Windshield head-up display installation distortion lookup table acquisition method

Abstract

The invention provides a method for improving the display precision of a windshield head-up display, and belongs to the field of windshield display, and the method comprises the steps: displaying a rectangular grid picture at an interval of 1 degree on the windshield head-up display, photographing the windshield head-up display picture at an eye position through a calibrated camera, then recognizing a photographing result, recognizing the coordinates of grid points, and displaying the coordinates of the grid points on the windshield head-up display. The method comprises the following steps of: firstly, acquiring a distortion lookup table, converting the distortion lookup table into a windshield head-up display coordinate, calculating the coordinates of other pixel points by using bilinear interpolation, finally calculating a corresponding relation table between the actual coordinate position and the theoretical position of each pixel of a windshield head-up display picture, correcting the original distortion lookup table according to the corresponding relation table, and generating a new corrected distortion lookup table. The method has the characteristics of high detection speed and high precision, and is implemented after the system is installed, so that errors caused by later installation and processing precision can be solved, and the installation and adjustment efficiency of the windshield head-up display is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of windshield head-up display technology, specifically relating to a method for obtaining a lookup table of windshield head-up display installation distortion. Background Technology

[0002] A head-up display (HUD) is a device that projects information directly onto the windshield in front of the driver. It displays important information such as speed and altitude on the windshield, allowing the driver to keep their line of sight at eye level, reducing the number of times they need to look down at the instruments, and improving safety and efficiency.

[0003] Display accuracy is a very important indicator for windshield head-up displays, as it directly affects the accuracy of the display. The windshield HUD glass is curved, causing distortion when the image is projected onto the glass, thus requiring distortion correction. The current approach involves first calculating the correspondence between each pixel before and after distortion based on design parameters, saving this as a separate file called a distortion lookup table. Then, based on the distortion lookup table, the output image undergoes pre-distortion correction before being projected onto the windshield, resulting in a normal image.

[0004] However, due to manufacturing errors in the windshield and subsequent installation errors, the actual distortion effect differs from the theoretical parameters, potentially leading to excessive display accuracy and problems such as image distortion and deformation. Once the equipment is installed, adjustments are quite difficult.

[0005] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of display accuracy exceeding the standard caused by the discrepancy between actual distortion and theoretical distortion parameters.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for obtaining a windshield head-up display installation distortion lookup table, comprising: Using the theoretical distortion lookup table T1, a pre-distorted 1° rectangular grid image is generated from the 1° rectangular grid image and output to the windshield head-up display. Using a calibrated camera, the grid image displayed on the windshield head-up display is captured at eye level, generating image img1; The image img1 is converted to a grayscale image, then adaptively binarized, and the largest connected component is selected as the image img2. Generate X-shaped convolution kernels and cross-shaped convolution kernels, and perform convolution operations on img2 respectively to obtain the coordinates of the grid center in the camera and the coordinates of all grid points in the camera; Convert the coordinates of the grid points on the camera to the pixel coordinates of the windshield HUD image source; Based on the correspondence between the theoretical and actual positions of the grid points, a secondary distortion lookup table T2 is generated to represent the correspondence between the theoretical and actual positions of all pixels in the windshield HUD. The original distortion lookup table T1 and the secondary distortion lookup table T2 are merged to generate the final distortion lookup table T3.

[0008] The windshield head-up display installation distortion lookup table acquisition method provided by the present invention also has the following technical feature: the calibrated camera is a distortion-free camera with a resolution of 4000*3000.

[0009] The windshield head-up display (HUD) installation distortion lookup table acquisition method provided by this invention also has the following technical feature: the step of converting the coordinates of the grid points on the camera into the pixel coordinates of the windshield HUD image source includes: Based on the correspondence between camera pixels and field of view, the pixel coordinates of the grid points on the camera are converted into field of view coordinates, and then further converted into windshield head-up display pixel coordinates.

[0010] The windshield head-up display installation distortion lookup table acquisition method provided by the present invention also has the following technical feature: the correspondence between the theoretical value and the actual value of each pixel of the windshield head-up display is calculated using bilinear interpolation.

[0011] The windshield head-up display installation distortion lookup table acquisition method provided by the present invention also has the following technical feature: the fusion of the original distortion lookup table T1 and the secondary distortion lookup table T2 includes: using the output of the original distortion lookup table T1 as the input of the secondary distortion lookup table T2.

[0012] Beneficial effects: The distortion lookup table obtained by the windshield head-up display installation distortion lookup table provided by this invention can be used in the windshield head-up display assembly process. The measured error can be controlled within 10 minutes. It is also easy to implement and can be corrected after assembly. This solves the problem of decreased accuracy caused by production, processing and installation errors, and significantly improves the assembly progress of the windshield head-up display. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A flowchart of the method provided as an exemplary embodiment of this disclosure; Figure 2 This is the original mesh diagram in an exemplary embodiment of this disclosure; Figure 3 A schematic diagram showing a pre-distorted mesh diagram in an exemplary embodiment of this disclosure; Figure 4 A schematic diagram showing images captured in exemplary embodiments of the present disclosure; Figure 5 This is a schematic diagram of the image img2, which is the largest connected component after binarization, in an exemplary embodiment of this disclosure. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0016] In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0017] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of these terms in this invention based on the specific circumstances.

[0019] like Figure 1-5 As shown, this embodiment of the invention provides a method for obtaining a lookup table for windshield head-up display installation distortion, including: Step S101: Using the theoretical distortion lookup table T1, generate a pre-distorted 1° rectangular grid image from the 1° rectangular grid image and output it to the windshield head-up display for display. Step S102: Using the calibrated camera, take a picture of the grid image displayed on the windshield head-up display from eye level to generate image img1; Step S103: Convert image img1 to generate a grayscale image, then perform adaptive binarization on it, and select the largest connected component as image img2; Step S104: Generate X-shaped convolution kernels and cross-shaped convolution kernels, both with a template size of 1°*1°. Perform convolution operations on img2 respectively to obtain the coordinates of the grid center in the camera and the coordinates of all grid points in the camera, and generate images img3 and img4. Step S105: Binarize image img3 using 254 as the threshold; the centroid coordinates of the connected component closest to the image center are the grid center coordinates. Step S106: Binarize the image img4 with a threshold of 254. The centroid coordinates of all connected components are the grid point coordinates. Then, sort all coordinates according to the grid center coordinates. Step S107: Convert the coordinates of the grid points on the camera to the pixel coordinates of the windshield flat-screen image source; Step S108: Based on the correspondence between the theoretical and actual positions of the grid points, generate a secondary distortion lookup table T2 to represent the correspondence between the theoretical and actual positions of all pixels in the windshield HUD; Step S109: Merge the original distortion lookup table T1 with the secondary distortion lookup table T2 to generate the final tertiary distortion lookup table T3.

[0020] In some embodiments, the calibrated camera is a distortion-free camera with a resolution of 4000*3000.

[0021] In some embodiments, converting the coordinates of the grid points on the camera into pixel coordinates of the windshield HUD image source includes: Based on the correspondence between camera pixels and field of view, the pixel coordinates of the grid points on the camera are converted into field of view coordinates, and then further converted into windshield head-up display pixel coordinates.

[0022] In some embodiments, the correspondence between the theoretical and actual values ​​of each pixel in the windshield head-up display is calculated using bilinear interpolation.

[0023] In some embodiments, fusing the original distortion lookup table T1 and the secondary distortion lookup table T2 includes using the output of the original distortion lookup table T1 as the input of the secondary distortion lookup table T2.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method for obtaining a lookup table for windshield head-up display installation distortion, characterized in that, include: Using the theoretical distortion lookup table T1, a pre-distorted 1° rectangular grid image is generated from the 1° rectangular grid image and output to the windshield head-up display. Using a calibrated camera, the grid image displayed on the windshield head-up display is captured at eye level, generating image img1; The image img1 is converted to a grayscale image, then adaptively binarized, and the largest connected component is selected as the image img2. Generate X-shaped convolution kernels and cross-shaped convolution kernels, and perform convolution operations on img2 respectively to obtain the coordinates of the grid center in the camera and the coordinates of all grid points in the camera; Convert the coordinates of the grid points on the camera to the pixel coordinates of the windshield HUD image source; Based on the correspondence between the theoretical and actual positions of the grid points, a secondary distortion lookup table T2 is generated to represent the correspondence between the theoretical and actual positions of all pixels in the windshield HUD. The original distortion lookup table T1 and the secondary distortion lookup table T2 are merged to generate the final distortion lookup table T3.

2. The method for obtaining the windshield head-up display installation distortion lookup table according to claim 1, characterized in that, The calibrated camera is a distortion-free camera with a resolution of 4000*3000.

3. The method for obtaining the windshield head-up display installation distortion lookup table according to claim 1, characterized in that, The process of converting the coordinates of the grid points on the camera into pixel coordinates of the windshield HUD image source includes: Based on the correspondence between camera pixels and field of view, the pixel coordinates of the grid points on the camera are converted into field of view coordinates, and then further converted into windshield head-up display pixel coordinates.

4. The method for obtaining the windshield head-up display installation distortion lookup table according to claim 1, characterized in that, The correspondence between the theoretical and actual values ​​of each pixel in the windshield HUD is calculated using bilinear interpolation.

5. The method for obtaining the windshield head-up display installation distortion lookup table according to claim 1, characterized in that, The fusion of the original distortion lookup table T1 and the secondary distortion lookup table T2 includes: using the output of the original distortion lookup table T1 as the input of the secondary distortion lookup table T2.

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