A large-size structure laser three-dimensional scanning method and device based on multi-station fusion

Abstract

The application provides a large-size structure laser three-dimensional scanning method and device based on multi-station fusion, comprising: constructing multiple standard devices, selecting no less than four mark points on each standard device; dividing the measured large-size structure into multiple measured areas, obtaining the coordinates of the multiple standard devices under the global coordinate system through a scanning device; taking the calibration coordinate values of the mark points under the standard device coordinate system as the reference values, fitting the measured coordinate values under the global coordinate system, and obtaining the corrected coordinate values of the mark points on the Nth standard device under the global coordinate system; obtaining the point cloud matrix of the measured large-size structure and the standard device coordinate values under the scanner coordinate system respectively; based on the corrected coordinate values of the mark points on the Nth standard device under the global coordinate system and the coordinate values under the scanner coordinate system, converting the point cloud matrix D BN into the point cloud matrix D CN under the global coordinate system; and fusing the point cloud matrix D CN together to form the final point cloud matrix of the measured product.

Description

Technical Field

[0001] This application relates to the field of industrial large-size measurement technology, and more specifically, to a method and apparatus for laser three-dimensional scanning of large-size structures based on multi-station fusion. Background Technology

[0002] When performing 3D scanning of large and complex structures, it is necessary to place the laser 3D scanner at different locations and scan from different perspectives. The point clouds obtained from each station are then stitched together to form the overall point cloud of the structure under test. During the stitching of point clouds from different stations, station errors can lead to discontinuities such as breaks and twists in the overlapping areas of the point clouds between different stations.

[0003] Current multi-station laser 3D scanning point cloud stitching methods only focus on local accuracy or global coherence, and cannot achieve both simultaneously. Summary of the Invention

[0004] The purpose of this application is to provide a method and apparatus for large-size structure laser three-dimensional scanning based on multi-station fusion, which solves at least one of the technical problems mentioned above. The specific solution is as follows:

[0005] According to a specific embodiment of this application, this application provides a large-size structure laser three-dimensional scanning method based on multi-station fusion, including:

[0006] Construct multiple standard instruments, and select no fewer than four marker points on each standard instrument, denoted as N1-Ni. The marker points of the Nth standard instrument are located in the standard instrument coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4;

[0007] The large structure to be measured is divided into multiple test areas, and multiple standard instruments are respectively set in the multiple test areas. The coordinates of the multiple standard instruments in the global coordinate system X are obtained by scanning equipment. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi ZCNi );

[0008] Using the aforementioned marker points in the standard coordinate system X A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );

[0009] At different stations, the large-sized structure under test and multiple standard instruments are scanned simultaneously. The results are recorded in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi );

[0010] Based on the marker point on the Nth standard in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ;

[0011] In the global coordinate system X C YC Z C Below, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product.

[0012] In some embodiments, the reference points are positioned in the standard coordinate system X. A Y A Z A The coordinates below are used as the reference values, and their values ​​are used in relation to the global coordinate system X. C Y C Z C By fitting the lower coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ),include:

[0013] Let the global coordinate system X C Y C Z C To the standard coordinate system X A Y A Z A The transformation matrix is ​​R CAN The translation vector is T CAN Then we obtain the global coordinate system X. C Y C Z C Lower measurement coordinate values ​​(X) CNi ,Y CNi Z CNi In the standard coordinate system X A Y A Z A Transformed coordinates (X′) ACNi ,Y′ ACNi ,Z′ ACNi )for:

[0014]

[0015] In the standard coordinate system X A Y A Z A Next, construct a distance equation between the transformed coordinates and calibration coordinates of the Nth standard feature point, and construct an objective function based on the distance minimization criterion:

[0016] M is a natural number greater than or equal to 4;

[0017] Place each of the marker points on each of the aforementioned standards in the standard coordinate system X. A Y A Z A The calibration coordinates below and the global coordinate system X C Y C Z C Substituting the measured coordinate values ​​into formula (2), the transformation matrix R is obtained through minimum value iterative search. CAN Translation vector T CAN ;

[0018] Based on formula (1), and according to the coordinates of each of the aforementioned marker points in the standard coordinate system X... A Y A Z A The calibration coordinates are used to calculate the position of the marker point on the Nth standard in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ).

[0019] In some embodiments, the marker point based on the Nth standard is located in the global coordinate system X. C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ,include:

[0020] Let the scanner coordinate system be X. B Y B Z B To the global coordinate system X C Y C Z C The transformation matrix is ​​R BCN Translation vector T BCN Then the scanner coordinate system X is obtained. B Y BZ B Lower coordinate value (X) BNi ,Y BNi Z BNi In the global coordinate system X C Y C Z C Lower coordinate value (X) CNi ,Y CNi Z CNi )for:

[0021]

[0022] Place the marker point on the standard in the global coordinate system X. C Y C Z C Corrected coordinates (X) ACNi ,Y ACNi Z ACNi ), and the marker point in the scanner coordinate system X B Y B Z B The coordinates below (X) BNi ,Y BNi Z BNi Substituting into formula (3), the transformation matrix R can be calculated. BCN Translation vector T BCN ;

[0023] According to the transformation matrix R BCN Translation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN .

[0024] In some embodiments, the transformation matrix R BCN Translation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN ,include:

[0025] According to the transformation matrix R BCN Translation vector T BCN The scanned point cloud matrix D is calculated using the following formula (4). BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN

[0026] D CN =R BCN D BN +T BCN (4).

[0027] In some embodiments, the construction of multiple standards includes:

[0028] The standard size is constructed based on the longest dimension of the large-size structure being tested, such that the longest dimension of the standard is 1 / 3 to 1 / 4 of the longest dimension of the large-size structure being tested.

[0029] In some embodiments, not all of the marker points on each of the standards are on the same straight line.

[0030] In some embodiments, at least one face of the standard is a square, and there are four marker points located at the four corners of the square.

[0031] This application also provides a large-size structure laser 3D scanning device based on multi-station fusion, including:

[0032] A construction unit is used to construct multiple standards. At least four marker points, denoted as N1-Ni, are selected on each standard. The marker points of the Nth standard are located in the standard coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4;

[0033] The acquisition unit is used to divide the large-sized structure to be measured into multiple measurement regions, set multiple standards in the multiple measurement regions respectively, and obtain the coordinates of the multiple standards in the global coordinate system X by a scanning device. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi );

[0034] Fitting unit, used to fit each of the said marker points in the standard coordinate system XA Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );

[0035] The scanning unit is used to simultaneously scan the large-sized structure under test and multiple standards from different stations, in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi );

[0036] Transformation unit, used to transform the marker point on the Nth standard in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ;

[0037] Fusion unit, used in global coordinate system X C Y C Z C Below, the point cloud matrix D obtained from each station is transformed.CN They are combined to form the final point cloud matrix of the tested product.

[0038] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in any of the preceding claims.

[0039] This application also provides an electronic device, including:

[0040] One or more processors;

[0041] A storage device for storing one or more programs, which, when executed by the one or more processors, cause the one or more processors to perform the method as described in any of the preceding methods.

[0042] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects:

[0043] The point cloud stitching method proposed in this application arranges multiple standard markers with common marker points in the space where the product under test is located. Firstly, the coordinates of the marker points on the standard markers in the standard marker coordinate system are pre-calibrated. Secondly, large-scale measuring equipment (such as laser trackers, total stations, and lidar) is used to measure the coordinates of all common points on the standard markers in a unified coordinate system. Since the measurement error of large-scale measuring equipment increases with distance, it can lead to large measurement errors for distant target points, affecting the scanning stitching. Therefore, the positions in the global coordinate system are first calibrated based on the relationship between the marker points on the standard markers themselves, obtaining calibrated coordinates in the unified coordinate system. When scanning the product under test using a laser 3D scanning device at different stations, the common marker points on the standard markers are scanned simultaneously. The scanned point cloud is transferred to the unified coordinate system using the coordinates of the common points on the calibrated standard markers. Based on this method, the continuity between point clouds at different stations is ensured, while also maintaining the accuracy of local scanned point cloud transformation. Attached Figure Description

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0045] Figure 1 Flowchart of the large-size structure laser 3D scanning method based on multi-station fusion provided in this application;

[0046] Figure 2 A schematic diagram of a large-size structure laser 3D scanning system based on multi-station fusion provided for this application;

[0047] Figure 3 A schematic diagram of the structure of the large-size laser 3D scanning device based on multi-station fusion provided in this application;

[0048] Figure 4 A schematic diagram of the electronic device structure provided in this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0051] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0052] It should be understood that although the terms first, second, third, etc., may be used in the embodiments of this application, these descriptions should not be limited to these terms. These terms are only used to distinguish the descriptions. For example, first may also be referred to as second without departing from the scope of the embodiments of this application, and similarly, second may also be referred to as first.

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0054] When performing 3D scanning of large and complex structures, it is necessary to place the laser 3D scanner at different locations and scan from different perspectives. The point clouds obtained from each station are then stitched together to form the overall point cloud of the measured structure. Point cloud stitching generally employs the following methods: 1) Direct fitting and stitching based on the similarity of point clouds in overlapping areas. This method has a large stitching error for point clouds of objects with indistinct geometric features, and for large-scale 3D point clouds, the error accumulates and amplifies with the increase in scanning stations. 2) Based on the precision control field method. This method involves arranging several marker points in the space where the object is located and establishing a globally unified coordinate system using large-scale measuring equipment such as a laser tracker. This is called the global coordinate system. The coordinate system composed of control points determined by the scanning system at each perspective is called the local coordinate system. Based on the Euclidean geometric invariance of the control points, a transformation relationship is established between the local and global coordinate systems. Finally, the measurement data from each perspective are unified to the reference of the global coordinate system, thus completing the global stitching of the 3D data. When measuring global marker points, the accuracy varies greatly depending on the distance between the marker points and the measuring equipment. The accuracy decreases with increasing distance, resulting in inaccurate local coordinate systems at distant locations.

[0055] Based on this, this application proposes a large-size structure laser 3D scanning method based on multi-station fusion, including:

[0056] Construct multiple standard instruments, and select no fewer than four marker points on each standard instrument, denoted as N1-Ni. The marker points of the Nth standard instrument are located in the standard instrument coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4;

[0057] The large structure to be measured is divided into multiple test areas, and multiple standard instruments are respectively set in the multiple test areas. The coordinates of the multiple standard instruments in the global coordinate system X are obtained by scanning equipment. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi );

[0058] Using the aforementioned marker points in the standard coordinate system X A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );

[0059] At different stations, the large-sized structure under test and multiple standard instruments are scanned simultaneously. The results are recorded in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi );

[0060] Based on the marker point on the Nth standard in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ;

[0061] In the global coordinate system X C Y C Z CBelow, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product.

[0062] The three-dimensional laser scanning measurement method proposed in this application uses several calibrated standards as coordinate transformation tools. The relationships between the marker points on the standards are precisely calibrated in advance. During multi-station scanning measurements, the standards are distributed in the measured space. The coordinates of the marker points on each standard in a unified coordinate system are measured using a total station or other measuring equipment. Then, the coordinates in the unified coordinate system are optimized and calibrated using calibration data. During scanning at each station, both the marker points on the standards and the measured product are scanned simultaneously. The data in the calibrated global coordinate system is used to fit and stitch together the scanned point clouds. This ensures both the continuity between point clouds at different stations and the accuracy of local scanned point cloud transformation.

[0063] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0064] like Figure 1 As shown in the specific embodiments of this application, this application provides a large-size structure laser three-dimensional scanning method based on multi-station fusion, including the following steps:

[0065] Step S102: Construct multiple standards, and select no less than 4 marker points on each standard, denoted as N1-Ni. The marker points of the Nth standard are located in the standard coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4;

[0066] Step S104: Divide the large-size structure to be measured into multiple test areas, and set multiple standards in the multiple test areas respectively. Use a scanning device to obtain the coordinates of the multiple standards in the global coordinate system X. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi );

[0067] Step S106: Using each of the aforementioned marker points in the standard coordinate system X A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );

[0068] Step S108: At different stations, scan the large-sized structure under test and multiple standard instruments simultaneously, in the scanner coordinate system X B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi );

[0069] Step S110: Based on the marker point on the Nth standard, in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ;

[0070] Step S112: In the global coordinate system X C YC Z C Below, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product.

[0071] In some embodiments, step S102, constructing multiple standards includes: constructing standard sizes based on the longest size of the large-size structure being measured, such that the longest size of the standard is 1 / 3 to 1 / 4 of the longest size of the large-size structure being measured.

[0072] For products with large-sized structures being tested, some shapes and structures are not standardized. The standard can be constructed based on its longest dimension, which refers to the maximum straight-line distance between any two points on the surface of the large-sized structure. Using this as a reference, the longest dimension of the standard is 1 / 3 to 1 / 4 of the longest dimension of the large-sized structure being tested. To simplify the setting of marker points and reduce computation, the standard is usually a standardized structure, such as a cuboid or cube. In this embodiment, it is a flat structure with a square top and / or bottom surface. At least one face of the standard is a square, and there are four marker points located at the four corners of the square.

[0073] In some embodiments, all the marker points on each of the standard are evenly distributed and not all on the same straight line, because only three points that are not on the same straight line can define a plane, and the six-degree-of-freedom attitude of the standard cannot be calculated when four marker points are on the same straight line.

[0074] In this embodiment, the marker points n1-n4 on the standard instrument N are in the standard instrument coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 ), (X AN2 ,Y AN2 Z AN2 ), (X AN3 ,Y AN3 Z AN3 ), (X AN4 ,Y AN4 Z AN4 The coordinates of each marker point can be precisely calibrated by a metrology institution or using a precision coordinate measuring machine.

[0075] Among them, the standard coordinate system X A Y A Z AAn XYZ Cartesian coordinate system can be constructed with the geometric center of each standard as the origin, or with the vertex of each standard as the origin. There is no limitation on this, and it is used to calibrate the coordinate values ​​of the marker points on each standard.

[0076] In step S104, when scanning the product under test using a scanner, the product under test is divided into several test areas according to the scanner's optimal measurement range and field of view. Each standard is pre-fixed and placed in front of a corresponding test area of ​​the product under test, and a large-size measuring device (such as a laser tracker) is used to measure the marker points on all the standards in the global coordinate system X. C Y C Z C The coordinates below, such as the marker points n1-n4 on the standard instrument N in the global coordinate system X C Y C Z C The coordinates below are: (X) CN1 ,Y CN1 Z CN1 ), (X CN2 ,Y CN2 Z CN2 ), (X CN3 ,Y CN3 Z CN3 ), (X CN4 ,Y CN4 Z CN4 ).

[0077] Wherein, the global coordinate system X C Y C Z C An XYZ Cartesian coordinate system can be constructed based on the measurement environment of the large-sized structural product being measured. All devices in the measurement environment are located in the global coordinate system X. C Y C Z C In this context, coordinate values ​​of all equipment used to calibrate the measurement environment are used.

[0078] In some embodiments, step S106: the step of positioning each of the marker points in the standard coordinate system X A Y A Z A The coordinates below are used as the reference values, and their values ​​are used in relation to the global coordinate system X. C Y C Z C By fitting the lower coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(XACNi ,Y ACNi Z ACNi This includes the following sub-steps:

[0079] Step S106-1: Set the global coordinate system X C Y C Z C To the standard coordinate system X A Y A Z A The transformation matrix is ​​R CAN The translation vector is T. CAN Then we obtain the global coordinate system X. C Y C Z C Lower measurement coordinate values ​​(X) CNi ,Y CNi Z CNi In the standard coordinate system X A Y A Z A Transformed coordinates (X′) ACNi ,Y′ ACNi ,Z′ ACNi )for:

[0080]

[0081] Step S106-3: In the standard coordinate system X A Y A Z A Next, construct a distance equation between the transformed coordinates and calibration coordinates of the Nth standard feature point, and construct an objective function based on the distance minimization criterion:

[0082] M is a natural number greater than or equal to 4;

[0083] Step S106-5: Place each of the marker points on each of the aforementioned standards in the standard coordinate system X. A Y A Z A The calibration coordinates below and the global coordinate system X C Y C Z C Substituting the measured coordinate values ​​into formula (2), the transformation matrix R is obtained through minimum value iterative search. CAN Translation vector T CAN ;

[0084] Step S106-7: Based on formula (1), according to the coordinates of each of the marker points in the standard coordinate system X A Y A Z AThe calibration coordinates are used to calculate the coordinates of the marker point on the Nth standard in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ).

[0085] The solution expression satisfies the following relationship:

[0086]

[0087] In step S108, when scanning the product under test using a 3D scanner, the scanner is sequentially positioned at different stations to scan the product. During the scanning at the Nth station, both the product under test and the marker points on the standard N are scanned simultaneously. This is done within the scanner's coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN And the coordinate values ​​of the standard, for example, the marker points n1-n4 on the standard N in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as: (X BN1 ,Y BN1 Z BN1 ), (X BN2 ,Y BN2 Z BN2 ), (X BN3 ,Y BN3 Z BN3 ), (X BN4 ,Y BN4 Z BN4 ), The scanned point cloud is in the X coordinate system of the scanner at station N. B Y B Z B The matrix below is denoted as D. BN .

[0088] Wherein, the scanner coordinate system X B Y B Z B An XYZ rectangular coordinate system is constructed with the geometric center of scanning equipment such as scanners as the origin, and is used to calibrate the coordinate values ​​of the product being measured and the standard in the measurement environment.

[0089] In some embodiments, step S110: the marker point on the Nth standard is located in the global coordinate system X. C Y C ZC Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN This includes the following sub-steps:

[0090] Step S110-1: Set the scanner coordinate system X B Y B Z B To the global coordinate system X C Y C Z C The transformation matrix is ​​R BCN Translation vector T BCN Then the scanner coordinate system X is obtained. B Y B Z B Lower coordinate value (X) BNi ,Y BNi Z BNi In the global coordinate system X C Y C Z C Lower coordinate value (X) CNi ,Y CNi Z CNi )for:

[0091]

[0092] Step S110-3: Place the marker point on the standard instrument in the global coordinate system X C Y C Z C Corrected coordinates (X) ACNi ,Y ACNi Z ACNi ), and the marker point in the scanner coordinate system X B Y B Z B The coordinates below (X) BNi ,Y BNi Z BNi Substituting into formula (3), the transformation matrix R can be calculated. BCN Translation vector T BCN ;

[0093] Step S110-5: Based on the transformation matrix R BCNTranslation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN .

[0094] In some embodiments, step S110-5: the transformation matrix R BCN Translation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN ,include:

[0095] According to the transformation matrix R BCN Translation vector T BCN The scanned point cloud matrix D is calculated using the following formula (4). BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN

[0096] D CN =R BCN D BN +T BCN (4).

[0097] The point cloud stitching method proposed in this application arranges multiple standard markers with common marker points in the space where the product under test is located. Firstly, the coordinates of the marker points on the standard markers in the standard marker coordinate system are pre-calibrated. Secondly, large-scale measuring equipment (such as laser trackers, total stations, and lidar) is used to measure the coordinates of all common points on the standard markers in a unified coordinate system. Since the measurement error of large-scale measuring equipment increases with distance, it can lead to large measurement errors for distant target points, affecting the scanning stitching. Therefore, the positions in the global coordinate system are first calibrated based on the relationship between the marker points on the standard markers themselves, obtaining calibrated coordinates in the unified coordinate system. When scanning the product under test using a laser 3D scanning device at different stations, the common marker points on the standard markers are scanned simultaneously. The scanned point cloud is transferred to the unified coordinate system using the coordinates of the common points on the calibrated standard markers. Based on this method, the continuity between point clouds at different stations is ensured, while also maintaining the accuracy of local scanned point cloud transformation.

[0098] like Figure 3 As shown, this application also provides a large-size structure laser 3D scanning device based on multi-station fusion, comprising:

[0099] Construction unit 302 is used to construct multiple standards, and select no less than 4 marker points on each standard, denoted as N1-Ni. The marker points of the Nth standard are located in the standard coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4;

[0100] Acquisition unit 304 is used to divide the large-size structure to be measured into multiple test areas, set multiple standards in the multiple test areas respectively, and obtain the coordinates of the multiple standards in the global coordinate system X by scanning device. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi );

[0101] Fitting unit 306 is used to fit each of the said marker points in the standard coordinate system X. A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinates below are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );

[0102] Scanning unit 308 is used to simultaneously scan the large-sized structure under test and multiple standards from different stations, in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below.BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi );

[0103] Transformation unit 310 is used to transform the marker point on the Nth standard in the global coordinate system X. C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ;

[0104] fusion unit 312 is used in the global coordinate system X C Y C Z C Below, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product.

[0105] like Figure 4 As shown, this embodiment provides an electronic device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform the method steps described in the above embodiment.

[0106] This application provides a non-volatile computer storage medium storing computer-executable instructions that can perform the steps described in the above embodiments.

[0107] The following is for reference. Figure 4The diagram illustrates a structural schematic of an electronic device suitable for implementing the embodiments of this application. The terminal devices in the embodiments of this application may include, but are not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 4 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0108] like Figure 4 As shown, the electronic device may include a processing unit (e.g., a central processing unit, a graphics processing unit, etc.) 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 device 408 into a random access memory (RAM) 403. The RAM 403 also stores various programs and data required for the operation of the electronic device. The processing unit 401, ROM 402, and RAM 403 are interconnected via a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0109] Typically, the following devices can be connected to I / O interface 405: input devices 406 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 407 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 408 including, for example, magnetic tapes, hard disks, etc.; and communication devices 409. Communication device 409 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 4 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown. More or fewer devices may be implemented or have alternatively.

[0110] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 409, or installed from a storage device 408, or installed from a ROM 402. When the computer program is executed by the processing device 401, it performs the functions defined in the methods of the embodiments of this application.

[0111] It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium, a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0112] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device.

[0113] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0114] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0115] The units described in the embodiments of this application can be implemented in software or hardware. The names of the units are not, in some cases, limiting the scope of the unit itself.

Claims

1. A method for laser three-dimensional scanning of large-size structures based on multi-station fusion, characterized in that, include: Construct multiple standard instruments, and select no fewer than four marker points on each standard instrument, denoted as N1-Ni. The marker points of the Nth standard instrument are located in the standard instrument coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4; The large structure to be measured is divided into multiple test areas, and multiple standard instruments are respectively set in the multiple test areas. The coordinates of the multiple standard instruments in the global coordinate system X are obtained by scanning equipment. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi ); Using the aforementioned marker points in the standard coordinate system X A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ) At different stations, the large-sized structure under test and multiple standard instruments are scanned simultaneously. The results are recorded in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi ); Based on the marker point on the Nth standard in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ; In the global coordinate system X C Y C Z C Below, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product; The marker points are located in the standard coordinate system X. A Y A Z A The coordinates below are used as the reference values, and their values ​​are used in relation to the global coordinate system X. C Y C Z C By fitting the lower coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ),include: Let the global coordinate system X C Y C Z C To the standard coordinate system X A Y A Z A The transformation matrix is ​​R CAN The translation vector is T. CAN Then we obtain the global coordinate system X. C Y C Z C Lower measurement coordinate values ​​(X) CNi ,Y CNi Z CNi In the standard coordinate system X A Y A Z A Transformed coordinates (X) ACNi ,Y ACNi Z ACNi )for: (1) In the standard coordinate system X A Y A Z A Next, construct a distance equation between the transformed coordinates and calibration coordinates of the Nth standard feature point, and construct an objective function based on the distance minimization criterion: (2), M is a natural number greater than or equal to 4; Place each of the marker points on each of the aforementioned standards in the standard coordinate system X. A Y A Z A The calibration coordinates below and the global coordinate system X C Y C Z C Substituting the measured coordinates into formula (2), the transformation matrix R is obtained through minimum value iterative search. CAN Translation vector T CAN ; Based on formula (1), and according to the coordinates of each of the aforementioned marker points in the standard coordinate system X... A Y A Z A The calibration coordinates are used to calculate the position of the marker point on the Nth standard in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ).

2. The method according to claim 1, characterized in that, The marker point based on the Nth standard is located in the global coordinate system X. C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ,include: Let the scanner coordinate system be X. B Y B Z B To the global coordinate system X C Y C Z C The transformation matrix is ​​R BCN Translation vector T BCN Then the scanner coordinate system X is obtained. B Y B Z B Lower coordinate value (X) BNi ,Y BNi Z BNi In the global coordinate system X C Y C Z C Lower coordinate value (X) CNi ,Y CNi Z CNi )for: (3) Place the marker point on the standard in the global coordinate system X. C Y C Z C Corrected coordinates (X) ACNi ,Y ACNi Z ACNi ), and the marker point in the scanner coordinate system X B Y B Z B The coordinates below (X) BNi ,Y BNi Z BNi Substituting into formula (3), the transformation matrix R can be calculated. BCN Translation vector T BCN ; According to the transformation matrix R BCN Translation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN .

3. The method according to claim 2, characterized in that, The transformation matrix R BCN Translation vector T BCN Calculate the scanned point cloud matrix D BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN ,include: According to the transformation matrix R BCN Translation vector T BCN The scanned point cloud matrix D is calculated using the following formula (4). BN In the global coordinate system X C Y C Z C The point cloud matrix D below CN （4）。 4. The method according to claim 1, characterized in that, The construction of multiple standards includes: The standard size is constructed based on the longest dimension of the large-size structure being tested, such that the longest dimension of the standard is 1 / 3 to 1 / 4 of the longest dimension of the large-size structure being tested.

5. The method according to claim 1, characterized in that, Not all of the marker points on each of the aforementioned standards are on the same straight line.

6. The method according to claim 1, characterized in that, At least one face of the standard is a square, and there are four marker points located at the four corners of the square.

7. A large-size structure laser three-dimensional scanning device based on multi-station fusion, characterized in that, include: A construction unit is used to construct multiple standards. On each standard, at least four marker points are selected, denoted as N1-Ni. The marker points of the Nth standard are located in the standard coordinate system X. A Y A Z A The calibration coordinates below are denoted as (X). AN1 ,Y AN1 Z AN1 )-(X ANi ,Y ANi Z ANi ), where i is a natural number greater than or equal to 4; The acquisition unit is used to divide the large-sized structure to be measured into multiple measurement regions, set multiple standards in the multiple measurement regions respectively, and obtain the coordinates of the multiple standards in the global coordinate system X by a scanning device. C Y C Z C The coordinates below, the marker points of each of the Nth standard instruments in the global coordinate system X C Y C Z C The measured coordinate values ​​are denoted as (X). CN1 ,Y CN1 Z CN1 )-(X CNi ,Y CNi Z CNi ); Fitting unit, used to fit each of the said marker points in the standard coordinate system X A Y A Z A The calibration coordinates below are the reference values, and their global coordinate system X is used as the reference value. C Y C Z C By fitting the measured coordinate values, the marker point on the Nth standard is obtained in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi );include: Let the global coordinate system X C Y C Z C To the standard coordinate system X A Y A Z A The transformation matrix is ​​R CAN The translation vector is T. CAN Then we obtain the global coordinate system X. C Y C Z C Lower measurement coordinate values ​​(X) CNi ,Y CNi Z CNi In the standard coordinate system X A Y A Z A Transformed coordinates (X) ACNi ,Y ACNi Z ACNi )for: (1) In the standard coordinate system X A Y A Z A Next, construct a distance equation between the transformed coordinates and calibration coordinates of the Nth standard feature point, and construct an objective function based on the distance minimization criterion: (2), M is a natural number greater than or equal to 4; Place each of the marker points on each of the aforementioned standards in the standard coordinate system X. A Y A Z A The calibration coordinates below and the global coordinate system X C Y C Z C Substituting the measured coordinates into formula (2), the transformation matrix R is obtained through minimum value iterative search. CAN Translation vector T CAN ; Based on formula (1), and according to the coordinates of each of the aforementioned marker points in the standard coordinate system X... A Y A Z A The calibration coordinates are used to calculate the position of the marker point on the Nth standard in the global coordinate system X. C Y C Z C The corrected coordinate values ​​are denoted as (X). ACN1 ,Y ACN1 Z ACN1 )-(X ACNi ,Y ACNi Z ACNi ); The scanning unit is used to simultaneously scan the large-sized structure under test and multiple standards from different stations, in the scanner coordinate system X. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN and the coordinate values ​​of the standard, wherein the marker points of the Nth standard are in the scanner coordinate system X. B Y B Z B The coordinates below are denoted as (X). BN1 ,Y BN1 Z BN1 )-(X BNi ,Y BNi Z BNi ); Transformation unit, used to transform the marker point on the Nth standard in the global coordinate system X C Y C Z C Corrected coordinate values ​​under and in the scanner coordinate system X B Y B Z B The coordinate values ​​below will be used to define the X coordinate system of the scanner. B Y B Z B The point cloud matrix D of the large-size structure under test is obtained below. BN Transform to global coordinate system X C Y C Z C The point cloud matrix D below CN ; Fusion unit, used in global coordinate system X C Y C Z C Below, the point cloud matrix D obtained from each station is transformed. CN They are combined to form the final point cloud matrix of the tested product.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 6.

9. An electronic device, characterized in that, include: One or more processors; A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the method as described in any one of claims 1 to 6.

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