Calibration method, device and equipment of attitude measurement camera coordinate system and storage medium

Abstract

The invention provides an attitude measurement camera coordinate system calibration method, apparatus and device, and a storage medium, which can be applied to the technical field of measurement calibration. The method comprises the steps that a calibration plate is constructed, a conversion target seat and at least one reflective mark point are arranged on the calibration plate, the conversion target seat is used for placing a cube-corner prism target ball and a photogrammetry target ball, the cube-corner prism target ball and the photogrammetry target ball are the same in diameter, and the calibration plate is placed at different positions in a view field of an attitude measurement camera; the method comprises the following steps: acquiring three-dimensional coordinates of a cube-corner prism target ball by using a laser tracker, replacing a photogrammetric target ball, shooting an image of a calibration plate by using an attitude measurement camera to obtain the three-dimensional coordinates and a plurality of images of the cube-corner prism target ball in a laser tracker coordinate system, and calculating the three-dimensional coordinates of the cube-corner prism target ball according to the three-dimensional coordinates and the plurality of images of the cube-corner prism target ball in the laser tracker coordinate system. And calibrating a coordinate system of the attitude measurement camera. The extraction precision of the two-dimensional image coordinates of the target spot can be improved, and then the calibration precision of the coordinate system is improved.

Description

Technical Field

[0001] The present invention relates to the field of measurement and calibration, and in particular to a calibration method, device, equipment and storage medium for a posture measurement camera coordinate system. Background Art

[0002] In modern precision engineering measurement, three-degree-of-freedom laser trackers, using laser interferometry, can quickly acquire high-precision three-dimensional coordinate information of a target. These trackers offer advantages such as high measurement accuracy, a large measurement range, and excellent dynamic performance, making them widely used in high-end manufacturing and large-scale scientific engineering. Six-degree-of-freedom laser instruments, based on three-degree-of-freedom laser trackers, combine visual measurement technology to achieve high-precision measurement of target pose parameters. These instruments are widely used in large-scale equipment manufacturing, such as aerospace, energy machinery, and large scientific facilities. Therefore, to obtain high-precision pose information, it is necessary to unify the coordinate system of the laser tracker with that of the pose measurement camera.

[0003] Currently, there are relatively few manufacturers of six-degree-of-freedom laser trackers in China, and the content related to the calibration method of the laser tracker and the attitude measurement camera coordinate system is also very limited. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method, apparatus, device and storage medium for calibrating a coordinate system of a posture measurement camera.

[0005] According to a first aspect of the present invention, a calibration method for a posture measurement camera coordinate system is provided, comprising:

[0006] Construct a calibration plate, wherein a conversion target base and at least one reflective marking point are provided on the calibration plate, wherein the conversion target base is used to place a corner cube prism target sphere and a photogrammetry target sphere, wherein the corner cube prism target sphere and the photogrammetry target sphere have the same diameter;

[0007] Placing the calibration plate at multiple different positions within the field of view of the attitude measurement camera;

[0008] At the plurality of different positions, a laser tracker is used to measure the three-dimensional coordinates of the corner cube target sphere in the laser tracker coordinate system, and the corner cube target sphere is placed on the conversion target seat of the calibration plate;

[0009] At the plurality of different positions, the attitude measurement camera is used to capture images of the calibration plate to obtain a plurality of images, and the photogrammetry target sphere is placed on the conversion target seat of the calibration plate;

[0010] The posture measurement camera coordinate system is calibrated according to the three-dimensional coordinates of the corner cube target in the laser tracker coordinate system and the multiple images.

[0011] In some embodiments, the method further comprises:

[0012] placing the photogrammetry target sphere on the conversion target mount;

[0013] The photogrammetry system is used to calculate the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, and the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system.

[0014] In some embodiments, calibrating the attitude measurement camera coordinate system according to the three-dimensional coordinates of the corner cube target in the laser tracker coordinate system and the multiple images includes:

[0015] Based on the multiple images, calculating the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere;

[0016] Calculate the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system based on the three-dimensional coordinates of the center of the reflective mark point on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere;

[0017] The attitude measurement camera coordinate system is calibrated according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system.

[0018] In some embodiments, calculating the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system based on the three-dimensional coordinates of the center of the reflective mark point on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere includes:

[0019] Calculate the extrinsic parameter matrix of the attitude measurement camera coordinate system based on the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere;

[0020] The three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system are calculated according to the extrinsic parameter matrix of the attitude measurement camera coordinate system.

[0021] In some embodiments, calibrating the attitude measurement camera coordinate system according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system includes:

[0022] Calculate the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system;

[0023] The attitude measurement camera coordinate system is calibrated according to a conversion matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

[0024] In some embodiments, the method further comprises:

[0025] The singular value decomposition method is used to solve the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

[0026] In some embodiments, the calculating the external parameter matrix of the attitude measurement camera coordinate system according to the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere includes:

[0027] The three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere are used as inputs of the EPnP algorithm to calculate the extrinsic parameter matrix of the attitude measurement camera coordinate system.

[0028] A second aspect of the present invention provides a calibration device for a posture measurement camera coordinate system, comprising:

[0029] A calibration plate, wherein a conversion target seat and at least one reflective marking point are provided on the calibration plate, wherein the conversion target seat is used to place a corner cube prism target sphere and a photogrammetry target sphere, wherein the corner cube prism target sphere and the photogrammetry target sphere have the same diameter;

[0030] a laser tracker for measuring the three-dimensional coordinates of the corner cube target sphere in a laser tracker coordinate system at a plurality of different positions when the calibration plate is placed at the plurality of different positions within the field of view of the attitude measurement camera, wherein the corner cube target sphere is placed on a conversion target holder of the calibration plate;

[0031] An attitude measurement camera is configured to capture images of the calibration plate at multiple different positions within the field of view of the attitude measurement camera, thereby obtaining multiple images. The photogrammetry target sphere is placed on a conversion target holder of the calibration plate.

[0032] A calculation module is used to calibrate the posture measurement camera coordinate system according to the three-dimensional coordinates of the corner cube prism target in the laser tracker coordinate system and the multiple images.

[0033] The third aspect of the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the above method.

[0034] A fourth aspect of the present invention further provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, causes the processor to execute the above method.

[0035] The method, apparatus, equipment, and medium for calibrating the coordinate system of a posture measurement camera provided by the present invention are based on the principle that a photographic target sphere and a corner cube prism target sphere of the same diameter are concentric. Taking into account the disadvantage of the poor imaging quality of the corner cube prism target sphere in the image, the high-quality imaging of the photogrammetric target sphere is utilized, and the corner cube prism target sphere and the photogrammetric target sphere are alternately used to improve the extraction accuracy of the two-dimensional pixel coordinates of the target point. On the one hand, this method has a simple measurement process and high measurement accuracy, which can meet the accuracy requirements of the posture measurement of a six-degree-of-freedom laser tracker. On the other hand, it is applicable to the coordinate system of a multi-sensor system in which most laser sensors are combined with cameras, meeting the posture measurement accuracy of the multi-sensor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0037] Figure 1 The flowchart of the method for calibrating the coordinate system of a posture measurement camera according to an embodiment of the present invention is schematically shown;

[0038] Figure 2 A schematic diagram of calibrating a camera coordinate system for attitude measurement according to an embodiment of the present invention is shown schematically;

[0039] Figure 3 The structure block diagram of the device for calibrating the coordinate system of a posture measurement camera according to an embodiment of the present invention is schematically shown;

[0040] Figure 4Schematically shows a block diagram of an electronic device suitable for implementing a calibration method for a camera coordinate system for attitude measurement according to an embodiment of the present invention;

[0041] Description of reference numerals:

[0042] 1-Laser tracker coordinate system, 2-Attitude measurement camera coordinate system, 3-Photogrammetry system coordinate system, 4-Image coordinate system, 5-Camera imaging plane, 6-Calibration plate, 7-Reflective marker point, 8-Transformation target. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0044] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0045] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0046] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0047] Figure 1 The flowchart of the method for calibrating the coordinate system of a posture measurement camera according to an embodiment of the present invention is schematically shown.

[0048] like Figure 1 As shown, the calibration method of the attitude measurement camera coordinate system of this embodiment includes operations S110 to S140.

[0049] In operation S110, a calibration plate 6 is constructed. A conversion target base 8 and at least one reflective marking point 7 are provided on the calibration plate 6. The conversion target base 8 is used to place a corner cube prism target sphere and a photogrammetry target sphere. The corner cube prism target sphere and the photogrammetry target sphere have the same diameter.

[0050] In operation S120 , the calibration plate 6 is placed at a plurality of different positions within the field of view of the attitude measurement camera.

[0051] In operation S130 , a laser tracker is used to measure the three-dimensional coordinates of the corner cube target sphere in the laser tracker coordinate system at multiple different positions. The corner cube target sphere is placed on the conversion target holder 8 of the calibration plate 6 .

[0052] In operation S140 , the image of the calibration plate is captured at multiple different positions using a posture measurement camera to obtain multiple images, and a photogrammetry target sphere is placed on the conversion target holder 8 of the calibration plate 6 .

[0053] In operation S150 , the attitude measurement camera coordinate system 2 is calibrated according to the three-dimensional coordinates of the corner cube target in the laser tracker coordinate system and the multiple images.

[0054] In one embodiment of the present invention, before operation S120, the calibration method of the attitude measurement camera coordinate system also includes: placing the photogrammetric target sphere on the conversion target base 8; using the photogrammetric system to calculate the three-dimensional coordinates of the center of the reflective mark point 7 in the calibration plate 7 in the photogrammetric system coordinate system 3, and the three-dimensional coordinates of the center of the photogrammetric target sphere in the photogrammetric system coordinate system 3.

[0055] In one embodiment of the present invention, the above-mentioned calibration of the attitude measurement camera coordinate system 2 based on the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system and multiple images includes: calculating the two-dimensional pixel coordinates of the center of the reflective mark point 7 on the calibration plate 6 and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere based on the multiple images; calculating the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the attitude measurement camera coordinate system 2 according to the three-dimensional coordinates of the center of the reflective mark point 7 in the calibration plate 6 in the photogrammetry system coordinate system 3, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system 3, the two-dimensional pixel coordinates of the center of the reflective mark point 7 on the calibration plate 6, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere; calibrating the attitude measurement camera coordinate system 2 according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the attitude measurement camera coordinate system 2 and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system 1.

[0056] In one embodiment of the present invention, the above-mentioned calculation of the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the posture measurement camera coordinate system 2 according to the three-dimensional coordinates of the center of the reflective mark point 7 in the calibration plate 6 in the photogrammetry system coordinate system 3, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system 3, the two-dimensional pixel coordinates of the center of the reflective mark point 7 on the calibration plate 6, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere includes: calculating the extrinsic parameter matrix of the posture measurement camera coordinate system 2 according to the three-dimensional coordinates of the center of the reflective mark point 7 in the calibration plate 6 in the photogrammetry system coordinate system 3, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system 3, the two-dimensional pixel coordinates of the center of the reflective mark point 7 on the calibration plate 6, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere; and calculating the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the posture measurement camera coordinate system 2 according to the extrinsic parameter matrix of the posture measurement camera coordinate system 2.

[0057] In one embodiment of the present invention, the above-mentioned calibration of the attitude measurement camera coordinate system 2 based on the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the attitude measurement camera coordinate system 2 and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system 1 includes: calculating the transformation matrix between the laser tracker coordinate system 1 and the attitude measurement camera coordinate system 2 based on the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate 6 in the attitude measurement camera coordinate system 2 and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system 1; and calibrating the attitude measurement camera coordinate system 2 based on the transformation matrix between the laser tracker coordinate system 1 and the attitude measurement camera coordinate system 2.

[0058] In one embodiment of the present invention, the singular value decomposition method can be used to solve the transformation matrix between the laser tracker coordinate system 1 and the attitude measurement camera coordinate system 2 .

[0059] In one embodiment of the present invention, the three-dimensional coordinates of the center of the reflective mark point 7 in the calibration plate 6 in the photogrammetry system coordinate system 3, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system 3, the two-dimensional pixel coordinates of the center of the reflective mark point 7 on the calibration plate 6, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere can be used as inputs of the EPnP algorithm to calculate the external parameter matrix of the attitude measurement camera coordinate system 2.

[0060] An embodiment of the present invention further provides a method for calibrating a coordinate system of a posture measurement camera, which includes operations S1-S6.

[0061] In operation S1 , a calibration plate 6 is constructed. The calibration plate includes a conversion target base 8 and at least one circular reflective marking point 7 . Corner cube prism target spheres and photogrammetry target spheres of the same diameter can be alternately placed on the conversion target base 8 .

[0062] In operation S2, the photogrammetric target ball is placed on the conversion target base 8, and the photogrammetric system is used to calculate the three-dimensional coordinates R (x wi ,y wi , z wi )(i=1,2,...n) and the three-dimensional coordinates P(x w ,y w , z w ).

[0063] Here, i represents the serial number of the reflective marker point 7. In this embodiment, the photogrammetry system coordinate system is used as the world coordinate system in the calculation.

[0064] In operation S3: the calibration plate 6 is placed at m different positions in the field of view of the attitude measurement camera. First, the corner cube prism target ball is placed on the conversion target base 8, and the three-dimensional coordinates P (x Lj ,y Lj , z Lj )(j=1,2,...m), where j represents the jth position of the calibration plate 6; the corner cube prism target is replaced by a photogrammetry target, and m images of the calibration plate 6 are taken by a posture measurement camera, each image is consistent with P(x Lj ,y Lj , z Lj ) one-to-one correspondence, image coordinate system 4 see Figure 2 shown.

[0065] Among them, Figure 2 As shown, the center Oc of the attitude measurement camera coordinate system 2, the imaging center p of the camera imaging plane 5 of the attitude measurement camera and the center of the photogrammetry target sphere on the conversion target base 8 are on a straight line.

[0066] In operation S4, the m images collected in operation S3 are processed to calculate the two-dimensional pixel coordinates r (u ij , v ij )(i=1,2,...n,j=1,2,...m) and the two-dimensional pixel coordinates p(u j , v j )(j=1,2,...m).

[0067] In operation S5, the three-dimensional coordinates R (x) of the reflective mark point 7 on the calibration plate 6 and the photogrammetry target sphere obtained in operation S1 in the world coordinate system (i.e., the photogrammetry system coordinate system 3) are converted into wi ,y wi , z wi)(i=1,2,...n) and P(x w ,y w , z w ), and the two-dimensional pixel coordinates r(u of the reflective marker 7 on the calibration plate 6 and the photogrammetry target sphere calculated in operation S4 ij , v ij )(i=1,2,…n,j=1,2,…m) and p(u j ,vj)(j=1,2,...m) is used as the input of EPnP algorithm to calculate the external parameter matrix of the attitude measurement camera coordinate system, and then obtain the three-dimensional coordinates P(x Cj ,y Cj , z Cj )(j=1,2,...m).

[0068] In operation S6, the three-dimensional coordinates P (x Cj ,y Cj , z Cj )(j=1,2,...m) and the three-dimensional coordinates P(x Lj ,y Lj , z Lj )(j=1,2,...m), where j represents the jth position of the calibration plate. The transformation matrix between the laser tracker coordinate system 1 and the attitude measurement camera coordinate system 2 can be calculated as:

[0069]

[0070] in, is the rotation matrix between the attitude measurement camera coordinate system 2 and the laser tracker coordinate system 1; is the translation vector; is the coordinate vector of the center P of the corner cube target sphere in the laser tracker coordinate system 1; is the coordinate vector of the center P of the photogrammetry target sphere in the attitude measurement camera coordinate system 2.

[0071] Furthermore, the singular value decomposition method can be used to solve the transformation matrix of the two coordinate systems.

[0072] Minimization formula is as follows:

[0073]

[0074] in, and It represents the three-dimensional coordinates of the center of the corner cube prism target in the laser tracker coordinate system 1 and the three-dimensional coordinates of the center of the photogrammetry target in the attitude measurement camera coordinate system 2 when the calibration plate 6 is at the jth position, j=1, 2, ...m.

[0075] First, we need to calculate the coordinates of the center of the corner cube target sphere under the laser tracker coordinate 1 Center of Gravity And the matrix A after removing the center of gravity:

[0076]

[0077]

[0078] Then calculate the coordinates of the center of the photogrammetry target sphere in the attitude measurement camera coordinate system 2 Center of Gravity And the matrix B after removing the center of gravity:

[0079]

[0080]

[0081] Let matrix H = B T A, perform SVD decomposition on the matrix H:

[0082] U∑V T =SVD(H) Formula (7)

[0083] When H is full rank, there is a unique solution, and the rotation matrix R can be obtained:

[0084]

[0085] The translation vector T is:

[0086]

[0087] Based on the above-mentioned calibration method of the camera coordinate system for attitude measurement, the present invention also provides a calibration device for the camera coordinate system for attitude measurement. Figure 3 The device is described in detail.

[0088] Figure 3 The structure block diagram of the device for calibrating the coordinate system of a posture measurement camera according to an embodiment of the present invention is schematically shown.

[0089] like Figure 3 As shown, the calibration device 300 of the attitude measurement camera coordinate system of this embodiment includes a calibration plate 310 , a laser tracker 320 , an attitude measurement camera 330 and a calculation module 340 .

[0090] The calibration plate 310 is provided with a conversion target base and at least one reflective mark point. The conversion target base is used to place a corner cube prism target sphere and a photogrammetry target sphere. The corner cube prism target sphere and the photogrammetry target sphere have the same diameter.

[0091] The laser tracker 320 is configured to measure the three-dimensional coordinates of the corner cube target sphere in the laser tracker coordinate system at the plurality of different positions when the calibration plate is placed at the plurality of different positions within the field of view of the attitude measurement camera, wherein the corner cube target sphere is placed on a conversion target holder of the calibration plate;

[0092] The attitude measurement camera 330 is used to capture images of the calibration plate at multiple different positions within the field of view of the attitude measurement camera, thereby obtaining multiple images. A photogrammetry target sphere is placed on the conversion target holder of the calibration plate.

[0093] The calculation module 340 is used to calibrate the attitude measurement camera coordinate system based on the three-dimensional coordinates of the corner cube prism target in the laser tracker coordinate system and multiple images.

[0094] According to an embodiment of the present invention, the calibration device 300 for the attitude measurement camera coordinate system further includes:

[0095] A placement module, used for placing the photogrammetry target sphere on the conversion target mount;

[0096] The three-dimensional coordinate calculation module is used to calculate the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, and the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system using the photogrammetry system.

[0097] According to an embodiment of the present invention, calibrating the attitude measurement camera coordinate system based on the three-dimensional coordinates and multiple images of the corner cube target in the laser tracker coordinate system includes:

[0098] Based on multiple images, calculate the 2D pixel coordinates of the center of the reflective marker on the calibration plate and the 2D pixel coordinates of the center of the photogrammetry target sphere;

[0099] Calculate the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the photogrammetry camera coordinate system based on the three-dimensional coordinates of the center of the reflective marker on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective marker on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere;

[0100] The attitude measurement camera coordinate system is calibrated according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system.

[0101] According to an embodiment of the present invention, calculating the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the coordinate system of the attitude measurement camera according to the three-dimensional coordinates of the center of the reflective mark point on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere includes:

[0102] According to the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere, the external parameter matrix of the attitude measurement camera coordinate system is calculated;

[0103] According to the external parameter matrix of the attitude measurement camera coordinate system, the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system are calculated.

[0104] According to an embodiment of the present invention, calibrating the attitude measurement camera coordinate system includes:

[0105] Calculate the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system based on the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system;

[0106] The attitude measurement camera coordinate system is calibrated according to the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

[0107] According to an embodiment of the present invention, a singular value decomposition method is used to solve the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

[0108] According to an embodiment of the present invention, the extrinsic parameter matrix of the attitude measurement camera coordinate system is calculated based on the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere.

[0109] The three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere are used as inputs of the EPnP algorithm to calculate the extrinsic parameter matrix of the attitude measurement camera coordinate system.

[0110] According to an embodiment of the present invention, the above modules can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present invention, at least one of the above modules can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation modes of software, hardware and firmware or in a suitable combination of any of them. Alternatively, at least one of the above modules can be at least partially implemented as a computer program module, which can execute the corresponding function when the computer program module is run.

[0111] Figure 4 A block diagram schematically shows an electronic device for a method for calibrating a coordinate system of a posture measurement camera according to an embodiment of the present invention.

[0112] like Figure 4 As shown, the electronic device 400 according to an embodiment of the present invention includes a processor 401, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 402 or a program loaded from a storage portion 408 into a random access memory (RAM) 403. The processor 401 may, for example, include a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a dedicated microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 401 may also include an onboard memory for caching purposes. The processor 401 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0113] Various programs and data required for the operation of the electronic device 400 are stored in the RAM 403. The processor 401, ROM 402, and RAM 403 are connected to each other via a bus 404. The processor 401 executes the programs in the ROM 402 and / or RAM 403 to perform various operations according to the method flow of the embodiment of the present invention. It should be noted that the programs may also be stored in one or more memories other than the ROM 402 and RAM 403. The processor 401 may also execute the programs stored in the one or more memories to perform various operations according to the method flow of the embodiment of the present invention.

[0114] According to an embodiment of the present invention, electronic device 400 may further include an input / output (I / O) interface 405, which is also connected to bus 404. Electronic device 400 may further include one or more of the following components connected to I / O interface 405: an input section 406 including a keyboard, a mouse, etc.; an output section 407 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and speakers; a storage section 408 including a hard disk; and a communication section 409 including a network interface card such as a LAN card or a modem. Communication section 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to I / O interface 405 as needed. Removable media 411, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed in drive 410 as needed, so that computer programs read from the removable media can be installed into storage section 408 as needed.

[0115] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments, or may exist independently and not incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present invention.

[0116] According to an embodiment of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as, but not limited to, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in combination with an instruction execution system, apparatus, or device. For example, according to an embodiment of the present invention, a computer-readable storage medium may include the ROM 402 and / or RAM 403 described above and / or one or more memories other than ROM 402 and RAM 403.

[0117] The embodiments of the present invention further include a computer program product, which includes a computer program containing program code for executing the method shown in the flowchart. When the computer program product is run in a computer system, the program code is used to cause the computer system to implement the method provided by the embodiments of the present invention.

[0118] The computer program executes the above functions defined in the system / device of the embodiment of the present invention when the computer program is executed by the processor 401. According to the embodiment of the present invention, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0119] In one embodiment, the computer program may be stored on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may be transmitted and distributed in the form of a signal on a network medium, downloaded and installed via the communication portion 409, and / or installed from a removable medium 411. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to wireless, wired, or any suitable combination thereof.

[0120] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 409 and / or installed from the removable medium 411. When the computer program is executed by the processor 401, the above-described functions defined in the system of the embodiment of the present invention are performed. According to the embodiment of the present invention, the systems, devices, means, modules, units, etc. described above can be implemented by computer program modules.

[0121] According to an embodiment of the present invention, the program code for executing the computer program provided by the embodiment of the present invention can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, Python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (e.g., using an Internet service provider to connect via the Internet).

[0122] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0123] Those skilled in the art will appreciate that various combinations and / or combinations of features described in the various embodiments and / or claims of the present invention may be made, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, various combinations and / or combinations of features described in the various embodiments and / or claims of the present invention may be made, without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0124] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for calibrating a camera coordinate system for attitude measurement, characterized in that: include: Construct a calibration plate, wherein a conversion target base and at least one reflective marking point are provided on the calibration plate, wherein the conversion target base is used to place a corner cube prism target sphere and a photogrammetry target sphere, wherein the corner cube prism target sphere and the photogrammetry target sphere have the same diameter; Placing the calibration plate at multiple different positions within the field of view of the attitude measurement camera; At the plurality of different positions, a laser tracker is used to measure the three-dimensional coordinates of the corner cube target sphere in the laser tracker coordinate system, and the corner cube target sphere is placed on the conversion target seat of the calibration plate; At the plurality of different positions, the attitude measurement camera is used to capture images of the calibration plate to obtain a plurality of images, and the photogrammetry target sphere is placed on the conversion target seat of the calibration plate; The posture measurement camera coordinate system is calibrated according to the three-dimensional coordinates of the corner cube target in the laser tracker coordinate system and the multiple images.

2. The method for calibrating the coordinate system of a posture measurement camera according to claim 1, wherein: The method further comprises: placing the photogrammetry target sphere on the conversion target mount; The photogrammetry system is used to calculate the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, and the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system.

3. The method for calibrating the coordinate system of a posture measurement camera according to claim 2, wherein: The calibrating the attitude measurement camera coordinate system according to the three-dimensional coordinates of the corner cube target in the laser tracker coordinate system and the multiple images includes: Based on the multiple images, calculating the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere; Calculate the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system based on the three-dimensional coordinates of the center of the reflective mark point on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere; The attitude measurement camera coordinate system is calibrated according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system.

4. The method for calibrating the coordinate system of a posture measurement camera according to claim 3, wherein: Calculating the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system according to the three-dimensional coordinates of the center of the reflective mark point on the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere includes: Calculate the extrinsic parameter matrix of the attitude measurement camera coordinate system based on the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere; The three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system are calculated according to the extrinsic parameter matrix of the attitude measurement camera coordinate system.

5. The method for calibrating the coordinate system of a posture measurement camera according to claim 3, wherein: The calibrating the attitude measurement camera coordinate system according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system comprises: Calculate the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system according to the three-dimensional coordinates of the photogrammetry target sphere on the calibration plate in the attitude measurement camera coordinate system and the three-dimensional coordinates of the corner cube prism target sphere in the laser tracker coordinate system; The attitude measurement camera coordinate system is calibrated according to a conversion matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

6. The method for calibrating the coordinate system of a posture measurement camera according to claim 5, wherein: The method further comprises: The singular value decomposition method is used to solve the transformation matrix between the laser tracker coordinate system and the attitude measurement camera coordinate system.

7. The method for calibrating the coordinate system of a posture measurement camera according to claim 4, wherein: The extrinsic parameter matrix of the attitude measurement camera coordinate system is calculated based on the three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere, including: The three-dimensional coordinates of the center of the reflective mark point in the calibration plate in the photogrammetry system coordinate system, the three-dimensional coordinates of the center of the photogrammetry target sphere in the photogrammetry system coordinate system, the two-dimensional pixel coordinates of the center of the reflective mark point on the calibration plate, and the two-dimensional pixel coordinates of the center of the photogrammetry target sphere are used as inputs of the EPnP algorithm to calculate the extrinsic parameter matrix of the attitude measurement camera coordinate system.

8. A calibration device for a camera coordinate system for attitude measurement, characterized in that: include: A calibration plate, wherein a conversion target seat and at least one reflective marking point are provided on the calibration plate, wherein the conversion target seat is used to place a corner cube prism target sphere and a photogrammetry target sphere, wherein the corner cube prism target sphere and the photogrammetry target sphere have the same diameter; a laser tracker for measuring the three-dimensional coordinates of the corner cube target sphere in a laser tracker coordinate system at a plurality of different positions when the calibration plate is placed at the plurality of different positions within the field of view of the attitude measurement camera, wherein the corner cube target sphere is placed on a conversion target holder of the calibration plate; An attitude measurement camera is configured to capture images of the calibration plate at multiple different positions within the field of view of the attitude measurement camera, thereby obtaining multiple images. The photogrammetry target sphere is placed on a conversion target holder of the calibration plate. A calculation module is used to calibrate the posture measurement camera coordinate system according to the three-dimensional coordinates of the corner cube prism target in the laser tracker coordinate system and the multiple images.

9. An electronic device, characterized in that: include: one or more processors; as well as a storage device for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors are enabled to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that Executable instructions are stored thereon, and when the instructions are executed by a processor, the processor is caused to execute the method according to any one of claims 1 to 7.

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