Calibration board

Abstract

The utility model discloses a calibration plate which comprises a body plate and at least two calibration bosses, the body plate is provided with a reference surface, and the calibration bosses are arranged on the reference surface in parallel; the calibration boss is provided with a first side surface, a second side surface and a third side surface, the extension directions of the first side surface, the second side surface and the third side surface are parallel to the extension direction of the calibration boss, the first side surface is parallel to the reference surface, and obtuse angles are formed between the second side surface and the first side surface and between the third side surface and the first side surface; the spacing distances between the first side surfaces of different calibration bosses and the reference surface are different. Corner points of the first side face, the second side face and the third side face of the calibration boss can provide corresponding calibration coordinates, the calibration plate provided by the utility model has three-dimensional calibration parameters and is wide in application range, a geometric model imaged by a camera is more comprehensive and more accurate, the accuracy of a calibration result of the camera can be improved, the structure is simple, the processing is convenient, and the cost is low. The method is low in production cost and can be used for calibration of double-camera and multi-camera algorithms.

Description

Technical Field

[0001] The utility model relates to the technical field of calibration, and more specifically, to a calibration plate. Background Art

[0002] With the development of science and technology, the hardware and parameters of cameras are constantly improving, and are increasingly used in production and life, such as machine vision, image measurement, photogrammetry, etc.

[0003] To ensure the accuracy of camera detection and measurement results, camera calibration is typically required. This process typically involves operating the camera to image a calibration plate with patterns at fixed intervals. A calibration algorithm then calculates the geometric model of the camera's image. Based on this geometric model, the camera's lens distortion is corrected and the conversion relationship between physical dimensions and pixels is determined.

[0004] Existing calibration plates can generally only calibrate the parameters within the two-dimensional plane of the camera, and cannot calibrate the parameters of the third dimension (for example, when the two-dimensional directions are the length and width directions, the third dimension is the height direction), and their scope of use is relatively small; and, since the parameters of the third dimension cannot be calibrated, the imaging geometric model of the calibrated camera is less accurate, affecting the accuracy of the camera calibration results.

[0005] Therefore, how to improve the accuracy of camera calibration results has become a technical problem that needs to be solved urgently by those skilled in the art. Utility Model Content

[0006] In view of this, an object of the present invention is to provide a calibration plate to improve the accuracy of camera calibration results.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] A calibration plate comprises a main body plate and a calibration boss, wherein the main body plate has a reference surface, and the calibration bosses are at least two and are arranged parallel to the reference surface;

[0009] The calibration boss has a first side surface, a second side surface, and a third side surface. The extension directions of the first side surface, the second side surface, and the third side surface are all parallel to the extension direction of the calibration boss. The first side surface is arranged parallel to the reference plane, and the second side surface and the third side surface are arranged at an obtuse angle to the first side surface.

[0010] The spacing distances between the first side surfaces of different calibration bosses and the reference surface are different.

[0011] Optionally, in the above-mentioned calibration plate, two of the calibration bosses are respectively a first boss and a second boss, an identification portion is provided on the main body plate, the identification portion is spaced a first distance from the first boss, and the identification portion is spaced a second distance from the second boss, and the first distance is smaller than the second distance.

[0012] Optionally, in the above-mentioned calibration plate, the identification portion is an identification hole opened on the main body plate; or, the identification portion is a boss structure provided on the main body plate.

[0013] Optionally, in the above-mentioned calibration plate, a grid structure is provided on the surfaces of the first side surface, the second side surface and the third side surface, and the corner points of each grid in the grid structure are used to provide calibration coordinates.

[0014] Optionally, in the calibration plate, perpendicular to the extension direction of the calibration boss, the extension lengths of the first side surfaces of different calibration bosses are different;

[0015] The included angles between the second side surfaces of different calibration bosses and the reference plane are the same or different, and the included angles between the third side surfaces of different calibration bosses and the reference plane are the same or different.

[0016] Optionally, in the above-mentioned calibration plate, the end surfaces of both ends of the calibration boss along the extension direction are respectively the fourth side surface and the fifth side surface;

[0017] The fourth side surface and the fifth side surface are arranged perpendicular to or at an obtuse angle to the first side surface.

[0018] Optionally, in the above calibration plate, a first calibration hole is provided on the main body plate; and / or,

[0019] The calibration boss is provided with a second calibration hole.

[0020] Optionally, in the above-mentioned calibration plate, the surfaces of the main body plate and the calibration boss are matte-finished; and / or,

[0021] The main body plate and the calibration boss are made of metal, plastic or resin.

[0022] Optionally, in the above-mentioned calibration plate, the calibration boss and the main body plate are an integrated structure and are integrally formed.

[0023] Optionally, in the above-mentioned calibration plate, the main body plate is provided with connection holes for connection.

[0024] The calibration plate provided by the present invention includes a main body plate and a calibration boss. The main body plate has a reference surface, and there are at least two calibration bosses, which are arranged parallel to the reference surface. The calibration boss has a first side, a second side, and a third side. The extension directions of the first side, the second side, and the third side are all parallel to the extension direction of the calibration boss, and the first side is arranged parallel to the reference surface, and the second side and the third side are arranged at an obtuse angle to the first side. The spacing distance between the first side and the reference surface of different calibration bosses is different. Among them, the corner points of the first side, the second side, and the third side of the calibration boss can provide corresponding calibration coordinates. The width and length of the reference surface are defined to extend along the X direction and the Y direction respectively, and the thickness direction of the calibration plate extends along the Z direction. Since the spacing distance between the first side and the reference surface of different calibration bosses is different, that is, the first side of different calibration bosses is at different positions in the Z direction, multiple sets of real data can be provided for algorithm calibration in the Z direction. The position coordinates of the calibration boss on the reference surface can provide coordinate data in the X direction and the Y direction. By collecting image data of the calibration plate, the camera to be calibrated can simultaneously obtain high-precision real data in the X, Y, and Z directions, so that the camera to be calibrated can complete high-precision calibration by scanning the calibration plate once.

[0025] Compared with the existing technology, the calibration plate provided by the utility model has calibration parameters in three dimensions, a wide range of uses, and a more comprehensive and accurate geometric model of camera imaging, which can improve the accuracy of camera calibration results. It has a simple structure, is easy to process, and has low production costs. It can be used for the calibration of dual-camera and multi-camera algorithms. At the same time, the calibration boss meets the accuracy requirements required for calibration while having low processing difficulty requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is an axonometric view of the first calibration plate disclosed in an embodiment of the present utility model;

[0028] Figure 2 This is a front view of the first calibration plate disclosed in an embodiment of the present utility model;

[0029] Figure 3 A side view of the first calibration plate disclosed in an embodiment of the present utility model;

[0030] Figure 4 This is a front view of the second calibration plate disclosed in an embodiment of the present utility model;

[0031] Figure 5 This is a front view of the third calibration plate disclosed in an embodiment of the present utility model.

[0032] Among them, 100 is the main body plate, 101 is the identification part, 102 is the chamfered structure, 110 is the first calibration hole, 200 is the calibration boss, 201 is the first side, 202 is the second side, 203 is the third side, 204 is the fourth side, 205 is the fifth side, 206 is the second calibration hole, 210 is the first boss, and 220 is the second boss. DETAILED DESCRIPTION

[0033] The core of the utility model is to disclose a calibration plate to improve the accuracy of camera calibration results.

[0034] The following embodiments are described with reference to the accompanying drawings. The embodiments described below do not limit the scope of the utility model as set forth in the claims. Furthermore, the entire contents of the components described in the following embodiments are not necessarily required to provide the solutions described in the claims. It should be noted that, for ease of description, only the portions relevant to the utility model are shown in the accompanying drawings. The embodiments and features of the embodiments of the present utility model may be combined with one another unless there is a conflict.

[0035] Combine Figure 1-Figure 5 The calibration plate disclosed in the present invention includes a main plate 100 and a calibration boss 200. The main plate 100 has a reference plane. There are at least two calibration bosses 200, which are arranged parallel to the reference plane. The calibration boss 200 has a first side surface 201, a second side surface 202 and a third side surface 203. The extension directions of the first side surface 201, the second side surface 202 and the third side surface 203 are all parallel to the extension direction of the calibration boss 200, and the first side surface 201 is arranged parallel to the reference plane, and the second side surface 202 and the third side surface 203 are both arranged at an obtuse angle to the first side surface 201. The spacing distance between the first side surface 201 and the reference plane of different calibration bosses 200 is different.

[0036] Among them, the corner points of the first side 201, the second side 202 and the third side 203 of the calibration boss 200 can all provide corresponding calibration coordinates. The width and length of the reference plane are defined to extend along the X direction and the Y direction respectively, and the thickness direction of the calibration plate extends along the Z direction. Since the spacing between the first side 201 of different calibration bosses 200 and the reference plane is different, that is, the first side 201 of different calibration bosses 200 is at different positions in the Z direction, multiple sets of real data can be provided for algorithm calibration in the Z direction. The position coordinates of the calibration boss 200 on the reference plane can provide coordinate data in the X direction and the Y direction. By collecting the image data of the above-mentioned calibration plate, the camera to be calibrated can simultaneously obtain high-precision real data in the three directions of X, Y, and Z, so that the camera to be calibrated can complete high-precision calibration by scanning the above-mentioned calibration plate once.

[0037] Compared with the existing technology, the calibration plate disclosed in the present invention has calibration parameters in three dimensions, a wide range of applications, and a more comprehensive and accurate geometric model of camera imaging, which can improve the accuracy of camera calibration results. It has a simple structure, is easy to process, and has low production costs. It can be used for the calibration of dual-camera and multi-camera algorithms. At the same time, the calibration boss 200 meets the accuracy requirements required for calibration while having low processing difficulty requirements.

[0038] Furthermore, a distance marker is provided on the first side surface 201 of each calibration boss 200 to indicate the distance between the first side surface 201 and the reference surface. For example, in one embodiment, the distances between the first side surface 201 of each calibration boss 200 and the reference surface are 1 mm, 2 mm, 3 mm, and 1.5 mm, respectively, and the corresponding distance markers are 1 mm, 2 mm, 3 mm, and 1.5 mm, respectively.

[0039] The projection sizes of the first side surface 201, the second side surface 202 and the third side surface 203 of each calibration boss 200 on the reference plane can be adjusted according to the actual algorithm. Figure 2 , perpendicular to the extension direction of the calibration boss 200, the extension lengths of the first side surfaces 201 of different calibration bosses 200 vary, i.e., the values ​​of L in the figures vary. The angles between the second side surfaces 202 of different calibration bosses 200 and the reference plane may be the same or different; and the angles between the third side surfaces 203 of different calibration bosses 200 and the reference plane may be the same or different.

[0040] 3D calibration plate design is closely related to 3D data acquisition modules. For wafer AOI (Automated Optical Inspection) 3D data modules (equipment used to detect wafer surface defects), this is primarily related to the line length, depth of field, supported measurement angles, and algorithms of the module under test. In a specific embodiment disclosed in the present utility model, two of the calibration bosses 200 are defined as a first boss 210 and a second boss 220. A recognition portion 101 is provided on the main plate 100. The recognition portion 101 is separated from the first boss 210 by a first distance, and from the second boss 220 by a second distance, with the first distance being less than the second distance. The recognition portion 101 is configured to distinguish between the first boss 210 and the second boss 220, thereby distinguishing the X and Y directions of the camera and confirming the correspondence between the cameras. The first side surfaces 201 of the first boss 210 and the second boss 220 are spaced 2.5 mm and 1 mm from the reference plane, respectively, corresponding to the large and small depths of field of the module under test. The angle between the second side surface 202 and the third side surface 203 of the first and second bosses 210 and 220 and the reference plane can be 30 degrees, which is determined according to the measurement angle supported by the module to be tested. The module to be tested is 60 mm wide, which is at least twice the length of the module to be tested.

[0041] Combine Figure 4 The identification portion 101 may be a specific identification hole provided on the main body plate 100. In other embodiments, the identification portion 101 may be a boss structure, and the cross section of the boss structure is not limited to a circle or a rectangle.

[0042] The end surfaces of the calibration boss 200 along the extension direction are defined as the fourth side surface 204 and the fifth side surface 205. In some embodiments, the ends of the calibration boss 200 extend to the ends of the body plate 100, and the fourth side surface 204 and the fifth side surface 205 are arranged perpendicular to the reference plane, which is simple in structure and easy to process. In other embodiments, the calibration boss 200 is combined with the fourth side surface 204 and the fifth side surface 205 to form a plurality of calibrated portions. Figure 5 The fourth side surface 204 and the fifth side surface 205 are both arranged at an obtuse angle to the first side surface 201, so that the corner points of the fourth side surface 204 and the fifth side surface 205 can also provide calibration coordinates.

[0043] A grid structure (not shown) may be provided on part or all of the surfaces of the first side 201, the second side 202, the third side 203, the fourth side 204, and the fifth side 205 to provide more calibration coordinates through the corner points of each grid, thereby improving calibration accuracy. The shape of each grid is not limited to a rectangle or a diamond.

[0044] In one embodiment, combining Figure 4The main body plate 100 is provided with a first calibration hole 110, and / or the calibration boss 200 is provided with a second calibration hole 206. Both the first calibration hole 110 and the second calibration hole 206 are used to provide calibration coordinates. The first calibration hole 110 and the second calibration hole 206 can both be inverted conical holes, i.e., the closer to the first side surface 201, the smaller the hole diameter. The edge sharpness achieved by machining the inverted conical holes is better, and the impact on algorithm calibration is reduced.

[0045] It should be noted that the number of the first calibration holes 110 and the second calibration holes 206 is determined by the size of the main plate 100 and the calibration boss 200. The greater the number, the more feature information can be provided, and the higher the calibration accuracy obtained based on the calibration plate.

[0046] The surfaces of the main body plate 100 and the calibration boss 200 are matte-finished to prevent excessive noise and poor image quality during camera scanning.

[0047] The calibration plate is made of metal, plastic or resin. In one embodiment, the calibration plate is made of aluminum or stainless steel, which is easy to process, not easily damaged and has a long service life.

[0048] To facilitate position fixation, the main plate 100 is provided with connection holes for connection, and the end of the main plate 100 is processed into a chamfered structure 102. The calibration plate can be set within the field of view of the camera to be calibrated by screws, so that the camera can collect image data of the calibration plate.

[0049] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Specific technical means in some embodiments may be incorporated in part or in whole into another embodiment, unless expressly excluded by another embodiment. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A calibration plate, characterized in that: It comprises a main body plate (100) and a calibration boss (200), wherein the main body plate (100) has a reference surface, and there are at least two calibration bosses (200) which are arranged parallel to the reference surface; The calibration boss (200) has a first side surface (201), a second side surface (202), and a third side surface (203); the extension directions of the first side surface (201), the second side surface (202), and the third side surface (203) are all parallel to the extension direction of the calibration boss (200); the first side surface (201) is arranged parallel to the reference plane, and the second side surface (202) and the third side surface (203) are arranged at an obtuse angle to the first side surface (201); The spacing distances between the first side surfaces (201) of different calibration bosses (200) and the reference surface are different.

2. The calibration plate according to claim 1, wherein: Two of the calibration bosses (200) are a first boss (210) and a second boss (220), and an identification portion (101) is provided on the main body plate (100). The identification portion (101) is spaced apart from the first boss (210) by a first distance, and the identification portion (101) is spaced apart from the second boss (220) by a second distance, wherein the first distance is smaller than the second distance.

3. The calibration plate according to claim 2, wherein: The identification portion (101) is an identification hole opened on the main body plate (100); or, the identification portion (101) is a boss structure provided on the main body plate (100).

4. The calibration plate according to claim 1, wherein: A grid structure is provided on the surfaces of the first side surface (201), the second side surface (202) and the third side surface (203), and the corner points of each grid in the grid structure are used to provide calibration coordinates.

5. The calibration plate according to claim 1, wherein: In a direction perpendicular to the extension of the calibration boss (200), the extension lengths of the first side surfaces (201) of different calibration bosses (200) are different; The included angles between the second side surfaces (202) of different calibration bosses (200) and the reference plane are the same or different, and the included angles between the third side surfaces (203) of different calibration bosses (200) and the reference plane are the same or different.

6. The calibration plate according to claim 1, wherein: The end surfaces of the calibration boss (200) along the extension direction are respectively a fourth side surface (204) and a fifth side surface (205); The fourth side surface (204) and the fifth side surface (205) are arranged perpendicular to or at an obtuse angle to the first side surface (201).

7. The calibration plate according to claim 1, wherein: The main body plate (100) is provided with a first calibration hole (110); and / or, A second calibration hole (206) is provided on the calibration boss (200).

8. The calibration plate according to claim 1, wherein: The surfaces of the main body plate (100) and the calibration boss (200) are subjected to matte finishing; and / or, The main body plate (100) and the calibration boss (200) are made of metal, plastic or resin.

9. The calibration plate according to claim 1, wherein: The calibration boss (200) and the main body plate (100) are an integrated structure and are integrally formed.

10. The calibration plate according to claim 1, wherein: The main body plate (100) is provided with a connection hole for connection.

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