Realtime object tracking system

• US 7,684,592 B2
• Filed: 01/14/2008
• Issued: 03/23/2010
• Est. Priority Date: 08/10/1998
• Status: Expired due to Term

• Current Assignee: Jolly Seven, Series 70 of Allied Security Trust I (Allied Security Trust)
• Original Assignee: Cybernet Systems Corporation
• Inventors: Paul, George V., Beach, Glenn J., Cohen, Charles J., Jacobus, Charles J.
• Primary Examiner(s): TUCKER, WESLEY J
• Application Number:
  US12/013,717
• Publication Number:
  US 20090116692A1
• Time in Patent Office: 799 Days
• Field of Search: 382/103, 382/107, 382/164, 382/165, 382/209
• US Class Current: 382/103
• CPC Class Codes: A63F 2300/1093 using visible light
• CPC Class Codes: A63F 2300/6045 for mapping control signals received from the input arrangement into game commands
• CPC Class Codes: A63F 2300/69 Involving elements of the real world in the game world, e.g. measurement in live races, real video
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• CPC Class Codes: G06V 40/20 Movements or behaviour, e.g. gesture recognition recognition of facial expressions G06V40/16
• CPC Class Codes: G06V 40/28 Recognition of hand or arm movements, e.g. recognition of deaf sign language static hand signs G06V40/113

Abstract

A real-time computer vision system tracks one or more objects moving in a scene using a target location technique which does not involve searching. The imaging hardware includes a color camera, frame grabber and processor. The software consists of the low-level image grabbing software and a tracking algorithm. The system tracks objects based on the color, motion and/or shape of the object in the image. A color matching function is used to compute three measures of the target'"'"'s probable location based on the target color, shape and motion. The method then computes the most probable location of the target using a weighting technique. Once the system is running, a graphical user interface displays the live image from the color camera on the computer screen. The operator can then use the mouse to select a target for tracking. The system will then keep track of the moving target in the scene in real-time.

Claims

1. A method of tracking a target, comprising the steps of:

inputting a sequence of images representative of a scene;

selecting a target in the scene;

computing with a processor the median color of a region around the selected target, and storing this as the color of the target;

computing a two-dimensional template of the target based upon the color of the target, and storing this template as the shape of the target;

computing the center of the target based upon its shape;

a) comparing the center of the target to the center of the target in the previous image of the sequence to determine the motion of the target, if any;

b) determining the probable new location of the target based upon the target color, shape and motion;

c) using a weighing technique to determine the most probable new location of the target; and

d) tracking the target by repeating steps a)-c) for each new image in the sequence of images.

2. The method of claim 1, wherein the step of selecting a target in the scene includes the step of user-selecting the target on a computer screen through a graphical user interface.

3. The method of claim 2, wherein the graphical user interface provides a bounding box surrounding the target superimposed on each image as it is displayed on the screen.

4. The method of claim 1, further including the step of enabling a match between the color of the target in the subsequent image to the color of the target in a previous image despite differences arising from target lighting and shadows.

5. The method of claim 1, further including the step of enabling a match between the color of the target in the subsequent image to the color of the target in a previous image within a threshold of hue.

6. The method of claim 1, wherein step of comparing the center of the target in the subsequent image to the center of the target in the initial image includes a comparison of pixels in an RGB format.

7. The method of claim 1, further including the step of determining if the target has moved outside of the scene.

8. The method of claim 1, further including the step of finding a weighted average of color to compute the center of the target based upon color alone.

9. The method of claim 1, wherein the step of computing a two-dimensional template of the target is done through segmenting a region defined by a predetermined closeness of color as an estimate of target shape.

10. The method of claim 1, further including the step of continuing to track the target when the target moves in front of or behind a similarly colored object in the scene.

11. The method of claim 1, further including the step of continuing to track the target when the target and input image move in relation to one another.