JP2011077617A - Moving body imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a processing burden on control by catching a moving body on an imaging surface with high accuracy over the wide range of a photographable field of an imaging apparatus without omission during performing control for catching the moving body on the imaging surface. <P>SOLUTION: Photographed pictures 61a to 61h sequentially photographed on a time base are pictures that are sequentially photographed along the time base, an intruder of the picture 61a moves in subsequent pictures 61b and 61c, and a moving direction of the intruder and predicted positional coordinates of the intruder are determined from differential images of the pictures 62a and 62b photographed in three frames. Pan and tilt values for catching the intruder at the center of a picture are calculated on the basis of the positional coordinates, a zoom value is calculated on the basis of the length of a rectangle (zoom object rectangle) surrounding the differential image of the picture 62b, and the picture 61e is (zoomed up) by a PTZ operation. When a change in the moving direction of the intruder exceeds a prescribed amount in the pictures 61e and 61f, a zoom down operation is performed in order to prevent frame out to advance to a picture 61h. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a moving body imaging apparatus that performs control for capturing a moving body on an imaging surface, and more specifically, an image from a PTZ (Pan: horizontal rotation, Tilt: vertical rotation, Zoom: continuous magnification) camera that takes a moving image. The present invention relates to a moving body imaging apparatus that detects a moving body to be imaged and tracks the detected moving body with a PTZ camera.

Conventionally, many proposals have been made on techniques for capturing and imaging a moving body using a PTZ camera for the purpose of monitoring and the like.
Among these, there is known a system in which a wide-angle fixed camera is provided and a plurality of cameras are used in addition to a PTZ camera that tracks a target moving body. However, this system requires a plurality of cameras and a system for controlling them, leading to an increase in cost. In addition, since the PTZ camera calculates the pan / tilt values used for tracking based on the coordinates of the moving object appearing in the captured image from the wide-angle fixed camera, there is a shift between the coordinate system of the fixed camera and the PTZ camera. It is difficult to maintain accuracy.
When the method of tracking a moving object is adopted, the moving object is extracted to calculate the pan / tilt value. If this process is performed by the optical flow method during the pan / tilt operation, the process is performed. The burden is heavy and may hinder application.

On the other hand, the method of tracking a target moving body using a single PTZ camera can avoid the problems that occur in the above system using a plurality of cameras, so this method has also been proposed in the past. For example, the following patent documents 1 and 2 can be cited.
In Patent Document 1, a captured image plane is divided into regions, a motion is detected from a variation in the feature amount obtained for each region, and the center of gravity of the motion is determined in the horizontal / vertical direction based on information on the region determined to have motion. A monitoring device is shown that calculates a direction and controls the camera so that the center of gravity is at the center of the screen.
Further, in Patent Document 2, an image plane obtained by photographing a monitoring place is divided into areas, and the camera is controlled so that the area where an abnormality has occurred in the image becomes the center of the screen or the distribution of the area is changed. A monitoring system for controlling the angle of view is shown.

JP 2002-369182 A JP-A-7-222137

However, the monitoring device of Patent Document 1 does not solve the zoom operation, so the detection range (monitoring range) of the moving body is limited. In addition, the monitoring system of Patent Document 2 targets an abnormality occurring in an image of a divided area on an imaging surface divided into areas, and does not have a clear intention of tracking a moving object appearing in the imaging surface, and is sufficient for tracking. Performance cannot be obtained.
The present invention has been made in view of the above-described problems of the prior art, and the object thereof is a mobile imaging device that performs control for capturing a mobile object on an imaging surface, and does not leak over a wide range of fields that can be imaged by the imaging device. In addition, the control for capturing the moving body on the imaging surface with high accuracy is performed, and the processing load for the control is not increased.

  The present invention relates to a PTZ camera that takes a moving image, a moving body detection unit that processes a captured image of the PTZ camera and detects a moving body that appears on an imaging surface, and a control that captures the moving body by a PTZ operation of the PTZ camera. A moving body imaging apparatus having a control unit that performs control based on a detection result of a body detection unit, comprising a camera stillness determination unit that determines that a PTZ camera is in a stationary state, wherein the control unit includes the camera stillness determination unit Pan / tilt corresponding to the control target position estimated based on the angle of view of the PTZ camera and the position information of the moving object to be captured detected on the imaging surface by the moving object detecting means when the stationary state is determined by And the zoom value corresponding to the control target angle of view determined based on the difference image of the moving object to be captured detected on the imaging surface by the moving object detection means. And performing Z operations.

  According to the present invention, it is possible to capture a moving object with high accuracy near the center of the imaging surface without leaking over a wide range of fields that can be imaged by the imaging apparatus, and without increasing the processing burden on control. can do.

It is the schematic which shows one structural example of the intruder (mobile body) monitoring system comprised by applying the mobile body imaging device of this invention. It is a block diagram which shows schematic structure of the server terminal which is an element of an intruder monitoring system (FIG. 1). It is a figure explaining the determination area at the time of performing stillness determination of a PTZ camera based on a picked-up image. It is a figure explaining the pan / tilt operation to the position estimated from the motion of the intruder (moving body) appearing on the imaging surface. It is a figure explaining PTZ control operation accompanied by zoom operation according to the difference in the moving speed of an intruder (moving body). It is a figure explaining PTZ control operation accompanied by zoom operation according to a movement (change of a moving direction, etc.) of an intruder (moving body). It is a figure explaining PTZ control operation when a plurality of intruders (moving body) appear on the image pick-up surface. It is a flowchart of PTZ control at the time of catching an intruder (moving body) with a PTZ camera. It is a figure which shows the subsequence of pan / tilt operation (step S104) to the fixed wide angle of the flow (FIG. 8) of PTZ control. It is a figure which shows the subsequence of the camera still determination (step S107) of the flow (FIG. 8) of PTZ control. It is a figure which shows the subsequence of the intruder detection (step S109) of the flow (FIG. 8) of PTZ control. It is a figure which shows the subsequence of PTZ value calculation (step S111) of the flow (FIG. 8) of PTZ control.

Hereinafter, an embodiment of a moving body imaging apparatus according to the present invention will be described by taking an intruder (moving body) monitoring system as an example.
"Overview of intruder monitoring system configuration"
FIG. 1 is a schematic diagram showing a configuration example of an intruder monitoring system according to this embodiment.
As shown in FIG. 1, the intruder monitoring system 100 configures a system by connecting a PTZ camera 101 (hereinafter also simply referred to as “camera”) 101, a server terminal 103, and a display terminal 105 via a network 107. .
The PTZ camera 101 is a camera that determines a shooting area in a monitoring place (shooting field) by a PTZ (Pan Tilt Zoom) operation and picks up a moving image thereof. A single camera can basically constitute a system suitable for the intended purpose, but a plurality of cameras may be provided corresponding to a plurality of shooting fields.
The display terminal 105 is a monitor terminal that displays an image picked up by the PTZ camera 101. Basically, even a single device can constitute a system that meets the intended purpose. Can be a monitor attached to the server terminal 103 to be described later.

The server terminal 103 is a terminal that manages the entire intruder monitoring system 100. The PTZ operation (described in detail later) is performed on the PTZ camera 101 that manages the PTZ camera 101 and the display terminal 105 and captures the intruder in the shooting field on the imaging surface. Control operations such as the above are performed.
FIG. 2 is a block diagram illustrating a schematic configuration of the server terminal 103.
As illustrated in FIG. 2, the server terminal 103 includes a control unit 201, an image reception unit 202 that operates under the control of the control unit 201, an image recording unit 203, a communication interface unit 204, a camera stillness determination unit 205, and intruder detection. Each unit includes a unit 206, a PTZ value calculation unit 207, and a PTZ command transmission unit 208, and a bus 209 used for data exchange among the above-described units.

  The control unit 201 controls the entire server terminal 103, takes in an image captured by the camera 101 through the communication interface unit 204, and performs control / processing necessary for performing a PTZ operation described later (in FIGS. 8 to 13 described later). As a means for performing (flow) and the like, although not shown, a CPU (Central Processing Unit), a RAM (Random Access Memory) for temporarily storing programs and data necessary for processing of the CPU, and a CPU are driven. The computer includes a storage unit such as a ROM (Read Only Memory) that stores a program or the like for executing operations and processes.

The communication interface unit 204 captures an image captured by the camera 101 (FIG. 1) and is sent via the network 107, and receives an input interface passed to the image receiving unit 202 and a PTZ command passed from the PTZ command sending unit 208. This is an output interface to be sent to the camera 101 via.
The image receiving unit 202 is a unit that converts the captured image passed from the communication interface unit 204 into data that can be used for image processing (processing by the intruder detection unit 206 and the like) performed later.
The image recording unit 203 is a unit that records the image data converted by the image receiving unit 202 so that it can be taken out in units of frames.

The camera stillness determination unit 205 is a means for determining the stillness of the PTZ camera based on the captured image. Note that the stillness determination will be described in detail later with reference to FIG.
The intruder detection unit 206 is a means for performing processing for detecting an intruder (moving body) appearing on the imaging surface using a processing method such as an inter-frame difference method based on the captured image. The intruder detection will be described in detail later with reference to FIG.
The PTZ value calculation unit 207 is a unit that calculates a PTZ value used for a PTZ operation for capturing an intruder in the imaging field on the imaging surface. The method for calculating the PTZ value will be described in detail later with reference to FIGS.
The PTZ command sending unit 208 is a unit that instructs the communication interface unit 204 to transmit a PTZ command to the camera 101 using the PTZ value calculated by the PTZ value calculating unit 207.

  As an example of the configuration of the server terminal 103, the image receiving unit 202, the image recording unit 203, the camera stationary determination unit 205, the intruder detection unit 206, the PTZ value calculation unit 207, and the PTZ command transmission, which are components of the server terminal 103. Each processing unit of the unit 208 can be implemented by a dedicated circuit as in the example shown in FIG. 2, but the computer that configures the control unit 201 operates a program for realizing the functions of these processing units. It is possible to configure the means by performing the above-described method.

“Generating PTZ values”
The server terminal 103 according to the present embodiment, when performing control for capturing an intruder (moving body) on the imaging surface by PTZ operation, does not leak the intruder over a wide range of fields that can be captured by the camera with high accuracy (with high resolution). ) And prevent the processing burden on this operation from increasing. For this purpose, the following operations (1) to (4) are performed.
(1) An intruder (moving body) is detected based on a captured image when the camera is stationary. That is, the intruder detection unit 206 does not operate during the PTZ operation, and performs intruder detection by confirming the stillness determination result by the camera stillness determination unit 205. That is, the processing load can be reduced by avoiding intruder detection during the PTZ operation.
(2) The zoom value is adjusted according to the moving speed obtained based on the detection result of the intruder (moving body). That is, when the moving speed is high, the probability of frame-out increases, so zooming down (to make a wide angle), and when the moving speed is slow, the probability of frame-out decreases and zoom-in is performed.
(3) The angle of view is enlarged on the condition that the moving direction obtained based on the detection result of the intruder (moving body) has changed beyond a predetermined amount. That is, when the moving direction is changed, the probability of frame-out increases, so the zoom is reduced (wide angle).
(4) The zoom value is adjusted when a plurality of intruders (moving bodies) appear on the imaging surface. That is, the zoom-down is performed in order to photograph all the intruders (wide angle).

Next, a processing means (method) for performing the operations (1) to (4) will be described in detail based on a photographed image example.
<Camera stillness determination>
The camera stillness determination unit 205 performs camera stillness determination based on the captured image.
The camera stillness determination unit 205 detects a temporal change in the captured image of the camera 101, and determines whether the camera 101 is still or whether the camera is in a PTZ operation depending on whether or not the detection result is changed. Specifically, the difference between the frames of the captured image is obtained, and the size (area) of the obtained difference image is compared with a predetermined determination reference value. judge.

However, in the detection method based on the inter-frame difference described above, when the captured image captures a moving object, it may be erroneously determined that the PTZ operation is being performed even if the camera 101 is stationary. Therefore, in this embodiment, an area that does not include a moving body that causes erroneous determination on the imaging screen is selected as a determination area.
FIG. 3 is a diagram for explaining a determination area selected on the imaging screen. In the embodiment shown in the figure, an area on the screen of the imaging area 301 where a moving object that causes a false determination does not enter is defined as an outer peripheral portion of the imaging surface 301. Since the camera 101 tries to catch the intruder (moving body) near the center of the imaging screen by the PTZ operation, the possibility that the intruder (moving body) exists in the determination area defined in the peripheral portion is low. Therefore, erroneous determination can be avoided by setting this area as a determination area for camera stillness determination by the inter-frame difference method.

<Intruder detection>
The intruder detection unit 206 performs intruder detection based on the photographed image.
The intruder detection unit 206 detects a change in the captured image of the camera 101 with time, and detects the presence or absence of an intruder depending on whether or not the image has changed. At the time of detection, it is a condition that the camera 101 is stationary, and an intruder detection operation is performed according to the determination result of the camera stationary determination unit 205.
Specifically, the inter-frame difference of the captured image is obtained, and the presence or absence of an intruder is determined based on the obtained difference image. Also, when there is an intruder, the position of the intruder, or the position of the intruder and the movement of the intruder (movement direction, speed) based on the difference image for use in <PTZ value calculation> described later. Are stored in the image recording unit 203 as detection results.

The intruder detection method will be described with reference to FIG. 4 for explaining the pan / tilt operation to the position predicted from the movement of the intruder (moving body) appearing on the imaging screen.
In FIG. 4, screens 41 a, 41 b, and 41 c in the shooting area 401 are screens that are sequentially shot along the time axis when the camera 101 is stationary. The intruder (moving body) that has entered the screen 41a is moving in the center direction of the screen as shown in the screens 41b and 41c. When these inter-frame differences are taken, the screens 42a and 42b representing the difference images are displayed. can get. Note that the screens 41a, 41b, and 41c of the photographed images shown in FIG. 4 are not shown in the figure, but actually there is a background, and if the difference is taken, only the intruder (moving body) as in the screens 42a and 42b. It becomes the image of.
Noise components are included in the images that appear on the screens 42a and 42b that have taken the difference. Since the noise component is smaller than the image of the intruder to be processed normally, the noise is removed with a predetermined threshold value, and only the intruder to be processed is left. In the present embodiment, as shown in the screens 42a and 42b representing images obtained by inter-frame differences, a rectangle surrounding the difference image recognized as being from the same intruder is obtained as an intruder extraction result (described later in FIG. 11). Intruder detection processing flow).

In addition, the movement (moving direction, speed) of the intruder can be obtained as follows. That is, a rectangle (rectangles shown on the screens 42a and 42b) surrounding the difference image is obtained according to the above-described procedure using the captured images for three frames in time series. Here, the rectangular center point obtained from each difference image is regarded as a coordinate value representing the position of the intruder, and this value is obtained. The change in the coordinate of the center point of the obtained rectangle (change in the difference image from the screen 42a to the screen 42b) is represented by the change in the coordinate value of the center point indicated by the arrow on the screen 43 in the conceptual diagram of FIG. By this variation, the moving direction and speed can be obtained. In addition, it is not limited to the example using the above-described captured images for three frames, images of three frames or more may be used, and if the intruder image of each frame can be separated in the inter-frame difference image even for two frames, The moving direction can be obtained from the change in the center of gravity position of each intruder image.
The rectangle surrounding the same intruder or the movement (moving direction, speed) of the intruder in the difference image obtained as described above is used for calculating the PTZ value as described in <PTZ value calculation> below.

<Calculation of PTZ value>
When the camera 101 is initially moved, the camera 101 starts a shooting operation with an initial setting that is directed to the center of a shootable field, for example, at the maximum angle of view, and remains stationary until the intruder detection unit 206 detects the intruder. Thereafter, when the intruder detection unit 206 detects the intruder, the PTZ operation of the camera 101 is performed so that the detected intruder is caught near the center of the imaging screen.
This PTZ operation allows the intruder to stay on the screen for a long time without going out of frame. In addition, when a plurality of intruders are detected, these intruders are made to fit on the screen without being out of frame. Specifically, it is necessary for the intruder detection unit 206 to detect the intruder by the method described in <Intruder detection> above, and to catch the intruder near the center of the imaging screen based on the obtained detection result. A pan / tilt value is calculated, a change in an image representing the speed of the intruder, a zoom value necessary for a plurality of intruders is calculated, and the camera 101 is controlled using the calculated PTZ value as a control target value. Manipulate.
The PTZ value is calculated by the PTZ value calculating unit 207, and the calculated PTZ value is transmitted to the camera 101 by the PTZ command sending unit 208 via the communication interface unit 204 as a PTZ command.

Next, calculation methods of “pan / tilt value” and “zoom value” calculated by the PTZ value calculation unit 207 will be described.
“Pan / Tilt value”
The calculated pan (P) and tilt (T) values represent the deviation of the position (coordinates) of the intruder detected by the intruder detection unit 206 with respect to the center (coordinates) of the captured image as a variation of the respective coordinate values. The variation is converted into a pan / tilt value as an operation amount, that is, a pan / tilt operation amount for capturing an intruder near the center of the imaging screen. In this conversion, the angle of view and the number of pixels of the captured image (screen) are factors. Note that the angle of view represents the range that can be taken by the camera, and the zoom (Z) value can be represented by the angle of view.
The pan (P) value and tilt (T) value correspond to the x coordinate, horizontal angle of view, and the number of horizontal pixels in the former, and the latter corresponds to the y coordinate, vertical angle of view, and the number of vertical pixels. ,does not change. Accordingly, only an example of calculating the pan (P) value will be described below.

The obtained pan value (: PAN) is calculated based on the following formula (1).
(target_x−center_x): PAN = ImageNX: horizontal_angle (1)
In the above formula (1),
target_x: Intruder's x coordinate (current position coordinate) to be captured at the center of the screen after panning
center_x: x coordinate of the center of the captured image
ImageNX: Number of pixels in the horizontal direction of the captured image (screen)
horizontal_angle: Horizontal angle of view The above center_x and ImageNX are based on the configuration conditions of the camera 101 and the server terminal 103, and are invariable if there is no change in settings or the like. On the other hand, target_x is a variable because it changes with the movement of the intruder, and horizontal_angle also changes the angle of view corresponding to the movement of the intruder, as will be described later.
When the calculated pan value is equal to or less than a predetermined threshold value, the operation can be stabilized by avoiding the operation target.

Here, an embodiment will be described in which predicted values in consideration of the intruder's movement are used for the intruder's x, y coordinates (current position coordinates) used as target_x (target_y).
In the above <intruder detection>, as described with reference to FIG. 4, the rectangle surrounding the same intruder in the difference image (the rectangle shown in the screens 42a and 42b in FIG. 4) is obtained as the detection result of the intruder. The center point of this rectangle can be obtained as a coordinate value representing the position of the intruder and used as target_x (target_y).
However, since the center point of the rectangle of the difference image does not coincide with the true image center point of the intruder, target_x (target_y) that gives a result closer to the true image center point is predicted.

This prediction is performed based on the position and movement of the intruder detected by the intruder detection unit 206. That is, if there is an intruder who is moving after the pan / tilt operation based on the center point of the rectangular image of the difference image representing the position of the intruder described in <Intruder detection> and the movement (moving direction and speed) of the intruder. By finding the predicted position. If the example of FIG. 4 shown above is drawn, the position of the intruder obtained as the center point of the rectangle of the difference image (the rectangle shown in the screens 42a and 42b in FIG. 4) and two difference images obtained from three frames will be shown. This is based on the moving direction and speed of the intruder represented by the variation of the coordinate value of the rectangular center point (arrow shown on the screen 43 in FIG. 4).
The position prediction performed based on the position, moving direction, and speed of the intruder takes into account the time required for the PTZ operation confirmed by tests and simulations, for example, and determines the image center point of the intruder after the pan / tilt operation by linear prediction. Prediction is performed (the prediction result from the screen 43 in FIG. 4 is indicated by a white arrow and a prediction center point added on the screen 44).
The position predicted in this way (predicted center point) is set to target_x (target_y) and applied to the equation (1), and the control operation is performed with the obtained pan / tilt value, whereby the position close to the true image center point Can capture intruders.

“Zoom value”
The zoom adjustment is performed so that the intruder does not go out of the frame, stays on the screen for a long time, and captures with high resolution. Here, the following three operation modes are used.
First, when one intruder is captured, the angle of view (zoom value) is adjusted according to the moving speed of the intruder. Basically, if the moving speed is high, the zoom is reduced. Zoom in if you are late.
The second is a form in which when one intruder is captured, the angle of view is enlarged, that is, zoomed down, on the condition that the moving direction of the intruder has changed beyond a predetermined amount.
The third is a mode in which when a plurality of intruders are detected, the angle of view is adjusted so that these intruders are not out of frame but fit on the screen.

The zoom value is determined by how many pixels on the image the intruder wants to take.
The desired zoom value (: ZOOM) is calculated based on the following equation (2).
now_size: now_zoom = after_size: ZOOM ... Formula (2)
In the above formula (2),
now_size: Pixel size of the intruder currently taking
now_zoom: Current zoom value (view angle)
after_size: Pixel size of the intruder trying to take after zooming
ZOOM: desired zoom value When calculating the zoom value according to the above equation (2), the pixel size of the intruder to be photographed is expressed as 1 / x of the image size (unchangeable unless setting is changed).
A zoom value for performing zoom adjustment in the first to third embodiments is calculated by the above equation (2), and the camera 101 is operated using the calculated zoom value as a control target value.

Here, with reference to FIG. 5, an embodiment when performing zoom adjustment in the first mode will be described.
FIG. 5 is a diagram for explaining the zoom operation of the PTZ camera in which the setting of the zoom value is changed according to the difference in moving speed of the intruder (moving body). FIG. 5A shows the normal speed, and FIG. Indicates a faster case.
In FIG. 5, screens 51 a and 51 b in the shooting area 501 are screens that are sequentially shot along the time axis when the camera 101 is stationary.
Since the intruder (moving body) that has entered the screen 51a is moving on the next screen 51b, a difference image on the screen 52 is obtained when these inter-frame differences are taken. Here, when a rectangle surrounding an image recognized as being caused by the same intruder from the difference image (hereinafter referred to as “zoom target rectangle”) is obtained, the vertical and horizontal lengths of the zoom target rectangle are proportional to the moving speed in the vertical and horizontal directions. It becomes the length. Therefore, the longer one of the vertical and horizontal lengths of the zoom target rectangle is selected as the pixel size of the intruder currently shooting, and the zoom value (: ZOOM) obtained based on the above equation (2) is calculated. When the calculated zoom value or the size of the rectangle surrounding the difference is equal to or smaller than a predetermined threshold value, the operation is stabilized so that the operation is not performed.

In the case of the normal speed in FIG. 5A, since the intruder (moving body) that has entered the screen 51a has not moved so much on the next screen 51b, it becomes a slightly elongated rectangle to be zoomed. Select a length and shift it to be 1 / x the image size. In the illustrated example, since 1 / x is approximately 2/3, the zoom is increased (the angle of view is reduced).
On the other hand, in the case of the higher speed in FIG. 5B, the intruder (moving body) that has entered the screen 51a has moved considerably in the horizontal direction on the next screen 51b, and thus becomes a horizontally elongated rectangle to be zoomed. , Select the horizontal length and shift it to be 1 / x the image size. In the example shown in the figure, 1 / x is approximately 2/3, so that the zoom is reduced (the angle of view is enlarged).
As described above, a zoom value that enables zoom-up / down is calculated according to the moving speed of the intruder, and the calculated zoom value is sent as a control target value to the camera 101 as a PTZ command.

Here, an example when performing zoom adjustment in the second mode will be described with reference to FIG.
FIG. 6 is a diagram for explaining the zoom operation of the PTZ camera that changes the zoom value according to the movement of the intruder (moving body).
In FIG. 6, screens 61a, 61b, 61c, 61d, 61e, 61f, 61g, and 61h in the shooting area 601 are screens that are sequentially shot along the time axis. However, the screens 61d and 61g indicate that the screens are meaningless in that the PTZ operation is being performed, intruder detection is not performed, and a new zoom value is not obtained. Is a screen when the camera 101 used for intruder detection is stationary. The zoom operations on the screens 61a to 61e show the case where the zoom adjustment is performed in the first form described in FIG. 5, and the zoom operations on the screens 61e to 61h show the case where the zoom adjustment is performed in the second form. Is.

Since the intruder (moving body) that has entered the screen 61a is moving on the subsequent screens 61b and 61c, a difference image on the screens 62a and 62b is obtained when these inter-frame differences are taken. Depending on the moving direction and conditions of the intruder from the difference image for three frames, the position coordinates of the intruder are obtained by using the position prediction, and the pan / tilt value is calculated as described above. The movement of the intruder such as the moving direction and the position coordinates (including the predicted value) of the intruder obtained at this time are stored for use in subsequent processing.
In the illustrated example, it is determined that the execution condition of the PTZ operation is satisfied from the movement of the intruder on the screen 62b, and the calculation is performed based on the vertical length of the rectangle (zoom target rectangle) surrounding the difference image on this screen. A zoom-up operation (see FIG. 5A) is performed according to the zoom value, and a screen 61e is obtained.

When the PTZ operation accompanied by the zoom-up operation is finished and the camera 101 is stationary, the intruder is detected based on the difference image that can obtain the inter-frame difference between the screens 61e and 61f as described above.
Among the detection results at this time, the zoom operation (see FIG. 5) according to the zoom value calculated based on the length of the rectangle (zoom target rectangle) surrounding the difference image is an example shown in the screen 62c in FIG. Since the horizontal length of the rectangle is the target set value, the zoom operation is not necessary.
However, if it is determined from the detection result at this time that the moving direction of the intruder has changed beyond a predetermined amount, zoom adjustment is performed in the second mode. That is, a zoom value for enlarging the view angle, that is, zooming down is determined as a control target value.

The change in the direction of movement of the intruder is obtained as follows. First, a rectangle surrounding the difference image shown on the screen 62c is obtained in the same manner as the above-described intruder motion detection, the center point (coordinates) of this rectangle is obtained, and the center point of the rectangle obtained from the previous difference image as a target. From the change from (coordinates), the current moving direction of the intruder can be obtained. Next, it is confirmed whether or not the change in the movement direction of the current intruder obtained and the change in the movement direction of the intruder previously obtained and stored exceed a predetermined amount.
As a result, if the moving direction of the intruder has changed beyond a predetermined amount, it is considered that the intruder has suddenly changed the moving direction. In this case, since the possibility that the intruder who captures the frame out increases, a value smaller than the current zoom value by a predetermined amount is set as the control target value to prevent the frame out.
In the example shown on the screen 62c in FIG. 6, the moving direction (indicated by an arrow in the figure) of the intruder obtained on the screen 62b is suddenly changed as shown on the screen 62c. A zoom-down operation is performed according to the zoom value, and a screen 61h is obtained.

In addition, an embodiment when performing zoom adjustment in the third mode will be described with reference to FIG.
FIG. 7 is a diagram for explaining the zoom operation of the PTZ camera that changes the zoom value so that when a plurality of intruders (moving bodies) are detected, these intruders do not go out of the frame and fit on the screen. .
In FIG. 7, screens 71a, 71b, 71c, and 71d in the shooting area 701 are screens that are sequentially shot along the time axis. However, the screen 71c indicates that the screen is meaningless in that the PTZ operation is being performed, intruder detection is not performed, and a new zoom value is not obtained. It is a screen when the camera 101 used for intruder detection is stationary.
Since the intruder (moving body) that has entered the screen 71a is moving, when the inter-frame difference from the next screen 71b is taken, a difference image on the screen 72 is obtained and the presence of a plurality of intruders is recognized ( (See the intruder detection process flow of FIG. 11 described later).

For the difference images of a plurality of intruders, the above-described processing for calculating the zoom value based on the rectangle surrounding the intruder difference image is performed when only one intruder exists on the screen. I can't catch everything.
Therefore, the zoom value that fits on the screen after the zoom operation by all of the intruders is calculated as the control target value.
The calculation method obtains a rectangle surrounding all the difference images of a plurality of intruders on the screen 72 of FIG. 7 as a zoom target rectangle, and based on this rectangle, the calculation method and the first method shown in the “pan / tilt value” described above. The method of calculating the zoom value shown in the first form (see FIG. 5) is applied.
In this way, by calculating the PTZ value as the control target value and performing the PTZ operation of the camera 101, it is possible to capture all the intruders on the screen. In the example shown in FIG. 7, a pan / tilt operation is performed with the center of the rectangle enclosing the difference obtained on the screen 72 as the center of the screen, and a zoom operation for capturing the zoom target rectangle with a predetermined size is performed to obtain the screen 71d. It is done.

"PTZ operation"
Next, processing / control procedures when the camera 101 is operated for PTZ will be described with reference to FIGS.
When the PTZ camera 101 and the server terminal 103 of the intruder monitoring system 100 (FIG. 1) are powered on, the connection of the network 107 is confirmed, and the system is ready for operation, the control flow of FIG. 8 is started. The
In this control flow, at the time of activation, first, the upper limit value of the PTZ value is acquired from the camera 101 as an operation condition unique to the camera (step S101). The upper limit value of the PTZ value is used in order to avoid erroneous operation and failure by operating the camera within the range of operating conditions.
Next, an initial value (monitoring start position) of the PTZ value is set (step S102). For example, the shooting operation is started with a setting that is directed to the center of the field that can be shot at the maximum angle of view.

After the camera 101 starts to shoot, check the detection result of the intruder detection (step S109 described later) of the photographed image, and whether the intruder is not detected for a predetermined time (predetermined as a design condition). It is confirmed whether or not (step S103). This step S103 is confirmed by examining the result of the intruder detection at the start of photographing or after detecting the intruder.
If the intruder is not detected in step S103 for a predetermined time or more, that is, the intruder is started several times while the timer that first obtains the detection result by detecting the intruder in the captured image described later and starts. If no intruder is detected even after the detection (step S103-YES), pan / tilt operation to fix the wide angle is performed (step S104).

The state obtained by the pan / tilt operation to fix the wide angle in step S104 is a state in which the intruder waits for capturing the intruder on the screen for the first time from the state where the intruder is not on the screen, and is usually the same as the initial state. Then, the PTZ operation of the camera 101 is performed according to the setting in step S102 at the start of shooting.
That is, as shown in the sub-sequence of FIG. 9 showing the processing procedure of pan / tilt operation to fix the wide angle, the initial value (monitoring start position) of the PTZ value is set (step S201), and the set PTZ value is set to the PTZ command. The sending unit 208 sends a PTZ command as a PTZ command to the camera 101 via the communication interface unit 204 (step S202). After sending the command, whether or not a PTZ operation is being performed to manage the operation of this processing / control flow is determined. The PTZ operation flag shown is turned ON to exit this subsequence.

After performing the pan / tilt operation to fix the wide angle (step S104), or when the predetermined time has not elapsed (NO in step S103) even if the intruder is not detected, the image receiving unit 202 Then, the captured image of the camera 101 is received via the communication interface unit 204 (step S105).
Next, processing such as intruder detection is performed on the received photographed image. As processing for confirming the execution condition of this processing, first, whether or not the PTZ operation is being performed is confirmed by ON / OFF of the PTZ operation flag ( Step S106).
In step S106, the PTZ operation flag is confirmed. If the flag is OFF (step S106-NO), intruder detection is immediately performed (step S109). Intruder detection will be described in detail later.

On the other hand, the PTZ operation flag is confirmed, and if the flag is ON (step S106-YES), camera stillness determination is performed (step S107). This step is performed to confirm that the camera 101 is in a stationary state by the server terminal 103 itself and to execute image processing for detecting an intruder on the shooting screen. The camera stillness determination is performed based on the interframe difference obtained by the camera stillness determination unit 205 for the outer peripheral area of the captured image (see the description of <Camera Stillness Determination> above).
The processing procedure of camera stillness determination is performed according to the subsequence of FIG. According to the sequence of FIG. 10, first, the inter-frame difference in the outer peripheral area of the currently received captured image to be processed is obtained (step S301).

Next, the size (area) of the obtained difference image is compared with a predetermined determination reference value, and it is determined whether or not it is equal to or less than the reference value (step S302).
Here, when it is below the reference value (step S302-YES), it is determined that the camera is stationary, and the PTZ operation flag turned on by the pan / tilt operation (FIG. 9) to fix the wide angle is turned off (step S302). S303), this subsequence is exited. If the reference value is exceeded (step S302-NO), it is determined that the PTZ operation is being performed, and the PTZ operation flag turned ON by the pan / tilt operation to fix the wide angle (FIG. 9) is left as it is. Exit this subsequence.
After passing through the camera stillness determination sub-sequence, whether or not the PTZ operation is being performed is confirmed again by ON / OFF of the PTZ operation flag (step S108). This corresponds to the case where the PTZ operation is still in progress. When the operation flag is ON (step S108-YES), the process returns to step S105 in order to perform stillness determination on the subsequent captured image.

On the other hand, if the operation flag is OFF in step S108 (step S108-NO), an intruder detection process is performed on the received captured image (step S109).
This intruder detection process is a process in which the intruder detection unit 206 obtains target_x, y coordinates (intruder's current position coordinates), a zoom target rectangle, and the like as detection results based on the interframe difference obtained for the captured image. (See description of <Intruder Detection> above).
The procedure of the intruder detection process is performed according to the subsequence of FIG. According to the sequence of FIG. 11, first, the inter-frame difference of the captured images that are continuous in time series is taken (step S401).
As a result of taking the interframe difference, there may be a case where no difference occurs at all. Next, it is confirmed whether or not a difference image is obtained (step S402). If a difference image is not obtained (step S402-NO), the subsequent processing of this subsequence is passed. In this way, by passing this sub-sequence without performing subsequent processing, wasteful resource consumption is avoided.

When a difference image is obtained in step S402 (step S402-YES), a labeling process is performed on the obtained difference image (step S403). Labeling is a connected pixel area unit (an area where pixels are connected to form one cluster, in which pixels having the same data value (white or black pixels in the case of a binarized image) are connected, in this embodiment. Each intruder is included in this area), and a label for identifying the area is attached to each area and used as management information.
Next, noise is removed in order to extract only the intruder to be processed from the connected pixel region labeled in step S403 (step S404). For example, a method of removing an isolated small area as noise can be employed.
Thereafter, a processing target rectangle is calculated based on the difference image of the intruder as the processing target obtained in the processing of step S404 (step S405). The processing target rectangle obtained here is a unit of an image recognized as a difference image of the same intruder, and calculates the position (for example, coordinates of the center position) and size (vertical / horizontal length) of the rectangle circumscribing the image. To do.

  If the difference image of the intruder obtained by the inter-frame difference is one block, there is no problem in recognizing it as the same intruder image. However, if a plurality of difference images are obtained, the intruder is correctly identified. It may be difficult to recognize. In this case, for example, by taking a difference over a large number of frames such as three frames, the movement of the intruder can be predicted, and a plurality of chunks can be related based on the predicted movement. That is, from this association, it can be determined whether the image is a difference image of the same intruder or a difference image of another intruder. The rectangle for performing the PTZ operation illustrated in FIG. 6 is calculated from the rectangles surrounding these images. On the other hand, in the case of a difference image of a plurality of intruders, the plurality of intrusions illustrated in FIG. 7 by the rectangles surrounding these images. A rectangle for performing the PTZ operation corresponding to the person is calculated.

After calculating the processing target rectangle in step S405, the moving direction of the intruder is calculated (step S406). The movement direction of the intruder can be obtained by regarding the center point of the processing target rectangle obtained from the difference image as a coordinate value representing the position of the intruder and calculating a variation of the coordinate value of the center point (described above). (See the description with reference to FIG. 4 in <Intruder Detection>).
Next, target_x · target_y necessary for calculating the pan / tilt value, that is, the x and y coordinates of the intruder to be captured at the center of the screen after the pan / tilt operation is obtained. In the present embodiment, target_x · target_y is predicted from the movement of the intruder, so that a predicted value is obtained using the moving direction of the intruder obtained in step S406 (see FIG. 4 for the above “pan / tilt value”). Referred explanation, see).
Since the numerical values necessary for calculating the PTZ value are obtained in steps S405 to 407, the sub-sequence of FIG. 11 is exited.

Returning to the main control flow (FIG. 8), since there may be cases where an intruder is not detected by the intruder detection process performed in step S109, whether or not an intruder has been detected after performing the intruder detection process. Is confirmed (step S110). If no intruder is detected (step S110-NO), it is meaningless to perform the subsequent processing. In this case, the process returns to step S103, and whether or not the intruder is detected again continues. The process from the step of confirming is performed.
On the other hand, when an intruder is detected (step S110-YES), a process for calculating a PTZ value is performed (step S111).
This PTZ value calculation process is a process performed by the PTZ value calculation unit 207. The processing target rectangle, the intruder movement (movement direction), and target_x · target_y obtained in the intruder detection process subsequence (FIG. 11) are calculated. This is a process for calculating a PTZ value for PTZ operation of the camera 101 (refer to <Description of <PTZ Value Calculation> above).

  The procedure of the PTZ value calculation process is performed according to the subsequence of FIG. According to the sequence of FIG. 12, first, the current angle of view (zoom value) of the camera 101 is acquired (step S501). The current angle of view is an amount necessary for calculation of a pan / tilt value and a calculation of an angle of view (zoom value), which are control targets in the subsequent stage. Note that since the PTZ control system (not shown) on the camera 101 side always detects the PTZ state of the camera, the detected value is acquired from the server terminal 103 side and held as the current value.

Next, a pan / tilt value calculation process as a control target is performed (step S502). The pan value is calculated based on “target_x” obtained in the intruder detection process (FIG. 11) and the current horizontal angle of view of the camera 101 obtained in step S501. Is calculated according to the equation (1) shown in FIG. The tilt value is calculated based on target_y and the vertical angle of view in the same manner as the pan value.
Further, a zoom value calculation process as a control target is performed (step S503). The zoom value is calculated based on the processing target rectangle (zoom target rectangle or the like) obtained in the intruder detection process (FIG. 11) and the current angle of view of the camera 101 acquired in step S501. Is calculated according to the equation (2) shown in “Zoom value”.
In this way, the PTZ values are calculated, and the sub-sequence of FIG. 12 is exited.

Returning to the main control flow (FIG. 8), in order to execute the control operation based on the PTZ value calculated in step S111, the obtained value is transmitted to the camera 101 as a PTZ command. Check the PTZ value to see if it can be done.
First, it is confirmed whether or not the PTZ value obtained as the control target value is within the movable range of the camera 101 (step S112). Since the movable range of the camera 101 has acquired the upper limit value of the PTZ value in step S101, it is confirmed whether or not the upper limit value is exceeded.
Here, if the PTZ value obtained as the control target value exceeds the upper limit value of the PTZ value (step S112-NO), normal operation cannot be obtained, so the camera 101 is panned / tilted to a wide angle. Return to the initial state and start a new intruder detection.

On the other hand, when the PTZ value obtained as the control target value does not exceed the upper limit value of the PTZ value (step S112-YES), normal operation is obtained, so another operating condition is confirmed. The operation condition is that the difference between the PTZ value calculated in step S111 and the current value is a predetermined value or more, and the control execution condition is checked to see if this condition is satisfied (step S113).
Here, if the difference between the calculated PTZ value and the current value is not equal to or greater than the predetermined value (step S113-NO), the calculated PTZ value is canceled, that is, the operation of the camera 101 is not performed and intruder detection is performed. Return to step S105. This is performed, for example, in order to prevent the movement speed of the intruder from being slow and not having the effect of operating the camera 101 so that the operation becomes useless or unstable. At this time, the PTZ operation flag is kept OFF so that intruder detection can be performed immediately.

On the other hand, if the difference between the calculated PTZ value and the current value is greater than or equal to a predetermined value (step S113-YES), control based on the calculated PTZ value is executed, so the PTZ command sending unit 208 is connected via the communication interface unit 204. The PTZ value is transmitted to the camera 101 as a PTZ command (step S114).
After transmitting the PTZ command in step S114, the PTZ operation flag is turned ON (step S115), and the process returns to step S105 to detect intruders. The reason why the PTZ operation flag is set to ON is that it is known that the operation according to the PTZ command transmitted from the camera 101 is performed, and thus the camera stillness determination (step S107) is required in the process of performing the intruder detection (step S109). Because.

100 ... Intruder (mobile) monitoring system 101 ... PTZ camera 103 ... Server terminal 105 ... Display terminal 201 ... Control unit 202 ... Image receiving unit 203 ... Image recording unit 204... Communication interface unit 205 205 Camera stillness determination unit 206 Intruder detection unit 207 PTZ value calculation unit 208 PTZ command sending unit 209 Bus

Claims (7)

A PTZ camera that takes a video, a moving body detection unit that processes a captured image of the PTZ camera and detects a moving body that appears on the image plane, and a control that captures the moving body by a PTZ operation of the PTZ camera. A mobile imaging device having a control means for performing based on a detection result,
Camera stationary determination means for determining that the PTZ camera is stationary,
The control means estimates based on the angle of view of the PTZ camera and the position information of the moving object to be captured detected on the image plane by the moving object detection means when the camera stationary determination means determines the stationary state. The PTZ according to the pan / tilt value corresponding to the control target position and the zoom value corresponding to the control target angle of view determined based on the difference image of the moving object to be captured detected on the image plane by the moving object detection means. A moving body imaging apparatus characterized by performing an operation. The moving body imaging device according to claim 1,
The camera stillness determination means is characterized in that a stillness determination condition is that an area of an image obtained by taking an inter-frame difference in an outer peripheral area on an image plane taken by a PTZ camera is smaller than a predetermined value. apparatus. The moving body imaging device according to claim 1,
The control means estimates the control target position for obtaining a pan / tilt value from a time-series change of a center position of a circumscribed rectangle surrounding a moving body image obtained by calculating a difference between frames. Mobile body imaging device. The moving body imaging apparatus according to any one of claims 1 to 3,
The control means is configured so that the longer pixel size of the circumscribed rectangle surrounding the moving body image obtained by taking the inter-frame difference becomes a predetermined value obtained as the pixel size after zooming. A moving body imaging apparatus characterized by determining an angle of view. In the moving body imaging device according to any one of claims 1 to 4,
The control means, on the condition that the moving direction estimated from the time series change of the center position of the circumscribed rectangle surrounding the moving body image obtained by taking the difference between frames has changed beyond a predetermined amount, the control target image. A moving body imaging apparatus characterized in that the angle is set to a value for enlarging the angle. The moving body imaging device according to any one of claims 1 to 5,
The moving body imaging apparatus characterized in that the control means determines the control target angle of view so that a plurality of moving bodies obtained by taking inter-frame differences are within an image plane after zooming. The moving body imaging device according to any one of claims 1 to 6,
As the initialization operation, the control means performs a PTZ operation with a predetermined wide-angle zoom value and a predetermined pan / tilt value, and performs the initialization operation when a moving body is not detected for a predetermined time or more by the moving body detection means. A moving body imaging apparatus characterized by performing:

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