim 6, wherein the at least one moving object is a moving vehicle, the dimension of the image of the at least one moving object is the width of the vehicle and the substantially constant dimension within the physical environment of the at least one moving object is the width of a roadway lane.

8. The method of claim 1, further comprising the step of verifying the calculated velocity of the at least one moving object by comparing subsequent calculated velocities of the at least one moving object based upon images captured at successive time intervals.

9. The method of claim 5, wherein the step of measuring an image dimension of the at least one moving object from either the first image or the second image further comprises employing a computer vision algorithm to measure an image dimension from said image.

10. The method of claim 1, wherein the image capture plane location is changing.

11. The method of claim 10, further comprising the steps of:

measuring the rate of change of the location of the image capture plane; and

calculating the velocity of the at least one moving object based on the rate of growth of the image of the at least one moving object relative to the rate of change of the location of the image capture plane.

12. The method of claim 1, wherein the at least one moving object further comprises a plurality of moving objects.

13. The method of claim 1, wherein the image capture plane location is changing and the at least one moving object further comprises a plurality of moving objects.

14. The method of claim 13, wherein the plurality of moving objects further comprises at least one stationary object having a rate of growth resulting from the change in location of the image capture plane.

15. The method of claim 14, further comprising the step of identifying the at least one stationary object from the plurality of moving objects.

16. The method of claim 15, further comprising the steps of:

determining a rate of change of the location of the image capture plane;

determining an expected growth rate for a stationary object based on the rate of change of the location of the image capture plane; and

comparing the expected growth rate for a stationary object to the rate of growth of the at least one stationary object to identify the at least one stationary object having a rate of growth substantially equal to the expected growth rate.

17. The method of claim 5, wherein the image dimension is selected from the group consisting of the height of the image, the width of the image and the area of the image.

18. The method of claim 1, further comprising the step of displaying the velocity of the at least one moving object to a user.

19. A method for determining the velocity of a moving vehicle, the method comprising the steps of:

locating an image capture plane;

capturing a first image of a moving vehicle at a first time interval from the image capture plane location;

capturing a second image of the moving vehicle at a second time interval from the image capture plane location, wherein the second time interval is greater than the first time interval;

measuring the width of the vehicle from the first captured image;

determining the approximate distance of the moving vehicle from the image capture plane location by comparing the width of the vehicle from the first captured image with the width of the roadway;

measuring the height of the vehicle from the first captured image;

measuring the height of the vehicle from the second captured image;

determining the change in height of the image of the moving vehicle based on a comparison between the height of the vehicle in the first image and the height of the vehicle in the second image; and

calculating the velocity of the moving vehicle based on the change in height of the image of the moving vehicle and the approximate distance of the moving vehicle from the image capture plane location.

20. A system for determining the velocity of a moving vehicle, the system comprising:

a machine vision camera to capture a plurality of images at a plurality of successive time intervals, the plurality of images further comprising an image of at least one moving object;

a machine vision processor to determine the rate of growth of the image of the at least one moving object based on a dimensional comparison between at least two of the plurality of images captured by the machine vision camera and to calculate the velocity of the at least one moving object based on the determined rate of growth of the image of the at least one moving object.

21. The system of claim 20, wherein the machine vision camera is a machine vision smart camera.

22. The system of claim 20, wherein the machine vision processor further comprises an algorithm to measure an image dimension of the at least one moving object from an image, estimate the actual dimension of the at least one moving object, determine a threshold level based on the estimated actual dimension of the at least one moving object, compare the image dimension of the at least one moving object with the threshold level to determine the approximate distance of the at least one moving object from the machine vision camera, and determine the rate of growth of the image of the at least one moving object by comparing the image dimension of the at least one moving object of the first image with the image dimension of the at least one moving object of the second image and the approximate distance of the at least one moving object from the machine vision camera.

23. The system of claim 20, further comprising a visual output to display the captured images and the results of the calculated velocity.

24. The system of claim 20, further comprising a user interface in circuit communication with the machine vision camera and the machine vision processor.

25. The system of claim 20, further comprising an image storage medium to store the plurality of captured images and the calculated velocities.

26. The system of claim 20, further comprising a global positioning system.