JP2017054408A - Vehicle type determination device, vehicle type determination method, vehicle type determination program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in determination whether a two-wheel vehicle whose image has been captured in a frame image is a vehicle type that is not permitted to run on an arterial high standard highway.SOLUTION: A frame image in which an image of the rear part of a two-wheel vehicle is captured by a visible-light camera 2 is input to a visible-light image input part 12. A visible-light image processing part 14 processes the frame image input to the visible-light image input part 12, and detects a character relating to a registration symbol shown on a number plate. In addition, using at least the position where characters relating to the registration symbol shown on the number plate or the size ratio between the characters relating to the registration symbol, the visible-light image processing part 14 determines from the detection result whether the two-wheel vehicle whose image has been captured in the frame image input by the visible-light image input part 12 is a vehicle type that is not permitted to run on an arterial high standard highway or not.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for determining whether or not a motorcycle is a vehicle type (displacement of 125 cc or less) that is not permitted to travel on a high-standard highway (such as a high-speed automobile national road or a general automobile road).

  Conventionally, a frame image obtained by imaging the rear part of a traveling motorcycle is processed, and the motorcycle imaged in the frame image is permitted to travel on a high-standard highway (such as a highway automobile national road or a general national automobile road). There has been a technique for determining whether or not the vehicle type (a motorcycle with a displacement of 125 cc or less) (see Patent Document 1).

  In Patent Document 1, a license plate is extracted from a frame image obtained by imaging the rear part of a traveling motorcycle. If the width of the license plate is less than a predetermined length (less than 200 mm), the displacement is 125 cc. It is the structure determined to be the following.

  Motorcycles with a displacement of 125 cc or less and motorcycles with a displacement of more than 125 cc are not only set at the boundary of permission / prohibition of driving on high-standard trunk roads under the Road Traffic Law, but are not high-standard trunk roads. In roads, parking lots, etc., there is a case where it is set as one boundary when the usage fee is determined in stages. For this reason, not only a system that prevents motorcycles with a displacement of 125 cc or less from entering the high standard trunk road accidentally, but also tolls for toll roads that are not high standard trunk roads, parking lots, etc. are collected. Utilization of a technique for automatically determining whether or not a motorcycle has a displacement of 125 cc or less in various systems such as a system has been studied.

JP-A 64-37699

  However, in the configuration described in Patent Document 1, the size of the license plate on the frame image changes due to a change in the relative position of the two-wheeled vehicle and the camera. For this reason, it is impossible to accurately determine the width of the license plate from the frame image obtained by imaging the rear part of the motorcycle, and it is erroneously determined that a motorcycle with a displacement of 125 cc or less is a motorcycle with a displacement of more than 125 cc. In some cases, a motorcycle having an exhaust amount exceeding 125 cc is erroneously determined as a motorcycle having an exhaust amount of 125 cc or less. For this reason, there is a demand for improved accuracy in determining whether or not the motorcycle has a displacement of 125 cc or less.

  An object of the present invention is to provide a technique that improves the determination accuracy of whether or not a two-wheeled vehicle captured in a frame image is a vehicle type that is not permitted to travel on a high-standard trunk road.

  In order to achieve the above object, the vehicle type identification device of the present invention is configured as follows.

  A frame image obtained by capturing the rear part of the motorcycle is input to the image input unit. The character detection unit processes the frame image input to the image input unit, and detects a character related to the registered symbol written on the license plate. The registered symbols written on the license plate include a use symbol, a classification symbol, a series symbol, and a registered place name symbol. The usage symbol is a symbol indicating the usage of the vehicle, and is usually a single hiragana character (in exceptional cases, it may be a single alphabetic character). The classification symbol is a symbol indicating the classification of the vehicle, and is usually one or more digits. A series of symbols is usually a maximum of 4 digits (exceptionally there are 5 digits or more, or a combination of alphabets and numbers). The registered place name symbol is a symbol indicating the registered place of the vehicle, and is hiragana, kanji, alphabet, or the like.

  The determination unit, from the detection result of the character by the character detection unit, using at least one of the character notation position on the registration symbol written on the license plate, or the ratio of the size between the characters on the registration symbol, It is determined whether or not the two-wheeled vehicle captured in the frame image input to the image input unit is a vehicle type that is not permitted to travel on a high-standard trunk road.

  The high-standard arterial road referred to here is a highway automobile national road or a general national highway car-only road. According to the current road traffic law, a motorcycle with a displacement of 125 cc or less is not permitted to travel on a high-standard trunk road. That is, the determination unit determines whether or not the displacement of the two-wheeled vehicle captured in the frame image input to the image input unit is 125 cc or less.

  Note that the determination unit may determine that a motorcycle that has not been determined to have a displacement of 125 cc or less is a motorcycle that has a displacement of more than 125 cc, or may not be able to determine.

  There is a difference in the notation of the registration symbol on the license plate between a two-wheeled vehicle whose displacement is 125 cc or less and a two-wheeled vehicle whose displacement exceeds 125 cc. For example, the usage symbol differs in the notation position on the license plate. The classification symbol is not shown on the number plate of a motorcycle with a displacement of 125 cc or less, but is shown on the number plate of a motorcycle with a displacement of more than 125 cc. Also, the series symbol (in the case of 4 digits) is different in the character size of the upper 2 digits and the character size of the lower 2 digits in the case of a two-wheeled vehicle whose displacement is 125 cc or less, but the displacement exceeds 125 cc. In the case of a motorcycle, the upper two-digit character size is the same as the lower two-digit character size. Further, the ratio between the character size of the registered place name code and the last two digits of the serial number is different between a two-wheeled vehicle having a displacement of 125 cc or less and a two-wheeled vehicle having a displacement exceeding 125 cc.

  As described above, the determination unit uses at least one of the notation position of the character according to the registration symbol written on the license plate or the ratio of the size between the characters according to the registration symbol, so that the high standard trunk road Since it is determined whether or not the vehicle type is not permitted to travel, it is not affected by a change in the relative position between the two-wheeled vehicle and the camera. Therefore, it is possible to improve the determination accuracy of whether or not the two-wheeled vehicle captured in the frame image is a vehicle type that is not permitted to travel on a high-standard trunk road.

  In addition, a frame width estimation unit that processes the frame image input to the image input unit and estimates the width of the license plate is provided, and the license plate width estimated by the width estimation unit is also used to input the image plate to the image input unit. Alternatively, the determination unit may determine whether the two-wheeled vehicle captured in the frame image is a vehicle type that is not permitted to travel on the high-standard trunk road. If comprised in this way, the further improvement of the determination precision whether the two-wheeled vehicle imaged by the frame image is a vehicle model which is not permitted to drive | work on a high standard trunk road can be aimed at.

  According to the present invention, it is possible to improve the determination accuracy of whether or not the two-wheeled vehicle captured in the frame image is a vehicle type that is not permitted to travel on a high-standard trunk road.

It is the schematic which shows the structure of a false approach detection system. It is a figure which shows the structure of the principal part of a vehicle type discrimination device. FIG. 3 (A) is a diagram showing a license plate of a two-wheeled vehicle having an exhaust amount exceeding 125 cc, and FIG. 3 (B) is a diagram showing a license plate of a two-wheeled vehicle (excluding a bicycle) having an exhaust amount of 125 cc or less. . It is a flowchart which shows operation | movement of a vehicle type discrimination | determination apparatus. It is a flowchart which shows a motorcycle classification determination process. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by a classification symbol. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by a use symbol. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by the character height of a serial number. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by the character height of a serial number, and the character height of a registration place name symbol. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by the magnitude | size of a license plate. It is a flowchart which shows the classification determination process of the two-wheeled vehicle by the character height of a serial number concerning another example.

  Hereinafter, an erroneous entry detection system using a vehicle type identification device according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic diagram showing a configuration of an erroneous entry detection system according to this example. The erroneous entry detection system according to this example includes a vehicle type identification device 1, a visible light camera 2, and a far-infrared camera 3 that are embodiments of the present invention. The visible light camera 2 and the far-infrared camera 3 travel on an inflow path from a general road to a toll gate of a highway automobile national highway or a general national highway automobile-only road (corresponding to a high-standard trunk road in this invention). It is installed in the direction to image the rear of the vehicle. The visible light camera 2 is a camera that captures a visible light image, and the far infrared camera 3 is a camera that captures a far infrared image.

  As shown in FIG. 1, the visible light camera 2 has a smaller imaging area than the far-infrared camera 3. That is, in the frame image captured by the visible light camera 2, the ratio of the license plate attached to the rear portion of the vehicle is relatively large. Thereby, the recognition accuracy of the character concerning the registration symbol written on the license plate imaged by the frame image is ensured without increasing the resolution of the visible light camera 2.

  The visible light camera 2 and the far-infrared camera 3 may capture moving images at a frame rate of about several tens of frames / second (10 to 30 frames / second), or from an external device (not shown). A still image may be taken in response to the input of the release signal. This external device has, for example, a moving body detection unit that detects a moving body located within the imaging area of the visible light camera 2, and when the moving body is detected by the moving body detection unit, a release signal is sent to the visible light camera 2 or any configuration that outputs to the far-infrared camera 3.

  Note that one of the visible light camera 2 and the far-infrared camera 3 may capture a moving image, and the other may capture a still image. In this example, it is assumed that the visible light camera 2 and the far infrared camera 3 capture a moving image.

  The vehicle type identification device 1 processes the visible light frame image captured by the visible light camera 2 and the far infrared frame image captured by the far infrared camera 3, and the type of the moving body located in the inflow path is a four-wheeled vehicle, an exhaust Two-wheeled vehicles exceeding 125cc (two-wheeled vehicles that are not prohibited from traveling on high-standard arterial roads in the present invention), two-wheeled vehicles having displacement of 125cc or less (excluding bicycles) (traveling on high-standard arterial roads referred to in this invention are prohibited A two-wheeled vehicle), a bicycle, or a pedestrian. Further, the vehicle type identification device 1 outputs the determined type of the moving body to an alarm device (not shown). For example, the alarm device displays a message or the like corresponding to the type of the moving body determined by the vehicle type identification device 1 on a display provided in front of the interchange. Specifically, when the type of the moving body determined by the vehicle type identification device 1 is any one of a two-wheeled vehicle (excluding a bicycle), a bicycle, or a pedestrian whose displacement is 125 cc or less, a warning of entry prohibition is given. Display a message.

  FIG. 2 is a diagram illustrating a configuration of a main part of the vehicle type identification device according to this example. The vehicle type identification device 1 includes a control unit 11, a visible light image input unit 12, a far infrared image input unit 13, a visible light image processing unit 14, a far infrared image processing unit 15, and an output unit 16. ing.

  The control unit 11 controls the operation of each part of the vehicle type identification device 1 main body.

  A visible light camera 2 is connected to the visible light image input unit 12, and a visible light frame image captured by the visible light camera 2 is input. The visible light image input unit 12 corresponds to the image input unit referred to in the present invention.

  The far-infrared image input unit 13 is connected to the far-infrared camera 3, and a far-infrared frame image captured by the far-infrared camera 3 is input thereto.

  The visible light image processing unit 14 is a two-wheeled vehicle having a displacement of more than 125 cc by processing the visible light frame image input to the visible light image input unit 12 and recognizing a registration symbol written on the license plate. Or a motorcycle (excluding a bicycle) having a displacement of 125 cc or less. The visible light image processing unit 14 includes a configuration according to the present invention that is related to a character detection unit, a width estimation unit, and a determination unit. Moreover, the visible light image processing unit 14 executes the vehicle type identification method according to the present invention. Further, the visible light image processing unit 14 includes a computer that executes the vehicle type identification program according to the present invention.

  The far-infrared image processing unit 15 processes the far-infrared frame image input to the far-infrared image input unit 13 and determines whether or not the moving body being imaged is a four-wheeled vehicle. Further, the far-infrared image processing unit 15 is a moving body that is determined not to be a four-wheeled vehicle, and the visible light image processing unit 14 is determined not to be a two-wheeled vehicle other than a bicycle (a two-wheeled vehicle with a displacement exceeding 125 cc, or For a two-wheeled vehicle with a displacement of 125 cc or less (excluding a bicycle), it is determined whether the moving member is a bicycle or a pedestrian.

  As is clear from the above description, the visible light image processing unit 14 determines whether or not the moving body imaged in the visible light frame image input to the visible light image input unit 12 is a two-wheeled vehicle excluding a bicycle. Also do.

  The output unit 16 is a warning that the type of the determined moving body (four-wheeled vehicle, two-wheeled vehicle with a displacement of more than 125 cc, two-wheeled vehicle with a displacement of 125 cc or less (except a bicycle), bicycle, or pedestrian) is connected. Output to the device.

  Here, referring to FIG. 3, traveling on a motorcycle with a displacement exceeding 125 cc that is not prohibited from traveling on a highway automobile national road or a general national automobile road, and on a highway automobile national road or a general national automobile road, etc. The difference in the notation of the registration symbol on the license plate between a motorcycle (excluding a bicycle) with a displacement of 125 cc or less that is prohibited is described. FIG. 3 (A) is a diagram showing a license plate of a two-wheeled vehicle having an exhaust amount exceeding 125 cc, and FIG. 3 (B) is a diagram showing a license plate of a two-wheeled vehicle (excluding a bicycle) having an exhaust amount of 125 cc or less. . On a license plate of a motorcycle having a displacement of more than 125 cc, a classification symbol, a registered place name symbol, an application symbol, and a serial number (corresponding to the serial symbol in the present invention) are written as registration symbols. On the other hand, a registration place name symbol, a use symbol, and a serial number are written as registration symbols on a license plate of a motorcycle (excluding a bicycle) having a displacement of 125 cc or less. In this example, a classification symbol, a registered place name symbol, a usage symbol, and a serial number are referred to as registered symbol attributes written on the license plate. Also, in this example, as shown below, the ratio of the size (character height in this example) between the character whose attribute is the registered place name symbol and the character whose attribute is the serial number, and the attribute is the serial number The ratio of the size (in this example, the character height) between the lower 2nd character that is and the lower 3rd character whose attribute is a serial number is the distance between characters related to the registered symbol as referred to in the present invention. It corresponds to the ratio of the size of.

  The classification symbol is a symbol indicating classification such as the size of the vehicle. As shown in FIG. 3, the classification symbol is a number (in exceptional cases, it may be an alphabet), and is written on the upper left of the license plate of a two-wheeled vehicle having a displacement exceeding 125 cc. Further, no classification symbol is written on the license plate of a motorcycle (excluding a bicycle) having a displacement of 125 cc or less. Therefore, it can be determined whether the motorcycle has a displacement of more than 125 cc or a motorcycle with a displacement of 125 cc or less (excluding a bicycle) depending on whether the classification symbol is written on the upper left of the license plate.

  The use symbol is a symbol indicating the use of the vehicle (for business use, private use, etc.). As shown in FIG. 3, the usage symbol is hiragana (in some cases, it may be an alphabet as an exception). The usage symbol is shown on the upper right of the number plate for motorcycles with a displacement of more than 125 cc, and the lower left for the number plate of motorcycles (except for bicycles) with a displacement of 125 cc or less (left side of the serial number described later). It is written in. Therefore, depending on whether the position of the usage symbol on the license plate is in the upper right or lower left, it is determined whether the motorcycle is a motorcycle with a displacement exceeding 125cc or a motorcycle (excluding a bicycle) with a displacement of 125cc or less. can do.

  The registered place name symbol is a symbol indicating a place name (land transportation station or municipality) where the vehicle is registered. Registered place name symbols are kanji and hiragana. The registered place name symbol shown on the license plate of motorcycles with displacement exceeding 125cc indicates the Land Transport Bureau, and the registered place name symbol shown on the number plate of motorcycles (except bicycles) with displacement of 125cc or less is Indicates a municipality.

  The serial number is usually a maximum of 4 digits (exceptionally, there are 5 digits or more, or a combination of alphabets and numbers). The serial numbers written on the number plate of a motorcycle with a displacement of more than 125 cc are approximately the same in size. On the other hand, in the serial number written on the number plate of a motorcycle (excluding a bicycle) with a displacement of 125 cc or less, the lower two digits are larger than the upper two digits. Therefore, depending on the ratio of the last two digits of the serial number indicated on the license plate and the upper two digits, the displacement is more than 125cc, or the displacement is less than 125cc. Whether it is a two-wheeled vehicle (except a bicycle) can be determined. For example, if the character height ratio a / b shown in FIG. 3 is larger than a predetermined value α (for example, α = 1.1), the motorcycle has a displacement of 125 cc or less (except a bicycle). Can be determined.

  In addition, the number of the last two digits of the serial number and the size of the letters for the registered place name symbol on the number plate of motorcycles with displacement greater than 125cc and motorcycles with displacement of 125cc or less (excluding bicycles) The ratio of is different. Therefore, depending on the ratio of the last two digits of the serial number and the size of the letters on the registered place name symbol, the motorcycle has a displacement of more than 125cc or a motorcycle with a displacement of less than 125cc (excluding bicycles). Can be determined. For example, if the character height ratio a / c shown in FIG. 3 is larger than a predetermined value β (for example, β = 2.0), the motorcycle has a displacement of 125 cc or less (except for a bicycle). Can be determined.

  Furthermore, the number plate of a two-wheeled vehicle with a displacement exceeding 125 cc is larger than the number plate of a two-wheeled vehicle (except for a bicycle) with a displacement of 125 cc or less. The number plate for motorcycles with displacement greater than 125cc is 230 (mm) x 125 (mm) (width x length), and the number plate for motorcycles (except bicycles) with displacement of 125cc or less is 200. The size is (mm) × 100 (mm) (horizontal × vertical). Therefore, it is possible to determine whether the number plate is a two-wheeled vehicle with a displacement exceeding 125 cc or a two-wheeled vehicle (excluding a bicycle) with a displacement of 125 cc or less. For example, if the width of the license plate is less than 210 mm, it can be determined that the motorcycle is a two-wheeled vehicle (excluding a bicycle) with a displacement of 125 cc or less.

  In addition to the license plate shown in Fig. 3, there are license plates (so-called local numbers) whose external shapes and registered symbols are changed according to the characteristics of the region. In this case, there is at least one of the above-described difference in the license plate between a motorcycle with a displacement exceeding 125 cc and a motorcycle with a displacement of 125 cc or less (except for a bicycle).

  Hereinafter, the operation of the vehicle type identification device 1 according to this example will be described. FIG. 4 is a flowchart showing the operation of the vehicle type identification device. When the vehicle type identification device 1 detects that the moving body is located within the imaging area of the visible light camera 2 (s1), it determines whether or not the width of the detected moving body exceeds a predetermined width (for example, 1 m). Determine (s2). In s1, the visible light image processing unit 14 generates a background difference image related to the visible light frame image captured by the visible light camera 2 input to the visible light image input unit 12, and detects the moving body being captured. It may be a process, or may be a process that is determined by a detection signal of a moving body input from an external device such as a vehicle detector (not shown).

  When the visible light camera 2 and the far-infrared camera 3 are configured to capture a still image, the visible light camera 2 and the far-infrared camera 3 are detected when a moving object is detected by an external device. A release signal for imaging a plurality of frames (for example, 10 frames) at a predetermined time interval (for example, 100 ms interval) may be input.

  In s2, the far-infrared image processing unit 15 processes the far-infrared frame image captured by the far-infrared camera 3 input to the far-infrared image input unit 13, and the width of the moving body detected this time is a predetermined width ( For example, it is determined whether or not 1m) is exceeded. If the width of the moving body detected this time exceeds a predetermined width, the vehicle type identification device 1 determines that the vehicle is a four-wheeled vehicle (s3).

  When the vehicle type identification device 1 determines in s2 that the far-infrared image processing unit 15 does not exceed the predetermined width, the visible light image processing unit 14 causes the visible light camera 2 to capture the visible light. It is determined whether there is a license plate at the rear of the moving body imaged in the frame image (s4). If the visible light image processing unit 14 determines that there is a license plate at the rear part of the moving body in s4, the vehicle type determination device 1 performs a motorcycle type determination process described later (s5). The two-wheeled vehicle type determination process in s5 is a process for determining whether the mobile body detected this time is a two-wheeled vehicle with an exhaust amount exceeding 125cc or a two-wheeled vehicle (excluding a bicycle) with an exhaust amount of 125cc or less.

  When the visible light image processing unit 14 determines that there is no license plate at the rear of the moving body in s4, the far-infrared camera input to the far-infrared image input unit 13 in the far-infrared image processing unit 15 3 processes the far-infrared frame image picked up and estimates the speed of the moving body (s6). In s6, the two far-infrared frame images input to the far-infrared image input unit 13 are processed, and the time difference between the imaging timings of the two far-infrared frame images and the images on the two far-infrared frame images are captured. The speed of the moving body is estimated based on the distance between the positions of the moving body.

  If the speed of the moving body estimated in s6 is equal to or higher than a predetermined speed (for example, 8 km / h), the vehicle type identification device 1 determines that the moving body detected this time is a bicycle (s7, s8). Further, the vehicle type identification device 1 determines that the moving body detected this time is a pedestrian if the speed of the moving body estimated in s6 is not equal to or higher than a predetermined speed (s7, s9).

  The vehicle type identification device 1 outputs the determination result of the type of the moving body determined in s3, s5, s8, or s9 from the output unit 16 (s10), and returns to s1. In s10, the type of the determined moving body (four-wheeled vehicle, two-wheeled vehicle with a displacement exceeding 125cc, two-wheeled vehicle with a displacement of 125cc or less (excluding bicycle), bicycle, or pedestrian) is connected to the connected alarm device. Output.

  Next, the motorcycle type determination process according to s5 will be described. FIG. 5 is a flowchart showing the motorcycle type determination process. This motorcycle type determination process is performed in the visible light image processing unit 14.

  The visible light image processing unit 14 performs recognition processing of characters written on the license plate for the visible light frame image determined to have a license plate at the rear of the moving body in s4 described above (s21). In s21, for each character written on the license plate, the position of the character, the character type, the character height of the character, and the reliability of character recognition are detected. The character position is a coordinate indicating the position on the license plate, for example, a two-dimensional coordinate with the lower left corner of the license plate as the origin. The character type is a number, hiragana, kanji, alphabet, or the like. The character height of the character is a length corresponding to a, b, and c shown in FIG. The character height of the character is the length on the visible light frame image. However, it may be converted to a length in real space. In this example, the processing load on s21 is suppressed by not calculating the length in real space for the character height of the character written on the license plate. The reliability of character recognition is an index indicating the accuracy of the recognition result, and the higher the index, the higher the reliability. For example, the reliability of character recognition is the similarity of the feature amount with the characters registered in the dictionary.

  The visible light image processing unit 14 determines the attribute of each character recognized in s21 (s22). The character attributes referred to here are a classification symbol, a registered place name symbol, a use symbol, and a serial number. In s22, the attribute is determined based on the character position and the character type. Specifically, an attribute of a character according to a numeral or alphabet located at the upper left of the license plate is determined as a classification symbol. The attribute of the character related to kanji and hiragana located at the upper center of the license plate is determined as a registered place name symbol. An attribute of a character related to a single hiragana or alphabet located on the upper right or lower left end of the license plate is determined as a use symbol. The attributes of the numbers and alphabetic characters located below the license plate are determined as serial numbers.

  The visible light image processing unit 14 performs a type determination process for the two-wheeled vehicle based on the classification symbol (s23). FIG. 6 is a flowchart showing a two-wheeled vehicle type determination process using the classification symbol according to s23.

  The visible light image processing unit 14 determines the presence / absence of the character determined to be the classification symbol in the determination of the character attribute in s22 (s41). As described above, the letters relating to the classification symbols are not written on the license plate of a motorcycle (excluding a bicycle) having a displacement of 125 cc or less.

  If the visible light image processing unit 14 determines that there is no character associated with the classification symbol, the visible light image processing unit 14 does not determine whether the motorcycle has a displacement exceeding 125 cc or a motorcycle (excluding a bicycle) having a displacement of 125 cc or less. This process is terminated. That is, the visible light image processing unit 14 does not determine that the motorcycle has a displacement of 125 cc or less (except a bicycle) even if there is no character associated with the classification symbol. As a result, in the character recognition processing for s21, when a character for the classification symbol written on the license plate is not detected or recognized for some reason, a motorcycle (excluding a bicycle) with a displacement of 125 cc or less is erroneously detected. ) Is prevented from being erroneously determined.

  When the visible light image processing unit 14 determines that there is a character related to the classification symbol, the visible light image processing unit 14 determines whether the reliability of character recognition for the character related to the classification symbol exceeds a predetermined value (s42). As described above, the reliability of character recognition is obtained in s21. When the visible light image processing unit 14 determines that the reliability of character recognition does not exceed the predetermined value, the visible light image processing unit 14 is either a two-wheeled vehicle having a displacement exceeding 125 cc or a two-wheeled vehicle having a displacement of 125 cc or less (excluding a bicycle). This process is terminated without determining whether or not. As a result, if the character whose attribute is determined to be the character related to the classification symbol in s22 is the character that was erroneously recognized in the character recognition processing related to s21, it is erroneously determined to be a motorcycle that has a displacement exceeding 125cc. Is prevented.

  When the visible light image processing unit 14 determines that the reliability of character recognition exceeds a predetermined value, the visible light image processing unit 14 determines that the motorcycle has a displacement exceeding 125 cc (s43), and ends the process.

  When the visible light image processing unit 14 finishes the above-described processing relating to s23, the visible light image processing unit 14 determines whether or not it has been determined in s43 that the motorcycle has a displacement exceeding 125 cc (s24). If the visible light image processing unit 14 determines in s43 that the motorcycle has a displacement of more than 125 cc, the process ends. If the visible light image processing unit 14 does not determine in s43 that the motorcycle has a displacement of more than 125 cc, the visible light image processing unit 14 performs a motorcycle type determination process using a use symbol (s25).

  FIG. 7 is a flowchart showing a two-wheeled vehicle type determination process using the application symbol according to s25. The visible light image processing unit 14 determines whether or not the character determined to be the use symbol is in the upper right of the license plate in the determination of the character attribute in s22 (s51). If the character determined to be a use symbol is on the upper right of the license plate, the visible light image processing unit 14 determines whether the reliability of character recognition for this character exceeds a predetermined value (s52). If the reliability of the character applied to the application symbol located at the upper right of the license plate exceeds the predetermined value in s52, the visible light image processing unit 14 is a two-wheeled vehicle with a displacement exceeding 125cc, or a two-wheeled vehicle with a displacement of 125cc or less. This process is terminated without determining which one is (except bicycle).

  When the visible light image processing unit 14 determines that the character applied to the application symbol is not located on the upper right side of the license plate in s51, or determines that the reliability of the character does not exceed the predetermined value in s52, the application symbol It is determined whether or not the character relating to is on the lower left side of the license plate (s53). If the visible light image processing unit 14 determines in s53 that the character for the application symbol is not on the lower left side of the license plate, the motorcycle with a displacement exceeding 125cc, or a motorcycle with a displacement of 125cc or less (excluding bicycles) This process is terminated without determining which of the above.

  If the visible light image processing unit 14 determines in s53 that the character related to the use symbol is on the lower left side of the license plate, it determines whether or not the reliability of character recognition for this character exceeds a predetermined value. (S54). If the reliability of the character applied to the use symbol located at the lower left end of the license plate in s54 does not exceed a predetermined value, the visible light image processing unit 14 is a motorcycle with an exhaust amount exceeding 125cc, or an exhaust amount is 125cc or less. This processing is terminated without determining which of the motorcycles (excluding bicycles). The visible light image processing unit 14 also sets a motorcycle (with the exception of a bicycle) with a displacement of 125 cc or less if the reliability of the character applied to the use symbol located at the lower left end of the license plate exceeds the predetermined value in s54. Is determined (s55), and the present process is terminated.

  When the visible light image processing unit 14 finishes the above-described processing relating to s25, if it is determined in s55 that the motorcycle is a two-wheeled vehicle (excluding a bicycle) having a displacement of 125 cc or less (excluding a bicycle), this processing is finished. If it is not determined in s55 that the motorcycle has a displacement of 125 cc or less (except for a bicycle), the visible light image processing unit 14 performs a motorcycle type determination process based on the character height of the serial number (s27).

  FIG. 8 is a flowchart showing a motorcycle type determination process based on the character height of the serial number according to s27. The visible light image processing unit 14 determines whether the serial number written on the license plate is 3 digits or more (s61). If the serial number written on the license plate is less than 3 digits (2 digits or 1 digit), the visible light image processing unit 14 is a two-wheeled vehicle with a displacement of more than 125 cc, or a motorcycle with a displacement of 125 cc or less ( This processing is terminated without determining which one is (except bicycle).

  If the serial number written on the license plate is 3 digits or more, the visible light image processing unit 14 sets the character height a of the lower second digit character and the character height b of the lower third digit character. It detects (s62, s63). The visible light image processing unit 14 determines whether the ratio (a / b) between the character height a of the lower second digit character and the character height b of the lower third character exceeds a predetermined value α. Determination is made (s64). If the ratio (a / b) between the character height a of the lower second digit character and the character height b of the lower third digit character does not exceed the predetermined value α, the visible light image processing unit 14 This process is terminated without determining whether the motorcycle has a displacement exceeding 125 cc or a motorcycle (excluding a bicycle) having a displacement of 125 cc or less. On the other hand, the visible light image processing unit 14 determines that the ratio (a / b) between the character height a of the lower second digit character and the character height b of the lower third character exceeds the predetermined value α. If it is determined that the motorcycle is a motorcycle (excluding a bicycle) with an engine displacement of 125 cc or less (s65), the process ends.

  When the visible light image processing unit 14 finishes the above-described processing relating to s27, if it is determined in s65 that the motorcycle has a displacement of 125 cc or less (excluding a bicycle) (s28), this processing ends. The visible light image processing unit 14 determines the type of the motorcycle based on the character height of the serial number and the character height of the registered place name symbol unless it is determined in s65 that the motorcycle has a displacement of 125 cc or less (excluding a bicycle). Processing is performed (s29).

  FIG. 9 is a flowchart showing a motorcycle type determination process based on the character height of the serial number and the character height of the registered place name symbol in s29. The visible light image processing unit 14 detects the character height a of the last two digits of the serial number written on the license plate and the character height c of the character applied to the registered place name symbol (s71, s72). In s71, for example, the character height a of the character is detected for a character with higher reliability of character recognition. In s72, the character height c is detected for the character having the highest character recognition reliability among the characters related to the registered place name symbol. The visible light image processing unit 14 determines whether the ratio (a / c) of the character height a of the character relating to the serial number and the character height c of the character relating to the registered place name symbol exceeds a predetermined value β. (S73). If the ratio (a / c) between the character height a of the character relating to the serial number and the character height c of the character relating to the registered place name symbol does not exceed the predetermined value β, the visible light image processing unit 14 performs exhaust. This process is terminated without determining whether the motorcycle is a motorcycle with an amount exceeding 125 cc or a motorcycle (excluding a bicycle) with an exhaust amount of 125 cc or less. On the other hand, if the ratio (a / c) of the character height a of the character relating to the serial number and the character height c of the character relating to the registered place name symbol exceeds the predetermined value β, the visible light image processing unit 14 Then, it is determined that the motorcycle has a displacement of 125 cc or less (excluding a bicycle) (s74), and the process is terminated.

  When the visible light image processing unit 14 finishes the above-described processing relating to s29, if it is determined in s74 that the motorcycle is a two-wheeled vehicle (excluding a bicycle) having a displacement of 125 cc or less (s30), the visible light image processing unit 14 ends this processing. If the visible light image processing unit 14 has not determined in s74 that the motorcycle has a displacement of 125 cc or less (excluding a bicycle), the visible light image processing unit 14 performs a motorcycle type determination process based on the size of the license plate (s31).

  FIG. 10 is a flowchart illustrating the motorcycle type determination process based on the size of the license plate according to s31. The visible light image processing unit 14 detects the imaging position of the license plate on the visible light frame image input to the visible light image input unit 12 (s81). The visible light image processing unit 14 converts the license plate position on the frame image into the position of the world coordinate system by a known perspective projection method, and calculates the lateral width of the license plate (s82). A transformation matrix (internal parameters and external parameters of the visible light camera 2) used in the perspective projection method in s82 is set when the visible light camera 2 is installed.

  If the lateral width of the license plate calculated in s82 is smaller than the predetermined width w, the visible light image processing unit 14 determines that the motorcycle has a displacement of 125 cc or less (excluding a bicycle) (s83, s84). ), This process is terminated. In addition, the visible light image processing unit 14 is a two-wheeled vehicle with a displacement exceeding 125 cc or a two-wheeled vehicle with a displacement of 125 cc or less (bicycle) unless the width of the license plate calculated in s82 is smaller than a predetermined width w. This processing is terminated without determining which of the above is excluded.

  When the visible light image processing unit 14 finishes the above-described processing relating to s31, if it is determined in s84 that the motorcycle is a two-wheeled vehicle (excluding a bicycle) having a displacement of 125 cc or less (excluding a bicycle), this processing is finished. If the visible light image processing unit 14 does not determine in s84 that the motorcycle has a displacement of 125 cc or less (except for a bicycle), it determines that the displacement exceeds 125 cc (s33), and performs this process. finish.

  As described above, the vehicle type identification device 1 according to this example has a displacement of 125 cc depending on the position of the character on the registration symbol written on the license plate, the ratio of the size between the characters on the registration symbol, and the like. It is determined whether the motorcycle exceeds 2 or the motorcycle with a displacement of 125 cc or less (excluding a bicycle). Therefore, it is determined whether or not the two-wheeled vehicle captured in the visible light frame image is a vehicle type that is not permitted to travel on a high-standard trunk road (whether it is a two-wheeled vehicle (excluding a bicycle) with a displacement of 125 cc or less). The accuracy can be improved.

  Moreover, the order of determination concerning s23, s25, s27, s29, and s31 in the motorcycle type determination process shown in FIG. 5 is not limited to the order described above, and may be performed in any order. Further, the motorcycle type determination process may be configured to perform one or more determinations regarding s23, s25, s27, and s29.

  Further, the two-wheeled vehicle type determination process based on the character height of the serial number shown in FIG. 8 may be replaced with the process shown in FIG. FIG. 11 is a flowchart showing a motorcycle type determination process based on the character height of the serial number according to another example. The visible light image processing unit 14 determines whether the serial number written on the license plate is 3 digits or more (s91). If the serial number written on the license plate is less than 3 digits (2 digits or 1 digit), the visible light image processing unit 14 is a two-wheeled vehicle with a displacement of more than 125 cc, or a motorcycle with a displacement of 125 cc or less ( This processing is terminated without determining which one is (except bicycle).

  The visible light image processing unit 14 detects the maximum value max and the minimum value min of the character height of each character if the serial number written on the license plate is 3 digits or more (s92, s93). The visible light image processing unit 14 determines whether the ratio (max / min) between the maximum character height value max and the minimum character height value min exceeds a predetermined value α (s94). If the ratio (max / min) between the maximum value max of the character height and the minimum value min of the character height does not exceed a predetermined value, the visible light image processing unit 14 This process is terminated without determining which of the motorcycles (excluding bicycles) the displacement is 125 cc or less. On the other hand, if the ratio (max / min) between the maximum value max of the character height and the minimum value min of the character height exceeds the predetermined value α, the visible light image processing unit 14 has a displacement of 125 cc or less. It determines with it being a two-wheeled vehicle (except a bicycle) (s95), and complete | finishes this process.

  In addition, in the motorcycle type determination process based on the character height of the serial number, the ratio of the character height is calculated for each combination of two adjacent characters in the serial number, and the maximum value of the calculated ratio exceeds the predetermined value α. If so, it may be determined that the motorcycle is a two-wheeled vehicle (excluding a bicycle) having a displacement of 125 cc or less.

  In this example, in order to prevent a motorcycle (excluding a bicycle) having a displacement of 125 cc or less from being erroneously determined to be a motorcycle having a displacement exceeding 125 cc, the displacement is s25, s27, and s29. If it is not determined that the motorcycle is a motorcycle of 125 cc or less (excluding a bicycle), it is not determined whether the motorcycle has a displacement of more than 125 cc or a motorcycle of 125 cc or less (except a bicycle). ing.

  In the above example, the above-described processing relating to s2 and s6 is performed by processing the far-infrared frame image captured by the far-infrared camera 3, but the visible light frame image captured by the visible-light camera 2 is processed. You may make it the structure performed by processing. If comprised in this way, the far-infrared camera 3, the far-infrared image input part 13, and the far-infrared image process part 15 can be made unnecessary. The visible light camera 2 may be replaced with a near infrared camera. By using a near-infrared camera instead of the visible light camera 2, light damage to the surroundings due to illumination light can be suppressed.

  In addition, the vehicle type identification device 1 according to the present invention is not only a system for preventing a motorcycle having a displacement of 125 cc or less from entering the high standard trunk road accidentally, but also a toll road that is not a high standard trunk road, It can also be used in systems such as a system that collects usage fees for parking lots and the like.

DESCRIPTION OF SYMBOLS 1 ... Vehicle type discrimination device 2 ... Visible light camera 3 ... Far infrared camera 11 ... Control part 12 ... Visible light image input part 13 ... Far infrared image input part 14 ... Visible light image processing part 15 ... Far infrared image processing part 16 ... Output Part

Claims (9)

An image input unit for inputting a frame image obtained by imaging the rear portion of the motorcycle;
A character detection unit that processes a frame image input to the image input unit and detects a character applied to a registration symbol written on a license plate;
From the detection result of the character by the character detection unit, using at least one of the notation position of the character applied to the registered symbol written on the license plate, or the ratio of the size between the characters applied to the registered symbol, A vehicle type identification device comprising: a determination unit that determines whether or not the two-wheeled vehicle captured in the frame image input to the image input unit is a vehicle type that is not permitted to travel on a high-standard trunk road.   The determination unit is configured such that the two-wheeled vehicle captured in the frame image input to the image input unit is a high-speed image according to a character notation position related to a use symbol included in the registration symbol on the license plate. The vehicle type identification device according to claim 1, wherein it is determined whether or not the vehicle type is not permitted to travel on a standard highway.   The determination unit is configured to calculate the image according to a ratio between a character height of a character in the last second digit of the series symbol included in the registration symbol and a character height of a character in the lower third digit of the series symbol on the license plate. The vehicle type identification device according to claim 1 or 2, wherein the two-wheeled vehicle captured in the frame image input to the input unit is a vehicle type that is not permitted to travel on a high-standard trunk road.   The determination unit is configured to input the image according to a ratio of a height of a character having a maximum height and a character having a minimum height among characters on a series of symbols included in the registration symbol on a license plate. The vehicle type identification device according to claim 1, wherein the two-wheeled vehicle imaged in the frame image input to the unit is a vehicle type that is not permitted to travel on a high-standard trunk road.   The determination unit determines the ratio of the character height of the first or second digit of the series symbol included in the registered symbol and the character height of the character applied to the registered place name symbol included in the registered symbol. The motorcycle according to any one of claims 1 to 4, wherein the motorcycle captured in the frame image input to the image input unit is a vehicle type that is not permitted to travel on a high-standard trunk road. Vehicle type identification device.   The determination unit is configured such that a two-wheeled vehicle captured in the frame image input to the image input unit is a high-standard main road depending on the presence or absence of a classification symbol indicating the classification of the vehicle included in the registration symbol on the license plate. The vehicle type discrimination device according to any one of claims 1 to 5, wherein it is determined whether or not the vehicle type is allowed to travel. A frame width input unit that processes the frame image input to the image input unit and estimates the width of the license plate,
The determination unit uses the width of the license plate estimated by the width estimation unit, and the two-wheeled vehicle captured in the frame image input to the image input unit is not permitted to travel on a high-standard trunk road. The vehicle type discrimination device according to any one of claims 1 to 6, wherein it is determined whether or not the vehicle type. A character detection step of processing a frame image obtained by imaging the rear portion of the two-wheeled vehicle, which is input to the image input unit, and detecting a character applied to the registration symbol written on the license plate;
From the detection result of the character by the character detection step, using at least one of the notation position of the character applied to the registered symbol written on the license plate, or the ratio of the size between the characters applied to the registered symbol, A vehicle type determination method comprising: a determination step of determining whether or not the two-wheeled vehicle captured in the frame image input to the image input unit is a vehicle type that is not permitted to travel on a high-standard trunk road. A character detection step of processing a frame image obtained by imaging the rear portion of the two-wheeled vehicle, which is input to the image input unit, and detecting a character applied to the registration symbol written on the license plate;
From the detection result of the character by the character detection step, using at least one of the notation position of the character applied to the registered symbol written on the license plate, or the ratio of the size between the characters applied to the registered symbol, A vehicle type determination program that causes a computer to execute a determination step of determining whether or not a motorcycle captured in a frame image input to an image input unit is a vehicle type that is not permitted to travel on a high-standard trunk road.

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