Video movement detector

• US 4,458,266 A
• Filed: 06/11/1982
• Issued: 07/03/1984
• Est. Priority Date: 10/22/1980
• Status: Expired due to Fees

• Current Assignee: Commonwealth of Australia
• Original Assignee: Commonwealth of Australia
• Inventors: Mahoney, Trevor W.
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US06/395,076
• Time in Patent Office: 753 Days
• Field of Search: 358/105, 358/108, 340/541
• US Class Current: 348/155
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19606 Discriminating between target movement or movement in an area of interest and other non-signicative movements, e.g. target movements induced by camera shake or movements of pets, falling leaves, rotating fan

Abstract

The system of detecting motion by means of a video detector which consists in directing at least one television camera (20) into the surveillance area, and reproducing the image from the said camera on a television (25) screen, characterized in that the television screen display is divided into a matrix of elemental detection zones (15) positioned in a selected number of columnms (1 to 14) with each detection zone being a selected number of scan lines (0-8) high, processing the elemental detection zones in each column in a sequential manner by integrating (28) a first detection zone in the column and at the last scan line converting to digital format in an analogue-to-digital converter (29) and placing in a memory (49) and resetting the integrator to process the next elemental detection zone and so on and subsequently comparing scans with earlier corresponding scans to detect errors representing movement, further characterized by programmable window means generated by a rectangular window generator (51) to elect which error signals are to actuate a display or alarm (47).

Claims

1. The method of detecting motion by means of a video detector which consists in:

(a) directing at least one television camera (20) into the surveillance area,

(b) reproducing the image from the said camera on a TV screen (25),

(c) dividing the TV screen display into a matrix of elemental detection zones (15) positioned in a selected number of columns with each detection zone (15) being a selected number of scan lines high,

(d) processing the elemental detection zones (15) in each column in a sequential manner with at least one selected column processed in each TV frame by submitting a first detection zone (15) in the said column to an integrator (28) and continuing integration of the signal in the said column until, at the end of a selected gate pulse (75), a start conversion pulse is applied to an analogue-to-digital converter (29) to issue a "busy" signal and holding the "busy" condition while conversion to a digital format is in progress, whereby at the last scan line conversion to digital format in the analogue-to-digital converter (29) occurs,

(e) placing the digital format into a memory (49),

(f) resetting the integrator (28) to process the next elemental detection zone (15) of the said column until the zones (15) in the said column are completed and then sequentially similarly submitting all remaining columns to the said integrator (28) one for each succeeding frame,

(g) comparing subsequently produced scans with earlier corresponding scans to detect errors (62) representing movement, and

(h) defining by means of at least a window (16) of selectable dimensions those errors (62) to be directed to the alarm circuitry (47).

2. The method of claim 1 wherein a strobe signal (62) is added to any elemental detection zone (15) in the window (16) where a difference occurs between the earlier stored value and a subsequent value and initiating an alarm signal where such error (62) occurs in the said window (16).

3. The method of claim 1 or 2 wherein the said window (16) is programmable to have areas within the said window (16) deleted or areas outside of the said window (16) added to process only those elemental detection zones (15) selected for surveillance said programming being effected by a rectangle generator (51) whose height, width and position is adjustable and which is arranged after selection of a rectangle (63) to hold or delete the defined space to build a window (16) including only selected elemental detection zones (15).

4. The method of claim 1 or 2 wherein the lens aperture of the said video camera (20) is controlled by gating the video signal by the detection window (16) only and feeding the signal to a peak detector (66), and chopping (67) the signal by the line synchronisation pulses to provide a video signal to the lens whereby to control the said aperture independently of light values outside of the said window (16).

5. The method of claim 1 or 2 wherein the lines are interlaced, the processing of even scan lines in each elemental detection zone (15) in alternate columns, and processing of odd scan lines in each elemental detection zone (15) in the columns intermediate thereto.

6. The method of claim 1 or 2 wherein a plurality of TV cameras (73) are used, not exceeding the number of scan lines which define the height of each elemental detection zone (15), and the video signal from each TV camera (73) is coupled to its associated integrator (74) which is actuated to feed its output through a multiplexer (76) to the said analogue-to-digital converter (77) during the idle time between the start signal and the last line scan of a preceding integration of an elemental detection zone (15) and multiplexing (76) the signals from the multiple camera array (73) for memory storage (85) and subsequent processing for error detection.

7. The method of claim 1 or 2 wherein the said window (16) is programmable to have areas within the said window (16) deleted or areas outside of a said window (16) added to process only those elemental detection zones (15) selected for surveillance said programming being effected by a rectangle generator (51) whose height, width and position is adjustable and which is arranged after selection of a rectangle (63) to hold or delete the defined space to build a window (16) including only selected elemental detection zones (15), and wherein a strobe signal (62) is added to any elemental detection zone (15) in the window (16) where a predetermined difference occurs between the earlier stored value and a subsequent value and initiating an alarm signal where such error occurs in the said window (16), and wherein the lens aperture is controlled by the illumination existing only in the said window (16).

8. A video movement detector wherein at least one TV camera (20) is directed into the surveillance area to reproduce the image from the said camera (20) on a TV screen (25) characterized by means to divide the TV screen display into a matrix of elemental detection zones (15) positioned in a selected number of columns with each detection zone (15) being a selected number of scan lines high, an integrator (28) to process the elemental detection zones (15) in each column in a sequential manner within at least one selected column in each TV frame, an analogue-to-digital converter (29) to receive the integrated video signal at the last scan line of each elemental detection zone (15), a gate (27) to transfer the video signal from the said surveillance camera (20) to the said integrator (28) arranged to continue integration of the signal in the said column until, at the end of every selected gate pulse (75), a start conversion pulse is applied to the said analogue-to-digital converter (29) to issue a "busy" signal, means to hold the "busy" condition while conversion to the digital format is in progress, a memory (49) to receive and store the said data, means to reset the integrator (28) to process the next elemental detection zone (15) of the said column, gate means to sequentially similarly submit all remaining columns to the said integrator (28) at least one for each succeeding frame, and a comparator (48) for comparing subsequently produced scans with earlier corresponding scans to detect errors (62) representing movement, and means to define at least one window (16) of selectable dimensions on said TV screen display (25), and means to direct error signal (62) generated in said window (16) to indicator means (62, 47).

9. The video movement detector of claim 8 characterized by a strobe signal generator connected to add a strobe signal (62) to any elemental detection zone (15) in the window (16) where a predetermined difference occurs between the earlier stored value and a subsequent value and optionally an alarm signal generator (47) actuated where such error (62) occurs in the said window (16).

10. The video movement detector of claim 8 or 9 characterized by means to program the said window (16), and means to delete or add areas within the said window (16) or areas outside of a said window (16) to process only those elemental detection zones (15) selected for surveillance, said programming being effected by a rectangle generator (51) by adjusting height, width and position of a rectangle (63), and means to hold or delete the defined rectangular space to build a window (16) including only selected elemental detection zones (15).

11. The video movement detector of claim 8 or 9 characterized by means to control the lens aperture (26) of the said video camera (20) by gating the signal from the detection window (16) only, means to feed the signal to a peak detector (66), and means to chop (67) the signal by the line synchronisation pulses to provide a video signal to the lens and means to actuate the diaphragm of the said lens from the said video signal to control the said aperture independently of light values outside of the said window (16).

12. The video movement detector of claim 8 or 9 wherein the scan lines are interlaced, characterized by means to process even scan lines in each elemental detection zone (15) in alternate columns, and processing of odd scan lines in each elemental detection zone (15) in the columns intermediate thereto.

13. The video movement detector of claim 8 or 9 wherein a plurality of TV cameras (73) is used, not exceeding the number of scan lines which define the height of each elemental detection zone (15), characterized by means associated with each camera to feed its signal through a multiplexer (76) to the said analogue-to-digital converter (77) during the idle time between the start signal and the last line scan of a preceding integration of an elemental detection zone (15), and a multiplexer (78) to sequentially direct the signals from the said analogue-to-digital converter (77) to a memory storage (85) and subsequent processing for error detection.

14. The video movement detector of claim 8 or 9 characterized by means to program the said window (16), and means to delete or add areas within the said window (16) or areas outside of a said window (16) to process only those elemental detection zones (15) selected for surveillance, said programming being effected by a rectangle generator (51) by adjusting height, width and position of a rectangle (63), and means to hold or delete the defined rectangular space to build a window (16) including only selected elemental detection zones (15), and further characterized in that the lens aperture of the said video camera is variable and by gate means taking the signal from the detection window (16) only to avoid problem areas, means being provided to feed the signal to a peak detector (66) to provide a video signal to the lens coupling means being positioned to actuate the diaphragm of the said lens from the said video signal to control the said aperture independently of light values outside of the said window (16).

15. A video movement detector wherein a plurality of TV cameras (73) for each detection zone are directed into surveillance areas to reproduce the image from the said cameras (73) on a TV screen (92), characterized by means to divide the TV screen display into a matrix of elemental detection zones (15) positioned in a selected number of columns with each detection zone (15) being a selected number of scan lines high, means to define at least one window (16) of selectable dimension to select the elemental detection zones (15) to be processed, an integrator for each TV camera (73) to process the elemental detection zones (15) within each column in a sequential manner with at least one selected column processed in each TV frame, a multiplexer (76) receiving the signal from each integrator and sequentially feeding the signal to an analogue-to-digital converter (77) connected to the said multiplexer (76) to process the data at the last scan line of each elemental detection zone (15), means to apply to the analogue-to-digital converter a start conversion pulse at the end of every selected gate pulse to issue a "busy" signal, means to hold the "busy" condition while conversion to the digital format is in progress, a multiplexer (78) to direct the processed data to a memory (85) to store the said data, means to reset the integrator to process the next elemental detection zone (15) of the said column, gate means to sequentially similarly submit all remaining columns to the said integrators one for each succeeding frame, and a comparator (86) for comparing subsequently produced scans with earlier corresponding scans to detect errors representing movement, and means to indicate when and where such errors occur.