TV AREA CORRELATION TRACKER

• US 3,828,122 A
• Filed: 09/11/1972
• Issued: 08/06/1974
• Est. Priority Date: 09/29/1970
• Status: Expired due to Term

• Current Assignee: Richard D. Sondergard, Walter J. Mcphee
• Original Assignee: Richard D. Sondergard, Walter J. Mcphee
• Inventors: McPhee, Walter J., Sondergard, Richard D.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US05/287,940
• Time in Patent Office: 694 Days
• Field of Search: 178/DIG.21,6.8 250/23CT
• US Class Current: 348/170
• CPC Class Codes: G01S 3/7865 using correlation of the live video image with a stored image

Abstract

A means for tracking a target using a television monitoring system. A joy stick type control is used to position a rectangle of sampled video on a television monitor over a desired target. After pushing a target acquisition switch, the target is maintained within the rectangle by comparing a digital representation of the video signal for the rectangle with a smaller reference rectangle of the initially sampled video. The part of the larger rectangle that has the highest correlation with the reference rectangle is assumed to be the location of the target. Therefore, a feedback loop is used to reposition the larger rectangle until the point of maximum correlation is located at the center thereof. This comparison is made for each frame of video information of the television system. Simultaneously with the repositioning of the larger rectangle to centrally enclose the desired target, a camera of the television system is tending to reposition itself to locate the rectangle of sampled video within the center of the field of view. The physical repositioning of the camera is much slower than the electronic repositioning of the larger rectangle over the reference rectangle. The control loop that is used to maintain the target within the center of the field of view may be used to direct a missile or other conventional weapon toward the target.

Claims

1. A tracking system comprising:

a television system for monitoring a variable area, said television system including a camera and monitor means;

control means for selecting a first area containing a specific part of said variable area;

means for repositioning said camera so that said first area and specific part are centrally located on said monitor;

means for converting a video signal from said first area into a digital representation for each segment of said video signal;

gate controller for selecting a second area surrounded by said first area, said specific part being further centrally located within said second area;

clock means for sequentially shifting the transfer of selective processed digital representations of the video signal of the first area along the converting means to the gate controller;

initial memory for retaining the first said digital representation for said second area when said control means has selected said specific part;

current memory for retaining said digital representation until the next digital representation from another frame of said television system has been received;

means for correlating said initial memory against said current memory to obtain the location of maximum correlation between said digital representation of said initial and current memories;

correlation counter means for determining the number of bits of said digital representation of said second area that correspond with each location within said first area;

correlation memory means for retaining the maximum number of bits that correspond;

location means for noting the location where said maximum number was obtained; and

feedback means for altering said control means to maintain said second area which contains said specific part within the same center location of said first area, said repositioning means subsequently following said altered control means.

2. A tracking system comprising:

scanning means for monitoring a variable area, said scanning means including a camera and monitor means;

control means for selecting a first area containing a specific part of said variable area;

means for repositioning said camera so that said first area and specific part are centrally located on said monitor;

means for converting a video signal from said first area into a digital representation for each segment of said video signal;

gate controller for selecting a second area surrounded by said first area, said specific part being further centrally located within said second area;

clock means for sequentially shifting the transfer of selective processed digital representations of the video signal of the first area along the converting means to the gate controller;

initial memory for retaining the first said digital representation for said second area when said control means has selected said specific part;

current memory for retaining said digital representation until the next digital representation from another frame of said television system has been received;

means for correlating said initial memory against said current memory to obtain the location of maximum correlation between said digital representation of said initial and current memories;

correlation counter means for determining the number of bits of said digital representation of said second area that correspond with each location within said first area;

correlation memory means for retaining the maximum number of bits that correspond;

location means for noting the location where said maximum number was obtained; and

feedback means for altering said control means to maintain said second area which contains said specific part within the same center location of said first area, said repositioning means subsequently following said altered control means.