JP5330289B2 - Imaging apparatus and toll collection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which can pick up the image of a person such as a driver in a vehicle as a high quality of moving image, by reducing the influence of the light reflected on a windshield due to sunlight or the like, even with respect to a vehicle whose windshield angle is different. <P>SOLUTION: The imaging apparatus includes a plurality of cameras, whose installation positions and the polarization angles of polarizing filters that are mounted on their image-pickup face sides are optimized, in order to minimize the light reflected on a windshield with any angle at any vehicle position in an image-pickup area, and configured to measure the windshield angle of the vehicle and the vehicle position, select the optimal camera with respect to the windshield angle of the vehicle and the vehicle position from among the plurality of cameras based on the measured windshield angle and vehicle position, and obtain a moving image from the selected camera. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention provides an ETC (ETC: registered trademark) system (non-stop automatic toll collection) that automatically performs toll collection processing for vehicles using the toll road at a toll gate such as an expressway. In a toll collection system referred to as a system), an imaging device that captures a face image of a person such as a driver traveling in a toll collection lane as a moving image through a windshield, and toll collection using the imaging device About the system.

  For example, in an ETC system, as a method of imaging a person such as a driver in a traveling vehicle through a windshield, the front of the vehicle traveling with strong light such as strobe light is irradiated to image the driver in the vehicle. At the same time, it is known that the number plate located on the lower side of the screen is simultaneously imaged (see, for example, Patent Documents 1 and 2).

  In addition, a method of switching and switching between illumination light having a light distribution characteristic for imaging the entire vehicle and illumination light having a light distribution characteristic for imaging the periphery of the windshield of the vehicle, and reducing image saturation due to reflected light from the windshield Is disclosed (for example, see Patent Document 3).

  Furthermore, as a method for acquiring an image with a weak glass reflection component, a method using an image sensor that can install four-direction polarizing filters at different angles for each pixel and simultaneously capture four-direction polarized images is known. It is known that the component of the reflected light from the windshield is weakened by adjusting the direction of polarization (see, for example, Patent Document 4).

JP 57-67916 A JP 11-316405 A JP 2002-152560 A JP 2007-86720 A

  However, as disclosed in Patent Documents 1 and 2, when a driver in a vehicle is imaged through the windshield by irradiating strong light such as strobe light, the image captured by the camera by reflection on the windshield is saturated. May have. Moreover, in imaging at the time when sunlight exists, it is necessary to irradiate light stronger than sunlight.

  Further, as disclosed in Patent Document 3, in a method of imaging a driver in a vehicle through a windshield using a plurality of light distribution characteristics, there is a problem that a plurality of illuminating means are required and the cost and scale are increased.

  Furthermore, as in Patent Document 4, in the method of imaging using a polarizing filter, the effect of reducing the reflection of sunlight, clouds, and the like varies depending on the mounting angle of the windshield of the vehicle. A method for setting the polarization angle (rotation angle) of the polarizing filter has not been established.

  Therefore, the present invention reduces the influence of the reflected light of the windshield due to sunlight or the like even on vehicles with different windshield angles, and can capture a person such as a driver in the vehicle as a high-quality moving image. An object is to provide a device and a toll collection system.

  The imaging apparatus according to the present invention includes a windshield angle measuring unit that measures an angle of a windshield of a vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road, Vehicle position measuring means for measuring the position of a vehicle traveling in a road imaging area and an image including at least a windshield part of a vehicle traveling in the road imaging area as a moving image, In order to minimize the reflected light from the windshield at an arbitrary angle at an arbitrary vehicle position, a plurality of cameras in which the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side is optimized, and the windshield angle Based on the windshield angle measured by the measuring means and the vehicle position measured by the vehicle position measuring means, the plurality of cameras Select the best camera against the windshield angle and the vehicle position of the vehicle from among, and a camera selection means for acquiring video from the selected camera.

  In addition, the imaging apparatus of the present invention includes a windshield angle measuring unit that measures an angle of a windshield of a vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road. , Which captures an image including at least the windshield portion of a vehicle traveling in the imaging area of the road as a moving image, and minimizes reflected light from the windshield at an arbitrary angle at an arbitrary vehicle position in the imaging area In order to suppress, based on the plurality of cameras that optimize the installation position and the polarization angle of the polarizing filter mounted on the imaging surface side, and the windshield angle measured by the windshield angle measuring means, from among the plurality of cameras Camera selection means for selecting an optimum camera for the windshield angle of the vehicle and acquiring a video from the selected camera; It is provided.

  In addition, the toll collection system of the present invention is a toll road toll for the toll for the vehicle by performing wireless communication with an onboard device mounted on the vehicle entering the toll road at the toll gate. In a toll collection system that performs a toll collection process and captures an image of a person in a vehicle traveling on the road as a moving image through a windshield, the vehicle traveling on the road enters an imaging area set on the road Windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road, vehicle position measuring means for measuring the position of the vehicle traveling within the imaging area of the road, and the imaging area of the road An image including at least a windshield portion of a vehicle traveling inside is captured as a moving image, and can be placed at any vehicle position within the imaging area. In order to minimize the reflected light from the windshield at an arbitrary angle, a plurality of cameras in which the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side is optimized, and the windshield angle measuring means are used. Based on the measured windshield angle and the vehicle position measured by the vehicle position measuring means, an optimum camera for the vehicle windshield angle and the vehicle position is selected from the plurality of cameras, and a moving image is selected from the selected camera. Camera selection means for acquiring the image, and image processing means for processing the moving image acquired by the camera selection means.

  In addition, the toll collection system of the present invention is a toll road toll for the toll for the vehicle by performing wireless communication with an onboard device mounted on the vehicle entering the toll road at the toll gate. In a toll collection system that performs a toll collection process and captures an image of a person in a vehicle traveling on the road as a moving image through a windshield, the vehicle traveling on the road enters an imaging area set on the road Before, the windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road, and an image including at least the windshield portion of the vehicle traveling in the imaging area of the road as a moving image, In order to minimize the reflected light from the windshield at any angle at any vehicle position within the imaging area, And a plurality of cameras with optimized polarization angles of a polarizing filter mounted on the imaging surface side, and a windshield angle of a vehicle from among the plurality of cameras based on a windshield angle measured by the windshield angle measuring means. A camera selection unit that selects an optimal camera and acquires a moving image from the selected camera, and an image processing unit that processes the moving image acquired by the camera selection unit are provided.

  According to the present invention, it is possible to capture an image of a person such as a driver in a vehicle as a high-quality moving image by reducing the influence of the reflected light of the windshield caused by sunlight or the like even on vehicles having different windshield angles. Equipment and toll collection system can be provided.

The schematic diagram which shows roughly the structure of the fee collection system called the ETC system to which this invention is applied. FIG. 10 is a schematic diagram illustrating an application example of an imaging device. 1 is a block diagram schematically showing the configuration of an imaging apparatus according to a first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The arrangement | positioning state of each apparatus which concerns on 1st Embodiment is shown typically, (a) A figure is a side view, (b) A figure is a top view. The figure explaining the specific measuring method of the windshield angle by windshield angle measurement. The schematic diagram explaining the principle of the polarization imaging in a polarization imaging part. The schematic diagram explaining the camera selection table which concerns on 1st Embodiment. The flowchart explaining the operation | movement which concerns on 1st Embodiment. The schematic diagram explaining the camera selection table which concerns on 2nd Embodiment. The flowchart explaining the operation | movement which concerns on 2nd Embodiment. The block diagram which shows roughly the structure of the imaging device which concerns on 3rd Embodiment. The arrangement | positioning state of each apparatus which concerns on 3rd Embodiment is shown typically, (a) A figure is a side view, (b) A figure is a top view. The schematic diagram explaining the camera selection table which concerns on 3rd Embodiment. The flowchart explaining the operation | movement which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of a fee collection system called an ETC system (non-stop automatic fee collection system) to which the present invention is applied. In the example of FIG. 1, for ease of explanation, one toll collection lane (road) is shown, but the type and number of toll collection lanes are not limited to this, and a plurality of lanes are generally used. It is often provided.

  In FIG. 1, for example, a vehicle detection / vehicle type determination for detecting a vehicle 12 entering in order from the entrance side to the side of a road (toll collection lane) 11 at a toll gate of a toll road and determining the vehicle type. Device 51, roadside wireless device 52, roadside indicator 53 for providing charging information and start / stop guidance to the driver of vehicle 12, and start control device (gate) 54 for starting / stopping control of vehicle 12 Are respectively connected to the lane control device 55. The lane control device 55 is connected to a host device (host computer) 56 via a communication line.

The roadside wireless device 52 includes a roadside antenna 57 for communicating with an external wireless device, and uses narrow area wireless communication (DSRC) with the vehicle-mounted device 58 mounted on the vehicle 12. Data is transmitted and received by wireless communication, and vehicle-mounted device information transmitted from the vehicle-mounted device 58 is acquired and sent to the lane control device 55.
The lane control device 55 performs overall control and also performs toll collection processing and the like based on the vehicle-mounted device information sent from the roadside wireless device 52.

  In addition, an imaging device described below is installed on the side of the road 11 upstream of the start control device 54. As shown in FIG. 2, the imaging apparatus captures a driver's face image in a vehicle 12 traveling on a road 11 as a moving image with a camera 14 through a windshield 13.

FIG. 3 schematically shows the configuration of the imaging apparatus according to the first embodiment. The imaging apparatus includes a windshield angle measuring unit 21 as a windshield angle measuring unit that measures an angle of a windshield 13 of a vehicle 12 traveling on a road 11, and a vehicle 12 traveling in an imaging area set on the road 11. A vehicle position measuring unit 22 as vehicle position measuring means for measuring the position of the vehicle, and a polarization imaging unit comprising a plurality of cameras for capturing an image including at least the windshield 13 of the vehicle 12 traveling in the imaging area of the road 11 as a moving image. 23, based on the windshield angle measured by the windshield angle measuring unit 21 and the vehicle position measured by the vehicle position measuring unit 22, the windshield angle of the vehicle 12 and the vehicle from among a plurality of cameras in the polarization imaging unit 23 Select the best camera for the position and select the camera to get the video from this selected camera Camera selection section 24 as the stage and, are constituted by a data bus and an address bus 25 connects these can communicate.
To the data bus and the address bus 25, a recording device (for example, a hard disk recording device) 26 as an image processing means provided outside the imaging device is connected. The recording device 26 records the captured moving image as traffic history information, for example.

  FIG. 4 schematically shows the arrangement state of each device of the imaging apparatus. An imaging area E for imaging the vehicle 12 traveling in the direction of the arrow a is set on the road 11, and the windshield angle measuring unit 21 is arranged in the vicinity of the line 27 set in front of the imaging area E. It is installed.

  A vehicle position measuring unit 22 is disposed in front of the imaging area E with respect to the traveling direction a of the vehicle 12 and on one side of the road 11 (for example, the right side with respect to the traveling direction a of the vehicle 12). . The vehicle position measuring unit 22 is installed on a pole (supporting member) 28 having a predetermined height.

A polarization imaging unit 23 is disposed in front of the vehicle position measuring unit 22 with respect to the traveling direction a of the vehicle 12 and on one side of the road 11 (for example, the right side with respect to the traveling direction a of the vehicle 12). Yes. As will be described in detail later, the polarization imaging unit 23 includes three cameras 14a, 14b, and 14c each equipped with polarization filters 15a, 15b, and 15c, each having a height different from the road surface. In this way, it is installed on a pole (support member) 29.
Hereinafter, the camera 14a may be simply referred to as the camera 1, the camera 14b may be simply referred to as the camera 2, and the camera 14c may be simply referred to as the camera 3.

Hereinafter, each part will be described in detail.
The windshield angle measuring unit 21 measures the angle of the windshield 13 by, for example, imaging the traveling vehicle 12 with a camera from its side. Hereinafter, a specific method of measuring the windshield angle using the camera will be described. When the vehicle 12 is imaged from the side with a camera installed on the side of the road 11, an image as shown in FIG. 5A is obtained. Using the obtained captured image as an original image, the following image processing is performed.

  First, a binarized image as shown in FIG. 5B is obtained by performing binarization processing on the original image in FIG. 5A using an appropriate threshold value. Next, edge detection processing as shown in FIG. 5C is obtained by performing edge detection processing on the binarized image shown in FIG. 5B. Next, in the obtained edge detection image of FIG. 5C, an edge (line) 13a having a certain length 32 is detected in a certain area 31 that is considered to be the position of the windshield 13 of the vehicle 12. Then, the windshield angle is measured by calculating the angle θa of the line 13a with respect to the horizontal line 33.

  Note that the windshield angle measurement method is not limited to the above-described measurement method using the camera, and can be realized by using, for example, a known laser radar. That is, the distance to the vehicle 12 is obtained by irradiating the side surface of the vehicle 12 with the laser beam from the laser unit and measuring the round trip time until the laser beam is reflected back to the side surface of the vehicle 12 and returns. The shape of the vehicle 12 is measured by two-dimensionally scanning the laser unit. Next, from the measured shape of the vehicle 12, for example, a line having a certain length is detected in a certain area that is considered to be the position of the windshield, and the angle of the line with respect to the horizontal line is calculated. Measure the glass angle.

  The vehicle position measurement unit 22 can be realized using, for example, a known laser radar. That is, by irradiating the front surface of the traveling vehicle 12 with the laser beam from the laser unit, and measuring the round trip time until the laser beam is reflected back to the front surface of the vehicle 12, The distance is obtained, and the position of the vehicle 12 is measured based on the obtained distance.

  The position measurement method of the vehicle 12 is not limited to the laser radar measurement method described above. For example, it is well known that the position can be measured three-dimensionally using millimeter wave radar or ultrasonic waves. It is feasible.

  For example, as shown in FIG. 4, the polarization imaging unit 23 includes three cameras (for example, video cameras) 14 a, 14 b, and 14 c each equipped with polarization filters 15 a, 15 b, and 15 c on the imaging surface side, and these A camera switching unit (not shown) that switches between the three cameras 14a, 14b, and 14c. Each camera 14a, 14b, and 14c reflects from the windshield 13 with respect to a specific windshield angle at a specific vehicle position. Installed and adjusted so that light is theoretically zero (0).

  Hereinafter, the principle of polarization imaging will be described in detail with reference to FIG. 6 for one of the camera configurations. There are two conditions for optimal placement of the camera 14. The first condition is that the incident light θ on the windshield 13 of the vehicle 12 becomes a Brewster angle. As is generally known, in an optically smooth substance such as glass, when light is incident at an angle called Brewster angle, the amplitude of the P wave that vibrates on the incident surface 16 of the reflected light is 0 and only the S wave is reflected. As a second condition, the polarization angle (rotation angle) Φ of the polarizing filter 15 mounted on the camera 14 side is adjusted so that no S wave passes. As a result, the S wave is blocked and the reflected light does not pass through the polarizing filter 15.

  In FIG. 6, reference numeral 17 denotes a reflective object such as the sun or clouds that is reflected (reflected) on the windshield 13.

  In this way, by adjusting the position of the camera 14 and the polarization angle of the polarizing filter 15, the amplitude of the reflected light at a specific vehicle position at a specific windshield angle can theoretically be zero.

In the present embodiment, different windshield angles θ ₁ , θ ₂ , and θ ₃ are respectively optimized at the specific vehicle position L _m , and each is equipped with polarizing filters 15a, 15b, and 15c on the imaging surface side 3 It consists of two cameras 14a, 14b, 14c. For these cameras 14a, 14b, and 14c, a camera switching unit (not shown) selects one camera based on a camera selection signal from the camera selection unit 24, and outputs a moving image.

  For example, when the recording device 26 has an input image switching function, the input images from the cameras 14a, 14b, and 14c can be switched by sending a camera selection signal directly to the recording device 26.

  The polarization filters 15a, 15b, and 15c include not only a linear polarization filter but also a circular polarization filter. Functionally, a linear polarizing filter can be used, but depending on the type of camera, there may be a filter with polarization characteristics in front of the light receiving element. In that case, it is more advantageous to use a circular polarizing filter. Become.

  The camera selection unit 24 includes, for example, a memory for storing a program and a camera selection table and a CPU (Central Processing Unit) for executing the program, and measures the windshield angle and vehicle position measured by the windshield angle measurement unit 21. The vehicle position measured by the unit 22 is input, and an optimal camera selection signal is output using a camera selection table as shown in FIG.

  Hereinafter, an optimal camera selection method will be described in detail. For example, as shown in FIG. 7, the camera selection table indicates an optimal camera for an arbitrary windshield angle θ and an arbitrary vehicle position L in the imaging area E. In the example of FIG. 7, the windshield angle θ and the vehicle position L are continuously displayed, but an actual camera selection table is constructed with a certain resolution. For example, the windshield angle θ is set every 5 degrees, and the vehicle position L is set every 50 cm. This camera selection table is previously written in a ROM (read only memory) in the camera selection unit 24, and is created as follows.

As shown in FIG. 4, three cameras 14a, 14b, and 14c having different heights with respect to the road surface are considered. The field-of-view range of each camera 14a, 14b, 14c includes the entire imaging area E. Camera 14a, 14b, 14c, the front glass angle theta _1, theta _2, relative theta _3, the vehicle position of the central portion _{L m} of the imaging area E respectively, geometrically as described in polarimetric imaging unit 23 Optimized for. Which of the cameras 14a, 14b, and 14c is optimal for an arbitrary windshield angle and vehicle position is closest to the geometrical optimal condition described in the polarization imaging unit 23. Judgment can be made using the index. In addition, the method of creating by carrying out the experiment which changed the vehicle position with respect to the vehicle 12 of several windshield angles is also considered.

  In this way, the optimum camera selection signal obtained using the camera selection table uses, for example, 2 bits, and 0 (camera 1), 1 (camera) for the three cameras 14a, 14b, and 14c. 2) 2 (camera 3) and 3 (no output) are assigned and sent to the polarization imaging unit 23.

Next, the operation of the above configuration will be described with reference to the flowchart shown in FIG.
As shown in FIG. 4, a face image of a person (driver) boarding the vehicle 12 within a predetermined imaging area E is captured as a moving image through the windshield, and is recorded as, for example, traffic history information. Think about the case.

When the vehicle position measuring unit 22 measures that the traveling vehicle 12 has arrived at the line 27 in front of the imaging area E (step S1), the windshield angle measuring unit 21 also in front of the imaging area E measuring the angle theta of the windshield 13 of the vehicle 12 (step S2), and for example, a measurement of the angle theta ₄ results.

Then, the camera selection unit 24 starts selecting an optimal camera according to the camera selection table as shown in FIG. 7 (step S3). According to FIG. 7, the optimal camera at the imaging area start position L _s at the windshield angle θ ₄ is the camera 1 (camera 14a) (step S4).

Vehicle position measuring unit 22 starts measuring the position of the vehicle 12 to travel (step S5), and the vehicle 12 continues to determine whether arrived at the imaging area start position L _s (step S6). When the vehicle 12 is determined that it has arrived at the imaging area start position L _s, i.e. if the vehicle 12 has entered the imaging area E, the camera selection unit 24 generates a signal for selecting the camera 1 in the polarization image capturing section 23 Thus, the polarization imaging unit 23 selects the camera 1 and captures a face image of a person (driver) riding on the vehicle 12 as a moving image through the windshield (step S7). The moving image picked up by the camera 1 is sent to the recording device 26 and recording is started.

Vehicle position measuring unit 22 continues the measurement of the position of the vehicle 12 to travel (step S8), and when the vehicle 12 is determined that it has arrived at the position L _t (step S9), and in this case, the vehicle 12 is still capturing area Since E has not exited (step S10), the process returns to step S3, and the camera selection unit 24 starts selecting the optimum camera again. According to FIG. 7, the optimal camera at the vehicle position L _t at the windshield angle θ ₄ is the camera 2 (camera 14b) (step S4).

Thereafter, the same processing (steps S11 to S16) as the processing of steps S5 to S10 described above is performed, whereby the moving image captured by the camera 2 is recorded.
When the camera 3 (camera 14c) is selected in step S4, the same processing (steps S17 to S22) as the above-described steps S5 to S10 is performed, so that the moving image captured by the camera 3 is processed. Recording is performed.

Thereafter, when the vehicle position measuring unit 22, when the vehicle 12 is to measure the passing through the imaging area end position _{L e} (step S10, S16, S22), i.e., that the vehicle 12 has exited the imaging area E, the video The imaging process ends.

  Through the operations described above, the camera is always picked up by the optimal camera, and even in vehicles with different windshield angles, the influence of the reflected light of the windshield due to sunlight, etc. is reduced and driving in the vehicle is performed. A person's face image can be captured as a high-quality moving image.

Next, an imaging apparatus according to the second embodiment will be described.
Since the configuration of the imaging apparatus according to the second embodiment is substantially the same as that of the first embodiment (FIG. 3) described above, illustration is omitted, but the processing content of the camera selection unit 24 is different. Only that part is described.

  In the first embodiment, the camera selection unit 24 always selects an optimal camera from a plurality of cameras. However, the camera selection unit 24 is a particularly effective part of a moving image for the purpose of reducing the capacity of a recording memory or a hard disk. You may only want to record or process images. In that case, for example, it is possible to realize by selecting a portion where the combination of the vehicle position and the camera is close to the optimum value using a camera selection table as shown in FIG.

According to FIG. 9, for example, when the windshield angle is θ4, only the range from the vehicle positions L1 to L2 is set as the imaging area of the camera 1, so that a moving image with a slightly reflected light around the camera switching is placed in the subsequent stage. It can be prevented from flowing.
In addition, referring to the camera selection table of FIG. 9, when the windshield angle is θ6, it is also a feature of the second embodiment that there are two shooting opportunities for the moving image of the camera 2 and the camera 3 in one vehicle. .

The operation will be described below with reference to the flowchart shown in FIG.
When the vehicle position measuring unit 22 measures that the vehicle 12 has arrived at the line 27 in front of the imaging area E (step S31), the windshield angle measuring device 21 also in front of the imaging area E the angle of the windshield 13 as measured in (step S32), for example, a measurement of the angle theta ₄ results.

Then, the camera selection unit 24 starts selecting the optimum camera according to the camera selection table as shown in FIG. 9 (step S33). According to FIG. 9, when the windshield angle theta _4, the imaging area in the range of the vehicle position L1 to L2, the optimum camera is a camera 1 (camera 14a) (step S34).

  The vehicle position measurement unit 22 starts measuring the position of the vehicle 12 (step S35) and continues to measure whether or not the vehicle 12 has arrived at the position L1 (step S36). When measuring that the vehicle 12 has arrived at the position L1, the camera selection unit 24 generates a signal for selecting the camera 1 in the polarization imaging unit 23, whereby the polarization imaging unit 23 selects the camera 1 and A face image of the person (driver) on board is captured as a moving image through the windshield (step S37). The moving image picked up by the camera 1 is sent to the recording device 26 and recording is started.

  The vehicle position measurement unit 22 continues to measure the position of the vehicle 12 (step S38), and measures that the vehicle 12 has passed the position L2 (step S39). In this case, the vehicle 12 still leaves the imaging area E. Since it has not (step S40), it returns to step S33 and the camera selection part 24 starts selection of the optimal camera again (step S34).

When the camera 2 (camera 14b) is selected in step S34, the same process (steps S41 to S46) as the processes in steps S35 to S40 described above is performed, so that the moving image captured by the camera 2 is processed. Recording is performed.
When the camera 3 (camera 14c) is selected in step S34, the same process (steps S47 to S52) as the processes of steps S35 to S40 described above is performed, so that the moving image captured by the camera 3 is processed. Recording is performed.

Thereafter, when the vehicle position measuring unit 22, when the vehicle 12 is to measure the passing through the imaging area end position _{L e} (step S40, S46, S52), i.e., that the vehicle 12 has exited the imaging area E, the video The imaging process ends.

  Through the operation described above, in addition to the same effects as those of the first embodiment, it is possible to acquire a moving image only in a range where a good moving image can be obtained, and a low capacity of a recording medium (hard disk or the like) in the recording device 26 Can be realized.

Next, an imaging apparatus according to a third embodiment will be described.
The same parts as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 11 schematically illustrates the configuration of an imaging apparatus according to the third embodiment. This imaging apparatus is a windshield angle measuring means for measuring the angle of the windshield 13 of the vehicle 12 traveling on the road 11 and a vehicle position detecting means for detecting the vehicle 12 entering the imaging area set on the road 11. Based on the windshield angle measured by the vehicle measurement unit 41, the polarization imaging unit 23, and the windshield angle measurement unit 21, the optimal measurement is performed with respect to the windshield angle of the vehicle 12 from among a plurality of cameras in the polarization imaging unit 23. A camera selection unit 42 as a camera selection unit that selects a camera and acquires a moving image from the selected camera, a time measurement unit 43 that measures a time for setting an imaging area, and a data bus that connects these to be communicable An address bus 25 is used.

FIG. 12 schematically shows the arrangement state of each device. An imaging area E for imaging the vehicle 12 traveling in the direction of the arrow a is set on the road 11, and the imaging area end position _Le is set by a timer of the time measuring unit 43. Vehicle measuring section 41 is disposed in the vicinity of the imaging area start position L _s.

Hereinafter, each part will be described in detail.
The vehicle measurement unit 41 has two functions of measuring the windshield angle of the traveling vehicle 12 and detecting passage, and the windshield angle measurement function is the windshield angle measurement unit 21 used in the first embodiment described above. The vehicle passage detection function has the same configuration as that of the vehicle position measurement unit 22 used in the first embodiment described above.

  It is also possible to realize both the windshield angle measurement function and the vehicle passage detection function with the same configuration as the vehicle position measurement unit 22 used in the first embodiment described above. That is, the distance to the vehicle 12 is obtained by irradiating the side surface of the vehicle 12 with the laser beam from the laser unit and measuring the round trip time until the laser beam is reflected back to the side surface of the vehicle 12 and returns. Since the shape of the vehicle 12 can be measured by two-dimensionally scanning the laser unit, the angle of the windshield can be measured from the measured shape of the vehicle 12, and the vehicle 12 can be measured by measuring the distance from the side surface of the vehicle 12. Can be detected.

The camera selection unit 42 is similar to the camera selection unit 24 of the first embodiment described above, except that the position information of the vehicle 12 is not used.
That is, the camera selection unit 42 includes, for example, a memory that stores a program and a camera selection table and a CPU that executes the program. The camera selection unit 42 receives a windshield angle measured by the vehicle measurement unit 41 as an input, and the camera as shown in FIG. An optimal camera selection signal is output using the selection table. Compared with the first embodiment (FIG. 7), the third embodiment is characterized in that the camera switching does not depend on the vehicle position.

  Hereinafter, an optimal camera selection method will be described in detail. For example, as shown in FIG. 13, the camera selection table indicates an optimal camera for an arbitrary windshield angle θ and an arbitrary vehicle position L in the imaging area E. In the example of FIG. 13, the windshield angle θ and the vehicle position L are continuously displayed, but an actual camera selection table is constructed with a certain resolution. For example, the windshield angle θ is set every 5 degrees, and the vehicle position L is set every 50 cm. This camera selection table is previously written in the ROM in the camera selection unit 42, and is created as follows.

As shown in FIG. 12, three cameras 14a, 14b, and 14c having different heights with respect to the road surface are considered. The field-of-view range of each camera 14a, 14b, 14c includes the entire imaging area E. Camera 14a, 14b, 14c, the front glass angle theta _1, theta _2, relative theta _3, the vehicle position of the central portion _{L m} of the imaging area E respectively, geometrically as described in polarimetric imaging unit 23 Optimized for. For any windshield angle, for which the best one of the cameras 1 to 3, for example, in the central portion L _m of the imaging area E, the geometric optimal conditions described in the polarization image capturing section 23, in which camera This can be determined using an index indicating whether the photographed image is closest.
Incidentally, by performing an experiment arranged vehicle located in central L _m of the imaging area E with respect to the vehicle 12 of a plurality of windshield angle, also conceivable to create.

  In this way, the optimum camera selection signal obtained using the camera selection table uses, for example, 2 bits, and 0 (camera 1), 1 (camera) for the three cameras 14a, 14b, and 14c. 2) 2 (camera 3) and 3 (no output) are assigned and sent to the polarization imaging unit 23.

  The time measuring unit 43 includes, for example, a memory that stores a program and a CPU that executes the program. The time measuring unit 43 can be realized by executing a program whose signal polarity changes after a predetermined time. More specifically, the above-described soft timer is activated by a signal synchronized with the start of imaging of the camera and the “1” level imaging permission signal is output, and after a predetermined time has elapsed, The imaging area E can be set by outputting a “0” level imaging inhibition signal.

Next, the operation of the above configuration will be described with reference to the flowchart shown in FIG.
Vehicle measurement unit 41, the vehicle 12 detects that it has arrived at the imaging area start position _{L s} (step S61), measuring the angle of the windshield 13 of the vehicle 12 (step S62), for example, that the angle theta ₄ Assume that a measurement result is obtained.

Then, the camera selection unit 42 starts selecting the optimum camera according to the camera selection table as shown in FIG. 13 (step S63). According to FIG. 13, the optimal camera at the windshield angle θ ₄ is the camera 1 (camera 14a) (step S64).

  The camera selection unit 42 generates a signal for selecting the camera 1 in the polarization imaging unit 23, whereby the polarization imaging unit 23 selects the camera 1, and the face image of the person (driver) boarding the vehicle 12 is converted into a moving image. Then, an image is taken through the windshield (step S65). The moving image picked up by the camera 1 is sent to the recording device 26 and recording is started.

  Simultaneously with the start of imaging by the camera 1, a timer synchronized with the start of imaging is sent to the time measuring unit 43 to start the timer of the time measuring unit 43 (step S65), and a predetermined time set in advance in the timer When the time has elapsed (step S66), the imaging prohibition signal is sent to the polarization imaging unit 23 and the recording device 26, thereby completing the imaging and recording processing.

When the camera 2 (camera 14b) is selected in step S64, the same processing (steps S67 to S68) as the processing in steps S65 to S66 described above is performed, so that the moving image captured by the camera 2 is processed. Recording is performed.
If the camera 3 (camera 14c) is selected in step S64, the same process (steps S69 to S70) as the processes in steps S65 to S66 described above is performed, so that the moving image captured by the camera 3 is processed. Recording is performed.

  By the operation described above, the same effect as that of the first embodiment can be expected.

  In the third embodiment, the method for efficiently recording using the timer has been described. However, when continuously recording, the time measuring unit 43 is omitted and the vehicle 12 is detected. A configuration is also possible in which imaging is continued with the same camera until the next vehicle 12 arrives.

  In the above-described embodiment, the description has been made by arranging three cameras as the polarization imaging unit 23. However, when the range of the windshield angle to be satisfied is known in advance, the number of cameras should be reduced. Is possible.

Also, depending on the performance of the camera and the polarizing filter, there may be cases where the number of cameras is less than three or more.
Furthermore, in the above-described embodiment, an image from the camera is selected and recorded, but image processing such as extracting and recognizing a human face image may be provided as a subsequent configuration. Also in this case, there is an effect that the load of image processing can be reduced by selecting an optimal camera.

  DESCRIPTION OF SYMBOLS 11 ... Road, 12 ... Vehicle, 13 ... Windshield, 14, 14a, 14b, 14c ... Camera, 15, 15a, 15b, 15c ... Polarizing filter, 16 ... Incident surface, 21 ... Windshield angle measuring part (windshield angle) Measuring means), 22 ... Vehicle position measuring section (vehicle position measuring means), 23 ... Polarized imaging section, 24 ... Camera selecting section (camera selecting means), 26 ... Recording device (image processing means), 41 ... Vehicle measuring section ( Windshield angle measuring means, vehicle position detecting means), 42 ... camera selecting section (camera selecting means), 43 ... time measuring section, E ... imaging area, 51 ... vehicle detecting / vehicle type discriminating apparatus, 52 ... roadside radio apparatus, 54 ... Start control device (gate), 55 ... lane control device, 56 ... high-order device (host computer), 57 ... roadside antennas 57, 58 ... on-vehicle equipment.

Claims (5)

Windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road;
Vehicle position measuring means for measuring the position of the vehicle traveling in the imaging area of the road;
An image including at least a windshield portion of a vehicle traveling in the imaging area of the road is captured as a moving image, and reflected light from a windshield at an arbitrary angle at an arbitrary vehicle position in the imaging area is minimized. In order to achieve this, a plurality of cameras that optimize the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side,
Based on the windshield angle measured by the windshield angle measuring means and the vehicle position measured by the vehicle position measuring means, an optimum camera for the vehicle windshield angle and the vehicle position is selected from the plurality of cameras. Camera selection means for selecting and obtaining a video from the selected camera;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the camera selection unit acquires a moving image only in a predetermined vehicle position range determined in advance from the selected optimal camera. Windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road;
An image including at least a windshield portion of a vehicle traveling in the imaging area of the road is captured as a moving image, and reflected light from a windshield at an arbitrary angle at an arbitrary vehicle position in the imaging area is minimized. In order to achieve this, a plurality of cameras that optimize the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side,
Based on the windshield angle measured by the windshield angle measuring means, a camera selection means for selecting an optimum camera for the windshield angle of the vehicle from the plurality of cameras and acquiring a moving image from the selected camera. When,
An imaging apparatus comprising: At the toll road toll booth, the toll collection processing for the vehicle is performed by wireless communication with the vehicle-mounted device mounted on the vehicle entering the toll road road, and the vehicle runs on the road. In the toll collection system that takes images of people in the vehicle as a video through the windshield,
Windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road;
Vehicle position measuring means for measuring the position of the vehicle traveling in the imaging area of the road;
An image including at least a windshield portion of a vehicle traveling in the imaging area of the road is captured as a moving image, and reflected light from a windshield at an arbitrary angle at an arbitrary vehicle position in the imaging area is minimized. In order to achieve this, a plurality of cameras that optimize the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side,
Based on the windshield angle measured by the windshield angle measuring means and the vehicle position measured by the vehicle position measuring means, an optimum camera for the vehicle windshield angle and the vehicle position is selected from the plurality of cameras. Camera selection means for selecting and obtaining a video from the selected camera;
Image processing means for processing the moving image acquired by the camera selection means;
A toll collection system characterized by comprising: At the toll road toll booth, the toll collection processing for the vehicle is performed by wireless communication with the vehicle-mounted device mounted on the vehicle entering the toll road road, and the vehicle runs on the road. In the toll collection system that takes images of people in the vehicle as a video through the windshield,
Windshield angle measuring means for measuring the angle of the windshield of the vehicle traveling on the road before the vehicle traveling on the road enters the imaging area set on the road;
An image including at least a windshield portion of a vehicle traveling in the imaging area of the road is captured as a moving image, and reflected light from a windshield at an arbitrary angle at an arbitrary vehicle position in the imaging area is minimized. In order to achieve this, a plurality of cameras that optimize the polarization angle of the polarizing filter mounted on the installation position and the imaging surface side,
Based on the windshield angle measured by the windshield angle measuring means, a camera selection means for selecting an optimum camera for the windshield angle of the vehicle from the plurality of cameras and acquiring a moving image from the selected camera. When,
Image processing means for processing the moving image acquired by the camera selection means;
A toll collection system characterized by comprising:

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