Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
  • G01V8/00—Prospecting or detecting by optical means
  • G01V8/10—Detecting, e.g. by using light barriers
  • G01V8/12—Detecting, e.g. by using light barriers using one transmitter and one receiver
  • G01V8/14—Detecting, e.g. by using light barriers using one transmitter and one receiver using reflectors
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B13/00—Burglar, theft or intruder alarms
  • G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
  • G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
  • G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
  • G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
  • G08B13/19602—Image analysis to detect motion of the intruder, e.g. by frame subtraction
  • G08B13/1961—Movement detection not involving frame subtraction, e.g. motion detection on the basis of luminance changes in the image
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B13/00—Burglar, theft or intruder alarms
  • G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
  • G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
  • G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
  • G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
  • G08B13/19639—Details of the system layout
  • G08B13/19641—Multiple cameras having overlapping views on a single scene
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/70—Circuitry for compensating brightness variation in the scene
  • H04N23/71—Circuitry for evaluating the brightness variation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/70—Circuitry for compensating brightness variation in the scene
  • H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
  • H04N7/188—Capturing isolated or intermittent images triggered by the occurrence of a predetermined event, e.g. an object reaching a predetermined position

Definitions

• the present invention relates to a perimeter security system by actively analyzing images reflected by a set of mirrors on a video camera.
• BACKGROUND TECHNOLOGY The most common perimeter security systems are based on detecting the crossing of a sensitive area by means of a cut-off device of one or more infrared beams. They generally consist of couple (s) of transmitter (s) and receiver (s) operating through a coding and / or synchronization of infrared beams pulsed between the transmitter or receivers. According to a first embodiment of said systems, the transmitter and the receiver are placed opposite each other on the sensitive area to be monitored, which is crossed by the infrared beam or beams.
• the total occultation by an object of the trajectory of a beam which corresponds to that of the lens located in front of the receiver, triggers an alarm if the cutoff of the beam, and therefore of the infrared signal, is greater than a generally configurable duration.
• the cutoff information is therefore of the binary type with or without receiving the infrared radiation emitted by the emitter.
• the number of beams, and therefore of cutoff information is limited as much as possible to the combination of one or more transmitters and receivers located on either side of the sensitive detection zone.
• this type of device requires wiring on both sides of the sensitive area and provides only a very partial protection of the space between the transmitting and receiving surfaces, ie limited to the surface of the lenses.
• receivers According to a second embodiment of said systems, the transmitter and the receiver are placed on the same side and are therefore associated with a reflector which sends back to the receiver the radiation emitted by the transmitter. They are generally of very short range and only allow operation when the area of reflection and therefore of detection is of a small and unique surface. Indeed, since the receiver consists of a single sensitive zone, the use of a large reflective surface only generates attenuation of the reflection if the object that crosses it is smaller and obscures than a single part of the surface of the reflector.
• the Image sensor consists of hundreds of thousands of sensitive elements which allows to have a high accuracy of analysis.
• the problems posed by this kind of device are numerous, however, the first being that the system in question is passive and that if an obstacle was introduced into the scene while the system is stopped, a crossing of the sensitive area behind the obstacle to the camera becomes undetectable by the system.
• variations in light and shadows make the equipment very sensitive to climatic conditions, the variations of the video signal is not the only fact of the passage of an object in the sensitive area.
• a fourth embodiment of said systems several cameras are used which offer the possibility of knowing very precisely by triangulation, the height of the object and the location of the crossing in the sensitive area between the cameras and the reflector or reflectors.
• Such an embodiment requires several cameras and a sophisticated image processing system because the received signals must be synchronous to detect and simultaneously measure a rapid variation in the field of these cameras.
• Patents EP1927957 and US2007 / 145272 are the documents of the closest state of the art. They describe a system that basically includes:
• a unit for analyzing and processing images and for controlling the camera adapted to define one or more frames for analyzing the image part or parts containing the aforementioned illuminating means and for analyzing this part of the image for the purpose of detecting any rapid variation of the video signal in the image area of the illuminating means corresponding to the passage of an object or a person between the assembly consisting of the camera and said means, the size of the image area occulted varying according to the crossing distance and the height of the object or the person carrying out the crossing in the zone masking said means.
• the problem that the present invention proposes to solve is to replace a set of cameras, whose signals must be synchronous to detect and simultaneously measure a rapid variation in the field of these cameras, by a set of mirrors with a price of is less expensive and requires a much less sophisticated image processing system because unique.
• the image parts are synchronous because they come from the same sensor, the same lens and a set of reflecting mirrors.
• the illuminating means having a very elongated vertical shape makes it possible to optimize the filling of the standard scene seen by a 4/3 format camera in a multitude of X / 3 synchronous image formats where X is equal to the number of mirrors.
• the mirrors are partially inserted into the field of view of the camera, each mirror having the same vertical orientation but of a different horizontal orientation so that the portion of the image seen by the camera on each of the mirrors always represents the scene compared in illuminating means.
• the means illuminating the scene seen by the camera and returning the light rays thereto:
• - is a reflector, reflector type, illuminated by at least one projector, capable of generating the image portion having the largest amplitude of video signal;
• - is a projector, consisting of a plurality of juxtaposed microprojectors, LED type, uniformly distributed over the entire height of said projector, emitting in the direction of said camera, capable of generating the image portion having the largest signal amplitude video.
• the system controls the forward and backward path of a controlled radiation because it generates an almost saturated signal on a known, illuminated and controlled part of the scene, namely the part of the scene reflected by the reflector whose direction of reflection of the light is known and controlled.
• the device can behave as a conventional video detection and visualization system to follow the evolution of the crossing in the field of view of the camera.
• the unit for analyzing and processing images and controlling the camera is adapted:
• the surface of the reflector or reflectors may not be uniformly reflecting so that the reflected light and therefore the signal value is not uniform over the entire height of the reflector, but variable slightly depending on the relevant part of it, so that it is not possible to simulate a non-occultation of the reflector by inserting by a reflective object of the same nature: the variable attenuation of reflection on the reflector of the system can be made by a light frosting on the reflector or by any other means having the same effect;
• each camera or reflector, or both can be equipped with a band pass filter whose transmittance wavelength is centered on the wavelength of the corresponding projector so that each camera mainly receives light rays from the corresponding projector and perceives little or no other radiation having another wavelength, this in order to reduce the influence of solar lighting or any other lighting device that is not part of the device: this selective filtering on the wavelength of the radiation makes it possible to increase the contrast between the image zone of the reflector and the rest of the image.
• FIG. 1 is a schematic profile of the system comprising a camera, two mirrors, two projectors and a reflex reflecting means;
• FIG. 2 is a schematic front view of the system according to Figure 1, highlighting the position of the mirrors;
• FIG 3 a video image seen by the camera on each of the mirrors;
• FIG. 4 is a schematic profile view of the system comprising a camera, two mirrors and an illuminating means consisting of the juxtaposition of microprojectors;
• FIG. 5 is a video image seen by the camera when the shutter settles on 100% of the maximum video signal in the area of the reflector;
• FIG. 6 is a video image seen by the camera when the shutter is locked on
• the system shown is of the type comprising:
• - means (3,7) adapted to emit or re-emit, in the visible but also in the visible near, a radiation illuminating the scene seen by the camera (1);
• a unit (4) for analyzing and processing images and for controlling the camera (1) adapted to define one or more frames for analyzing the image part or parts containing the illuminating means (3,7); ) and to analyze this part of the image for the purpose of detecting any rapid variation of the video signal, in the image area of said illuminating means, corresponding to the passage of an object or a person between the set consisting of the camera (1) and said means (3,7), the size of the hidden image zone varying according to the crossing distance and the height of the object or the person crossing in the zone hiding the illuminating medium ( 3.7).
• each mirror has the same vertical orientation but of a different horizontal orientation so that the image portion seen by The camera on each of the mirrors always represents the same scene in relation to the illuminating medium (3,7).
• the means able to illuminate the scene seen by the camera (1) and to return the light rays thereto, is a reflector (3), catadioptre type, illuminated by at least one projector (2), able to generate the image portion having the largest video signal amplitude;
• the means capable of illuminating the scene seen by the camera (1) and sending the light rays thereto is a projector (7), consisting of a plurality of juxtaposed microprojectors, of LED type, uniformly distributed over all the height of said projector, capable of generating the image portion having the largest video signal amplitude.
• the unit (4) for analyzing and processing images and for controlling the camera (1) is adapted: to control the electronic shutter thereof so as to vary the exposure time of the sensor , therefore the value of the signal supplied by said camera;
• the electronic shutter so that the shutter speed is not calculated to obtain a signal close to 100% on the image zone of the reflector but is calculated to obtain a value average of 50% of the maximum signal on the image parts complementary to that containing the means (3,7).
• the surface of the means (3,7) is not uniformly emitting or reflecting so that the transmitted light, therefore the value of the signal, is not uniform over the entire height of the latter, but varies slightly depending on the part concerned.
• the camera (1), or the means (3,7) is equipped with a bandpass filter whose transmittance wavelength is centered on the wavelength emitted or re-transmitted by the means (3,7) so that said camera mainly perceives light rays coming from said means (3,7) and perceives little or no other radiation having another wavelength.
• the system may comprise an additional processing and control unit which is adapted to receive the signal from the camera (1), to interact with the image analysis and processing unit (4) and to control switching on and off the projector (2,7) synchronously to the video signal, the duty cycle switching on / off of each said means, corresponding to the sensitization time of the associated sensor, so that the lighting power is higher during sensitization of the sensor and zero the rest of the time.
• an additional processing and control unit which is adapted to receive the signal from the camera (1), to interact with the image analysis and processing unit (4) and to control switching on and off the projector (2,7) synchronously to the video signal, the duty cycle switching on / off of each said means, corresponding to the sensitization time of the associated sensor, so that the lighting power is higher during sensitization of the sensor and zero the rest of the time.
• Said additional unit for processing and controlling the periodic ignition and extinguishing of the projector (2.7), is adapted to generate a lighting and extinction cycle which makes it possible to take a plurality of alternating images with and without lighting, in order to know by differential measurement between the two images, the proportion of the lighting of said projector (2.7) and to control the external lighting system such as solar lighting or as artificial lighting that would illuminate the area of detection.
• the unit (4) for analyzing and processing images and for controlling the camera (1) is adapted to analyze the variation of the portion of the image containing the illuminating means (3,7) as a function of the luminance of the video signal, hue and color saturation when the system is operating in the visible light spectrum range, in order to take into account the variation in hue or color saturation that may result from the object occultation of all or part of the reflector.
• the system comprises, arranged opposite, on each side of the zone to be monitored, at least two cameras (1), at least two illuminating means (3,7) and at least two sets of at least two mirrors (6,61), in order to have a system whose weak coverage area near each camera is compensated by the opposite camera and whose cross-checking of the fields of view makes it possible to obtain, by triangulation, the crossing distance by comparing the highest obscuration point on each of the image portions containing said illuminating means (3,7).

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geophysics (AREA)
• Image Analysis (AREA)
• Studio Devices (AREA)
• Length Measuring Devices By Optical Means (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2008
  • 2008-12-17 FR FR0807084A patent/FR2940000A1/fr active Pending
• 2009
  • 2009-04-07 FR FR0901688A patent/FR2939942B1/fr not_active Expired - Fee Related
  • 2009-12-04 US US13/140,568 patent/US20110249121A1/en not_active Abandoned
  • 2009-12-04 EP EP09797067A patent/EP2382783A1/de not_active Withdrawn
  • 2009-12-04 WO PCT/FR2009/001388 patent/WO2010076407A1/fr active Application Filing

Non-Patent Citations (2)

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