A method and system for distortion correction in wide-angle cameras

Abstract

This specification provides a method and system for distortion correction of a wide-angle camera, using an adjustment device and a calibration component. The method includes: determining multiple limit movement distances for the calibration component to move on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component; moving the calibration component to multiple edge positions by adjusting the adjustment device based on the multiple limit movement distances; adjusting the orientation of the calibration component by rotating it by adjusting the adjustment device at each edge position, and taking multiple photos with the wide-angle camera to determine the standard orientation of the calibration component at each edge position and first angle data of the rotation of the calibration component by adjusting the adjustment device at the standard orientation; and determining distortion correction parameters for the wide-angle camera based on the first angle data at each edge position.

Description

Technical Field

[0001] This specification relates to the field of image processing technology, and in particular to a method and system for distortion correction of wide-angle cameras. Background Technology

[0002] Wide-angle cameras, with their wide field of view, can capture more of the scene within a limited distance, making them widely used in various fields such as measurement and inspection. For example, wide-angle cameras can be used for distance measurement in medical imaging. Specifically, in medical imaging, such as X-ray imaging, adjusting exposure parameters and radiation range is challenging due to differences in patients' physiological characteristics. While experienced physicians can adjust based on experience, it's difficult to precisely adapt to each patient, especially for less experienced physicians who may cause overexposure or blurry images due to inappropriate parameters. Therefore, binocular imaging distance measurement technology has been introduced into medical imaging. Binocular imaging distance measurement technology mimics the human eye, automatically adjusting exposure parameters by recognizing patient characteristics (such as body thickness) to reduce radiation exposure and improve examination efficiency. Wide-angle cameras, due to their wide field of view, can be applied to binocular distance measurement imaging technology, such as suspended DR (Digital Radiography), which can automatically locate the patient and adjust exposure parameters. However, wide-angle cameras are prone to distortion, such as radial and tangential distortion, which can affect the accuracy of their detection and measurement. Therefore, distortion correction processing is required for wide-angle cameras; otherwise, the accuracy of the results obtained from detection and measurement using wide-angle cameras will be low. Summary of the Invention

[0003] This specification provides one or more embodiments of a method for distortion correction of a wide-angle camera, using an adjustment device and a calibration member. The adjustment device is configured to: drive the calibration member to move to adjust the position of the calibration member, and drive the calibration member to rotate to adjust the attitude of the calibration member. The method includes the following steps: determining a plurality of limit movement distances of the calibration member on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration member, and the distance between the wide-angle camera and the calibration member; the plurality of limit movement distances reflect the distances the calibration member moves from an initial position to the specified position. The calibration component moves a distance to multiple edge positions within the field of view of the wide-angle camera; based on the multiple extreme movement distances, the calibration component is driven to move by the adjustment device to reach each of the multiple edge positions; at each edge position, the calibration component's attitude is adjusted by rotating it by the adjustment device, and multiple shots are taken by the wide-angle camera to determine the standard attitude of the calibration component at each edge position and the first angle data of the adjustment device driving the calibration component to rotate at the standard attitude; and based on the first angle data at each edge position, the distortion correction parameters of the wide-angle camera are determined.

[0004] In some embodiments, determining the distortion correction parameters of the wide-angle camera based on the first angle data at each of the edge positions includes: determining multiple traversal positions of the calibration member on the preset moving plane within the field of view of the wide-angle camera; driving the calibration member to move to each of the traversal positions via the adjustment device; at each traversal position, adjusting the orientation of the calibration member by driving the calibration member to rotate via the adjustment device based on the first angle data at each of the edge positions; and taking multiple shots via the wide-angle camera to determine the standard orientation of the calibration member at each of the traversal positions and the second angle data of the adjustment device driving the calibration member to rotate at the standard orientation; and determining the distortion correction parameters of the wide-angle camera based on the first angle data at each of the edge positions and the second angle data at each of the traversal positions.

[0005] In some embodiments, when the calibration element is in the initial position, the center point of the calibration element is located on the optical axis of the wide-angle camera; the step of driving the calibration element to move and adjust the position of the calibration element includes: driving the calibration element to translate along a first direction or its opposite direction and driving the calibration element to translate along a second direction or its opposite direction; the first direction is perpendicular to the second direction; both the first direction and the second direction are perpendicular to the optical axis; the step of determining multiple limit movement distances of the calibration element on a preset movement plane perpendicular to the optical axis of the wide-angle camera based on the field of view of the wide-angle camera, the size parameters of the calibration element, and the distance between the wide-angle camera and the calibration element includes: determining a first limit distance, a second limit distance, a third limit distance, and a fourth limit distance of movement of the calibration element along the first direction, along the opposite direction, along the second direction, and along the opposite direction, on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration element, and the distance between the wide-angle camera and the calibration element.

[0006] In some embodiments, the field of view includes a horizontal field of view and a vertical field of view; determining multiple limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component further includes: determining a horizontal field of view width based on the horizontal field of view and the distance between the wide-angle camera and the calibration component; determining a vertical field of view height based on the vertical field of view and the distance between the wide-angle camera and the calibration component; determining a first limit distance for the calibration component to move along the first direction and a second limit distance for the calibration component to move along the opposite direction based on the horizontal field of view width and the size parameters of the calibration component; and determining a third limit distance for the calibration component to move along the second direction and a fourth limit distance for the calibration component to move along the opposite direction based on the vertical field of view height and the size parameters of the calibration component.

[0007] In some embodiments, the plurality of traversal positions form an array within the field of view of the wide-angle camera, the rows of the array being parallel to the first direction and the columns of the array being parallel to the second direction; the closer the traversal position in the array is to the edge position from its initial position along the first direction or its opposite direction, the larger the rotation step size of the adjustment device driving the calibration element to rotate; the closer the traversal position in the array is to the edge position from its initial position along the second direction and its opposite direction, the larger the rotation step size of the adjustment device driving the calibration element to rotate.

[0008] In some embodiments, the step of driving the calibration element to move to each of the traversal positions via the adjustment device includes: driving the calibration element to translate along a third direction or its opposite direction; the third direction is parallel to the optical axis of the wide-angle camera; the method for determining the interval distance between the wide-angle camera and the calibration element includes: placing the calibration element in an initial position; adjusting the position of the calibration element by translating the calibration element along the third direction or its opposite direction via the adjustment device based on the initial position, so that the ratio of the imaging area of ​​the calibration element to the area of ​​the imaging region corresponding to the field of view of the wide-angle camera is a preset threshold; and using the distance between the adjusted calibration element and the wide-angle camera as the interval distance.

[0009] In some embodiments, driving the calibration element to rotate and adjust its attitude includes: driving the calibration element to rotate about a first axis and driving the calibration element to rotate about a second axis; the first axis is perpendicular to the second axis; both the first axis and the second axis are perpendicular to the optical axis; driving the calibration element to rotate and adjust its attitude by the adjustment device includes: driving the calibration element to rotate about the first axis and / or driving the calibration element to rotate about the second axis by the adjustment device; the first angle data and the second angle data include: the angle at which the adjustment device drives the calibration element to rotate along the first axis, and / or the angle at which the adjustment device drives the calibration element to rotate about the second axis.

[0010] In some embodiments, the step of driving the calibration member to rotate and adjusting the attitude of the calibration member further includes: driving the calibration member to rotate about a third axis; the third axis is parallel to the optical axis of the wide-angle camera; the step of driving the calibration member to rotate and adjusting the attitude of the calibration member through the adjustment device further includes: driving the calibration member to rotate about the third axis through the adjustment device; the first angle data includes the angle by which the adjustment device drives the calibration member to rotate about the third axis.

[0011] In some embodiments, the method further includes: performing distortion correction calibration on the wide-angle camera in the medical imaging device based on the distortion correction parameters of the wide-angle camera; the wide-angle camera in the medical imaging device is used for binocular imaging ranging.

[0012] This specification provides one or more embodiments of a system for distortion correction of a wide-angle camera. The system includes an adjustment device, a calibration component, and a processor, the processor being communicatively connected to the adjustment device. The processor includes a calibration component control module and a data analysis module. The calibration component control module is configured to: drive the calibration component to move to adjust its position; and drive the calibration component to rotate to adjust its attitude. The data analysis module is configured to: determine multiple limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component. Multiple extreme movement distances reflect the distances the calibration component moves from its initial position to multiple edge positions within the field of view of the wide-angle camera. Based on these multiple extreme movement distances, the calibration component is moved by the adjustment device to reach each of the multiple edge positions. At each edge position, the calibration component's attitude is adjusted by rotating it using the adjustment device, and multiple shots are taken using the wide-angle camera to determine the standard attitude of the calibration component at each edge position and the first angle data of the rotation of the calibration component by the adjustment device at the standard attitude. Based on the first angle data at each edge position, the distortion correction parameters of the wide-angle camera are determined. Attached Figure Description

[0013] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0014] Figure 1 These are exemplary schematic diagrams illustrating barrel distortion according to some embodiments of this specification;

[0015] Figure 2(a) is an exemplary schematic diagram of a chessboard grid according to some embodiments of this specification;

[0016] Figure 2(b) is an exemplary schematic diagram of the corner points of a chessboard grid according to some embodiments of this specification;

[0017] Figure 3 This is an exemplary flowchart of a method for distortion correction of a wide-angle camera according to some embodiments of this specification;

[0018] Figure 4 These are exemplary schematic diagrams of the field of view according to some embodiments of this specification;

[0019] Figure 5This is an exemplary schematic diagram of the image acquisition area of ​​a wide-angle camera and a calibration component according to some embodiments of this specification;

[0020] Figure 6 This is an exemplary flowchart of a method for determining distortion correction parameters for a wide-angle camera according to some embodiments of this specification;

[0021] Figure 7 These are exemplary schematic diagrams of adjustment devices, calibration components, and wide-angle cameras according to some embodiments of this specification;

[0022] Figure 8 This is an exemplary flowchart of a method for determining multiple limit movement distances according to some embodiments of this specification;

[0023] Figure 9 This is a schematic diagram of the structure of a system for distortion correction of a wide-angle camera, as shown in some embodiments of this specification. Figure 1 ;

[0024] Figure 10 This is a schematic diagram of a system for distortion correction of a wide-angle camera, as shown in some embodiments of this specification.

[0025] Figure 11 These are schematic diagrams of the structure of the moving component according to some embodiments of this specification;

[0026] Figure 12 This is a schematic diagram of the structure of the Y-axis moving unit according to some embodiments of this specification;

[0027] Figure 13 This is a schematic diagram of the structure of the rotating assembly shown in some embodiments of this specification;

[0028] Figure 14 This is a cross-sectional view of the rotating assembly shown in some embodiments of this specification;

[0029] Figure 15 This is a structural schematic diagram of the X-axis rotary seat according to some embodiments of this specification.

[0030] In the picture:

[0031] 100. Distortion correction system;

[0032] 1. Adjust the equipment;

[0033] 11. Moving component; 111. X-axis moving unit; 112. Y-axis moving unit; 113. Z-axis moving unit; 1101. Motor; 1102. Transmission unit; 11021. Fixing component; 11022. Ball screw; 11023. Connecting component; 110231. Connecting block; 110232. Connecting plate; 1103. First sensing component; 11031. Resistor; 11032. Slider; 1104. L-shaped connecting component;

[0034] 12. Rotating component;

[0035] 121. X-axis rotation unit; 1211. X-axis rotation motor; 1212. X-axis coupling; 1213. X-axis rotation shaft; 12131. Protrusion; 1214. X-axis rotation seat; 12141. Through hole; 1215. First bearing seat; 1216. First support member;

[0036] 122. Y-axis rotary unit; 1221. Y-axis rotary motor; 1222. Gear transmission unit; 12221. First gear; 12222. Second gear; 1223. Bearing; 1224. Elastic retaining ring;

[0037] 123. Z-axis rotary unit; 1231. Z-axis rotary motor; 1232. Z-axis coupling; 1233. Z-axis rotary shaft; 12331. Calibration plate; 1234. Second bearing seat; 1235. Second support component;

[0038] 13. Wide-angle camera mount; 14. Base plate;

[0039] 2. Calibration parts;

[0040] 200. Wide-angle camera. Detailed Implementation

[0041] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0042] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0043] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0044] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0045] Wide-angle cameras are prone to distortion, such as radial and tangential distortion. Tangential distortion is often related to the camera's manufacturing and assembly processes, such as assembly issues causing the lens and the camera's imaging plane to be non-parallel. This distortion is unavoidable and varies from camera to camera. Radial distortion in wide-angle cameras is a type of barrel distortion, such as... Figure 1 As shown, the magnification in the central region of the optical axis within the field of view is much greater than that in the edge regions, such as... Figure 1 The distortion at the edges is very large, especially at the four corners. Without distortion correction, the acquired image would be unusable. Therefore, distortion correction is necessary for the wide-angle camera to correct the distortion of its optical lens.

[0046] In some embodiments, a crucial step in correcting optical lens distortion is the detection of feature points on the calibration component. During distortion correction, images of the calibration component from different angles are captured using a wide-angle camera to determine the coordinates of these feature points. For example, the calibration component is a checkerboard calibration plate, such as... Figure 2(a)-Figure 2(b) As shown, the corner points on the checkerboard calibration board are used as feature points. Each corner point is the intersection of four black and white squares on the calibration board. The outlines of the four black and white squares are vertically and horizontally distributed, forming two sets of intersecting grid lines. However, for wide-angle cameras, the image edge distortion is too large, resulting in significant deformation and displacement of the corner points, affecting corner point acquisition. Therefore, the orientation of the calibration component needs to be adjusted at the image edge positions of wide-angle cameras to obtain effective corner points.

[0047] In some embodiments, the orientation of the calibration component can be pre-adjusted, and various calibration methods can be used to calibrate the wide-angle summation intrinsic and extrinsic parameters, such as deep learning algorithms and corner detection methods (e.g., convolution algorithms or Harris algorithms). In some embodiments, the operator manually calibrates the wide-angle camera. Due to the lens imaging principle, the distorted image seen by the human eye is the opposite of the actual calibration component, which does not conform to human operating habits. Moreover, each person adjusts the angle inconsistently, which is time-consuming and laborious. It also leads to poor quality of the collected feature points, which in turn reduces the calibration accuracy. In some cases, feature points at the corners of the image may not be collected, resulting in distortion correction calibration failure.

[0048] This specification provides a method for distortion correction of a wide-angle camera using several embodiments. The method employs an adjustment device and a calibration element to perform the distortion correction operation. In some embodiments, the adjustment device is configured to: drive the calibration element to move and adjust its position; and drive the calibration element to rotate and adjust its orientation. The movement of the calibration element refers to its movement on a predetermined plane perpendicular to the optical axis of the wide-angle camera, such as translation with at least two degrees of freedom. Adjusting the position of the calibration element refers to adjusting its position within the field of view of the wide-angle camera. Rotating the calibration element refers to its rotation about at least one axis perpendicular to the optical axis of the wide-angle camera, such as rotation about a first axis and a second axis described below. In some embodiments, adjusting the position of the calibration element can adjust its position on the imaging plane, and adjusting the orientation of the calibration element can adjust the angular relationship between the calibration element and the imaging plane of the wide-angle camera.

[0049] An adjustment device refers to a device or apparatus capable of driving a calibration component to move or rotate. In some embodiments, the adjustment device may include a moving component, a rotating component, and a wide-angle camera mount, with the calibration component disposed on the rotating component, the rotating component connected to the moving component, and the moving component and the wide-angle camera mount spaced apart.

[0050] A calibration element is a reference object used in the measurement, calibration, or standardization process. Calibration is achieved by extracting feature points on the calibration element (see related descriptions below for details). In some embodiments, the calibration element can be a checkerboard calibration plate. When the calibration element is a checkerboard calibration plate, driving the calibration element to move and adjust its position means driving the checkerboard calibration element to move on a preset movement plane perpendicular to the optical axis of the wide-angle camera, thereby adjusting the position of the checkerboard calibration plate within the field of view of the wide-angle camera. When the calibration element is a checkerboard calibration plate, driving the calibration element to rotate and adjust its orientation means driving the checkerboard calibration plate to rotate about at least one axis perpendicular to the optical axis of the wide-angle camera, thereby adjusting the orientation of the corner points on the checkerboard calibration plate (i.e., the angle between the checkerboard calibration plate and the imaging plane of the wide-angle camera).

[0051] For more information on adjustment devices, calibration components, wide-angle cameras, and preset moving planes, please refer to the following text (e.g. Figure 3 The relevant descriptions in (etc.).

[0052] Figure 3 This is an exemplary flowchart illustrating a method for distortion correction of a wide-angle camera according to some embodiments of this specification. Figure 3 As shown, process 300 includes the following steps. In some embodiments, process 300 may be executed by a processor of a system for wide-angle camera distortion correction (hereinafter referred to as the "distortion correction system"). For more information on systems for wide-angle camera distortion correction and their processors, please refer to [link to relevant documentation]. Figures 8-13 And its related descriptions.

[0053] Step S310: Based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, determine multiple limit movement distances of the calibration component on a preset moving plane perpendicular to the optical axis of the wide-angle camera.

[0054] A wide-angle camera is a device or apparatus capable of capturing images with a wider field of view than a camera with a standard lens. For example, the field of view of a wide-angle camera can be greater than 60°. The field of view of a wide-angle camera refers to the angular range of the entire scene that the lens of the wide-angle camera can cover; the field of view determines the size of the wide-angle camera's field of view. In some embodiments, the field of view of a wide-angle camera may include a horizontal field of view and a vertical field of view.

[0055] The horizontal field of view refers to the horizontal angle between the two farthest points visible from the left to the right of the camera lens. The vertical field of view refers to the vertical angle between the two farthest points visible from the top to the bottom of the camera lens. To explain the horizontal and vertical field of view more clearly, Figure 4 These are exemplary schematic diagrams illustrating the field of view according to some embodiments of this specification. For example... Figure 4 As shown, the horizontal field of view is the angle θ between line 2 and line 3; the vertical field of view is the angle β between line 1 and line 2.

[0056] In some embodiments, the field of view of the wide-angle camera can be obtained through operator input. For example, the operator can obtain the field of view of the wide-angle camera by consulting the product specifications and then manually input it into the distortion correction system.

[0057] The dimensional parameters of a calibration component refer to the parameters used to characterize the size of the calibration component. For example, when the calibration component is a checkerboard calibration plate, the dimensional parameters of the calibration component may include the length and width of the checkerboard calibration plate. In some embodiments, the dimensional parameters of the calibration component can be obtained through operator input.

[0058] The distance between the wide-angle camera and the calibration plate refers to the straight-line distance between the optical center of the wide-angle camera lens and the calibration plate. For example, when the calibration plate is a checkerboard calibration plate, it is placed perpendicular to the optical axis of the wide-angle camera, and the distance between the wide-angle camera and the calibration plate is the distance from the optical center of the wide-angle camera lens to the checkerboard calibration plate. The optical axis of the wide-angle camera refers to the axis of the optical fiber perpendicular to the imaging plane and passing through the lens, also known as the "camera centerline." In some embodiments, the optical axis of the wide-angle camera and the calibration plate are... Figures 9-10 The Z-axis shown is parallel.

[0059] In some embodiments, the distance between the wide-angle camera and the calibration element can be measured by a measuring element (such as an infrared rangefinder). For example, the measuring element can be mounted on the wide-angle camera mount and communicatively connected to a processor to detect the distance between the wide-angle camera and the calibration element in real time and synchronize it to the processor. In some embodiments, the distance between the wide-angle camera and the calibration element can also be measured by a first sensing component (such as a resistive potentiometer) connected to the Z-axis movement unit. For more information on the Z-axis movement unit and the first sensing component, please refer to [link to relevant documentation]. Figures 9-12 And its related descriptions.

[0060] For more information on how to determine the distance between the wide-angle camera and the calibration piece, please refer to [link to relevant documentation]. Figure 6 And its related descriptions.

[0061] Since the preset moving plane is perpendicular to the optical axis of the wide-angle camera, it can be considered as an imaging plane of the wide-angle camera. In other words, after determining the distance between the calibration component and the wide-angle camera, the corresponding imaging plane is the preset moving plane. The calibration component can move on the corresponding imaging plane.

[0062] Multiple limit movement distances refer to the distances that can reflect the movement of the calibration component from its initial position to multiple edge positions within the field of view of the wide-angle camera.

[0063] The initial position is the starting position for the movement of the calibration element. In some embodiments, the initial position places a feature point of the calibration element on the optical axis of the wide-angle camera. For example, when the calibration element is a checkerboard calibration plate, a corner point of the checkerboard calibration plate may be located on the optical axis of the wide-angle camera. In some embodiments, the center point of the calibration element is located on the optical axis of the wide-angle camera when the calibration element is in the initial position. For example, when the calibration element is a checkerboard calibration plate, the center point of the checkerboard calibration plate may be located on the optical axis of the wide-angle camera. In some embodiments, the calibration element can be adjusted to an initial state in which the calibration element and the wide-angle camera have a preset positional relationship. This preset positional relationship includes the relative position of the calibration element and the optical axis, and the distance between the calibration element and the wide-angle camera. For example, when the calibration element is a checkerboard calibration plate, in the initial state, the center of the checkerboard calibration plate is located on the optical axis of the wide-angle camera, and the distance between the calibration element and the wide-angle camera is 1 meter.

[0064] Figure 5 This is an exemplary schematic diagram illustrating the image acquisition area of ​​a wide-angle camera and a calibration element according to some embodiments of this specification. Figure 5 As shown, when the calibration piece is in its initial position, the center point O of the calibration piece is located on the optical axis of the wide-angle camera.

[0065] Edge position refers to the edge of the field of view of a wide-angle camera. For example... Figure 5 As shown, the edge of the field of view can be enclosed by multiple edge lines. The edge lines are... Figure 4 The line segments Q1, -Q1, M1, and -M1 are shown in the diagram. The edge position of the calibration element within the field of view of the wide-angle camera can be understood as at least a portion of the edge of the calibration element approaching at least one edge line, or at least a portion of the edge of the calibration element coinciding with at least one edge line. The edge position of the calibration element within the field of view of the wide-angle camera can be located at the upper or lower ends of the field of view, the left or right ends of the field of view, or a diagonal position within the field of view.

[0066] In some embodiments, adjusting the position of the calibration component by adjusting the movement of the device driving calibration component includes: adjusting the device driving calibration component to translate along a first direction or its opposite direction and adjusting the device driving calibration component to translate along a second direction or its opposite direction. The first direction is perpendicular to the second direction; both the first and second directions are perpendicular to the optical axis. In some embodiments, the first direction can be... Figure 5 The positive X-axis direction shown is used to represent the second direction, which can be represented by... Figure 5 The positive Y-axis direction is shown in the diagram.

[0067] In some embodiments, the limit of movement distance can be represented by the distance between the edge of the calibrator at its initial position and the edge position of the calibrator within the field of view of the wide-angle camera.

[0068] In some embodiments, the plurality of limit movement distances include a first limit distance P1 for the calibration element to move along a first direction, a second limit distance P2 for the calibration element to move along the opposite direction of the first direction, a third limit distance P3 for the calibration element to move along a second direction, and a fourth limit distance P4 for the calibration element to move along the opposite direction of the second direction. In some embodiments, the plurality of limit movement distances of the calibration element on a preset movement plane perpendicular to the optical axis of the wide-angle camera can be represented in the form of an array, such as (P1, P2, P3, P4).

[0069] It should be understood that the movement of the calibration component from the initial position to the edge position can be the maximum distance the calibration component can move from the initial position along one of the first direction, the opposite direction of the first direction, the second direction, and the opposite direction of the second direction; or it can be the maximum distance the calibration component can move along one of the first direction or the opposite direction of the first direction, and the second direction or the opposite direction of the second direction.

[0070] In some embodiments, the processor determines multiple limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component. This includes: the processor determining, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, a first limit distance P1 for the calibration component to move along a first direction, a second limit distance P2 for moving along the opposite direction of the first direction, a third limit distance P3 for moving along a second direction, and a fourth limit distance P4 for moving along the opposite direction of the second direction on the preset movement plane perpendicular to the optical axis of the wide-angle camera.

[0071] In some embodiments, the processor can determine, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, a preset table, the first limit distance P1, the second limit distance P2, the third limit distance P3, and the fourth limit distance P4 of the calibration component moving in the first direction on a preset moving plane perpendicular to the optical axis of the wide-angle camera.

[0072] The preset table can be used to characterize the correspondence between the field of view of the wide-angle camera, the size parameters of the calibration component, the distance between the wide-angle camera and the calibration component, and multiple limit distances (P1, P2, P3, P4) of the calibration component on a preset moving plane perpendicular to the optical axis of the wide-angle camera. In some embodiments, each set of wide-angle camera field of view, calibration component size parameters, and distance between the wide-angle camera and the calibration component corresponds to a set (P1, P2, P3, P4). In some embodiments, the preset table can be constructed based on historical data.

[0073] In other embodiments, multiple limit movement distances can be determined by calculation. For further embodiments on how to determine multiple limit movement distances of the calibration element on a preset movement plane perpendicular to the optical axis of the wide-angle camera, please refer to... Figure 8 And its related descriptions.

[0074] Step S320: Based on multiple extreme movement distances, the device drives the calibration component to move to reach multiple edge positions respectively.

[0075] In some embodiments, the processor can generate movement control instructions based on multiple limit movement distances to control the adjustment device to drive the calibration member to move to multiple edge positions respectively. For example, assuming the multiple limit movement distances are (0, 0, 0, n), the processor can generate movement control instructions to drive the calibration member to move n distance units (e.g., millimeters) in the opposite direction of the second direction, thereby controlling the adjustment device to drive the calibration member to move n distance units in the opposite direction of the second direction, so that at least a portion of the edge of the calibration member approaches the edge line -Q1 or at least a portion of the edge of the calibration member coincides with the edge line -Q1. For example, assuming multiple limit movement distances are (m, 0, 0, n), the processor can generate movement control instructions to drive the calibration component to move m distance units along the first direction and n distance units in the opposite direction of the second direction. This controls the adjustment device to drive the calibration component to move m distance units along the first direction and then n distance units in the opposite direction of the second direction, so that at least a portion of the edge of the calibration component simultaneously approaches edge line M1 and edge line -Q1 or at least a portion of the edge of the calibration component simultaneously coincides with edge line M1 and edge line -Q1.

[0076] In step S330, at each edge position, the orientation of the calibration component is adjusted by adjusting the rotation of the calibration component driven by the device, and multiple shots are taken using a wide-angle camera to determine the standard orientation of the calibration component at each edge position and the first angle data of adjusting the rotation of the calibration component driven by the device under the standard orientation.

[0077] In some embodiments, adjusting the orientation of a calibration component by rotating it includes: adjusting the device to drive the calibration component to rotate about a first axis and driving the calibration component to rotate about a second axis. The first axis is perpendicular to the second axis; both the first and second axes are perpendicular to the optical axis of the wide-angle camera. For more information on the first and second axes, please refer to [link to relevant documentation]. Figure 10 And its related descriptions.

[0078] In some embodiments, the processor adjusts the orientation of the calibration member by adjusting the rotation of the device-driven calibration member, including: the processor adjusting the rotation of the device-driven calibration member about a first axis and / or driving the calibration member to rotate about a second axis.

[0079] In some embodiments, at each edge location, the processor may generate a first rotation command to control the adjustment device to drive the calibration element to rotate about a first axis and / or drive the calibration element to rotate about a second axis.

[0080] In some embodiments, adjusting the orientation of the calibration member by adjusting the rotation of the device-driven calibration member further includes: adjusting the rotation of the device-driven calibration member about a third axis. The third axis is parallel to the optical axis of the wide-angle camera. For more information on the third axis, please refer to [link to relevant documentation]. Figure 10 And its related descriptions.

[0081] In some embodiments, the processor adjusts the orientation of the calibration member by adjusting the rotation of the device-driven calibration member, and further includes: the processor adjusting the rotation of the device-driven calibration member about a third axis.

[0082] In some embodiments, the processor may also generate a second rotation command to control the adjustment device to drive the calibration element to rotate about a third axis. By automatically driving the calibration element to rotate about the third axis through the adjustment device, the attitude of the calibration element can be further adjusted, which is beneficial to obtaining a better attitude of the calibration element so that the wide-angle camera can acquire more and better quality feature points.

[0083] The standard pose is the pose of all feature points of the calibration piece that the wide-angle camera can capture when the calibration piece is at each edge position. When the calibration piece is a checkerboard calibration board, the standard pose can be the pose of all corner points of the checkerboard calibration board that the wide-angle camera can capture when the checkerboard calibration piece is at each edge position.

[0084] The first angle data is the angle at which the calibration component is rotated by the device drive when the calibration component is in a standard posture at each edge position. In some embodiments, the first angle data may include the angle at which the device drive calibration component rotates about a first axis, and / or the angle at which the device drive calibration component rotates about a second axis. In some embodiments, the first angle data may also include the angle at which the device drive calibration component rotates about a third axis.

[0085] Step S340: Determine the distortion correction parameters for the wide-angle camera based on the first angle data at each edge location.

[0086] The parameters for wide-angle camera distortion correction refer to the relevant parameters used for distortion correction calibration of a wide-angle camera. In some embodiments, the parameters for wide-angle camera distortion correction can reflect the angle of rotation of the calibration element about a first axis and / or about a second axis at various edge positions.

[0087] In some embodiments, the processor can directly determine the first angle data as the parameters for wide-angle camera distortion correction based on the first angle data at each edge location.

[0088] In some embodiments, the processor can also determine the first angle data of non-edge locations based on the first angle data at each edge location. For example, based on the initial position as the edge location, multiple coordinate points of the non-edge location are determined, and then based on the initial position, the corresponding coordinate points, the distance between the non-edge location and the edge location, and the first angle data at the edge location, the first angle data at the corresponding coordinate points is determined (for example, the closer the non-edge location is to the edge location, the smaller its angle around the first rotation axis and / or the second rotation axis). The first angle data of the non-edge location and the edge location are then used as parameters for distortion correction of the wide-angle camera.

[0089] When the calibration component is a checkerboard calibration board, the outlines of the black and white squares on the checkerboard calibration board are distributed vertically and horizontally, and form intersecting grid lines. Therefore, the corner point on the checkerboard calibration board located on the optical axis of the wide-angle camera can be used as the center point. Then, based on the first angle data of the calibration component at each edge position, multiple coordinate points at non-edge positions can be determined.

[0090] In some embodiments, the processor can further determine multiple traversal positions of the calibration member on a preset moving plane within the field of view of the wide-angle camera; reach each traversal position by adjusting the device-driven movement of the calibration member; at each traversal position, based on first angle data at each edge position, adjust the orientation of the calibration member by adjusting the device-driven rotation of the calibration member; and take multiple shots using the wide-angle camera to determine the standard orientation of the calibration member at each traversal position and second angle data for adjusting the device-driven rotation of the calibration member in the standard orientation; and determine the parameters for wide-angle camera distortion correction based on the first angle data at each edge position and the second angle data at each traversal position. For more information on how to determine the parameters for wide-angle camera distortion correction, please refer to [link to relevant documentation]. Figure 6 And its related descriptions.

[0091] In some embodiments, the processor can perform distortion correction calibration on the wide-angle camera in the medical imaging device based on the distortion correction parameters of the wide-angle camera. The wide-angle camera in the medical imaging device is used for binocular imaging ranging. Exemplary medical imaging devices may include, but are not limited to, X-ray machines.

[0092] As an example only, when a wide-angle camera is used for binocular imaging ranging, the distortion correction calibration steps for the wide-angle camera are as follows:

[0093] S1: Acquire a first image of the calibration element. The first image is an original image of the calibration element, such as an image where the center point of the calibration element is located on the optical axis of the wide-angle camera. In some embodiments, the first image of the calibration element can be acquired by capturing it with a wide-angle camera.

[0094] S2: Obtain the intrinsic parameter matrix of the wide-angle camera. The intrinsic parameter matrix of the wide-angle camera consists of parameters describing the internal properties of the camera, including focal length, principal point (optical center) coordinates, etc. In some embodiments, the intrinsic parameter matrix of the wide-angle camera can be obtained through operator input.

[0095] S3: Based on the intrinsic parameter matrix of the wide-angle camera and the distortion correction parameters of the wide-angle camera, the first image is distorted using a distortion correction algorithm. The distorted calibration component is then photographed using the wide-angle camera to obtain a second image of the distorted calibration component. The distortion correction algorithm may include functions such as `cv2.undistort`. In some embodiments, the distortion correction algorithm can be obtained by querying the OpenCV library.

[0096] S4: Obtain the mapping transformation matrix for distortion correction and stereo correction. In some embodiments, the mapping transformation matrix can be obtained through the cv2.initUndistortRectifyMap function.

[0097] S5: Based on the mapping transformation matrix, the second image is remapped to eliminate distortion.

[0098] In some embodiments of this specification, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, multiple limit movement distances of the calibration component on a preset moving plane perpendicular to the optical axis of the wide-angle camera can be accurately determined. Then, the calibration component is automatically driven by the adjustment device to perform distortion correction calibration. Compared with manual adjustment of the calibration component, which leads to inconsistent adjustment angles, is time-consuming and labor-intensive, and also results in poor quality of the acquired feature points, thus reducing calibration accuracy, and even failing to acquire feature points at the corners of the image, leading to calibration failure, the calibration component can be adjusted faster and the adjustment range is controllable. This effectively improves calibration efficiency while ensuring high calibration accuracy, which is more conducive to the distortion correction calibration of wide-angle cameras in industrial batches.

[0099] Figure 6 This is an exemplary flowchart illustrating a method for determining distortion correction parameters for a wide-angle camera according to some embodiments of this specification. In some embodiments, process 600 includes the following steps. In some embodiments, process 600 may be executed by a processor of a distortion correction system.

[0100] Step S610: Determine multiple traversal positions of the calibration component on the preset moving plane within the field of view of the wide-angle camera.

[0101] The traversal position is the position of the calibrator within the field of view of the wide-angle camera each time it stops moving on a preset moving plane. In some embodiments, multiple traversal positions of the calibrator within the field of view of the wide-angle camera on the preset moving plane can be preset by the operator.

[0102] In some embodiments, the traversal position can be represented by the coordinates of the center point of the calibrator within the field of view of the wide-angle camera on a preset movement plane. This is merely an example. Figure 5 As shown, the traversal positions can be represented as O1(x1, y1), O2(-x1, y1), O3(-x1, -y1), O4(x1, -y1), etc. Specifically, O1(x1, y1) is located in the first quadrant M1OQ1, O2(-x1, y1) is located in the second quadrant (-M1)OQ1, O3(-x1, -y1) is located in the third quadrant M1O(-Q1), and O4(x1, -y1) is located in the fourth quadrant (-M1)O(-Q1). It should be noted that only one traversal position is shown here for each quadrant of the wide-angle camera's field of view; however, in actual calibration, each quadrant can have multiple traversal positions, such as 4, 9, 12, and 16.

[0103] In some embodiments, multiple traversal positions are arranged in an array within the field of view of a wide-angle camera, with the rows of the array parallel to a first direction and the columns of the array parallel to a second direction. For example, the multiple traversal positions can form an array of 4×4, 4×6, 6×6, 6×8, 12×12, 12×16, etc.

[0104] In some embodiments, the closer the traversal position in the array is to the edge position along the first direction and its opposite direction from the initial position, the larger the rotation step size of the calibration component driven by the adjustment device. Similarly, the closer the traversal position in the array is to the edge position along the second direction and its opposite direction from the initial position, the larger the rotation step size of the calibration component driven by the adjustment device. Since distortions in wide-angle cameras (such as barrel distortion) are typically more pronounced at the edges of the images they capture, and the closer to the edge, the greater the impact of distortion on the image, it is necessary to appropriately increase the rotation step size of the calibration component to better acquire its pose, improve the quality of feature points (such as corner points) acquired by the wide-angle camera, and ensure the quantity of feature points, thereby improving calibration accuracy.

[0105] For more information on initial position and edge position, please refer to [link / reference]. Figure 3 , Figure 5 And its related descriptions.

[0106] In some embodiments of this specification, by increasing the traversal step size in areas near the edges, the distortion of the wide-angle camera in these areas can be captured more accurately. This helps to improve the quality of feature points acquired by the wide-angle camera and ensure the quantity of feature points, thereby improving the accuracy of distortion correction calibration.

[0107] In step S620, the calibration component is moved by adjusting the device to reach each traversal position. At each traversal position, based on the first angle data at each edge position, the orientation of the calibration component is adjusted by adjusting the rotation of the device to drive the calibration component. Multiple shots are taken using a wide-angle camera to determine the standard orientation of the calibration component at each traversal position and the second angle data for adjusting the rotation of the device to drive the calibration component under the standard orientation.

[0108] In some embodiments, the processor can generate traversal control instructions based on each traversal position to control the adjustment device to drive the calibration component to move to each traversal position. To more clearly illustrate the movement of the adjustment device to drive the calibration component to reach each traversal position... Figure 7 An exemplary schematic diagram of the adjustment device, calibration components, and wide-angle camera is shown. Combined with... Figure 5 , Figure 7 As shown, for example, the first traversal position is Figure 5 When O1(x1, y1) is shown, the processor can generate movement control commands for driving the calibration element 2 to move x1 distance units (e.g., millimeters) along the first direction X and y1 distance units along the second direction Y and send them to the adjustment device. When the adjustment device receives the control commands, it controls the X-axis movement unit to move x1 distance units along the first direction X and controls the Y-axis movement unit to move y1 distance units along the second direction Y, so that the center point of the calibration element 2 is located at the first traversal position O1(x1, y1).

[0109] For more information on the X-axis and Y-axis movement units, please refer to the following text (e.g. Figures 9-12 The relevant description in )

[0110] In some embodiments, the processor reaches each traversal position by adjusting the movement of a device-driven calibration element, including adjusting the device-driven calibration element to translate along a third direction or its opposite direction. The third direction is parallel to the optical axis of the wide-angle camera.

[0111] In some embodiments, whether the processor needs to drive the calibration element to translate along a third direction or its opposite direction via the adjustment device can be determined based on the imaging effect of the wide-angle camera. In some embodiments, the imaging effect of the wide-angle camera can be characterized by the ratio of the imaging area of ​​the calibration element to the area of ​​the imaging region within the imaging region corresponding to the field of view of the wide-angle camera. For example, if the ratio of the imaging area of ​​the calibration element to the area of ​​the imaging region within the imaging region corresponding to the field of view of the wide-angle camera meets a preset threshold, it indicates that the current imaging effect of the wide-angle camera meets the application requirements, and there is no need to adjust the distance between the wide-angle camera and the calibration element. As another example, if the ratio of the imaging area of ​​the calibration element to the area of ​​the imaging region within the imaging region corresponding to the field of view of the wide-angle camera does not meet the preset threshold, it indicates that the current imaging effect of the wide-angle camera does not meet the application requirements. In this case, a movement control command for driving the calibration element to translate along a third direction or its opposite direction can be generated and sent to the adjustment device. When the adjustment device receives the control command, it correspondingly controls the Z-axis movement unit to translate along a third direction or its opposite direction to adjust the distance between the wide-angle camera and the calibration element.

[0112] In some embodiments, the method for determining the distance between the wide-angle camera and the calibration element includes:

[0113] S621: Position the calibration component in its initial position. For more information on the initial position, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0114] S622: Based on the initial position, the position of the calibration element is adjusted by translating the calibration element along a third direction or its opposite direction, so that the ratio (or percentage) of the imaging area of ​​the calibration element to the area of ​​the imaging region corresponding to the field of view of the wide-angle camera is a preset threshold. The preset threshold can be determined based on historical data or actual application requirements. In some embodiments, the preset threshold range can be 15% to 20%. In some embodiments, the preset threshold range can also be 20% to 30%. In some embodiments, the preset threshold range can also be 30% to 35%. For example, the preset threshold is 25%.

[0115] S623: The distance between the adjusted calibration element and the wide-angle camera is used as the interval distance. For more information on interval distance, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0116] In some embodiments of this specification, by limiting the ratio of the imaging area of ​​the calibration component to the area of ​​the imaging region corresponding to the field of view of the wide-angle camera, the imaging effect of the wide-angle camera can be effectively guaranteed. Simultaneously, based on the ratio of the imaging area of ​​the calibration component to the area of ​​the imaging region, the distance between the wide-angle camera and the calibration component is determined, and then it is determined whether it is necessary to drive the calibration component to move in a third direction or its opposite direction via adjustment equipment. This effectively reduces calibration steps and improves calibration efficiency.

[0117] In some embodiments, the processor can adjust the orientation of the calibration member based on first angle data at each edge location by adjusting the device to drive the calibration member to rotate around a first axis and / or drive the calibration member to rotate around a second axis. As mentioned above, the closer to the edge location, the larger the rotation step size of the device to drive the calibration member to rotate around the first and / or second axes. Therefore, the processor can appropriately adjust the rotation angle of the calibration member around the first and / or second axes based on the first angle data at each edge location and the distance between the traversal location and the corresponding edge location, so that the rotation angle of the calibration member at the traversal location is smaller than the rotation angle calibrated at the corresponding edge location. The corresponding edge location can be the edge location closest to the traversal location.

[0118] In some embodiments, the processor can also adjust the orientation of the calibrator by adjusting the rotation of the device-driven calibrator about a third axis based on the first angle data at each edge location. Understandably, the angle of rotation of the calibrator about the third axis at the traversed location must also be smaller than the angle of rotation of the calibrator about the third axis at the corresponding edge location.

[0119] The second angle data refers to the angle at which the calibration component is rotated by the device when it is in the standard posture at each traversal position. For more information on the standard posture, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0120] In some embodiments, the second angle data may include adjusting the angle of rotation of the device drive calibration member about a first axis, and / or adjusting the angle of rotation of the device drive calibration member about a second axis. In some embodiments, the second angle data may further include adjusting the angle of rotation of the device drive calibration member about a third axis.

[0121] Step S630: Based on the first angle data at each edge position and the second angle data at each traversal position, determine the parameters for distortion correction of the wide-angle camera.

[0122] In some embodiments, the processor can determine the first angle data and the second angle data at each edge position as parameters for wide-angle camera distortion correction based on the first angle data at each traversal position. It should be noted that the wide-angle camera distortion correction parameters determined in this embodiment include the first angle data at each edge position and the second angle data at each traversal position, which is equivalent to determining the attitude adjustment data corresponding to each coordinate within the field of view of the wide-angle camera. In some embodiments, the processor can perform distortion correction calibration on the wide-angle camera in a medical imaging device based on the wide-angle camera distortion correction parameters determined in this embodiment. By adjusting the attitude at each coordinate within the field of view of the wide-angle camera, distortion correction processing can be performed more precisely, effectively improving calibration accuracy.

[0123] In some embodiments of this specification, the calibration component is automatically moved to various traversal positions using an adjustment device, and its orientation is adjusted by rotating the calibration component. Compared to manual adjustment, the automatic device reduces human error and ensures accurate distance and angle movements each time. Furthermore, the adjustment device can repeatedly perform the same movement and adjustment operations, ensuring high consistency in the calibration process under different times and conditions. Moreover, the automation process reduces the time required for manual adjustment of the calibration component, making the entire calibration process faster and improving calibration efficiency.

[0124] Figure 8 This is an exemplary flowchart illustrating a method for determining multiple limit travel distances according to some embodiments of this specification. In some embodiments, process 800 may include the following steps. In some embodiments, process 800 may be executed by a processor of a distortion correction system.

[0125] Step S810: Determine the horizontal field of view width based on the horizontal field of view angle and the distance between the wide-angle camera and the calibration component.

[0126] Horizontal field of view refers to the actual horizontal field of view when a wide-angle camera photographs a calibration element. In some embodiments, the processor can calculate the horizontal field of view based on the horizontal field of view and the distance between the wide-angle camera and the calibration element. For example, the horizontal field of view can be calculated using the following formula: H = 2 × d × tan(θ / 2). Where H is the horizontal field of view; d is the distance between the wide-angle camera and the calibration element; and θ is the horizontal field of view of the wide-angle camera.

[0127] For more information on the horizontal field of view and the distance between the wide-angle camera and the calibration element, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0128] Step S820: Determine the vertical field of view height based on the vertical field of view angle and the distance between the wide-angle camera and the calibration component.

[0129] Vertical field of view height refers to the actual vertical field of view when the wide-angle camera photographs the calibration element. Similarly, the processor can calculate the vertical field of view height based on the vertical field of view angle and the distance between the wide-angle camera and the calibration element. For example, the vertical field of view height can be calculated using the following formula: V = 2 × d × tan(β / 2). Where V is the vertical field of view width; d is the distance between the wide-angle camera and the calibration element; and β is the vertical field of view angle of the wide-angle camera.

[0130] For more information on the vertical field of view and the distance between the wide-angle camera and the calibration element, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0131] Step S830: Based on the horizontal field of view width and the size parameters of the calibration component, determine the first limit distance for the calibration component to move along the first direction and the second limit distance for the calibration component to move in the opposite direction of the first direction.

[0132] In some embodiments, the processor can obtain a first limit distance P1 for the calibration component to move along a first direction and a second limit distance P2 for the calibration component to move in the opposite direction of the first direction, based on the horizontal field of view width and the size parameters of the calibration component, through a first trimming process.

[0133] The first cropping process refers to the method used to correct the horizontal field of view width of a wide-angle camera. As an example only, the calculation formula involved in the first cropping process may include: P1 = P2 = (H - λ - a) / 2. Where P1 is the first limit distance the calibration element moves along the first direction; P2 is the second limit distance the calibration element moves in the opposite direction of the second direction; H is the horizontal field of view width; λ is the cropping distance at the horizontal edge; and a is the dimensional parameter of the calibration element. The cropping distance at the horizontal edge refers to the cropping width used to crop the edge of the horizontal field of view width.

[0134] Step S840: Based on the vertical field of view height and the size parameters of the calibration component, determine the third limit distance for the calibration component to move along the second direction and the fourth limit distance for the calibration component to move in the opposite direction of the second direction.

[0135] In some embodiments, the processor can obtain, through a second trimming process, a third limit distance P3 for the calibration component to move along the second direction and a fourth limit distance P4 for the calibration component to move in the opposite direction of the second direction, based on the vertical field of view height and the size parameters of the calibration component.

[0136] The second cropping process refers to the method used to correct the vertical field of view width of a wide-angle camera. As an example, the calculation formula involved in the second cropping process may include: P3 = P4 = (V - μ - a) / 2. Where P3 is the third limit distance the calibration element moves along the second direction; P4 is the fourth limit distance the calibration element moves in the opposite direction of the second direction; V is the vertical field of view width; μ is the cropping distance at the vertical edge; and a is the dimensional parameter of the calibration element. The cropping distance at the vertical edge refers to the cropping width used to crop the edge of the vertical field of view width.

[0137] It should be noted that the clipping distance λ of the horizontal edge and the clipping distance μ of the vertical edge can be the same or different, and can be determined according to the actual situation.

[0138] In some embodiments of this specification, the horizontal field of view and the vertical field of view are determined based on the field of view of the wide-angle camera and the distance between the wide-angle camera and the calibration component. Then, by combining the distance between the wide-angle camera and the calibration component and the clipping distance, the influence of the field of view edge of the wide-angle camera can be effectively eliminated through clipping processing. This allows for multiple extreme movement distances that meet the acquisition requirements, ensuring the number of corner points acquired by the wide-angle camera and guaranteeing calibration accuracy.

[0139] It should be noted that the above descriptions of processes 300, 600, and 800 are for illustrative purposes only and do not limit the scope of this specification. Those skilled in the art can make various modifications and changes to processes 300, 600, and 800 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0140] Figure 9 This is a schematic diagram of the structure of a system for distortion correction of a wide-angle camera, as shown in some embodiments of this specification. Figure 1 ; Figure 10 This is a schematic diagram of a system for distortion correction of a wide-angle camera, as shown in some embodiments of this specification.

[0141] This specification provides a system for distortion correction in wide-angle cameras (referred to as the "distortion correction system") through some embodiments. Figures 9-10 As shown, the distortion correction system 100 may include an adjustment device 1, a calibration component 2, and a processor (not shown in the figure), with the processor communicatively connected to the adjustment device 1. Exemplary communication connection methods may include, but are not limited to, WIFI, Bluetooth, and fiber optic connections.

[0142] The adjustment device 1 is a device or apparatus used by the distortion correction system 100 to drive the calibration member to move or rotate. In some embodiments, the adjustment device 1 can be used to drive the calibration member 2 to move and adjust the position of the calibration member 2. In some embodiments, the adjustment device can also be used to drive the calibration member 2 to rotate and adjust the orientation of the calibration member 2.

[0143] Calibration element 2 refers to a reference object used in the measurement, calibration, or standardization process. In some embodiments, calibration element 2 may be a checkerboard calibration plate.

[0144] In some embodiments, the calibration member 2 may be fixedly connected to the adjustment device 1 and moved or rotated by the adjustment device 1. For example, the calibration member may be moved along a first direction and its opposite direction under the action of the adjustment device.

[0145] The processor can process data and / or information obtained from other system components. Based on this data, information, and / or processing results, the processor can execute program instructions to perform one or more functions described in this specification. In some embodiments, the processor may include one or more sub-processing devices (e.g., a single-core processing device or a multi-core multi-chip processing device). By way of example only, the processor may include a central processing unit (CPU), a controller, a microcontroller unit, a microprocessor, or any combination thereof.

[0146] In some embodiments, the processor may include a calibration component control module and a data analysis module. The calibration component control module is a module for controlling the movement of the calibration component. The data analysis module is a module for processing data and / or information obtained from other system components.

[0147] In some embodiments, the calibration component control module can be configured to: drive the calibration component to move to adjust the position of the calibration component; and drive the calibration component to rotate to adjust the attitude of the calibration component.

[0148] In some embodiments, the data analysis module can be configured to: determine multiple limit movement distances of the calibration member on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration member, and the distance between the wide-angle camera and the calibration member, wherein the multiple limit movement distances reflect the movement distances of the calibration member from its initial position to multiple edge positions within the field of view of the wide-angle camera; based on the multiple limit movement distances, adjust the device to drive the calibration member to move to reach the multiple edge positions respectively; at each edge position, adjust the orientation of the calibration member by adjusting the device to drive the calibration member to rotate, and take multiple shots with the wide-angle camera to determine the standard orientation of the calibration member at each edge position and the first angle data of adjusting the device to drive the calibration member to rotate under the standard orientation; and determine the parameters for wide-angle camera distortion correction based on the first angle data at each edge position.

[0149] It should be noted that the above description of the processor and its modules is for convenience only and should not be construed as limiting this specification to the embodiments described. It is understood that those skilled in the art, after understanding the principles of the system, may arbitrarily combine the various modules or construct subsystems connected to other modules without departing from these principles. In some embodiments, the calibration control module and data analysis module described above may be different modules within a single processor, or a single module may implement the functions of two or more of the aforementioned modules. For example, the modules may share a single storage module, or each module may have its own separate storage module. Such variations are all within the scope of this specification.

[0150] For more information on distortion correction systems, please refer to [link / reference]. Figures 11-15 And its related descriptions.

[0151] In some embodiments, such as Figures 9-10 As shown, the adjustment device 1 includes a moving component 11, a rotating component 12 and a wide-angle camera mount 13. The calibration component 2 is disposed on the rotating component 12. The rotating component 12 is connected to the moving component 11. The moving component 11 and the wide-angle camera mount 13 are spaced apart.

[0152] The moving component 11 is a part of the adjusting device 1 used to drive the calibration member 2 to move. In some embodiments, the moving component 11 may have at least two degrees of freedom of translation. Preferably, the moving component 11 may have three degrees of freedom of translation. In some embodiments, the moving component 11 is capable of driving the calibration member 2 to translate along a first direction or its opposite, along a second direction or its opposite, and along a third direction or its opposite.

[0153] In some embodiments, the first direction can be used Figures 9-10The positive X-axis direction shown is used to represent the second direction; the second direction can be represented by... Figures 9-10 The positive Y-axis is shown in the diagram; the third direction can be represented by... Figures 9-10 The positive Z-axis direction is shown in the diagram.

[0154] For more information on mobile components, please see the following text (e.g. Figures 11-12 The relevant description in )

[0155] The rotating assembly 12 is a component of the adjusting device 1 used to drive the calibration member 2 to rotate. In some embodiments, the rotating assembly 12 may have at least two degrees of freedom of rotation. Preferably, the rotating assembly 12 may have three degrees of freedom of rotation. In some embodiments, the rotating assembly 12 is capable of driving the calibration member 2 to rotate about a first axis, a second axis, and a third axis, wherein the first axis, the second axis, and the third axis are orthogonal to each other. More information about the rotating assembly can be found later (e.g., ...). Figures 13-15 The relevant description in )

[0156] The wide-angle camera mount 13 is a component of the adjustment device 1 used to mount the wide-angle camera 200. The wide-angle camera mount 13 can be designed in various structural shapes, including but not limited to L-shapes. In some embodiments, such as... Figures 9-10 As shown, the wide-angle camera mount 13 can be mounted on the base plate 14 by means of threaded connection, snap-fit ​​connection, etc.

[0157] In some embodiments, the wide-angle camera mount 13 is provided with camera mounting holes for mounting the wide-angle camera 200. It should be noted that, in the initial state, the lens of the wide-angle camera 200 should be parallel to the plane of the calibration member 2, for example, perpendicular to the base plate 14.

[0158] In some embodiments, the wide-angle camera 200 can be used for binocular imaging ranging. For more information on binocular imaging ranging, please refer to the relevant description above.

[0159] In some embodiments, such as Figures 9-10 As shown, the moving component 11 may include an X-axis moving unit 111, a Y-axis moving unit 112, and a Z-axis moving unit 113. The X-axis moving unit 111 can be used to drive the calibration element 2 to translate along a first direction; the Y-axis moving unit 112 can be used to drive the calibration element 2 to translate along a second direction; and the Z-axis moving unit 113 can be used to drive the calibration element 2 to translate along a third direction.

[0160] In some embodiments, the Z-axis moving unit 113 is disposed on the base plate 14 along a third direction, the X-axis moving unit 111 is disposed on the Z-axis moving unit 113 along a first direction, and the Y-axis moving unit 112 is disposed on the X-axis moving unit 111 along a second direction. The X-axis moving unit 111 can be fixedly connected to the output end of the Z-axis moving unit 113, and the Y-axis moving unit 112 can be fixedly connected to the output end of the X-axis moving unit 111. Exemplary fixed connection methods may include, but are not limited to, threaded connections, snap-fit ​​connections, welding, etc.

[0161] The base plate 14 refers to the component used for fixing and installing the adjustment device 1. The base plate 14 can be flat or similar in shape. In some embodiments, the Z-axis moving unit 113 can be fixed to the base plate 14 by fasteners such as screws.

[0162] Figure 11 This is a schematic diagram of the structure of a moving component according to some embodiments of this specification.

[0163] In some embodiments, such as Figure 11 As shown, the moving component 11 can be composed of a motor 1101 and a transmission unit 1102, that is, the X-axis moving unit 111, the Y-axis moving unit 112, and the Z-axis moving unit 113 are all composed of a motor 1101 and a transmission unit 1102. The output end of the motor 1101 can be fixedly connected to the output end of the transmission unit 1102 to drive the transmission unit 1102 to perform translational movement.

[0164] In some embodiments, the transmission unit 1102 may include a fixing member 11021, a ball screw 11022, and a connecting member 11023. Both the motor 1101 and the ball screw 11022 are fixedly connected to the fixing member 11021. The output end of the motor 1101 is fixedly connected to one end of the screw of the ball screw 11022 and can drive the screw to rotate on the fixing member 11021. The connecting member 11023 is fixedly connected to the nut of the ball screw 11022. When the screw rotates, the nut located on the screw can move along the axial direction of the screw (i.e., the third direction or its opposite direction), thereby driving the connecting member 11023 to move. Taking only the Z-axis movement unit 113 as an example, as... Figure 11 As shown, the fixing member 11021 is mounted on the base plate 14 along the third direction. The output end of the motor 1101 is connected to one end of the screw of the ball screw 11022. The nut of the ball screw 11022 is connected to the fixing member 11021 of the X-axis moving unit 111 through the connecting member 11023. When the motor 1101 is working, the motor 1101 rotates to drive the screw to rotate, thereby causing the nut located on the screw to move along the third direction or its opposite direction, and thus causing the X-axis moving unit 111 to translate along the third direction or its opposite direction.

[0165] It should be understood that for each transmission unit 1102 in the X-axis moving unit 111, Y-axis moving unit 112 and Z-axis moving unit 113, the structural shape and arrangement of its connecting member 11023 may be the same or different, and can be determined according to the actual situation.

[0166] Figure 12 This is a schematic diagram of the structure of the Y-axis moving unit according to some embodiments of this specification.

[0167] In some embodiments, such as Figures 9-10 As shown, the rotating component 12 can be disposed on the Y-axis moving unit to realize the connection between the rotating component 12 and the moving component 11. In some embodiments, such as Figure 12 As shown, for the Y-axis moving unit 113, the connector 11023 may include a connecting block 110231 and a connecting plate 110232. The connecting block 110231 is mounted on the nut of the ball screw 11022 and is used to connect the nut and the connecting plate 110232; the connecting plate 110232 is mounted on the connecting block 110231 and is used to mount the rotating assembly 12. It can be understood that the connecting block 110231 and the connecting plate 110232 can be separate structures or integrally formed structures (i.e., the connector 11023 is a single, integral structure).

[0168] In some embodiments, such as Figures 11-12 As shown, the moving component 11 is provided with a first sensing component 1103, which is configured to acquire the distance of the calibration component 2 translated along a first direction or its opposite direction, the distance of the calibration component 2 translated along a second direction or its opposite direction, and the distance of the calibration component 2 translated along a third direction or its opposite direction.

[0169] The first sensing component 1103 is a part of the adjustment device 1 used to detect the translation distance of the calibration element 2. An exemplary first sensing component 1103 may include, but is not limited to, a linear encoder, a resistive potentiometer, or a drawstring box.

[0170] In some embodiments, the X-axis moving unit 111, the Y-axis moving unit 112, and the Z-axis moving unit 113 are all provided with a first sensing component 1103. The first sensing component 1103 can be a resistance potentiometer, which includes a resistor 11031 and a slider 11032. The resistor 11031 is disposed on one side of the transmission part 1102 along the axial direction (or the axial direction of the screw) of the transmission part 1102. The slider 11032 is slidably connected to the resistor 11031 and fixedly connected to the connecting member 11023 of the transmission part 1102. The slider 11032 can be fixedly connected to the connecting member 11023 via a structure such as an L-shaped connecting member 1104. When the connector 11023 moves axially along the transmission part 1102, the slider 11032 can slide on the resistor 11031 to change the resistance value in the measuring circuit, thereby obtaining the distance that the connector 11023 moves axially along the transmission part 1102, and then the distance that the calibrator 2 translates along the first direction or its opposite direction, the distance that translates along the second direction or its opposite direction, and the distance that translates along the third direction or its opposite direction can be obtained.

[0171] Figure 13 This is a schematic diagram of the structure of the rotating assembly shown in some embodiments of this specification; Figure 14 This is a cross-sectional view of the rotating assembly shown in some embodiments of this specification.

[0172] In some embodiments, such as Figure 10 , Figures 13-14 As shown, the rotating assembly 12 may include an X-axis rotating unit 121, a Y-axis rotating unit 122, and a Z-axis rotating unit 123. The X-axis rotating unit 121 can drive the calibration element 2 to rotate around a first axis; the Y-axis rotating unit 122 can drive the calibration element 2 to rotate around a second axis; and the Z-axis rotating unit 123 can drive the calibration element 2 to rotate around a third axis.

[0173] Here, the first axis of rotation refers to the axis around which the X-axis unit 121 rotates. In some embodiments, the extending direction of the first axis of rotation is... Figure 10 The X-axis shown is parallel to the direction of rotation. The second axis of rotation refers to the axis around which the Y-axis rotation unit 122 rotates. In some embodiments, the extension direction of the second axis of rotation is parallel to the direction of rotation of the Y-axis rotation unit 122. Figure 10 The Y-axis shown is parallel to the direction of rotation. The third axis of rotation refers to the axis around which the Z-axis rotation unit 123 rotates. In some embodiments, the extension direction of the third axis is parallel to the direction of rotation of the Z-axis rotation unit 123. Figure 10 The Z-axis shown is parallel.

[0174] In some embodiments, the Y-axis rotation unit 122 is disposed on the moving assembly 11 (such as the connector 11023) along a second direction, the X-axis rotation unit 121 is disposed on the Y-axis rotation unit 122 along a first direction, and the Z-axis rotation unit 123 is disposed on the X-axis rotation unit 121 along a third direction, and the Z-axis rotation unit 123 is connected to the calibration member 2. The output ends of the X-axis rotation unit 122 and the Y-axis rotation unit 121 are fixedly connected, and the output end of the Z-axis rotation unit 123 is fixedly connected to the output end of the X-axis rotation unit 122.

[0175] In some embodiments, such as Figures 13-14 As shown, the Y-axis rotation unit 122 may include a Y-axis rotation motor 1221 and a gear transmission unit 1222. The gear transmission unit 1222 includes a first gear 12221 and a second gear 12222. The output end of the Y-axis rotation motor 1221 is fixedly connected to the second gear 12222. Both the first gear 12221 and the second gear 12222 are mounted on the connector 11023 (such as a connecting plate 110232) of the Y-axis moving unit 113. One end of both the first gear 12221 and the second gear 12222 are rotatably connected to the connecting plate 110232 via bearings 1223, and one end of the second gear 12222 is fixedly connected to the output end of the Y-axis rotation motor 1221. The other ends of the second gear 12222 and the first gear 12221 mesh with each other. When the Y-axis rotation motor 1221 drives the second gear 12222 to rotate, it can drive the first gear 12221 to rotate around a first axis. In some embodiments, the structural dimensions (e.g., diameter) of the first gear 12221 may be larger than the structural dimensions of the second gear 12222.

[0176] In some embodiments, such as Figures 13-14 As shown, the X-axis rotation unit 121 may include an X-axis rotation motor 1211, an X-axis coupling 1212, an X-axis rotation shaft 1213, and an X-axis rotation seat 1214. The X-axis rotation motor 1211 and the X-axis rotation shaft 1213 are connected through the X-axis coupling 1212, and the X-axis rotation seat 1214 is fixed on the X-axis rotation shaft 1213.

[0177] In some embodiments, the X-axis rotation unit 121 can be fixedly connected to the Y-axis rotation unit 122 via a first bearing housing 1215. For example... Figure 13As shown, there are two first bearing seats 1215. These two first bearing seats 1215 are spaced apart along a first direction at the end of the first gear 12221 of the Y-axis rotating unit 122 away from the Z-axis moving unit 113, secured by fasteners such as screws. One end of the X-axis rotating shaft 1213 passes through bearing mounting holes located on the first bearing seats 1215 and is rotatably connected to the two first bearing seats 1215 via bearings. An X-axis rotating seat 1214 is positioned between the two first bearing seats 1215 and is used to mount the Z-axis rotating unit 123.

[0178] Figure 15 This is a structural schematic diagram of the X-axis rotary seat according to some embodiments of this specification.

[0179] In some embodiments, the portion of the X-axis rotating shaft 1213 located between the two first bearing seats 1215 is provided with a protrusion 12131, which extends along a first direction on the circumferential side of the X-axis rotating shaft 1213. A corresponding groove is provided in the through hole 12141 of the X-axis rotating seat 1214 (see...). Figure 15 When the X-axis rotary seat 1214 is fitted onto the X-axis rotating shaft 1213, the protrusion 12131 engages with the groove to prevent the X-axis rotary seat 1214 from rotating relative to the X-axis rotating shaft 1213 around the first axis. Figure 15 As shown, the end of the X-axis rotary seat 1214 away from the Z-axis moving unit 113 can be flat to facilitate the installation of the Z-axis rotary unit 123.

[0180] In some embodiments, such as Figure 13 As shown, the X-axis rotation unit 121 also includes a first support member 1216. One end of the first support member 1216 is fixedly connected to the end of the first gear 12221 of the Y-axis rotation unit 122 away from the Z-axis moving unit 113. The other end of the first support member 1216 is disposed between the X-axis rotation motor 1211 and the coupling 1212, and is rotatably connected to the output shaft of the X-axis rotation motor 1211. The first support member 1216 can be designed in various structural shapes, including but not limited to L-shapes. By setting the first support member 1216, the X-axis rotation motor 1211 is further supported, which can further improve the stability of the X-axis rotation unit 121 during rotation, thereby ensuring the stability of the adjustment device 1 during operation.

[0181] In some embodiments, such as Figure 13 As shown, the Z-axis rotation unit 123 may include a Z-axis rotation motor 1231, a Z-axis coupling 1232 and a Z-axis rotation shaft 1233, with the Z-axis rotation motor 1231 and the Z-axis rotation shaft 1233 connected by the Z-axis coupling 1232.

[0182] In some embodiments, the Z-axis rotation unit 123 can be fixedly connected to the X-axis rotation unit 121 via a second bearing housing 1234. For example... Figure 13 As shown, the second bearing housing 1234 can be mounted on the X-axis rotating seat 1214 of the X-axis rotating unit 121 by fasteners such as screws. One end of the Z-axis rotating shaft 1233 passes through the bearing mounting hole of the second bearing housing 1234 and is rotatably connected to the second bearing housing 1234 through the bearing.

[0183] In some embodiments, such as Figure 13 As shown, the Z-axis rotation unit 123 also includes a second support member 1235. One end of the second support member 1235 is fixedly connected to the X-axis rotary seat 1214, and the other end of the second support member 1235 is rotatably connected to the output shaft of the Z-axis rotation motor 1231, which is located between the Z-axis rotation motor 1231 and the Z-axis coupling 1232. Similarly, the second support member 1235 can also be designed in various structural shapes such as L-shape. By setting the second support member 1235, the Z-axis rotation motor 1231 is further supported, which can further improve the stability of the Z-axis rotation unit 123 during rotation, thereby ensuring the stability of the adjustment device 1 during operation.

[0184] It should be noted that in the rotating assembly 12, when the two components are connected by a bearing, a flexible retaining ring can be used to ensure stability during rotation. This is just an example. Figure 14 As shown, an elastic retaining ring 1224 can be provided at the connection between the first gear 12221 and the connecting plate 110232. The elastic retaining ring 1224 can be provided at the connection of the connecting plate 110232 near the moving component 11 to limit the axial movement of the first gear 12221, thereby ensuring the stability of the Y-axis rotating unit 122 when rotating.

[0185] In some embodiments, a calibration plate 12331 may be provided at one end of the Z-axis rotation axis 1233 near the wide-angle camera mount 13, and the calibration plate 12331 is perpendicular to the base plate 14. In some embodiments, the calibration component 2 may be mounted on the calibration plate 12331 by means of bonding, snap-fitting, or other methods.

[0186] It should be noted that calibration component 2 can also adopt any other feasible structural form, and this specification does not limit it.

[0187] In some embodiments, the rotating assembly 12 is provided with a second sensing assembly (not shown in the figure), which is configured to acquire the angle of rotation of the calibrator 2 about a first axis, the angle of rotation about a second axis, and the angle of rotation about a third axis.

[0188] The second sensing component is a part of the adjustment device 1 used to detect the rotation angle of the calibration component 2. For example, the second sensing component may include, but is not limited to, an absolute encoder, an angle meter, etc.

[0189] In some embodiments, the X-axis rotation unit 121, the Y-axis rotation unit 122, and the Z-axis rotation unit 123 are all provided with a second sensing component. In some embodiments, the second sensing component may be an absolute encoder, integrated into the rotary motor of each rotation unit, to obtain the angle of rotation of the calibration element 2 about the first rotation axis, the angle of rotation about the second rotation axis, and the angle of rotation about the third rotation axis.

[0190] It should be noted that the above description of the structure of the adjustment device 1 (such as the moving component or the rotating component) is only an example. The adjustment device can also achieve the function of driving the calibration component to move and rotate through any other feasible structural form. For example, the adjustment device 1 may include a robotic arm, etc.

[0191] In some embodiments described in this specification, the adjustment device employs a moving component, a rotating component, and a wide-angle camera mount. A calibration component is mounted on the rotating component, which is connected to the moving component. The moving component and the wide-angle camera mount are spaced apart. Through the combined use of the moving and rotating components, the calibration component can be quickly moved in multiple directions or rotated around multiple axes, making control simple and convenient. Furthermore, both the moving and rotating components are equipped with sensors to detect and monitor the movement of the calibration component, thereby effectively improving the operating accuracy of the adjustment device.

[0192] The specific implementation method is as follows:

[0193] The Y-axis rotation unit comprises a Y-axis rotation motor, a gear transmission unit, and a connecting component. The Y-axis rotation motor has a built-in absolute encoder (i.e., a second sensing component) to locate the position of the calibration component rotating around the Y-axis. The Y-axis rotation motor is fixed below the connecting component, and the second gear of the gear transmission unit is fixed at the output end of the Y-axis rotation motor and meshes with the first gear of the gear transmission unit for transmission. The first gear of the gear transmission unit is fixed above the connecting component via a rotary bearing and can rotate arbitrarily around the Y-axis. One end of the first gear of the gear transmission unit has involute teeth, and the other end is a smooth shaft inserted into the rotary bearing, with an elastic retaining ring restricting the axial movement of the first gear of the gear transmission unit.

[0194] The connector is fixed to the slider of the Y-axis ball screw. When the Y-axis rotary motor rotates, it drives the second gear to rotate, which in turn drives the first gear of the pulley gear transmission unit to rotate, thereby driving the calibration component to rotate around the Y-axis.

[0195] The X-axis rotation unit comprises an X-axis rotation motor, bearing housings, an X-axis rotation shaft, and an X-axis rotation base. The X-axis rotation motor has a built-in absolute encoder to locate the position of the calibration component rotating around the X-axis. The X-axis rotation motor is fixed above the first gear of the gear transmission unit by a fixing component. Two bearing housings are fixed above the first gear of the gear transmission unit, and the X-axis rotation base is located between the bearing housings. The X-axis rotation base has a hub-shaped circular hole in the center. The X-axis rotation shaft passes through the hub-shaped circular hole and achieves synchronous rotation between the X-axis rotation shaft and the X-axis rotation base via a flat key. The X-axis rotation shaft is stably supported by the bearing housings. The X-axis rotation motor is connected to the X-axis rotation shaft via an X-axis coupling, which reduces the machining and assembly requirements for the coaxiality of the X-axis rotation shaft and the X-axis motor. When the X-axis rotation motor rotates, it directly drives the X-axis rotation shaft to rotate, which in turn drives the X-axis rotation base to rotate around the X-axis, thereby achieving stepless rotation of the calibration component around the X-axis.

[0196] The calibration component is a square (side length a) checkerboard calibration plate with z corner points. The calibration component is then glued to a calibration fixing plate with a rectangular feature at one end, attached to the Z-axis rotation axis. The wide-angle camera is fixed to a wide-angle camera mount.

[0197] The following methods are used for distortion correction in wide-angle cameras:

[0198] S1: Initial state, the calibration element is located in the center of the wide-angle camera's imaging area. Based on the wide-angle camera's field of view and the size of the calibration element, the Z-axis motor unit is adjusted to ensure the calibration element is fully imaged within the wide-angle camera's imaging area.

[0199] For example, the field of view of a wide-angle camera can be calculated using the camera's parameters, such as the horizontal and vertical field of view, and the distance between the calibration device and the wide-angle camera. The field of view V and H can be initially calculated using the following formulas, and then the distance d between the calibration device and the wide-angle camera can be determined.

[0200] V = 2 × d × tan(β / 2);

[0201] Where V is the vertical field of view width; d is the distance between the wide-angle camera and the calibration component; and β is the vertical field of view angle of the wide-angle camera.

[0202] H = 2 × d × tan(θ / 2);

[0203] Where H is the horizontal field of view width; d is the distance between the wide-angle camera and the calibration component; and θ is the horizontal field of view angle of the wide-angle camera.

[0204] The position information of the Z-axis electric unit can be obtained through the Z-axis resistive potentiometer (i.e., the first sensing component).

[0205] S2: Determine the travel limits P1 and Q1 of the XY axis electric unit based on the calculated field of view of the wide-angle camera and the known side length of the calibration component.

[0206] For example, wide-angle camera distortion correction calibration algorithms typically crop the image edges. In this embodiment, the cropping edge is set to 10mm, i.e., P1 = (H - 20 - a) / 2, Q1 = (V - 20 - a) / 2.

[0207] S3: The wide-angle camera captures the calibration component located at the origin and records the number of corner points z. Within the first quadrant, the X / Y axis electric unit moves the calibration component, and within the limit area diagonally opposite the origin, the X / Y / Z axis rotation unit is adjusted to obtain a calibration component with a better posture and capture the number of corner points z. The absolute encoder values ​​of the X / Y / Z axis rotation unit motors are read, which are n1, n2, and n3, respectively.

[0208] For example, combining Figure 1 Barrel distortion and Figure 5 Within the Q1OM1 quadrant, the X-axis and Y-axis motor units are controlled to move the calibration component to the limiting area diagonally opposite the origin of the coordinate system. The X-axis, Y-axis, and Z-axis rotation units are also controlled to flip and rotate the calibration component, facilitating corner point acquisition by the wide-angle camera (number of points: z). Furthermore, within the limiting area diagonally opposite the origin of the coordinate system in the Q1OM1 quadrant, the upper right corner of the calibration component is concave in the image. Therefore, the Y-axis and X-axis rotation units are controlled to rotate the calibration component clockwise. Additionally, barrel distortion is a non-linear distortion, requiring fine-tuning of the Z-axis rotation unit to rotate the calibration component. Finally, a mature calibration method, such as the Zhang Zhengyou calibration method, is used to read the corner points of the calibration component. The absolute encoders of the X / Y / Z-axis rotation unit motors record the orientation position of the calibration component within the limiting area diagonally opposite the origin of the coordinate system in the Q1OM1 quadrant. The absolute encoder values ​​are n1, n2, and n3, respectively.

[0209] S4: Control the X / Y axis electric unit to move the calibration component traverses the XOY coordinate plane. The traversal travel limits are M1, -M1, Q1, and -Q1, respectively. The calibration component is rotated and flipped by the X / Y / Z axis rotation unit. The wide-angle camera collects the corner points of the calibration component, and the number is always z.

[0210] For example, the absolute encoder values ​​n1, n2, and n3 obtained through step S3 are used to control the movement of the X / Y axis electric unit. The X / Y / Z axis rotary units rotate and flip the calibration components with variable rotational steps. When they reach the limit area corresponding to the diagonal of the origin O in each quadrant, the absolute encoder values ​​of the X / Y / Z axis rotary motors of the X / Y / Z axis rotary units are n1, n2, and n3, respectively. The difference lies in the following: in quadrant Q1OM1, the Y-axis and X-axis rotary units rotate clockwise; in quadrant Q1O(-M1), the Y-axis rotary unit rotates counterclockwise, and the X-axis rotary unit rotates clockwise; in quadrant (-Q)1O(M1), the Y-axis rotary unit rotates clockwise, and the X-axis rotary unit rotates counterclockwise; in quadrant (-Q)1O(-M1), the Y-axis rotary unit rotates counterclockwise, and the X-axis rotary unit rotates counterclockwise; in all quadrant areas, the Z-axis rotary unit only requires slight rotation and fine-tuning. Furthermore, Zhang Zhengyou's calibration method typically requires at least 15 images of calibration components at different locations.

[0211] When controlling the X / Y axis electric unit to move the calibration component, the rotation step size of the X / Y / Z axis rotary unit is adjusted by the real-time position of the X / Y axis resistive potentiometer. The closer to the limit, the greater the stroke distortion, and the larger the rotation step size of the X / Y / Z axis rotary unit. This allows for better acquisition of the calibration component's attitude, improves the quality of corner points acquired by the wide-angle camera, ensures the number of corner points z, and thus improves calibration accuracy.

[0212] S5: Control the X / Y axis electric unit and the X / Y / Z axis rotation unit to translate, rotate and flip the calibration part back to the coordinate origin area, and the corner point acquisition ends.

[0213] In some embodiments of this specification, the distortion correction system employs an adjustment device, a calibration component, and a processor. The processor is communicatively connected to the adjustment device and can drive the calibration component to move or rotate by driving the adjustment device, thereby automatically adjusting the position or orientation of the calibration component. This method saves time and effort. Furthermore, the adjustment device is also equipped with a sensing component that can monitor the movement process of the calibration component in real time and feed it back to the processor. The processor can then make timely corrections or adjustments based on the feedback data, effectively ensuring calibration accuracy. In addition, the overall system structure is relatively simple and easy to implement, showing good application prospects.

[0214] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

Claims

1. A method for distortion correction in wide-angle cameras, characterized in that, Using an adjustment device and a calibration element, the adjustment device is configured to: drive the calibration element to move to adjust the position of the calibration element, and drive the calibration element to rotate to adjust the attitude of the calibration element; The method includes the following steps: Based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, a plurality of limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera are determined; the plurality of limit movement distances reflect the distances of the calibration component from its initial position to multiple edge positions within the field of view of the wide-angle camera. Based on the multiple extreme movement distances, the calibration component is driven to move by the adjustment device to reach the multiple edge positions respectively; At each of the stated edge locations, the orientation of the calibration element is adjusted by rotating it through the adjustment device, and multiple images are taken using the wide-angle camera to determine the standard orientation of the calibration element at each of the stated edge locations and the first angle data of the rotation of the calibration element driven by the adjustment device under the standard orientation; and Based on the first angle data at each of the said edge locations, the parameters for distortion correction of the wide-angle camera are determined.

2. The method for distortion correction in a wide-angle camera as described in claim 1, characterized in that, The step of determining the distortion correction parameters for the wide-angle camera based on the first angle data at each of the aforementioned edge locations includes: Determine multiple traversal positions of the calibration element on the preset moving plane within the field of view of the wide-angle camera; The calibration component is moved to each of the traversal positions by the adjustment device. At each traversal position, based on the first angle data at each of the edge positions, the calibration component's attitude is adjusted by rotating it through the adjustment device. Multiple shots are taken using the wide-angle camera to determine the standard attitude of the calibration component at each traversal position and the second angle data of the rotation of the calibration component by the adjustment device under the standard attitude. Based on the first angle data at each of the edge positions and the second angle data at each of the traversed positions, the distortion correction parameters of the wide-angle camera are determined.

3. The method for distortion correction in a wide-angle camera as described in claim 2, characterized in that, When the calibration element is in the initial position, the center point of the calibration element is located on the optical axis of the wide-angle camera; The method of driving the calibration element to move and adjusting the position of the calibration element includes: The calibration element is driven to translate along a first direction or its opposite direction, and the calibration element is driven to translate along a second direction or its opposite direction; the first direction is perpendicular to the second direction; both the first direction and the second direction are perpendicular to the optical axis; The method, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, determines multiple limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera, including: Based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, the following limits are determined on a preset moving plane perpendicular to the optical axis of the wide-angle camera: a first limit distance for the calibration component to move along the first direction, a second limit distance for it to move along the opposite direction of the first direction, a third limit distance for it to move along the second direction, and a fourth limit distance for it to move along the opposite direction of the second direction.

4. The method for distortion correction in a wide-angle camera as described in claim 3, characterized in that, The field of view includes a horizontal field of view and a vertical field of view; The method of determining multiple limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera, based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, further includes: The horizontal field of view width is determined based on the horizontal field of view angle and the distance between the wide-angle camera and the calibration component. The vertical field of view height is determined based on the vertical field of view angle and the distance between the wide-angle camera and the calibration component; Based on the horizontal field of view width and the size parameters of the calibration component, determine the first limit distance for the calibration component to move along the first direction and the second limit distance for the calibration component to move in the opposite direction of the first direction; and Based on the vertical field of view height and the size parameters of the calibration component, the third limit distance for the calibration component to move along the second direction and the fourth limit distance for the calibration component to move in the opposite direction of the second direction are determined.

5. The method for distortion correction in a wide-angle camera as described in claim 3, characterized in that, The plurality of traversal positions form an array within the field of view of the wide-angle camera, wherein the rows of the array are parallel to the first direction and the columns of the array are parallel to the second direction; The closer the traversal position in the array is to the edge position from the initial position along the first direction or its opposite direction, the larger the rotation step size of the adjustment device driving the calibration element to rotate; The closer the traversal position in the array is to the edge position from the initial position along the second direction and its opposite direction, the larger the rotation step size of the adjustment device driving the calibration element to rotate.

6. The method for distortion correction in a wide-angle camera as described in claim 3, characterized in that, The process of moving the calibration component to reach each of the traversed positions via the adjustment device includes: The calibration element is driven to translate along a third direction or its opposite direction; the third direction is parallel to the optical axis of the wide-angle camera. The method for determining the distance between the wide-angle camera and the calibration component includes: Position the calibration element in its initial position; Based on the initial position, the position of the calibration element is adjusted by translating the calibration element along the third direction or its opposite direction using the adjustment device, so that the ratio of the imaging area of ​​the calibration element to the area of ​​the imaging region corresponding to the field of view of the wide-angle camera is a preset threshold; and The distance between the adjusted calibration component and the wide-angle camera is taken as the interval distance.

7. The method for distortion correction of a wide-angle camera as described in any one of claims 1-6, characterized in that, The method of driving the calibration component to rotate and adjusting the attitude of the calibration component includes: The calibration element is driven to rotate about a first axis and about a second axis; the first axis is perpendicular to the second axis; both the first axis and the second axis are perpendicular to the optical axis. The method of adjusting the attitude of the calibration component by driving the calibration component to rotate through the adjustment device includes: The calibration element is driven to rotate around the first rotating shaft and / or driven to rotate around the second rotating shaft by the adjustment device; The first angle data and the second angle data include: the angle at which the adjustment device drives the calibration element to rotate along the first axis, and / or the angle at which the adjustment device drives the calibration element to rotate around the second axis.

8. The method for distortion correction in a wide-angle camera as described in claim 7, characterized in that, The method of driving the calibration component to rotate and adjusting the attitude of the calibration component further includes: The calibration component is driven to rotate about a third axis; the third axis is parallel to the optical axis of the wide-angle camera. The method of adjusting the attitude of the calibration component by driving the calibration component to rotate through the adjustment device further includes: The adjustment device drives the calibration component to rotate around the third axis. The first angle data includes the angle by which the adjustment device drives the calibration component to rotate around the third axis.

9. The method for distortion correction in a wide-angle camera as described in claim 1, characterized in that, The method further includes: Based on the distortion correction parameters of the wide-angle camera, distortion correction calibration is performed on the wide-angle camera in the medical imaging equipment; the wide-angle camera in the medical imaging equipment is used for binocular imaging ranging.

10. A system for distortion correction in wide-angle cameras, characterized in that, The system includes an adjustment device, a calibration component, and a processor, wherein the processor is communicatively connected to the adjustment device. The processor includes a calibration control module and a data analysis module; wherein... The calibration component control module is configured as follows: The position of the calibration element is adjusted by driving the calibration element to move; and The orientation of the calibration component is adjusted by driving the calibration component to rotate; The data analysis module is configured as follows: Based on the field of view of the wide-angle camera, the size parameters of the calibration component, and the distance between the wide-angle camera and the calibration component, a number of limit movement distances of the calibration component on a preset movement plane perpendicular to the optical axis of the wide-angle camera are determined. The number of limit movement distances reflect the distances of the calibration component from its initial position to multiple edge positions within the field of view of the wide-angle camera. Based on the multiple extreme movement distances, the calibration component is moved by the adjustment device to reach multiple edge positions respectively; at each edge position, the calibration component's attitude is adjusted by rotating the adjustment device, and multiple shots are taken using the wide-angle camera to determine the standard attitude of the calibration component at each edge position and the first angle data of the rotation of the calibration component driven by the adjustment device at the standard attitude; and Based on the first angle data at each of the said edge locations, the parameters for distortion correction of the wide-angle camera are determined.

Images