Method and apparatus for imaging a target using cloud obscuration prediction and detection

• US 7,414,706 B2
• Filed: 12/22/2004
• Issued: 08/19/2008
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Nichols, William Mark, LaColla, Gerard Michael, Farmer, Randolph Gregory
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US11/021,450
• Publication Number:
  US 20060132753A1
• Time in Patent Office: 1,336 Days
• Field of Search: 356/4.01, 356/5.07, 356/28, 382/103, 382/107
• US Class Current: 356/5.07
• CPC Class Codes: G01S 13/865 Combination of radar systems with lidar systems
• CPC Class Codes: G01S 13/867 Combination of radar systems with cameras
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/95 for meteorological use
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A method is provided for imaging targets using an unmanned air vehicle. The method comprises the steps of making a determination of cloud obscuration of a target, selecting an imaging sensor based on the cloud obscuration determination, and using the selected imaging sensor to produce an image of the target. An apparatus that performs the method is also provided.

Claims

1. A method of imaging targets using an unmanned air vehicle, the method comprising the steps of:

making a determination of cloud obscuration of a target;

selecting an imaging sensor based on the cloud obscuration determination; and

using the selected imaging sensor to produce an image of the target;

wherein the step of making a determination of cloud obscuration of a target comprises the steps of;

firing a laser beam toward an area of interest;

measuring a time for a reflected beam to return to a sensor; and

comparing the measured time to an expected time.

2. The method of claim 1, wherein the step of making a determination of cloud obscuration of a target further comprises the step of:

detecting clouds based on image content.

3. The method of claim 1, wherein the step of making a determination of cloud obscuration of a target further comprises the steps of:

taking an image of the target in the area of interest; and

determining an offset between the laser beam and the target in the image.

4. A method of imaging targets using an unmanned air vehicle, the method comprising the steps of:

making a determination of cloud obscuration of a target;

selecting an imaging sensor based on the cloud obscuration determination; and

using the selected imaging sensor to produce an image of the target;

the step of detecting clouds based on image content comprises the steps of;

taking an image of an area of interest;

identifying cloud edges in the image of the area of interest;

summing the number of cloud edges; and

comparing the total number of cloud edges to a predetermined number.

5. The method of claim 4, wherein the step of identifying cloud edges comprises the step of:

comparing relative velocities of at least two of the edges.

6. The method of claim 4, wherein the step of making a determination of cloud obscuration of a target further comprises the step of:

detecting clouds based on the relative movement of the clouds.

7. An apparatus for imaging targets from an air vehicle, the apparatus comprising:

a sensing system for determining cloud obscuration of a target;

a processor for using forecasts of precipitation in an area of interest to determine a probability of cloud obscuration along a line of sight between the air vehicle position and a target;

at least two different imaging sensors; and

a controller for selecting one of the target sensors for imaging the target, based on the determined cloud obscuration;

wherein the sensing system comprises;

a laser for producing a beam of light capable of being reflected by clouds; and

a processor for measuring a time for a reflected beam to return to a sensor and for comparing the measured time to an expected time.

8. An apparatus for imaging targets from an air vehicle, the apparatus comprising:

a sensing system for determining cloud obscuration of a target;

a processor for using forecasts of precipitation in an area of interest to determine a probability of cloud obscuration along a line of sight between the air vehicle position and a target;

at least two different imaging sensors; and

a controller for selecting one of the target sensors for imaging the target, based on the determined cloud obscuration;

wherein the sensing system comprises;

a camera for producing images of an area of interest; and

a processor for identifying cloud edges in the images, for summing the cloud edges, and for comparing the total number of cloud edges to a predetermined number.

9. The apparatus of claim 8, wherein the processor identifies cloud edges by comparing relative velocities of at least two of the edges in different image frames.

10. The apparatus of claim 8, wherein the sensing system detects clouds based on the relative movement of the clouds.

11. The apparatus of claim 8, wherein the sensing system further comprises:

a laser for shining a laser beam toward the area of interest; and

the processor measures an offset between the laser beam and the target, and compares the measured offset to a predetermined offset.