Calibration board

Abstract

The utility model discloses a calibration board, which relates to the technical field of calibration, and is characterized in that a first calibration object and a second calibration object are arranged on a calibration surface of a body of the calibration board, the first calibration object is used for providing first calibration coordinates, and the second calibration object is used for providing second calibration coordinates; and the calibration data of the first calibration coordinate and the second calibration coordinate in the direction from the body fixing surface to the body calibration surface are different. The width and the length of the calibration surface of the body are defined to extend along the X direction and the Y direction respectively, the thickness direction of the calibration plate extends along the Z direction, and the first calibration coordinate and the second calibration coordinate are located at different positions in the Z direction, so that real data can be provided for the algorithm to calibrate the Z direction; the position coordinates of the first calibration object and the second calibration object on the calibration surface of the body can provide coordinate data in the X direction and the Y direction. The camera can acquire high-precision real data in X, Y and Z directions at the same time by collecting image data of the calibration plate, and calibration is completed.

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] In order to ensure the accuracy of camera detection and measurement results, it is usually necessary to calibrate the camera. The calibration process is generally to control the camera to shoot a calibration plate with a fixed spacing pattern, and then calculate the calibration algorithm to obtain the geometric model of the camera imaging. Based on the obtained geometric model, the camera lens distortion is corrected to determine the conversion relationship between physical size and pixels.

[0004] Existing calibration plates can generally only calibrate the parameters of the camera within the two-dimensional plane, but 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 has poor accuracy, 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] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0008] A calibration plate, wherein the surface of the first side of the calibration plate is a body calibration surface, and the surface of the second side of the calibration plate is a body fixing surface for fixing;

[0009] A first calibration object and a second calibration object are arranged on the calibration surface of the main body. With the calibration surface of the main body as a reference, the first calibration object and the second calibration object extend in different directions.

[0010] Optionally, in the above-mentioned calibration plate, the first calibration object is a step structure protruding in a direction away from the fixing surface of the main body, the step structure forms a plurality of step calibration surfaces, and the step calibration surfaces have first calibration coordinates for calibration.

[0011] Optionally, in the above-mentioned calibration plate, each of the step calibration surfaces is parallel to the body calibration surface, and each of the step calibration surfaces is correspondingly provided with a distance mark for marking the distance between the step calibration surface and the body calibration surface.

[0012] Optionally, in the above calibration plate, the calibration plate is a rectangular plate-shaped structure, the first calibration object extends along the width direction of the calibration plate, and both ends extend to the end portions of the calibration plate.

[0013] Optionally, in the above-mentioned calibration plate, the second calibration object includes a plurality of conical circular holes opened on the calibration surface of the main body, the conical circular holes extend and penetrate in the direction of the fixing surface of the main body, and the small aperture end of the conical circular hole is located on the first side of the calibration plate, and the large aperture end is located on the second side of the calibration plate, and the conical circular hole has a second calibration coordinate for calibration.

[0014] Optionally, in the above calibration plate, the conical circular holes are arranged in an array; and / or,

[0015] The second calibration object is symmetrically arranged on both sides of the first calibration object.

[0016] Optionally, in the above-mentioned calibration plate, one end of the calibration surface of the body is provided with an identification feature for distinguishing the direction of the camera.

[0017] Optionally, in the above-mentioned calibration plate, the identification feature includes a plurality of groups of identifiers for identifying different quantities, each group of the identifiers includes an identified number of circular identification holes, and the circular identification holes are opened on the calibration surface of the body.

[0018] Optionally, in the above calibration plate, the surface of the calibration plate is matte treated; and / or,

[0019] The calibration plate is made of metal, plastic or resin.

[0020] Optionally, in the above-mentioned calibration plate, fixing holes for screw connection are provided on the fixing surface of the main body.

[0021] The surface of the first side of the calibration plate provided by the utility model is the body calibration surface for calibration facing the camera, and the surface of the second side is the body fixing surface for fixing with the installation base. The first calibration object and the second calibration object are arranged on the body calibration surface, the first calibration object is used to provide the first calibration coordinate, and the second calibration object is used to provide the second calibration coordinate, and the calibration data of the first calibration coordinate and the second calibration coordinate in the direction from the body fixing surface to the body calibration surface are different. The width and length of the body calibration surface are defined to extend along the X direction and the Y direction respectively, then the thickness direction of the calibration plate extends along the Z direction, and the calibration data of the first calibration coordinate and the second calibration coordinate in the direction from the body fixing surface to the body calibration surface are different, that is, the first calibration coordinate and the second calibration coordinate are at different positions in the Z direction, which can provide real data for algorithm calibration in the Z direction. The position coordinates of the first calibration object and the second calibration object on the body calibration surface can provide coordinate data in the X direction and the Y direction. The camera to be calibrated can simultaneously obtain high-precision real data in the three directions of X, Y, and Z by collecting image data of the calibration plate, so that the camera to be calibrated can complete high-precision calibration by scanning the calibration plate once.

[0022] Compared with the prior art, the calibration plate provided by the utility model has calibration parameters in three dimensions, a wide range of use, 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 cost, and can be used for the calibration of dual-camera and multi-camera algorithms. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of the first side of the calibration plate disclosed in the embodiment of the utility model;

[0025] Figure 2 It is a structural schematic diagram of the second side of the calibration plate disclosed in the embodiment of the utility model;

[0026] Figure 3 It is a side view of the calibration plate disclosed in the embodiment of the utility model.

[0027] Wherein, 100 is a calibration plate, 101 is a calibration surface of the body, and 102 is a fixing surface of the body;

[0028] 110 is a first calibration object, 120 is a second calibration object, 130 is an identification feature, and 140 is a fixing hole. DETAILED DESCRIPTION

[0029] The core of the utility model is to disclose a calibration plate to improve the accuracy of camera calibration results.

[0030] The following is an explanation of the embodiments with reference to the accompanying drawings. In addition, the embodiments shown below do not limit the contents of the utility model described in the claims. In addition, the entire contents of the construction represented by the following embodiments are not limited to those necessary as solutions to the utility model described in the claims. It should be noted that, for ease of description, only the parts related to the relevant application are shown in the accompanying drawings. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0031] Combination Figure 1 The surface of the first side of the calibration plate 100 disclosed in the embodiment of the utility model is a body calibration surface 101 for calibration facing the camera, and the surface of the second side is a body fixing surface 102 for fixing to the mounting base. A first calibration object 110 and a second calibration object 120 are arranged on the body calibration surface 101. The first calibration object 110 is used to provide a first calibration coordinate, and the second calibration object 120 is used to provide a second calibration coordinate. With the body calibration surface 101 as a reference, the extension directions of the first calibration object 110 and the second calibration object 120 are different, so that the calibration data of the first calibration coordinate and the second calibration coordinate along the body fixing surface 102 to the body calibration surface 101 are different.

[0032] Define that the width and length of the body calibration surface 101 extend along the X direction and the Y direction respectively, then the thickness direction of the calibration plate 100 (the direction from the body fixing surface 102 to the body calibration surface 101) extends along the Z direction, and the calibration data of the first calibration coordinate and the second calibration coordinate in the direction from the body fixing surface 102 to the body calibration surface 101 are different, that is, the first calibration coordinate and the second calibration coordinate are at different positions in the Z direction, which can provide real data for the algorithm calibration in the Z direction. The position coordinates of the first calibration object 110 and the second calibration object 120 on the body calibration surface 101 can provide coordinate data in the X direction and the Y direction. The camera to be calibrated can simultaneously obtain high-precision real data in the three directions of X, Y, and Z by collecting image data of the calibration plate 100, so that the camera to be calibrated can complete high-precision calibration by scanning the calibration plate 100 once.

[0033] Compared with the prior art, the calibration plate 100 disclosed in the embodiment of the utility model 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 a low production cost, and can be used for the calibration of dual-camera and multi-camera algorithms.

[0034] Combination Figure 3 In one embodiment, the first calibration object 110 is a step structure protruding in a direction away from the main body fixing surface 102, and the step structure forms a plurality of step calibration surfaces with different Z direction data, the step calibration surface has a first calibration coordinate, and different step positioning surfaces have different three-dimensional calibration coordinates, which can provide multiple sets of effective three-dimensional calibration data, and realize simpler and more efficient calibration. At the same time, the step structure meets the accuracy requirements required for calibration, and the processing difficulty requirements are relatively low.

[0035] The calibration plate 100 is used to obtain point cloud data. Figure 1 The calibration plate 100 is a rectangular plate structure, the first calibration object 110 extends along the width direction of the calibration plate 100, and both ends extend to the ends of the calibration plate 100, that is, the first calibration object 110 is arranged along the X direction to ensure that the dual camera or multi-camera combination can simultaneously scan and obtain data in the Z direction.

[0036] Furthermore, each step calibration surface is parallel to the main body calibration surface 101 , and each step calibration surface is correspondingly provided with a distance mark for marking the distance between the step calibration surface and the main body calibration surface 101 .

[0037] For example, in one embodiment, taking the plane where the main body calibration surface 101 is located as the reference plane, the distances between each step calibration surface and the main body calibration surface 101 are 1mm, 2mm, 3mm and 1.5mm respectively, and correspondingly, each distance mark is 1mm, 2mm, 3mm and 1.5mm respectively.

[0038] The first calibration object 110 may also be a block structure disposed on the body calibration surface 101 , as long as it can provide calibration data in a Z direction different from that of the body calibration surface 101 .

[0039] In a specific embodiment disclosed in the present utility model, Figure 1 and Figure 2The second calibration object 120 includes a plurality of conical circular holes that are through-opened on the calibration surface 101 of the body, that is, the second calibration object 120 extends in the direction where the fixing surface 102 of the body is located. With the calibration surface 101 of the body as a reference, the extension direction of the second calibration object 120 is opposite to that of the first calibration object 110. Specifically, the small-aperture end of the conical circular hole is located on the first side of the calibration plate 100, and the large-aperture end is located on the second side of the calibration plate 100, that is, if the calibration surface 101 of the body is the front side of the calibration plate 100 and the fixing surface 102 of the body is the back side of the calibration plate 100, then the conical circular hole is an inverted conical circular hole processed from the back side of the calibration plate 100, so as to ensure the sharpness of the edge of the conical circular hole on the calibration surface 101 of the body, thereby avoiding noise interference on the side wall of the conical circular hole, thereby affecting the accuracy of the algorithm.

[0040] The conical circular hole has a second calibration coordinate, specifically, the calibration coordinate of the conical circular hole is the coordinate of the center position of the conical circular hole on the body calibration surface 101, that is, the conical circular hole is mainly used to provide calibration data in the X and Y directions for the calibration algorithm, and it is in the same plane as the body calibration surface 101 in the Z direction, and the calibration data is the same. Compared with the prior art using a circular hole as a calibration object, the edge sharpness obtained by machining the inverted conical hole disclosed in the embodiment of the utility model is better, and the influence on the algorithm calibration is smaller.

[0041] The number of the conical holes is determined by the size of the calibration plate 100 and the conical holes. The more the number of the conical holes is, the more feature information can be provided, and the higher the calibration accuracy based on the calibration plate 100 is.

[0042] Combination Figure 1 In one embodiment, the conical circular holes are arranged in multiple rows in an array, which facilitates processing and enables the calibration plate 100 to have position information of multiple straight lines, so that the camera can obtain more comprehensive plane position information, thereby obtaining higher calibration accuracy.

[0043] During multi-camera calibration, in order to distinguish the X and Y directions of the cameras and confirm the correspondence between the cameras, an identification feature 130 is provided at one end of the body calibration surface 101 .

[0044] In one embodiment disclosed in the present utility model, the identification feature 130 includes multiple groups of identifiers for identifying different quantities, and each group of identifiers includes a circular identification hole indicating the number of the identified quantity. The circular identification hole is opened on the calibration surface 101 of the main body, and can be used to describe the posture of the calibration plate 100, thereby distinguishing the X and Y directions of the camera during multi-camera calibration, and confirming the correspondence between the cameras.

[0045] Combination Figure 1In one embodiment, each group of identifiers is arranged at one end of the main body calibration surface 101, and includes a different number of circular identification holes to represent different quantities (1, 2, 3, 4). Each group of identifiers is arranged in a regular pattern and corresponds to each column of the conical circular holes arranged in the array, and can be used to characterize different positions of the conical circular holes.

[0046] The end of one end of the calibration plate 100 may also be chamfered to serve as an identification feature 130 to describe the posture of the calibration plate 100 .

[0047] The surface of the calibration plate 100 is matte-finished to prevent the occurrence of too many noise points or poor image quality during camera scanning.

[0048] In order to facilitate fixing, a fixing hole 140 for connection is opened on the fixing surface 102 of the main body. Figure 2 The calibration plate 100 is a rectangular plate structure, and four fixing holes 140 are respectively opened at the four corners of the main body fixing surface 102. The calibration plate 100 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 100.

[0049] The calibration plate 100 may be made of metal, plastic, resin or other materials.

[0050] In one embodiment, the calibration plate 100 is made of aluminum or stainless steel, has a simple processing process, is not easily damaged, and has a long service life.

[0051] The terms "first" and "second" in the specification and claims of the present utility model are used to distinguish different objects, rather than to describe a specific order, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two.

[0052] 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. 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: The surface of the first side of the calibration plate (100) is a body calibration surface (101), and the surface of the second side is a body fixing surface (102) for fixing. A first calibration object (110) and a second calibration object (120) are arranged on the body calibration surface (101); with the body calibration surface (101) as a reference, the first calibration object (110) and the second calibration object (120) extend in different directions.

2. The calibration plate according to claim 1, characterized in that: The first calibration object (110) is a step structure protruding in a direction away from the main body fixing surface (102), the step structure forming a plurality of step calibration surfaces, and the step calibration surfaces having first calibration coordinates for calibration.

3. The calibration plate according to claim 2, characterized in that: Each of the step calibration surfaces is parallel to the main body calibration surface (101), and each of the step calibration surfaces is correspondingly provided with a distance mark for marking the distance between the step calibration surface and the main body calibration surface (101).

4. The calibration plate according to claim 2, characterized in that: The calibration plate (100) is a rectangular plate-shaped structure; the first calibration object (110) extends along the width direction of the calibration plate (100), and both ends extend to the end of the calibration plate (100).

5. The calibration plate according to claim 1, characterized in that: The second calibration object (120) comprises a plurality of conical circular holes opened on the calibration surface (101) of the main body, the conical circular holes extending in the direction of the fixing surface (102) of the main body and penetrating therethrough, and the small-diameter end of the conical circular hole is located on the first side of the calibration plate (100), and the large-diameter end is located on the second side of the calibration plate (100), and the conical circular hole has a second calibration coordinate for calibration.

6. The calibration plate according to claim 5, characterized in that: The conical circular holes are arranged in an array; and / or, The second calibration object (120) is symmetrically arranged on both sides of the first calibration object (110).

7. The calibration plate according to any one of claims 1 to 6, characterized in that: One end of the body calibration surface (101) is provided with an identification feature (130) for distinguishing the direction of the camera.

8. The calibration plate according to claim 7, characterized in that: The identification feature (130) includes a plurality of groups of identifiers for identifying different quantities, each group of the identifiers includes an identified number of circular identification holes, and the circular identification holes are opened on the body calibration surface (101).

9. The calibration plate according to any one of claims 1 to 6, characterized in that: The surface of the calibration plate (100) is subjected to matte treatment; and / or, The calibration plate (100) is made of metal, plastic or resin.

10. The calibration plate according to any one of claims 1 to 6, characterized in that: The main body fixing surface (102) is provided with a fixing hole (140) for screw connection.

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