JP2012070223A - Monitoring camera, monitoring system, and monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for improving detection accuracy of illegal migration of a monitoring camera with reduced costs and without using image processing.SOLUTION: A monitoring camera 2 for monitoring the presence/absence of abnormality is provided with: an imaging part 26 for capturing an image of a subject existing in an imaging range to obtain imaging information; an acceleration sensor 27 which measures acceleration in a direction along a reference axis; RAM 21 for storing the acceleration in the direction along the reference axis in the reference posture of the imaging part 26 as reference information 210; a change amount calculation part 200 which calculates a difference between measurement information 270 obtained by measurement by the acceleration sensor 27 and the reference information 210, thereby calculating change amount information 214 of acceleration in the direction along the reference axis; and a shock determination part 201 and a posture determination part 202 which determine the presence/absence of abnormality in the imaging part 26, according to the change amount information 214 calculated by the change amount calculation part 200.

Description

  The present invention relates to a technique for detecting that a monitoring target is illegally moved.

  There is known a technique for monitoring a site with a monitoring camera without intending to send a monitoring person directly to the site while intending to prevent crime at an entrance of an apartment, a store, an ATM, or the like. And in such a monitoring camera, since it is necessary to image an appropriate imaging range, the imaging direction of the monitoring camera needs to be set appropriately. However, since there is no surveillance staff at the site, there is a risk that a person who intends to commit a crime (hereinafter referred to as a “malicious person”) changes the imaging direction of the surveillance camera before the crime.

  Conventionally, there has been proposed a technique for detecting that the imaging direction of the surveillance camera has been changed and issuing an alarm. For example, Patent Document 1 describes a technique for detecting an unexpected movement of a surveillance camera using an angular velocity sensor. In particular, in Patent Document 1, when the movement of the monitoring camera is small, the detection accuracy is improved by detecting the luminance change of the image captured by the monitoring camera.

JP 2009-239568 A

  However, as the angular velocity sensor described in Patent Document 1, for example, a gyro sensor is assumed. However, the gyro sensor is relatively expensive, and there is a problem that the cost is increased.

  Further, in order to detect a change in luminance of an image, there is a problem that a load on information processing is heavy because image processing on a captured image is necessary. Furthermore, there is also a problem that it cannot be detected when there is no change in luminance in the captured image.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique for reducing costs and improving the detection accuracy of unauthorized movement of a surveillance camera without using image processing.

  In order to solve the above problems, the invention of claim 1 is a monitoring camera for monitoring the presence or absence of an abnormality, imaging means for imaging a subject existing in an imaging range and acquiring imaging information, and a reference axis Acceleration measuring means for measuring the acceleration in the selected direction, storage means for storing the acceleration in the direction along the reference axis in the reference posture of the imaging means as a reference value, and the reference axis measured by the acceleration measuring means. A change amount calculating means for determining a change amount of acceleration in the direction along the reference axis by obtaining a difference between the acceleration along the reference direction and the reference value stored in the storage means; and the change amount calculating means And an abnormality determining unit that determines whether or not there is an abnormality in the imaging unit in accordance with the amount of change obtained by the above.

  The invention according to claim 2 is the surveillance camera according to the invention according to claim 1, wherein the abnormality determination unit is configured to select the imaging unit according to a change amount obtained by the change amount calculation unit and a first threshold value. 1st determination means which determines the presence or absence of abnormality with respect to is provided.

  The invention according to claim 3 is the surveillance camera according to the invention of claim 2, wherein the first determination means obtains an absolute value of the change amount obtained by the change amount calculation means for each of the reference axes. And adding and comparing with the first threshold value.

  The invention according to claim 4 is the surveillance camera according to claim 2, wherein the first determination means obtains a change amount of the composite acceleration based on the change amount obtained by the change amount calculation means. And comparing with the first threshold value.

  The invention according to claim 5 is the surveillance camera according to any one of claims 1 to 4, wherein the abnormality determination means integrates the amount of change obtained by the change amount calculation means during the determination period. And a second determination means for determining the presence or absence of abnormality in the imaging means by comparing the absolute value of the integral value with a second threshold value.

  The invention according to claim 6 is the surveillance camera according to any one of claims 1 to 4, wherein the abnormality determination unit is configured to determine the change amount obtained by the change amount calculation unit during the determination period. Obtaining the absolute value of the average value during the determination period for each reference axis and adding the absolute value of the obtained average value for each of the reference axes for the obtained change amount while acquiring at the sampling cycle of 1 And an average value calculating means for obtaining a determination value, and a third determining means for determining whether there is an abnormality in the imaging means according to the determination value obtained by the average value calculating means and the second threshold value. It is characterized by.

  The invention according to claim 7 is the surveillance camera according to the invention according to claim 6, wherein the average value calculation means is included in the plurality of change amounts acquired in the first sampling period during the determination period. The first sampling period is changed to a second sampling period in accordance with a ratio between a positive change amount and a negative change amount.

  The invention according to claim 8 is the surveillance camera according to any one of claims 1 to 7, wherein the reference axis includes a first reference axis and a second reference axis orthogonal to the first reference axis. It is characterized by including.

  The invention according to claim 9 is the surveillance camera according to the invention according to claim 8, wherein the reference axis further includes a third reference axis orthogonal to both the first reference axis and the second reference axis. It is characterized by that.

  The invention according to claim 10 is the surveillance camera according to any one of claims 1 to 9, wherein the reference axis is along a direction different from the direction along the imaging direction of the imaging means. And

  An eleventh aspect of the present invention is the surveillance camera according to any one of the first to tenth aspects, wherein the reference axis is along a direction different from a direction orthogonal to the imaging direction of the imaging means. And

  According to a twelfth aspect of the present invention, the surveillance camera includes at least one surveillance camera that monitors whether there is an abnormality, and a video reproduction device that reproduces imaging information from the surveillance camera. Imaging means for acquiring imaging information and acceleration measuring means for measuring acceleration in the direction along the reference axis, and the acceleration in the direction along the reference axis in the reference posture of the imaging means is a reference value As a difference between the acceleration in the direction along the reference axis measured by the acceleration measuring means and the reference value stored in the storage means. A change amount calculating means for determining a change amount of acceleration in the direction, and an abnormality determination for determining whether or not there is an abnormality in the imaging means according to the change amount obtained by the change amount calculating means And further comprising a stage.

  The invention according to claim 13 is the monitoring system according to the invention according to claim 12, wherein the video reproduction device outputs an alarm when the abnormality determining means determines that there is an abnormality in the imaging means. And an alarm output means for reproducing the imaging information acquired by the imaging means.

  Further, the invention of claim 14 is a monitoring method for monitoring the presence or absence of an abnormality by a monitoring camera, the step of imaging a subject existing in the imaging range of the monitoring camera and acquiring imaging information, and a reference by an acceleration sensor Measuring the acceleration in the direction along the axis, storing the acceleration in the direction along the reference axis in the reference posture of the monitoring camera as a reference value, and along the reference axis measured by the acceleration sensor In accordance with the step of determining the amount of change in the acceleration along the reference axis by determining the difference between the acceleration in the direction and the reference value stored in the storage means, And determining whether there is an abnormality in the monitoring camera.

  The invention according to any one of claims 1 to 14 measures the acceleration in the direction along the reference axis, stores the acceleration in the direction along the reference axis in the reference posture as a reference value, and the direction along the measured reference axis When the angular velocity sensor is adopted by determining the difference in acceleration in the direction along the reference axis by determining the difference between the acceleration and the reference value and determining the presence or absence of abnormality according to the change Compared to the cost, the processing load can be suppressed because image processing is not used.

It is a figure which shows the structure of the monitoring system in 1st Embodiment. It is a figure which shows the structure of the surveillance camera in 1st Embodiment. It is a figure which shows the reference axis of the surveillance camera in 1st Embodiment. It is a figure which shows the functional block of the surveillance camera in 1st Embodiment with the flow of data. It is a figure which shows the structure of a video reproduction apparatus. It is a flowchart which shows the monitoring method in 1st Embodiment. It is a flowchart which shows the monitoring process of the surveillance camera in 1st Embodiment. It is a figure which illustrates the variation | change_quantity information after sufficient time has passed since the monitoring process was started. It is a figure which shows the change of variation | change_quantity (DELTA) (alpha) _{1 in} the state which the monitoring camera is vibrating in the direction along a 1st reference axis in the determination period. It is a figure which shows the functional block of the surveillance camera in 2nd Embodiment with the flow of data. It is a figure which shows variation | change_quantity (DELTA) (alpha) in 2nd Embodiment. It is a figure which shows the functional block of the surveillance camera in 3rd Embodiment with the flow of data. It is a figure which shows a mode that the variation | change_quantity of an acceleration is acquired for every suitable 1st sampling period during the vibration by disturbance noise. It is a figure which shows a mode that the variation | change_quantity of an acceleration is acquired for every inadequate 1st sampling period during the vibration by disturbance noise. It is a flowchart which shows the attitude | position change monitoring task of the monitoring process in 3rd Embodiment. It is a figure which shows the surveillance camera in 4th Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

<1. First Embodiment>
FIG. 1 is a diagram illustrating a configuration of a monitoring system 1 according to the first embodiment. The monitoring system 1 includes a monitoring camera 2 installed at a site to be monitored and a video reproduction device 3 installed at a monitoring center remote from the site. The monitoring system 1 may be composed of a plurality of monitoring cameras 2 and a plurality of video playback devices 3. Alternatively, the video playback device 3 may be configured to play back video from a plurality of surveillance cameras 2 simultaneously or by switching.

  In the monitoring system 1, the monitoring camera 2 and the video reproduction device 3 are connected in a state where data can be transmitted and received. The connection form between the monitoring camera 2 and the video reproduction apparatus 3 may be a form using a dedicated cable 10 as shown in FIG. 1 or a form via a public network (for example, the Internet). . In addition, wireless communication may be used for part or all of it.

  FIG. 2 is a diagram illustrating a configuration of the monitoring camera 2 according to the first embodiment. The surveillance camera 2 is used as a temporary work area for the CPU 20 that controls data calculation and each component of the surveillance camera 2, a RAM 21 that stores reference information 210, and a program 220 that is executed by the CPU 20. Is read-only ROM 22. In addition, the surveillance camera 2 includes an operation unit 23 that is operated to input information and instructions to the surveillance camera 2, a display unit 24 that displays information by a lamp or LED, and a buzzer 25 that outputs a warning sound. I have. Furthermore, the surveillance camera 2 captures an image of a subject existing in an imaging range and acquires imaging information 9, an acceleration sensor 27 that measures acceleration in directions along three reference axes (described later), and A communication unit 28 that performs data communication with the video reproduction device 3 is provided.

  The so-called three-axis (three reference axes) acceleration sensor 27 has a function of measuring acceleration in the direction along each reference axis.

  FIG. 3 is a diagram illustrating a reference axis of the monitoring camera 2 according to the first embodiment. In the monitoring camera 2 in the first embodiment, the acceleration sensor 27 is monitored so that the first reference axis 81, the second reference axis 82, and the third reference axis 83, which are reference axes, satisfy the relative relationship shown in FIG. Built in the camera 2.

  In brief, in the surveillance camera 2, the first reference axis 81 is an axis in the direction along the imaging direction of the imaging unit 26. At this time, a direction in which the subject is desired from the monitoring camera 2 is a positive direction of the first reference axis 81, and a reverse direction is a negative direction. An axis that is orthogonal to the first reference axis 81 and parallel to the horizontal plane when the first reference axis 81 is arranged parallel to the horizontal plane is referred to as a second reference axis 82. Further, an axis passing through the intersection of the first reference axis 81 and the second reference axis 82 and orthogonal to both the first reference axis 81 and the second reference axis 82 is defined as a third reference axis 83. Note that the direction of the arrow of each reference axis shown in FIG. 3 is “positive”, and the opposite direction of the arrow is “negative”.

  The acceleration sensor 27 creates measurement information 270 according to the measured acceleration and transmits it to the RAM 21. As shown in FIG. 2, the measurement information 270 includes measurement values 271, 272, and 273. In the present embodiment, the measured value of the acceleration along the first reference axis 81 is taken as the measured value 271, the measured value of the acceleration along the second reference axis 82 is taken as the measured value 272, and the third reference axis 83 is taken as the measured value. A measured value of acceleration along the direction is taken as a measured value 273.

  The acceleration sensor 27 performs measurement when the monitoring camera 2 (imaging unit 26) is in the reference posture, and the acceleration in the direction along the reference axis in the reference posture of the image pickup unit 26 is the reference information 210 (reference value). 211, 212, 213) and stored in the RAM 21.

  The reference posture of the monitoring camera 2 is a posture (initial posture) when the operation of the monitoring camera 2 is started, and in this embodiment, when the monitoring camera 2 and the video reproduction device 3 start data communication. The posture of That is, when a signal indicating that communication is started is transmitted in the communication unit 28, the acceleration sensor 27 performs measurement at the timing and creates the reference information 210.

  However, the timing at which the acceleration sensor 27 creates the reference information 210 is not limited to this. For example, an operator who has installed the monitoring camera 2 may input an instruction to operate the operation unit 23 of the monitoring camera 2 and acquire the reference information 210. Alternatively, when the monitoring person visually recognizes the video on the video playback device 3, the monitoring camera 2 confirms that the desired imaging range has been shot, and the video playback device 3 detects the monitoring camera 2 (acceleration sensor 27). Thus, an instruction may be given to create the reference information 210 in the posture.

  FIG. 4 is a diagram illustrating the functional blocks of the monitoring camera 2 according to the first embodiment together with the data flow. The change amount calculation unit 200, the impact determination unit 201, and the posture determination unit 202 illustrated in FIG. 4 are functional blocks that are realized when the CPU 20 executes the program 220.

  The change amount calculation unit 200 stores the acceleration in the direction along the measured reference axis (measurement information 270: measurement values 271, 272, 273) and the RAM 21 each time measurement is performed by the acceleration sensor 27. By obtaining the difference from the reference information 210 (reference values 211, 212, 213), the amount of change in acceleration in the direction along the reference axis is obtained.

More specifically, the amount of change in acceleration in the direction along the first reference axis 81 (hereinafter referred to as “Δα ₁ ”) is obtained by subtracting the reference value 211 from the measured value 271. Similarly, the amount of change in acceleration in the direction along the second reference axis 82 (hereinafter referred to as “Δα ₂ ”) is obtained by subtracting the reference value 212 from the measured value 272. Further, the amount of change in acceleration in the direction along the third reference axis 83 (hereinafter referred to as “Δα ₃ ”) is obtained by subtracting the reference value 213 from the measured value 273.

The values of Δα ₁ , Δα ₂ , and Δα ₃ obtained by the change amount calculation unit 200 are stored in the RAM 21 as change amount information 214. Note that the values of Δα ₁ , Δα ₂ , and Δα ₃ may be “negative values” as well as “0” and “positive values”. Further, the change amount information 214 stores values of Δα ₁ , Δα ₂ , and Δα ₃ obtained at least during the determination period T (for example, 10 seconds). It is possible to refer to at least the amount of change (the past and latest amount of change) during the determination period T.

The impact determination unit 201 refers to the change amount information 214 and executes Expression 1 based on the values of Δα ₁ , Δα ₂ , and Δα ₃ to obtain a determination value Q (first determination value).

Further, the impact determination unit 201 determines whether or not the determined determination value Q is greater than the first threshold value W ₁ . However, | Δα ₁ |, | Δα ₂ |, and | Δα ₃ | are absolute values of Δα ₁ , Δα ₂ , and Δα ₃ , respectively.

That is, the impact determination section 201, in accordance with the change amount determined by the change amount calculation unit 200 and (the amount of change information 214) and the first threshold value W _1, has a function of determining whether there is an abnormality with respect to the imaging unit 26 ing.

More specifically, the impact determination unit 201 obtains the absolute value of the change amount for each reference axis from the change amount obtained by the change amount calculation unit 200, and adds the absolute value of the change amount obtained for each reference axis. When the determination value Q is obtained by performing (Equation 1), the determination value Q is compared with the first threshold value W _1, and the determination value Q is greater than the first threshold value W _1, there is an abnormality in the imaging unit 26. judge.

The determination by the impact determination unit 201 can be performed only by measuring the latest values of Δα ₁ , Δα ₂ , and Δα ₃ , and an abnormality in the imaging unit 26 can be detected in a relatively short time.

  When the impact determination unit 201 determines that there is an abnormality in the imaging unit 26, the impact determination unit 201 transmits the fact to the display unit 24, the buzzer 25, and the communication unit 28 (video playback device 3).

The posture determination unit 202 refers to the change amount information 214 and executes Expression 2 based on the values of Δα ₁ , Δα ₂ , and Δα ₃ during the determination period T to determine a determination value R (second determination value). Ask for.

Further, the posture determining unit 202 obtains the determination value R is equal to or second threshold value W ₂ is greater than.

That is, the posture determination unit 202 obtains an integral value by integrating the change amount obtained by the change amount calculation unit 200 during the decision period T, and determines the absolute value of the integral value as a decision value R (second decision value). And the determination value R and the second threshold value W ₂ are compared to determine whether there is an abnormality in the imaging unit 26.

  When it is determined that there is an abnormality with respect to the imaging unit 26, the posture determination unit 202 transmits the fact to the display unit 24, the buzzer 25, and the communication unit 28 (video playback device 3).

  FIG. 5 is a diagram showing the configuration of the video playback device 3. The video reproduction device 3 is used as a temporary working area for the CPU 30 that controls data calculation and each component included in the video reproduction device 3, and a RAM 31 that stores alarm information 310 transmitted from the monitoring camera 2, A read only ROM 32 for storing a program 320 executed by the CPU 30 and a hard disk 33 for storing and storing the imaging information 9 are provided. Thus, the video reproduction device 3 has a configuration and functions as a general computer that is operated by a monitoring person in the monitoring center.

  The video playback device 3 includes an operation unit 34 that is operated to input information and instructions to the video playback device 3 (monitoring system 1), a display unit 35 that plays back the imaging information 9 and displays it on the screen, and a warning sound. And a communication unit 37 that performs data communication with the monitoring camera 2.

  The above is the description of the configuration and function of the monitoring system 1 in the first embodiment. Next, a monitoring method by the monitoring system 1 will be described.

  FIG. 6 is a flowchart illustrating the monitoring method according to the first embodiment. FIG. 6 mainly shows processing related to the operation of the monitoring camera 2.

  When the monitoring camera 2 is activated, it performs a predetermined initial setting (step S1), and then makes a response request to the video playback device 3 by the communication unit 28 in order to start communication with the video playback device 3. . At this time, it is assumed that the posture of the monitoring camera 2 is determined so that the imaging region of the imaging unit 26 is in an appropriate range and is in the reference posture.

  When a response is returned from the video playback device 3 in response to the response request from the monitoring camera 2 and communication between the monitoring camera 2 and the video playback device 3 is started (Yes in step S2), the communication unit 28 accelerates. An instruction is transmitted to the sensor 27 to acquire the reference information 210. Thereby, the acceleration sensor 27 performs measurement (measurement in the reference posture), and the reference information 210 is created based on the acquired measurement value (step S3).

  When the reference information 210 is stored in the RAM 21, the monitoring camera 2 starts a monitoring process (step S4).

  FIG. 7 is a flowchart showing the monitoring process of the monitoring camera 2 in the first embodiment. The monitoring process refers to a state in which the operation of the monitoring camera 2 is started and the monitoring person is monitoring the presence / absence of an abnormality based on the imaging information 9 from the monitoring camera 2.

  In the monitoring camera 2 in the monitoring process, as shown in FIG. 7, approximately four tasks (imaging task, measurement task, impact monitoring task, and posture change monitoring task) are repeatedly executed simultaneously and in parallel. However, tasks other than these tasks may be executed.

  In the imaging task, the imaging unit 26 performs imaging for each imaging cycle (step S11), and the imaging information 9 acquired by imaging is temporarily stored in the RAM 21, and then transmitted to the video reproduction device 3 (step S12). ) Task. The transmitted imaging information 9 is reproduced on the display unit 35 as necessary in the video reproduction device 3, and it is confirmed whether or not an abnormal situation has been imaged by a monitor.

  The measurement task is a task for measuring acceleration by the acceleration sensor 27. More specifically, measurement information 270 is created in the RAM 21 when the acceleration sensor 27 measures acceleration for each sensing period (step S13).

Next, the change amount calculation unit 200 calculates the amount of change in acceleration for each reference axis based on the reference information 210 and the measurement information 270 (step S14). As a result, the amount of change (Δα ₁ , Δα ₂ , and Δα ₃ ) with respect to the reference posture in the direction along the reference axis is obtained for each reference axis, and the change amount information 214 is created (step S15).

  FIG. 8 is a diagram illustrating change amount information 214 after a sufficient time has elapsed since the monitoring process was started. However, FIG. 8 shows an example in which the current time is “0” and the posture change has occurred in the past (−τ).

  The impact monitoring task is a task in which the impact determination unit 201 determines whether there is an abnormality in the imaging unit 26 (whether an impact has been applied) based on the change amount information 214.

  When an impact is applied to the monitoring camera 2 (imaging unit 26), the posture of the imaging unit 26 changes accordingly, and the imaging range may change, and it may not be possible to capture a desired subject. On the other hand, since the determination by the posture determination unit 202 uses integration during the determination period T, it may take a relatively long time to obtain a determination result.

When a strong impact is applied to the object, the acceleration of the object changes greatly instantaneously, and the amount of change in the acceleration with respect to the reference posture also changes relatively large. Therefore, if this is detected, an abnormality in the imaging unit 26 can be detected in a relatively short time. Therefore, the impact determination unit 201 obtains the determination value Q (first determination value) by executing the above-described Expression 1 (step S16), and the determination value Q is obtained by the first threshold value W ₁ (impact determination) obtained in advance through experiments or the like. It is determined whether it is larger than the threshold value (step S17).

In the example shown in FIG. 8, if the sum of the absolute values of the change amounts (the values of Δα ₁ , Δα ₂ , and Δα ₃ at time “−τ”) when the posture change occurs is larger than the first threshold value W _1. It can be determined at time “−τ” that an impact has been applied.

If the determination value Q is larger than the first threshold value W ₁ (Yes in step S17), the impact determination section 201 transmits a warning to the display unit 24, a buzzer 25 and a communication unit 28. Accordingly, an alarm is output when the LED or the patrol light of the display unit 24 is turned on, and the alarm is also output when the buzzer 25 emits a warning sound (step S18).

  In step S <b> 18, the communication unit 28 transmits and outputs alarm information 310 toward the video reproduction device 3. Receiving this, the video reproduction device 3 outputs an alarm to the display unit 35 and the buzzer 36. At this time, the video reproduction device 3 preferentially reproduces the imaging information 9 from the monitoring camera 2 that transmitted the alarm information 310 on the display unit 35. As described above, in the monitoring system 1, the video playback device 3 that has received the alarm information 310 outputs an alarm and plays back the video of the monitoring camera 2 that has transmitted the alarm information 310, thereby efficiently checking the situation. Can do.

On the other hand, the determination value Q is in the first threshold value W ₁ or less (No in step S17), the impact determination section 201 determines that the impact is not applied, skips step S18, and continues the monitoring process.

  The posture change monitoring task is a task in which the posture determination unit 202 determines whether or not there is an abnormality in the imaging unit 26 (whether or not it has changed from the reference posture) according to the change amount information 214.

As described above, when a relatively large change in acceleration occurs due to a relatively large impact, the impact determination unit 201 can detect an abnormality. However, if the direction of the imaging unit 26 is slowly moved over a long time so that only a relatively small acceleration occurs (so as not to exceed the first threshold value W ₁ ), the impact determination unit 201 cannot detect an abnormality.

However, if the first threshold value W ₁ is lowered in order to improve the detection accuracy of the impact determination unit 201, there is a possibility that erroneous detection frequently occurs due to the influence of disturbance noise. Disturbance noise is temporary and relatively small movement caused by external vibration (earthquake, wind, opening / closing of store shutter, etc.). It is rare for the imaging range of the imaging unit 26 to change greatly due to disturbance noise, and the change is often temporary. Therefore, an acceleration change due to disturbance noise should not be detected as “abnormal”, but if the first threshold value W ₁ is lowered, the impact determination unit 201 erroneously detects an acceleration change due to minute vibration as an abnormality.

Therefore, there is a limit to lowering the first threshold value W ₁ in the monitoring camera 2, and if the Service-to-Self changes the direction of the monitoring camera 2 while keeping the amount of change in acceleration small, the impact determination unit 201 detects it. Without changing the position of the imaging unit 26, the imaging range can be changed.

  However, if the posture changes, the gravitational acceleration applied to the reference axis due to gravity changes. In addition, when the change in posture is not temporary due to disturbance noise but is constant, the change in gravitational acceleration is also constant.

Accordingly, the posture determination unit 202 obtains a determination value R (third determination value) by executing Equation 2 (step S19), and the determination value R is obtained by a second threshold value W ₂ (for posture determination) obtained in advance through experiments or the like. It is determined whether it is larger than (threshold) (step S20).

When determination value R is greater than second threshold value W ₂ (Yes in step S20), posture determination unit 202 transmits an alarm to display unit 24, buzzer 25, and communication unit 28. Accordingly, an alarm is output when the LED or the patrol light of the display unit 24 is turned on, and an alarm is also output when the buzzer 25 emits a warning sound (step S21).

  In step S <b> 21, the communication unit 28 transmits and outputs alarm information 310 toward the video reproduction device 3. Receiving this, the video reproduction device 3 outputs an alarm to the display unit 35 and the buzzer 36. At this time, the video reproduction device 3 preferentially reproduces the imaging information 9 from the monitoring camera 2 that transmitted the alarm information 310 on the display unit 35. As described above, in the monitoring system 1, the video playback device 3 that has received the alarm information 310 outputs an alarm and plays back the video of the monitoring camera 2 that has transmitted the alarm information 310, thereby efficiently checking the situation. Can do.

  In addition, you may comprise so that the warning by the impact determination part 201 and the warning by the attitude | position determination part 202 may be distinguished. Thereby, the monitoring person can distinguish whether the comparatively strong impact was applied to the monitoring camera 2, or the attitude | position of the monitoring camera 2 changed.

On the other hand, when determination value R is equal to or smaller than second threshold value W ₂ (No in step S20), posture determination unit 202 determines that the posture has not changed, skips step S21, and continues the monitoring process.

In the example shown in FIG. 8, the amount of change when the posture change occurs (values of Δα ₁ , Δα ₂ , and Δα ₃ at time “−τ”) does not change after that and is constant. . This is a typical phenomenon when the imaging unit 26 in the reference posture is changed (changed in orientation) to another posture. In such a case, the absolute value of the value obtained by integrating the change amount in the determination period T (corresponding to the area shown by hatching in FIG. 8) is a relatively large value, and thus the determination value R is a relatively large value. Therefore, the posture determination unit 202 can detect “abnormal” in the example shown in FIG.

FIG. 9 is a diagram illustrating a change in the change amount Δα _{1 in} a state where the monitoring camera 2 is vibrating in the direction along the first reference axis 81 during the determination period T. As shown in FIG. 9, when the surveillance camera 2 vibrates due to disturbance noise (vibration), Δα ₁ (amount of change in acceleration) also vibrates.

However, if the vibration is caused by disturbance noise having a relatively small amplitude, the amplitude of the acceleration change amount is also relatively small, and the absolute value of the acceleration change amount does not become a large value. Therefore, since the value of the determination value Q obtained by Expression 1 does not increase, erroneous detection due to disturbance noise is suppressed in the abnormality determination by the impact determination unit 201 (step S17). In other words, the first threshold value W ₁ is set so that the determination value Q does not exceed the first threshold value W ₁ at the amplitude of the disturbance noise.

  Further, the amount of change in acceleration during vibration reciprocates between a positive value and a negative value. Therefore, the integrated value of the amount of change during the determination period T is almost not canceled out every vibration cycle, and thus does not become a large value. Therefore, since the value of the determination value R obtained by Expression 2 does not increase, erroneous detection due to disturbance noise is suppressed in the abnormality determination (step S20) by the posture determination unit 202.

  General vibrations converge after a certain period of time. After the convergence, the monitoring camera 2 normally returns to the reference posture, so the amount of change in acceleration is “0”. Accordingly, when the monitoring camera 2 returns to the reference posture after the vibration has converged, neither the impact determination unit 201 nor the posture determination unit 202 determines “abnormal”.

  Thus, when the monitoring camera 2 vibrates due to disturbance noise (when it is vibrating), the monitoring camera 2 can suppress erroneous detection by detecting this as “abnormal”. Therefore, misreporting due to disturbance noise can be suppressed.

  However, if the position does not return to the reference position after the vibration has converged (if the subsequent position is distorted due to vibration), the position after the vibration has converged (changed position) becomes constant, and the integrated value is not canceled out. The determination value R is a relatively large value. Therefore, the posture determination unit 202 determines “abnormal”. That is, even if the cause is vibration, if the imaging region is constantly changed, there is a possibility that a desired subject is not captured (the imaging range is inappropriate). . In such a case, the posture determination unit 202 can detect “abnormal”.

  By the way, in a situation where the Service-to-Self moves the imaging unit 26 by human power and changes the imaging range, the posture determination unit 202 does not change the posture so that it is not detected, and the shock determination unit 201 does not detect it. It is very difficult to keep moving slowly. In particular, since the surveillance camera 2 is generally fixed to a wall, a ceiling, or the like, even if it is relatively easy to change the orientation by moving the rotating portion (changing the posture), It is difficult to move the surveillance camera 2 fixed on the ceiling or the like without changing the posture. Therefore, the surveillance camera 2 in the present embodiment is sufficiently practical.

  As described above, the monitoring camera 2 according to the first embodiment has the imaging unit 26 that captures the imaging information 9 by imaging the subject existing in the imaging range, and the acceleration that measures the acceleration in the direction along the reference axis. The sensor 27, the RAM 21 that stores the acceleration in the direction along the reference axis in the reference posture of the imaging unit 26 as the reference information 210, and the acceleration along the reference axis measured by the acceleration sensor 27 (measurement information 270) Then, by obtaining a difference from the reference information 210 stored in the RAM 21, a change amount calculation unit 200 for obtaining change information 214 of acceleration in a direction along the reference axis, and a change obtained by the change amount calculation unit 200. By providing an impact determination unit 201 and an attitude determination unit 202 that determine whether there is an abnormality in the imaging unit 26 according to the amount information 214, an angular velocity sensor is provided. The cost can be suppressed as compared with the case of adopting the. Moreover, since it is not necessary to use an image (imaging information 9) in the abnormality determination, the processing load is suppressed.

Further, the impact determination unit 201 determines whether there is an abnormality in the imaging unit 26 according to the change amount information 214 obtained by the change amount calculation unit 200 and the first threshold value W ₁ , so that a large impact is applied. Sometimes an abnormality can be detected in a relatively short time.

Further, the impact determination unit 201 determines the absolute value of the change amount information 214 obtained by the change amount calculation unit 200 for each reference axis, and adds and determines the absolute value of the change amount information 214 obtained for each reference axis. When the value Q is set and the determination value Q is larger than the first threshold value W _1, it is possible to easily perform abnormality determination (impact detection) by determining that there is an abnormality in the imaging unit 26.

In addition, the posture determination unit 202 obtains an integral value by integrating the change amount obtained by the change amount calculation unit 200 during the determination period T, and sets the absolute value of the integral value as the determination value R. By comparing the second threshold value W ₂ with the presence or absence of an abnormality in the imaging unit 26, even if the amount of change in acceleration is small, it can be detected if the posture has changed. Further, erroneous detection due to a temporary posture change due to vibration can be suppressed.

  It should be noted that the video playback device 3 may be configured to store the measurement values (reference information 210 and measurement information 270) of the acceleration sensor 27 executed in the surveillance camera 2 and to perform some calculations and determinations of various information. Good. For example, the reference information 210 regarding the reference posture of the monitoring camera 2 can be transmitted to the video playback device 3 and stored in the video playback device 3. In that case, a functional block corresponding to the change amount calculation unit 200, the impact determination unit 201, and the posture determination unit 202 may be provided in the video reproduction device 3 so as to determine whether there is an abnormality in the imaging unit 26. . When configured in this manner, the burden on the monitoring camera 2 can be reduced, so that the unit price of the monitoring camera 2 can be suppressed. Therefore, when the monitoring system 1 is composed of a relatively large number of monitoring cameras 2, the cost of the entire system can be reduced.

  Further, when the monitoring camera 2 includes a drive unit for panning / tilting the image pickup unit 26, control may be performed so as to return to the reference posture when the posture change is detected.

  In addition, when an impact or a change in posture is detected, the monitoring camera 2 that has detected the impact or the change in posture may be configured to capture an image with another monitoring camera 2.

<2. Second Embodiment>
The determination value obtained for determining whether or not an impact has been applied is not limited to the determination value Q in the first embodiment.

  FIG. 10 is a diagram illustrating functional blocks of the monitoring camera 4 according to the second embodiment together with a data flow. The surveillance camera 4 in the second embodiment is the same as the surveillance camera 2 in the first embodiment except that an impact judgment unit 203 is provided instead of the impact judgment unit 201. In the following description, regarding the monitoring camera 4 in the second embodiment, the same reference numerals are given to the same configurations as those of the monitoring camera 2 in the first embodiment, and description thereof will be omitted as appropriate.

The impact determination unit 203 in the second embodiment obtains a change amount of the composite acceleration (hereinafter referred to as “change amount Δα”) based on the change amount information 214 obtained by the change amount calculation unit 200, and relates to the change amount information 214. the absolute value of the amount of change Δα in the combined acceleration and judgment value S, by comparing the decision value S and the first threshold value W _1, the determination value S when the first is greater than the threshold value W _1, abnormality with respect to the imaging unit 26 Judge that there was.

  FIG. 11 is a diagram illustrating the change amount Δα in the second embodiment.

  The impact determination unit 203 in the second embodiment obtains the determination value S by executing Expression 3 instead of executing Expression 1.

  Also by such a calculation method, it can be detected that an impact has been applied to the imaging unit 26.

<3. Third Embodiment>
In the above-described embodiment, an example in which the integral value during the determination period T of the change amount of acceleration is used to detect the posture change of the imaging unit 26 is not limited to this.

  FIG. 12 is a diagram illustrating functional blocks of the monitoring camera 5 according to the third embodiment together with a data flow. The surveillance camera 5 according to the third embodiment is the same as the first embodiment except that a posture determination unit 204 is provided instead of the posture determination unit 202, and an average value calculation unit 205 is newly provided as a functional block. This is the same as the surveillance camera 2 in the embodiment. In the following description, the monitoring camera 5 in the third embodiment is given the same reference numeral for the same configuration as the monitoring camera 2 in the first embodiment, and the description thereof is omitted as appropriate.

Posture determination unit 204 in the third embodiment, by comparing the judgment value information 215 and the second threshold value W ₂ that is created by the average value calculating unit 205 to be described later, detects a change in the attitude of the imaging unit 26 The image pickup unit 26 has a function of determining whether there is an abnormality.

The average value calculation unit 205 in the third embodiment calculates the acceleration change amounts (Δα ₁ , Δα ₂ , and Δα ₃ ) in the direction along each reference axis stored in the change amount information 214. The reference axis is acquired every predetermined cycle (described later), and the determination value information 215 is created.

  FIG. 13 is a diagram illustrating a state in which the amount of change in acceleration is acquired for each appropriate first sampling period ST1 during vibration due to disturbance noise. FIG. 14 is a diagram illustrating a state in which the amount of change in acceleration is acquired for each inappropriate first sampling period ST1 during vibration due to disturbance noise.

  As shown in FIG. 13 and FIG. 14, the amount of change in acceleration during vibration reciprocates between a positive value and a negative value, but the average value is almost “0”. On the other hand, as already shown in FIG. 8, when the posture changes regardless of vibration, the average value of the amount of change in acceleration is substantially constant, and the value increases according to the degree of the posture change. Therefore, if the average value of the amount of change in acceleration during the determination period T is small, it can be determined that the posture change during that time is due to vibration or the degree of posture change is small (both abnormal No need to detect as.). The posture determination unit 204 according to the third embodiment uses such a principle to detect a posture change without calculating an integral value and suppress erroneous detection due to disturbance noise.

  Here, as shown in FIG. 13, if the first sampling period ST1 is ½ of the vibration period of the acceleration change amount (vibration cycle of disturbance noise), the acceleration change amount is acquired at any phase. Even if it is done, the average value of the obtained acceleration change amount is almost “0”. That is, if the first sampling period ST1 can be determined so as to be about 1/2 of the vibration period of disturbance noise, the average value becomes a relatively small value regardless of the phase.

  On the other hand, as shown in FIG. 14, when the first sampling period ST1 coincides with the vibration period of the disturbance noise, depending on the phase, the average value becomes relatively large due to resonance, and there is a possibility of erroneous detection. Come on. In such a case, it is necessary to change the first sampling period ST1.

  FIG. 15 is a flowchart illustrating an attitude change monitoring task of the monitoring process according to the third embodiment.

  When the monitoring process is started and the posture change monitoring task is started, the average value calculation unit 205 uses the change amount information 214 obtained by the change amount calculation unit 200 in the first sampling period ST1 during the determination period T. The amount of change in acceleration is acquired (step S31).

  When the change amount is acquired, the average value calculation unit 205 performs ratio determination (step S32) according to the acquired change amount. In the ratio determination shown in step S <b> 32, the average value calculation unit 205 determines the positive / negative for each of the change amounts acquired in step S <b> 31, and acquires the number of acquired positive change amounts and the acquired negative change amounts. And the ratio C (number of positive changes / number of negative changes).

Next, the average value calculation unit 205 determines whether the ratio C satisfies Expression 4 according to the third threshold value W ₃ (threshold value for determining the suitability of the first sampling period ST1).

In the present embodiment, the third threshold W ₃ is “3/7”, but the value of the third threshold W ₃ is not limited to this.

  When Expression 4 is not satisfied (No in step S32), the average value calculation unit 205 changes the first sampling period ST1 to the second sampling period ST2 (step S33), and changes in acceleration for each second sampling period ST2 The amount is acquired from the change amount information 214 (step S34).

  In the third embodiment, the second sampling period ST2 is 2/3 of the first sampling period ST1, but is not limited to such a relationship. For example, the second sampling period ST2 may be 3/2 of the first sampling period ST1.

  Furthermore, the average value calculation unit 205 obtains an average value of the acquired acceleration change amounts (acceleration change amounts acquired for each of the first sampling period ST1 or the second sampling period ST2) (step S35). . In the present embodiment, since there are three reference axes, the processes in steps S31 to S35 are executed for each reference axis, and the average value of the change in acceleration is obtained for each reference axis.

  Further, the average value calculation unit 205 calculates the absolute value of the average value for each reference axis obtained in step S35, adds all of them, and stores them in the RAM 21 as determination value information 215.

Determining if the decision value information 215 is created, the posture determining unit 204, the presence or absence of an abnormality with respect to the imaging unit 26 in response to the determination value information 215 and the second threshold value W ₂ (step S36).

When the determination value information 215 is larger than the second threshold value W ₂ (Yes in step S36), the posture determination unit 204 transmits an alarm to the display unit 24, the buzzer 25, and the communication unit 28. Accordingly, an alarm is output when the LED of the display unit 24 is turned on, and an alarm is also output when the buzzer 25 emits a warning sound (step S37).

  In step S <b> 37, the communication unit 28 transmits and outputs the alarm information 310 toward the video reproduction device 3 as in the first embodiment. Receiving this, the video reproduction device 3 outputs an alarm to the display unit 35 and the buzzer 36.

On the other hand, when the determination value information 215 is the second threshold value W ₂ less (No in step S36), the posture determining unit 204 determines that the posture is not changed, without executing the step S37, continues the monitoring process To do.

As described above, the monitoring camera 5 according to the third embodiment acquires the change amount obtained by the change amount calculation unit 200 in the first sampling period ST1 during the determination period T, and acquires the change amount. An average value calculation unit 205 that obtains the absolute value of the average value during the determination period T for each reference axis and calculates the determination value information 215 by adding the absolute value of the average value for each reference axis, and the determination value by and a determining posture determination unit 204 whether there is an abnormality with respect to the imaging unit 26 information 215 and in response to the second threshold value W _2, it is possible to obtain the same effect as the above embodiment. Also, the calculation load can be reduced as compared with the case of obtaining the integral value.

  In addition, the average value calculation unit 205 performs the first sampling cycle according to the ratio of the positive change amount and the negative change amount included in the plurality of change amounts acquired in the first sampling cycle ST1 during the determination period T. By changing ST1 to the second sampling period ST2, it is possible to suppress erroneous detection that occurs because the first sampling period ST1 is inappropriate.

<4. Fourth Embodiment>
In the above-described embodiment, an example in which the acceleration sensor 27 having three reference axes is used has been described. By using the acceleration sensor 27 having three reference axes as described above, the abnormality detection accuracy is improved, but the number of reference axes is not limited to three, and may be one or two. . That is, it is possible to detect an impact and a posture change even by the acceleration sensor 27 in which only one or two reference axes are defined.

  FIG. 16 is a diagram illustrating the surveillance camera 6 according to the fourth embodiment. A direction 84 illustrated in FIG. 16 indicates a direction along the imaging direction of the monitoring camera 6 (imaging unit 26).

  In the surveillance camera 6 in the fourth embodiment, only the first reference axis 85 is defined as the reference axis. Thus, the acceleration sensor 27 according to the fourth embodiment can measure the acceleration in the direction along the first reference axis 85, but is along the direction orthogonal to the first reference axis 85. The direction acceleration cannot be measured.

  Therefore, if the Service-to-Self carefully moves the monitoring camera 6 so that only the acceleration in the direction along the first reference axis 85 does not change, it is not determined as “abnormal”. That is, in the surveillance camera 6 in which only the first reference axis 85 is defined, it is assumed that the detection accuracy is lower than the surveillance cameras 2, 4, and 5 in the above embodiment.

  However, the first reference axis 85 in the fourth embodiment is defined to be along a direction different from the direction 84 along the imaging direction of the monitoring camera 6 and along a direction different from the direction orthogonal to the direction 84. ing. That is, the angle θ formed by the first reference axis 85 and the direction 84 is defined so as to satisfy “0 ° <θ <90 °”.

  In which direction the reference axis (first reference axis 85) of the acceleration sensor 27 is defined cannot be known in appearance. In the monitoring camera 6 according to the fourth embodiment, the first reference axis 85 is along a direction that is different from a direction that is relatively easy to predict as the direction of the reference axis (such as an imaging direction or a direction orthogonal to the imaging direction). It is prescribed.

  Therefore, even if the Service-to-Self carefully moves the monitoring camera 6 so that the acceleration in the direction along the first reference axis 85 does not change, the direction of the first reference axis 85 is unpredictable in the first place. Such movement becomes difficult.

  For example, in the monitoring camera 2 in the first embodiment, as shown in FIG. 3, the first reference axis 81 coincides with the imaging direction. However, since the monitoring camera 2 has three reference axes, any reference axis (first reference axis 81, second reference axis 82 or The acceleration in the direction along the third reference axis 83) changes. Therefore, in the case of having three reference axes, even if the direction that is relatively predictable and the reference axis coincide with each other, this does not reduce the detection accuracy.

  In addition, the directions that are easy to predict are not limited to those shown in the present embodiment, and for example, the vertical direction and the horizontal direction are relatively easy to predict, so only one or two reference axes are provided. When using a non-acceleration sensor 27, it is preferable to pay attention to these directions.

<5. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, part or all of the functional blocks described in the above embodiments may be realized by a dedicated logic circuit. That is, part or all of the configuration described as being realized by software may be realized by hardware.

  Moreover, each process shown in the said embodiment is an illustration to the last, Comprising: It is not limited to such an order and a process. If the same effect can be obtained, the order of the steps and the processing content may be changed as appropriate.

  In addition, the imaging information 9 of the monitoring cameras 2, 4, 5, and 6 may represent moving images or may be still images. Further, it may be a monochrome image or a color image.

1 surveillance system 2, 4, 5, 6 surveillance camera 20 CPU
200 change amount calculation unit 201, 203 impact determination unit 202, 204 posture determination unit 205 average value calculation unit 21 RAM
210 Reference information 214 Change amount information 215 Judgment value information 22 ROM
220 Program 23 Operation unit 24 Display unit 25 Buzzer 26 Imaging unit 27 Acceleration sensor 270 Measurement information 28 Communication unit 3 Video playback device 310 Alarm information 32 ROM
320 Program 35 Display unit 36 Buzzer 37 Communication unit 81, 85 First reference axis 82 Second reference axis 83 Third reference axis 84 direction (direction along imaging direction)
9 Imaging information

Claims (14)

A surveillance camera that monitors for abnormalities,
An imaging unit that captures imaging information by imaging a subject existing in the imaging range;
Acceleration measuring means for measuring acceleration in a direction along the reference axis;
Storage means for storing acceleration in a direction along the reference axis in a reference posture of the imaging means as a reference value;
By calculating the difference between the acceleration in the direction along the reference axis measured by the acceleration measuring means and the reference value stored in the storage means, the amount of change in acceleration in the direction along the reference axis is obtained. A change amount calculation means to be obtained;
An abnormality determining means for determining the presence or absence of an abnormality with respect to the imaging means according to the amount of change obtained by the change amount calculating means;
A surveillance camera comprising: The surveillance camera according to claim 1,
The monitoring camera, wherein the abnormality determination unit includes a first determination unit that determines whether there is an abnormality in the imaging unit according to a change amount obtained by the change amount calculation unit and a first threshold value. The surveillance camera according to claim 2,
The monitoring camera according to claim 1, wherein the first determination unit calculates and adds the absolute value of the change amount obtained by the change amount calculation unit for each reference axis and compares the absolute value with the first threshold value. The surveillance camera according to claim 2,
The monitoring camera according to claim 1, wherein the first determination unit obtains a change amount of the composite acceleration based on the change amount obtained by the change amount calculation unit and compares it with the first threshold value. The surveillance camera according to any one of claims 1 to 4,
The abnormality determining means obtains an integral value by integrating the change amount obtained by the change amount computing means during a judgment period, and compares the absolute value of the integral value with a second threshold value to thereby obtain the imaging means. A surveillance camera, further comprising second determination means for determining whether or not there is an abnormality. The surveillance camera according to any one of claims 1 to 4,
The abnormality determining means includes
While obtaining the change amount obtained by the change amount calculation means at the first sampling period during the determination period, the absolute value of the average value during the determination period is obtained for each reference axis for the obtained change amount. In addition, an average value calculating means for obtaining a determination value by adding the absolute value of the average value for each of the determined reference axes,
Third determination means for determining presence or absence of abnormality with respect to the imaging means in accordance with the determination value obtained by the average value calculation means and a second threshold;
A surveillance camera further comprising: The surveillance camera according to claim 6,
The average value calculating means is configured to determine the first sampling cycle according to a ratio of a positive change amount and a negative change amount included in a plurality of change amounts acquired in the first sampling cycle during the determination period. Is changed to the second sampling period. The surveillance camera according to any one of claims 1 to 7,
The surveillance camera, wherein the reference axis includes a first reference axis and a second reference axis orthogonal to the first reference axis. The surveillance camera according to claim 8,
The surveillance camera, wherein the reference axis further includes a third reference axis that is orthogonal to both the first reference axis and the second reference axis. The surveillance camera according to any one of claims 1 to 9,
The surveillance camera according to claim 1, wherein the reference axis is along a direction different from a direction along an imaging direction of the imaging means. The surveillance camera according to any one of claims 1 to 10,
The surveillance camera according to claim 1, wherein the reference axis is along a direction different from a direction orthogonal to an imaging direction of the imaging means. At least one surveillance camera for monitoring the presence or absence of abnormality;
A video playback device for playing back imaging information from the surveillance camera;
With
The surveillance camera is
An imaging unit that captures imaging information by imaging a subject existing in the imaging range;
Acceleration measuring means for measuring acceleration in a direction along the reference axis;
With
Storage means for storing acceleration in a direction along the reference axis in a reference posture of the imaging means as a reference value;
By calculating the difference between the acceleration in the direction along the reference axis measured by the acceleration measuring means and the reference value stored in the storage means, the amount of change in acceleration in the direction along the reference axis is obtained. A change amount calculation means to be obtained;
An abnormality determining means for determining the presence or absence of an abnormality with respect to the imaging means according to the amount of change obtained by the change amount calculating means;
A monitoring system further comprising: The monitoring system according to claim 12, comprising:
The video playback device
A monitoring system, further comprising an alarm output means for outputting an alarm and reproducing the imaging information acquired by the imaging means when the abnormality determining means determines that there is an abnormality in the imaging means. A monitoring method for monitoring the presence or absence of an abnormality with a monitoring camera,
Imaging a subject existing in the imaging range of the surveillance camera to obtain imaging information;
Measuring acceleration in a direction along the reference axis by an acceleration sensor;
Storing the acceleration in the direction along the reference axis in the reference posture of the monitoring camera as a reference value;
By obtaining the difference between the acceleration in the direction along the reference axis measured by the acceleration sensor and the reference value stored in the storage means, the amount of change in the acceleration in the direction along the reference axis is obtained. Process,
Determining the presence or absence of an abnormality with respect to the monitoring camera according to the obtained change amount;
The monitoring method characterized by having.

Images