Periodic motion detection with applications to multi-grabbing

• US 20060262958A1
• Filed: 05/19/2005
• Published: 11/23/2006
• Est. Priority Date: 05/19/2005
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: ObjectVideo Incorporated (Alarm.com Holdings, Inc.)
• Inventors: Chosak, Andrew J., Myers, Gary W., Haering, Niels, Zhang, Zhong, Venetianer, Peter L., Lipton, Alan J., Yin, Weihong, Madden, Donald G., Clark, John Ian Wallace
• Granted Patent: US 7,613,322 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06T 2207/30241 Trajectory
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 20/52 Surveillance or monitoring of activities, e.g. for recognising suspicious objects recognising microscopic objects G06V20/69
• CPC Class Codes: G08B 13/19615 wherein said pattern is defined by the user

Abstract

A method of video surveillance may include performing on input video at least one of the operations selected from the group consisting of motion detection and change detection, recording a motion pattern based on a result of said at least one of the operations, and analyzing the motion pattern to detect periodic motion in the video. A video surveillance apparatus may include a change detector, a motion detector, and/or a combination motion/change detector, a pattern analyzer, and a periodic motion detector.

Claims

1. A method of video surveillance comprising:

performing on input video at least one of the operations selected from the group consisting of motion detection and change detection;

recording a motion pattern based on a result of said at least one of the operations; and

analyzing the motion pattern to detect periodic motion in the video.

2. The method according to claim 1, wherein said analyzing the motion pattern comprises:

defining one or more blocks of each frame of said video; and

detecting whether each said block is a motion block.

3. The method according to claim 2, wherein said detecting whether each said block is a motion block comprises:

applying a search window to the block;

determining a number of foreground pixels present in the block; and

comparing the number of foreground pixels present in the block with a threshold value.

4. The method according to claim 3, wherein said detecting whether each said block is a motion block further comprises:

determining a period of time for which each block has had its number of foreground pixels exceed said threshold; and

comparing said period of time with a time threshold to determine if said block should be stored and further analyzed.

5. The method according to claim 1, wherein said analyzing the motion pattern comprises:

obtaining an array of at least two sets of pixel coordinates corresponding to blocks defined on a video frame and defined as motion blocks and at least two corresponding time stamps; and

for each set of pixel coordinates and respective time stamp, comparing the time stamp to other time stamps of other sets of pixel coordinates in the array to determine if the differences between the time stamp and the other time stamps are within a difference threshold.

6. The method according to claim 5, wherein said analyzing the motion pattern further comprises:

defining a periodic motion counter for each set of pixel coordinates; and

incrementing the periodic motion counter for a particular set of pixel coordinates for each other set of pixel coordinates having a corresponding time stamp within said difference threshold of the time stamp corresponding to said particular set of coordinates.

7. The method according to claim 6, wherein said analyzing the motion pattern further comprises:

comparing each periodic motion counter with a motion counter threshold to determine if the periodic motion counter exceeds the motion counter threshold,

wherein periodic motion is detected if the periodic motion counter exceeds the motion counter threshold.

8. The method according to claim 1, further comprising:

generating at least one alert if periodic motion is detected.

9. A computer-readable medium containing instructions that, when executed on a computer system, cause the computer system to implement the method according to claim 1.

10. A video-based surveillance system comprising:

a computer system; and

the computer-readable medium according to claim 9, said computer-readable medium coupled to said computer system to enable said computer system to read and execute said instructions.

11. The video surveillance system according to claim 10, further comprising:

at least one video source coupled to said computer system to provide said video data.

12. Application-specific hardware designed to implement the method according to claim 1.

13. The application-specific hardware according to claim 12, wherein said application-specific hardware includes at least one component selected from the group consisting of:

an application-specific integrated circuit, a field-programmable gate array, and a special-purpose processor.

14. A method of multi-grabbing detection comprising the method of video surveillance according to claim 1, and further comprising:

detecting said periodic motion as multi-grabbing.

15. Video surveillance apparatus comprising:

a component selected from the group consisting of;

a change detector, a motion detector, and a combination motion/change detector;

wherein said component is to receive input video and to output motion data;

a motion pattern analyzer to receive said motion data and to output motion pattern data; and

a periodic motion detector to receive said motion pattern data.

16. The video surveillance apparatus according to claim 15, wherein said motion data comprises at least one foreground mask.

17. The video surveillance apparatus according to claim 15, wherein said motion pattern data comprises an array of pixel coordinates and corresponding time stamps.

18. The video surveillance apparatus according to claim 17, wherein said periodic motion detector is arranged to compare differences between pairs of said time stamps to a time threshold and to maintain and update a counter corresponding to each set of pixel coordinates based on said comparisons.

19. The video surveillance apparatus according to claim 15, wherein said motion pattern analyzer comprises:

a motion block detector to receive said motion data and to detect one or more motion blocks; and

a motion temporal change recorder to check the persistence of each motion block.

20. The video surveillance apparatus according to claim 19, wherein said motion temporal change detector compares a duration of time during which a given motion block has been considered to be a motion block with a time threshold to determine if the motion block has been sufficiently persistent.

21. A multi-grabbing detection apparatus comprising the video surveillance apparatus according to claim 15, wherein said periodic motion is detected as multi-grabbing.