Target direction determination method and system

• US 9,897,445 B2
• Filed: 09/14/2014
• Issued: 02/20/2018
• Est. Priority Date: 10/06/2013
• Status: Active Grant

• Current Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Original Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Inventors: Bar Hillel, Gil, Zalmanson, Garry Haim
• Primary Examiner(s): Shibru, Helen
• Application Number:
  US15/021,055
• Publication Number:
  US 20160223326A1
• Time in Patent Office: 1,255 Days
• Field of Search: 348 36, 348143
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01C 1/04 combined with cameras
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: G01C 5/00 Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels G01C3/20, G01C3/30 take precedence
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: H04N 23/69 Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture

Abstract

A method of determining a direction of a target in a ground referential, the method including: acquiring an image of a scene including the target and a control object using a camera; obtaining position data of the camera and control object using a geo-spatial positioning system; determining a control direction from the camera to the control object in the ground referential using the position data; estimating a camera attitude in the ground referential using the control direction; determining the target direction from the camera to the target using the estimated camera attitude and a pixel position of the target in the image.

Claims

1. A method of determining a direction of a target in a ground referential, the method comprising:

acquiring an image of a scene including the target and a control object using a camera;

obtaining position data of the camera and control object using a geo-spatial positioning system;

determining a control direction from the camera to the control object in the ground referential using said position data;

estimating a camera attitude in the ground referential using the control direction;

determining the target direction from the camera to the target using the estimated camera attitude and a pixel position of the target in the image.

2. The method according to claim 1, further comprising leveling of the camera using a level instrument and wherein estimating the camera attitude is performed using the leveling of the camera.

3. The method according to claim 1, wherein the image further includes at least one additional control object, the method further comprises:

obtaining additional position data regarding the at least one additional control object using the geo-spatial positioning system;

determining at least one additional control direction from the camera to the at least one additional control object in the ground referential using said additional position data;

and wherein estimating the camera attitude is performed using the at least one additional control direction.

4. The method according to claim 3, wherein estimating the camera attitude using the at least one additional control direction comprises refining the estimated camera attitude using the at least one additional control direction by:

estimating the at least one additional control direction based on the estimated camera attitude and on a pixel position of the additional control object on the image;

comparing the at least one estimated additional control direction to the at least one additional control direction determined based on the additional position data to obtain a direction disagreement vector;

computing a correction rotation matrix to minimize the direction disagreement vector.

5. The method according to claim 3, wherein estimating the camera attitude using the at least one additional control direction comprises solving the equations provided by the camera model applied at the two control objects.

6. The method according to claim 1, wherein acquiring the image comprises:

capturing a plurality of overlapping elementary images by modifying an orientation of the camera so as to scan a predetermined area of the scene, and

forming a panoramic image by mosaicing of the elementary images.

7. The method according to claim 6, wherein the control object and the target belong to different elementary images.

8. The method according to claim 6, wherein the image further includes at least one additional control object and the method further comprises:

obtaining additional position data regarding the at least one additional control object using the geo-spatial positioning system;

determining at least one additional control direction from the camera to the at least one additional control object in the ground referential using said additional position data;

and wherein;

estimating the camera attitude is performed using the at least one additional control direction, and

the at least one additional control object and the control object belong to different elementary images.

9. The method according to claim 1, wherein the ground referential is a East, North, Up referential centered on the camera position.

10. The method according claim 1, wherein the geo-spatial positioning system is a Global Navigation Satellite System (GNSS).

11. The method according to claim 10, wherein the position data are provided without using differential correction and/or without using real time kinematic procedures.

12. A surveying module for determining a direction of a target in a ground referential, the surveying module comprising:

an image input unit configured for receiving an image of a scene including the target and a control object, the image being acquired using a camera;

a position data input unit configured for receiving position data of the camera and of the control object from a geo-spatial positioning system; and

a target direction processing unit configured for;

determining a control direction from the camera to the control object in the ground referential using said position data;

estimating a camera attitude in the ground referential using the control direction; and

determining the target direction from the camera to the target using the estimated camera attitude and a pixel position of the target in the image.

13. The surveying module according to claim 12, wherein the target direction processing unit is further configured for, when the image received by the image input unit further includes at least one additional control object and the position data received by the position data input unit further includes additional position data of the at least one additional control object:

determining at least one additional control direction from the camera to the at least one additional control object in the ground referential using said additional position data;

and wherein estimating the camera attitude is performed using the at least one additional control direction.

14. A surveying system comprising:

a camera including a geo-spatial position receiver configured for receiving position signals from a geo-spatial positioning system and a geo-spatial position processor for determining camera position data from said position signals; and

a surveying module according to claim 12.

15. The surveying system of claim 14, further comprising a control object including a geo-spatial position receiver configured for receiving position signals of the control object from the geo-spatial positioning system and a communication unit configured for transferring said position signals to the geo-spatial position processor, the geo-spatial position processor being further configured for determining position data of the control object from said control object position signals.