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EP0448803B1 - Video control system - Google Patents

Video control system Download PDF

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Publication number
EP0448803B1
EP0448803B1 EP90124078A EP90124078A EP0448803B1 EP 0448803 B1 EP0448803 B1 EP 0448803B1 EP 90124078 A EP90124078 A EP 90124078A EP 90124078 A EP90124078 A EP 90124078A EP 0448803 B1 EP0448803 B1 EP 0448803B1
Authority
EP
European Patent Office
Prior art keywords
flash
area
frame
monitoring device
video monitoring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90124078A
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German (de)
French (fr)
Other versions
EP0448803A2 (en
EP0448803A3 (en
Inventor
Rainer Grundig E.M.V. Max Grundig Rumland
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
Original Assignee
Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
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Priority to AT90124078T priority Critical patent/ATE102726T1/en
Publication of EP0448803A2 publication Critical patent/EP0448803A2/en
Publication of EP0448803A3 publication Critical patent/EP0448803A3/en
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Publication of EP0448803B1 publication Critical patent/EP0448803B1/en
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Classifications

    • 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
    • G08B13/19652—Systems using zones in a single scene defined for different treatment, e.g. outer zone gives pre-alarm, inner zone gives alarm
    • 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
    • G08B13/19634—Electrical details of the system, e.g. component blocks for carrying out specific functions

Definitions

  • the invention relates to a video control device for the detection of stationary and moving objects in a delimited, preferably flat area with the aid of a surveillance camera.
  • Light barriers are often used to detect such objects. Although this type of monitoring is not very complex, it has the disadvantage that only objects that interrupt a light beam are recognized, so that the network of light beams must be very narrow. In order to recognize lying people or flat obstacles, the light barriers must be installed very low, which, however, can easily lead to errors in the evaluation, e.g. if There is snow. Additional video surveillance is necessary so that the surveillance area can be checked for the cause of the alarm in the event of an alarm by the surveillance personnel, so that the train is not stopped in the event of a false alarm.
  • a more advantageous method is monitoring with television cameras and automatic evaluation with a video controller.
  • movements are detected here, so that a pedestrian or a car in the surveillance area triggers the alarm. Since in this type of monitoring two images in succession are checked for changes, the detection of an object depends on its movement. Objects at rest are not recognized.
  • a source of error arises from changes in the image caused by the moving shadow of passing clouds or trees moving in the wind. In the dark there are problems with the light cones of car headlights.
  • the object of the invention is therefore to provide a monitoring device that is both stationary and also reliably detects moving objects in the surveillance area and at the same time reduces the probability of false alarms.
  • This object is achieved by taking two images for evaluation and storing them in an image memory, one of the images being taken without artificial lighting, while the second image with a flash which is arranged opposite the camera, the axis of the radiation cone of the Flash forms an angle with the axis of the camera, which is less than 180 °, is recorded.
  • a difference image is now created from the two images stored in the image memory, which only contains portions which have arisen from the lighting by the flash, while portions which have arisen due to the normal light are extinguished. If there is an object in the monitored area, the difference image results in a signal in the shadow areas that arise behind an object on the side facing away from the flash. The extent of these signals is evaluated. An alarm is triggered when a shadow is detected.
  • the monitoring device With the monitoring device according to the invention, three-dimensional objects can be recognized, it being irrelevant whether these are moving or at rest. By hiding the part of the image that is created by normal lighting, changes in the image that are caused by shadows as a result of normal lighting and the like and that lead to interference in known image processing systems are suppressed.
  • the area to be monitored can be limited by a mask if the detection area of the camera is larger than the area to be monitored.
  • the mask is electronically determined so that the excluded areas are not taken into account in the evaluation.
  • a second flash device which is arranged at a short distance next to the first, so that, for example, ruts in the snow in the direction of the plane in which the axis of the camera optics and the flash radiation cone lying, do not cause shadows. It is advantageous if the axis of the second flash has a slightly changed angle to the camera axis.
  • Limiting the spectral range of the flash and advantageously also of the camera also contributes to increasing the reliability of the evaluation, since the interference is reduced by this exclusion.
  • the TV cameras with semiconductor sensors CCD cameras
  • CCD cameras can still process a range from dark red to infrared, the blue, green and yellow areas are suppressed and an appropriate optical filter makes the scene still appear natural.
  • the image signals triggered by a limited spectral range can be fed to a central monitoring station for evaluation.
  • the light loss caused by the filter is compensated for by opening the diaphragm by 2 to 3 steps.
  • FIG. 1 shows a block diagram of an arrangement according to the invention
  • FIG. 2 shows the arrangement of flash unit (hereinafter referred to as flash) and camera using the example of a level crossing
  • FIG. 3 shows the image section with a restricted area and a three-dimensional object.
  • the camera 1 is connected to the masking device 2. Cables lead from this masking device 2 to the synch separator 3, to the image processing unit 12 and to the switch S1, which optionally connects the signal at the output of the masking device 2 to the image memory 6 or to the image memory 7.
  • the switch S1 is controlled by the switch control 5.
  • the synch separator 3 is still connected to the field recognition 4. This in turn has a connection to the switch control 5 and to the flash control 8, which is connected to the switch S2 and to the flash 9.
  • the image memories 6 and 7 are also connected to the differential circuit 11, to which the image processing unit 12 connects.
  • a connection leads from the image processing unit 12 to the alarm transmitter 13, which is connected to an alarm output unit 14.
  • the camera 1 and the flash 9 are arranged elevated on opposite sides of the surveillance area.
  • a possible arrangement is shown in FIG. 2a using the example of a level crossing.
  • the arrangement can consist of the camera K and the flash B or of the camera K and the flashes B1 and B2. Furthermore, an arrangement with more than two flashes is also possible if the area to be monitored has other conditions that require this.
  • a side view of the arrangement is shown in Fig. 2b. 2c shows a view from above.
  • the switch S2 is coupled to the barrier at a level crossing so that it activates the monitoring device when the barrier is closed.
  • the camera When the monitoring device is activated, the camera first records a first field and then a second field with flash lighting. These video signals pass through the masking device 2, in which everything that does not belong to the area to be monitored is hidden.
  • the masking device 2 In Figure 3a, the parts that are masked out by the masking device are shown hatched, so that only the area between the barriers remains. In the masking device 2 However, ascertained bumps or the rails, which can also interfere with the evaluation, can be hidden.
  • the manipulated in the masking device 2 image signal is firstly applied to the synch separator 3, in which the synchronization signals are separated, which are then processed in the field recognition 4.
  • the image portions hidden by the mask are fed to the image processing unit, so that these image portions are not taken into account in the image evaluation.
  • the manipulated image signal is optionally sent to the image memory 6 or the image memory 7 via the switch S1.
  • the switch S1 is brought into the respectively required position by the switch control 5, a switching signal being given by the field recognition 4 to the switch control 5.
  • the control takes place in such a way that a first field is stored in the image memory 6. This first field is under normal conditions, i.e. taken by the camera without flash.
  • the field detection 4 again sends a switching signal to the switch control 5 and the flash control 8 and the flash image now generated is stored in the image memory 7.
  • the field detection can output a switching signal after each field or every frame, which is evaluated in the switch control 5 or in the flash control 8.
  • the evaluation can advantageously take place in such a way that after the first Field in the image memory 6, one field is not evaluated and the next field is then written into the image memory 7, the flash 9 being triggered by the flash controller 8 when this field was recorded.
  • This field now contains image information that was obtained due to the normal lighting and additionally the image information that was caused by the flash.
  • the two fields are located in the image memories 6 and 7 and are subsequently manipulated in the differential circuit 11 by forming the difference from the corresponding image points of the image memory 6 and the image memory 7 pixel by pixel.
  • the resulting image which is evaluated in the image processing unit 12, only contains image information that was caused by the light of the flash. When displaying this image on the monitor, everything would be largely shown and visible, just like a normal picture. However, the disturbing external light sources, such as car headlights and their light cones, and their effects, such as the shadows caused by these light sources, are missing. Shadows are also invisible, which are caused by passing clouds or trees swaying in the wind and which can only be eliminated with great effort or not at all in the image evaluation using known image recording methods.
  • the image information that only results from the light of the flash creates a shadow on the side of the object facing away from the flash, as shown in FIG. 3 is represented by the area S, which indicates the presence of a three-dimensional object O in the surveillance area.
  • the unlit side of the object also remains black and is also referred to as shadow in the following.
  • the simplest way to evaluate the image is to use a shadow, i.e. recognize an area whose image values have black levels. If such an area is recognized, the alarm device 13 can emit an alarm, which is indicated acoustically or optically by the alarm output unit 14.
  • the image evaluation in the image processing unit 12 can be expanded as far as is necessary for meaningful monitoring. For example, the extent and shape of the area can be evaluated with a black level. In this way, an alarm can be suppressed, for example by a cigarette packet. Thanks to a more complex image processing system, brightening of the shadows created by scattered light can also be taken into account.
  • the size of the shadow depends on the position to the flash. An object that is close to the flash creates a smaller shadow than an object of the same size that is further away because the angle of incidence is flatter here.
  • Three-dimensional objects which, as already mentioned, are constantly in the same area in the area to be monitored, can be masked out by the masking device 2 or they can be excluded from the evaluation in the image processing unit 12.
  • An adaptation to different places of use is easily possible here, in that when the monitoring system is set up, the monitoring area is recorded in the manner described above and the shadows that are created are taught in and are not taken into account in the evaluation in the monitoring area.
  • the surveillance camera of the surveillance system is also used for surveillance by surveillance personnel, i.e. for displaying an image on a monitor, the field that was additionally exposed by flash can be replaced by the previous field stored in the other image memory.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Closed-Circuit Television Systems (AREA)
  • Image Processing (AREA)
  • Selective Calling Equipment (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Infrared light barriers or video control systems are used, as is known, in monitoring bounded, plane areas, for example a level crossing. However, both solutions have the disadvantage that they are unreliable or are of a very complicated design. The invention provides a video control system which permits reliable evaluation using simple means. For this purpose, a camera is used to take and store two fields in each case, one being taken without flash, and the other with. A differential image, now containing only signal components caused by the light of the flash is obtained from the two fields. Given the presence of a three-dimensional object in the monitored area, there is produced on the side of the object averted from the flash a shadow signal which is evaluated and, if necessary, fed to the alarm-triggering device. <IMAGE>

Description

Die Erfindung betrifft eine Videokontroll-Einrichtung zur zur Detektion von ruhenden und bewegten Objekten auf einem abgegrenzten, vorzugsweise ebenen Gebiet mit Hilfe einer Überwachungskamera.The invention relates to a video control device for the detection of stationary and moving objects in a delimited, preferably flat area with the aid of a surveillance camera.

Bei derartigen zu überwachenden Gebieten, wie z.B. einem beschrankten Bahnübergang, ist es wichtig, daß Objekte, die sich im Überwachungsbereich befinden, mit Sicherheit erkannt werden, auch wenn die äußeren Umstände ungünstig sind. Bei einem beschrankten Bahnübergang müssen Hindernisse, Personen oder Fahrzeuge erkannt werden.With such areas to be monitored, such as a restricted level crossing, it is important that objects located in the monitoring area are detected with certainty, even if the external circumstances are unfavorable. Obstacles, people or vehicles must be recognized when the level crossing is restricted.

Zum Erkennen von derartigen Objekten werden häufig Lichtschranken eingesetzt. Diese Art der Überwachung ist zwar nicht sehr aufwendig, hat aber den Nachteil, daß nur Objekte erkannt werden, die einen Lichtstrahl unterbrechen, so daß das Netz von Lichtstrahlen sehr eng sein muß. Um auch liegende Personen oder flache Hindernisse zu erkennen, müssen die Lichtschranken sehr tief angebracht werden, wodurch jedoch leicht Fehler bei der Auswertung entstehen, wenn z.B. Schnee liegt. So ist eine zusätzliche Videoüberwachung nötig, so daß bei einem Alarm vom Überwachungspersonal der Überwachungsbereich auf die Ursache des Alarms hin kontrolliert werden kann, damit nicht bei einem Fehlalarm der Zug gestoppt wird.Light barriers are often used to detect such objects. Although this type of monitoring is not very complex, it has the disadvantage that only objects that interrupt a light beam are recognized, so that the network of light beams must be very narrow. In order to recognize lying people or flat obstacles, the light barriers must be installed very low, which, however, can easily lead to errors in the evaluation, e.g. if There is snow. Additional video surveillance is necessary so that the surveillance area can be checked for the cause of the alarm in the event of an alarm by the surveillance personnel, so that the train is not stopped in the event of a false alarm.

Eine vorteilhaftere Methode ist die Überwachung mit Fernsehkameras und die automatische Auswertung mit einem Videokontroller. Hier werden insbesondere Bewegungen erkannt, so daß ein Fußgänger oder ein Auto im Überwachungsbereich zur Alarmauslösung führt. Da bei dieser Art der Überwachung jeweils zwei zeitlich aufeinanderfolgende Bilder auf Veränderungen überprüft werden, ist die Erkennung eines Objekts von seiner Bewegung abhängig. Ruhende Objekte werden nicht erkannt. Eine Fehlerquelle entsteht durch Veränderungen im Bild, die durch den sich bewegenden Schatten von vorüberziehenden Wolken oder von im Wind bewegten Bäumen entstehen. Bei Dunkelheit ergeben sich Probleme mit den Lichtkegeln von Autoscheinwerfern.A more advantageous method is monitoring with television cameras and automatic evaluation with a video controller. In particular, movements are detected here, so that a pedestrian or a car in the surveillance area triggers the alarm. Since in this type of monitoring two images in succession are checked for changes, the detection of an object depends on its movement. Objects at rest are not recognized. A source of error arises from changes in the image caused by the moving shadow of passing clouds or trees moving in the wind. In the dark there are problems with the light cones of car headlights.

Aufgabe der Erfindung ist es deshalb, eine Überwachungseinrichtung anzugeben, die sowohl ruhende als auch bewegte Objekte im Überwachungsgebiet sicher erkennt und gleichzeitig die Wahrscheinlichkeit von Fehlalarmen herabsetzt.The object of the invention is therefore to provide a monitoring device that is both stationary and also reliably detects moving objects in the surveillance area and at the same time reduces the probability of false alarms.

Diese Aufgabe wird gelöst, indem zur Auswertung zwei Bilder aufgenommen und in je einen Bildspeicher abgelegt werden, wobei eines der Bilder ohne künstliche Beleuchtung aufgenommen wird, während das zweite Bild mit einem Blitz, der gegenüber der Kamera angeordnet ist, wobei die Achse des Strahlungskegels des Blitzes mit der Achse der Kamera einen Winkel bildet, der kleiner als 180° ist, aufgenommen wird. Aus den beiden im Bildspeicher abgelegten Bildern wird nun ein Differenzbild erstellt, das nur Anteile enthält, die aus der Beleuchtung durch den Blitz entstanden sind, während Anteile, die aufgrund des Normallichtes entstanden sind, ausgelöscht werden. Befindet sich ein Objekt im überwachten Gebiet, so ergibt sich im Differenzbild ein Signal im Bereich der Schattenpartien, die auf der dem Blitz abgewandten Seite hinter einem Objekt entstehen. Die Ausdehnung dieser Signale wird ausgewertet. Beim Erkennen eines Schattens wird ein Alarm ausgelöst.This object is achieved by taking two images for evaluation and storing them in an image memory, one of the images being taken without artificial lighting, while the second image with a flash which is arranged opposite the camera, the axis of the radiation cone of the Flash forms an angle with the axis of the camera, which is less than 180 °, is recorded. A difference image is now created from the two images stored in the image memory, which only contains portions which have arisen from the lighting by the flash, while portions which have arisen due to the normal light are extinguished. If there is an object in the monitored area, the difference image results in a signal in the shadow areas that arise behind an object on the side facing away from the flash. The extent of these signals is evaluated. An alarm is triggered when a shadow is detected.

Mit der erfindungsgemäßen Überwachungseinrichtung können dreidimensionale Objekte erkannt werden, wobei es unerheblich ist, ob diese sich bewegen oder ruhen. Durch die Ausblendung des Bildanteils, der durch die Normalbeleuchtung entsteht, werden Veränderungen im Bild, die durch Schatten infolge der Normalbeleuchtung und ähnliches hervorgerufen werden und in bekannten Bildverarbeitungssystemen zu Störungen führen, unterdrückt.With the monitoring device according to the invention, three-dimensional objects can be recognized, it being irrelevant whether these are moving or at rest. By hiding the part of the image that is created by normal lighting, changes in the image that are caused by shadows as a result of normal lighting and the like and that lead to interference in known image processing systems are suppressed.

Kleinere Schatten-Signale, die durch Unebenheiten im Boden entstehen, werden in einer vorteilhaften Ausbildung der Erfindung durch ein planares Tiefpaßfilter ausgefiltert.In an advantageous embodiment of the invention, smaller shadow signals which arise from unevenness in the ground are filtered out by a planar low-pass filter.

Geht man davon aus, daß außerdem Bodenunebenheiten ständig vorhanden sind, kann man sie im System einlernen und abspeichern, so daß bei der Auswertung die Größe und Lage der erkannten Schatten mit den abgespeicherten Daten verglichen werden, so daß die immer vorhandenen Unebenheiten keinen Alarm auslösen.If one assumes that there are also unevenness in the floor, it can be taught in and saved in the system so that the size and position of the detected shadows are compared with the stored data during evaluation so that the unevenness that is always present does not trigger an alarm.

Das zu überwachende Gebiet kann durch eine Maske begrenzt werden, wenn der Erfassungsbereich der Kamera größer ist als das Gebiet, das überwacht werden soll. Die Maske wird dabei elektronisch so festgelegt, daß die ausgeschlossenen Bereiche bei der Auswertung unberücksichtigt bleiben.The area to be monitored can be limited by a mask if the detection area of the camera is larger than the area to be monitored. The mask is electronically determined so that the excluded areas are not taken into account in the evaluation.

Zur Erhöhung der Sicherheit in der Auswertung kann eine zweite Blitzeinrichtung vorgesehen werden, die in einem kurzen Abstand neben der ersten angeordnet ist, so daß zum Beispiel Spurrinnen bei Schnee in Richtung der Ebene, in der die Achse der Kamera-Optik und des Blitz-Strahlungskegels liegen, keine Schatten verursachen. Dabei ist es vorteilhaft, wenn die Achse des zweiten Blitzes einen geringfügig veränderten Winkel zur Kameraachse aufweist.To increase the security in the evaluation, a second flash device can be provided, which is arranged at a short distance next to the first, so that, for example, ruts in the snow in the direction of the plane in which the axis of the camera optics and the flash radiation cone lying, do not cause shadows. It is advantageous if the axis of the second flash has a slightly changed angle to the camera axis.

Zur Erhöhung der Auswertesicherheit trägt auch eine Eingrenzung des Spektralbereiches beim Blitz und vorteilhafterweise auch bei der Kamera bei, da die Störeinflüsse durch diese Ausgrenzung reduziert werden. Einen Bereich von Dunkelrot bis Infrarot können die Fernseh-Kameras mit Halbleitersensoren (CCD-Kameras)noch gut verarbeiten, die Blau-, Grün- und Gelb-Bereiche werden unterdrückt und ein entsprechendes optisches Filter läßt die Szene noch natürlich erscheinen. So können die durch einen begrenzten Spektralbereich ausgelösten Bildsignale einer zentralen Überwachungsstation zur Auswertung zugeführt werden.Limiting the spectral range of the flash and advantageously also of the camera also contributes to increasing the reliability of the evaluation, since the interference is reduced by this exclusion. The TV cameras with semiconductor sensors (CCD cameras) can still process a range from dark red to infrared, the blue, green and yellow areas are suppressed and an appropriate optical filter makes the scene still appear natural. Thus, the image signals triggered by a limited spectral range can be fed to a central monitoring station for evaluation.

Durch eine Öffnung der Blende um 2 bis 3 Stufen wird der Lichtverlust, den das Filter verursacht, ausgeglichen.The light loss caused by the filter is compensated for by opening the diaphragm by 2 to 3 steps.

Im folgenden wird die Erfindung an Hand der Figuren 1 bis 3 näher erläutert.The invention is explained in more detail below with reference to FIGS. 1 to 3.

Es zeigt die Figur 1 ein Blockschaltbild einer erfindungsgemäßen Anordnung, die Figur 2 zeigt die Anordnung von Blitzgerät (nachfolgend als Blitz benannt) und Kamera am Beispiel eines Bahnübergangs und die Figur 3 zeigt den Bildausschnitt mit Sperrbereich und einem dreidimensionalen Objekt.FIG. 1 shows a block diagram of an arrangement according to the invention, FIG. 2 shows the arrangement of flash unit (hereinafter referred to as flash) and camera using the example of a level crossing, and FIG. 3 shows the image section with a restricted area and a three-dimensional object.

Im Blockschaltbild nach Figur 1 ist die Kamera 1 mit der Maskiereinrichtung 2 verbunden. Von dieser Maskiereinrichtung 2 führen Leitungen zum Synch-Separator 3 zur Bildverarbeitungseinheit 12 und zum Schalter S1, der das Signal am Ausgang der Maskiereinrichtung 2 wahlweise mit dem Bildspeicher 6 oder mit dem Bildspeicher 7 verbindet. Der Schalter S1 wird von der Schaltersteuerung 5 angesteuert.In the block diagram according to FIG. 1, the camera 1 is connected to the masking device 2. Cables lead from this masking device 2 to the synch separator 3, to the image processing unit 12 and to the switch S1, which optionally connects the signal at the output of the masking device 2 to the image memory 6 or to the image memory 7. The switch S1 is controlled by the switch control 5.

Der Synch-Separator 3 ist noch mit der Halbbilderkennung 4 verbunden. Diese wiederum hat eine Verbindung zur Schaltersteuerung 5 und zur Blitzansteuerung 8, die mit dem Schalter S2 und mit dem Blitz 9 verbunden ist.The synch separator 3 is still connected to the field recognition 4. This in turn has a connection to the switch control 5 and to the flash control 8, which is connected to the switch S2 and to the flash 9.

Die Bildspeicher 6 und 7 sind außerdem verbunden mit der Differenzschaltung 11, an der die Bildverarbeitungseinheit 12 anschließt. Aus der Bildverarbeitungseinheit 12 führt eine Verbindung zum Alarmgeber 13, der mit einer Alarmausgabeeinheit 14 verbunden ist.The image memories 6 and 7 are also connected to the differential circuit 11, to which the image processing unit 12 connects. A connection leads from the image processing unit 12 to the alarm transmitter 13, which is connected to an alarm output unit 14.

Die Kamera 1 und der Blitz 9 sind am Überwachungsgebiet an gegenüberliegenden Seiten erhöht angeordnet. Eine mögliche Anordnung zeigt Fig. 2a am Beispiel eines Bahnübergangs. Die Anordnung kann bestehen aus der Kamera K und dem Blitz B oder aus der Kamera K und den Blitzen B1 und B2. Im weiteren ist auch eine Anordnung mit mehr als zwei Blitzen möglich, wenn das zu überwachende Gebiet andere Gegebenheiten aufweist, die dies erfordern. Eine Seitenansicht der Anordnung ist in Fig. 2b dargestellt. Fig. 2c zeigt eine Ansicht von oben.The camera 1 and the flash 9 are arranged elevated on opposite sides of the surveillance area. A possible arrangement is shown in FIG. 2a using the example of a level crossing. The arrangement can consist of the camera K and the flash B or of the camera K and the flashes B1 and B2. Furthermore, an arrangement with more than two flashes is also possible if the area to be monitored has other conditions that require this. A side view of the arrangement is shown in Fig. 2b. 2c shows a view from above.

Der Schalter S2 ist bei einem beschrankten Bahnübergang mit der Schranke so verkoppelt, daß er beim Schließen der Schranke die Überwachungseinrichtung aktiviert.The switch S2 is coupled to the barrier at a level crossing so that it activates the monitoring device when the barrier is closed.

Bei Aktivierung der Überwachungseinrichtung wird von der Kamera zunächst ein erstes Halbbild und anschließend ein zweites Halbbild mit Blitzbeleuchtung aufgenommen. Diese Videosignale durchlaufen die Maskiereinrichtung 2, in der alles ausgeblendet wird, was nicht zum zu überwachenden Gebiet gehört. In Figur 3a sind die Teile, die von der Maskiereinrichtung ausgeblendet werden, schraffiert dargestellt, so daß nur das Gebiet zwischen den Schranken übrig bleibt. In der Maskiereinrichtung 2 können aber auch festgestellte Unebenheiten oder die Schienen, die ebenfalls bei der Auswertung störend sein können, ausgeblendet werden.When the monitoring device is activated, the camera first records a first field and then a second field with flash lighting. These video signals pass through the masking device 2, in which everything that does not belong to the area to be monitored is hidden. In Figure 3a, the parts that are masked out by the masking device are shown hatched, so that only the area between the barriers remains. In the masking device 2 However, ascertained bumps or the rails, which can also interfere with the evaluation, can be hidden.

Das in der Maskiereinrichtung 2 manipulierte Bildsignal wird zum einen an den Synch-Separator 3 gelegt, in dem die Synchronisationssignale abgetrennt werden, die dann in der Halbbilderkennung 4 weiterverarbeitet werden. Mit der Verbindung der Maskiereinrichtung 2 zur Bildverarbeitungseinheit 12 werden die durch die Maske ausgeblendeten Bildanteile der Bildverarbeitungseinheit zugeführt, so daß diese Bildanteile bei der Bildauswertung nicht berücksichtigt werden. Weiterhin wird das manipulierte Bildsignal über den Schalter S1 wahlweise an den Bildspeicher 6 oder den Bildspeicher 7 gegeben. Der Schalter S1 wird von der Schaltersteuerung 5 in die jeweils erforderliche Stellung gebracht, wobei von der Halbbilderkennung 4 ein Schaltsignal an die Schaltersteuerung 5 gegeben wird. Die Ansteuerung erfolgt so, daß ein erstes Halbbild im Bildspeicher 6 abgelegt wird. Dieses erste Halbbild wird unter normalen Bedingungen, d.h. ohne Blitz von der Kamera aufgenommen. Beim nächsten Halbbild wird von der Halbbilderkennung 4 wieder ein Schaltsignal an die Schaltersteuerung 5 und die Blitzansteuerung 8 gegeben und das nun generierte Blitzbild im Bildspeicher 7 abgelegt.The manipulated in the masking device 2 image signal is firstly applied to the synch separator 3, in which the synchronization signals are separated, which are then processed in the field recognition 4. With the connection of the masking device 2 to the image processing unit 12, the image portions hidden by the mask are fed to the image processing unit, so that these image portions are not taken into account in the image evaluation. Furthermore, the manipulated image signal is optionally sent to the image memory 6 or the image memory 7 via the switch S1. The switch S1 is brought into the respectively required position by the switch control 5, a switching signal being given by the field recognition 4 to the switch control 5. The control takes place in such a way that a first field is stored in the image memory 6. This first field is under normal conditions, i.e. taken by the camera without flash. In the next field, the field detection 4 again sends a switching signal to the switch control 5 and the flash control 8 and the flash image now generated is stored in the image memory 7.

Die Halbbilderkennung kann nach jedem Halbbild oder jedem Vollbild ein Schaltsignal ausgeben, das in der Schaltersteuerung 5 bzw. in der Blitzansteuerung 8 ausgewertet wird. Die Auswertung kann in vorteilhafter Weise so erfolgen, daß nach Aufnahme des ersten Halbbildes in den Bildspeicher 6 ein Halbbild nicht ausgewertet wird und das nächste Halbbild dann in den Bildspeicher 7 geschrieben wird, wobei bei der Aufnahme dieses Halbbildes der Blitz 9 durch die Blitzsteuerung 8 ausgelöst wurde. Dieses Halbbild enthält nun Bildinformationen, die aufgrund der Normalbeleuchtung erhalten wurden und zusätzlich die Bildinformationen, welche durch den Blitz verursacht wurden.The field detection can output a switching signal after each field or every frame, which is evaluated in the switch control 5 or in the flash control 8. The evaluation can advantageously take place in such a way that after the first Field in the image memory 6, one field is not evaluated and the next field is then written into the image memory 7, the flash 9 being triggered by the flash controller 8 when this field was recorded. This field now contains image information that was obtained due to the normal lighting and additionally the image information that was caused by the flash.

In den Bildspeichern 6 und 7 befinden sich die beiden Halbbilder, die im folgenden in der Differenzschaltung 11 manipuliert werden, indem bildpunktweise jeweils die Differenz aus entsprechenden Bildpunkten des Bildspeichers 6 und des Bildspeichers 7 gebildet wird. Das hieraus entstehende Bild, welches in der Bildverarbeitungseinheit 12 ausgewertet wird, enthält lediglich Bildinformationen, die durch das Licht des Blitzes bewirkt wurden. Bei der Darstellung dieses Bildes auf dem Monitor würde alles weitgehend abgebildet und zu sehen sein, wie auf einem normal aufgenommenen Bild. Es fehlen aber die störenden Fremdlichtquellen, wie Autoscheinwerfer und deren Lichtkegel, und deren Auswirkungen, wie z.B. die durch diese Lichtquellen verursachten Schatten. Es werden auch Schatten unsichtbar, die durch vorüberziehende Wolken oder im Wind wiegende Bäume entstehen und die bei der Bildauswertung mit bekannten Bildaufnahmeverfahren nur mit sehr großem Aufwand oder gar nicht eliminiert werden können.The two fields are located in the image memories 6 and 7 and are subsequently manipulated in the differential circuit 11 by forming the difference from the corresponding image points of the image memory 6 and the image memory 7 pixel by pixel. The resulting image, which is evaluated in the image processing unit 12, only contains image information that was caused by the light of the flash. When displaying this image on the monitor, everything would be largely shown and visible, just like a normal picture. However, the disturbing external light sources, such as car headlights and their light cones, and their effects, such as the shadows caused by these light sources, are missing. Shadows are also invisible, which are caused by passing clouds or trees swaying in the wind and which can only be eliminated with great effort or not at all in the image evaluation using known image recording methods.

Wenn sich nun zum Zeitpunkt der Aufnahme der beiden Halbbilder ein Mensch oder ein Gegenstand im überwachten Bereich befunden hat, entsteht bei der Bildinformation, die nur vom Licht des Blitzes herrührt, ein Schatten an der vom Blitz abgewandten Seite des Objekts, wie es in Figur 3 durch die Fläche S dargestellt ist, der auf das Vorhandensein eines dreidimensionalen Objektes O im Überwachungsgebiet hinweist. Auch die unbeleuchtete Seite des Objekts bleibt schwarz und wird im folgenden ebenfalls als Schatten bezeichnet.If a person or an object is now in the monitored area at the time the two fields are captured, the image information that only results from the light of the flash creates a shadow on the side of the object facing away from the flash, as shown in FIG. 3 is represented by the area S, which indicates the presence of a three-dimensional object O in the surveillance area. The unlit side of the object also remains black and is also referred to as shadow in the following.

Die Bildauswertung kann also in einfachster Weise darin bestehen, einen Schatten, d.h. einen Bereich zu erkennen, dessen Bildwerte Schwarzpegel haben. Wird ein solcher Bereich erkannt, kann durch den Alarmgeber 13 ein Alarm ausgegeben werden, der durch die Alarmausgabeeinheit 14 akkustisch oder optisch angezeigt wird.The simplest way to evaluate the image is to use a shadow, i.e. recognize an area whose image values have black levels. If such an area is recognized, the alarm device 13 can emit an alarm, which is indicated acoustically or optically by the alarm output unit 14.

Die Bildauswertung in der Bildverarbeitungseinheit 12 kann so weit, wie für eine sinnvolle Überwachung nötig, ausgebaut werden. So kann zum Beispiel die Ausdehnung und Form des Bereiches mit Schwarzpegel ausgewertet werden. Auf diese Weise kann eine Alarmauslösung durch beispielsweise eine Zigarettenschachtel unterdrückt werden. Durch eine aufwendigere Bildverarbeitungsanlage können auch Aufhellungen der entstandenen Schatten durch Streulicht berücksichtigt werden.The image evaluation in the image processing unit 12 can be expanded as far as is necessary for meaningful monitoring. For example, the extent and shape of the area can be evaluated with a black level. In this way, an alarm can be suppressed, for example by a cigarette packet. Thanks to a more complex image processing system, brightening of the shadows created by scattered light can also be taken into account.

Bei der Auswertung kann man auch berücksichtigen, daß die Größe des Schattens von der Lage zum Blitz abhängig ist. Ein Objekt, das nahe beim Blitz ist, verursacht einen kleineren Schatten als ein gleich großes Objekt, das weiter entfernt ist, da hier der Anstrahlwinkel flacher ist.When evaluating, one can also take into account that the size of the shadow depends on the position to the flash. An object that is close to the flash creates a smaller shadow than an object of the same size that is further away because the angle of incidence is flatter here.

Dreidimensionale Objekte, die, wie bereits erwähnt, ständig im zu überwachenden Gebiet an gleicher Stelle sind, können durch die Maskiereinrichtung 2 ausgeblendet werden oder sie können in der Bildverarbeitungseinheit 12 von der Auswertung ausgeschlossen werden. Eine Anpassung an verschiedene Einsatzstellen ist hier leicht möglich, indem beim Errichten der Überwachungsanlage der Überwachungsbereich in der oben beschriebenen Weise aufgenommen wird und die dabei entstehenden Schatten werden eingelernt und bleiben bei der Auswertung im Überwachungsgebiet unberücksichtigt.Three-dimensional objects, which, as already mentioned, are constantly in the same area in the area to be monitored, can be masked out by the masking device 2 or they can be excluded from the evaluation in the image processing unit 12. An adaptation to different places of use is easily possible here, in that when the monitoring system is set up, the monitoring area is recorded in the manner described above and the shadows that are created are taught in and are not taken into account in the evaluation in the monitoring area.

Mit Hilfe zweier Blitze - in Figur 2 die Blitze B1 und B2 - können auch schattenbildende Umwelteinflüsse zum Teil unterdrückt werden. So führen durch die Beleuchtung mit zwei Blitzen Spurrinnen, wie sie bei Schnee durch fahrende Autos entstehen, nicht zu einer Schattenbildung. Es ist jedoch zu berücksichtigen, daß der Abstand der beiden Blitze nicht zu groß sein darf, da bei zunehmenden Abstand die Sicherheit beim Erkennen von langen, schmalen und senkrecht stehenden Objekten abnimmt.With the help of two flashes - in Figure 2 the flashes B1 and B2 - even shadow-forming environmental influences can be partially suppressed. The lighting with two flashes of ruts, such as those caused by moving cars in snow, do not lead to shadows. However, it must be taken into account that the distance between the two flashes must not be too large, since with increasing distance the security decreases when recognizing long, narrow and vertical objects.

Wenn die Überwachungskamera des Überwachungssystems gleichzeitig auch zur Überwachung durch ein Überwachungspersonal, also zur Darstellung eines Bildes auf einem Monitor benutzt wird, kann jeweils das Halbbild, das zusätzlich durch Blitz belichtet wurde, durch das im anderen Bildspeicher abgelegte, vorhergehende Halbbild ersetzt werden.If the surveillance camera of the surveillance system is also used for surveillance by surveillance personnel, i.e. for displaying an image on a monitor, the field that was additionally exposed by flash can be replaced by the previous field stored in the other image memory.

Claims (8)

  1. Video monitoring device for the detection of moving and stationary three-dimensional objects on a delimited plane area with the aid of a television camera, characterized in that the device
    - comprises a flash arrangement on the side, opposite the television camera, of the area to be monitored, the axes of flashlight cone and camera optics preferably forming an angle which is smaller than 180°.
    - contains a frame store arrangement in which in each case one frame with triggering of the flash and one frame without triggering of the flash are recorded and stored,
    - contains a differential circuit in which a differential frame is produced from the two frames, which differential frame only contains items of information which have been brought about by the light of the flash,
    - contains an image processing unit which, in the event of a three-dimensional object being present in the monitored area, detects and evaluates the parts on the differential frame which are in shadow and result from the illumination of the object with the flash.
  2. Video monitoring device according to Claim 1, characterized in that the device contains an alarm which is triggered when a three-dimensional object is detected.
  3. Video monitoring device according to Claim 1 or 2, characterized in that the device contains a filter which eliminates small parts of the frame which are in shadow and result from unevennesses inside the area to be monitored.
  4. Video monitoring device according to Claim 1 or 2, characterized in that a memory is provided in which interference shadows which are continuously present are stored, and in that these parts of the frame are fed with stored image signals to the image processing unit for the purpose of interference signal compensation.
  5. Video monitoring device according to one or more of Claims 1 to 4, characterized in that the spectral range of camera and flash is limited by optical filters.
  6. Video monitoring device according to one or more of Claims 1 to 5, characterized in that an electronic mask generator is provided which, during the evaluation, limits the area to be monitored, and in that portions of the frame outside the limits are not evaluated.
  7. Video monitoring device according to one or more of Claims 1 to 6, characterized in that a second flash device is provided in order to increase the reliability of the evaluation.
  8. Video monitoring device according to one or more of Claims 1 to 7, characterized in that the flash devices and the camera are arranged at approximately the same height above the plane of the area to be monitored.
EP90124078A 1990-03-28 1990-12-13 Video control system Expired - Lifetime EP0448803B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT90124078T ATE102726T1 (en) 1990-03-28 1990-12-13 VIDEO CONTROL FACILITIES.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4009912 1990-03-28
DE4009912A DE4009912A1 (en) 1990-03-28 1990-03-28 VIDEO CONTROL DEVICE

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EP0448803A2 EP0448803A2 (en) 1991-10-02
EP0448803A3 EP0448803A3 (en) 1992-09-23
EP0448803B1 true EP0448803B1 (en) 1994-03-09

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AT (1) ATE102726T1 (en)
DE (2) DE4009912A1 (en)

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Publication number Priority date Publication date Assignee Title
DE4436856C2 (en) * 1994-10-16 1998-07-02 Christian Lutz Train braking device
DE19507812A1 (en) * 1995-03-06 1996-09-12 Marinitsch Waldemar Method and device for identifying and locating an object
DE19623524A1 (en) * 1996-06-13 1998-01-02 Pintsch Bamag Ag Monitoring unit for danger area at railway level crossing
DE59912046D1 (en) * 1999-08-27 2005-06-16 Siemens Building Tech Ag Device for room monitoring
DE10044689A1 (en) * 2000-09-08 2002-03-21 Idm Gmbh Infrarot Sensoren Device for monitoring an area of a room
WO2003018402A1 (en) * 2001-08-27 2003-03-06 Edouard Menoud System for detecting foreign bodies on airport runways
ES2260403T3 (en) * 2002-03-11 2006-11-01 Inventio Ag VIDEO SURVEILLANCE SYSTEM THROUGH 3D IMAGE SEMICONDUCTOR SENSOR AND INFRARED LIGHT SOURCE.
JP2006520307A (en) * 2003-03-20 2006-09-07 インベンテイオ・アクテイエンゲゼルシヤフト Elevator area monitoring using 3D sensors
FR2887061B1 (en) * 2005-06-08 2007-08-17 Sagem METHOD FOR ANALYZING A PRESENCE IN A SPACE
DE202007002260U1 (en) * 2007-02-15 2008-06-26 Leuze Electronic Gmbh & Co Kg Optoelectronic device
CN107300722A (en) * 2017-07-18 2017-10-27 孙天宇 A kind of foreign body detection system for airfield runway

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JPH0629707B2 (en) * 1986-10-17 1994-04-20 株式会社日立製作所 Optical cutting line measuring device
FR2606572A1 (en) * 1986-11-07 1988-05-13 Faiveley Ets Method and device for detecting the presence of a body in a predetermined zone

Also Published As

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EP0448803A2 (en) 1991-10-02
DE59004935D1 (en) 1994-04-14
ATE102726T1 (en) 1994-03-15
DE4009912A1 (en) 1991-10-02
EP0448803A3 (en) 1992-09-23

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