JP2001126184A - Automatic license plate recognizing device and vehicle speed measuring method - Google Patents
Automatic license plate recognizing device and vehicle speed measuring methodInfo
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- JP2001126184A JP2001126184A JP30947799A JP30947799A JP2001126184A JP 2001126184 A JP2001126184 A JP 2001126184A JP 30947799 A JP30947799 A JP 30947799A JP 30947799 A JP30947799 A JP 30947799A JP 2001126184 A JP2001126184 A JP 2001126184A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、車両の走行速度計
測機能を備えたナンバープレート自動認識装置と、その
車両速度測定方法に関し、特に、ナンバープレートの取
り付け高さに関わらず車両の走行速度を正確に計測でき
るようにしたものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a license plate automatic recognition device having a vehicle traveling speed measurement function and a vehicle speed measuring method, and more particularly to a method for measuring the traveling speed of a vehicle irrespective of the mounting height of the license plate. It is intended to be able to measure accurately.
【０００２】[0002]
【従来の技術】従来のナンバープレート自動認識装置
は、路上に架設されたビデオカメラで走行する車両の前
面部を撮像し、その画像を記憶する。そして、そのフレ
ーム画像からナンバープレートの文字を認識し、また、
２枚のフレーム画像の間で、ナンバープレートの特徴点
が移動した移動距離を求め、この２枚のフレーム画像の
撮影時間差と移動距離とから車両の走行速度を算出す
る。2. Description of the Related Art A conventional automatic license plate recognition apparatus captures an image of the front of a running vehicle with a video camera installed on the road and stores the image. Then, recognize the characters on the license plate from the frame image,
The moving distance of the feature point of the license plate moved between the two frame images is obtained, and the running speed of the vehicle is calculated from the photographing time difference and the moving distance between the two frame images.
【０００３】[0003]
【発明が解決しようとする課題】しかし、従来のナンバ
ープレート自動認識装置では、車両速度を大まかにしか
計測することができない。これは、ナンバープレートの
取り付け高さが車両によって異なるためであり、車両速
度が同じであっても、ナンバープレートの取り付け高さ
が違うと、２枚のフレーム画像の間での特徴点の移動距
離が変わってくるためである。However, a conventional automatic license plate recognition apparatus can only roughly measure the vehicle speed. This is because the mounting height of the license plate differs depending on the vehicle, and even if the vehicle speed is the same, if the mounting height of the license plate is different, the moving distance of the feature point between the two frame images Because it changes.
【０００４】そのため、従来は、送信波と受信波（反射
波）とで速度を検出するドップラー式の速度センサを路
上に別途設置し、この速度センサにより車両の正確な走
行速度を計測しているが、速度センサ用の設置スペース
が必要であり、高い設置コストが掛かり、また、センサ
ーメンテナンスが必要になるなど、多くの不利な点を有
している。For this reason, conventionally, a Doppler type speed sensor for detecting the speed of a transmitted wave and a received wave (reflected wave) is separately installed on a road, and the speed sensor measures the accurate running speed of the vehicle. However, there are many disadvantages, such as requiring an installation space for the speed sensor, increasing the installation cost, and requiring sensor maintenance.
【０００５】本発明は、こうした従来の問題点を解決す
るものであり、車両速度を高精度に検出することができ
るナンバープレート自動認識装置を提供し、また、その
車両速度測定方法を提供することを目的としている。SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and provides an automatic license plate recognizing device capable of detecting a vehicle speed with high accuracy, and a method of measuring the vehicle speed. It is an object.
【０００６】[0006]
【課題を解決するための手段】そこで、本発明では、設
定された俯角で走行車両の前面を撮像するカメラを備
え、撮影画像からナンバープレートの文字認識と車両速
度の測定とを行うナンバープレート自動認識装置におい
て、カメラの撮像範囲内の所定地点に進入した車両を感
知する感知器と、感知器が感知した時点でカメラにより
撮像された１枚目の画像を記憶する第１の画像メモリ
と、カメラが撮像した２枚目の画像を記憶する第２の画
像メモリと、各画像メモリに記録された画像から共通す
る特徴点を抽出し、そのアドレスを求める特徴抽出手段
と、各画像での特徴点のアドレスの差分から車両の移動
画素数を算出し、１枚目の画像の特徴点のアドレスから
特徴点の高さを算出し、それを基に１画素当たりの走行
距離を算出して、車両の走行速度を求める速度計測手段
とを設けている。SUMMARY OF THE INVENTION Accordingly, the present invention provides a license plate automatic camera which includes a camera for imaging the front of a traveling vehicle at a set depression angle, and performs character recognition of a license plate and measurement of a vehicle speed from a captured image. In the recognition device, a sensor that senses a vehicle that has entered a predetermined point within the imaging range of the camera, a first image memory that stores a first image captured by the camera at the time when the sensor senses, A second image memory for storing a second image picked up by the camera, a feature extracting means for extracting a common feature point from the images recorded in each image memory and obtaining an address thereof, and a feature for each image The number of moving pixels of the vehicle is calculated from the difference of the address of the point, the height of the feature point is calculated from the address of the feature point of the first image, and the traveling distance per pixel is calculated based on the calculated height. vehicle It is provided a speed measuring means for determining the running speed.
【０００７】また、本発明の車両速度測定方法では、カ
メラの撮像範囲内の所定地点に進入した車両を感知器で
感知し、感知器が感知した時点でカメラにより１枚目の
画像を撮像し、この１枚目の画像とカメラがｔ時間後に
撮像した２枚目の画像とに共通する特徴点を抽出して、
両方の画像における特徴点のアドレスを求め、各画像の
特徴点のアドレスの差分から車両の移動画素数ｎを算出
し、１枚目の画像の特徴点のアドレスｍから特徴点の高
さｈを算出して、この高さｈに依存する１画素当たりの
走行距離ｆを求め、 Ｓ＝ｎ×ｆ／ｔ により車両の走行速度Ｓを算出している。Further, in the vehicle speed measuring method according to the present invention, a vehicle that has entered a predetermined point within the imaging range of the camera is sensed by the sensor, and a first image is captured by the camera when the sensor senses the vehicle. By extracting feature points common to the first image and the second image captured by the camera after time t,
The addresses of the feature points in both images are obtained, the number n of moving pixels of the vehicle is calculated from the difference between the addresses of the feature points in each image, and the height h of the feature points is calculated from the address m of the feature points in the first image. Then, the traveling distance f per pixel depending on the height h is calculated, and the traveling speed S of the vehicle is calculated by S = n × f / t.
【０００８】そのため、車両のナンバープレートの取り
付け高さが異なっても、車両速度を正確に求めることが
できる。[0008] Therefore, even if the mounting height of the license plate of the vehicle is different, the vehicle speed can be accurately obtained.
【０００９】[0009]
【発明の実施の形態】実施形態のナンバープレート自動
認識装置は、図２に示すように、道路上に設置された、
車両を感知する感知器１と、車両を前方から撮影するカ
メラ２とを備えている。BEST MODE FOR CARRYING OUT THE INVENTION A license plate automatic recognition device according to an embodiment is installed on a road as shown in FIG.
The vehicle includes a sensor 1 for detecting a vehicle, and a camera 2 for photographing the vehicle from the front.
【００１０】ナンバープレート自動認識装置自体のブロ
ック構成としては、図１に示すように、感知器１及びカ
メラ２の他に、カメラの画像信号をデジタルデータに変
換するＡ／Ｄ変換部３と、撮影時間が異なる２枚の画像
データを格納する画像メモリ４ａ、４ｂと、画像から特
徴点を抽出する特徴抽出部５と、ナンバープレートの文
字を認識する文字認識部６と、２枚の画像データから車
両速度を計測する速度計測部７とを備えている。As shown in FIG. 1, in addition to the sensor 1 and the camera 2, an A / D converter 3 for converting an image signal of the camera into digital data, as shown in FIG. Image memories 4a and 4b for storing two pieces of image data having different photographing times, a feature extracting unit 5 for extracting feature points from images, a character recognizing unit 6 for recognizing characters on a license plate, and two pieces of image data And a speed measuring unit 7 for measuring a vehicle speed from the vehicle.
【００１１】このナンバープレート自動認識装置では、
路上に設置された感知器１が車両Ａの先頭を感知する
と、感知器１の感知地点を撮像範囲に含むように設置さ
れたカメラ２が、車両Ａの前面を撮像し、次いで、一定
時間（ｔ時間）の間隔を空けて２枚目の画像を撮像す
る。このカメラ２が撮像した画像情報（アナログ量）
は、Ａ／Ｄ変換器３でデジタルデータに変換され、１枚
目の画像データが第１の画像メモリ４ａに、また、２枚
目の画像情報が第２の画像メモリ４ｂに記録される。特
徴抽出部５は、各画像メモリ４ａ、４ｂに記録された静
止画像から特徴を抽出し、文字認識部６は、特徴抽出部
５の処理を基に文字認識を実行してナンバーを読み取
る。速度計測部７は、２枚の画像に映る車両位置の差か
ら車両速度を計測する。In this automatic license plate recognition device,
When the sensor 1 installed on the road senses the head of the vehicle A, the camera 2 installed so as to include the sensing point of the sensor 1 in the imaging range captures an image of the front of the vehicle A, and then for a certain time ( The second image is captured at intervals of (t time). Image information (analog amount) captured by this camera 2
Are converted into digital data by the A / D converter 3, and the first image data is recorded in the first image memory 4a, and the second image information is recorded in the second image memory 4b. The feature extracting unit 5 extracts features from the still images recorded in the image memories 4a and 4b, and the character recognizing unit 6 executes character recognition based on the processing of the feature extracting unit 5 to read the number. The speed measurement unit 7 measures the vehicle speed from the difference between the vehicle positions shown in the two images.
【００１２】このカメラ２は、図２で示すように、車両
Ａの前部が感知器１で感知された瞬間に１枚目の画像を
撮像し、この後、一定時間（ｔ時間）経過後（速度Ｓで
走行する車両Ａが撮像範囲を逸脱しない時間ｔ後）に、
２枚目の画像を撮像する。As shown in FIG. 2, the camera 2 captures the first image at the moment when the front part of the vehicle A is detected by the sensor 1, and thereafter, after a lapse of a predetermined time (t time). (After time t when vehicle A traveling at speed S does not deviate from the imaging range)
The second image is captured.
【００１３】特徴抽出部５は、各画像メモリ４ａ、４ｂ
が記憶する静止画像に対し、図３（Ａ）、（Ｂ）に示す
ように、ナンバープレートＢの検出、文字切り出し等、
文字認識を行うための処理を実行するとともに、２枚の
静止画像における同一の特徴点Ｐａ、Ｐｂを抽出し、そ
のアドレスを求める。The feature extraction unit 5 includes image memories 4a, 4b
As shown in FIGS. 3A and 3B, for the still image stored by, the detection of the license plate B, the character cutout, etc.
A process for performing character recognition is executed, and the same feature points Pa and Pb in two still images are extracted and their addresses are obtained.
【００１４】ここでは、ナンバープレートＢの文字の中
央線を特徴点としている。この特徴点は、これに限ら
ず、たとえば車両Ａのバンパー下部でも良いし、ヘッド
ライトであっても良い。ただ、ナンバープレートＢの文
字を特徴点とした場合には、車両Ａのバンパー下部等と
比較して、その点を容易に断定でき、正確にアドレスを
求める事ができ、速度計測の精度を上げることができ
る。Here, the center line of the character on the license plate B is a feature point. This feature point is not limited to this, and may be, for example, a lower portion of the bumper of the vehicle A or a headlight. However, when the character of the license plate B is used as a feature point, the point can be easily determined as compared with the lower part of the bumper of the vehicle A, the address can be obtained accurately, and the speed measurement accuracy is improved. be able to.
【００１５】速度計測部７は、図３（Ａ）及び（Ｂ）で
示すように、第１及び第２の静止画像における特徴点Ｐ
ａ、Ｐｂのアドレスから、特徴点の移動画素数ｎを求
め、車両の走行速度Ｓを次式（１）によって算出する。As shown in FIGS. 3 (A) and 3 (B), the speed measuring section 7 calculates the characteristic points P in the first and second still images.
From the addresses a and Pb, the number n of moving pixels of the feature point is obtained, and the traveling speed S of the vehicle is calculated by the following equation (1).
【００１６】 Ｓ＝（ｆ×ｎ）／ｔ （１） ここで、２枚の画像の撮影間隔を示すｔは、ビデオカメ
ラを用いる場合、フレーム間隔であり、一般的には３３
ｍｓである。また、ｆは１画素当たりの走行距離を示し
ている。このｆは、特徴点の地上からの高さｈによって
変化する。このｈは、１枚目の画像の特徴点のＰａのア
ドレス（ｍ画素）から、次式（２）によって求めること
ができる。S = (f × n) / t (1) Here, t indicating a shooting interval between two images is a frame interval when a video camera is used, and generally 33.
ms. In addition, f indicates a traveling distance per pixel. This f varies depending on the height h of the feature point from the ground. This h can be obtained by the following equation (2) from the Pa address (m pixels) of the feature point of the first image.
【００１７】 ｈ＝ｐ×ｍ （２） ここで、ｐは１画素当たりの高さを示す値である。H = p × m (2) Here, p is a value indicating the height per pixel.
【００１８】この走行速度Ｓを求める詳しい計算の説明
は後述することにして、その手順について、図４のフロ
ー図で説明する。The detailed calculation for calculating the traveling speed S will be described later, and the procedure will be described with reference to the flowchart of FIG.
【００１９】ステップ１：路上を走行する車両Ａがカメ
ラ２の撮像範囲に入り、感知器１が感知すると、 ステップ２：カメラ１は、その瞬間に１枚目の画像を撮
像し、図３（Ａ）で示す静止画像が第１の画像メモリ４
ａに記録される。Step 1: When the vehicle A running on the road enters the imaging range of the camera 2 and the sensor 1 senses, Step 2: the camera 1 captures the first image at that moment, and FIG. The still image shown in A) is stored in the first image memory 4.
recorded in a.
【００２０】ステップ３：ｔ時間経過後に、 ステップ４：カメラ１は２枚目の画像を撮像し、図３
（Ｂ）で示す静止画像が第２の画像メモリ４ｂに記録さ
れる。Step 3: After a lapse of t time, Step 4: the camera 1 captures a second image, and FIG.
The still image shown in (B) is recorded in the second image memory 4b.
【００２１】ステップ５：特徴抽出部５は、各静止画像
に対し、ナンバープレートＢの検出、文字切り出し等、
文字認識を行うための処理を行う。この処理過程で、各
静止画像の特徴点Ｐａ、Ｐｂを抽出し、 ステップ６：そのアドレスを求める。Step 5: The feature extracting unit 5 detects license plate B, cuts out characters, etc. for each still image.
Perform processing for character recognition. In this process, feature points Pa and Pb of each still image are extracted. Step 6: The addresses are obtained.
【００２２】この後、文字認識部６では、特徴抽出部５
で行われた処理に基づき、ナンバープレートＢの文字認
識を実行する。一方、速度計測部７では、 ステップ７：特徴抽出部５で求められた特徴点Ｐａ、Ｐ
ｂのアドレスから特徴点の移動画素数ｎを算出し、 ステップ８：また、１枚目の画像の特徴点Ｐａのアドレ
スから、特徴点Ｐａの地面からの高さを算出し、 ステップ９：特徴点の地面からの高さと、カメラ１の視
野角、設置高さ、俯角等から求めた１画素あたりの走行
距離ｆを用いて、式（１）により、車両Ａの走行速度Ｓ
を算出する。Thereafter, the character recognizing section 6 includes a feature extracting section 5
The character recognition of the license plate B is executed based on the processing performed in step (1). On the other hand, in the speed measurement unit 7, Step 7: the feature points Pa and P obtained by the feature extraction unit 5
Step 8: Calculate the height n of the feature point Pa from the ground from the address of the feature point Pa of the first image, and calculate the number n of the moving pixels of the feature point from the address b. Using the height of the point from the ground and the travel distance f per pixel obtained from the viewing angle, installation height, depression angle, etc. of the camera 1, the traveling speed S of the vehicle A is calculated by Expression (1).
Is calculated.
【００２３】図５は、特徴点の１画素当たり高さｐの求
め方を説明している。FIG. 5 explains how to determine the height p per pixel of a feature point.
【００２４】ここでは、カメラの俯角をθ、１／２視野
角をφ、カメラの高さをＴ、カメラから感知器までの距
離をｄとしている。ここで、高さ方向をｙ、距離方向を
ｘで表すと、カメラの上側の視野境界を示す線Ａは、 ｙ＝−ｔａｎ（θ−φ）ｘ＋Ｔ と表すことができ、カメラの下側の視野境界を示す線Ｂ
は、 ｙ＝−ｔａｎ（θ＋φ）ｘ＋Ｔ となる。この線Ａが感知器からの垂線と交わる高さを
ｋ、線Ｂが感知器からの垂線と交わる高さをｌとする
と、 ｋ＝−ｔａｎ（θ−φ）ｄ＋Ｔ ｌ＝−ｔａｎ（θ＋φ）ｄ＋Ｔ となる。ここで、感知器の真下の基点０上の点を通り、
カメラの中心線と直交する線Ｃを考える。線Ｃの基点０
から線Ａまでの距離をａ、線Ｃの基点０から線Ｂまでの
距離をｂとするとき、ａ、ｂは次のように表せる。 ａ＝ｋ｛ｓｉｎ（９０°−θ＋φ）／ｓｉｎ（９０°−
φ）｝ ｂ＝ｌ｛ｓｉｎ（９０°−θ−φ）／ｓｉｎ（９０°−
φ）｝Here, the depression angle of the camera is θ, the half viewing angle is φ, the height of the camera is T, and the distance from the camera to the detector is d. Here, if the height direction is represented by y and the distance direction is represented by x, a line A indicating the upper visual field boundary of the camera can be represented by y = −tan (θ−φ) x + T, Line B indicating visual field boundary
Becomes y = −tan (θ + φ) x + T. Assuming that the height at which the line A intersects with the perpendicular from the sensor is k and the height at which the line B intersects with the perpendicular from the sensor is l, k = -tan (θ-φ) d + T l = -tan (θ + φ) d + T. Here, pass through the point on the base point 0 just below the sensor,
Consider a line C perpendicular to the center line of the camera. Base point 0 of line C
Let a be the distance from the line A to the line A and b be the distance from the base point 0 of the line C to the line B, a and b can be expressed as follows. a = k ｛sin (90 ° −θ + φ) / sin (90 ° −
φ)｝ b = l ｛sin (90 ° −θ−φ) / sin (90 ° −
φ)｝
【００２５】カメラの撮像できる縦の画素数は固定（Ｖ
とする）である。そして、ａ＋ｂの長さでＶの画素があ
ることになる。そのため、長さａの画素数を算出する
と、 長さａの画素数＝Ｖ×ａ／（ａ＋ｂ） となる。カメラの長さａの画素数で、高さｋを撮像する
ので、１画素当たりの高さｐは、 ｐ＝ｋ（ａ＋ｂ）／ａＶ ＝［｛−ｔａｎ（θ−φ）ｄ＋Ｔ｝ｓｉｎ（９０°−θ＋φ） ＋｛−ｔａｎ（θ＋φ）ｄ＋Ｔ｝ｓｉｎ（９０°−θ−φ）］／ Ｖ・ｓｉｎ（９０°−θ−φ） （３） となる。この式（３）のｐを用いて、式（２）により、
特徴点の高さを算出することができる。The number of vertical pixels that can be picked up by the camera is fixed (V
). Then, there is a pixel of V having a length of a + b. Therefore, when the number of pixels of the length a is calculated, the number of pixels of the length a = V × a / (a + b). Since the height k is imaged by the number of pixels of the camera length a, the height p per pixel is: p = k (a + b) / aV = [｛-tan (θ-φ) d + T｝ sin (90 ° −θ + φ) + ｛− tan (θ + φ) d + T｝ sin (90 ° −θ−φ)] / V · sin (90 ° −θ−φ) (3) Using p of this equation (3), according to equation (2),
The height of the feature point can be calculated.
【００２６】次に、図６は、１画素当たりの走行距離ｆ
の求め方を説明している。Next, FIG. 6 shows a running distance f per pixel.
Explains how to ask.
【００２７】の軌跡の高さをｈとすると、線Ａとｙ＝
ｈとが交わる点Ｘａ及び線Ｂとｙ＝ｈとが交わる点Ｘｂ
は、 Ｘａ＝（Ｔ−ｈ）／ｔａｎ（θ−φ） Ｘｂ＝（Ｔ−ｈ）／ｔａｎ（θ＋φ） となる。α＝Ｘａ−Ｘｂとすると、 α＝｛（Ｔ−ｈ）／ｔａｎ（θ−φ）｝ −｛（Ｔ−ｈ）／ｔａｎ（θ＋φ）｝ （４） となる。この式（４）から明らかなように、αはｈの関
数である。Assuming that the height of the locus of h is h, the line A and y =
a point Xa where h intersects and a point Xb where line B intersects y = h
Xa = (Th) / tan (θ-φ) Xb = (Th) / tan (θ + φ) If α = Xa−Xb, α = {(Th) / tan (θ−φ)} − {(Th) / tan (θ + φ)} (4) As is apparent from the equation (4), α is a function of h.
【００２８】この距離αは撮像画面の縦の画素数（Ｖ）
に匹敵するので、１画素当たりの走行距離ｆは、 ｆ＝α／Ｖ （５） となる。This distance α is the number of vertical pixels (V) of the image pickup screen.
Therefore, the traveling distance f per pixel is f = α / V (5)
【００２９】従って、（１）（２）（３）（４）（５）
から、走行速度Ｓを正確に求めることが可能になる。Therefore, (1) (2) (3) (4) (5)
From this, it becomes possible to accurately determine the traveling speed S.
【００３０】このように、この実施形態のナンバープレ
ート自動認識装置では、車両のナンバープレートの取り
付け位置に関わらず、車両速度を正確に計測することが
できる。As described above, the automatic license plate recognition apparatus of this embodiment can accurately measure the vehicle speed regardless of the position where the license plate is mounted on the vehicle.
【００３１】[0031]
【発明の効果】以上の説明から明らかなように、本発明
のナンバープレート自動認識装置及び車両測定方法で
は、一定時間の移動距離から速度を計測する方式におい
て、１画素当たりの走行距離を厳密に求めているため、
高精度の速度計測を実現することができる。As is apparent from the above description, in the automatic license plate recognition apparatus and the vehicle measuring method of the present invention, the traveling distance per pixel is strictly measured in the method of measuring the speed from the moving distance for a certain time. Because we are seeking
Highly accurate speed measurement can be realized.
【００３２】従って、ナンバープレート自動認識装置に
は、速度センサを別に設ける必要が無く、スペースやコ
ストの削減を図ることができる。Therefore, it is not necessary to separately provide a speed sensor in the automatic license plate recognition device, and it is possible to reduce the space and cost.
【図１】本発明の実施形態におけるナンバープレート自
動認識装置の構成を示すブロック図、FIG. 1 is a block diagram showing a configuration of a license plate automatic recognition device according to an embodiment of the present invention;
【図２】本発明の実施形態におけるナンバープレート自
動認識装置の配置図、FIG. 2 is a layout view of a license plate automatic recognition device according to the embodiment of the present invention;
【図３】本発明の実施形態におけるナンバープレート認
識装置により撮像された１枚目の画像（Ａ）と、２枚目
の画像（Ｂ）を示す図、FIG. 3 is a diagram showing a first image (A) and a second image (B) captured by the license plate recognition device according to the embodiment of the present invention;
【図４】本発明の実施形態におけるナンバープレート自
動認識装置の動作を示すフローチャート、FIG. 4 is a flowchart showing an operation of the automatic license plate recognition apparatus according to the embodiment of the present invention;
【図５】実施形態のナンバープレート認識装置での特徴
点の高さの算出方法を説明する説明図、FIG. 5 is an explanatory diagram illustrating a method for calculating the height of a feature point in the license plate recognition device according to the embodiment;
【図６】実施形態のナンバープレート認識装置での１画
素当たりの走行距離の算出方法を説明する説明図、FIG. 6 is an explanatory diagram illustrating a method of calculating a traveling distance per pixel in the license plate recognition device according to the embodiment;
１ 感知器 ２ カメラ ３ Ａ／Ｄ変換部 ４ａ、４ｂ 画像メモリ ５ 特徴抽出部 ６ 文字認識部 ７ 速度計測部 DESCRIPTION OF SYMBOLS 1 Sensor 2 Camera 3 A / D conversion part 4a, 4b Image memory 5 Feature extraction part 6 Character recognition part 7 Speed measurement part
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｇ０６Ｔ 7/00 Ｇ０６Ｆ 15/70 ４６０Ｂ Ｆターム(参考） 2F065 AA06 AA09 AA11 BB05 BB28 CC11 DD02 DD03 FF04 FF26 FF34 GG09 JJ03 JJ26 KK02 MM03 PP01 QQ03 QQ24 QQ26 QQ27 UU03 UU05 UU09 2F112 AD05 BA06 BA09 BA20 CA05 FA03 FA07 FA19 FA39 5H180 AA01 CC04 DD07 DD10 5L096 BA04 CA02 FA44 FA51 FA64 HA04 9A001 HZ23 JJ77 KK37 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) G06T 7/00 G06F 15/70 460B F term (Reference) 2F065 AA06 AA09 AA11 BB05 BB28 CC11 DD02 DD03 FF04 FF26 FF34 GG09 JJ03 JJ26 KK02 MM03 PP01 QQ03 QQ24 QQ26 QQ27 UU03 UU05 UU09 2F112 AD05 BA06 BA09 BA20 CA05 FA03 FA07 FA19 FA39 5H180 AA01 CC04 DD07 DD10 5L096 BA04 CA02 FA44 FA51 FA64 HA04 9A001 HZ23 JJ77 KK37
Claims (2)
メラを備え、撮影画像からナンバープレートの文字認識
と車両速度の測定とを行うナンバープレート自動認識装
置において、 前記カメラの撮像範囲内の所定地点に進入した車両を感
知する感知手段と、 前記感知手段が感知した時点で前記カメラにより撮像さ
れた１枚目の画像を記憶する第１の画像メモリと、 前記カメラが撮像した２枚目の画像を記憶する第２の画
像メモリと、 前記各画像メモリに記録された画像から共通する特徴点
を抽出し、そのアドレスを求める特徴抽出手段と、 各画像の前記特徴点のアドレスの差分から車両の移動画
素数を算出し、１枚目の画像の特徴点のアドレスから特
徴点の高さを算出し、それを基に１画素当たりの走行距
離を算出して、車両の走行速度を求める速度計測手段と
を備えることを特徴とするナンバープレート自動認識装
置。1. A license plate automatic recognition device comprising: a camera that images a traveling vehicle at a set depression angle; and performs character recognition of a license plate and measurement of a vehicle speed from a captured image. Sensing means for sensing a vehicle that has entered a point; a first image memory for storing a first image taken by the camera at the time of sensing by the sensing means; a second image taken by the camera A second image memory for storing images, a feature extracting means for extracting a common feature point from the images recorded in each of the image memories and obtaining an address thereof, and a vehicle based on a difference between addresses of the feature points of each image. , The height of the feature point is calculated from the address of the feature point of the first image, and the travel distance per pixel is calculated based on the calculated height. Automatic license plate recognition system, characterized in that it comprises a Mel speed measuring means.
を撮像し、その撮影画像から車両速度を測定する車両速
度測定方法において、 前記カメラの撮像範囲内の所定地点に進入した車両を感
知手段で感知し、 前記感知手段が感知した時点で前記カメラにより１枚目
の画像を撮像し、前記１枚目の画像と前記カメラがｔ時
間後に撮像した２枚目の画像とに共通する特徴点を抽出
して、両方の画像における前記特徴点のアドレスを求
め、 各画像の特徴点のアドレスの差分から車両の移動画素数
ｎを算出し、１枚目の画像の特徴点のアドレスｍから前
記特徴点の高さｈを算出して、前記高さｈに依存する１
画素当たりの走行距離ｆを求め、 Ｓ＝ｎ×ｆ／ｔ により車両の走行速度Ｓを算出することを特徴とする車
両速度測定方法。2. A vehicle speed measuring method for capturing an image of a running vehicle with a camera set at a predetermined depression angle and measuring a vehicle speed from the captured image, wherein a vehicle entering a predetermined point within an imaging range of the camera is detected. The first image is taken by the camera at the time when the sensing means senses, and the feature points common to the first image and the second image taken by the camera after t hours. To obtain the addresses of the feature points in both images, calculate the number n of moving pixels of the vehicle from the difference between the addresses of the feature points in each image, and calculate the The height h of the feature point is calculated, and 1 depending on the height h is calculated.
A vehicle speed measuring method, wherein a running distance f per pixel is obtained, and a running speed S of the vehicle is calculated by S = n × f / t.
Priority Applications (1)
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|---|---|---|---|
| JP30947799A JP2001126184A (en) | 1999-10-29 | 1999-10-29 | Automatic license plate recognizing device and vehicle speed measuring method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30947799A JP2001126184A (en) | 1999-10-29 | 1999-10-29 | Automatic license plate recognizing device and vehicle speed measuring method |
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| Publication Number | Publication Date |
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| JP2001126184A true JP2001126184A (en) | 2001-05-11 |
Family
ID=17993464
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| JP30947799A Withdrawn JP2001126184A (en) | 1999-10-29 | 1999-10-29 | Automatic license plate recognizing device and vehicle speed measuring method |
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