A method to improve vehicle surround view calibration accuracy

Abstract

The invention discloses a method for improving the accuracy of vehicle surround view calibration, comprising the following steps: S1, selecting a point as a reference point on a calibration station for vehicle surround view calibration, and placing a height gauge at the reference point; S2, setting a plurality of measuring points on a target block as a target object, placing a laser leveler at different measuring points of each target block, rotating the laser leveler so that a horizontal laser line hits the height gauge, and then reading the height gauge; S3, calculating the difference between the height gauge reading corresponding to each measuring point and the theoretical height of the target block to obtain the height error of the measuring point, summing the height errors corresponding to all measuring points on the same target block and dividing the sum by the number of measuring points on the target block to obtain the average height error of the target block; S4, substituting the height errors of the measuring points of all target blocks and the average height error of the target blocks into an image stitching algorithm for correction, so as to improve the accuracy of surround view calibration.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle surround view calibration, and particularly relates to a method for improving the accuracy of vehicle surround view calibration. Background Art

[0002] The 360-degree surround view system can greatly expand the driver's perception of the surroundings and environment, allowing the driver to handle vehicle starting, driving, turning, parking, avoiding obstacles, etc. calmly and easily. It can effectively reduce the occurrence of scratches and even collisions and crushing accidents, and is therefore widely used in the passenger car field.

[0003] Due to factors such as camera manufacturing and assembly errors and camera bracket mold errors, the surround view system may experience stitching misalignment after leaving the factory. Therefore, the imaging results of the surround view system need to be calibrated (each camera is calibrated to generate its distortion correction and perspective transformation parameters, as well as the stitching parameters of the bird's-eye view, and the deviation between them and the default parameters within the system is corrected to ensure that images from all directions can be correctly stitched together to form a panoramic image).

[0004] During surround view system calibration, the target block must be imaged and then stitched together. The target block is typically assumed to be perfectly flat (all regions are at the same height), and the stitching algorithm uses theoretical height values. However, the error between the theoretical and actual height values ​​of each region on the target block is related to the misalignment of the images in the stitched area. Therefore, reducing the impact of target block flatness errors can improve calibration accuracy and enhance the stitching performance of the surround view system. Summary of the Invention

[0005] The object of the present invention is to provide a method for improving the calibration accuracy of a vehicle surround view system, so as to reduce the negative impact of the flatness error of the calibration object on the stitching effect of the surround view system.

[0006] To solve the above technical problems, the present invention provides a technical solution: a method for improving the accuracy of vehicle surround view calibration, comprising the following steps:

[0007] S1. Select a point on the calibration station used for vehicle surround view calibration as a reference point and place a height gauge at the reference point;

[0008] S2. Set several measuring points on the target block as the target object, place the laser leveler at different measuring points on each target block, rotate the laser leveler so that the horizontal laser line hits the height gauge, and then read the height gauge reading;

[0009] S3. Subtract the height gauge reading corresponding to each measuring point from the theoretical height of the target block to obtain the height error of the measuring point. Sum the height errors corresponding to all measuring points on the same target block and divide the sum by the number of measuring points on the target block to obtain the average height error of the target block.

[0010] S4. Substitute the height errors of each measurement point of all target blocks and the average height error of the target blocks into the image stitching algorithm for correction to improve the surround calibration accuracy.

[0011] According to the above scheme, the number of measurement points set on the target block is 8, which are located at the four vertices and the midpoints of the four sides of the square target block.

[0012] A device for improving vehicle surround view calibration accuracy for implementing the above-mentioned method for improving vehicle surround view calibration accuracy comprises:

[0013] Calibration station, used to park vehicles to be calibrated;

[0014] The vehicle to be calibrated is provided with a plurality of cameras located around the vehicle;

[0015] A plurality of calibration blocks are arranged on the calibration station, arranged around the vehicle parking area, and symmetrically distributed along the horizontal and vertical center axes of the calibration station;

[0016] Several target blocks are set at the center of the calibration block, and the upper surface of the target block has the same theoretical height as the calibration block;

[0017] Height gauge, placed at the reference point selected on the calibration station;

[0018] Laser leveling device is used to obtain the height of each measuring point on the target block relative to the reference point.

[0019] According to the above scheme, the number of cameras installed on the vehicle to be calibrated is 4, which are located on the front, rear, left and right sides of the vehicle respectively.

[0020] According to the above scheme, the number of calibration blocks is 4, which are respectively set at the four top corners of the calibration station.

[0021] The beneficial effect of the present invention is that the relative height of each measuring point on the target object is obtained by using a laser leveler and a height ruler, and then the unevenness of the target block is obtained, so that the image stitching algorithm can be corrected accordingly, thereby improving the accuracy of the surround calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A top view of a device for improving vehicle surround view calibration accuracy according to an embodiment of the present invention;

[0023] Figure 2A side sectional view of a calibration block according to an embodiment of the present invention;

[0024] Figure 3 A distribution diagram of measurement points on a target block according to an embodiment of the present invention;

[0025] Figure 4 FIG. 1 is a schematic diagram of height measurement using a laser leveling device according to an embodiment of the present invention.

[0026] In the figure: 1-calibration station, 2-calibration block, 3-target block, 4-vehicle, 401-left camera, 402-front camera, 403-right camera, 404-rear camera, 5-reference point, 6-height gauge, 7-laser leveler, 701-laser line, 702-laser leveler rotation axis. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0028] See also Figures 1 to 4 ,A method for improving the calibration accuracy of vehicle surround view, comprising the following steps,

[0029] S1. Select a point on the calibration station 1 for performing surround view calibration of the vehicle 4 as the reference point 5, and place a height gauge 6 at the reference point 5;

[0030] S2. Set several measuring points on the target block 3 as the target object, place the laser leveler 7 at different measuring points on each target block 3, rotate the laser leveler 7 around the laser leveler rotation axis 702 so that the horizontal laser line 701 hits the height gauge 6, and then read the height gauge reading;

[0031] S3, the height error of the measuring point is obtained by subtracting the height gauge reading corresponding to each measuring point from the theoretical height of the target block 3, and the height errors corresponding to all measuring points on the same target block 3 are summed and divided by the number of measuring points on the target block 3 to obtain the average height error of the target block 3;

[0032] S4. Substitute the height errors of all measurement points of all target blocks 3 and the average height error of the target block 3 into the image stitching algorithm for correction to improve the surround calibration accuracy.

[0033] Furthermore, the number of measurement points set on the target block 3 is 8, which are respectively located at the four vertices and the midpoints of the four sides of the square target block 3 .

[0034] The height error of each target block 3 is shown in the table below, where H0 is the theoretical height of the target block

[0035]

[0036] Calculation of the average height error of each target block 3:

[0037]

[0038] A device for improving vehicle surround view calibration accuracy for implementing the above-mentioned method for improving vehicle surround view calibration accuracy comprises:

[0039] Calibration station 1, used for parking the vehicle 4 to be calibrated;

[0040] A vehicle 4 to be calibrated is provided with a plurality of cameras located around the vehicle 4;

[0041] A plurality of calibration blocks 2 are provided on the calibration station 1, are provided around the parking area of ​​the vehicle 4, and are symmetrically distributed along the horizontal and vertical center axes of the calibration station 1;

[0042] Several target blocks 3 are arranged at the center of the calibration block 2, and the upper surface of the target block 3 has the same theoretical height as the calibration block 2;

[0043] The height gauge 6 is placed at the reference point 5 selected on the calibration station 1;

[0044] The laser leveler 7 is used to obtain the height of each measuring point on the target block 3 relative to the reference point 5.

[0045] Furthermore, the number of cameras installed on the vehicle 4 to be calibrated is 4, which are located on the front, rear, left and right sides of the vehicle, namely the front camera 402, rear camera 404, left camera 401 and right camera 403 in the figure.

[0046] Furthermore, there are four calibration blocks 2 , which are respectively arranged at the four top corners of the calibration station 1 .

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for improving vehicle surround view calibration accuracy, characterized by: The following steps are included: S1. Select a point on the calibration station used for vehicle surround view calibration as a reference point and place a height gauge at the reference point; S2. Set several measuring points on the target block as the target object, place the laser leveler at different measuring points on each target block, rotate the laser leveler so that the horizontal laser line hits the height gauge, and then read the height gauge reading; S3. Subtract the height gauge reading corresponding to each measuring point from the theoretical height of the target block to obtain the height error of the measuring point. Sum the height errors corresponding to all measuring points on the same target block and divide the sum by the number of measuring points on the target block to obtain the average height error of the target block. S4. Substitute the height errors of each measurement point of all target blocks and the average height error of the target blocks into the image stitching algorithm for correction to improve the surround calibration accuracy.

2. The method for improving vehicle surround view calibration accuracy according to claim 1, characterized in that: There are 8 measurement points set on the target block, which are located at the four vertices and the midpoints of the four sides of the square target block.

3. A device for improving vehicle surround view calibration accuracy for implementing the method for improving vehicle surround view calibration accuracy according to any one of claims 1-2, characterized in that: include, Calibration station, used to park vehicles to be calibrated; The vehicle to be calibrated is provided with a plurality of cameras located around the vehicle; A plurality of calibration blocks are arranged on the calibration station, arranged around the vehicle parking area, and symmetrically distributed along the horizontal and vertical center axes of the calibration station; Several target blocks, one target block is set at the center of each calibration block, and the upper surface of the target block has the same theoretical height as the calibration block; Height gauge, placed at the reference point selected on the calibration station; Laser leveling device is used to obtain the height of each measuring point on the target block relative to the reference point.

4. The device for improving vehicle surround view calibration accuracy according to claim 3, characterized in that: There are four cameras installed on the vehicle to be calibrated, located on the front, rear, left and right sides of the vehicle.

5. The device for improving vehicle surround view calibration accuracy according to claim 4, characterized in that: There are 4 calibration blocks, which are respectively set at the four corners of the calibration station.

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