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

• US 20040101167A1
• Filed: 11/22/2002
• Published: 05/27/2004
• Est. Priority Date: 11/22/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Thal, German von, Roberts, Gregory A.
• Granted Patent: US 7,171,028 B2
• Time in Patent Office: Days
• 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 target and a pixel-based imaging device, the method comprising:

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

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

using at least portions 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 target.

2. The method of claim 1, wherein using at least portions 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 target comprises:

selecting a first pixel set from the first digital image, the first pixel set representing at least a portion of the target;

determining a pixel count for 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 target when the first digital image was acquired;

selecting a second pixel set from the second digital image, the second pixel set representing the at least a portion of the target;

determining a pixel count for 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 target when the second digital image was acquired; and

determining a rate of relative motion between the pixel-based imaging device and the target by using the first and second distances and the time interval.

3. The method of claim 2, wherein determining a rate of relative motion between the pixel-based imaging device and the 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.

4. The method of claim 2, wherein:

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

5. The method of claim 1, wherein using at least portions 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 target comprises:

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.

6. The method of claim 5, 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.

7. 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.

8. 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.

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

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

11. 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.

12. The method of claim 1, wherein:

the target is disposed on an aircraft; and

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

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

14. The method of claim 13, wherein the pixel information content comprises image data.

15. A system for determining a rate of relative motion between a first and second object, the system comprising:

a target disposed on the first object;

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

a computer executable module for using at least portions 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 target.

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

17. The system of claim 15, 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 representing at least a portion of the 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 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 representing the at least a portion of the 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 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 target by subtracting the second distance from the first distance and then dividing by the time interval.

18. The system of claim 15, wherein the computer executable module comprises:

a computer executable sub-module for 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

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

19. The system of claim 15, wherein the pixel-based imaging device comprises a digital camera.

20. Apparatus for determining a rate of relative motion between a pixel-based imaging device and a target, the apparatus comprising a computer executable module for using at least portions of a plurality of digital images of the target produced by the pixel-based imaging device to determine a rate of relative motion between the pixel-based imaging device and the target.

21. An aircraft, comprising:

a pixel-based imaging device for acquiring a first and a second digital image of at least a portion of another aircraft, the second digital image being acquired after expiration of a time interval; and

a computer executable module for, using at least portions of the first and second digital images and the time interval to determine a rate of relative motion between the aircraft and the another aircraft.