Method and apparatus for covertly determining the rate of relative motion between two objects

• US 7,171,028 B2
• Filed: 11/22/2002
• Issued: 01/30/2007
• Est. Priority Date: 11/22/2002
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Roberts, Gregory A., von Thal, German
• Primary Examiner(s): Bali; Vikkram
• Assistant Examiner(s): Bhatnagar; Anand
• Application Number:
  US10/301,950
• Publication Number:
  US 20040101167A1
• Time in Patent Office: 1,530 Days
• Field of Search: 382/106, 382/107, 382/100, 382/103, 734/88, 356/27, 348/154
• US Class Current: 382/107
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves

Abstract

Apparatus and methods for covertly determining the rate of motion between a pixel-based imaging device and a target being viewed by the pixel-based imaging device. The method involves using the pixel-based imaging device to acquire a first and a second digital image of the target. The second digital image is acquired a time interval after the first digital image. The time interval and pixel counts for the pixel set within the first and the second digital image representing a particular portion of the target are then used to determine a rate of relative motion between the pixel-based imaging device and the target. Advantageously, the rate of relative motion is determined covertly such that the locations of the pixel-based imaging device and the target are not disclosed or broadcast to third parties.

Claims

1. A method for determining a rate of relative motion between a moving target and a pixel-based imaging device, the method comprising:

acquiring a first digital image of the moving target with the pixel-based imaging device;

selecting a first pixel set from the first digital image having at least one particular data value representing at least a portion of the moving target, and determining the pixel count of the first pixel set;

using the pixel count for the first pixel set to determine a first distance separating the pixel-based imaging device and the moving target when the first digital image was acquired;

acquiring a second digital image of the moving target with the pixel-based imaging device after expiration of a time interval;

selecting a second pixel set from the second digital image having at least one particular data value representing at least a portion of the moving target, and determining the pixel count of the second pixel set;

using the pixel count for the second pixel set to determine a second distance separating the pixel-based imaging device and the moving target when the second digital image was acquired;

using the difference between the first and second distances in the first and second digital images and the time interval to determine a rate of relative motion between the pixel-based imaging device and the moving target.

2. The method of claim 1, wherein determining a rate of relative motion between the pixel-based imaging device and the moving target by using the first and second distances and the time interval comprises subtracting the second distance from the first distance and then dividing by the time interval.

3. The method of claim 1, wherein:

using the pixel count for the first pixel set to determine a first distance separating the pixel-based imaging device and the moving target when the first digital image was acquired comprises accessing correlation data; and

using the pixel count for the second pixel set to determine a second distance separating the pixel-based imaging device and the moving target when the second digital image was acquired comprises accessing the correlation data.

4. The method of claim 1, wherein the rate of relative motion is a rate of closure between the pixel-based imaging device and the target.

5. The method of claim 1, wherein the rate of relative motion is a rate of separation of the pixel-based imaging device from the target.

6. The method of claim 1, further comprising displaying the rate of relative motion to a user.

7. The method of claim 1, further comprising providing a speed warning to a user when the rate of relative motion exceeds a threshold level.

8. The method of claim 1, wherein:

the target is disposed on a first platform; and

the pixel-based imaging device is disposed on a second platform.

9. The method of claim 1, wherein:

the target is disposed on an aircraft; and

the pixel-based imaging device is disposed on another aircraft.

10. The method of claim 1, wherein the selections of the first and second pixel sets are at least partially based on pixel information content.

11. The method of claim 10, wherein the pixel information content comprises image data.

12. A method for determining a rate of relative motion between a moving target and a pixel-based imaging device, the method comprising:

acquiring a first digital image of the target with the pixel-based imaging device;

selecting a first pixel set from the first digital image having data content representing at least a portion of the target, and determining the pixel count of the first pixel set;

acquiring a second digital image of the target with the pixel-based imaging device after expiration of a time interval;

selecting a second pixel set from the second digital image having data content representing at least a portion of the target, and determining the pixel count of the second pixel set;

determining a pixel count change for at least a portion of the target as represented in the first digital image and the second digital image; and

using the pixel count change and the time interval to derive the rate of relative motion.

13. The method of claim 12, wherein using the pixel count change and the time interval to derive the rate of relative motion comprises:

accessing correlation data to determine a differential distance associated with the pixel count change; and

dividing the differential distance by the time interval.

14. A system for determining a rate of relative motion between a moving target and an object, the system comprising:

a pixel-based imaging device disposed on the object, the pixel-based imaging device acquiring a first and a second digital image of the moving target, the second digital image being acquired after expiration of a time interval from when the first digital image was acquired; and

a computer executable module for using a number of pixels in a first pixel set and a second pixel set, selected from the first and second digital images, respectively, which pixel sets have data content representing at least a portion of the target in each of the first and second digital images, and the time interval, to determine a rate of relative motion between the pixel-based imaging device and the moving target.

15. The system of claim 14, further comprising at least one database including data correlating pixels counts with distances.

16. The system of claim 14, wherein the computer executable module comprises:

a computer executable sub-module for selecting a first pixel set from the first digital image, the first pixel set having a data content representing at least a portion of the moving target;

a computer executable sub-module for determining a pixel count for the first pixel set;

a computer executable sub-module for using the pixel count for the first pixel set to determine a first distance separating the pixel-based imaging device and the moving target when the first digital image was acquired;

a computer executable sub-module for selecting a second pixel set from the second digital image, the second pixel set having a data content representing the at least a portion of the moving target;

a computer executable sub-module for determining a pixel count for the second pixel set;

a computer executable sub-module for using the pixel count for the second pixel set to determine a second distance separating the pixel-based imaging device and the moving target when the second digital image was acquired; and

a computer executable sub-module for determining a rate of relative motion between the pixel-based imaging device and the moving target by subtracting the second distance from the first distance and then dividing by the time interval.

17. The system of claim 14, wherein the computer executable module comprises:

a computer executable sub-module for determining a pixel count change for at least a portion of the moving target as represented in the first digital image and the second digital image; and

a computer executable sub-module for using the pixel count change and the time interval to derive the rate of relative motion.

18. The system of claim 14, wherein the pixel-based imaging device comprises a digital camera.

19. Apparatus for determining a rate of relative motion between a pixel-based imaging device and a moving target, the apparatus comprising a computer executable module for using pixels in a plurality of pixel sets selected from a plurality of digital images that are made up from the pixel sets, one of the digital images being acquired in time before the other,

the pixel sets each having a data content representing at least a portion of the target in the plurality of digital images of the target produced by the pixel-based imaging device to determine, together with a time interval separating the acquisition of the plurality of digital images, a rate of relative motion between the pixel-based imaging device and the target.

20. An aircraft, comprising:

a pixel-based imaging device for acquiring a first digital image and a second digital image of at least portions of a moving mobile platform, the second digital image being acquired after expiration of a time interval from when said first digital image was acquired; and

a computer executable module for using a plurality of pixels in a first pixel set making up a portion of the first digital image, and a plurality of pixels in a second pixel set making up a portion of the second digital image, which pixel sets each represent at least a portion of the moving mobile platform in the first and second digital images, and the time interval, determine a rate of relative motion between the aircraft and the moving mobile platform.