Camera calibration method based on teleconverter and related device

Abstract

The invention discloses a camera calibration method based on a teleconverter and a related device, and relates to the technical field of photoelectric machinery, calibration equipment comprises a jig, the teleconverter and a graph card installation assembly, and working modes comprise a debugging mode and a calibration mode. The graph card installation assembly is provided with a debugging graph card in a debugging mode, and is provided with a calibration graph card in a calibration mode. And starting the calibration equipment. And in the debugging mode, the target camera is installed in the jig, and the relative positions of the target camera, the teleconverter and the debugging diagram card are adjusted, so that the imaging of the target camera on the debugging diagram card through the teleconverter is in a clear state. In the calibration mode, by adjusting the position of the jig, the target camera is controlled to shoot the calibration graph card through the teleconverter to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field angle of the target camera; processing the plurality of calibration images by using a target release method to obtain calibration parameter values corresponding to the target camera; and writing the calibration parameter value into the target camera.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic mechanical technology, and in particular to a camera calibration method based on a teleconverter and related devices. Background Art

[0002] With the advancement of automotive camera technology, people have higher requirements for automotive camera products, and the demand for them continues to grow. AI technology can help automotive cameras achieve functions such as automatic recognition and real-time monitoring, thereby improving the intelligence of automotive cameras and providing more possibilities for their development. However, the accuracy of AI-related algorithms is closely related to the degree of image distortion, making camera internal calibration increasingly necessary.

[0003] Generally, calibrating the intrinsic parameters of a camera requires simulating a real-world working scenario. In real-world working scenarios, the calibration distance between the camera and the chart is too long. For example, the calibration distance of an ADAS camera can reach about 10 meters. Long-distance calibration not only takes up a larger area, but is also affected by many optical elements and the surrounding environment, thus affecting the calibration accuracy. Therefore, the necessity of miniaturized calibration is becoming increasingly important. To address this, a teleconverter has been added to the calibration equipment, which can simulate a long-distance working environment within a short distance. Calibration is performed by taking pictures of different poses through the teleconverter to obtain the parameters of the intrinsic parameters and complete the calibration. However, the real-world coordinate system of the virtual image simulated by the teleconverter has changed, which does not meet the flatness requirements of the chart, resulting in large reprojection errors in the calibration and inaccurate data on the focal length and principal point. Summary of the Invention

[0004] In view of the above problems, this application provides a teleconverter-based camera calibration method and related devices to solve the problem of unsatisfactory flatness of the chart caused by teleconverter simulation and improve the accuracy of camera calibration. The specific solution is as follows:

[0005] In a first aspect, the present application provides a teleconverter-based camera calibration method, the teleconverter-based camera calibration method comprising:

[0006] Starting a calibration device, the calibration device including a fixture, the teleconverter, and a chart mounting assembly, wherein the calibration device has two operating modes: a debugging mode and a calibration mode. In the debugging mode, a debugging chart is mounted on the chart mounting assembly, and in the calibration mode, a calibration chart is mounted on the chart mounting assembly.

[0007] In the debugging mode, the target camera is installed in the fixture, and the relative positions of the target camera, the teleconverter, and the debugging chart are adjusted so that the image of the debugging chart by the target camera through the teleconverter is clear;

[0008] In the calibration mode, by adjusting the position of the fixture, the target camera is controlled to shoot the calibration chart through the teleconverter to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field of view angle of the target camera; the multiple calibration images are processed using the target release method to obtain calibration parameter values corresponding to the target camera; and the calibration parameter values are written into the target camera.

[0009] In a possible implementation, adjusting the relative positions of the target camera, the teleconverter, and the adjustment chart so that the image of the adjustment chart captured by the target camera through the teleconverter is clear includes:

[0010] Controlling the target camera, the teleconverter, and the adjustment chart to be arranged in sequence in a vertical direction;

[0011] The position of the adjustment chart is adjusted in the vertical direction so that the imaging of the adjustment chart by the target camera through the teleconverter is in a clear state.

[0012] In a possible implementation, adjusting the position of the debugging chart in the vertical direction so that the target camera images the debugging chart clearly through the teleconverter includes:

[0013] In the vertical direction, the positions of the calibration charts are adjusted in descending order of distance from the teleconverter;

[0014] After each position adjustment of the debugging chart is completed, controlling the target camera to shoot the debugging chart through the teleconverter to obtain a debugging image, and detecting the imaging clarity of the debugging image;

[0015] After all positions of the debugging chart are adjusted, the position with the highest imaging clarity is used as the target position of the debugging chart, and the debugging chart is controlled to be located at the target position.

[0016] In a possible implementation, processing the multiple calibration images using a target release method to obtain calibration parameter values corresponding to the target camera includes:

[0017] Detecting the pixel coordinates of the corner points in each calibration image in a pixel coordinate system, and obtaining the world coordinates of the corner points in each calibration image in a world coordinate system, where the world coordinates are preset;

[0018] Using the pixel coordinates and the world coordinates as optimization initial values of the Zhang calibration model, taking minimizing the loss function as the optimization goal of the Zhang calibration model, and taking the calibration parameters and the world coordinate points in the world coordinate system as optimization objects, determining the calibration parameter values corresponding to the target camera, wherein the calibration parameters include intrinsic parameters and distortion coefficients, and the calibration parameter values include intrinsic parameter values and distortion coefficient values;

[0019] Format conversion is performed on the intrinsic parameter value and the distortion coefficient value.

[0020] In a possible implementation, detecting pixel coordinates of corner points in each calibration image in a pixel coordinate system includes:

[0021] By adjusting the Gaussian noise parameters, the region growing algorithm is optimized;

[0022] The pixel coordinates of the corner points in each calibration image are detected using an optimized region growing-based algorithm.

[0023] In a possible implementation, writing the calibration parameter value into the target camera includes:

[0024] Performing a CRC check on the calibration parameter value to obtain a first CRC check value;

[0025] The calibration parameter value and the first CRC check value are transmitted to the target camera so that the target camera performs a CRC check on the calibration parameter value to obtain a second CRC check value, compares the first CRC check value with the second CRC check value, and stores the calibration parameter value if the first CRC check value is the same as the second CRC check value.

[0026] A second aspect of the present application provides a teleconverter-based camera calibration device, the teleconverter-based camera calibration device comprising:

[0027] a startup module, configured to start a calibration device, the calibration device comprising a fixture, the teleconverter, and a chart mounting assembly; the calibration device having operating modes comprising a debugging mode and a calibration mode; in the debugging mode, a debugging chart is mounted on the chart mounting assembly; and in the calibration mode, a calibration chart is mounted on the chart mounting assembly;

[0028] a debugging module, configured to install the target camera in the fixture in the debugging mode and adjust the relative positions of the target camera, the teleconverter, and the debugging chart so that the target camera images the debugging chart through the teleconverter in a clear state;

[0029] The calibration module is configured to, in a calibration mode, control the target camera to capture the calibration chart through the teleconverter by adjusting the position of the fixture to obtain a plurality of calibration images, wherein the plurality of calibration images are located at different positions of the field of view of the target camera; process the plurality of calibration images using a target release method to obtain calibration parameter values corresponding to the target camera; and write the calibration parameter values into the target camera.

[0030] A third aspect of the present application provides a computer program product, comprising computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements the teleconverter-based camera calibration method of the first aspect or any implementation of the first aspect.

[0031] A fourth aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0032] The memory is used to store computer programs;

[0033] The processor is used to execute the computer program so that the electronic device can implement the camera calibration method based on the teleconverter according to the above-mentioned first aspect or any implementation method of the first aspect.

[0034] In a fifth aspect, the present application provides a computer storage medium carrying one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement the teleconverter-based camera calibration method of the above-mentioned first aspect or any implementation method of the first aspect.

[0035] By means of the above technical solution, the present application provides a camera calibration method based on a teleconverter and related devices, wherein the calibration device includes a jig, a teleconverter and a chart mounting assembly, and the working modes of the calibration device include a debugging mode and a calibration mode. In the debugging mode, the chart mounting assembly is installed with a debugging chart, and in the calibration mode, the chart mounting assembly is installed with a calibration chart. The calibration device is started. In the debugging mode, the target camera is installed in the jig, and the relative positions of the target camera, the teleconverter and the debugging chart are adjusted so that the imaging of the calibration chart by the target camera through the teleconverter is in a clear state. In the calibration mode, by adjusting the position of the jig, the target camera is controlled to shoot the calibration chart through the teleconverter to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field of view angle of the target camera; the target release method is used to process the multiple calibration images to obtain the calibration parameter values corresponding to the target camera; and the calibration parameter values are written into the target camera. This application completes the installation and debugging of the camera in debugging mode, and in calibration mode, the camera is used to shoot calibration images of different postures through a teleconverter, and the target release method is used for calibration. Since the target release method does not assume that the chart is flat, the world coordinate points and calibration parameters are optimized at the same time, which can reduce the calibration reprojection error and improve the calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0037] Figure 1 A schematic diagram of a flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application;

[0038] Figure 2 A hardware diagram of a calibration device provided in an embodiment of the present application;

[0039] Figure 3 A partial flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application;

[0040] Figure 4 A schematic diagram of another portion of the flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application;

[0041] Figure 5 A schematic diagram of a teleconverter-based camera calibration provided in an embodiment of the present application;

[0042] Figure 6 A schematic diagram of a state of a calibration image at a field of view angle provided in an embodiment of the present application;

[0043] Figure 7 A schematic diagram of another portion of the flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application;

[0044] Figure 8 A schematic structural diagram of a teleconverter-based camera calibration device provided in an embodiment of the present application;

[0045] Figure 9 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0047] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0048] The terms "first", "second" etc. in the specification of the application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0049] See also Figure 1 , Figure 1 This is a flow chart of a camera calibration method based on a teleconverter provided in an embodiment of the present application. Figure 1 As shown, a teleconverter-based camera calibration method provided in an embodiment of the present application may include steps S10 to S30, and these steps are described in detail below.

[0050] S10, starting the calibration equipment, which includes a fixture, a teleconverter, and a chart mounting assembly. The working modes of the calibration equipment include a debugging mode and a calibration mode. In the debugging mode, the chart mounting assembly is installed with a debugging chart, and in the calibration mode, the chart mounting assembly is installed with a calibration chart.

[0051] See also Figure 2 , Figure 2This is a hardware composition diagram of a calibration device provided in an embodiment of the present application. Figure 2 As shown in the figure, the calibration equipment includes a fixture A, a teleconverter B, a chart mounting assembly C, and a motor D. The calibration equipment can operate in debugging mode and calibration mode. In debugging mode, the chart mounting assembly C is installed with a debugging chart. In calibration mode, the chart mounting assembly C is installed with a calibration chart, which is generally a checkerboard chart.

[0052] Start the calibration device, and first enter the debugging mode. After debugging, make the target camera and the calibration chart image clear through the teleconverter, the calibration device enters the calibration mode, and completes the calibration by shooting the calibration chart through the teleconverter with the target camera.

[0053] S20, in the debugging mode, installing the target camera in the fixture, and adjusting the relative positions of the target camera, the teleconverter, and the debugging chart so that the image of the target camera on the debugging chart through the teleconverter is in a clear state.

[0054] In this embodiment of the present application, the calibration device, in debugging mode, controls the clamp to pick up the target camera at a specified location. The clamp can then move in the X, Y, and Z directions of three-dimensional space to place the target camera into the fixture, thereby completing the installation of the target camera in the fixture. After installation, when the fixture's buckle is pressed, the target camera's test point connects to the fixture's probe, establishing a communication link with the target camera and enabling normal operation.

[0055] After the target camera is installed on the fixture, on the one hand, the motor is driven by adjusting the motor posture, and the motor drives the fixture to move to adjust the position of the target camera in the X, Y, and Z directions. On the other hand, the position of the image card mounting assembly is adjusted up and down to dynamically adjust the relative positions of the target camera, teleconverter, and adjustment image card, so that the image of the target camera on the adjustment image card through the teleconverter is in a clear state.

[0056] In one possible implementation, the relative positions of the target camera, teleconverter, and calibration chart are first adjusted to be vertical, and then the position of the chart mounting assembly is adjusted up and down to make the image of the calibration chart from the target camera through the teleconverter the clearest. Figure 3 , Figure 3 This is a partial flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application. Figure 3 As shown, an embodiment of the present application provides a camera calibration method based on a teleconverter, wherein step S20 of "adjusting the relative positions of the target camera, the teleconverter, and the adjustment chart so that the image of the target camera on the adjustment chart through the teleconverter is in a clear state" may include steps S201 to S202, and these steps are described in detail below.

[0057] S201, controlling the target camera, the teleconverter, and the adjustment chart to be arranged in sequence in a vertical direction.

[0058] S202, adjusting the vertical position of the calibration chart so that the target camera can clearly image the calibration chart through the teleconverter.

[0059] In this embodiment, a motor drives the jig to move, thereby controlling the vertical arrangement of the target camera, teleconverter, and calibration chart. Furthermore, by adjusting the position of the chart mounting assembly up and down, the vertical position of the calibration chart is dynamically adjusted, ensuring the clearest image of the calibration chart from the target camera through the teleconverter.

[0060] In a possible implementation, the optimal vertical position of the chart mounting assembly can be determined by detecting the clarity of the chart imaged by the target camera through the teleconverter. Figure 4 , Figure 4 This is another partial flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application. Figure 4 As shown, the camera calibration method based on the teleconverter provided in the embodiment of the present application, wherein step S202 "adjusts the position of the calibration chart in the vertical direction so that the imaging of the calibration chart by the target camera through the teleconverter is in a clear state" may include steps S2021 to S2023, and these steps are described in detail below.

[0061] S2021. In the vertical direction, adjust the positions of the calibration charts in descending order of distance from the teleconverter.

[0062] In the embodiment of the present application, in the initial state, the distance between the chart mounting assembly and the teleconverter is adjusted to the maximum, and the position of the chart mounting assembly in the vertical direction is adjusted in descending order of the distance from the teleconverter, so as to adjust the position of the debug chart.

[0063] S2022: After each position adjustment of the debugging chart is completed, the target camera is controlled to shoot the debugging chart through the teleconverter to obtain a debugging image, and the imaging clarity of the debugging image is detected.

[0064] In the embodiment of the present application, after each adjustment of the position of the chart mounting assembly is completed, the position of the chart is also adjusted. The target camera is then controlled to capture the chart through the teleconverter, producing a debug image after the current adjustment of the chart position. Furthermore, an MTF detection algorithm is invoked to calculate the MTF value of the debug image. The MTF value is positively correlated with image clarity; that is, a larger MTF value indicates a higher image clarity in the debug image.

[0065] S2023: After all positions of the debugging chart are adjusted, the position with the highest imaging clarity is used as the target position of the debugging chart, and the debugging chart is controlled to be located at the target position.

[0066] In the embodiment of the present application, after the position of the chart mounting assembly is adjusted multiple times so that the distance between the chart mounting assembly and the teleconverter is adjusted to the minimum, it can be determined that all position adjustments of the debugging chart are completed. At this time, the MTF values corresponding to the multiple position adjustments can be obtained. By comparing the sizes of the MTF values, the position of the debugging chart corresponding to the maximum MTF value is used as the position with the highest imaging clarity. In this way, the target position of the speed-adjusting chart is determined, and the chart mounting assembly is adjusted to the target position, so that the debugging chart is controlled to be located at the target position.

[0067] Of course, in actual applications, the positions of the adjustment charts can be adjusted in order of distance from the teleconverter from small to large, and multiple adjustment chart positions can be configured in the initial state. This embodiment of the present application does not limit this.

[0068] S30, in the calibration mode, by adjusting the position of the fixture, controlling the target camera to shoot the calibration chart through the teleconverter to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field of view angle of the target camera; using the target release method to process the multiple calibration images to obtain the calibration parameter values corresponding to the target camera; writing the calibration parameter values into the target camera.

[0069] In the embodiments of the present application, the relative positions of the target camera, teleconverter, and debug chart of the calibration device in debug mode are used as the initial state of the calibration mode. In calibration mode, the calibration device drives the motor by adjusting the motor posture, and the motor drives the fixture to adjust the position of the target camera in the X, Y, and Z directions. This controls the target camera to capture the calibration chart through the teleconverter, thereby obtaining multiple calibration images. The multiple calibration images need to cover the entire FOV of the target camera, that is, the multiple calibration images are located at different positions within the target camera's field of view.

[0070] See also Figure 5 , Figure 5 This is a schematic diagram of a camera calibration based on a teleconverter provided in an embodiment of the present application. Figure 6 , Figure 6 This is a schematic diagram of a calibration image in the field of view provided in an embodiment of the present application. Figure 5As shown, the teleconverter and the calibration chart remain stationary. By adjusting the motor posture to drive the motor, the motor drives the fixture to move, thereby adjusting the position of the target camera in the X, Y, and Z directions. After adjusting the position of the target camera, the target camera can shoot multiple calibration images of the calibration chart through the teleconverter. Figure 5 , the target camera can take a calibration image at position 1, another calibration image at position 2, and another calibration image at position 3. Figure 6 For example, if the target camera is adjusted 9 times, 9 calibration images can be captured. The 9 calibration images can cover the entire FOV of the target camera, and each calibration image is located at a different position of the field of view. Figure 6 , adjust the target camera to position 1, and the calibration image a obtained by shooting is located in the upper left position of the entire FOV field of view. Then, adjust the target camera to position 2, and the calibration image b obtained by shooting is located in the upper middle position of the entire FOV field of view. Further, adjust the target camera to position 3, and the calibration image c obtained by shooting is located in the upper right position of the entire FOV field of view, ..., and so on. The position of the target camera is adjusted 9 times, and 9 calibration images covering the entire FOV field of view (calibration images a to i) can be captured.

[0071] Furthermore, the target release method is used to process multiple calibration images. The world coordinate points and calibration parameters of the calibration images are simultaneously optimized as variables to obtain the world coordinate points and calibration parameter values under the Zhang calibration model. Because the target release method does not assume that the chart is flat, it can offset the influence of world coordinate point errors caused by the teleconverter and improve calibration accuracy. Finally, the calibration parameter values are written to the E2 address of the target camera according to the writing rules of the target camera.

[0072] In a possible implementation, the optimal calibration parameter value can be obtained by establishing a loss function and taking function optimization as the goal. Figure 7 , Figure 7 This is another partial flow chart of a teleconverter-based camera calibration method provided in an embodiment of the present application. Figure 7 As shown, the teleconverter-based camera calibration method provided in an embodiment of the present application, wherein "processing multiple calibration images using a target release method to obtain calibration parameter values corresponding to the target camera" in step S30 may include steps S301 to S303, and these steps are described in detail below.

[0073] S301 , detecting pixel coordinates of corner points in each calibration image in a pixel coordinate system, and obtaining world coordinates of corner points in each calibration image in a world coordinate system, where the world coordinates are preset.

[0074] In an embodiment of the present application, for the obtained multiple calibration images, a region-growing-based algorithm can be used to detect the pixel coordinates of the corner points in each calibration image. The pixel coordinates refer to the coordinates in the pixel coordinate system. In addition, the world coordinates of the corner points in each calibration image can be pre-set. The world coordinates refer to the coordinates in the world coordinate system.

[0075] In practical applications, to achieve corner detection in different environments and with different image quality, the region growing algorithm can be optimized and applied to corner detection. In this regard, in the embodiment of the present application, in step S301, "detecting the pixel coordinates of the corner points in each calibration image in the pixel coordinate system" can be performed using the following steps:

[0076] The region growing algorithm is optimized by adjusting the Gaussian noise parameters. The pixel coordinates of the corner points in each calibration image are detected using the optimized region growing algorithm.

[0077] In an embodiment of the present application, before performing corner detection on each calibration image, one of the calibration images can be used to optimize the region growing-based algorithm, and the calibration image used for optimization is used as the optimized image.

[0078] The corner points in the optimized image are calibrated to obtain the number of calibrated corner points of the optimized image; then, the optimized image is corner detected using a region growing-based algorithm to obtain the number of detected corner points of the optimized image, and the number of calibrated corner points and the number of detected corner points are compared. If the compared numbers are inconsistent, the Gaussian noise parameters in the region growing-based algorithm are adjusted, and the region growing-based algorithm is used again to detect corner points of the optimized image until the compared numbers are consistent. The optimization of the region growing-based algorithm is terminated, and the optimized region growing-based algorithm is used to detect the pixel coordinates of the corner points in each calibrated image.

[0079] S302, taking pixel coordinates and world coordinates as the optimization initial values of Zhang's calibration model, taking minimizing the loss function as the optimization goal of Zhang's calibration model, taking calibration parameters and world coordinate points in the world coordinate system as optimization objects, and determining the calibration parameter values corresponding to the target camera, where the calibration parameters include intrinsic parameters and distortion coefficients, and the calibration parameter values include intrinsic parameter values and distortion coefficient values.

[0080] In an embodiment of the present application, the minimum mean square error is used to establish the loss function of the Zhang calibration model, and the loss function is optimized using the true domain reflection method. The world coordinates of the corner points in multiple calibration images are used as the optimization initial values of the Zhang calibration model, and the minimum loss function value is used as the optimization target. The world coordinate points and calibration parameters are used as optimization objects to optimize the calibration parameter values corresponding to the target camera. Of course, in actual applications, the external parameters of the target camera are also used as optimization objects together with the world coordinate points and calibration parameters. The calibration parameters include internal parameters and distortion coefficients, and correspondingly, the calibration parameter values include internal parameter values and distortion coefficient values. This can effectively avoid the problem of reduced chart flatness caused by the teleconverter.

[0081] S303: Convert the format of the internal parameter value and the distortion coefficient value.

[0082] In the embodiment of the present application, since the storage requirement of the target camera is hexadecimal, and the optimized intrinsic parameter values and distortion coefficient values are decimal, the intrinsic parameter values and distortion coefficient values can be converted into hexadecimal according to the IEEE754 conversion rules.

[0083] In one possible implementation, in the process of writing calibration parameter values to the target camera, in order to verify whether an error occurs during the data transmission to the target camera, in the embodiment of the present application, in step S30 of "writing the calibration parameter values to the target camera", the following steps can be used:

[0084] Performing a CRC check on the calibration parameter value to obtain a first CRC check value; transmitting the calibration parameter value and the first CRC check value to a target camera so that the target camera performs a CRC check on the calibration parameter value to obtain a second CRC check value, comparing the first CRC check value with the second CRC check value, and storing the calibration parameter value when the first CRC check value is the same as the second CRC check value.

[0085] CRC (Cyclic Redundancy Check) is a method for verifying whether data errors occur during data transmission. In an embodiment of the present application, before transmitting the calibration parameter value to the target camera, a CRC check can be performed on the calibration parameter value to obtain a corresponding first CRC check value. The calibration parameter value and the first CRC check value are then packaged and transmitted to the target camera. After obtaining the packaged calibration parameter value and the first CRC check value, the target camera can perform a CRC check on the calibration parameter value to obtain a corresponding second CRC check value. The first CRC check value and the second CRC check value are then compared. If the two are the same, it is determined that no error occurred during the data transmission process, and the calibration parameter value is stored. Conversely, if the two are different, it is determined that an error occurred during the data transmission process, and storage of the calibration parameter value is refused.

[0086] In practical applications, the CRC-32 table lookup method can be used for CRC verification. The parameters of the CRC-32 table lookup method are as follows: the polynomial is 0xEDB88320UL, the initial value is: 0xFFFFFFFFU, the result XOR value is FFFFFFFF, the input data is reversed, and the output data is reversed.

[0087] Through the above description, the embodiment of the present application provides a camera calibration method based on a teleconverter. After obtaining calibration images of different postures through the teleconverter, the target release method is used for calibration, and both the world coordinate points and the calibration internal parameters are optimized as parameters to improve the accuracy of the calibration. This is conducive to solving the problems of large footprint and influence of the external environment during the calibration process, reducing the difficulty of calibration and debugging equipment, simplifying the calibration and debugging steps, and at the same time helping to improve the pass rate of the calibration process.

[0088] The above describes a teleconverter-based camera calibration method provided by an embodiment of the present application. The following describes a device for executing the teleconverter-based camera calibration method. Figure 8 , Figure 8 This is a schematic diagram of the structure of a camera calibration device based on a teleconverter provided in an embodiment of the present application. Figure 8 As shown, an embodiment of the present application provides a camera calibration device based on a teleconverter, comprising:

[0089] A start-up module 10 is configured to start a calibration device, which includes a fixture, a teleconverter, and a chart mounting assembly. The calibration device operates in two modes: a debug mode and a calibration mode. In the debug mode, a debug chart is mounted on the chart mounting assembly. In the calibration mode, a calibration chart is mounted on the chart mounting assembly.

[0090] The debugging module 20 is used to install the target camera in the fixture in the debugging mode and adjust the relative positions of the target camera, the teleconverter and the debugging chart so that the image of the target camera on the debugging chart through the teleconverter is clear;

[0091] The calibration module 30 is used to control the target camera to capture the calibration chart through the teleconverter by adjusting the position of the fixture in the calibration mode to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field of view angle of the target camera; use the target release method to process the multiple calibration images to obtain calibration parameter values corresponding to the target camera; and write the calibration parameter values into the target camera.

[0092] In one possible implementation, the debugging module 20 for adjusting the relative positions of the target camera, the teleconverter, and the debugging chart so that the image of the target camera on the debugging chart through the teleconverter is clear is specifically configured to:

[0093] The target camera, the teleconverter and the adjustment chart are controlled to be arranged in sequence in the vertical direction; the position of the adjustment chart is adjusted in the vertical direction so that the image of the adjustment chart by the target camera through the teleconverter is in a clear state.

[0094] In one possible implementation, the debugging module 20 for adjusting the vertical position of the debugging chart so that the target camera images the debugging chart in a clear state through the teleconverter is specifically configured to:

[0095] In the vertical direction, the position of the debugging chart is adjusted in descending order of the distance from the teleconverter; after each position adjustment of the debugging chart is completed, the target camera is controlled to shoot the debugging chart through the teleconverter to obtain a debugging image, and the imaging clarity of the debugging image is detected; after all position adjustments of the debugging chart are completed, the position with the highest imaging clarity is used as the target position of the debugging chart, and the debugging chart is controlled to be located at the target position.

[0096] In one possible implementation, the calibration module 30 for processing a plurality of calibration images using a target release method to obtain calibration parameter values corresponding to a target camera is specifically configured to:

[0097] Detect the pixel coordinates of the corner points in each calibration image in the pixel coordinate system, and obtain the world coordinates of the corner points in each calibration image in the world coordinate system, where the world coordinates are preset; use the pixel coordinates and the world coordinates as the optimization initial values of Zhang's calibration model, take the minimum loss function as the optimization goal of Zhang's calibration model, take the calibration parameters and the world coordinate points in the world coordinate system as the optimization objects, determine the calibration parameter values corresponding to the target camera, the calibration parameters include intrinsic parameters and distortion coefficients, and the calibration parameter values include intrinsic parameter values and distortion coefficient values; convert the format of the intrinsic parameter values and the distortion coefficient values.

[0098] In one possible implementation, the calibration module 30 for detecting pixel coordinates of corner points in each calibration image in a pixel coordinate system is specifically configured to:

[0099] The region growing algorithm is optimized by adjusting the Gaussian noise parameters. The pixel coordinates of the corner points in each calibration image are detected using the optimized region growing algorithm.

[0100] In one possible implementation, the calibration module 30 for writing the calibration parameter value into the target camera is specifically configured to:

[0101] Performing a CRC check on the calibration parameter value to obtain a first CRC check value; transmitting the calibration parameter value and the first CRC check value to a target camera so that the target camera performs a CRC check on the calibration parameter value to obtain a second CRC check value, comparing the first CRC check value with the second CRC check value, and storing the calibration parameter value when the first CRC check value is the same as the second CRC check value.

[0102] It should be noted that the detailed functions of each module in the embodiment of the present application can be found in the corresponding disclosed part of the above-mentioned embodiment of the camera calibration method based on the teleconverter, and will not be repeated here.

[0103] The present application also provides an electronic device. Figure 9 , Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device in the embodiment of the present application may include, but is not limited to, fixed terminals such as mobile phones, laptops, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Figure 9 The electronic device shown is merely an example and should not limit the functions and scope of use of the embodiments of the present application.

[0104] like Figure 9 As shown, the electronic device may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 901, which can perform various appropriate actions and processes based on programs stored in a read-only memory (ROM) 902 or programs loaded from a storage device 908 into a random access memory (RAM) 903. When the electronic device is powered on, the RAM 903 also stores various programs and data required for the operation of the electronic device. The processing device 901, ROM 902, and RAM 903 are interconnected via a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0105] Typically, the following devices may be connected to the I / O interface 905: an input device 906 including, for example, a touch screen, a touchpad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; an output device 907 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 908 including, for example, a memory card, a hard disk, etc.; and a communication device 909. The communication device 909 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although Figure 9 The electronic device is shown with various devices, but it should be understood that it is not required to implement or possess all of the devices shown. More or fewer devices may be implemented or possessed instead.

[0106] An embodiment of the present application also provides a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any of the teleconverter-based camera calibration methods provided in the embodiments of the present application.

[0107] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the teleconverter-based camera calibration methods provided in the embodiments of the present application.

[0108] It should also be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided in this application, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines.

[0109] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including application-specific integrated circuits, special CPUs, special memories, special components, etc. In general, all functions performed by computer programs can be easily implemented with corresponding hardware, and the specific hardware structures used to implement the same function can also be diverse, such as analog circuits, digital circuits or special circuits, etc. However, for the present application, software program implementation is a better implementation method in most cases. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer's floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disk, etc., and includes a number of instructions to enable a computer device (which can be a personal computer, training equipment, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

[0110] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0111] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, a computer, a training device or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website, a computer, a training device or a data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

Claims

1. A camera calibration method based on a teleconverter, characterized in that: The teleconverter-based camera calibration method includes: Starting a calibration device, the calibration device including a fixture, the teleconverter, and a chart mounting assembly, wherein the calibration device has two operating modes: a debugging mode and a calibration mode. In the debugging mode, a debugging chart is mounted on the chart mounting assembly, and in the calibration mode, a calibration chart is mounted on the chart mounting assembly. In the debugging mode, the target camera is installed in the fixture, and the relative positions of the target camera, the teleconverter, and the debugging chart are adjusted so that the image of the debugging chart by the target camera through the teleconverter is clear; In the calibration mode, by adjusting the position of the fixture, the target camera is controlled to shoot the calibration chart through the teleconverter to obtain multiple calibration images, and the multiple calibration images are located at different positions of the field of view angle of the target camera; the multiple calibration images are processed using the target release method to obtain calibration parameter values corresponding to the target camera; and the calibration parameter values are written into the target camera.

2. The teleconverter-based camera calibration method according to claim 1, wherein: The adjusting the relative positions of the target camera, the teleconverter, and the adjustment chart so that the image of the adjustment chart by the target camera through the teleconverter is in a clear state includes: Controlling the target camera, the teleconverter, and the adjustment chart to be arranged in sequence in a vertical direction; The position of the adjustment chart is adjusted in the vertical direction so that the imaging of the adjustment chart by the target camera through the teleconverter is in a clear state.

3. The teleconverter-based camera calibration method according to claim 2, wherein: The adjusting the position of the debugging chart in the vertical direction so that the target camera images the debugging chart in a clear state through the teleconverter includes: In the vertical direction, the positions of the calibration charts are adjusted in descending order of distance from the teleconverter; After each position adjustment of the debugging chart is completed, controlling the target camera to shoot the debugging chart through the teleconverter to obtain a debugging image, and detecting the imaging clarity of the debugging image; After all positions of the debugging chart are adjusted, the position with the highest imaging clarity is used as the target position of the debugging chart, and the debugging chart is controlled to be located at the target position.

4. The teleconverter-based camera calibration method according to claim 1, wherein: The process of processing the plurality of calibration images using a target release method to obtain calibration parameter values corresponding to the target camera includes: Detecting the pixel coordinates of the corner points in each calibration image in a pixel coordinate system, and obtaining the world coordinates of the corner points in each calibration image in a world coordinate system, where the world coordinates are preset; Using the pixel coordinates and the world coordinates as optimization initial values of the Zhang calibration model, taking minimizing the loss function as the optimization goal of the Zhang calibration model, and taking the calibration parameters and the world coordinate points in the world coordinate system as optimization objects, determining the calibration parameter values corresponding to the target camera, wherein the calibration parameters include intrinsic parameters and distortion coefficients, and the calibration parameter values include intrinsic parameter values and distortion coefficient values; Format conversion is performed on the intrinsic parameter value and the distortion coefficient value.

5. The teleconverter-based camera calibration method according to claim 4, wherein: Detecting the pixel coordinates of the corner points in each calibration image in the pixel coordinate system includes: By adjusting the Gaussian noise parameters, the region growing algorithm is optimized; The pixel coordinates of the corner points in each calibration image are detected using an optimized region growing-based algorithm.

6. The teleconverter-based camera calibration method according to claim 1, wherein: Writing the calibration parameter value into the target camera includes: Performing a CRC check on the calibration parameter value to obtain a first CRC check value; The calibration parameter value and the first CRC check value are transmitted to the target camera so that the target camera performs a CRC check on the calibration parameter value to obtain a second CRC check value, compares the first CRC check value with the second CRC check value, and stores the calibration parameter value if the first CRC check value is the same as the second CRC check value.

7. A camera calibration device based on a teleconverter, characterized in that: The camera calibration device based on the teleconverter includes: a startup module, configured to start a calibration device, the calibration device comprising a fixture, the teleconverter, and a chart mounting assembly; the calibration device having operating modes comprising a debugging mode and a calibration mode; in the debugging mode, a debugging chart is mounted on the chart mounting assembly; and in the calibration mode, a calibration chart is mounted on the chart mounting assembly; a debugging module, configured to install the target camera in the fixture in the debugging mode and adjust the relative positions of the target camera, the teleconverter, and the debugging chart so that the target camera images the debugging chart through the teleconverter in a clear state; The calibration module is configured to, in a calibration mode, control the target camera to capture the calibration chart through the teleconverter by adjusting the position of the fixture to obtain a plurality of calibration images, wherein the plurality of calibration images are located at different positions of the field of view of the target camera; process the plurality of calibration images using a target release method to obtain calibration parameter values corresponding to the target camera; and write the calibration parameter values into the target camera.

8. A computer program product, characterized in that The invention comprises computer-readable instructions, which, when executed on an electronic device, enable the electronic device to implement the teleconverter-based camera calibration method according to any one of claims 1 to 6.

9. An electronic device, characterized in that: comprising at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the electronic device can implement the camera calibration method based on the teleconverter as described in any one of claims 1 to 6.

10. A computer storage medium, characterized in that The storage medium carries one or more computer programs, and when the one or more computer programs are executed by an electronic device, the electronic device can implement the teleconverter-based camera calibration method as described in any one of claims 1 to 6.

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