Method of boresight correlation of imager video to reference video

• US 7,912,247 B2
• Filed: 10/27/2008
• Issued: 03/22/2011
• Est. Priority Date: 09/15/2004
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Williams, Darin S., Kitchen, Edward N.
• Primary Examiner(s): Bhatnagar; Anand
• Application Number:
  US12/259,052
• Publication Number:
  US 20090046902A1
• Time in Patent Office: 876 Days
• Field of Search: 382/100, 382/103, 382/106, 382/107, 382/181, 382/190, 382/195, 382/199, 382/201, 382/203, 342/52, 342/53, 342/141, 250/316.1, 250/330, 250/336.1, 250/338.1, 250/341.8, 250/342, 250/495.1, 702/127, 702/135, 702/134, 348/169
• US Class Current: 382/103
• CPC Class Codes: F41G 7/007 Preparatory measures taken before the launching of the guided missiles
• CPC Class Codes: F41G 7/2226 comparing the observed data with stored target data, e.g. target configuration data
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/7803 Means for monitoring or calibrating
• CPC Class Codes: H04N 25/674 based on the scene itself, e.g. defocusing
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

The present invention provides for simple and streamlined boresight correlation of FLIR-to-missile video. Boresight correlation is performed with un-NUCed missile video, which allows boresight correlation and NUC to be performed simultaneously thereby reducing the time required to acquire a target and fire the missile. The current approach uses the motion of the missile seeker for NUCing to produce spatial gradient filtering in the missile image by differencing images as the seeker moves. This compensates DC non-uniformities in the image. A FLIR image is processed with a matching displace and subtract spatial filter constructed based on the tracked scene motion. The FLIR image is resampled to match the missile image resolution, and the two images are preprocessed and correlated using conventional methods. Improved NUC is provided by cross-referencing multiple measurements of each area of the scene as viewed by different pixels in the imager. This approach is based on the simple yet novel premise that every pixel in the array that looks at the same thing should see the same thing. As a result, the NUC terms adapt to non-uniformities in the imager and not the scene.

Claims

1. A method of correlating video from an imager to reference video, comprising:

using the temporal motion of the imager over a plurality of frames of video to form a first edge map;

measuring scene motion of the video;

spatially processing images in the reference video in accordance with the scene motion to locate at least some of the same edges to form a second edge map; and

correlating the first and second edge maps to provide registration.

2. The method of claim 1, wherein the first edge map is formed by differencing images in the video.

3. The method of claim 2, wherein a first frame of the video is subtracted from a second frame to form the first difference image.

4. The method of claim 1, further comprising resampling the second edge map to match the resolution of the first edge map.

5. The method of claim 1, wherein said imager captures IR video.

6. The method of claim 1, wherein the scene motion of the video is measured from inertial rate sensors or autocorrelation of the video.

7. A method of correlating video from an imager to reference video, comprising:

using the temporal motion of the imager over a plurality of frames of video to form a first edge map;

measuring scene motion of the video;

spatially processing images in the reference video with a displace and subtract filter in accordance with the measured scene motion to locate at least some of the same edges to form a second edge map; and

correlating the first and second edge maps to provide registration.

8. A method of correlating video from an imager to reference video, comprising:

using the temporal motion of the imager over a plurality of frames of video to form a first edge map, where the first edge map is formed by differencing images in the video, wherein a first frame of the video is subtracted from a second frame to form the first difference image, wherein subtracting images in the video compensates DC non-uniformities in the frames of video;

measuring scene motion of the video;

spatially processing images in the reference video in accordance with the scene motion to locate at least some of the same edges to form a second edge map; and

correlating the first and second edge maps to provide registration.

9. A method of correlating video from an imager to reference video, wherein said imager captures low-resolution IR video and a reference imager captures high-resolution IR reference video, comprising:

using the temporal motion of the imager over a plurality of frames of low-resolution IR video to form a first edge map;

measuring scene motion of the low-resolution IR video;

spatially processing images in the high-resolution IR reference video in accordance with the scene motion to locate at least some of the same edges to form a second edge map;

resampling the second edge map to match the resolution of the first edge map; and

correlating the first and second edge maps to provide registration.

10. A method of correlating low-resolution video from an imager to high-resolution reference video, comprising:

using the temporal motion of the imager over a plurality of frames of low-resolution video to delay and subtract successive frames to compensate the effects of DC non-uniformities in the frames and form a first edge map;

estimating scene motion of the video;

constructing a displace and subtract spatial filter based on the scene motion estimate;

processing images in the high-resolution reference video with the displace and subtract filter to locate at least some of the same edges to form a second edge map;

resampling the second edge map to match the resolution of the first edge map;

correlating the first and second edge maps; and

extracting registration information from the correlated first and second edge maps.

11. The method of claim 10, wherein said imager captures IR video.

12. The method of claim 10, wherein the scene motion of the video is estimated from inertial rate sensors or autocorrelation of the video.

13. A method of correlating video, comprising:

capturing low-resolution video with an imager;

capturing high-resolution reference video with a reference imager;

using the temporal motion of the imager over a plurality of frames of low-resolution video to form a first edge map;

measuring scene motion of the low-resolution video;

spatially processing images in the reference video in accordance with the scene motion to locate at least some of the same edges to form a second edge map;

resampling the second edge map to match the resolution of the first edge map; and

correlating the first and second edge maps to provide registration.

14. The method of claim 13, wherein the reference video is spatially processed with a displace and subtract filter in accordance with the measured scene motion.

15. The method of claim 13, wherein use of the temporal motion to form the first edge map compensates DC non-uniformities in the frames of video.