TELEVISION SURVEILLANCE SYSTEM

• US 3,590,151 A
• Filed: 11/30/1967
• Issued: 06/29/1971
• Est. Priority Date: 12/30/1966
• Status: Expired due to Term

• Current Assignee: Arlie L. Keith
• Original Assignee: Arlie L. Keith
• Inventors: Keith, Arlie L.
• Application Number:
  US04/687,029
• Time in Patent Office: 1,307 Days
• US Class Current: 348/155
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• 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: G07C 3/005 during manufacturing process
• CPC Class Codes: G07C 3/14 Quality control systems
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19613 Recognition of a predetermined image pattern or behaviour pattern indicating theft or intrusion
• CPC Class Codes: G08B 13/19634 Electrical details of the system, e.g. component blocks for carrying out specific functions
• CPC Class Codes: G08B 13/19691 Signalling events for better perception by user, e.g. indicating alarms by making display brighter, adding text, creating a sound
• CPC Class Codes: G08B 17/125 by using a video camera to detect fire or smoke

Abstract

A method and apparatus is disclosed by which surveillance may be maintained over a domain for detecting changes of interest in the domain and ignoring other changes. A parameter of the domain observed is scanned and sampled. The resulting sample data for individual sample points is digitized and used to update corresponding data averages over prior scans of the same sample points. Specified differences between the sample data and data average for a sample point result in modification of a suspicion value. Correlations in space and time of sample points having particular data changes further modifies the suspicion value. An output, such as an alarm, results from ultimate attainment of a predetermined suspicion value.

Claims

1. In a method for detecting a set quantity of change in a scene while ignoring lesser changes in said scene, the steps comprising;

scanning the scene in each of a plurality of separate time periods with a device responsive to radiation of wave energy, such as light, emanating from the scene for producing a scanning signal for each said timer period;

sampling said scanning signal to produce a plurality of sample signals representing the instantaneous level of wave energy emanating from a plurality of corresponding, preselected points in the scene during a given one of said time periods, said points being spaced remotely from each other along the line of scan, intervening points in the scene being ignored;

digitizing said sample siGnals to form digitized samples;

establishing digital comparison standards from prior digitized samples, each said comparison standard being representative of the condition of a respective one of said spaced points during at least one of said time periods;

comparing ones of said digitized samples produced during another time period with respective ones of said comparison standards and detecting nonzero differences therebetween;

comparing said difference with a reference and producing a suspicion signal comprising pulses in response to preselected nonzero discrepancies between said differences and said reference;

collecting said pulses; and

detecting collection of a preselected quantity of said pulses and producing an output in response to detection of said preselected quantity, said output indicating the occurrence of said set quantity of change in said scene.

2. The method of claim 1 wherein an initial pulse accumulation is established prior to said detection, said accumulation increases by reason of said collecting of pulses and the accumulation is periodically subjected to reduction by a predetermined amount to avoid production of an output in response to a long series of lesser changes in the scene.

3. In a device for selectively detecting a set quantity of change in a scene while ignoring lesser changes in said scene, the combination comprising:

means responsive to radiation of wave energy, such as light, emanating from the scene for scanning the scene in each of a sequence of time periods and for producing a plurality of sample signals during a given time period representative of the instantaneous level of wave energy emanating from a corresponding plurality of respective sample points in the scene, said sample points being spaced from each other along the line of scan across the scene, points in the scene other than said sample points being ignored;

a further plurality of sample signals being produced for each further scanning of said sample points in corresponding further ones of said time periods;

means for establishing comparison standards from prior sample signals, each said comparison standard being representative of the condition of a respective one of said spaced points during at least one of said time periods;

means for comparing ones of said sample signals produced during another of said time periods with respective ones of said comparison standards and detecting nonzero differences therebetween;

means for producing a suspicion signal comprising a pulse in response to a preselected nonzero discrepancy between one of said differences and a preselected reference;

means for collecting said pulses; and

means for detecting collection of a preselected number of said pulses and producing an output in response to detection of said preselected number, said output indicating the occurrence of said set quantity of change in said change in said scene.

4. The device of claim 3 wherein an accumulation of pulses is initially established and including means for changing the accumulated amount in one direction in response to said collecting of pulses and means for periodically changing accumulated amount in the opposite direction by a prescribed amount.

5. The device of claim 3 including means for digitizing said sample signals following production thereof and wherein said comparison standards, said reference signal and said suspicion signals are in digitized form.

6. The device of claim 3 wherein said means for scanning includes a plurality of units for effecting at least said scanning, each said unit being capable of scanning a separate scene, said units being arranged for time sharing at least said comparison standard establishing means, said comparing means, said suspicion signal producing means and said detecting means.

7. The device of claim 3 wherein said scene is an illuminated scene and said set quantity of change is a change in light level at at least one of said spaced points due to traversing tHereof by an intruder.

8. The device of claim 3 wherein said scene is an illuminated scene and said sample signals are representative of the illumination level at the points in the scene to which said sample signals correspond, and including means responsive to a plurality of said sample signals for detecting at least one of several abnormal conditions respecting the character of the illumination of the scene, said abnormal conditions including contrast outside a preselected range, excessive brightness in the scene and excessive dimness in the scene and means responsive to said detection of said abnormal condition for producing an output.

9. The device of claim 3 wherein said means for scanning and producing sample signals includes means for scanning said scene and producing an electrical scanning signal representative of the condition of the portion of the scene along the line of scan and means for sampling said electrical signal to periodically produce ones of said sample signals;

and including sample density selecting means adjustable for controlling the frequency of said sampling whereby to vary the spacing of points in the scene for which sample signals are produced.

10. The device of claim 3 wherein said means for scanning and producing sample signals includes means for scanning said scene and producing an electrical scanning signal representative of the condition of the portion of the scene along the line of scan and means for sampling said electrical signal to periodically produce ones of said sample signals;

and including sample programmer means adjustable for periodically preventing sampling so that no sample signals are produced for preselected ones of said spaced points in said scene, said sample programmer means including a switching network adjustable to constrain sampling to a group of points in a portion of the scene, said portion being smaller than the scannable scene, whereby detection of changes will be limited to said portion of said scene and changes in the condition of the remainder of the scene will be ignored.

11. The device of claim 3 wherein said wave energy is visible light.

12. The device of claim 3 wherein said wave energy is electromagnetic radiation outside the visible light range.

13. In a device for detecting a set quantity of change in a scene while ignoring lesser changes, the combination comprising:

means responsive to radiation of wave energy, such as light, emanating from the scene for scanning the scene in each of a sequence of time periods and for producing a plurality of sample signals during a given time period representative of the instantaneous level of wave energy emanating from a corresponding plurality of respective sample points in the scene, said sample points being spaced from each other along the line of scan across the scene, points in the scene other than said sample points being ignored;

a further plurality of sample signals being produced for each further scanning of said sample points in corresponding further ones of said time periods;

means for digitizing said sample signals to produce digitized samples;

means for establishing comparison standards from prior samples, each comparison standard being representative of the condition of a respective one of said spaced points during at least one of said time periods, wherein said means for establishing comparison standards includes memory means for storing a digital quantity substantially corresponding to the sum of prior digitized samples for the same point produced in a preselected number of prior time periods, the most significant bits of said digital amount substantially constituting an average of said prior digitized samples and constituting said comparison standard, and memory updating means for adding said difference to the least significant bits of said digital amount stored to update said digital amount to correspond to the value of the latest digitized sample, whereby a new comparison standard is produced and stored;

means for comparing ones of said digitized samples produced during another time period with respective ones of said comparison standards and detecting nonzero differences therebetween;

means for producing a suspicion signal comprising a pulse in response to a preselected nonzero discrepancy between one of said differences and a preselected reference;

means for collecting said pulses; and

means for detecting collection of a preselected quantity of said pulses and producing an output in response to detection of said preselected quantity, said output indicating the occurrence of said set quantity of change in said scene.

14. In a device for detecting a set quantity of change in a scene while ignoring lesser changes, the combination comprising:

means responsive to radiation of wave energy, such as light, emanating from the scene for scanning the scene in each of a sequence of time periods and for producing a plurality of sample signals during a given time period representative of the instantaneous level of wave energy emanating from a corresponding plurality of respective sample points in the scene, said sample points being spaced from each other along the line of scan across the scene, points in the scene other than said sample points being ignored;

a further plurality of sample signals being produced for each further scanning of said sample points in corresponding further ones of said time periods;

means for establishing comparison standards from prior sample signals, each said comparison standard being representative of the condition of a respective one of said spaced points during at least one of said time periods;

means for comparing ones of said sample signals produced during another time period with respective ones of said comparison standards and detecting nonzero differences therebetween;

means for producing a suspicion signal comprising a pulse in response to a preselected nonzero discrepancy between one of said differences and a reference;

means responsive to said comparing means for producing a further suspicion signal comprising a further pulse in response to a further preselected discrepancy between ones of said differences, said ones of said differences each corresponding to a different point in said scene, said different points being located near each other in said scene;

means for collecting said pulses; and

means for detecting collection of a preselected quantity of said pulses and producing an output in response to detection of said preselected quantity, said output indicating the occurrence of a set quantity of change in said scene.

15. Apparatus for maintaining observation of a zonal domain and responsive to a significant change in said domain, comprising in combination, means capable of successively scanning said zone for producing sample signals related to the light level at spaced segments on the path of scan, means for digitizing said sample signals, means for averaging over a plurality of scans the digitized signals for each of respective ones of said segments, means for comparing said digitized signals with the corresponding one of said averages, said comparing means being responsive to differences of preselected magnitude between corresponding ones of said digitized signals and averages for producing suspicion signals, and means responsive to a preselected quantity of suspicion signals for providing an output, whereby said apparatus provides an output in response to significant changes in light levels in said zone corresponding to a change in said domain.

16. The apparatus defined in claim 15 in which said scanning means includes at least one television camera for producing a video signal corresponding in amplitude to the light level in said zone along the path scanned and sampling means responsive to said video signal for producing spaced samples of said video signal, said samples comprising said sample signals.

17. The apparatus defined in claim 16 including a high frequency clock and a first counter having a serial input from said clock and a plurality of parallel outputs pulsed at descending fractions of the clock frequency, sweep generator means responsive to the output of said first counter for scanning the beam of said television camera through a preselected scanning pattern, a second counter having a serial input from one of the fractional outputs of said first counter and having parallel outputs pulsed at diminishing fractions of the frequency of the input thereto, a matching counter connected to the parallel outputs of said first and second counters and responsive to coincidence of such counter outputs for energizing said sampling means to cause same to sample said video signal when the electron beam of said television camera is aimed at a preselected point in said zone.

18. The apparatus defined in claim 17 in which said sweep generator means comprises a horizontal sweep generator and a vertical sweep generator for controlling the path of scan of said television camera and further including alternate field generator means for reversing said second counter each time the zone is scanned whereby to allow energization of said sampling means for different sets of points in alternate scans of said zone.

19. The apparatus defined in claim 17 in which said scanning pattern comprises a plurality of successive scan lines on which said segments are located, said segments defining and being evenly spaced along spaced loci angled with respect to said scan lines, whereby an intruder moving in said zone will pass through ones of said segments changing the light intensity of at least some thereof for energizing said output means.

20. The apparatus defined in claim 15 in which said averaging means includes memory means for storing an average signal Naver corresponding to previous scans of a segment, updating means connected in circuit with the input and output of said memory means and energizable from said digitizing means by a digitized signal Np for providing an updated value Naver for updating said memory for said segment in accordance with the relation wherein k is the number of scans over which N is averaged.

21. The apparatus defined in claim 15 in which said averaging means includes memory means for storing digitized average signals for ones of said segments scanned, said digitized average signals each comprising a most significant part and a least significant part, said most significant part at least approximating an average of digitized sample signals for a plurality of prior scans of the corresponding segment of said zone, said comparing means including means responsive to said most significant part and to a digitized sample signal for a current scan of said corresponding segment for determining the difference between said most significant part and said digitized sample signal and further including suspicion signal generating means responsive to a difference in excess of a limit for generating a suspicion signal, said averaging means further including means for adding said difference to said least significant part of said digitized average signal for producing a new digitized average signal, means for applying said new digitized average to said memory to replace said first-mentioned average signal.

22. The apparatus defined in claim 15 including register means for registering the suspicion signals for a scanned segment, counting means responsive to occurrence of a suspicion signal for a first scanned segment for providing outputs after counting preselected numbers of subsequently scanned segments, gate means responsive to said outputs from said counting means and to further suspicion signals for energizing said register means to register still further suspicion signals, said register means being arranged to weight said still further suspicion signals more heavily than said first-mentioned suspicion signal, said further suspicion signals corresponding to at Least one of segments near said first scanned segment in said zone taken in the same scan, segments near said first scanned segment in said zone taken in succeeding scans, and the same segment taken in succeeding scans.

23. The apparatus defined in claim 15 including a memory for storing said suspicion signals, means for adding suspicion signals from said comparing means to stored suspicion signals from said memory to provide a new suspicion signal and means for applying said new suspicion signal to said memory to replace said stored signals to increase the suspicion count stored in said memory in relation to changes in light level at segments of the zone scanned.

24. The apparatus defined in claim 23 including means for dispersing said suspicion signals at a predetermined rate.

25. The apparatus defined in claim 15 in which said output means includes a counter, means for resetting said counter at periodic intervals at least including a single scan of said zone, means for establishing reference levels, means responsive to suspicion signals exceeding said reference levels for actuating said counter, means for establishing a further reference level, a comparator responsive to a value in said counter exceeding said further reference for providing said output, said counter enabling said apparatus to rapidly detect changes in light intensity at numerous segments in a single scan and to quickly provide said output as a result thereof.

26. Apparatus for detecting changes in a view scene, comprising in combination, means for repetitively scanning the scene and for producing an electrical signal related in instantaneous amplitude to the intensity of radiation for the scanned portions in the scene, means for sampling said electrical signal, means for comparing a sample of said electrical signal with an average of corresponding samples for previous scans, means responsive to a deviation in excess of a predetermined value in a sample from said average for establishing a suspicion level signal, means responsive to further changes in excess of a predetermined value in further samples near said first-mentioned sample for adding to said suspicion level, comparison means responsive to a given suspicion level beyond a limit for providing an output.

27. A method of surveillance, comprising the steps, repetitively scanning a scene over which surveillance is to be maintained and producing an electrical signal related to the instantaneous light level in the portion of the scene being scanned, detecting a first set of points in the scene scanned for which the level of said electrical signals differ from the level of other such electrical signals produced in previous scans of points at least near the respective points of said first set of points, adding to a suspicion level as a function of the number of points in a second set of points, said second set comprising points of said first set at which said difference differs from preselected values, providing an output in response to a change of said suspicion level past a preset limit.

28. The apparatus defined in claim 15 including also means for producing a signal which is a function of the location of said changes spatially in said domain.

29. The apparatus defined in claim 15 including also means for producing a signal which is a function of the location of said changes spatially in said domain and for reacting to a time-spaced plurality of said signals for tracking said changes.

30. The apparatus defined in claim 15 including also means for producing a signal which is a function of the location of said changes spatially in said domain and for reacting to a consecutively appearing plurality of said signals for tracing said changes.

31. In apparatus for detecting a change in the condition of a domain, for use with means for scanning a parameter of said domain and producing a signal representative of the scanned parameters, the combination comprising:

means for sampling said signal to produce samples thereof;

means for averaging samples respectively related to selected portions of said domain to produce averages; and

interpreting means for interpreting said averages and samples and including suspicion count means responsive to the relative values of corresponding samples and averages for accumulating data indicative of selected changes of said parameter at ones of said portions and producing an output signal when and only when such accumulated data attains a predetermined value.

32. The device defined in claim 31 including digitizing means following said sampling means for digitizing said samples;

and in which said averaging means is interposed between said digitizing means and interpreting means for averaging, over a plurality of scans of said domain, the digitized samples for respective ones of said portions of said domain to produce said averages;

said interpreting means further includes comparison means for comparing said digitized samples with corresponding ones of said averages, said comparison means being responsive to deviations between said digitized samples and the corresponding averages; and

said suspicion count means includes means responsive to ones of said deviations in excess of a predetermined value for establishing suspicion level signals, means responsive to deviations in excess of a predetermined value in further samples near said first-mentioned sample in said domain for adding to said suspicion level signals and further comparison means responsive to a suspicion level exceeding a limit for providing an alarm.