Tracking objects with markers

• US 8,224,024 B2
• Filed: 10/04/2006
• Issued: 07/17/2012
• Est. Priority Date: 10/04/2005
• Status: Active Grant

• Current Assignee: Thales Visionix Incorporated (Thales SA)
• Original Assignee: Intersense Incorporated
• Inventors: Foxlin, Eric, Naimark, Leonid
• Primary Examiner(s): Le, Brian Q
• Assistant Examiner(s): BROOKS, JULIAN D
• Application Number:
  US11/543,008
• Publication Number:
  US 20070081695A1
• Time in Patent Office: 2,113 Days
• Field of Search: 382/103, 348/135, 348/137, 348/139, 348/142, 348/146, 348/169, 348/208.2
• US Class Current: 382/103
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

The spatial location and azimuth of an object are computed from the locations, in a single camera image, of exactly two points on the object and information about an orientation of the object.

One or more groups of four or more collinear markers are located in an image, and for each group, first and second outer markers are determined, the distances from each outer marker to the nearest marker in the same group are compared, and the outer marker with a closer nearest marker is identified as the first outer marker. Based on known distances between the outer markers and the marker nearest the first outer marker, an amount of perspective distortion of the group of markers in the image is estimated. Based on the perspective distortion, relative distances from each other point in the group to one of the outer markers are determined. Based on the relative distances, the group is identified.

Claims

1. A method comprising obtaining a camera image from a camera and processing said camera image in a data processor by computing the spatial location and azimuth of an object from the locations, in said camera image, of exactly two points on the object, and information about an orientation of the object, and generating one or more signals representative of the location and azimuth of the object, wherein computing the azimuth of the object comprises:

receiving coordinate information for images, on an imaging device of a camera, of two points on an object,

receiving pitch information from a sensor on the object,

using the coordinate information and the pitch information to obtain candidate values for the azimuth of the object,

selecting one azimuth value based on an evaluation of the candidate azimuth values in equations relating the coordinate information and pitch information to distances of the points from the camera.