JPH0264800A - Remote monitoring system - Google Patents

Abstract

PURPOSE:To obtain the system of a wide applying range by detecting an invader according to a temperature level in a picture which is image-picked up by a thermal camera. CONSTITUTION:A thermal camera 1 image-picks up an area, which is defined as a monitoring subject, and outputs the picture of temperature distribution. Before remote monitor is started, a switcher 2 is changed over to an A-side and the picture of the temperature distribution in the case of no invader is stored in a background memory 3. After the remote monitor is started, the switcher 2 is changed over to a B-side and the picture of the temperature distribution, which is stored in the background memory 3, to be reference is read synchronously with the picture of the temperature distribution from the camera 1. Then, the both pictures of the temperature distribution are inputted to a picture element differential arithmetic circuit 4. In the circuit 4, a differential value in each picture element is inputted to a binarizing circuit 5 and binarized. Next, only the picture of the temperature distribution in the picture element part of a level '1' from the camera 1 is passed through by a switch 6 and an average temperature is operated by an average temperature arithmetic circuit 7. When a temperature is higher than a prescribed temperature, warning is outputted from a warning generating circuit 8. Thus, the system, which can be applied even in darkness, of the wide applying range can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to Which the Invention Pertains) The present invention relates to a remote monitoring system that generates an alarm signal when a person or the like intrudes into a monitoring field of view.

(Prior art) As a monitoring method that monitors a wide three-dimensional area such as a restricted facility and generates an alarm signal when a person or the like intrudes into the area, the brightness level within the screen captured by a television camera is used. A method of detecting an intruder using changes in the number of intruders has been considered. For example, this method detects a temporally moving area by calculating the inter-frame difference of video signals from a television camera, and generates an alarm signal if the moving area is large. However, since this type of method uses the difference in brightness level between images that differ over time, it cannot be used when the difference in brightness level between the background image and the intruder is small, or for monitoring in the dark. There is a problem.

(Objective of the Invention) An object of the present invention is to provide a remote monitoring method having a wide range of applicability by relaxing the restrictions on input video signals as in the above-mentioned remote monitoring method.

(Structure of the Invention) (Characteristics of the Invention and Differences from the Prior Art) The present invention stores a reference temperature distribution image in a monitoring area when there is no intruder etc. in a background memory, and then uses a thermal camera as a primary camera. The most important feature is that it uses a temperature distribution image taken by the camera to detect an intruder based on the temperature level and generates an alarm. The detection method is different from conventional technology that detects an intruder using the difference in brightness level between the background image and the intruder.

(Example) Fig. 1 is a block diagram of a remote monitoring device that implements the method of the present invention. 3 or a switch for switching to the pixel difference calculation circuit 4, and the background memory 3 stores a temperature distribution image that serves as a reference when there is no intruder or the like in the area to be monitored. Further, the pixel difference calculation circuit 4 calculates the difference for each pixel between the background temperature distribution image inputted from the background memory 3 and the temperature distribution image inputted from the thermal camera 1. 5 is a circuit that binarizes the difference signal for each pixel input from the pixel difference calculation circuit 4 using a predetermined threshold; 6 is a circuit that is input from the binarization circuit 5 in the temperature distribution image output from the thermal camera 1; A switch 7 allows only the output level "1" to pass through, and 7 is an arithmetic circuit that calculates the average temperature value of only the portion of the temperature distribution image output from the switch 6.

8 is an alarm generation circuit that is activated when the magnitude of the average temperature value from the calculation circuit 7 is larger than a predetermined value T8.

Next, the operation of the apparatus of this embodiment will be explained using the temperature distribution image shown in FIG.

The thermal camera 1 images the area to be monitored and outputs the temperature distribution image (FIG. 2(b)).

Before starting remote monitoring, first, the switch 2 is set to the A side and a temperature distribution image (FIG. 2(a)) when there is no intruder etc. is stored in the background memory 3.

After starting remote monitoring, set the switch 2 to the B side,
A reference temperature distribution image stored in the background memory 3 is read out in synchronization with the temperature distribution image from the thermal camera 1, and both temperature distribution images are input to the pixel difference calculation circuit 4.

This pixel difference calculation circuit 4 calculates the difference for each pixel between the background temperature distribution image manually input from the background memory 3 and the temperature distribution image input from the thermal camera 1 (Fig. 2(C)). The pixel difference value (absolute value) is input to the binarization circuit 5.

This binarization circuit 5 binarizes the difference signal from the pixel difference calculation circuit 4 using a predetermined binarization threshold Tll, and converts pixels with large difference values to level II I.
11 represents a small pixel at level "0"". Note that the threshold value used here is selected to a value that can remove minute differences caused by temperature fluctuations.

The switch 6 passes only the temperature distribution image of the pixel portion of the level "'-1" outputted from the binarization circuit 5 in the temperature distribution image outputted from the thermal camera 1.

Then, the average temperature calculation circuit 7 calculates the average temperature value T0 of only the portion of the temperature distribution image (FIG. 2(d)) output from the switch 6. If the magnitude of the average temperature value is greater than a predetermined value T, the alarm generating circuit 8 is instructed to be driven. For example, if the drive information output from the average temperature calculation circuit 7 is at the "HIT" level, it is activated, and when it is at the "L" level, it is stopped, and when the average temperature value is T, the drive information is set to "H". H'' level.

The alarm generation circuit 8 generates an alarm when the drive information is at the "HII" level, and stops generating the alarm when the drive information is at the "L" level, based on instructions from the average temperature calculation circuit 7.

FIG. 2 is a diagram explaining the above operation, and FIG. 2(a) is a temperature distribution image of the background image output from the background memory 3, (
b) is a temperature distribution image output from the thermal camera 1;
(C) is a temperature distribution image showing the temperature difference output from the pixel difference calculation circuit 4, and (d) is an extracted temperature distribution image input to the average temperature calculation circuit 7. In other words, by calculating the difference between the temperature distribution image (a) of the background image and the temperature distribution image (b) from the thermal camera 1 for each pixel, an image (c) containing only the difference between the page images is obtained ( In c).

Since the background part has the same level as the image (a) from the background memory 3 and the image (b) from the thermal camera 1, the level is always 11077, and the level occurs only in the part of the image to be extracted.

Note that the average temperature calculation circuit 7 measures the average temperature value T0 only from the extracted image. Therefore, it is possible to determine what the extracted object is based on this temperature and generate a different alarm for each object. Furthermore, since the temperature is extremely high during a fire, it is possible to distinguish between a fire outbreak and an object intrusion based on the average temperature value.

(Effects of the Invention) As explained above, according to the present invention, an intruder, etc. is detected based on the temperature level within the imaged screen captured by a thermal camera, so when the difference in brightness level between the background and the intruder, etc. is small, Of course, it has the advantage of being able to detect intruders and issue an alarm even in the dark.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a device according to an embodiment of the present invention, and FIG.
The figure is a temperature level diagram explaining the operation of FIG. 1. 1...Thermal camera, 2,6...Switcher,
3... Background memory, 4... Pixel difference calculation circuit, 5... Binarization circuit, 7... Average temperature calculation circuit, 8... Alarm generation circuit. Patent applicant: Nippon Telegraph and Telephone Corporation Figure 2, Drawing 1 @Tun, U

Claims (1)

[Claims] A reference temperature distribution image in the monitoring area when there is no intruder, etc. is read out in synchronization with the temperature distribution image obtained from the thermal camera monitoring the intruder, etc., and the difference between both images is calculated for each pixel. The difference image is binarized using a predetermined threshold value, and the average temperature value of only the temperature distribution image of the pixel portion where the difference value is large is calculated, and an alarm is generated when the value is larger than the predetermined value. This remote monitoring method is characterized by: