Method and device for measuring intersection point position of camera reference axis and sensor plane

Abstract

The invention discloses a method and device for measuring the intersection point position of a camera reference axis and a sensor plane, and relates to the technical field of semiconductor packaging. According to the method, the coordinate system is constructed on the sensor plane, the origin of the coordinate system and the first imaging coordinate point are determined, then the camera rotates around the camera reference axis to obtain a plurality of new imaging coordinate points, and the imaging coordinate point set is constructed; the coordinates of the intersection point of the camera reference axis and the camera sensor surface are determined according to the imaging coordinate point set, a reliable basis is provided for analyzing the deviation of the camera reference axis and the sensor center point, and camera calibration is facilitated; meanwhile, through multiple times of rotation measurement, the recognition precision is enhanced, and errors possibly existing in single measurement are effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor packaging technology, and in particular to a method and device for measuring the intersection position of a camera reference axis and a sensor plane. Background Art

[0002] When packaging the camera, due to the position deviation of the camera sensor installed in the camera, the intersection position of the camera reference axis and the sensor plane is not fixed when each camera is installed, which leads to a series of optical and imaging quality problems. For example, if the intersection of the camera reference axis and the sensor plane does not fall accurately on the center point of the sensor plane, an optical axis offset problem will occur. When designing the optical system, it is usually assumed that the optical axis passes through the center of the sensor plane. If the actual intersection deviates from the center, it will cause uneven field of view or even image field center offset, and increase the geometric distortion of the imaging area. Moreover, this deviation may also cause focusing errors and reduced resolution. The optical axis offset will prevent the optimal focal plane of the lens from completely matching the sensor plane, resulting in out-of-focus in some areas, especially in large aperture or high-resolution imaging scenarios.

[0003] Therefore, developing a method to measure the intersection position of the camera reference axis and the sensor plane has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present application is that the position deviation of the existing camera sensor installed in the camera leads to a series of technical problems in optics and imaging quality.

[0005] In order to solve the above technical problems, the embodiment of the present application provides a method for measuring the intersection position of a camera reference axis and a sensor plane, which adopts the following technical solution:

[0006] A method for measuring the intersection position of a camera reference axis and a sensor plane, comprising:

[0007] Construct a coordinate system on the camera sensor plane and determine the origin of the coordinate system;

[0008] Determine the first imaging coordinate point according to the origin of the coordinate system;

[0009] The camera is rotated around the camera reference axis according to a preset number of rotations n, where n ≥ 2 and n is a positive integer;

[0010] After each camera rotation is completed, a new imaging coordinate point is determined according to the origin of the coordinate system to obtain N new imaging coordinate points, where N = n;

[0011] Construct a coordinate point set based on all imaging coordinate points;

[0012] According to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point.

[0013] Furthermore, the camera reference axis is a camera flange axis or a lens optical axis.

[0014] Further, identifying the camera reference axis and rotating the camera around the camera reference axis according to a preset number of rotations n specifically includes:

[0015] Taking the camera reference axis as the rotation center, calculate the rotation angle of the camera each time according to the preset rotation number n;

[0016] According to each camera rotation angle and the preset rotation times n, the camera is rotated around the camera reference axis.

[0017] Furthermore, the preset number of rotations n is 3 times, and the rotation angle of the camera each time is 90°. The measurement method includes:

[0018] The position of the camera before rotation is set as camera rotation 0°. After the camera is rotated three times, the obtained camera rotation positions are 90°, 180°, and 270° respectively.

[0019] Further, according to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point, which specifically includes:

[0020] Based on all imaging coordinate points in the coordinate point set, the least square method is used to perform imaging coordinate point fitting to generate a coordinate point fitting circle;

[0021] Determine the coordinates of the center of the coordinate point fitting circle;

[0022] The coordinates of the center of the circle fitted to the coordinate point are the coordinates of the intersection of the camera reference axis and the camera sensor plane, and the intersection of the axis plane is obtained.

[0023] Further, according to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point, which specifically includes:

[0024] Extracting a number of coordinate points from the coordinate point set in a manner with replacement until every combination of coordinate points in the coordinate point set has been extracted, wherein the number of coordinate points in each combination of coordinate points is greater than or equal to 3;

[0025] For each extracted coordinate point, the circumscribed circle of the coordinate point is constructed using the circumscribed circle method;

[0026] Determine the center coordinates of the circumscribed circle of all coordinate points;

[0027] The coordinates of the intersection point between the camera reference axis and the camera sensor plane are calculated according to the center coordinates of the circumscribed circle of all coordinate points to obtain the axis plane intersection point.

[0028] Furthermore, the number of extracted coordinate points is 3, and the measurement method includes:

[0029] For each of the three coordinate points extracted, the triangle circumscribed circle method is used to construct the triangle circumscribed circle;

[0030] Determine the coordinates of the center of the circumscribed circle of all triangles;

[0031] The coordinates of the intersection point between the camera reference axis and the camera sensor plane are calculated according to the coordinates of the center of the circumscribed circle of all triangles to obtain the intersection point of the axis plane.

[0032] Furthermore, the coordinates of the intersection of the camera reference axis and the camera sensor plane are calculated according to the coordinates of the center of the circumscribed circle of all triangles to obtain the intersection of the axis plane, which specifically includes:

[0033] Calculate the average value of the center coordinates of all triangle circumscribed circles to obtain the average value of the center coordinates;

[0034] The average value of the circle center coordinates is used as the coordinates of the intersection of the camera reference axis and the camera sensor plane to obtain the axis plane intersection.

[0035] Furthermore, a coordinate system is constructed on the camera sensor plane, and the origin of the coordinate system is determined, specifically including:

[0036] The lateral resolution of the camera sensor plane is used as the X-axis scale value of the coordinate system;

[0037] The vertical resolution of the camera sensor plane is used as the Y-axis scale value of the coordinate system;

[0038] The coordinates of the upper left corner of the camera sensor will be identified and used as the origin of the coordinate system.

[0039] In order to solve the above technical problems, the embodiment of the present application further provides a device for measuring the intersection position of a camera reference axis and a sensor plane, which adopts the following technical solution:

[0040] A device for measuring the intersection position of a camera reference axis and a sensor plane, the device for measuring the intersection position of a camera reference axis and a sensor plane executes the above-mentioned method for measuring the intersection position of a camera reference axis and a sensor plane.

[0041] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0042] The present application constructs a coordinate system on the sensor plane and determines the origin of the coordinate system, then obtains multiple imaging coordinate points by rotating the camera around the camera reference axis, and calculates the coordinates of the intersection of the camera reference axis and the camera sensor surface based on the imaging coordinate points, thereby providing a reliable basis for analyzing the deviation between the camera reference axis and the sensor center point for camera calibration; at the same time, through multiple rotation measurements, the recognition accuracy is enhanced, and the errors that may exist in a single measurement are effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the solutions in the present application or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 A flow chart showing an embodiment of a method for measuring the intersection position of a camera reference axis and a sensor plane according to the present application;

[0045] Figure 2 A schematic diagram of a coordinate system is shown according to an embodiment of a method for measuring the intersection position of a camera reference axis and a sensor plane according to the present application;

[0046] Figure 3 A schematic structural diagram of a camera body according to an embodiment of the present application is shown;

[0047] Figure 4 A schematic diagram showing the position of the intersection of the camera reference axis and the sensor plane according to one embodiment of the present application;

[0048] Figure 5 One of the structural schematic diagrams of a device for measuring the position of an axis plane intersection point based on a lens optical axis in one embodiment of the present application is shown;

[0049] Figure 6 A second structural schematic diagram of a device for measuring the position of an axis plane intersection based on a lens optical axis in one embodiment of the present application is shown;

[0050] Figure 7 A schematic structural diagram of a camera lens according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0052] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] Please refer to Figure 1 The present application discloses a method for measuring the intersection position of a camera reference axis and a sensor plane, which specifically includes the following steps:

[0054] S1, constructing a coordinate system on the camera sensor plane and determining the origin of the coordinate system;

[0055] S2, determining a first imaging coordinate point according to the origin of the coordinate system;

[0056] S3, rotating the camera around the camera reference axis according to a preset number of rotations n, where n≥2 and n is a positive integer;

[0057] S4, after each camera rotation is completed, a new imaging coordinate point is determined according to the origin of the coordinate system to obtain N new imaging coordinate points, where N=n;

[0058] Among them, after each camera rotation is completed, a new imaging coordinate point is obtained, and a total of N new imaging coordinate points are obtained, and N new imaging coordinate points = {second imaging coordinate point, third imaging coordinate point, fourth imaging coordinate point, ..., Nth imaging coordinate point, N+1th imaging coordinate point}.

[0059] S5, constructing a coordinate point set according to all imaging coordinate points;

[0060] The coordinate point set includes N+1 imaging coordinate points, where N+1 imaging coordinate point={first imaging coordinate point, second imaging coordinate point, third imaging coordinate point, fourth imaging coordinate point, ..., Nth imaging coordinate point, N+1th imaging coordinate point}.

[0061] S6, calculating the intersection of the camera reference axis and the camera sensor plane according to the coordinate point set to obtain the axis plane intersection.

[0062] In the above embodiment, the present application constructs a coordinate system on the sensor plane and determines the origin of the coordinate system, and then obtains multiple imaging coordinate points by rotating the camera around the camera reference axis, and calculates the coordinates of the intersection of the camera reference axis and the camera sensor surface based on the imaging coordinate points, thereby providing a reliable basis for analyzing the deviation between the camera reference axis and the sensor center point for camera calibration; at the same time, through multiple rotation measurements, the recognition accuracy is enhanced, and the errors that may exist in a single measurement are effectively reduced.

[0063] Furthermore, the camera reference axis is the camera flange axis or the lens optical axis. The camera is rotated around the camera flange axis or the lens optical axis according to a preset number of rotations. When rotating the camera, the camera reference axis (i.e., the camera flange axis or the lens optical axis) is used as the rotation center, and the rotation angle of each camera is calculated according to the preset number of rotations. The calculation formula for the rotation angle of each camera is as follows:

[0064]

[0065] In the formula, is the rotation angle of the camera each time, and n is the preset number of rotations. And the preset rotation times n, the camera rotates around the camera reference axis.

[0066] Furthermore, the preset number of rotations n is greater than or equal to 2 times. The greater the number of rotations, the more accurate the calculated intersection position of the camera reference axis and the camera sensor plane is. Figure 2 , taking the preset rotation number n as 3 times as an example, the rotation angle of the camera each time is calculated according to the above formula is 90°.

[0067] Furthermore, the lateral resolution of the camera sensor plane is used as the X-axis scale value of the coordinate system, and the longitudinal resolution of the camera sensor plane is used as the Y-axis scale value of the coordinate system, and a coordinate system is constructed on the sensor plane.

[0068] Furthermore, the position of the area where the camera sensor is located is identified, and any point on the area where the camera sensor is located can be determined as the origin of the coordinate system. Preferably, the coordinates of the upper left corner of the camera sensor are determined as the origin of the coordinate system, the coordinates of the upper left corner of the camera sensor are identified, and the coordinates of the upper left corner of the camera sensor are used as the origin of the coordinate system (0, 0). After each rotation of the camera around the camera flange axis or the lens optical axis, the position of the origin of the coordinate system will change accordingly. For example, the initial position is the coordinate point of the upper left corner of the camera sensor. When the camera rotates 90° relative to the initial position, the origin of the coordinate system becomes the coordinate point of the upper right corner of the camera sensor. When the camera rotates 180° relative to the initial position, the origin of the coordinate system becomes the coordinate point of the lower right corner of the camera sensor. When the camera rotates 270° relative to the initial position, the origin of the coordinate system becomes the coordinate point of the lower left corner of the camera sensor.

[0069] The position of the camera before rotation is set as the camera rotation of 0°. At this time, the first imaging coordinate point M1 (x1, y1) is determined; after the camera rotates 3 times, the obtained camera rotation positions are 90°, 180°, and 270° respectively. The imaging coordinate points after each camera rotation are determined in turn to obtain 3 new imaging coordinate points, namely the second imaging coordinate point M2 (x2, y2), the third imaging coordinate point M3 (x3, y3), and the fourth imaging coordinate point M4 (x4, y4). At this time, a total of 4 imaging coordinate points are obtained to form a coordinate point set. The coordinate point set includes the first imaging coordinate point M1 (x1, y1), the second imaging coordinate point M2 (x2, y2), the third imaging coordinate point M3 (x3, y3), and the fourth imaging coordinate point M4 (x4, y4). Based on these 4 imaging coordinate points, the intersection of the camera reference axis and the camera sensor plane can be calculated to obtain the axis plane intersection.

[0070] Further, according to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point, which specifically includes:

[0071] Based on all imaging coordinate points in the coordinate point set, the least square method is used to perform imaging coordinate point fitting to generate a coordinate point fitting circle;

[0072] Determine the coordinates of the center of the coordinate point fitting circle;

[0073] The coordinates of the center of the circle fitted to the coordinate point are the coordinates of the intersection of the camera reference axis and the camera sensor plane, and the intersection of the axis plane is obtained.

[0074] Specifically, based on all the imaging coordinate points in the coordinate point set, the coordinate points are first fitted by the least squares method to generate a fitting circle that reflects the distribution law of the imaging coordinate points. The center coordinates of the fitting circle represent the geometric center of the imaging point and can accurately reflect the projection position of the camera reference axis on the sensor plane.

[0075] This method can avoid the influence of single-point measurement errors on the results, and use global data to improve fitting accuracy and robustness. Finally, the center of the fitting circle is used as the intersection of the camera reference axis and the sensor plane, that is, the axis-plane intersection. This method is simple and efficient, and can ensure the calculation accuracy of the intersection coordinates, providing a reliable data basis for camera calibration and helping to optimize imaging quality.

[0076] Further, according to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point, which specifically includes:

[0077] Extracting a number of coordinate points from the coordinate point set in a manner with replacement until every combination of coordinate points in the coordinate point set has been extracted, wherein the number of coordinate points in each combination of coordinate points is greater than or equal to 3;

[0078] For each extracted coordinate point, the circumscribed circle of the coordinate point is constructed using the circumscribed circle method;

[0079] Determine the center coordinates of the circumscribed circle of all coordinate points;

[0080] The coordinates of the intersection point between the camera reference axis and the camera sensor plane are calculated according to the center coordinates of the circumscribed circle of all coordinate points to obtain the axis plane intersection point.

[0081] Specifically, by extracting coordinate points one by one and constructing a circumscribed circle, the information of all coordinate points can be effectively utilized to avoid calculation deviations caused by single-point errors. In the circumscribed circle method, several coordinate points are selected each time to determine a unique circumscribed circle, whose center is the geometric center of these points, reflecting the projection law of the reference axis on the sensor plane.

[0082] By repeatedly extracting and calculating the circumscribed circle, a set of reliable circle center coordinates is obtained. These circle center coordinates are further used to fit and calculate the intersection position of the camera reference axis and the sensor plane, that is, the axis-plane intersection. The final intersection coordinates comprehensively consider the results of multiple measurements and calculations, thereby improving positioning accuracy and stability.

[0083] By making full use of the information of all imaging coordinate points and combining the geometric characteristics of the circumscribed circle, high-precision measurement of the intersection of the camera reference axis and the sensor plane is achieved, thereby improving the imaging quality.

[0084] Furthermore, the number of extracted coordinate points is 3, and the measurement method includes:

[0085] For each of the three coordinate points extracted, the triangle circumscribed circle method is used to construct the triangle circumscribed circle;

[0086] Determine the coordinates of the center of the circumscribed circle of all triangles;

[0087] The coordinates of the intersection point between the camera reference axis and the camera sensor plane are calculated according to the coordinates of the center of the circumscribed circle of all triangles to obtain the intersection point of the axis plane.

[0088] Specifically, take the case where the camera rotates three times and three coordinate points are extracted. The coordinate point set includes the first imaging coordinate point M1 (x1, y1), the second imaging coordinate point M2 (x2, y2), the third imaging coordinate point M3 (x3, y3), and the fourth imaging coordinate point M4 (x4, y4). Three coordinate points are extracted each time with replacement. The extraction results are as follows:

[0089] Table 1. Results of imaging coordinate point extraction

[0090] Number of extractions Extraction results 1 M1(x1, y1), M2(x2, y2), M3(x3, y3) 2 M1(x1, y1), M2(x2, y2), M4(x4, y4) 3 M1(x1, y1), M3(x3, y3), M4(x4, y4) 4 M2(x2, y2), M3(x3, y3), M4(x4, y4)

[0091] As shown in Table 1, when the camera rotates 3 times and extracts 3 coordinate points, the number of extractions is 4, and a total of 4 triangle circumscribed circles can be constructed. The average value of the center coordinates of the 4 triangle circumscribed circles is calculated to obtain the average value of the center coordinates, and the average value of the center coordinates is used as the coordinates of the intersection of the camera reference axis and the camera sensor plane to obtain the axis plane intersection. Specific embodiment 1

[0093] refer to Figure 1-Figure 4 , the camera reference axis takes the camera flange axis L1 as an example, the camera includes a camera body 100, a camera sensor 101, and a camera flange 102, the camera flange axis L1 intersects with the camera sensor 101 at point G, and the center point of the camera sensor 101 is point S. Since there is a position deviation when the camera sensor 101 is installed on the camera, the intersection point G of the camera flange axis L1 and the plane where the camera sensor 101 is located of the installation reference of each camera is not fixed, that is, the intersection point G of the camera flange axis L1 and the plane where the camera sensor 101 is located in actual use does not coincide with the center point S of the sensor.

[0094] When measuring the intersection G of the camera flange axis L1 and the plane where the camera sensor 101 is located, the upper left corner of the camera sensor 101 is used as the origin of the coordinate system (0, 0), the horizontal resolution is used as the X-axis scale value, and the vertical resolution is used as the Y-axis scale value. The camera body 100 is installed with the camera flange axis L1 as a reference, and an image is formed on the camera sensor 101 using a marking point. Here, a cross cursor is taken as an example, and the center point of the cross cursor is identified through software image processing, that is, the first imaging coordinate point M1 (x1, y1). At this time, the camera is in the initial position, that is, the camera installation angle (rotation angle) is regarded as 0°; after the camera rotates 90° around the camera flange axis L1 relative to the initial position, the coordinates of the center point of the cross cursor are identified, that is, the second imaging coordinate point M2 (x2, y2); similarly, after the camera rotates 180° around the camera flange axis L1 relative to the initial position, the coordinates of the center point of the cross cursor are identified, that is, the third imaging coordinate point M3 (x3, y3); after the camera rotates 270° around the camera flange axis L1 relative to the initial position, the coordinates of the center point of the cross cursor are identified, that is, the fourth imaging coordinate point M4 (x4, y4).

[0095] The above four imaging coordinate points are fitted by the least squares method to generate a fitting circle that reflects the distribution law of the imaging coordinate points, and the center of the fitting circle is determined. The center of the fitting circle is used as the intersection G of the camera flange axis L1 and the plane where the camera sensor 101 is located, that is, the intersection position of the camera flange axis L1 and the plane where the camera sensor 101 is located.

[0096] Alternatively, three imaging coordinate points may be extracted with replacement and the triangle circumscribed circle method may be used to obtain the coordinates of the center of the circle. The coordinates of the four center of the circle may be calculated four times in sequence. The average value of the four center of the circle coordinates may be taken to obtain the intersection point G of the camera flange axis L1 and the plane where the camera sensor 101 is located, that is, the intersection position of the camera flange axis L1 and the plane where the camera sensor 101 is located.

[0097] In the above embodiment, the present application constructs a coordinate system on the sensor plane and determines the origin of the coordinate system, and then obtains multiple imaging coordinate points by rotating the camera around the camera reference axis, and calculates the coordinates of the intersection of the camera reference axis and the camera sensor surface based on the imaging coordinate points, thereby providing a reliable basis for analyzing the deviation between the camera reference axis and the sensor center point for camera calibration; at the same time, through multiple rotation measurements, the recognition accuracy is enhanced, and the errors that may exist in a single measurement are effectively reduced. Specific embodiment 2

[0099] refer to Figure 1-Figure 2 as well as Figure 5-Figure 6Taking the fixture optical axis L2 as an example of the camera reference axis, the measuring mechanism includes a camera mounting seat 200 and a fixture body 300. The camera mounting seat 200 includes a first mounting seat reference surface 201, a second mounting seat reference surface 202, a third mounting seat reference surface 203, a fourth mounting seat reference surface 204, a first spring clip 205 and a second spring clip 206. The first mounting seat reference surface 201, the second mounting seat reference surface 202 and the third mounting seat reference surface 203 are arranged in the camera mounting seat 200, and the fourth mounting seat reference surface 204, the first spring clip 205 and the second spring clip 206 are arranged on the outer side of the camera mounting seat 200.

[0100] The camera mount 200 also includes a mount flange 207. A main body mounting hole 303 is provided on the fixture main body 300. The hole axis of the main body mounting hole 303 is the fixture optical axis L2. The flange axis of the mount flange 207 and the main body mounting hole 303 are coaxially matched, so that the camera can rotate freely around the fixture optical axis L2. The fourth mount reference surface 204 is kept in close contact with the fixture main body reference surface 302.

[0101] The first spring piece 205 and the second spring piece 206 on the fixture body 300 can realize quick assembly and disassembly of the camera, improve the efficiency of measurement, and avoid damage to the camera housing.

[0102] The camera body 100 includes a first camera reference surface 103, a second camera reference surface 104 and a third camera reference surface 105. When the camera body 100 is mounted on the camera mounting seat 200, the first camera reference surface 103 is kept in close contact with the first mounting seat reference surface 201, the second camera reference surface 104 is kept in close contact with the second mounting seat reference surface 202, and the third camera reference surface 105 is kept in close contact with the third mounting seat reference surface 203. The first spring piece 205 and the second spring piece 206 generate elastic force by deformation to fix the camera body 100. The camera mounting seat 200 is close to the fixture body 300, and the fourth mounting seat reference surface 204 is in close contact with the fixture body 300. The fixture body 300 is provided with a first optical system 301, and the first optical system 301 is used for optical testing.

[0103] When measuring the intersection G of the fixture optical axis L2 and the plane where the camera sensor 101 is located, the upper left corner of the camera sensor 101 is used as the origin of the coordinate system (0, 0), the horizontal resolution is used as the X-axis scale value, and the vertical resolution is used as the Y-axis scale value. The camera body 100 is installed with the fixture optical axis L2 as a reference, and an image is formed on the camera sensor 101 using a marking point. Here, a cross cursor is taken as an example, and the center point of the cross cursor, i.e., the first imaging coordinate point M1 (x1, y1), is identified through software image processing. At this time, the camera is in the initial position, i.e., the camera installation angle (rotation angle) is regarded as 0°; after the camera rotates 90° around the fixture optical axis L2 relative to the initial position, the coordinates of the center point of the cross cursor are identified, i.e., the second imaging coordinate point M2 (x2, y2); similarly, after the camera rotates 180° around the fixture optical axis L2 relative to the initial position, the coordinates of the center point of the cross cursor are identified, i.e., the third imaging coordinate point M3 (x3, y3); after the camera rotates 270° around the fixture optical axis L2 relative to the initial position, the coordinates of the center point of the cross cursor are identified, i.e., the fourth imaging coordinate point M4 (x4, y4).

[0104] The above four imaging coordinate points are fitted by the least squares method to generate a fitting circle that reflects the distribution law of the imaging coordinate points, and the center of the fitting circle is determined. The center of the fitting circle is used as the intersection G of the fixture optical axis L2 and the plane where the camera sensor 101 is located, that is, the intersection position of the fixture optical axis L2 and the plane where the camera sensor 101 is located.

[0105] Alternatively, three imaging coordinate points may be extracted with replacement and the triangle circumscribed circle method may be used to obtain the coordinates of the center of the circle. The coordinates of the four center of the circle may be calculated four times in sequence. The average value of the four center of the circle coordinates may be taken to obtain the intersection point G of the fixture optical axis L2 and the plane where the camera sensor 101 is located, that is, the intersection position of the fixture optical axis L2 and the plane where the camera sensor 101 is located.

[0106] The present application realizes the rotation of the camera around the jig optical axis L2 by rotating the camera mounting base 200 around the jig optical axis L2, obtains the coordinates of the center of the field of view of the four positions in the intercepted image, and automatically calculates the center of the circle where the four coordinates are located, and obtains the coordinates of the intersection of the jig optical axis L2 and the plane where the camera sensor 101 is located.

[0107] Please refer to Figure 5-Figure 7 In this application, two vertical reference planes (first camera reference plane 103 and second camera reference plane 104) of the camera housing are used as the installation reference. The fixture body 300 and the lens 400 have the same reference for lens installation, and both are installed with the two vertical reference planes of the camera housing. The position of the optical path is consistent, so as to ensure that the coordinates of the intersection of the optical axis (the fixture optical axis L2 and the lens optical axis L3) and the sensor do not change, ensure the consistency of the results, and at the same time, the camera can be fixedly installed on the lens with the camera housing as the reference.

[0108] After completing the measurement of the intersection position of the jig optical axis L2 and the plane where the camera sensor 101 is located, the camera is installed in the lens 400, and the camera calibration is performed based on the intersection position of the lens optical axis L3 and the plane where the camera sensor 101 is located. The optical path of the lens 400 is consistent with the optical path of the jig body 300. The lens 400 includes a lens body 401, a camera fixing frame 402, and a second optical system 403. The lens body 401 includes a first lens body reference plane 411, a second lens body reference plane 412, and a third lens body reference plane 413. When the camera is fixed in the lens 400, the first camera reference plane 103 is kept in close contact with the first lens body reference plane 411, the second camera reference plane 104 is kept in close contact with the second lens body reference plane 412, and the third camera reference plane 105 is kept in close contact with the third lens body reference plane 413.

[0109] The lens 400 is also provided with a ball plunger 421, and the camera fixing frame 402 is used in conjunction with the ball plunger 421 to fix the camera to the lens body 401. The lens 400 is also provided with a second optical system 405, and the second optical system 405 is used for optical testing.

[0110] In the above embodiment, the present application constructs a coordinate system on the sensor plane and determines the origin of the coordinate system, and then obtains multiple imaging coordinate points by rotating the camera around the camera reference axis, and calculates the coordinates of the intersection of the camera reference axis and the camera sensor surface based on the imaging coordinate points, thereby providing a reliable basis for analyzing the deviation between the camera reference axis and the sensor center point for camera calibration; at the same time, through multiple rotation measurements, the recognition accuracy is enhanced, and the errors that may exist in a single measurement are effectively reduced. Specific embodiment 3

[0112] The present application also discloses a device for measuring the intersection position of a camera reference axis and a sensor plane. The device for measuring the intersection position of a camera reference axis and a sensor plane executes the method for measuring the intersection position of a camera reference axis and a sensor plane as described above.

[0113] The camera reference axis is the camera flange axis or the lens optical axis. The camera is rotated around the camera flange axis or the lens optical axis by a preset number of rotations. When rotating the camera, the camera reference axis (i.e., the camera flange axis or the lens optical axis) is used as the rotation center, and the rotation angle of each camera is calculated according to the preset number of rotations.

[0114] The preset number of rotations is greater than or equal to 2 times. The greater the number of rotations, the more accurate the calculated intersection position of the camera reference axis and the camera sensor plane is.

[0115] The implementation process of the device for measuring the intersection position of the camera reference axis and the sensor plane is consistent with the implementation process of the method for measuring the intersection position of the camera reference axis and the sensor plane described above, and will not be repeated here.

[0116] In the above embodiment, the present application constructs a coordinate system on the sensor plane and determines the origin of the coordinate system, and then obtains multiple imaging coordinate points by rotating the camera around the camera reference axis, and calculates the coordinates of the intersection of the camera reference axis and the camera sensor surface based on the imaging coordinate points, thereby providing a reliable basis for analyzing the deviation between the camera reference axis and the sensor center point for camera calibration; at the same time, through multiple rotation measurements, the recognition accuracy is enhanced, and the errors that may exist in a single measurement are effectively reduced.

[0117] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is similarly within the scope of patent protection of this application.

Claims

1. A method for measuring the intersection position of a camera reference axis and a sensor plane, characterized in that: include: Constructing a coordinate system on the camera sensor plane and determining the origin of the coordinate system; Determine a first imaging coordinate point according to the origin of the coordinate system; The camera is rotated around the camera reference axis according to a preset number of rotations n, where n ≥ 2 and n is a positive integer; After each camera rotation is completed, a new imaging coordinate point is determined according to the origin of the coordinate system to obtain N new imaging coordinate points, where N=n; Construct a coordinate point set based on all imaging coordinate points; According to the coordinate point set, the intersection point of the camera reference axis and the camera sensor plane is calculated to obtain the axis plane intersection point.

2. The method for measuring the intersection position of the camera reference axis and the sensor plane according to claim 1, characterized in that: The camera reference axis is the camera flange axis or the lens optical axis.

3. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 1, characterized in that: The step of rotating the camera around the camera reference axis according to a preset number of rotations n specifically includes: Taking the camera reference axis as the rotation center, calculating the rotation angle of the camera each time according to the preset rotation number n; According to each rotation angle of the camera and the preset rotation number n, the camera is rotated around the camera reference axis.

4. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 3, characterized in that: The preset number of rotations n is 3 times, and the rotation angle of the camera is 90° each time. The measurement method includes: The position of the camera before rotation is set as camera rotation 0°. After the camera is rotated three times, the obtained camera rotation positions are 90°, 180°, and 270° respectively.

5. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 1, characterized in that: The step of calculating the intersection of the camera reference axis and the camera sensor plane according to the coordinate point set to obtain the axis plane intersection specifically includes: Based on all the imaging coordinate points in the coordinate point set, the least square method is used to perform imaging coordinate point fitting to generate a coordinate point fitting circle; Determine the center coordinates of the coordinate point fitting circle; The coordinates of the center of the circle fitted with the coordinate point are the coordinates of the intersection of the camera reference axis and the camera sensor plane, and the axis plane intersection is obtained.

6. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 1, characterized in that: The step of calculating the intersection of the camera reference axis and the camera sensor plane according to the coordinate point set to obtain the axis plane intersection specifically includes: Extracting a number of coordinate points from the coordinate point set in a manner with replacement until every combination of coordinate points in the coordinate point set has been extracted, wherein the number of coordinate points in each combination of coordinate points is greater than or equal to 3; For each extracted coordinate point, the circumscribed circle of the coordinate point is constructed using the circumscribed circle method; Determine the center coordinates of the circumscribed circles of all the coordinate points; The coordinates of the intersection point of the camera reference axis and the camera sensor plane are calculated according to the coordinates of the center of the circumscribed circle of all the coordinate points to obtain the axis plane intersection point.

7. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 6, characterized in that: The number of extracted coordinate points is 3, and the measurement method includes: For each of the three coordinate points extracted, the triangle circumscribed circle method is used to construct the triangle circumscribed circle; Determine the coordinates of the centers of the circumscribed circles of all the triangles; The coordinates of the intersection point of the camera reference axis and the camera sensor plane are calculated according to the coordinates of the centers of all the triangle circumscribed circles to obtain the axis plane intersection point.

8. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 7, characterized in that: The step of calculating the coordinates of the intersection of the camera reference axis and the camera sensor plane according to the coordinates of the centers of all the triangle circumscribed circles to obtain the axis plane intersection specifically includes: Calculate the average value of the center coordinates of all the triangle circumscribed circles to obtain the average value of the center coordinates; The average value of the circle center coordinates is used as the coordinates of the intersection of the camera reference axis and the camera sensor plane to obtain the axis plane intersection.

9. The method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in claim 1, characterized in that: The step of constructing a coordinate system on the camera sensor plane and determining the origin of the coordinate system specifically includes: Using the lateral resolution of the camera sensor plane as the X-axis scale value of the coordinate system; Using the longitudinal resolution of the camera sensor plane as the Y-axis scale value of the coordinate system; The coordinates of the upper left corner of the camera sensor are identified and used as the origin of the coordinate system.

10. A device for measuring the intersection position of a camera reference axis and a sensor plane, characterized in that: The device for measuring the intersection position of the camera reference axis and the sensor plane executes the method for measuring the intersection position of the camera reference axis and the sensor plane as claimed in any one of claims 1 to 9.

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