EP1410354A2

EP1410354A2 - Device for surveilling an area in a room

Info

Publication number: EP1410354A2
Application number: EP01976199A
Authority: EP
Inventors: Joachim Tiedecke; Michael Weigel
Original assignee: IDM GmbH
Current assignee: IDM GmbH
Priority date: 2000-09-08
Filing date: 2001-09-06
Publication date: 2004-04-21
Also published as: DE10044689A1; WO2002021473A3; WO2002021473A2; AU2001295545A1

Abstract

The invention relates to a device for surveilling an area. Said device comprises an image-recording means, especially a sensor array in the form of a two-dimensional image-producing sensor, and an emitting means emitting electromagnetic waves for illuminating a room to be covered by said image-recording means. The emitting means emits electromagnetic waves in a pulsed manner, and the image-recording means records an image within a defined time frame after the electromagnetic waves have been emitted by the emitting means. The beginning and the duration of the emitted electromagnetic pulses, and the temporal distance between the emitted pulse and the beginning and/or end of the image-recording is pre-determined, thus enabling the distance to be pre-determined between the image-recording means and the intersecting plane (E) to be recorded of the room to be surveilled, and/or the spatial depth (h) of the intersecting plane (serial gating method).

Description

Device for monitoring an area of a room

The present invention relates to a device for monitoring an area, having an image-receiving means, in particular a sensor array in the form of a flat imaging sensor, and an emitting means emitting electromagnetic waves for illuminating a space to be acquired by means of the image-receiving means, the emitting means being electromagnetic Waves are emitted in a pulsed manner and the image-receiving means imprints an image in a specific time window after the electromagnetic waves have been emitted by the transmitting means.

In the industrial world and other areas, the problem arises again and again that a large area must be monitored against access. This

Task cannot always be done with simple sensors like

BESTATIGUNGSKOPIE eg detach light barriers and motion detectors. Difficulties arise especially when a dynamic area is to be monitored and / or a three-dimensional area monitoring is to be implemented.

The object of the present invention is to provide a device for recording and / or monitoring, in particular a three-dimensional space.

This object is achieved according to the invention by means of a device according to the features of claim 1 or a device according to the features of claim 11. Further advantageous embodiments of the devices according to claims 1 or 11 result from subclaims 2 to 10 and 12 to 23.

By means of the device according to claim 1, it is advantageously possible to record individual sectional planes of a room. This is achieved in that a light pulse of a certain duration is emitted to illuminate a room. In accordance with the necessary transit time from the illuminating means to the cutting plane to be exposed, an image is recorded after a certain time by means of an image-capturing means. With this method it is possible to determine a height profile of the three-dimensional space. This principle can also be referred to as serial gating. A fast CMOS array is advantageously used as an imaging sensor. Distortions caused by the wide-angle optics can advantageously be compensated for by image processing. For example, a sensor array, in particular a CCD sensor, can be used as the image-receiving means. Depending on when the imaging points of the sensor array are read out after the light pulse has been emitted, individual sectional planes in the room can thus be viewed in a targeted manner. The integration time determines the vertical extent, i.e. the thickness of each cutting plane. Different sectional planes of the real space can advantageously be recorded one after the other by means of the device. However, it is also possible to record images of the same sectional plane at time intervals in order to determine a change within the sectional plane by comparing these successively recorded images. The comparison of two images taken one after the other can be carried out, for example, by means of image processing by so-called difference image analysis. In particular, differences in the gray values of the images are examined. If there is a significant or not permitted gray value difference between two images, an alarm signal can be triggered, for example. However, other image processing methods can also be used to evaluate the image information obtained. It is also conceivable that three-dimensional objects can be recognized in particular by recording images of several sectional planes within one period and by comparing the images. The device can, for example, trigger an alarm or another event when certain objects are detected that are not allowed to be in the area to be monitored. It is also conceivable that the device monitors the status of a system and recognizes it when liquids and gases escape and likewise initiates suitable measures for alarming and / or problem solving. It is also conceivable that the device automatically starts a certain process after an object enters the area to be monitored. For example, an air conditioning system, music system, etc. can be switched on when a person enters richly. The device can also be used advantageously, for example, to monitor ATMs or rooms. Fixed objects are automatically recognized by the constant comparison of the images, which means that the system gets to know the room through constant comparison and can therefore decide whether new objects have been added to the room. Depending on the speed of movement of the objects or people located in the room to be monitored, they can also be recognized and possibly classified based on their outlines or other identifying features.

Markings which are arranged either in one plane or in different spatial planes or sectional planes can advantageously be used to delimit the region, as a result of which either a two-dimensional or three-dimensional region can be defined. The markings are automatically recognized by the system on the basis of their reflection characteristics and / or contours. As soon as an object moves beyond the area limit, it is recognized by the system and a corresponding event, such as an alarm, is triggered automatically by the system. For example, it is possible for people or objects that are in the area to be provided with an identification mark. The system is thus able to distinguish these objects or people from other objects or people that do not have these identification features. As soon as an object or a person enters the area which is to be monitored and which does not have the corresponding marking, a corresponding event, such as an alarm, can be triggered.

In an advantageous embodiment of the device the room is illuminated by a radiation source, which emits electromagnetic waves in the non-visible area, so that on the one hand disturbances due to fluctuations in daylight are reduced and on the other hand the area cannot be monitored with the naked eye.

The device according to the invention is explained in more detail below by means of drawings.

Show it:

1: the principle of the serial gating method;

2: the principle of difference image analysis;

3: an area limitation for a room to be monitored by means of corner markings;

4: a division of the area to be monitored by means of rectangular markings.

1 shows the basic mode of operation of the device according to claim 1, in which the surroundings or the area to be monitored is illuminated with a light pulse of short duration. Depending on when the imaging points of the sensor array are read out after the light pulse, sectional planes Ei, E ₂ , E ₃ and E ₄ can be viewed in a targeted manner. The integration time, that is to say the time in which the imaging points of the sensor array are charged by incident light, thus determines the vertical extent, that is to say the height h of the planes Ei to E ₄ .

At time Ti, the illuminant emits a short light pulse of a certain duration. At time T ₂ , the illuminated cutting plane is switched on by sensor S for a short period of time (integration time) added. The duration of the integration time starting with the time T ₂ determines the thickness hi of the cut plane Ei.

Subsequently, the sectional plane E _{2 is} monitored by the lamp L emitting a short light pulse at time T ₃ and the sensor S being exposed for a short time starting at time T ₄ , for example by opening the diaphragm or controlling the sensor accordingly. The levels E ₃ and E _{4 can be} recorded accordingly.

Depending on the integration time and the exposure time and the time interval between emitting the light pulse and taking an image by means of the sensor, the cutting plane and its thickness are determined. So it is possible that the cutting planes partially overlap or exactly adjoin each other or that certain cutting planes of the room are not included.

2 shows the comparison of two recorded images Bi and B _{2 of} a sectional plane. The area 1 to be monitored is identified by means of markings 2. Fixed objects are eliminated by the difference value formation (gray value difference). In contrast, the person P, who was not in the area 1 to be monitored in the image B1, is recognized when the difference value is formed. This is shown with the difference ^{value image} G and the person P ^Λ shown in broken lines. Due to the difference formation, objects 0 no longer exist in image G. The area 1 to be monitored is delimited by the markings 2. Due to the overlapping of the images, the device knows from the image Bi or B ₂ , where the limits of the area 1 to be monitored are located. The area marker 2 is shown in Figure G only for clarity. When calculating the difference value, however, it is removed so that it would actually no longer exist in image G.

3 shows a further possibility of identifying an area 1 by means of markings 3. In this case, punctiform markings 3 are only arranged in the corners of the region (polygon) to be monitored as desired. From this, the data processing system of the device calculates the area 1 to be monitored.

As an alternative to the above-described markings, it is possible to divide the area to be monitored by means of line-shaped markings 4 into sub-areas a to f, it being possible to determine whether objects or people are either in the area to be monitored or from part of the area Move the monitored area to another area or out of the area to be monitored.

It goes without saying that the area markings shown in FIGS. 2 to 4 can also be used for the individual sectional planes Ei to E ₄ , that is to say that a plurality of markings in the room can be arranged one above the other in the room, thereby forming an arbitrarily shaped one Area can be defined and monitored. Differently marked or shaped markings for different cutting planes can ensure that markings lying one above the other are reliably recognized. For example, it is also possible to provide markings which are arranged on the floor of the area to be monitored and which are based on their serve as area markings for several cutting planes.

Claims

P a ten tan speech

1.Device for monitoring an area, having an image-receiving means, in particular a sensor array in the form of a flat image-forming sensor, and having an electromagnetic wave transmitting means for illuminating a space to be captured by means of the image-receiving means, the transmitting means emitting electromagnetic waves in a pulsed manner and that image-recording means takes a picture in a certain time window after the electromagnetic waves have been emitted by the transmitting means, since you do not know that the start and the duration of the emitted electromagnetic pulse, as well as the time interval between the emitted pulse and the start and / or the end of the image recording can be specified, and in this way the distance between the image-taking means and the cutting plane (E) to be recorded of the space to be monitored and / or the spatial depth (h) of the cutting plane can be specified (serial-gating method).

2. Device according to claim 1, so that the device takes several pictures of sectional planes (E) of the real space one after the other.

3. Device according to claim 2, so that the device does not show that the device takes the images of the cutting levels to determine differences.

4. Device according to one of claims 1 - 3, since you r ch ge kenn z e i chn e t that a three-dimensional image of the space can be determined by the inclusion of different sectional planes of the real space.

5. Device according to one of claims 1 to 4, d a d u r c h g e k e n e z e i c h n e t that the device in particular periodically picks up a section plane of the real space and compares at least the two last recorded images of this section plane with each other.

6. Apparatus according to claim 5, so that images of all slice planes of the real space are recorded in succession in one period and at least the images of the two last recorded periods are temporarily stored in a memory and compared with one another.

7. Device according to one of the preceding claims, dadu r c h ge k e n n z e i c hn e t that the

Device monitors a 3-dimensional area by means of the determined sectional plane images, wherein in particular the sectional planes can have different area boundaries from one another, which can be assigned to them or ascertainable.

8. Device according to one of the preceding claims, dadur ch ge kenn zei chne t that the depth resolution of a section plane image on the Duty cycle of the lighting source is controlled, in particular the duty cycle being 6.6 nsec for a depth resolution of Im.

9. Device according to one of the preceding claims, since you r c h ge kenn z e i chn e t that the

Time interval between transmission and sensitive switching of the at least one image-recording means specifies the spatial position of the vertical section.

10. The device according to one of claims 1 to 9, since you mark that at least one specific image area of a sectional plane image represents at least one area to be monitored and only differences that are determined in the respective image area for the area monitoring of the device can be considered relevant.

11. Device for monitoring an area, having an image-receiving means, in particular having an electronic camera, a data processing system comparing images taken one after the other to determine differences in the images, so that at least one specific image area is identified each represents an area to be monitored and only differences that are determined in each image area are considered relevant for area monitoring by the device.

12. The apparatus of claim 10 or 11, so that area markings are arranged in the area to be monitored, which are detectable by means of the image processing, and the at least one image area to be evaluated determine.

13. The apparatus of claim 12, so that the area markings stand out in particular from the background of the area to be monitored, particularly in high contrast or by a certain color.

14. The device according to claim 12 or 13, since it is ensured that the area markings are arranged along the boundaries of the area to be monitored.

15. Device according to one of the preceding claims, since you r c h ge kenn z e i chn e t that the

Device carries out an identification and / or classification of objects moving in particular in the area to be monitored and / or determines the direction of movement of objects.

16. The apparatus according to claim 15, since it is clear that object classes exist which contain the objects belonging to the monitoring area and the objects not belonging to the monitoring area.

17. The apparatus of claim 15 or 16, since you r ch ge k e nn z e ichne t that different alarm signals can be generated depending on the determined object type and / or the position and / or the direction of movement and / or the course of movement of an object.

18. Device according to one of claims 15 to 17, d a d u r c h g e k e n n z e i c h n e t that the

Device generates different alarm signals, in particular, if there is at least one certain object moves in the direction of the area to be monitored, and / or at least one specific object is in the immediate vicinity and / or within the area to be monitored.

19. Device according to one of claims 15 to 18, d a d u r c h g e k e n n z e i c h n e t that the

Device generates an alarm signal if at least one specific object behaves atypically for the area to be monitored.

20. Device according to one of the preceding claims, so that the mark is such that the

The area is monitored in that the data processing system compares the gray values or reflectance values of the recorded sectional plane images, which were recorded in particular using the “serial gating method”.

21. Device according to one of the preceding claims, since you rch ge ke nn zeic hn et that the data processing system calculates a reflectance image from its gray values or reflectance values to determine differences between two images taken in succession, the first image (GWBl) without active illumination of the image area and the second image (GWB2) is recorded with active illumination of the image area, and the reflectance image is equal to the difference GWB2 - GWBl of the two images.

22. The apparatus according to claim 21, so that the images are displayed one after the other in time intervals of 1-10000 msec (milliseconds), in particular in time intervals of 10-2000 msec. be taken.

23. Device according to one of the preceding claims, since you r ch ge k e nn z e i c hne t that the

The device has a database in which, in particular, trained image information of the two-dimensional and / or three-dimensional areas to be monitored for different states are stored, this image information for detecting deviations or for monitoring the areas with the currently recorded images or sectional images of the cutting planes be compared.