JP4759426B2 - Imaging device - Google Patents

Description

  The present invention relates to a photographing apparatus that photographs a moving subject such as a vehicle traveling on a road, and more particularly to a vehicle detection system that can photograph a vehicle and identify a license plate, a vehicle type, or a driver's face.

As a vehicle detection system, a so-called orbis (automatic speed control machine), an automatic license plate reader, and the like are arranged, and control and monitor a vehicle traveling on a road. As the Orbis, a radar-type Orbis is known. The speed of the vehicle is measured by the Doppler effect, and the vehicle is photographed with a camera installed on the road (see, for example, Patent Document 1 and Patent Document 2). In the case of the “new H system” which is one of the radar systems, intermittent data is used and image data is automatically transferred using a digital camera. On the other hand, the so-called “N system” is known as an automatic license plate reader, which recognizes the license plate of a vehicle traveling in each lane in real time, and determines the vehicle to be tracked by a monitoring device installed in another place. It detects (for example, refer patent document 3).
JP-A-2-302899 JP-A-4-299277 Japanese Patent No. 3402263

  In general, the resolution required for an image obtained by shooting differs depending on the shooting target. The driver's face is required to have a higher resolution than the license plate or vehicle type. However, when the vehicle is traveling at an overspeed (for example, 50 to 60 m / s), it is difficult to photograph a specific vehicle in a state where it is completely in focus by an automatic speed regulator. Necessary information such as plates cannot be obtained. Therefore, it is necessary to improve the resolution using a special camera having a high number of pixels. However, when shooting data is transmitted to the data management unit as it is, such as in the new H system, the data capacity becomes enormous for high-resolution images and the processing speed decreases, and the vehicles that pass sequentially are measured flexibly. I can't. In addition, vehicle monitoring systems such as the Orbis (speed control machine) and the N system are constructed separately, and it is not possible to switch between speed control and license plate recognition as appropriate.

  In the present invention, there are provided an imaging device and a vehicle detection system capable of performing various imaging operations by logically setting imaging conditions in consideration of resolution.

  The photographing device of the present invention is a device that photographs a moving subject such as a vehicle, and is installed along a moving direction of the subject in order to capture the subject, speed detecting means for measuring the speed of the moving subject, Based on the camera having the image sensor, the three-dimensional resolution conversion diagram, the calculation means for calculating the shooting point according to the shooting characteristics of the camera and the required resolution, and so as to shoot the subject when the subject passes through the shooting point, An image capturing control unit that controls the operation of the camera based on the speed of the subject and an image transfer unit that outputs a still image obtained by the image capturing to the outside are provided. As the speed detection means, for example, a radar type or a loop coil type speed detector is applied. The captured image is transmitted as data to a central control unit or the like. The camera is installed along the moving direction of the subject so that the subject moving within the field of view of the camera lens can be captured (so that a subject image can be obtained). The camera is preferably a still camera, or a movie camera may be used. A camera that can convert the number of pixels by thinning processing or the like, or a variable focus camera such as a zoom lens may be used. Furthermore, a camera having only the function of the imaging unit may be prepared, and an image data generation unit may be separately provided. When the subject can move in a plurality of moving areas, a plurality of recording cameras are prepared as many as the moving areas, and a plurality of recording cameras are installed along the moving direction of the subject. Then, it is only necessary to provide a specifying means for specifying a moving area in which a subject to be photographed moves. The moving region specified by the specifying means is moved, and the photographing operation is performed on the subject approaching the camera. In order to specify the moving area of the subject, for example, a subject specifying camera capable of photographing the vicinity of the speed detection point far from the photographing point is provided. Then, the specifying means specifies the moving area of the subject to be shot based on the image taken by the subject specifying camera, and the shooting control means is a camera corresponding to the moving area specified among the plurality of recording cameras. And the shooting operation may be controlled. In order to reduce the number of pixels of the recording camera, the angle of view of the shooting optical system of the camera for identifying the subject is wider than the angle of view of the shooting optical system of the plurality of recording cameras. The camera can be set to a narrow lens camera.

  A three-dimensional resolution conversion diagram provided in the present invention will be described. First, the resolution related to the subject, which is the product of the shooting distance (shooting point) to the subject and the resolution (on the plane) required according to the subject, is defined (in this case, it is a parameter including the distance). 3D resolution) The three-dimensional resolution refers to shooting conditions that affect the resolution of the subject image, that is, the angle of view of the shooting optical system that differs depending on the wide and narrow cameras, and the number of pixels that make up the subject image that is recorded during shooting (hereinafter referred to as shooting pixels). The number of pixels of the image sensor and the angle of view of the photographic optical system are referred to as camera characteristics). The angle of view of the photographic optical system is preferably expressed in radians (rad) considering that the distance from the photographic optical system to the subject is constant regardless of the left-right variation of the subject position. In this case, an f-θ lens is used. However, the angle of view may be represented by a horizontal angle of view (°) in order to adapt to a generally used camera. The on-plane resolution is represented by, for example, dpi (dot per inch).

  The required on-plane (subject image) resolution varies depending on the subject to be imaged. Accordingly, in the present invention, based on the defined three-dimensional resolution, the correspondence between the combination of the field angle of the photographing optical system and the number of photographing pixels constituting the subject image and the three-dimensional resolution, that is, the product of the resolution and the distance to the subject. A three-dimensional resolution conversion diagram representing the relationship is prepared. In the three-dimensional resolution conversion diagram, combinations of the field angle of the photographing optical system and the number of photographing pixels are plotted. There are innumerable combinations of the angle of view of the photographing optical system and the number of photographing pixels that satisfy the required resolution, but this combination is illustrated by the three-dimensional resolution. The three-dimensional resolution conversion diagram is illustrated taking into consideration that the human visual sensation tends to be logarithmic, and in particular, the logarithm with the angle of view of the photographing optical system and the number of pixels to be photographed as two bases. When the three-dimensional resolution value is expressed by an exponential function with 2 as the base, the locus of the plot of the combination is expressed as a line having a predetermined value and three-dimensional resolution linearity. . A plurality of three-dimensional resolution linear lines are defined according to the resolution value, and a combination of the angle of view of the photographing optical system and the number of photographing pixels corresponds one-to-one along each line. Based on such a three-dimensional resolution conversion diagram, the angle of view of the photographing optical system, the number of photographing pixels, the distance to the subject, and the resolution on the plane can be set.

  For example, the shooting distance (shooting point) is set from the three-dimensional resolution conversion diagram so as to satisfy the required on-plane resolution under the condition that the angle of view and the number of pixels of the shooting optical system are constant. Alternatively, the angle of view of the photographic optical system may be set from the three-dimensional resolution conversion diagram so that the required on-plane resolution is satisfied under the condition that the number of photographic pixels and the photographic distance (photographing point) are constant. Furthermore, the combination of the angle of view of the photographic optical system and the number of photographic pixels can be set from the three-dimensional resolution conversion diagram so that the required on-plane resolution is satisfied under the condition that the photographic distance (photographing point) is constant. Good.

  By defining such a three-dimensional resolution and defining a three-dimensional resolution conversion diagram, an appropriate photographing condition is uniquely determined. A subject image having a necessary resolution is photographed and recorded by performing a photographing operation based on the obtained photographing conditions in accordance with the data of the three-dimensional resolution conversion diagram. That is, as with a program diagram used to calculate the aperture value of the camera and the exposure value of the shutter speed, the shooting conditions are determined logically and uniquely rather than fuzzy (heuristic).

  In the present invention, the subject distance (photographing spot) is calculated from the required resolution based on the three-dimensional resolution conversion diagram. For example, in the case of a camera in which the number of shooting pixels and the angle of view of the shooting optical system are determined, the shooting distance (shooting point) is uniquely determined from the three-dimensional resolution line and the on-plane resolution. In addition, when the photographing optical system of the camera is a variable focus, that is, a zoom camera and the angle of view can be adjusted, the calculating means calculates the shooting point based on the set resolution and the number of pixels of the image sensor. That's fine. In this way, it is not always necessary to take a high-resolution image, and an image with a required resolution can be obtained even with a camera having an image sensor with several hundred thousand pixels. Further, by using the three-dimensional resolution conversion diagram, even if the required resolution is changed, the shooting point is calculated according to the change, and the shooting conditions can be set flexibly. Also, when the angle of view and the number of photographic pixels of the photographic optical system can be adjusted in the camera, the angle of view is changed or the number of pixels is changed using a three-dimensional resolution conversion diagram when there is a limitation of the photographic range. be able to.

  Further, the functions of the conventional Orbis and N systems can be realized by the same photographing system by the calculation using the data of the three-dimensional resolution conversion diagram. For example, photographing may be performed so as to identify an overspeed vehicle, or continuous photographing may be performed using a camera so that only the license plate is recognized.

  The shooting control device of the present invention is a device that is installed along the moving direction of a subject to capture a moving subject and controls the shooting operation of a camera having an image sensor, based on a three-dimensional resolution conversion diagram, Calculation means for calculating the shooting point according to the shooting characteristics of the camera and the required resolution, and shooting control for controlling the operation of the camera based on the speed of the detected subject so that the subject is shot when the subject passes through the shooting point Means.

  The shooting control method of the present invention is a method for controlling the shooting operation of a camera that is installed along a moving direction of a subject to capture a moving subject and has an image sensor, and based on a three-dimensional resolution conversion diagram, The camera is calculated based on the shooting characteristics of the camera and the required resolution, and the camera is controlled based on the detected speed of the subject so that the subject is shot when the subject passes through the shooting point. .

  The recording medium of the present invention is a recording medium that is installed along the moving direction of a subject to capture a moving subject and stores a program for controlling the photographing operation of a camera having an image sensor. Based on the shooting characteristics of the camera and the required resolution, and the camera operates based on the detected speed of the subject so that the subject is shot when the subject passes through the shooting point. A program for functioning the imaging control means for controlling is stored.

  The program of the present invention is a program that is installed along the moving direction of a subject to capture a moving subject and controls the shooting operation of a camera having an image sensor, and based on a three-dimensional resolution conversion diagram, Calculation means for calculating a shooting point according to shooting characteristics and required resolution, and shooting control means for controlling the operation of the camera based on the detected speed of the subject so that the subject is shot when the subject passes through the shooting point; Is made to function.

  The vehicle detection system of the present invention is based on speed detection means for measuring the speed of the vehicle, a plurality of cameras installed along the vehicle movement direction for capturing the vehicle, each having an image sensor, and a three-dimensional resolution conversion diagram. A calculating means for calculating a shooting point according to the shooting characteristics and required resolution of each of the plurality of cameras, a specifying means for specifying a traveling region of the vehicle to be shot, and a vehicle when the vehicle passes through the shooting point. It is characterized by comprising a photographing control means for controlling the operation of a camera corresponding to a specified traveling region based on speed so as to photograph, and an image transferring means for outputting a still image obtained by photographing to the outside. To do.

  The vehicle detection method of the present invention measures the speed of a vehicle and, based on a three-dimensional resolution conversion diagram, capture characteristics of each of a plurality of cameras installed along the vehicle movement direction to capture the vehicle and each having an image sensor. In accordance with the required resolution, the shooting point is calculated, the travel region of the vehicle to be imaged is specified, and the camera corresponding to the specified travel region is photographed so that the vehicle is photographed when the vehicle passes through the shooting point. The operation is controlled based on the speed, and a still image obtained by photographing is output to the outside.

  According to the present invention, a moving subject such as a vehicle can be appropriately photographed with a simple configuration using a general-purpose camera.

  Below, with reference to drawings, the vehicle monitoring system which is embodiment of this invention is demonstrated.

  FIG. 1 is a diagram schematically illustrating the entire vehicle detection system according to the present embodiment. FIG. 2 is a diagram schematically illustrating the vehicle photographing device.

  The vehicle detection system is installed on a road R having a plurality of lanes such as an expressway, and includes a vehicle photographing device 10, a photographing control device 20, and a speed detector 30. The imaging control device 20 is connected to a traffic monitoring center 40 located away from the road R. The speed detector 30 is a loop coil type speed detecting device, and detects the vehicle speed based on a magnetic field change when passing through a coil (not shown) embedded in the road R in advance.

  As shown in FIG. 2, the vehicle photographing apparatus 10 includes one wide-area camera (wide-angle lens camera) M1 and three narrow-area cameras (telephoto lens cameras) C1, C2, and C3. Each camera is a photographing control apparatus. 20 is remotely controlled. The wide area camera M1 can shoot with a wide field angle (30 degrees to 60 degrees) that covers all three lanes R1 to R3, and has an image sensor of several million pixels. In the wide area camera M1, the direction of the lens is fixed in advance so as to capture a vehicle at a distance of 50 to 100 m from the camera position.

  On the other hand, each of the narrow-area cameras C1, C2, and C3 has a variable focus telephoto lens that can perform shooting at an angle of view (5 degrees to 20 degrees) according to the lanes R1, R2, and R3 and the vehicle size. Each camera is provided with an image sensor having a number of about 500,000 pixels. The wide-area camera M1 performs imaging in real time (time interval of several tens of mmsec), while the narrow-area cameras C1, C2, and C3 perform imaging operations on specific vehicles that are overspeeded. The narrow-area cameras C1, C2, and C3 are equipped with lens orientation adjusting mechanisms B1, B2, and B3 that finely adjust the lens orientation of the cameras, respectively, and vehicles that pass at a point 20 to 40 m away from the camera installation position. The lens orientation is adjusted so as to shoot.

  When an overspeed vehicle approaches and the speed detector 30 detects the vehicle speed, a signal informing the overspeed detection is transmitted to the imaging control device 20. Then, when the vehicle that has passed through the measurement point of the speed detector 30 and is closest to the measurement point and the lane in which the vehicle travels are identified from the shooting information of the wide area camera M1, the shooting control device 20 Control of the photographing operation by remote control is executed for the camera corresponding to the lane. The narrow-area cameras C1, C2, and C3 generate image data by shooting, and the image data is transmitted to the traffic monitoring center 40 via the shooting control device 20.

  FIG. 3 is a block diagram of the imaging control device 20.

  The imaging control device 20 includes a controller 22, a calculation unit 24, an image memory 26, a memory 28, and a lane specifying unit 29, and a controller 22 having a ROM (not shown) that stores a program for controlling the entire imaging operation. The operation of the imaging control device 20 is controlled. In the lane specifying unit 29, the lane in which the vehicle travels is specified by automatic recognition processing based on the moving images sequentially sent from the wide area camera M1.

  The memory 28 stores table data corresponding to a later-described three-dimensional resolution conversion diagram, and the calculation unit 24 calculates a shooting point (subject distance) of the vehicle based on the table data. The controller 22 calculates the shutter timing based on the travel lane information sent from the lane specifying unit 29 and the shooting point calculated by the calculation unit 24 and the speed data transmitted from the speed detector 30. A photographing operation execution signal is transmitted at a predetermined timing to the narrow-area camera to be operated. The selected narrow area camera captures the vehicle with a predetermined aperture value and shutter speed. The still image obtained by photographing is transferred to the image memory 26 and further transmitted to the traffic monitoring center 40. When the shooting location is changed, a control signal is transmitted to the lens orientation adjusting mechanism in order to correct the lens orientation. As will be described later, when changing the resolution or the like of a captured image, a control signal is transmitted from the traffic monitoring center 40 to the controller 22, and the controller 22 controls the arithmetic unit 24 based on the received control signal. In the calculation unit 24, shooting conditions are set based on the changed resolution and the like.

  FIG. 4 is a three-dimensional resolution conversion diagram. FIG. 5 is a diagram showing the resolution required for the subject. 6 and 7 are diagrams illustrating the relationship between the three-dimensional resolution and the distance to the subject. FIG. 7 is a diagram showing the relationship between the distance to the subject and the three-dimensional resolution conversion diagram. A three-resolution conversion diagram that can be used as a program diagram will be described with reference to FIGS. In the following, the resolution of the subject image obtained by photographing is represented by dpi (dot per inch≈25.4 dots / mm).

  The three-dimensional resolution conversion diagram shown in FIG. 4 represents a graph in which the vertical axis represents the number of pixels to be photographed and the horizontal axis represents the angle of view of the photographing optical system, and the values represented by logarithms each having a base of 2 are plotted. . The angle of view of the photographing optical system is represented by a horizontal angle of view. When the horizontal angle of view of 60 degrees is used as a reference, the reference angle of view is approximately twice, four times, 1/2 times, 1/4 times, / 8 times the angle of view can be set. Here, a logarithmic value when the reference angle of view is changed by 2 times and 1/2 times is defined as an angle of view value Av (here, 1 to 6).

  On the other hand, the number of photographic pixels is set as a reference pixel number of 500,000 pixels, and the number of pixels is set to be twice, four times, eight times, and sixteen times the reference number of photographic pixels. Here, the logarithmic value when the reference number of photographic pixels is changed by a factor of two is defined as the photographic pixel value Pv (here, 1 to 5). The shooting pixel value Pv and the view angle value Av are both expressed as integers, and each time the shooting pixel value Pv changes to 0, 1, 2, 3,. Every time it changes to 0, 1, 2, 3,..., The angle of view changes twice. The reason for setting such a logarithmic value is that the visual sense tends to be logarithmic.

  As shown in FIG. 5, the resolution on a plane required for a subject image obtained by photographing varies depending on the subject. For example, when discriminating the shape and type of a car, the resolution is required to be 2 dpi, and it is not necessary to photograph the car with a higher resolution. On the other hand, in the case of a license plate, a resolution of 4 dpi is required to identify numbers. Furthermore, a human face recognition requires a resolution of 8 dpi, and a character recognition requires a resolution of 16 dpi.

Here, the three-dimensional resolution α (dpi · m) is defined by the following equation based on the distance to the subject and the on-plane resolution. However, γ represents the distance (m) to the subject, and β represents the resolution (dpi) set according to the subject.

α = β × γ (1)

The value of the three-dimensional resolution α varies depending on the resolution β required for the subject to be imaged when the distance γ to the subject is predetermined. In addition, when the resolution β is determined by determining the shooting target in advance, the value of the three-dimensional resolution α changes according to the distance γ to the subject.

  The resolution of the subject image obtained by photographing depends on the number of pixels constituting the subject image at the time of photographing, the angle of view of the photographing optical system, and the distance γ to the subject. The greater the number of shooting pixels, the higher the resolution, and the narrower the angle of view, the higher the resolution. Also, the shorter the distance γ to the subject, the better the resolution.

  In the three-dimensional resolution conversion diagram shown in FIG. 4, the value of the three-dimensional resolution α on the line obtained by extending the plot in the oblique direction is constant, and the combination of the number of pixels to be captured and the angle of view and the three-dimensional resolution α (distance γ And the product of resolution β) have a one-to-one correspondence. This is because when the subject is present along an arc drawn according to the horizontal angle of view, the distance γ to the subject is constant when the horizontal angle of view is expressed in radians, and the distance γ is arbitrary relative to the horizontal angle of view. This is because the line group with the three-dimensional resolution α can be displayed when the certain degree is satisfied. Here, a line with a three-dimensional resolution (20, 40, 80, 160, 320) that sets the three-dimensional resolution α = 10 as a reference value and is twice, four times, eight, sixteen, or thirty-two times the reference value. A group is formed. By defining a graph in which logarithmic values are plotted in this way, combinations of the angle of view and the number of photographic pixels that satisfy the same three-dimensional resolution α are displayed in a linear relationship. By determining the combination of the angle of view and the number of photographic pixels according to the line of the three-dimensional resolution α, a subject image having the required resolution β can be obtained.

  For example, when the distance γ to the subject is 10 m, the number of shooting pixels is 500,000 pixels (pixel value Pv = 1), and the horizontal field angle is 60 degrees (field angle value Av = 4), the three-dimensional resolution α = 20. At this time, a subject image having a resolution of 2 dpi can be obtained from equation (1). By tracing a line with a three-dimensional resolution α = 20, a subject image having a resolution of 2 dpi can be obtained by various combinations of the number of captured pixels and the angle of view.

  In addition, when the required resolution is changed in a state where the distance γ to the subject is determined, it is possible to set an appropriate angle of view and the number of shooting pixels using the three-dimensional resolution conversion diagram of FIG. is there. For example, when the distance γ to the subject is 10 m and the resolution β required for the subject image is 4 dpi, the shooting condition depends on the combination of the number of pixels and the angle of view on the line of the three-dimensional resolution α = 40 in FIG. Is determined. Furthermore, as shown in FIGS. 6 and 7, when the three-dimensional resolution α is determined, the resolution β changes according to the distance γ.

  Since the camera does not apply the f-θ lens, and the subject width is very small compared to the distance γ to the subject, it is often possible to set shooting conditions. Therefore, the horizontal image corresponding to each radian value can be set. A three-dimensional resolution conversion chart can be defined using the corners. The reference horizontal field angle of 60 degrees is substantially equal to 1 rad.

  In the present embodiment, the shooting point, that is, the shooting distance γ is determined by the three-dimensional resolution conversion diagram in accordance with the required resolution β such as the characteristics of the vehicle, that is, the license plate and the driver's face. When the resolution β is changed, the shooting distance γ or the horizontal angle of view and the number of shooting pixels corresponding to the new resolution β are determined based on the three-dimensional resolution conversion diagram.

  FIG. 8 is a flowchart showing a shooting control process executed in the shooting control device 20. FIG. 9 is a diagram showing the relationship between the vehicle and the camera position. FIG. 10 shows a captured still image.

  In step S101, data related to the resolution sent from the traffic monitoring center 40 is received. The data related to the resolution is appropriately changed according to the purpose of use of the vehicle monitoring system, for example, speed control or traffic monitoring. When the vehicle monitoring system functions as a speed regulator, it is necessary to specify the vehicle type, license plate, and driver's face of the overspeed vehicle, so that a resolution of 8 dpi is required. On the other hand, when the vehicle monitoring system is to function as a traffic monitoring device in a traffic jam, a resolution of 4 dpi may be used to reduce the amount of image data. Here, a case where a resolution of 8 dpi is requested will be described. In step S102, the photographing point P, that is, the distance γ from the camera to the vehicle is calculated based on the equation (1) and the three-dimensional resolution conversion diagram shown in FIG. The distance γ to the vehicle is calculated based on the number of pixels of the narrow-area cameras C1, C2, and C3 (about 500,000 pixels) and the horizontal angle of view of the camera. Here, since the horizontal angle of view A is initially set to 7.5 degrees and the number of pixels is 500,000, the three-dimensional resolution (resolution constant) α is set to 160 from the three-dimensional resolution conversion diagram of FIG. It is done. Accordingly, the distance γ to the shooting point P is determined to be “20 m” from the equation (1). A control signal for operating the lens direction fine adjustment mechanism is output according to the calculated shooting distance γ.

  In step S103, it is determined whether an overspeed vehicle B is detected. In the present embodiment, speed data is transmitted from the speed detector 30 to the imaging control device 20 when a vehicle having a speed of 40 m / s or more passes. In step S104, the lane in which the overspeed vehicle is traveling is identified based on the captured image sent from the wide area camera M1. Then, the shutter timing is calculated based on the vehicle speed.

As shown in FIG. 9, the position P2 at which the speed detector 30 detects the vehicle speed is determined in advance, and the distance from the camera installation position to the speed detection position P2 is represented as L. Based on the distance γ to the shooting point P, the distance L2 to the speed detection position P2, and the detected vehicle speed v, the time Δt required for the vehicle B to move from the speed detection position P2 to the shooting point P1 is: It is calculated by the formula.

Δt = (L−γ) / v (2)

Accordingly, the shutter timing is set so that photographing is executed Δt seconds after the vehicle B having an overspeed is detected. The overspeed vehicle B travels at a speed of 40 to 50 m / s, and the distance from P1 to P2 is very short with respect to the vehicle speed. Therefore, between the speed detection position P2 and the shooting point P1, There is no problem assuming that the vehicle B passes at substantially constant speed.

  In step S105, a control signal is output to a predetermined camera so that the photographing operation is executed by a specific camera after Δt seconds after the vehicle B passes the speed detection position P2. As a result, a still image in which the vehicle B is captured is obtained as shown in FIG. Here, since the resolution β is set to 4 dpi, a still image having a resolution capable of recognizing the license plate can be obtained. In step S <b> 106, the captured image data is transmitted to the image memory 26 and then transmitted to the traffic monitoring center 40.

  In step S107, it is determined whether or not command data for changing the resolution is sent from the traffic monitoring center 40. If it is determined that the resolution change command data has not been sent, the process returns to step S103. On the other hand, if it is determined that the command data for changing the resolution has been sent, the process returns to step S102.

For example, when the angle of view is set to 15 degrees, the resolution β is set to 4 dpi, and as a result, the resolution β is changed to 8 dpi from the state where the shooting distance γ is set to 20 m, the shooting distance γ is calculated from the equation (1). It is set to 10m. However, since the shooting distance γ can only be set in the range of 20 m to 40 m, the horizontal angle of view of the camera is changed from 15 degrees to 7.5 degrees. That is, the focal length of the photographic lens (not shown) is changed to the telephoto side.

  When the horizontal field angle is set to 7.5 degrees in advance, the resolution constant α is 160 from the three-dimensional resolution conversion diagram, the shooting distance γ is 40 m when the resolution β is 4 dpi, and the shooting distance is 20 m when the resolution is 8 dpi. It is done.

  As described above, according to the present embodiment, when the vehicle speed is detected by the speed detector 30, the shooting control device 20 calculates the shutter timing based on the preset resolution and shooting distance. Further, the travel lane of the vehicle is specified by the captured image of the wide area camera. Then, the corresponding narrow-area camera is controlled so as to take an image when the vehicle passes through a predetermined imaging point, and a still image of the vehicle is transmitted to the traffic monitoring center 40.

  In addition, in order to specify all the vehicles which drive a lane like N system, a movie camera may be used and a license plate may be recognized by continuous imaging | photography (for example, 10-40 mmsec space | interval). In this case, when the horizontal field angle is set to 15 degrees and the resolution is set to 4 dpi for license plate recognition, the resolution constant α is set to 80 according to the three-dimensional resolution conversion diagram, and the shooting distance γ is set to 20 m according to the equation (1). Determined. Then, the speed of each vehicle is detected, and the time Δt required to move from the speed detection position P2 to the photographing point P1 is calculated according to the speed, and the photographing operation is executed after the time Δt has elapsed.

Also, when using a multi-million pixel camera to identify all overspeed vehicle models, license plates, and driver's faces , all pixels are used. You may perform photography by. For example, when a camera with 2 million pixels is used, when the horizontal field angle is set to 15 degrees, the resolution constant α is set to 160, and when the resolution β is 8 dpi, the shooting distance γ is 20 m. On the other hand, the constant because the resolution β in 4Dpi, if you set the number of pixels to 500,000 pixels, resolution constant α is defined in 80, Range γ becomes 20 m (see FIG. 4).

  The three-dimensional resolution α, the number of imaging pixels, the angle of view of the imaging optical system, the on-plane resolution β, and the distance γ to the subject are not limited to the values shown in FIG. May be. When the angle of view of the photographic optical system is expressed in radians, it is only necessary to shoot by applying an f-θ lens.

  In the three-dimensional resolution conversion diagram, the number of captured pixels and the angle of view may be represented by a logarithm having a base other than 2 and a logarithm having a base of 2, and a three-dimensional resolution conversion diagram may be created. The angle of view of the photographing optical system may be set with a configuration other than the zoom lens. For example, a photographing optical system having a plurality of focal lengths may be prepared and selectively installed. Further, image data may be generated in the imaging control device.

  A radar-type speed detector may be applied, and the lane may be specified without using a wide area camera. Moreover, you may comprise so that a vehicle may be detected on the road of one lane. Regarding the lane identification of the traveling vehicle, a laser may be irradiated along a direction perpendicular to the lane, and the lane in which the vehicle is traveling may be identified by laser scanning. Alternatively, the entire one lane of the expressway may be photographed with a wide area camera, and each lane may be photographed with a narrow area camera.

1 is a diagram schematically illustrating an entire vehicle detection system according to an embodiment. It is the figure which showed the vehicle imaging device schematically. It is a block diagram of an imaging | photography control apparatus. It is a three-dimensional resolution conversion figure. It is the figure which showed the resolution requested | required of a to-be-photographed object. It is the figure which showed the relationship between 3D resolution and the distance to a to-be-photographed object. It is the figure which showed the relationship between a three-dimensional resolution conversion figure and the distance to a to-be-photographed object. It is the flowchart which showed the imaging | photography control processing performed in an imaging | photography control apparatus. It is the figure which showed the relationship between a vehicle and a camera position. It is the figure which showed the image | photographed still image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle imaging device 20 Imaging control device 22 Controller 24 Calculation unit 30 Speed detector 40 Traffic monitoring center M1 Wide area camera C1, C2, C3 Narrow area camera α Three-dimensional resolution (resolution constant)
β Resolution on the plane (resolution)
γ Shooting distance (shooting point)

Claims (17)

Speed detecting means for measuring the speed of the subject moving in the subject moving area ;
And it has an imaging optical system and the imaging device, installed in accordance with the subject moving region to capture the object to be mobile camera,
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the imaging optical system, the angle of view and the number of the image pickup pixels and the subject of the imaging optical system according to the plane on resolution required depending, a calculating means for calculating a photographing point,
Shooting control means for shooting the subject by calculating a shutter timing when the subject passes through the shooting point based on the detected speed and controlling the operation of the camera based on the shutter timing ;
Image transfer means for outputting an image obtained by shooting to the outside ,
The moving subject photographing apparatus , wherein the three-dimensional resolution is a product of a distance to a subject and the on-plane resolution . The calculation means calculates a shooting point for an overspeed subject moving at a speed equal to or higher than a predetermined speed,
The moving subject photographing apparatus according to claim 1, wherein the photographing control unit performs photographing on the overspeed subject. The speed detecting means detects a speed for each of a plurality of moving subjects that sequentially move in the subject moving region;
It said imaging control means, calculates the shutter timing of each mobile object based on the speed detected by the operation control of the camera based on the shutter timing, characterized by sequentially capturing the plurality of moving object The moving subject photographing apparatus according to claim 1. 2. The moving subject photographing apparatus according to claim 1, further comprising means for detecting whether or not the on-plane resolution has been changed . The moving object photographing apparatus according to claim 1, wherein the computing unit changes a photographing point based on the three-dimensional resolution conversion diagram in accordance with the change of the on-plane resolution. The focal length of the photographing optical system is variable,
The calculation means can change the angle of view of the photographing optical system from the three-dimensional resolution conversion diagram under the condition that the photographing point and the number of photographing pixels are constant according to the change of the on-plane resolution,
2. The moving subject photographing apparatus according to claim 1 , wherein the focal length is changed as the angle of view of the photographing optical system is changed . The camera is a camera capable of changing the number of pixels used by the imaging device;
The arithmetic means can change the number of pixels to be photographed from the three-dimensional resolution conversion diagram under the condition that the photographing point and the angle of view of the photographing optical system are constant according to the change in the on-plane resolution,
The moving subject photographing apparatus according to claim 1 , wherein the number of pixels used by the image sensor is changed as the number of photographing pixels is changed . As the camera, a plurality of recording cameras are installed according to a plurality of subject movement areas, respectively.
The moving subject photographing apparatus according to claim 1, further comprising a specifying unit that specifies a moving region in which a subject to be photographed moves. A subject identifying camera capable of photographing the vicinity of the speed detection point on the far side from the photographing point is further provided as the camera.
The specifying means specifies a moving area of a subject to be photographed based on a photographed image by the subject identifying camera;
9. The moving subject photographing apparatus according to claim 8, wherein the photographing control unit selects a camera corresponding to a moving area specified from the plurality of recording cameras and controls a photographing operation.   10. The moving subject photographing apparatus according to claim 9, wherein a field angle of a photographing optical system of the subject specifying camera is wider than a field angle of photographing optical systems of the plurality of recording cameras. 2. The moving subject photographing apparatus according to claim 1, wherein the computing unit calculates the photographing point based on a set on- plane resolution and the number of pixels of the image sensor. An apparatus that has a photographing optical system and an image sensor, and controls a photographing operation of a camera installed in accordance with the subject moving area so as to capture a subject moving in the subject moving area ,
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the imaging optical system, the angle of view and the number of the image pickup pixels and the subject of the imaging optical system according to the plane on resolution required depending, a calculating means for calculating a photographing point,
Photographing control means for photographing the subject by calculating a shutter timing when the subject passes through the photographing point based on the detected speed of the subject and controlling the operation of the camera based on the shutter timing ; equipped with a,
The photographing control apparatus , wherein the three-dimensional resolution is a product of a distance to a subject and the on-plane resolution . A method for controlling a photographing operation of a camera that has a photographing optical system and an image sensor and that is installed in accordance with the subject moving area so as to capture a subject moving in the subject moving area ,
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the imaging optical system, the angle of view and the number of the image pickup pixels and the subject of the imaging optical system according to the plane on resolution required depending calculates a photographing point,
A method for photographing the subject by calculating a shutter timing when the subject passes through the photographing point based on a detected speed of the subject, and controlling the operation of the camera based on the shutter timing. ,
An imaging control method , wherein the three-dimensional resolution is a product of a distance to a subject and the on-plane resolution . A recording medium having a photographing optical system and an image sensor, and storing a program for controlling a photographing operation of a camera installed according to the subject moving area so as to capture a subject moving in the subject moving area ,
Shooting control device
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the imaging optical system, the angle of view and the number of the image pickup pixels and the subject of the imaging optical system according to the plane on resolution required depending, a calculating means for calculating a photographing point,
Photographing control means for photographing the subject by calculating a shutter timing when the subject passes through the photographing point based on the detected speed of the subject and controlling the operation of the camera based on the shutter timing ; A storage medium storing a program to function
The recording medium , wherein the three-dimensional resolution is a product of a distance to a subject and the on-plane resolution . A program that has a photographing optical system and an image sensor, and controls a photographing operation of a camera installed in accordance with the subject moving area so as to capture a subject moving in the subject moving area ,
Shooting control device
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the imaging optical system, the angle of view and the number of the image pickup pixels and the subject of the imaging optical system according to the plane on resolution required depending, a calculating means for calculating a photographing point,
Photographing control means for photographing the subject by calculating a shutter timing when the subject passes through the photographing point based on the detected speed of the subject and controlling the operation of the camera based on the shutter timing ; A program that allows
The program according to claim 3, wherein the three-dimensional resolution is a product of a distance to a subject and the on-plane resolution . Speed detecting means for measuring the speed of the vehicle;
A plurality of cameras each having a photographing optical system and an image sensor, and installed according to a plurality of traveling areas so as to capture the vehicle,
Hazuki group in the three-dimensional resolution conversion diagram showing a correspondence relationship between imaging pixel number and the three-dimensional resolution constituting the angle of view and the subject image of the photographing optical system, for the plurality of cameras each angle of view of the imaging optical system and according to the plane on resolution required in response to the imaging pixel number and the object, and calculating means for calculating a photographing point,
A specifying means for specifying the traveling region of the vehicle to be imaged;
Calculates the shutter timing of when the vehicle the shooting point based on the detected velocity passes, by operation control of the camera corresponding to the running region specified based on the shutter timing, taking the vehicle and imaging control means that,
A vehicle detection system comprising: image transfer means for outputting a still image obtained by photographing to the outside. Measure the speed of the vehicle,
For each of a plurality of cameras each having an imaging optical system and an imaging device and installed in accordance with a plurality of travel areas so as to capture the vehicle, the angle of view of the imaging optical system and the number of imaging pixels constituting the subject image; Hazuki group in the three-dimensional resolution conversion diagram showing the correspondence between the three-dimensional resolution in accordance with a plane on the resolution to be the imaging request in accordance with the angle of view and the number of the image pickup pixels and the object optical system, calculates a photographing point,
Identify the travel area of the vehicle to be photographed,
Calculates the shutter timing of when the vehicle the shooting point based on the detected velocity passes, by operation control of the camera corresponding to the running region specified based on the shutter timing, taking the vehicle And
A vehicle detection method comprising outputting a still image obtained by photographing to the outside.

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