Splicing method and system of large-scale structural member wireframe model based on three-dimensional point cloud

Abstract

The invention discloses a splicing method and system of a large-scale structural member wireframe model based on a three-dimensional point cloud, and the method comprises the steps: dividing a large-scale structural member into a plurality of adjacent scanning regions, and scanning each adjacent scanning region through scanning equipment to obtain a point cloud; based on the shape and structure characteristics of the structural member, the obtained point cloud is analyzed through a point cloud processing technology, and a plurality of groups of wireframe models of adjacent scanning areas are obtained; analyzing and judging the obtained multiple groups of wireframe models to obtain wireframe models with wireframe model splicing conditions; and for the wireframe models with wireframe model splicing conditions, correctly combining multiple groups of wireframe models into a complete wireframe model based on the shape and structure characteristics of the large structural member. According to the invention, local scanning and feature analysis are carried out on the large-scale structural member, and the complete wireframe model is finally combined, so that subsequent three-dimensional rapid model reconstruction is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of machine vision processing technology, and in particular to a method and system for splicing a wireframe model of a large structural part based on a three-dimensional point cloud. Background Art

[0002] Welding plays a crucial role in the production and processing of large steel gates. It is a critical step in firmly connecting the various components and is directly related to the quality and performance of the gates. However, in actual production, most companies still choose to use manual welding. This method requires extremely high professional skills from welders, requiring extensive experience and sophisticated techniques to ensure weld quality. However, over-reliance on these skilled individuals also brings a series of problems. First, the training of professional welders is costly and time-consuming, and such talent is relatively scarce in the market. This forces companies to pay high salaries to attract and retain them, significantly increasing production costs. Second, manual welding speed is limited by many factors, such as worker proficiency and fatigue, making efficient production difficult and resulting in relatively low production efficiency. Furthermore, the welding process produces toxic gases such as carbon monoxide and nitrogen oxides, as well as intense heat radiation. Without proper protection against these harmful substances, workers can suffer serious health hazards, such as respiratory diseases and vision loss.

[0003] Many existing small and medium-sized enterprises produce steel gates, which are large, non-standard metal structures. These products are diverse and cover a wide range of application scenarios and needs, resulting in a wide range of shapes, sizes, and specifications. Scanning, analyzing, and remodeling these large, non-standard structures in a single operation presents numerous challenges. Due to the large size and complex shapes of these structures, scanning equipment requires a wide field of view and high resolution to fully and accurately capture every detail. However, current scanning equipment on the market struggles to meet the requirements for a complete, one-time scan in key parameters such as field of view and resolution. Achieving this performance often requires significant investment in high-end equipment and technological research and development, which undoubtedly increases the cost burden for enterprises. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology. To achieve the above purpose, a method and system for splicing wireframe models of large structural parts based on three-dimensional point clouds are adopted to solve the problems raised in the above background technology.

[0005] A method for splicing a wireframe model of a large structural component based on a three-dimensional point cloud comprises the following steps:

[0006] Step S1: Divide the large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area using a scanning device to obtain a point cloud;

[0007] Step S2: Based on the shape and structural characteristics of the structural component, the acquired point cloud is analyzed by point cloud processing technology to obtain multiple groups of wireframe models of adjacent scanning areas;

[0008] Step S3: Analyze and judge the obtained multiple sets of wireframe models to obtain wireframe models that meet the wireframe model splicing conditions;

[0009] Step S4: for wireframe models that meet the wireframe model splicing conditions, based on the shape and structural characteristics of large structural parts, correctly merge multiple groups of wireframe models into a complete wireframe model.

[0010] As a further solution of the present invention: the specific steps in step S1 include:

[0011] Step S11: selecting the size of the adjacent scanning area based on the field of view of the 3D camera and the three-dimensional size of the structural component, and dividing the structural component into regions;

[0012] Step S12: calibrate the 3D camera to determine the camera coordinate system for subsequent conversion of 3D point cloud processing result data;

[0013] Step S13: Move the 3D camera to above the adjacent scanning area by moving the truss;

[0014] Step S14: Control the 3D camera through the 3D camera API to shoot the adjacent scanning area to obtain the 3D point cloud information of the area;

[0015] Step S15: Save the acquired three-dimensional point cloud data for subsequent point cloud processing.

[0016] As a further solution of the present invention: the specific steps in step S2 include:

[0017] Step S21, obtaining a three-dimensional point cloud obtained by scanning;

[0018] Step S22: performing coordinate conversion on the 3D point cloud, converting the 3D point cloud from the camera coordinate system to the world coordinate system, to facilitate subsequent point cloud processing;

[0019] Step S23: downsampling, filtering, feature extraction, binarization, and rectangular segmentation are performed on the 3D point cloud, and based on the shape and structural characteristics of the structural parts, a wireframe model of the adjacent scanning area is obtained and stored in the wireframe model set R i .

[0020] As a further solution of the present invention: the specific steps in step S3 include:

[0021] Step S31: Get the wireframe model set R according to step S2. i Read rectangle r in {r1,r2,r3,...} k ∈R i ;

[0022] Step S32, traverse and R i The wireframe model set R of adjacent adjacent scanning areas j {r1,r2,r3,...},i≠j, find the rectangle r k ∈R i The joined rectangles r h ∈R j If the set has been traversed, step S31 is executed;

[0023] Step S33: If the rectangle r k ∈R i With rectangle r h ∈R j If the difference between the attitude angles |α1-α2| is less than the threshold θ1, the two rectangles are parallel and step S34 is executed; otherwise, step S32 is executed;

[0024] Step S34: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β is less than the threshold θ2, the two rectangles are distributed on a straight line parallel to the long side of the rectangle, which meets the preliminary conditions for horizontal splicing, and step S37 is executed; otherwise, step S35 is executed;

[0025] Step S35: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β is less than 90° and greater than the threshold θ3, the two rectangles are distributed on a straight line parallel to the short sides of the rectangles, and the preliminary conditions for longitudinal splicing are met, and step S38 is executed;

[0026] Step S36: If the rectangle r k ∈R i With rectangle r h ∈R j If the conditions of step S34 and step S35 are not met, the two rectangles do not meet the splicing conditions, and step S32 is executed;

[0027] Step S37: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance dkh If the value is less than the sum of the half-widths of the two rectangles multiplied by a certain threshold coefficient λ, then the two rectangles partially overlap or are close to each other and meet the conditions for horizontal splicing;

[0028] Step S38: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance d kh If it is less than the sum of the half-heights of the two rectangles multiplied by a certain threshold coefficient λ, then the two rectangles are partially overlapping or close to each other and meet the conditions for vertical splicing;

[0029] Step S39: If the rectangle r k ∈R i With rectangle r h ∈R j If the conditions of step S38 and step S39 are not met, the two rectangles do not meet the splicing conditions, and step S32 is executed.

[0030] As a further solution of the present invention: the specific steps in step S4 include:

[0031] Step S41: For those that meet the conditions for wireframe model splicing, splicing is performed based on the shape and structural characteristics of the large metal structural parts, including horizontal splicing and vertical splicing;

[0032] Step S42: Connect rectangle r k ∈R i With rectangle r h ∈R j The center point of the center point segment is taken as the midpoint of the new rectangle r l The center point of

[0033] Step S43: Take rectangle r k ∈R i With rectangle r h ∈R j The average value of the posture angle (α1+α2) / 2 is used as the new rectangle r l The attitude angle α l ;

[0034] Step S44: Rectangle r k ∈R i The half-width w k / 2, rectangle r h ∈R j The half-width w k / 2 and the distance between the center point d kh At the new attitude angle α l The projection distance d on the straight line kh The sum of the three cosβ is taken as the new rectangle r lWidth w l ;

[0035] Step S45: use rectangle r k ∈R i Half height h k / 2, rectangle r h ∈R j Half height h k / 2 and the distance d from the center point kh At the new attitude angle α l The projection distance d on the perpendicular line of the straight line kh The sum of sinβ is taken as the new rectangle r l High h l ;

[0036] Step S46: Transmitting the information of the complete wireframe model after splicing in the world coordinate system to the 3D modeling software to generate a corresponding 3D model;

[0037] Step S47: Replace the adjacent scanning area with a new one, and continue to re-execute step S11 until all adjacent scanning areas are processed.

[0038] Another technical solution is a system using any of the above-mentioned methods for splicing wireframe models of large structural parts based on three-dimensional point clouds, comprising:

[0039] A point cloud acquisition module, which is used to divide a large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area using a scanning device to obtain a point cloud;

[0040] A point cloud processing module is used to analyze the acquired point cloud based on the shape and structural characteristics of the structural component through point cloud processing technology to obtain wireframe models of multiple groups of adjacent scanning areas;

[0041] A splicing condition analysis module, wherein the splicing condition analysis module is used to analyze and judge the multiple sets of wireframe models to obtain a wireframe model that meets the wireframe model splicing conditions;

[0042] The wireframe splicing module is used to correctly merge multiple groups of wireframe models that meet the wireframe model splicing conditions into a complete wireframe model based on the shape and structural characteristics of large structural parts.

[0043] Compared with the prior art, the present invention has the following technical effects:

[0044] Using the above technical solution, by analyzing the features of partial wireframe models of large structural components, multiple partial wireframe models can be correctly stitched together into a complete wireframe model. This method can identify and create wireframe models of large structural components using a 3D camera with a smaller field of view, eliminating the need for costly large-field-of-view 3D cameras. This method can accommodate large structural components of varying sizes with specific structural shapes. The overall method is widely applicable, simple to implement, and highly automated. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0046] Figure 1 A flowchart of the method disclosed in the present application;

[0047] Figure 2 This is a point cloud acquisition flowchart of the embodiment disclosed in this application;

[0048] Figure 3 This is a flowchart of point cloud processing according to an embodiment disclosed in this application;

[0049] Figure 4 A schematic diagram of a rectangular posture angle in a wireframe model of an embodiment disclosed in this application;

[0050] Figure 5 A schematic diagram of the relative orientation angles of a pair of rectangles in a wireframe model of an embodiment disclosed in this application;

[0051] Figure 6 This is a flowchart of wireframe splicing condition analysis for the embodiment disclosed in this application;

[0052] Figure 7 This is a point cloud acquisition effect diagram of the adjacent scanning area of the embodiment disclosed in this application;

[0053] Figure 8 This is a rendering of the point cloud processing and wireframe model of the adjacent scanning area of the embodiment disclosed in this application;

[0054] Figure 9 A wireframe splicing flowchart of an embodiment disclosed in this application;

[0055] Figure 10 A schematic diagram of a pair of rectangles in a wireframe model of an embodiment disclosed in this application

[0056] Figure 11 This is the wireframe model splicing effect of the embodiment disclosed in this application. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] Please refer to Figure 1 In an embodiment of the present invention, a method and system for splicing a wireframe model of a large structural part based on a three-dimensional point cloud includes the following steps:

[0059] Step S1: Divide the large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area with a scanning device to obtain a point cloud. The specific steps include:

[0060] like Figure 2 As shown, the figure is a point cloud acquisition flow chart;

[0061] Step S11: selecting the size of the adjacent scanning area based on the field of view of the 3D camera and the three-dimensional size of the structural component, and dividing the structural component into regions;

[0062] Step S12: calibrate the 3D camera to determine the camera coordinate system for subsequent conversion of 3D point cloud processing result data;

[0063] Step S13: Move the 3D camera to above the adjacent scanning area by moving the truss;

[0064] Step S14: Control the 3D camera through the 3D camera API to shoot the adjacent scanning area to obtain the 3D point cloud information of the area;

[0065] Step S15: Save the acquired three-dimensional point cloud data for subsequent point cloud processing.

[0066] In this embodiment, since the size of large metal structures is often much larger than the field of view of a 3D camera, it is necessary to divide the structure into regions, and use a movable truss to carry the 3D camera to acquire point clouds for each adjacent scanning area;

[0067] Step S2: Based on the shape and structural characteristics of the structural component, the acquired point cloud is analyzed using point cloud processing technology to obtain multiple sets of wireframe models of adjacent scanning areas. The specific steps include:

[0068] like Figure 3 As shown, the figure is a point cloud processing flow chart;

[0069] Step S21, obtaining a three-dimensional point cloud obtained by scanning;

[0070] Step S22: performing coordinate conversion on the 3D point cloud, converting the 3D point cloud from the camera coordinate system to the world coordinate system, to facilitate subsequent point cloud processing;

[0071] Step S23: perform downsampling, filtering, feature extraction, binarization, and rectangle segmentation on the 3D point cloud, and obtain the wireframe model of the adjacent scanning area based on the shape and structure characteristics of the structural parts and store it in the wireframe model set R i .

[0072] In this embodiment, the wireframe model is a simplified model derived from the shape characteristics of the structural component and is defined as follows:

[0073] The wireframe model consists of multiple rectangles, represented by R i {r1,r2,r3,...};

[0074] The intersection of the two diagonals of a rectangle is the center point of the rectangle;

[0075] The long side of the rectangle is width w, and the short side is height h;

[0076] The angle between the straight line where the long side of the rectangle is located and the positive direction of the X-axis is defined as the posture angle α of the rectangle. The value range of the posture angle is α∈[-90,90]. Figure 4 As shown, the figure is a schematic diagram of a rectangular attitude angle;

[0077] The line passing through the center point of a rectangle and the center point of another rectangle is defined as the line connecting the center points of a pair of rectangles. The angles between the line connecting the center points and the lines on which the long sides of the two rectangles lie are β1 and β2 respectively. β = (β1 + β2) / 2 is defined as the relative orientation angle of the pair of rectangles. The range of β1, β2 and β is β1, β2, β∈[0,90].

[0078] like Figure 5 As shown, the figure is a schematic diagram of the relative orientation angles of a pair of rectangles in a wireframe model;

[0079] The length of a line segment starting from the center point of a rectangle and ending at the center point of another rectangle is defined as the distance d between the center points of a pair of rectangles. ij ;

[0080] The splicing between rectangles where the short sides touch each other is defined as horizontal splicing;

[0081] The splicing between rectangles where the long sides touch each other is defined as longitudinal splicing;

[0082] Step S3: Analyze and judge the obtained multiple wireframe models to obtain wireframe models that meet the wireframe model splicing conditions. The specific steps include:

[0083] like Figure 6 As shown, the figure is a flow chart of wireframe splicing condition analysis;

[0084] Step S31: From the wireframe model set R i Read a rectangle r from {r1,r2,r3,...} k ∈R i ;

[0085] Step S32, traverse and R i The wireframe model set R of adjacent adjacent scanning areas j {r1,r2,r3,...},i≠j, find the rectangle r k ∈R i The joined rectangles r h ∈R j If the set has been traversed, step S31 is executed;

[0086] like Figure 7 As shown, the figure shows the point cloud acquisition effect diagram of the adjacent scanning area;

[0087] like Figure 8 As shown, the figure shows the point cloud processing and wireframe model effect diagram of the adjacent scanning area;

[0088] Step S33: If the rectangle r k ∈R i With rectangle r h ∈R j If the difference between the posture angles |α1-α2| is less than the threshold θ1, that is, 0≤|α1-α2|≤θ1, it is determined that the two rectangles are approximately parallel, and step S34 is executed; otherwise, step S32 is executed;

[0089] Step S34: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β of the rectangles is less than the threshold value θ2, that is, 0≤β≤θ2, it is determined that the two rectangles are approximately distributed on a straight line parallel to the long side of the rectangle, and the preliminary conditions for horizontal splicing are met, and step S37 is executed; otherwise, step S35 is executed;

[0090] Step S35: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β is less than 90° and greater than the threshold θ3, that is, θ3≤β≤90, it is determined that the two rectangles are distributed on a straight line parallel to the short sides of the rectangles, and the preliminary conditions for longitudinal splicing are met, and step S38 is executed;

[0091] Step S36: If the rectangle r k ∈R i With rectangle r h ∈R jIf the conditions of step S34 and step S35 are not met, it is determined that the two rectangles do not meet the splicing conditions, and step S32 is executed;

[0092] Step S37: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance d kh Less than the sum of the half widths of the two rectangles multiplied by a certain threshold coefficient λ, that is, d kh <λ(w k +w h ) / 2, then the two rectangles are considered to be partially overlapping or close to each other, and meet the conditions for horizontal splicing;

[0093] Step S38: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance d kh Less than the sum of the half heights of the two rectangles multiplied by a certain threshold coefficient λ, that is, d kh <λ(h k +h h ) / 2, then the two rectangles are considered to be partially overlapping or close to each other, and meet the conditions for longitudinal splicing;

[0094] Step S39: If the rectangle r k ∈R i With rectangle r h ∈R j If the conditions of step S38 and step S39 are not met, it is determined that the two rectangles do not meet the splicing conditions, and step S32 is executed.

[0095] Step S4: For wireframe models that meet the conditions for wireframe model splicing, based on the shape and structural characteristics of large structural parts, correctly merge multiple wireframe models into a complete wireframe model. The specific steps include:

[0096] like Figure 9 As shown, the figure is a wireframe splicing flow chart;

[0097] Step S41: For those that meet the conditions for wireframe model splicing, splicing is performed based on the shape and structural characteristics of the large metal structural parts, including horizontal splicing and vertical splicing;

[0098] Step S42: Connect rectangle r k ∈R i With rectangle r h ∈R j The center point of the center point segment is taken as the midpoint of the new rectangle r l The center point of

[0099] Step S43: Take rectangle r k ∈R i With rectangle r h ∈R j The average value of the posture angle (α1+α2) / 2 is used as the new rectangle r l The attitude angle α l ;

[0100] Step S44: Rectangle r k ∈R i The half-width w k / 2, rectangle r h ∈R j The half-width w k / 2 and the distance d from the center point kh At the new attitude angle α l The projection distance d on the straight line kh The sum of the three cosβ is taken as the new rectangle r l Width w l , the calculation formula is:

[0101] w l =w k / 2+w h / 2+d kh cosβ;

[0102] Step S45: use rectangle r k ∈R i Half height h k / 2, rectangle r h ∈R j Half height h k / 2 and the distance d from the center point kh At the new attitude angle α l The projection distance d on the perpendicular line of the straight line kh The sum of sinβ is taken as the new rectangle r l High h l , the calculation formula is:

[0103] h l =h k / 2+h h / 2+d kh sinβ;

[0104] like Figure 10 As shown, the figure is a schematic diagram of the splicing of a pair of rectangles in a wireframe model;

[0105] Step S46: Transmitting the information of the complete wireframe model after splicing in the world coordinate system to the 3D modeling software to generate a corresponding 3D model for subsequent welding;

[0106] Step S47: Replace the adjacent scanning area with a new one, and continue to re-execute step S11 until all adjacent scanning areas are processed.

[0107] like Figure 11 As shown, the figure shows the wireframe model splicing effect;

[0108] Another technical solution is a system using any of the above-mentioned methods for splicing wireframe models of large structural parts based on three-dimensional point clouds, comprising:

[0109] A point cloud acquisition module, which is used to divide a large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area using a scanning device to obtain a point cloud;

[0110] A point cloud processing module is used to analyze the acquired point cloud based on the shape and structural characteristics of the structural component through point cloud processing technology to obtain wireframe models of multiple groups of adjacent scanning areas;

[0111] A splicing condition analysis module, wherein the splicing condition analysis module is used to analyze and judge the multiple sets of wireframe models to obtain a wireframe model that meets the wireframe model splicing conditions;

[0112] The wireframe splicing module is used to correctly merge multiple groups of wireframe models that meet the wireframe model splicing conditions into a complete wireframe model based on the shape and structural characteristics of large structural parts.

[0113] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents, and all should be included within the scope of protection of the present invention.

Claims

1. A method for splicing wireframe models of large structural parts based on three-dimensional point clouds, characterized in that: The following steps are involved: Step S1: Divide the large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area using a scanning device to obtain a point cloud; Step S2: Based on the shape and structural characteristics of the structural component, the acquired point cloud is analyzed by point cloud processing technology to obtain multiple groups of wireframe models of adjacent scanning areas; Step S3: Analyze and judge the obtained multiple sets of wireframe models to obtain wireframe models that meet the wireframe model splicing conditions; Step S4: for wireframe models that meet the wireframe model splicing conditions, based on the shape and structural characteristics of large structural parts, correctly merge multiple groups of wireframe models into a complete wireframe model.

2. The method for splicing a wireframe model of a large structural part based on a three-dimensional point cloud according to claim 1, characterized in that: The specific steps in step S1 include: Step S11: selecting the size of the adjacent scanning area based on the field of view of the 3D camera and the three-dimensional size of the structural component, and dividing the structural component into regions; Step S12: calibrate the 3D camera to determine the camera coordinate system for subsequent conversion of 3D point cloud processing result data; Step S13: Move the 3D camera to above the adjacent scanning area by moving the truss; Step S14: Control the 3D camera through the 3D camera API to shoot the adjacent scanning area to obtain the 3D point cloud information of the area; Step S15: Save the acquired three-dimensional point cloud data for subsequent point cloud processing.

3. The method for splicing a wireframe model of a large structural part based on a three-dimensional point cloud according to claim 1, characterized in that: The specific steps in step S2 include: Step S21, obtaining a three-dimensional point cloud obtained by scanning; Step S22: performing coordinate conversion on the 3D point cloud, converting the 3D point cloud from the camera coordinate system to the world coordinate system, to facilitate subsequent point cloud processing; Step S23: downsampling, filtering, feature extraction, binarization, and rectangular segmentation are performed on the 3D point cloud, and based on the shape and structural characteristics of the structural parts, a wireframe model of the adjacent scanning area is obtained and stored in the wireframe model set R i .

4. The method for splicing a wireframe model of a large structural part based on a three-dimensional point cloud according to claim 1, characterized in that: The specific steps in step S3 include: Step S31: Get the wireframe model set R according to step S2. i Read rectangle r in {r1,r2,r3,...} k ∈R i ; Step S32, traverse and R i The wireframe model set R of adjacent adjacent scanning areas j {r1,r2,r3,...},i≠j, find the rectangle r k ∈R i The joined rectangles r h ∈R j If the set has been traversed, step S31 is executed; Step S33: If the rectangle r k ∈R i With rectangle r h ∈R j If the difference between the attitude angles |α1-α2| is less than the threshold θ1, the two rectangles are parallel and step S34 is executed; otherwise, step S32 is executed; Step S34: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β is less than the threshold θ2, the two rectangles are distributed on a straight line parallel to the long side of the rectangle, which meets the preliminary conditions for horizontal splicing, and step S37 is executed; otherwise, step S35 is executed; Step S35: If the rectangle r k ∈R i With rectangle r h ∈R j If the relative azimuth angle β is less than 90° and greater than the threshold θ3, the two rectangles are distributed on a straight line parallel to the short sides of the rectangles, and the preliminary conditions for longitudinal splicing are met, and step S38 is executed; Step S36: If the rectangle r k ∈R i With rectangle r h ∈R j If the conditions of step S34 and step S35 are not met, the two rectangles do not meet the splicing conditions, and step S32 is executed; Step S37: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance d kh If the value is less than the sum of the half-widths of the two rectangles multiplied by a certain threshold coefficient λ, then the two rectangles partially overlap or are close to each other and meet the conditions for horizontal splicing; Step S38: If the rectangle r k ∈R i With rectangle r h ∈R j The center distance d kh If it is less than the sum of the half-heights of the two rectangles multiplied by a certain threshold coefficient λ, then the two rectangles are partially overlapping or close to each other and meet the conditions for vertical splicing; Step S39: If the rectangle r k ∈R i With rectangle r h ∈R j If the conditions of step S38 and step S39 are not met, the two rectangles do not meet the splicing conditions, and step S32 is executed.

5. The method for splicing a wireframe model of a large structural part based on a three-dimensional point cloud according to claim 1, characterized in that: The specific steps in step S4 include: Step S41: For those that meet the conditions for wireframe model splicing, splicing is performed based on the shape and structural characteristics of the large metal structural parts, including horizontal splicing and vertical splicing; Step S42: Connect rectangle r k ∈R i With rectangle r h ∈R j The center point of the center point segment is taken as the midpoint of the new rectangle r l The center point of Step S43: Take rectangle r k ∈R i With rectangle r h ∈R j The average value of the posture angle (α1+α2) / 2 is used as the new rectangle r l The attitude angle α l ; Step S44: Rectangle r k ∈R i The half-width w k / 2, rectangle r h ∈R j The half-width w k / 2 and the distance between the center point d kh At the new attitude angle α l The projection distance d on the straight line kh The sum of the three cosβ is taken as the new rectangle r l Width w l ; Step S45: use rectangle r k ∈R i Half height h k / 2, rectangle r h ∈R j Half height h k / 2 and the distance between the center point d kh At the new attitude angle α l The projection distance d on the perpendicular line of the straight line kh The sum of sinβ is taken as the new rectangle r l High h l ; Step S46: Transmitting the information of the complete wireframe model after splicing in the world coordinate system to the 3D modeling software to generate a corresponding 3D model; Step S47: Replace the adjacent scanning area with a new one, and continue to re-execute step S11 until all adjacent scanning areas are processed.

6. A system using the method for splicing a large structural part wireframe model based on a three-dimensional point cloud as claimed in any one of claims 1 to 5, characterized in that: include: A point cloud acquisition module, which is used to divide a large structural part into multiple adjacent scanning areas, and then scan each adjacent scanning area using a scanning device to obtain a point cloud; A point cloud processing module is used to analyze the acquired point cloud based on the shape and structural characteristics of the structural component through point cloud processing technology to obtain wireframe models of multiple groups of adjacent scanning areas; A splicing condition analysis module, wherein the splicing condition analysis module is used to analyze and judge the multiple sets of wireframe models to obtain a wireframe model that meets the wireframe model splicing conditions; The wireframe splicing module is used to correctly merge multiple groups of wireframe models that meet the wireframe model splicing conditions into a complete wireframe model based on the shape and structural characteristics of large structural parts.

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