Tracking apparatus

• US 5,557,543 A
• Filed: 04/15/1994
• Issued: 09/17/1996
• Est. Priority Date: 04/29/1993
• Status: Expired due to Term

• Current Assignee: MBDA UK Ltd. (MBDA SAS)
• Original Assignee: British Aerospace, Inc.
• Inventors: Parsons, Timothy J.
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US08/228,396
• Time in Patent Office: 886 Days
• Field of Search: 364/516, 235/411, 356/3, 342/55, 342/56, 342/58, 342/160
• US Class Current: 701/207
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30248 Vehicle exterior or interior
• CPC Class Codes: G06T 7/251 involving models
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components
• CPC Class Codes: G06V 2201/08 Detecting or categorising vehicles

Abstract

Apparatus suitable for tracking a road vehicle from an aerial platform uses a correlator (5) for processing data received from a thermal imager (1). The apparatus derives a binary template for use by the correlator (5), the template (13) being based on points of high curvature (12) in an object to be tracked. The invention shows a significant reduction in mistracking and drift compared with conventional correlation trackers under the conditions of high density of features similar in nature to the object of interest, such as typifies the imagery obtained from a ground-pointing camera mounted on an aerial platform.

Claims

1. Target tracking apparatus including:

input means, for receiving from an imager, a first set of data which comprises an image representing a viewed scene containing a target to be tracked, and for generating a second set of data which comprises a reference patch defining an area within said viewed scene containing the target;

template generating means for receiving said second set of data and for generating a third set of data which comprises a binary template representing the target;

and correlator means for receiving said first, second and third sets of data and for performing a multiplicative correlation process on said first, second and third sets of data and for generating a fix point representing the position of the target within said viewed scene.

2. Target tracking apparatus as claimed in claim 1 in which said template generating means includes:

edge detection means for producing edge maps of the target contained within the reference patch;

curvature generation means for identifying regions of high curvature in said edge maps and producing a curvature image of the target;

binarisation means for producing a binary image from said curvature image; and

dilation means for executing a morphological dilation around high curvature points in said binary image thereby generating a binary template.

3. Target tracking apparatus as claimed in claim 1 and further including an acquisition module for generating an initial reference patch.

4. Target tracking apparatus including:

input means, for receiving from an imager, a first set of data which comprises an image representing a viewed scene containing a target to be tracked, and for generating a second set of data which comprises a reference patch defining an area within said viewed scene containing the target;

template generating means for receiving said second set of data and for generating a third set of data which comprises a binary template representing the target;

and correlator means for receiving said second and third sets of data and for performing a subtractive correlation between said second and third sets of data and for generating a fix point representing the position of the target within said viewed scene.

5. Target tracking apparatus as claimed in claim 4 in which said correlator means includes:

a subdivision module for subdividing said binary template and said reference patch into respective sub-patches; and

feature-point matching means for determining a best match between respective sub-patches thereby to generate said fix-point.

6. Target tracking apparatus as claimed in claim 4 in which said template generating means includes:

edge detection means for producing edge maps of the target contained within the reference patch;

curvature generation means for identifying regions of high curvature in said edge maps and producing a curvature image of the target;

binarisation means for producing a binary image from said curvature image; and

dilation means for executing a morphological dilation around high curvature points in said binary image thereby generating a binary template.

7. Target tracking apparatus as claimed in claim 4 and further including an acquisition module for generating an initial reference patch.