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STACKEGÅRD, PER (Skolvägen 14, Sollentuna, S-185 41, SE)
KINNANDER, Per (Grevgatan 19, Stockholm, S-114 53, SE)
STACKEGÅRD, PER (Skolvägen 14, Sollentuna, S-185 41, SE)
| CLAIMS 1. Surveillance system for the surveillance of an area (1), which surveillance system comprises a plurality of sensors (2), characterized in that it comprises a data storage and data processing device (3) that is arranged - to receive signals from the sensors (2), - to store a representation (5) of the area (1), in which representation (5) the area (1) is divided into a plurality of part areas (51), - to determine, based on signals from the sensors (2), status information of each one of the part areas (51), - to determine time-correlated changes of the status information, and - to determine, based on at least two time-separated changes of the status information of a plurality of the part areas (51), data for the sequence of events. 2. System according to claim 1, wherein the data storage and data processing device (3) is arranged to compare said data for the sequence of events with predetermined data for patterns of the sequence of events, and, based on said comparison, identify a pattern of the sequence of events. 3. System according to any one of the preceding claims, wherein the data storage and data processing device (3) is arranged to store position information about at least one protection object (6) in the area (1) and to identify data for the sequence of events comprising a movement of an object toward the protection object (6). 4. System according to any one of the preceding claims, wherein the data storage and data processing device (3) is arranged to identify, upon determination of status information of at least one of the part areas (51) based on signals from at least one first sensor, an object, e.g., a person or a vehicle, and based on signals from at least one second sensor determine a probability for the object constituting a threat to the area (1), a part of the area (1) or a protection object in the area (1). 5. System according to claim 4, wherein the data storage and data processing device (3) is arranged to calculate, by means of position information about a protection object, a protection distance between the identified object and the protection object. 6. System according to any one of the preceding claims, wherein each part area in the representation (5) is adjacent to one or more other part areas. 7. System according to any one of the preceding claims, wherein the area (1) in the representation (5) is divided by a grid and part areas consisting of squares in the grid. |
TECHNICAL FIELD
The present invention relates to a system for the protection of an area, comprising a surveillance system for the surveillance of the area, which surveillance system comprises a plurality of sensors.
BACKGROUND
In security activities and crisis management of areas having objects that are vital for essential public functions, such as power stations and airports, or in areas where sabotage or terrorist actions could cause great damage, it is important that information can be gathered in a reliable way, that it can be presented to actors involved in the security activities so that it forms proper data for rapid decisions, as well as that the same actors can exchange relevant information while maintaining information security and secrecy.
Upon surveillance of certain areas, especially such that comprise greater establishments, such as airports, industries, and power stations, there are often a large number of sensors, usually cameras, distributed in the area. The number of cameras may exceed 500, and the number of displays for the presentation of the camera surveillance may amount to 30 or more. Surveillance by means of such a great number of cameras and displays requires a great number of staff, which is expensive. In addition, the large amount of sensors and great number of staff make it difficult to provide proper data for rapid decisions regarding measures for the protection of the area.
An further difficulty upon surveillance is caused by insufficient reliability of known sensors. I has turned out that sensors that never miss a target give numerous false alarms and that sensors that do give not false alarms miss targets being difficult to detect. Upon outdoor surveillance, another difficulty arises in that different sensors are differently good in different weathers.
SUMMARY
An object of the invention is to improve the possibilities of providing reliable information upon surveillance of an area.
Another object of the invention is to, upon surveillance of an area, improve the possibilities of providing a manageable amount of data from sensor signals.
An additional object of the invention is to, upon surveillance of an area, improve the possibilities of providing information that forms proper data for rapid decisions regarding measures for the protection of the area, or of a part or an establishment in the area.
Said objects are attained by a surveillance system for the surveillance of an area, which surveillance system comprises a plurality of sensors, characterized in that it comprises a data storage and data processing device that is arranged - to receive signals from the sensors,
- to store a representation of the area, in which representation the area is divided into a plurality of part areas,
- to determine, based on signals from the sensors, status information of each one of the part areas, - to determine time-correlated changes of the status information, and
- to determine, based on at least two time- separated changes of the status information of a plurality of the part areas, data for the sequence of events.
The sensors are suitably, in the normal way, set out at different locations in or at the area, and may be of one or more known types, e.g., IR cameras, cameras for visible light, acoustic sensors, microwave sensors, line laser, movable imaging laser, seismic sensors and magnetic sensors.
In the representation, for each part area, there is stored information regarding the position of the part area. Furthermore, the determination of status information of each one of the part areas based on signals from the sensors can be carried out based on a correlation of information about the sensors with the part areas. Such a correlation may comprise information that, for each part area, identifies one or more sensors having coverage of the part area.
According to the invention, the data storage and data processing device is arranged to determine, based on signals from the sensors, status information of each one of the part areas, and determine time-correlated changes of the status information, i.e., changes of the status information correlated with time information. This can be done by determination and storage in the data storage and data processing device of the status information based on instantaneous signals from the sensors, continuous or periodical update of the status information, and based on this update, determination of the time-correlated status information changes. Also these status information changes with their respective time correlations may be stored in the data storage and data processing device.
For instance, the data storage and data processing device may be arranged to record, at a first instant of time, the appearance of a status information change in a first group of part areas, comprising one or more part areas, and, at a second instant of time appearing after the first instant of time, record the appearance of a status information change in a second group of part areas comprising one or more part areas that are not identical with the part areas of the first group of part areas. Based on the status information changes at the first and the second instant of time in the first and second, respectively, group of part areas, data for the sequence of events can be determined. Thus, the invention allows determination of data for the sequence of events based on at least two time-correlated changes of the status information of a plurality of, i.e., at least two, of the part areas. The handling according to the invention of information from a plurality of sensors makes it possible to decrease the dependence on the reliability of individual sensors and improves thereby the possibilities of providing reliable information. For instance, by the invention, a history is created that can be used to estimate the probability of false alarms. As an example, upon the movement of a person or a vehicle through two adjacent part areas, the presence of a status information change determined from sensor signals in one of the part areas and the presence of a status information change in the other part area determined from sensor signals, within a predetermined space of time from the first-mentioned status information change, can give an indication that these sensor signals do not indicate a false alarm.
Furthermore, by the data and information processing according to the invention, which comprises a type of sensor fusion, possibilities are provided for decision- makers upon surveillance and protection of an area to create, from a great number of separate sensor signals, a manageable amount of data that forms proper data for rapid decisions regarding measures for the protection.
Preferably, the data storage and data processing device is arranged to compare said data for the sequence of events with predetermined data for patterns of the sequence of events, and, based on said comparison, identify a pattern of the sequence of events. Such data for patterns of the sequence of events are preferably stored in the data and information processing and may be changes of the status information defined in advance of a plurality of the part areas within a predetermined space of time. For instance, such data for patterns of the sequence of events may correspond to typical antagonistic attack scenarios on protection- worthy objects in the area, accidents, sabotage or other serious events. Thus, said identification of patterns of the sequence of events means a type of pattern detection of, e.g., movements by one or more objects in certain directions in the area, that is considered important to pay attention to for staff using the surveillance system. The pattern detection may also comprise utilization of morphological analysis to mould said data for the sequence of events, e.g., in a way that corresponds to the utilization of morphological analysis for image processing. Thereby, patterns of the sequence of events that are not identical with, but resembles said data for the sequence of events can be identified.
Preferably the data storage and data processing device is arranged to store position information about at least one protection object in the area and to identify data for the sequence of events comprising a movement of an object toward the protection object. The protection object may be a particularly protection- worthy object, such as an important building, nuclear power reactor, etc.
In embodiments of the invention, the data storage and data processing device is arranged to identify, upon determination of status information of at least one of the part areas based on signals from at least one first sensor, an object, e.g., a person or a vehicle, and based on signals from at least one second sensor determine a probability for the object constituting a threat to the area, a part of the area or a protection object in the area. The first sensor may be, e.g., a camera for visible light, the object being identified by automatic recognition known per se in images from the camera. The second sensor may be of another type than the first sensor, e.g., an explosive sensor. Based thereon, the data storage and data processing device can determine whether the object may constitute a threat or not.
The combined sensor types may be any suitable types, e.g., laser beam for movement detection or fire alarm. The sensor signals may also be used in simple logic in the data storage and data processing device by using Boolean operators such as AND, OR, NOT, IF, etc. When a certain chain of events occurs, it may be used to give an alarm or give prediction about coming events according to predetermined conditions. In certain embodiments, the data storage and data processing device may be arranged to calculate, by means of position information about a protection object, a protection distance between the identified object and the protection object. Such a protection distance may be determined based on, among other things, the distance of the object to the protection object, the probability, e.g., determined according to the above, that the object constitutes a threat, a calculated space of time, in turn determined based on above said data for the sequence of events, for the movement of the object to the protection object.
Preferably, each part area in the representation is adjacent to one or more other part areas, whereby the part areas together can be used to create an image of the area, which image may be two-dimensional. The data storage and data processing device may be arranged to store, for each part area, predetermined information about the part area, such as the height of the part area, in absolute numbers or in relation to other part areas. In especially preferred embodiments, the area in the representation is divided by a grid and part areas consist of squares in the grid. Thereby, the part areas can be processed as points or pixels to construct an image of the area. This makes that known image processing techniques can be used for the image to emphasize requested or interesting information.
DESCRIPTION OF THE FIGURES
Embodiments of the invention will be described in more detail below, reference being made to the drawings, in which - Fig. 1 schematically shows an area and a surveillance system according to an embodiment of the invention, and
- Fig. 2 and Fig. 3 show the area in Fig. 1 with respective indicated status information changes in a representation of the area. DETAILED DESCRIPTION
Fig. 1 schematically shows an area 1 and a surveillance system for the surveillance of the area 1. For the simplicity in this description, the area 1 is, in comparison with the most practical applications, strongly simplified. The surveillance system comprises a plurality of sensors 2, in Fig. 1 schematically described as triangles, set out at different locations in or at the area 1. The sensors may be any type suitable for the surveillance of, e.g., one or more of the types exemplified above. The surveillance system also comprises a data storage and data processing device 3 to which the sensors 2 are connected. Each sensor 2 has a respective coverage that is indicated in Fig. 1 by means of a respective line 21.
The data storage and data processing device 3 is arranged to store a representation 5 of the area, in which representation the area is divided into a plurality of part areas 51, and in Fig. 1, these part areas 51 are depicted in the area 1 by dashed lines. The part areas 51 consist of squares 51 in a grid. In many practical cases, it may be suitable to give the squares 51 an extension in the order of 1 x 1 m. The grid may be presented on a display for an operator of the surveillance system and may, on that occasion, occur as a layer (overlay) over a particularly arranged background material, e.g., an aerial photograph having markings about important static objects.
The data storage and data processing device 3 is arranged to store status information of each one of the squares 51, which is provided based on signals from the sensors 2. For this, preceding calibration of the sensors 2 is required that correlates information about the sensors, including their positions and/or coverage, with information about the squares 51, including their positions.
A sensor 2 may have a coverage area 21 that covers one or more squares 51. In the latter case, the calibration preferably comprises an analysis that maps typical signals of the sensor 2 with status information of each square 51 in the coverage area 21. For instance, a camera picture of an object, e.g., a person, can in a known position be correlated with status information of the square in this position, which status information indicates that an object is present in the square 51. Furthermore, for the correlation between sensors and squares, a measuring signal may be used, e.g., a laser pattern, the performance of which in relation to the squares 51 and the sensor signals is recorded.
It should also be noted that a square 51 can be situated within the coverage area 21 of one or more sensors.
In the area 1 , a protection object 6 is situated, i.e., an object that has been determined to be particularly worth to protect, (e.g., a nuclear power reactor). The data storage and data processing device 3 is arranged to store, by means of the representation 5 of the area, position information about the protection object 6.
Here, reference is made to Fig. 2 and Fig. 3. When used for surveillance, the data storage and data processing device 3 is arranged to determine time-correlated changes of the status information of the squares, and, based on at least two time- separated changes of the status information of a plurality of the squares, to determine data for the sequence of events. As an example here, at a first instant of time Tl, status information changes in two squares 51 marked black in Fig. 2 are recorded. At a subsequent second instant of time T2 within a predetermined space of time, status information changes in two other squares 51 marked black in Fig. 3 are recorded.
Based on these status information changes at the first and the second instant of time Tl, T2, data for the sequence of events is determined. The same are determined based on patterns of the sequence of events recorded in the data storage and data processing device 3, which, among other things, comprises the assumption that, if a status information change in one or more squares 51 within a predetermined space of time is followed by a status information change in one or more adjacent squares 51, the presence of an object in the squares can be confirmed, as well as the movement of the object in a direction that is indicated by the time-consecutive status information changes in adjacent squares 51.
In the example in Fig. 2 and Fig. 3, the data storage and data processing device 3 can, since it stores position information about the protection object 6, determine that the movement of the object takes place toward the protection object 6. This information can in turn be used to alarm operators at the surveillance system.
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