GB2292628A - Object detection system - Google Patents
Object detection system Download PDFInfo
- Publication number
- GB2292628A GB2292628A GB9417079A GB9417079A GB2292628A GB 2292628 A GB2292628 A GB 2292628A GB 9417079 A GB9417079 A GB 9417079A GB 9417079 A GB9417079 A GB 9417079A GB 2292628 A GB2292628 A GB 2292628A
- Authority
- GB
- United Kingdom
- Prior art keywords
- image
- area
- systems
- placement
- image data
- 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.)
- Granted
Links
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
- G08B13/19602—Image analysis to detect motion of the intruder, e.g. by frame subtraction
-
- 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
- G08B13/19604—Image analysis to detect motion of the intruder, e.g. by frame subtraction involving reference image or background adaptation with time to compensate for changing conditions, e.g. reference image update on detection of light level change
-
- 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
- G08B13/19617—Surveillance camera constructional details
- G08B13/1963—Arrangements allowing camera rotation to change view, e.g. pivoting camera, pan-tilt and zoom [PTZ]
-
- 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
-
- 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
Abstract
The system is for detecting the presence and placement of a foreign object in an area and comprises a first imaging system which serves to detect changes in an image of the area thereby to detect the presence of the foreign object, a second imaging system which serves to detect changes in an image of a ground or background surface at the perimeter of the area thereby to detect the placement of the foreign object and a processor which serves to provide an alarm signal in response to substantially contemporaneous detection by both of the said systems. <IMAGE>
Description
IMPROVEMENTS IN OR RELATING TO
DETECTION SYSTEM
This invention relates to apparatus for the detection of potentially dangerous objects (PDOs) or other foreign objects placed in areas, access to which may be restricted.
An unauthorised entry into an area placed under restricted access (an attack) by its nature is unpredictable, the method of attachment and placement of the PDOs being dependent upon the opportunity presented to an attacker and the layout of the area under attack. An object may also in some circumstances be hidden from view.
It is an object of the present invention to provide apparatus for the reliable detection of the placement and attachment of PDOs with a zero or at least very low false alarm rate.
According to the present invention apparatus for detecting the presence and placement of a foreign object in an area comprises a first imaging system which serves to detect changes in an image of the area thereby to detect the presence of the foreign object, a second imaging system which serves to detect changes in an image of a ground or background surface at the perimeter of the area thereby to detect placement of the foreign object, and a processor which serves to provide an alarm signal in response to substantially contelllpol aneous detection by both of the said svstems.
By arranging that the processor provides an alarm signal only when both of the said systems provide a positive detection signal, the incidence of false alarms is substantially eliminated or at least significantly reduced.
The said first and second systems may each comprise infrared or near infra-red imaging systems.
At least one of the said systems may comprise an infra-red or near infra-red source of illumination, imaging means for producing image data both with and without source illumination, and for providing resultant image data determined in dependence upon the difference therebetween and in accordance with which resultant image data the alarm signal is given.
The said first imaging system may comprise means for scanning the area thereby to produce the said image of part or all of the area.
The means for scanning may comprise a mechanical scanner head which is arranged to rotate through a predetermined arc for scanning purposes and which embodies focusing means effective to focus a strip-like image of the area onto a linear array of detector elements.
The said second imaging system may comprise an image sensing head adapted and arranged to provide a strip-like image of the said ground or background surface typically at the entrance to or on the periphery of the area, which image is arranged to be focused onto a linear array of detector elements.
The source for illumination may comprise a plurality of LED's (Light Emitting Diodes).
The processor may comprise a store for the resultant image data derived from both of the said systems, stored data being used for reference purposes and for comparison with current image data whereby presence and or placement detection is facilitated.
One embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which;
FIGURE 1 is a plan view of a restricted area showing two presence sensor heads,
FIGURE 2 is a side view of the restricted area shown in
Figure 1 showing the sensor heads,
FIGURES 3a and 3b show a side view of a restricted area with a placement detector head and illuminator,
FIGURE 4 is a somewhat schematic system block diagram, and
FIGURE 5 is a state diagram illustrating operation of the system shown in Figure 4.
Referring now to Figure 1, in order to detect the presence of a PDO in a restricted area 1 * a mechanical sensor head 2 is provided which is arranged to rotate thereby to scan a predetermined area 3. As the sensor head 2 rotates, a sector 4 is progressively moved across the area 3 in the direction as indicated by an anow 5. The sensor head 2 is arranged to include a source of illumination comprising a light emitting diode or diodes which illuminates the sector 4 with infra-red or near infrared radiation. An image of the sector illuminated is focused onto a linear image sensor comprising, for example, 128 detector elements thereby to produce data appertaining to a plurality of pixels 6 as shown in Figure 1.The system is such that data appertaining to each pixel is collected with the image illuminated by the LED's and without illumination, a difference signal being producing whereby the effects of ambient illumination are effectively cancelled. Thus it will be appreciated that changing surface effects caused by ambient light can be ignored. It will also be appreciated that an image of the restricted area can be stored in terms of a plurality of pixels whereby a change in one or more of the pixels indicative of the present presence of a foreign body can be detected. The scanning rate may be such as to produce a new image once or twice per second but scanning rates may be increased or decreased as appropriate. The process of regular comparison between a stored image and the current image allows the system to adapt to changes in reflectivity of the area or its contents.If, for example, the area is exposed to the weather, this may be due to drying out, or alternatively the forming of puddles.
The method used is to allow a gradual change of the stored reference image to take place, given the likelihood that changes in reflectivity will usually take much longer than changes in the image due to placement of a PDO. A situation wherein this is not so, such as for example running rain water, can be handled by means of the placement detector described later.
As shown in Figure 2 wherein parts corresponding to those shown in Figure 1 bear the same numerical designations, the sensor head 2 is carried in the end of an assembly 7 which is arranged to hinge or fold so that it can be moved to stow in a protective cover 10. In another example, as well as hinging or folding about a point 11, the rod 7 is arranged to telescope to some extent, but in alternative arrangements it may be arranged to hinge only or to telescope only for the purposes of stowage and or deployment. The arrangement as just before described with reference to Figures 1 and 2 serves to detect the presence of PDOs, the false alarm rate being significantly improved by using a differential detection system whereby the effects of ambient illumination are cancelled. In order, however, to improve the false alarm rate still further, a placement detector is used as will now be described with reference to Figure a and Figure 3b.
Referring now to Figure 3a, the placement detector comprises a detector head 12 and an illuminator 13. The illuminator 13 may compl ise an LED or a plurality of LED's which are used to illuminate a strip region with infra-red or near infrared illumination and the detector head 12 comprises a linear detector array which may. for example, include 128 detectors arranged in a line onto w10ic10 an image of the strip illuminated is projected.Thus it will be appreciated that if an illuminating beam 15 is interrupted by a PDO 16. a shadow "'ill be produced in the region 17 which is detectable by the detector head in predetermined pixels 18 of an image to which the detector head
12 is responsive, which image comprises the illuminated strip beneath the periphery of the vehicle. It will of course be appreciated that the image comprises a plurality of pixels as shown schematically and that other pixels such as pixels 19 will not be affected by the shadow. In addition to the shadow appearing in pixels 18, a further change in contrast or brightness will be observed in pixels 19a, which will be receiving radiation from the object rather than the background, thus providing further collateral information on the placement.
Referring now to Figure 3b, a PDO 16a is situated only in the illuminating beam 15. However, it still produeces a shadow 17a which can be detected in the pixels 18.
In order fully to protect the area, it is apparent that ideally all access points should be protected by a system as just before described with reference to Figure 3a and Figure 3b, but in a practical working system, less comprehensive protection against placement will very probably be sufficient.
Imaging systems suitable for detecting placement and or presence as aforesaid are well known to those skilled in the art and will not be described herein in any great detail, but in order to facilitate a better understanding of the invention one system including processing will now be described with reference to
Figures 4 and 5.
Referring now to Figure 4 for the purpose of presence detection, the sensor head 2 as shown in Figures 1 and 2 may comprise a plurality of LED's 20 which serve to illuminate the restricted area. The segment 4 as shown in Figure 1 which is illuminated, is focused by means of a lens 21 onto a CCD (Charge Couple Device) image sensor 22.Similarly 1) the illuminator 13 and detector head 12 as shown in Figure 3 may be arranged to form part of a placement detector 23 as shown in Figure 4 wherein
LED's 24 are used to illuminate a strip around the periphery of the restricted area, an image of the strip being focused by means of a lens 25 onto a CCD image sensor 26. The LED's 24 and 20 are controlled by LED control units 27 and 28 respectively fed from a processor 37.The images sensed are fed to linear image sensor control units 29 and 30 thereby to produce video signals which are amplified by driver circuits 31 and 32 respectively, the drinker circuit 31 being used to control an analogue to digital converter 33 for the placement signals and an analogue to digital converter 34 for the presence signals. Images appertaining to illuminated and non-illuminated images are stored in a frame store 35 which is fed from the analogue to digital converters 33 and 34.The contents of the frame store are used to produce a reference image in the sensor state memory 36 the processor 29 serving to provide an alarm signal in the presence of a significant difference between a current image in the flame store 35 and a reference image in the sensor state memory 36. The contents of the sensor state memory may be updated as applopriate fom the frame store so as to take account of changes in the image occasioned by drying out for example.Although an excellent false alarm rate is produced with the system as just before described even better performance can be achieved by using further sensors provided by e.g. acoustic detectors and/or magnetic sensor outputs etc which may be used to provide input signals on a line 38. In order to provide control of the system the processor 37 may be controlled via a line 38 which is fed from a user interface 39 and other external systems 40 which are fed via a digital input and output circuit 41 which are coupled via a line 42 to an ignition
ON/OFF switch. The manner in which the system as shown in
Figure 4 operates, is illustrated in a system state diagram as shown in Figure 5 which is self explanatory.Various modifications may be made to the system just before described without departing from the scope of the invention and, for example, it will be appreciated that various types of acoustic sensor may be used in addition to the optical systems described, to provide input signals via the line 38 as shown in Figure 4.
A significant feature of this system is the combination of two detector systems based on similar technology detecting orthogonal phases of an attack. Although an attack is unpredictable, for it to be successful, an object has be to attached within the area and remain attached. The placement detector alone has an inherently high false alarm rate, but by using two systems ie. the placement detector and the presence detector, false alarms are substantially eliminated. Thus in a practical example it is possible for a person to cause the placement detector only to provide an alarm signal.
The presence detector, however, in surveying the restricted area will not under these circumstances detect the presence of a foreign body and so a false alarm signal will not be produced by the system as a whole. Likewise, the presence detector may, in some circumstances, provide a rather lower level of confidence that a PDO has been attached than that required by the user. The level of confidence can be increased by correlating with the output of the placement detector. For example a placement detection together with a presence detection will provide strong support for an alarm condition.
Claims (9)
1. Apparatus for detecting the presence and placement of a foreign object in an area comprising a first imaging system which serves to detect changes in an image of the area thereby to detect the presence of the foreign object, a second imaging system which serves to detect changes in an image of a ground or background surface at the perimeter of the area thereby to detect the placement of the foreign object, and a processor which serves to provide an alarm signal in response to substantially contemporaneous detection by both of the said systems.
2. Apparatus as claimed in Claim l, wherein the said first and second systems each comprise infra-red or near infra-red imaging systems.
3. Apparatus as claimed in Claim 1 and Claim 2, wherein at least one of the said systems comprises an infra-red or near infrared source of illumination, imaging means for producing image data both with and without source illumination, and for providing resultant image data determined in dependence upon the difference therebetween and in accordance with which resultant image data the alarm signal is given.
4. Apparatus as claimed in any preceding claim, wherein the said first imaging system comprises means for scanning the area thereby to produce the said image of part or all of the area.
5. Apparatus as claimed in Claim 4, wherein the means for scanning comprises a mechanical scanner head which is arranged to rotate through a predetermined arc for scanning purposes and which embodies focusing means effective to focus a strip-like image of the area onto a linear allay of detector elements.
6. Apparatus as claimed in any preceding claim, wherein the said second imaging system comprises an image sensing head adapted and arranged to provide a strip-like image of the said ground or background surface which image is arranged to be focused onto a linear array of detector elements.
7. Apparatus as claimed in any preceding claim, wherein the source for illumination comprises a plurality of LED's (Light
Emitting Diodes).
8. Apparatus as claimed in any preceding claim, wherein the processor comprises a store for the resultant image data derived from both of the said systems stored data being used for reference purposes and for comparison with current image data whereby presence and or placement detection is facilitated.
9. Apparatus as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9417079A GB2292628B (en) | 1994-08-24 | 1994-08-24 | Improvements in or relating to detection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9417079A GB2292628B (en) | 1994-08-24 | 1994-08-24 | Improvements in or relating to detection system |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9417079D0 GB9417079D0 (en) | 1994-10-26 |
| GB2292628A true GB2292628A (en) | 1996-02-28 |
| GB2292628B GB2292628B (en) | 1998-03-04 |
Family
ID=10760317
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9417079A Expired - Fee Related GB2292628B (en) | 1994-08-24 | 1994-08-24 | Improvements in or relating to detection system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2292628B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006022594A1 (en) * | 2004-08-27 | 2006-03-02 | Singapore Technologies Dynamics Pte Ltd | Multi-sensor intrusion detection system |
| FR2939942A1 (en) * | 2008-12-17 | 2010-06-18 | Bernard Taillade | PERIMETER SAFETY SYSTEM FOR ACTIVE ANALYSIS OF THE IMAGE OF A VIDEO CAMERA |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3811010A (en) * | 1972-08-16 | 1974-05-14 | Us Navy | Intrusion detection apparatus |
| GB2015223A (en) * | 1978-02-27 | 1979-09-05 | Philips Nv | Surveillance system particularly for detecting the presence of moving persons in an area being monitored |
| EP0356734A2 (en) * | 1988-08-02 | 1990-03-07 | Siemens Aktiengesellschaft | Intruder detection device with television cameras |
-
1994
- 1994-08-24 GB GB9417079A patent/GB2292628B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3811010A (en) * | 1972-08-16 | 1974-05-14 | Us Navy | Intrusion detection apparatus |
| GB2015223A (en) * | 1978-02-27 | 1979-09-05 | Philips Nv | Surveillance system particularly for detecting the presence of moving persons in an area being monitored |
| EP0356734A2 (en) * | 1988-08-02 | 1990-03-07 | Siemens Aktiengesellschaft | Intruder detection device with television cameras |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006022594A1 (en) * | 2004-08-27 | 2006-03-02 | Singapore Technologies Dynamics Pte Ltd | Multi-sensor intrusion detection system |
| FR2939942A1 (en) * | 2008-12-17 | 2010-06-18 | Bernard Taillade | PERIMETER SAFETY SYSTEM FOR ACTIVE ANALYSIS OF THE IMAGE OF A VIDEO CAMERA |
| FR2940000A1 (en) * | 2008-12-17 | 2010-06-18 | Bernard Taillade | PERIMETER SAFETY SYSTEM BY ACTIVE ANALYSIS OF THE IMAGE OF A VIDEO CAMERA |
| WO2010076407A1 (en) * | 2008-12-17 | 2010-07-08 | Bernard Taillade | Perimeter security system for the active analysis of images reflected by a mirror array onto a video camera |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2292628B (en) | 1998-03-04 |
| GB9417079D0 (en) | 1994-10-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20040824 |