SINGLE-CAMERA SYSTEM FOR MEASURING A VEHICLE DISTANCE AND MEASUREMENT METHOD THEREOF

• US 20160320184A1
• Filed: 10/17/2015
• Published: 11/03/2016
• Est. Priority Date: 04/29/2015
• Status: Active Grant

• Current Assignee: Protruly Vision Technology Group Company Limited
• Original Assignee: Protruly Vision Technology Group Company Limited
• Inventors: Long, Gang, Lin, Songwei
• Granted Patent: US 9,964,406 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 2207/30261 Obstacle
• CPC Class Codes: G06T 7/50 Depth or shape recovery
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

The present invention discloses a single-camera system for measuring a vehicle distance and measurement method thereof. The single-camera system for measuring the vehicle distance comprises a variable-magnification single-camera module, an operational control module and an infrared emission module, wherein the operational control module is respectively connected with the variable-magnification single-camera module and the infrared emission module. The variable-magnification single-camera module is used for performing real-time video recording on a front scene, capturing the position information of a highlight speckle in a video image from a video and capturing the number of pixels occupied by the width/height of a vehicle license plate. The operational control module is used for obtaining the position information of the highlight speckle outputted by the variable-magnification single-camera module and the number of the pixels occupied by the width/height of the vehicle license plate, and computing a vehicle distance according to a geometrical relationship and an averaging algorithm. The present invention combines the video processing technology with the infrared control technology of a camera, enhances the measuring reliability of short distance of a vehicle, facilitates the usage, reduces the cost and can be widely applied to an active safety assisting system of the vehicle

Claims

1. A single-camera system for measuring a vehicle distance, comprising a variable-magnification single-camera module (2), an operational control module (3) and an infrared emission module (4), characterized in that said operational control module (3) is respectively connected with the variable-magnification single-camera module (2) and the infrared emission module (4);

said variable-magnification single-camera module (2) is used for performing real-time video recording on a front scene, capturing the position information of a highlight speckle in a video image from a video and capturing the number of pixels occupied by the width height of a vehicle license plate(6);

said operational control module (3) is used for obtaining the position information of the highlight speckle outputted by the variable-magnification single-camera module (2) and the number of the pixels occupied by the width/height of the vehicle license plate (6), and computing a vehicle distance according to a geometrical relationship and an averaging algorithm; and

said infrared emission module (4) is used for receiving a control command of the operational control module (3) to enable and emit an infrared light beam and close the infrared light beam.

2. The single-camera system for measuring the vehicle distance according to claim 1, characterized in that the magnification change mode of said variable-magnification single-camera module (2) is optical magnification change or/and digital magnification change.

3. A measurement method of the single-camera system for measuring the vehicle distance of any of claims 1, characterized by comprising the specific steps as follows:

1) In a static state, measuring the lengths L of the width/height S of the vehicle license plate (6) mapped to a video image in advance when a front vehicle body (5) is placed in different vehicle distances when the camera is in A magnification, and forming a group of static data (AL1, AL2, AL3, . . . ALn) according to different vehicle distances;

measuring a second group of static data {BL1, BL2, BL3, . . . BLn} formed when the camera is in B magnification according to the method;

obtaining all data from 1 magnification to M magnification according to the method; and

thus, forming 1 to M group of static data, wherein each group is a data table of data volume of 1 to M;

2) storing static tables formed by the static data in the above-mentioned step in the operational control module (3);

3) controlling the variable-magnification single-camera module (2) by the operational control module (3) to pull the magnification of the camera to a certain magnification, and obtaining the pixel width/height value of the vehicle license plate (6) mapped to the video image at this moment by the variable-magnification single-camera module (2);

4) obtaining by the operational control module (3) the above-mentioned pixel width/height value mapped by the vehicle license plate (6), computing the actual width/height of the vehicle license plate (6) in the video image according to the actual width/height occupied by each pixel, and obtaining first vehicle distance data D1 through the method of searching the static data table according to the actual width/height value of the vehicle license plate (6);

5) notifying the infrared emission module (4) by the operational control module (3) to start to work, and emitting a light beam onto the front vehicle body (5) by the infrared emission module (4);

6) the variable-magnification single-camera module (2) starts to work for capturing an infrared bright spot mapped to the video and obtaining a perpendicular pixel value from the infrared bright spot to a light axis of the camera;

7) obtaining the actual width/height occupied by the above-mentioned perpendicular pixel value and each pixel value in the image by the operational control module (3), computing the actual distance S from the infrared bright spot to the light axis, obtaining a video focal distance W of the current camera by the operational control module (3), computing the value of an angle θ

, tan θ

=S/W, and computing second vehicle distance data D2, D2=H/tan θ

according to predetermined position height H, wherein H is the distance from a video recording light axis to an infrared emission light axis;

8) performing weighted average on the first vehicle distance data D1 obtained in step

     4) and the second vehicle distance data D2 obtained in step

     7) to obtain final vehicle distance data D, and performing compensation by the first vehicle distance data D1 obtained in step

     4) or directly using the first vehicle distance data D1 obtained in step

     4) as the final vehicle distance data D when the highlight speckle caused by the infrared light beam emitted by the infrared emission module (4) is not obvious and cannot be captured by the camera.

4. A measurement method of the single-camera system for measuring the vehicle distance of any of claims 2, characterized by comprising the specific steps as follows:

1) In a static state, measuring the lengths L of the width/height S of the vehicle license plate (6) mapped to a video image in advance when a front vehicle body (5) is placed in different vehicle distances when the camera is in A magnification, and forming a group of static data (AL1, AL2, . . . ALn} according to different vehicle distances;

measuring a second group of static data {BL1, BL2, BL3 . . . BLn} formed when the camera is in B magnification according to the method;

obtaining all data from 1 magnification to M magnification according to the method; and

thus, forming 1 to M group of static data, wherein each group is a data table of data volume of 1 to M;

2) storing static tables formed by the static data in the above-mentioned step in the operational control module (3);

3) controlling the variable-magnification single-camera module (2) by the operational control module (3) to pull the magnification of the camera to a certain magnification, and obtaining the pixel width/height value of the vehicle license plate (6) mapped to the video image at this moment by the variable-magnification single-camera module (2);

4) obtaining by the operational control module (3) the above-mentioned pixel width/height value mapped by the vehicle license plate (6), computing the actual width/height of the vehicle license plate (6) in the video image according to the actual width/height occupied by each pixel, and obtaining first vehicle distance data D1 through the method of searching the static data table according to the actual width/height value of the vehicle license plate (6);

5) notifying the infrared emission module (4) by the operational control mod tie (3) to start to work, and emitting a light beam onto the front vehicle body (5) by the infrared emission module (4);

6) the variable-magnification single-camera module (2) starts to work for capturing an infrared bright spot mapped to the video and obtaining a perpendicular pixel value from the infrared bright spot to a light axis of the camera;

7) obtaining the actual width/height occupied by the above-mentioned perpendicular pixel value and each pixel value in the image by the operational control module (3), computing the actual distance S from the infrared bright spot to the light axis, obtaining a video focal distance W of the current camera by the operational control module (3), computing the value of an angle θ

, tan θ

=S/W, and computing second vehicle distance data D2, D2=H/tan θ

according to predetermined position height H, wherein H is the distance from a video recording light axis to an infrared emission light axis;

8) performing weighted average on the first vehicle distance data D1 obtained in step

     4) and the second vehicle distance data D2 obtained in step

     7) to obtain final vehicle distance data D, and performing compensation by the first vehicle distance data D1 obtained in step

     4) or directly using the first vehicle distance data D1 obtained in step

     4) as the final vehicle distance data D when the highlight speckle caused by the infrared light beam emitted by the infrared emission module (4) is not obvious and cannot be captured by the camera.