Method and apparatus for establishing a north reference for inertial measurement units using scene correlation

Patent metadata

Field	Value
Publication number	US-9418430-B2
Application number	US-201414505979-A
Country	US
Kind code	B2
Filing date	Oct 3, 2014
Priority date	Oct 3, 2013
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A scene correlation-based target system and related methods are provided. A reference image depicts a remotely-positioned object having identifiable characteristics, wherein a reference directional vector is established relative to the reference image. A target image of a general vicinity of the remotely-positioned object has an unknown directional vector, the target image having at least a portion of the identifiable characteristics. An inertial measuring unit has a scene correlation system, wherein the scene correlation system matches the portion of the identifiable characteristics of the target image with the identifiable characteristics of the reference image, wherein a slew angle between the reference image and the target image is calculated. A target image directional vector is derived from the calculated slew angle and the reference directional vector.

First claim

The invention claimed is:

1. A scene correlation-based target system, comprising:
a first camera operable in a first electromagnetic spectrum and a second camera operable in a second electromagnetic spectrum different than the first electromagnetic spectrum, the first camera located at a first position and the second camera located a second position different than the first position, and wherein the first and second positions are adjacent combat theater;
a target remote from the first and second cameras positioned in an engagement area;
a reference image captured by the first camera in the first electromagnetic spectrum at the first position depicting a remotely-positioned reference scene including a contrast differential boundary line matching a profile of the remotely-positioned reference scene, wherein a known reference directional vector is established between the first camera and a remotely-positioned reference object in the reference scene;
a first range established from the first camera at the first position to the remotely-positioned reference object;
a second range established from the second camera at the second position to the target;
a target image captured by the second camera in the second electromagnetic spectrum at the second position and including the target located near a general vicinity of the remotely-positioned reference object having an unknown directional vector between the second camera and the target, the target image having at least a portion of the contrast differential boundary line matching the profile of the remotely-positioned reference scene;
an inertial measuring unit having a scene correlation system, wherein the scene correlation system matches the portion of the contrast differential boundary line matching the profile of the remotely-positioned reference scene of the target image with the contrast differential boundary line matching the profile of the remotely-positioned reference scene of the reference image, wherein an angle between the reference image and the target image is calculated;
a target image directional vector derived from the calculated angle, and the reference directional vector; and
a calculated target location in the engagement area derived from the target image directional vector and the second range.

2. The scene correlation-based target system of claim 1 , wherein the reference directional vector is a North vector.

3. The scene correlation-based target system of claim 1 , wherein both the target and the remotely-positioned reference object are positioned at least 2 kilometers (km) away from the first camera and the second camera to reduce parallax.

4. The scene correlation-based target system of claim 1 , wherein the scene correlation system matches the portion of the contrast differential boundary line matching the profile of the remotely-positioned reference scene of the target image with the contrast differential boundary line matching the profile of the remotely-positioned reference scene of the reference image by directly overlying the target image atop the reference image and calculating an offset error of the contrast differential boundary line matching the profile of the remotely-positioned reference scene in the target image with the contrast differential boundary line matching the profile of the remotely-positioned reference scene in the reference image.

5. The scene correlation-based target system of claim 4 , wherein the differences in contrast are determined by pixel correlation.

6. The scene correlation-based target system of claim 1 , wherein contrast differential boundary line matching the profile of the remotely-positioned reference object further comprises a line drawing defining a boundary between the remotely-positioned reference object and a background of each of the reference image and target image.

7. The scene correlation-based target system of claim 1 , wherein each of the reference image and the target image are stored in a system memory.

8. The scene correlation-based target system of claim 1 , wherein the target image directional vector is provided with an azimuth and an altitude.

9. The scene correlation-based target system of claim 1 , wherein for each of the reference image and target image, the contrast differential boundary line matches an entirety of a visible profile of the remotely-positioned reference scene, wherein the reference image is captured in a visible spectrum.

10. The scene correlation-based portable target system of claim 1 , wherein the second camera is incorporated into a pair of night vision goggles and the second electromagnetic spectrum is infrared.

11. The scene correlation-based portable target system of claim 1 , wherein the first electromagnetic spectrum is visible light and the second electromagnetic spectrum is infrared.

12. A panoramic scene correlation-based target system comprising:
a first camera operable in a first electromagnetic spectrum and a second camera operable in a second electromagnetic spectrum, the first camera positioned at a first position and the second camera positioned at a second position different than the first position while operated by an operator adjacent combat theater;
a target remote from the camera positioned in an engagement area;
a panoramic reference image captured by the first camera at the first position depicting a remotely-positioned reference scene having an identifiable profile outline, wherein a reference directional vector is established relative to an object in the panoramic reference image;
a plurality of target images captured by the second camera at the second position near a general vicinity of the remotely-positioned reference scene, each of the plurality of target images having an unknown directional vector, wherein at least one of the plurality of target images having at least a portion of the identifiable profile outline;
an inertial measuring unit having a scene correlation system, wherein the scene correlation system matches a line drawing corresponding to a contrast differential of the portion of the identifiable profile outline of the at least one of the plurality of target images with a line drawing corresponding to a contrast differential of the identifiable profile outline of the panoramic reference image; and
a target image directional vector derived from the matched line drawings corresponding to the contrast differentials of the identifiable profile outlines between the at least one of the plurality of target images and the panoramic reference image and a calculated target location in the engagement area derived from the target image directional vector and second camera at the second position.

13. The panoramic scene correlation-based target system of claim 12 , wherein the reference directional vector is a North vector.

14. The scene correlation-based target system of claim 12 , wherein, when the target image center is directly overlaid the reference image center, the scene correlation system matches the line drawings corresponding to the contrast differential of the identifiable profile outlines between the at least one of the plurality of target images and the panoramic reference directional vector by matching differences in contrast between the line drawing corresponding to the contrast differential of the identifiable profile outline within the panoramic reference image and a background of the panoramic reference image with differences in contrast between the portion of the line drawings corresponding to the contrast differential of the identifiable profile outline within the target image and a background of the target image.

15. A method

Assignees

• Bae Sys Inf & Elect Sys Integ

Inventors

• Choiniere Michael J
• Cirillo Brendan P
• Costantino Robert W
• Frey Robert D
• Hu Haijun
• O'Donnell Brian F
• Richards David A

Classifications

• G01C21/1656

  with passive imaging devices, e.g. cameras · CPC title

• G01C15/00

  Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00 · CPC title

• G06K9/00671

  Physics · mapped topic

• G06T2207/30244

  Camera pose · CPC title

• G06T7/0044 Primary

  Physics · mapped topic