Methods, systems, equipment, and media for extracting structural drawings based on hidden line removal relationships.

Abstract

This invention discloses a structural drawing extraction method based on hidden-line removal relationships, comprising: defining a drawing style containing a "merge to" attribute that controls the merging behavior of adjacent structures; establishing a drawing cube to precisely define the drawing range and sectioning perspective; performing hidden-line removal calculations and sectioning calculations in parallel to generate hidden-line removal calculation results and sectioning calculation results carrying unique identifiers of model objects; grouping the calculation results according to the unique identifiers; merging spatially adjacent results that meet the conditions based on the "merge to" attribute to generate merged drawing results; assigning style attributes to the drawing results to automatically generate compliant 2D drawings. This invention also discloses a structural drawing extraction system, equipment, and medium based on hidden-line removal relationships. This invention solves the problems of inaccurate hidden-line removal processing, low automation of drawing generation, and poor drawing standardization in existing technologies, achieving efficient and high-precision automatic conversion from 3D models to 2D construction drawings.

Description

Technical Field

[0001] This invention belongs to the field of Building Information Modeling (BIM) and Computer-Aided Design (CAD) technology, and particularly relates to a method, system, device and medium for extracting structural drawings based on hidden surface relationships. Background Technology

[0002] In the field of building engineering, Building Information Modeling (BIM) technology has become a core tool for the industry's digital transformation due to its advantages such as visualization, parametric design, coordination, simulation, optimization, and information completeness. It is widely used in civil engineering infrastructure design and other fields.

[0003] However, in actual engineering projects, the final deliverables used to guide construction are still mainly two-dimensional drawings. Therefore, how to automatically and accurately generate high-quality two-dimensional drawings that conform to industry drafting standards from BIM three-dimensional models is a key factor affecting the in-depth application of BIM technology.

[0004] Currently, the mainstream methods for generating 2D drawings from 3D models have several inherent defects, mainly manifested in low automation, insufficient accuracy, and poor standardization, as detailed below:

[0005] 1) Drawing based on sectioning and projection.

[0006] This method generates 2D drawings by sectioning a 3D model and projecting it onto a projection plane. However, the initial projection drawing generated by this method only contains basic geometric lines and cannot automatically handle complex hidden surface relationships (such as the dashed line representation of obscured components). Furthermore, it lacks compliant section filling, line type settings, and dimensioning. For intricate parts such as steel structure nodes and complex curtain walls, extensive manual post-processing and annotation are required, which is not only inefficient but also highly susceptible to human error, making it difficult to guarantee drawing quality.

[0007] 2) Model parameter mapping is combined with 2D drawing software to generate graphs.

[0008] This method generates drawings by establishing a mapping relationship between BIM model parameters and 2D drafting software. The core problem lies in the extremely cumbersome process of establishing the mapping rules, requiring users to be proficient in the system architecture of both BIM and 2D CAD software, resulting in a high technical threshold. Furthermore, in multi-disciplinary collaborative design, differences in data formats between different software platforms can easily lead to information mapping errors or loss. When design changes occur, the association between the 3D model and 2D drawings is difficult to maintain automatically, often requiring manual remapping and verification, significantly increasing the complexity and maintenance costs of collaborative work.

[0009] 3) The 3D model can be directly output as a 2D drawing.

[0010] This method attempts to directly convert 3D views and their annotation parameters into 2D drawings. However, the conversion results often fail to meet strict drafting standards, commonly exhibiting problems such as chaotic dimension layout, redundant or missing annotation information, and inaccurate differentiation of components by line types and widths. The generated drawings have poor readability, particularly inadequate in expressing complex spatial relationships, rendering them unusable for direct construction. Designers still need to perform extensive manual adjustments and optimizations, thus failing to effectively realize the benefits of automation. Summary of the Invention

[0011] To address the deficiencies in the aforementioned background technology, this invention aims to provide a method, system, device, and medium for extracting structural drawings based on hidden boundary removal relationships, thereby overcoming problems such as inaccurate hidden boundary removal processing, difficulty in eliminating virtual boundaries, and insufficient drawing efficiency and standardization when generating two-dimensional drawings from three-dimensional models.

[0012] The core of this invention lies in achieving precise control and intelligent merging of drawing elements by introducing configurable drawing styles and an innovative "merge to" attribute; flexibly defining the drawing range and sectioning perspective by defining a drawing cube structure; performing hidden surface removal and sectioning calculations on model objects located inside the drawing cube, and reorganizing and classifying the calculation results based on the unique identifier of the model objects; and finally automatically rendering and generating two-dimensional drawings that conform to engineering drawing specifications based on style rules.

[0013] This method can automatically achieve intelligent merging of adjacent areas (eliminating virtual boundaries in BIM models), accurate section filling and line type expression, effectively improving the automation, accuracy and standardization of drawing generation, and is particularly suitable for drawing requirements of complex structural models of industrial and civil buildings and various infrastructures.

[0014] Therefore, the first objective of this invention is to provide a method for extracting structural drawings based on hidden line removal relationships, which includes the following steps:

[0015] Define and configure the drawing style for the model object to be drawn. The drawing style includes basic attributes, visible edge attributes, hidden edge attributes, section plane attributes, and "merge to" attribute used to control the merging behavior of adjacent structural regions.

[0016] Based on the spatial range, cutting plane, and drawing direction parameters, a drawing cube is established to define the drawing range;

[0017] Perform hidden surface removal calculation on the model object located inside the output cube to generate a hidden surface removal calculation result, wherein the hidden surface removal calculation result carries a unique identifier of the model object;

[0018] Perform sectioning calculations on the model object located inside the output cube to generate sectioning calculation results, and the sectioning calculation results carry the unique identifier of the model object;

[0019] Grouping the hidden surface removal calculation results and the sectioning calculation results based on the unique identifier of the model object;

[0020] Traverse the result groups, determine whether spatially adjacent result groups meet the merging conditions determined by the "Merge to" attribute in the output style, and perform a merging operation on adjacent result groups that meet the conditions to generate the merged output result;

[0021] Assign the style attributes defined in the drawing style to the output drawing result, and generate the final drawing.

[0022] Preferably, the configuration rules for the "merge into" attribute include:

[0023] When the "Merge to" attribute is set to the name of its own style, the merging function of adjacent structures of the same style is enabled;

[0024] When the “Merge to” attribute is set to the name of another output style, the current style will inherit and use the attributes of the specified target style.

[0025] Preferably, the output cube is created in one of the following three ways:

[0026] The model bounding box method calculates the bounding box of a 3D model and generates cutting planes and drawing directions based on user-specified reference planes.

[0027] The three-point method determines the cutting plane, forward direction, and cutting depth by using three points specified by the user in the two-dimensional view plane.

[0028] The surface shape element definition method directly defines the shape of the cutting surface through a user-defined plane or closed polyline, and uses the normal vector of the surface as the drawing direction.

[0029] Preferably, the step of performing hidden surface removal calculation on the model objects located inside the output cube and generating the hidden surface removal calculation result includes the following steps:

[0030] Perform hidden surface removal calculations on the front view area, including performing back face removal algorithm to remove unseen faces and filter out possible visible faces, and then performing projection distance method to determine the visibility of faces that have not been determined by the back face removal algorithm.

[0031] The back-view region is subjected to hidden surface removal calculation, which includes performing a back-face hidden surface removal algorithm to remove unseen faces and filter out possible visible faces. Then, the projection distance method is used to determine the visibility of faces that have not been determined by the back-face hidden surface removal algorithm.

[0032] Preferably, performing sectioning calculations on the model objects located within the output cube includes at least one of the following methods:

[0033] Perform sectioning calculations on the solid model and generate a closed polygonal cross section formed by the intersection of the solid model object and the sectioning plane as the sectioning calculation result;

[0034] Perform sectioning calculations on a 2D graphic and generate line segments resulting from the intersection of the 2D graphic model object and the sectioning plane as the sectioning calculation results;

[0035] Perform sectioning calculations on the line elements and generate the intersection points of the line element model objects and the sectioning planes as the sectioning calculation results.

[0036] The second objective of this invention is to provide a structural drawing extraction system based on hidden line removal relationships, the system comprising:

[0037] The drawing style configuration module is used to define and configure the drawing style for the model object to be drawn. The drawing style includes basic attributes, visible edge attributes, hidden edge attributes, section plane attributes, and "merge to" attribute used to control the merging behavior of adjacent structural regions. It provides users with a parameterized interface to generate a structured drawing style configuration.

[0038] The drawing range definition module is used to establish a drawing cube data structure based on the spatial range, cutting plane and drawing direction parameters input by the user, so as to accurately define the generation range of the two-dimensional drawing.

[0039] The parallel computing processing module contains an independently running hidden surface removal calculation engine and a sectioning calculation engine, which are used to perform hidden surface removal calculation and sectioning calculation on model objects located within the output cube, and generate hidden surface removal calculation results and sectioning calculation results respectively. Both the hidden surface removal calculation results and the sectioning calculation results carry the unique identifier of the model object.

[0040] The results grouping module is used to group the hidden surface removal calculation results and sectioning calculation results output by the parallel computing processing module according to the unique identifier of the model object, so as to prepare data for the core drawing process.

[0041] The merged plotting result generation module determines and merges adjacent result groups based on the "merged to" attribute, eliminates virtual boundaries in the model, and generates merged plotting results.

[0042] The style rendering and drawing generation module is used to assign drawing styles to the merged drawing results and generate final drawings that conform to engineering standards.

[0043] Preferably, the output style configuration module is configured as follows:

[0044] When the "Merge to" attribute is set to the name of its own style, the merging function of adjacent structures of the same style is enabled;

[0045] When set to the name of another drawing style, the current style inherits and uses the properties of the specified target style.

[0046] Preferably, the result grouping and organization module includes:

[0047] The result grouping unit is used to extract the unique identifiers attached to all geometric results and create independent result groups with each unique identifier as an index, merging the hidden surface removal calculation results and sectioning calculation results belonging to the same model object into the same result group;

[0048] The intra-group classification unit is used to further classify the hidden edge removal calculation results and the sectioning calculation results into three subsets according to type: visible edges, hidden edges, and section results within each result group.

[0049] A third objective of this invention is to provide an electronic device comprising:

[0050] Memory, used to store computer programs;

[0051] A processor is used to execute a program stored in memory to implement the steps of a structural drawing extraction method based on hidden line removal relationships as described above.

[0052] The fourth objective of this invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the structural drawing extraction method based on the blanking relationship described in any of the preceding claims.

[0053] The present invention provides a structural drawing extraction method based on hidden line removal relationships, which has the following significant advantages:

[0054] 1) The drawing generation has high accuracy and a high degree of automation.

[0055] By performing precise hidden surface removal calculations (combining back-side hidden surface removal and projection distance methods) and sectioning calculations on the model objects located inside the drawing cube, two-dimensional lines that accurately reflect the geometric information and spatial relationships of the three-dimensional model can be automatically generated. This completely avoids the workload and errors caused by manually handling hidden surface removal relationships, ensuring the accuracy of the drawings from the source.

[0056] 2) Effectively eliminate the discrepancy between the BIM model and the actual project, and improve the practicality of the drawings.

[0057] By introducing an innovative "merge to" attribute and a corresponding intelligent merging algorithm, the system can automatically identify and merge spatially adjacent structural groups that meet certain conditions. This eliminates virtual boundaries in the BIM model that do not exist in actual construction due to independent modeling (such as the intersection of beams and slabs in integral casting), ensuring that the generated two-dimensional drawings fully conform to the actual situation of integrated construction and significantly enhancing the guiding value of the drawings.

[0058] 3) It offers high flexibility in drawing output and good standardization.

[0059] With configurable drawing styles (unified definition of line types, fills, etc.) and flexible drawing cube definition methods (supporting multiple definitions such as bounding boxes, three points, and face elements), users can quickly generate drawings that meet the requirements of different drafting specifications (such as floor plans, elevations, and sections), and easily achieve complex sectioning effects such as stepped sections and polygonal sections, meeting the drawing needs of complex structures in infrastructure and other fields. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the three-dimensional model of the power plant building used in the embodiments of the present invention;

[0061] Figure 2 This is a flowchart illustrating an embodiment of a structural drawing extraction method based on hidden line removal relationships according to the present invention.

[0062] Figure 3 This is a schematic diagram illustrating the effect of the "merge into" attribute in an embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram of a concrete column model using the "Phase I Concrete-Column" drawing style in an embodiment of the present invention.

[0064] Figure 5 This is a schematic diagram of a concrete wall model using the "one-phase concrete-wall" drawing style, as shown in this embodiment of the invention.

[0065] Figure 6 This is a schematic diagram of a user interface for assigning drawing styles to structural objects in a 3D model according to an embodiment of the present invention.

[0066] Figure 7 This is a schematic diagram of the structure of the cube shown in the embodiment of the present invention, showing its six outer surfaces, cross-sections and drawing direction;

[0067] Figure 8 This is a schematic diagram illustrating the use of the "model bounding box method" to define the drawing cube and cross-section of the model in an embodiment of the present invention;

[0068] Figure 9 This is a schematic diagram illustrating the backface hidden removal algorithm used in the front-look hidden removal calculation according to an embodiment of the present invention;

[0069] Figure 10 This is a schematic diagram illustrating the use of the projection distance method in the forward-looking blanking calculation according to an embodiment of the present invention;

[0070] Figure 11 This is a schematic diagram illustrating the processing of the solid model by the sectioning calculation in an embodiment of the present invention;

[0071] Figure 12 This is a schematic diagram of result grouping in the geometric data organization step of an embodiment of the present invention;

[0072] Figure 13 This is a schematic diagram illustrating the classification of geometric results within the result grouping of an embodiment of the present invention;

[0073] Figure 14 This is a schematic diagram illustrating the determination of whether two result groups are spatially adjacent and meet the merging conditions in the intelligent result merging step of an embodiment of the present invention.

[0074] Figure 15 This is a schematic diagram of the facet merging operation in an embodiment of the present invention;

[0075] Figure 16 This is a schematic diagram showing the combined cross-sections of two adjacent columns according to an embodiment of the present invention;

[0076] Figure 17 This is a schematic diagram of the boundary merging operation in an embodiment of the present invention;

[0077] Figure 18 This is a rendering of the final 2D drawing generated according to an embodiment of the present invention;

[0078] Figure 19 This is a rendering of the final elevation drawing generated according to an embodiment of the present invention. Detailed Implementation

[0079] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0080] Terminology Explanation

[0081] Model object:

[0082] In a Building Information Modeling (BIM) or Computer-Aided Design (CAD) system, a discrete three-dimensional entity or element with a unique identifier is represented. These model objects are the basic semantic units that constitute a complete three-dimensional model, and each model object represents a building or engineering component with specific functions, types, and geometric attributes.

[0083] Model objects include, but are not limited to, the following types:

[0084] 1) Solid model objects: Three-dimensional solid components with volumetric features, such as beams, slabs, columns, walls, equipment foundations, etc.

[0085] 2) Two-dimensional graphic model objects: planar geometric elements defined in three-dimensional space, such as regions, filled areas, symbol markers, etc.

[0086] 3) Line Element Model Object: A linear geometric element used to represent edges, axes, or auxiliary lines.

[0087] Each model object is distinguished and managed by a unique identifier assigned by the system. This unique identifier remains unchanged throughout the model's lifecycle and is used to associate and map the geometric data and attribute information of the model object.

[0088] Hidden disappearance:

[0089] When projecting a 3D model onto a 2D plane, the process of removing obscured, invisible lines or surfaces avoids ambiguity and allows the 2D drawing to more clearly and accurately represent the structure of the 3D model. For example, when displaying a cuboid, the lines on the back side need to be hidden from a certain viewpoint and not shown in the 2D projection.

[0090] Visible edges:

[0091] From a specific perspective, the edges that can be directly observed in a 3D model are represented by solid lines in a 2D drawing. For example, when viewing a triangular prism from directly in front, the edges of the three faces facing us are the visible edges.

[0092] Hidden edges:

[0093] From a specific perspective, edges that are obscured by other parts and cannot be directly observed are usually represented by dashed lines in two-dimensional drawings. Continuing with the example of a triangular prism, when viewed from directly in front, the edges of the rear faces that are obscured by the front faces are called hidden edges.

[0094] profile:

[0095] A 3D model is cut open using an imaginary cutting plane, revealing a planar view of its internal structure. For example, in mechanical design, a sectional view is used to show the internal structure of a part.

[0096] Viewport:

[0097] The 2D image, after being projected and transformed in 3D space, is finally displayed in a rectangular area on the screen (or image buffer).

[0098] Style merging:

[0099] When style merging is enabled, adjacent structural lines are eliminated, and the sections are merged into one large section.

[0100] The core processing object of the method in this invention embodiment is the model object that constitutes the three-dimensional model. Each model object represents an independent component (such as a beam, slab, column, wall, etc.) with specific functions, types, and geometric attributes, and is assigned a unique identifier by the system that remains unchanged throughout the model's lifecycle. All subsequent operations, including drawing style configuration, hidden surface removal calculation, sectioning calculation, result grouping, and intelligent merging, are performed using these model objects as the basic unit.

[0101] Example 1

[0102] To better understand the improvements made by this invention compared to the prior art, this embodiment of the invention uses a power plant model drawing as an example to illustrate the specific implementation of the invention. The power plant model is as follows: Figure 1 As shown.

[0103] This invention provides a method for extracting structural drawings based on hidden line removal relationships, such as... Figure 2 As shown, it includes the following steps:

[0104] S1: Define and configure the drawing style for the model object to be drawn. The drawing style includes basic attributes, visible edge attributes, hidden edge attributes, section plane attributes, and the "merge to" attribute used to control the merging behavior of adjacent structural regions.

[0105] A drawing style includes the following attributes:

[0106] 1. Basic attributes: including the style name of the output style, the style associated layer, and the style associated material.

[0107] 2. Visible edge attributes: Defines the display style of edges (solid lines) that can be directly observed from a specific viewpoint, including the color, line type, and line width of visible edges.

[0108] 3. Hidden edge attribute: Defines the display style of edges (usually dashed lines) that are obscured by other parts and cannot be directly observed, including the color, line type, and line width of the hidden edge. The color and line width of the hidden edge can be the same as or different from the visible edge.

[0109] 4. Section plane attributes: These include section lines and fill patterns. Section lines include color, line type, and line width; the fill pattern defines the display style of the cut outline and its internal fill area when the model object is cut by a section plane, including color, line type, line width, and fill scaling ratio.

[0110] 5. "Merge to" property: Controls whether the current style inherits properties from other styles.

[0111] This attribute is one of the core innovations of this embodiment. It is used to control the regional merging behavior of adjacent structures in order to resolve the contradiction between independent modeling of BIM models and integrated construction in actual construction.

[0112] When the "Merge to" attribute is set to the name of its own style, the merging function of adjacent structures of the same style is enabled;

[0113] When the “Merge to” attribute is set to the name of another output style, the current style will inherit and use the attributes of the specified target style.

[0114] The "Merge to" attribute is illustrated below. This attribute is the core mechanism for merging adjacent areas, aiming to resolve the contradiction between components modeled independently in the BIM model for ease of design and statistics, and the integrated structure formed during actual construction.

[0115] For adjacent structures cast from the same material (such as concrete), such as slabs and beams, each component exists independently in the model for easy classification and statistics. However, in actual construction, beams and slabs are cast as a whole, and there is no physical boundary between adjacent parts. Therefore, when generating drawings, it is necessary to eliminate such virtual boundaries in the model so that the drawings conform to the actual construction.

[0116] If set to the name of its own style, the current style properties will take effect normally. When generating the drawing, the system will check all elements using this style. If they are spatially adjacent, they will be automatically merged into a continuous graphic, eliminating redundant boundary lines.

[0117] If the name is set to another output style, all property settings of the current style itself will be ignored, and the style will be fully inherited and rendered using the rules of the specified target style.

[0118] like Figure 3 As shown, Figure 3 (a) in the model is a 3D model where beams and slabs are independent components with clear boundary lines. However, in actual construction, there are no boundary lines between the top beams and slabs; instead, the beam-slab structure is integrally cast from concrete. Therefore, a "merge adjacent areas" setting is required to eliminate directly adjacent structural lines between beams and slabs during subsequent drawing processes, such as... Figure 3As shown in (b), the top surface of the beam and slab is cast as a whole without a dividing line.

[0119] This embodiment details the entire process of defining two drawing styles: "Phase I Concrete - Column" and "Phase I Concrete - Wall".

[0120] 1) Basic attributes:

[0121] Define the drawing style as "Phase I Concrete - Column", associate it with the material "Concrete", and associate it with the layer "CF_CN_YQZ". For example... Figure 4 As shown, the purple area represents all the concrete columns in the power plant model, which are all associated with the "CF_CN_YQZ" layer.

[0122] Define another output style as "Phase 1 Concrete-Wall", associate it with the material "Concrete", and associate it with the layer "CF_CN_YQQ". For example... Figure 5 As shown, the purple area represents all the concrete walls in the power plant model, which are all associated with the "CF_CN_YQQ" layer.

[0123] Similarly, drawing styles such as "Phase I Concrete - Large Volume", "Phase I Concrete - Beam", and "Phase I Concrete - Slab" can be added as needed for drawing output. These will not be elaborated on here.

[0124] 2) Visible edge attributes: The color of the visible edges of the “Phase I Concrete - Column” and “Phase I Concrete - Wall” is defined as No. 1, i.e. blue; the line type and line width of the visible edges are defined as No. 0, i.e. the thinnest continuous solid line.

[0125] 3) Hidden edge attributes: The color of the hidden edges of the “Phase I Concrete - Column” and “Phase I Concrete - Wall” is defined as No. 1, i.e., blue; the line type of the hidden edges is defined as No. 3; and the line width of the hidden edges is defined as No. 0.

[0126] 4) Section Surface Attributes: The section surface attributes of the "Phase I Concrete - Column" and "Phase I Concrete - Wall" include two types of attributes: section lines and fill patterns. The color of the section lines is defined as No. 1, i.e., blue; the line type and line width of the section lines are defined as No. 0. The fill patterns are all defined as "Reinforced Concrete"; the color of the fill patterns is defined as No. 2, i.e., green; the line type and line width of the fill patterns are defined as No. 0; the fill scaling ratio of the fill patterns is defined as 10, which represents the scaling factor of the fill pattern relative to the original size.

[0127] 5) "Merge to" attribute: The "Merge to" attribute of "Phase I Concrete - Column" is itself, which means that if two adjacent structures are both assigned the "Phase I Concrete - Column" style, then the adjacent areas of these two adjacent structures should be merged when the drawing is generated; The "Merge to" attribute of "Phase I Concrete - Wall" is "Phase I Concrete - Column", which means that all attributes defined by the "Phase I Concrete - Wall" style itself are invalid, and the definitions in the "Phase I Concrete - Column" style are used instead.

[0128] After defining the output styles, these styles need to be assigned to the corresponding structural objects (such as beams, slabs, columns, and walls) in the 3D model. Figure 6 As shown, select Figure 6 The purple area in the diagram represents the column. The system will pop up an attribute dialog box. In the attribute dialog box, configure the display style data. Select the display style data as the drawing style "Phase I Concrete - Column". This will assign the drawing style "Phase I Concrete - Column" to the column marked in the purple area.

[0129] The method for assigning drawing styles to other structural objects (such as beams, slabs, columns, and walls) is the same as the example above, and will not be repeated here.

[0130] S2: Based on the spatial range, cutting plane, and drawing direction parameters, establish a drawing cube to define the drawing range.

[0131] This step aims to create a drawing cube, which precisely defines the generation range, section planes, and drawing direction of the 2D drawing in the 3D model space.

[0132] The output cube is a three-dimensional spatial region enclosed by six outer surfaces, and it controls the content contained in the final drawing through a series of parameters. For example... Figure 7 As shown, the core parameters of the output cube include: the output plane position, and six range control parameters: vertical range, horizontal range, front view range, and rear view range. The vertical and horizontal ranges control the size of the output area, while the front and rear view ranges control the perspective depth. Each of the six range control parameters can be individually set to be on or off. The output plane position can be defined through viewport range, two points and view direction, and surface shape elements.

[0133] Within the cube, the purple plane is the cutting plane, and the drawing direction is defined by the green arrows. The direction the arrows point to is the front view area, and the opposite direction is the back view area.

[0134] The core functions of the output cube include:

[0135] 1) Spatial scope definition: Only the 3D model structure inside the drawing cube is calculated for drawing; the external model will be automatically clipped to ensure that the drawing content is focused on the target area.

[0136] 2) Section plane definition: The output cube contains a user-definable section plane used to cut the model to show its internal structure and construction.

[0137] 3) Definition of projection direction: By specifying the observation direction vector, the front and back view areas after sectioning are clearly defined, thereby determining the projection angle.

[0138] The method for creating the output cube in this embodiment includes one of the following three methods:

[0139] 1) Model Bounding Box Method. This method calculates the bounding box of the 3D model and generates section planes and drawing directions based on user-specified reference planes. After the user specifies a reference plane (such as the XY plane, YZ plane, or XZ plane), the system automatically calculates the overall spatial extent of the model and generates section planes at the center of the model bounding box. The drawing direction defaults to the negative direction of the coordinate axes along the selected reference plane. Figure 8 As shown, when generating a section plane (the plane enclosed by the purple line) for the power plant model based on the XY plane, the section plane is set at an elevation of 270M (the location of the turbine floor), and the output direction is the negative Z-axis direction (i.e., looking down). This method is simple to operate, efficient, and suitable for scenarios that require a quick display of the model's global sectional view.

[0140] 2) Three-point method. This method determines the cutting plane, forward viewing direction, and cutting depth by using three points specified by the user within the 2D view plane. Specifically, the first two points, combined with the current view plane, define a cutting plane, while the third point defines the forward viewing direction and cutting depth. The three-point method offers flexibility and precise positioning, making it suitable for complex scenarios with strict requirements on cutting position and viewing angle, such as when directional cutting is needed on complex internal structures of power plant buildings.

[0141] 3) Face Shape Element Definition Method. The shape of the cutting surface is directly defined using a user-defined plane or closed polyline, with the normal vector of this surface serving as the drawing direction. Users set the foreground and background depths through parametric input, thereby determining the final drawing cube range. For example, users can pre-draw a complex closed polyline aligned with the centerline of the generating unit within the power plant building. This face element allows for precise control of the drawing cube range, ensuring the sectioning results fully display all critical equipment and structures within the generating unit section.

[0142] In summary, this embodiment provides several drawing cube definition schemes, including the model bounding box method, the three-point method, and the face shape element definition method. These schemes complement each other in terms of operational efficiency and definition accuracy, achieving comprehensive coverage from fully automatic to semi-automatic to fully manual parametric definition. This effectively overcomes the shortcomings of insufficient applicability of a single method and significantly enhances the flexibility and practicality of the 3D model drawing function.

[0143] S3: Perform hidden surface removal calculation on the model object located inside the output cube, and generate the hidden surface removal calculation result, which carries the unique identifier of the model object.

[0144] Based on the output cube defined in step S2, hidden line removal calculations are performed on the front and back view regions of the output cube, respectively, to finally generate the hidden line removal result presented in the form of lines. This step and the subsequent step S4 are executed in parallel and are independent of each other.

[0145] S31: Perform hidden surface removal calculation on the front view area, including performing back face removal algorithm to remove unseen faces and filter out possible visible faces, and then performing projection distance method to determine the visibility of faces that have not been determined by the back face removal algorithm.

[0146] In the output cube, the output direction defines the viewpoint direction. During the forward-looking hidden surface removal calculation, the forward-looking direction vector V=(x, y, z) is used as the view vector, and the backface hidden surface removal algorithm and the projection distance method are used sequentially for hidden surface removal calculation. The steps include:

[0147] 1) Backface Hidden Face Removal Algorithm. This is the initial screening stage for projection calculation in this embodiment. The backface hidden face removal algorithm is used in this stage to quickly remove the absolutely invisible backfaces, retaining only the possibly visible facades and the frontfaces that are not judged in this stage. This efficiently filters out about 50% of the data, greatly improving the efficiency of subsequent precise hidden face removal calculations such as the projection distance method.

[0148] This algorithm quickly filters surfaces by calculating the normal vectors of all structural surfaces within the forward-looking region and comparing the angles between them and the view vectors. If the angle is acute, the surface is considered the back face and is invisible, so it is discarded. If the angle is right, the surface is considered the elevation, and its boundary appears as a visible edge in the hidden surface removal result.

[0149] like Figure 9 As shown, when performing front-view hidden surface removal calculations on the power plant building, the back side (red side) of the main beam structure is quickly removed, and its side side (blue side) is determined as the elevation, resulting in a straight line.

[0150] 2) Projection distance method. For faces that cannot be identified by the backface occlusion method, this embodiment uses the projection distance method for occlusion calculation. Based on the initial screening by the backface occlusion method, the projection distance method, as a precise occlusion calculation, can completely solve the visibility problem under complex occlusion relationships and ensure the accuracy of the results.

[0151] Extract all unhidden surfaces within the forward-looking region and project them onto the cutting plane. If the projection surface A' of surface A does not overlap with the projection surface of any other surface, then surface A is a visible surface, and all its structural edges are visible edges. If the projection surface A' intersects with the projection surface B', then within the intersection area, the surface region farther from the cutting plane is a hidden surface. This process is repeated to complete the hidden surface removal calculation.

[0152] In this embodiment, as Figure 10 As shown, between the main beam and the secondary beam in the power plant building, which have a projection overlap relationship (green overlapping area), the algorithm accurately calculates the top surface of the main beam that is obscured by the secondary beam (cyan area) as the hidden surface obtained after the hidden surface removal calculation.

[0153] S32: Perform hidden surface removal calculation on the back view area, including performing the back face hidden surface removal algorithm to remove unseen faces and filter out possible visible faces, and then performing the projection distance method to determine the visibility of faces that have not been determined by the back face hidden surface removal algorithm.

[0154] The algorithm flow for back-view hidden line removal calculation is exactly the same as that for front-view hidden line removal calculation. Both use the back-side hidden line removal method and the projection distance method for judgment in turn. The core difference is that the viewing direction vector used is opposite to that used in front-view hidden line removal calculation.

[0155] The reason for performing back-view hidden-hidden ...

[0156] The results of front-view and back-view hidden-hidden ...

[0157] S4: Perform sectioning calculations on the model object located within the output cube to generate sectioning calculation results, wherein the sectioning calculation results carry the unique identifier of the model object.

[0158] Based on the output cube defined in step S2, the model objects within the output cube are sectionalized and calculated. This step and step S3 are executed in parallel and are independent of each other.

[0159] This embodiment calculates the sectioning results by performing sectioning calculations on all model objects within the drawing cube's defined spatial range and the location of the sectioning plane, based on the sectioning plane's interaction with all model objects within the drawing cube's range. Appropriate processing rules are employed for different types of model objects to ensure the accuracy of the calculation results.

[0160] 1) Perform sectioning calculations on the solid model to generate closed polygonal cross-sections formed by the intersection of the solid model objects (such as beams, slabs, and columns) and the sectioning planes, as the sectioning calculation results. For example... Figure 11 As shown, Figure 11 (a) is the solid model of the turbine pier in the power plant building. When the cutting plane (XZ plane) is located at the center of its structure, the system calculates the purple polygonal region of the intersecting part, such as... Figure 11 In (b), the closed shape is the result of the sectioning calculation.

[0161] 2) Perform sectioning calculations on the two-dimensional graphic and generate line segments formed by the intersection of the two-dimensional graphic model object and the sectioning plane as the sectioning calculation results.

[0162] 3) Line element sectioning calculation: The intersection of the line element model object and the sectioning plane is generated as the sectioning calculation result.

[0163] Through the above differentiation process, this embodiment can accurately extract the geometric results generated by the intersection of various model objects and the cutting plane. All cutting calculation results carry the unique identifier of their corresponding dimensional model object. This structured geometric data will be sent to subsequent steps for processing along with the hidden surface removal calculation results, providing basic data for generating sectional views that conform to engineering standards.

[0164] S5: Group the results of hidden surface removal calculation and sectioning calculation based on the unique identifier of the model object.

[0165] The hidden surface removal calculation results obtained in step S3 and the sectioning calculation results obtained in step S4 (collectively referred to as geometric results, each carrying a corresponding unique identifier) ​​are analyzed to provide structured data for the core drawing process. This step includes two sub-steps: result grouping step S51 and intra-group classification step S52.

[0166] S51: Extract the unique identifier of the elements attached to all geometric results and create result groups using that identifier as an index.

[0167] The system iterates through all hidden edge removal calculation results (visible edges, hidden edges) and sectioning calculation results (section contours), and extracts the unique identifier of the corresponding model object from the metadata attached to each geometric result. The unique identifier is an unsigned integer. Then, the system uses each unique identifier as an index to create an independent result group for each model object, and stores all geometric results (such as lines and contours) belonging to that object into the corresponding result group.

[0168] In this embodiment, the model object with the unique identifier "121" is the turbine pier numbered 121 in the power plant building, such as... Figure 12 As shown in (a) above. All lines of the object obtained after hidden surface removal and sectioning calculations, as shown below. Figure 12 As shown in (b), the results will be merged into a group named "Group 121" for unified management, after which the hidden surface removal calculation will be performed. Figure 12 As can be seen in (b) of the diagram, all hidden edges have been removed after the hidden edges have been eliminated.

[0169] S52: Within each result group, classify the geometric results by type into visible edges, hidden edges, and tangent results.

[0170] Within each result group indexed by a unique identifier, the system further classifies them into three types based on the source and characteristics of each line:

[0171] 1. Visible edges: These are model contour edges that are determined to be visible from a specific viewpoint by S3 hidden line removal calculation.

[0172] 2. Hidden edge: refers to an edge that is determined to be occluded and invisible by S3 hidden edge removal calculation under a specific viewpoint.

[0173] 3. Section result: refers to the new edge (i.e., cross-sectional profile) formed by the intersection of the model and the section plane generated by the S4 section calculation.

[0174] Taking "Group 121" (hydro turbine pier) as an example, this group includes the visible edges of the structure's outer contour from the drawing perspective, the hidden edges obscured by the structure, and the cross-sectional results generated at the structure's section. For example... Figure 13 As shown, the red lines represent the cross-section results, the blue lines represent the visible edges, and the green dashed lines represent the hidden edges. Figure 13 (a) and Figure 13 (b) shows examples of classification results from two different perspectives.

[0175] After classification, lines of the same type are grouped into the same subset for storage, thus forming a clear and orderly data structure, which prepares for the subsequent style merging step S6 and style assignment step S7.

[0176] S6: Traverse the result groups, determine whether spatially adjacent result groups meet the merging conditions determined by the "Merge to" attribute in the output style, and perform a merging operation on adjacent result groups that meet the conditions to generate the merged output result.

[0177] This step is crucial for ensuring that the drawings accurately reflect the actual engineering project. It aims to eliminate virtual structural boundary lines in the BIM model that arise from independent modeling but do not exist in actual construction. Its core is based on the "Merge to" attribute in the output style defined in S1, which judges and merges spatially adjacent groups of results generated in S5. The specific steps are as follows:

[0178] S61: Traverse all result groups and determine whether spatially adjacent result groups meet the conditions for merging the output style.

[0179] The system iterates through all result groups generated in step S5 and detects result groups that are spatially adjacent. In this embodiment, for any two result groups, such as result group "Group 121" generated in step S5 and another result group "Group 122" also generated using step S5, the system determines whether they are spatially adjacent:

[0180] For a cross section, if two closed shapes share a common boundary in space, they are considered adjacent.

[0181] For visible and hidden edges, if two lines of the same type overlap in space, they are considered to be adjacent.

[0182] For spatially adjacent result groups, the system further determines whether their output style meets one of the following merging conditions:

[0183] Style consistency: The two groups use the same output style, and the "merge to" property of the style is set to itself.

[0184] Style inheritance: The "Merge to" property of the output style used by one group points to the output style used by another group, that is, there is an inheritance or reference relationship between the two.

[0185] For example, such as Figure 14 As shown, if both Group 121 (turbine pier) and Group 122 (pier base) use the "Phase I Concrete - Large Volume" style (and this style is "merged" into itself), or if the style of "Group 122" is set to be merged into the style of "Group 121", then they meet the merging condition.

[0186] S62: Perform region merging calculations on adjacent results that meet the merging conditions, eliminate redundant boundaries and merge geometries.

[0187] When adjacent groups meet the merging conditions, the system performs a precise geometric merge calculation:

[0188] 1. Section merging: Merges adjacent closed section shapes into a continuous, larger closed shape, eliminating redundant internal boundaries.

[0189] like Figure 15 As shown. Before being combined, the cross-sections of the turbine pier and the base have a clear dividing line, as shown... Figure 15 (a) In the merger, the dividing line was eliminated, forming a unified region. Figure 15 (b) in the middle.

[0190] like Figure 16 As shown. Two adjacent 400x400 main columns of the power plant building, as... Figure 16 As shown in (a), the cross-section is a closed square shape. The system merges them into a closed 800x400 rectangular shape, as shown in (a). Figure 16 As shown in (b) in the model, this eliminates the virtual boundary lines that exist in the model but not in actual construction.

[0191] 2. Boundary merging: For adjacent visible or hidden edges, their common parts are directly eliminated to achieve visual continuity of the area.

[0192] like Figure 17 As shown. In this embodiment, the power plant building's slabs and beams have two adjacent visible solid lines, as shown. Figure 17 As shown in (a), after boundary elimination calculation, the top surface areas of the slab and beam are merged, as follows: Figure 17 As shown in (b) of the diagram.

[0193] All geometric results processed in this step are called the output results, which are prepared for the final styling and drawing generation.

[0194] Step S7: Assign the style attributes defined in the drawing style to the output drawing results to generate the final drawing.

[0195] This step aims to render the merged output results generated in step S6 according to the output style defined in step S1. The system reads the output style definition associated with each output result, assigns corresponding display attributes to different categories of geometric elements in sequence, and finally completes the generation and output of the drawing. The specific steps are as follows:

[0196] S71: Assign style attributes to visible edges.

[0197] Based on the visible edge attribute configuration in the output style, set the color, line type, and line width for all visible edges in the output result.

[0198] In this embodiment, taking "Group 121" (hydro turbine pier) as an example, its bound drawing style is "Phase I Concrete - Large Volume". The system sets the visible edges in this group (such as the outer contour line of the pier body) to No. 1 blue, No. 0 continuous solid line and No. 0 line width.

[0199] S72: Assign style properties to the hidden edge.

[0200] Based on the hidden edge attribute configuration in the output style, set the color, line type, and line width for all hidden edges in the output result.

[0201] Taking "Group 121" as an example, the system sets the hidden edges in this group to blue (number 1), line type (number 3), and line width (number 0).

[0202] S73: Assign style attributes to the profile of the section plane.

[0203] Based on the section surface attribute configuration in the output style, set the color, line type, and line width for the outline of all section surfaces in the output result.

[0204] Let's continue with "Group 121" as an example. For the section profile in "Group 121" (such as the cross-sectional profile of the turbine pier), the system sets its profile line to blue line No. 1, continuous solid line No. 0, and line width No. 1.

[0205] S74: Assign a fill style to the section area.

[0206] Based on the section surface attribute configuration in the output style, set the fill pattern, fill color, and scaling ratio for the closed areas formed by all section surfaces in the output result.

[0207] Let's continue with "Group 121" as an example. Set the fill pattern of the section area (such as the concrete section of the turbine pier) in "Group 121" to "Reinforced Concrete" pattern, fill color to No. 2 green, and scale to 10 times.

[0208] S75: Complete the drawing layout and output the final file.

[0209] Write all the drawing objects (visible edges, hidden edges, section outlines and fills) after the above steps of style assignment into the drawing page, and perform final page setup, drawing frame insertion, scale adjustment and other layout operations to generate a finished drawing file that meets the engineering drawing standards.

[0210] The final output results generated by the example are as follows: Figure 18 and Figure 19 As shown. Figure 18 This is a floor plan. Figure 19 This is an elevation view.

[0211] Example 2

[0212] This embodiment provides a structural drawing extraction system based on hidden line removal relationships, used to implement the steps described in the above method embodiments.

[0213] 1. Rendering style configuration module.

[0214] This module defines and configures drawing styles for model objects to be drawn. These styles include basic attributes, visible edge attributes, hidden edge attributes, section plane attributes, and a "Merge to" attribute to control the merging behavior of adjacent structural regions. It provides users with a parameterized interface to generate structured drawing style configurations. This includes:

[0215] 1) Basic Attribute Configuration Unit: Used to set the style name, associated layers, and style associated materials for the output style.

[0216] 2) The visible edge attribute configuration unit is used to define the display style of the edges (solid lines) that can be directly observed from a specific viewpoint, including the color, line type, and line width of the visible edges.

[0217] 3) Hidden edge attribute configuration unit: used to define the display style of edges (usually dashed lines) that are obscured by other parts and cannot be directly observed, including the color, line type, and line width of the hidden edge. The color and line width of the hidden edge can be the same as or different from the visible edge.

[0218] 4) Section plane attributes: Used to define the section lines and fill patterns of the section plane. The section lines include color, line type, and line width; the fill pattern defines the display style of the cut outline and its internal fill area when the model object is cut by the section plane, including color, line type, line width, and fill scaling ratio.

[0219] 5) "Merge to" attribute configuration unit: As the core innovative unit of this system, it is used to configure the "Merge to" attribute; this unit is configured to: when the "Merge to" attribute is set to the name of its own style, enable the merging function of adjacent structures of the same style; when the "Merge to" attribute is set to the name of another output style, the current style will inherit and use the attributes of the specified target style.

[0220] 2. Drawing range definition module.

[0221] This module is used to establish a drawing cube data structure based on user-input spatial range, section plane, and drawing direction parameters to precisely define the generation range of the 2D drawing. It includes:

[0222] 1) Parametrically Defined Units: Provides multiple ways to define output cubes, including:

[0223] Model bounding box sub-unit: Used to automatically generate the output cube based on the model bounding box of the entire model.

[0224] Three-point sub-cell: Used to semi-automatically define a drawing cube by having the user specify three points within a two-dimensional view.

[0225] Face shape element definition sub-unit: used to manually and precisely define a cube using a user-defined plane or closed polyline.

[0226] 2) Spatial clipping unit: It is configured to calculate only the 3D model structure inside the output cube and automatically clip the external model.

[0227] 3. Parallel computing processing module.

[0228] This module contains two independently operating hidden surface removal calculation engines: a hidden surface removal calculation engine and a sectioning calculation engine. These engines perform hidden surface removal and sectioning calculations on model objects located within the output cube, generating both results. Both results carry a unique identifier for the model object. 1) Hidden Surface Removal Calculation Engine: This engine performs hidden surface removal calculations on the front and back view regions within the output cube. It uses a backface hidden surface removal algorithm for initial screening and a projection distance method for precise visibility determination, outputting hidden surface removal calculation results (visible edges and hidden edges) carrying the unique identifier of the model object.

[0229] 2) Sectioning Calculation Engine: Runs in parallel with the hidden surface removal calculation engine, and is used to perform sectioning calculations on model objects within the range based on the sectioning planes in the output cube, and outputs sectioning calculation results that also carry unique identifiers.

[0230] 4. Results grouping and organization module.

[0231] This module is used to group the hidden surface removal and sectioning calculation results output by the parallel computing processing module based on the unique identifier of the model object, preparing data for the core mapping process. It includes:

[0232] 1) Result grouping unit: used to extract the unique identifiers attached to all geometric results, and create independent result groups with each unique identifier as an index, merging the hidden surface removal calculation results and sectioning calculation results belonging to the same model object into the same result group.

[0233] 2) Intragroup classification unit: Used to further classify the hidden edge removal calculation results and the sectioning calculation results into three subsets according to type within each result group: visible edge, hidden edge, and section result.

[0234] 5. Module for generating graph results after merging.

[0235] This module is crucial for ensuring that drawings match the actual engineering project. It determines and merges adjacent result groups based on the "merge to" attribute, eliminates virtual boundaries in the model, and generates merged drawing results.

[0236] The module for generating merged graph results includes:

[0237] The merge condition judgment unit is used to traverse all result groups, detect spatially adjacent groups, and determine whether they meet one of the following merge conditions:

[0238] 1) Use the same output style and the "Merge to" property of that style is itself;

[0239] 2) The output style of one group is inherited from the output style of another group.

[0240] The output result merging calculation unit is used to perform merging operations on adjacent results that meet the merging conditions, including merging adjacent closed cutting surfaces into a continuous shape to eliminate internal boundaries, and eliminating the common parts of adjacent visible or hidden edges, and finally generating the merged output result.

[0241] 6. Style rendering and drawing generation module.

[0242] This module is used to assign drawing styles to the merged drawing results and generate final drawings that conform to engineering standards. Specifically, it includes:

[0243] 1) Style Assignment Unit: Used to assign corresponding display attributes to the merged output results according to the definitions in the output style configuration module, including setting styles for visible edges, hidden edges, and section outlines, as well as filling the section area with patterns.

[0244] 2) Drawing Layout and Output Unit: This unit is used to perform operations such as page layout, scale adjustment, and frame insertion on all rendered drawing objects, and to generate the final drawing file.

[0245] Example 3

[0246] This embodiment proposes an electronic device, including:

[0247] Memory, used to store computer programs;

[0248] The processor is used to execute the program stored in the memory to implement the steps of the above embodiment of the structural drawing extraction method based on the blanking relationship.

[0249] For details on the specific implementation of each step and related explanations, please refer to the aforementioned embodiment of a structural drawing extraction method based on hidden line removal relationships, which will not be repeated here.

[0250] The memory of the electronic device mentioned in this embodiment may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device.

[0251] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0252] Example 4

[0253] This invention also proposes a computer-readable storage medium storing a computer program. When executed by a processor, this computer program implements the steps of the above-described embodiment of the structural drawing extraction method based on hidden line removal relationships. For details on the specific implementation and explanation of each step of this method, please refer to the aforementioned embodiment of the structural drawing extraction method based on hidden line removal relationships; further elaboration will not be repeated here.

[0254] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A structural drawing extraction method based on blanking relationship, characterized in that, The method comprises the following steps: defining and configuring a drawing style for a model object to be drawn, the drawing style comprising basic attributes, visible edge attributes, hidden edge attributes, section surface attributes, and "merge into" attributes for controlling the merging behavior of adjacent structure regions; establishing a drawing cube according to the spatial range, section surface, and drawing direction parameters to define the drawing range; performing hidden surface removal calculation on the model object located inside the drawing cube to generate a hidden surface removal calculation result, the hidden surface removal calculation result carrying a unique identifier of the model object; performing section calculation on the model object located inside the drawing cube to generate a section calculation result, the section calculation result carrying the unique identifier of the model object; grouping the hidden surface removal calculation result and the section calculation result based on the unique identifier of the model object; traversing the result groups, judging whether the spatially adjacent result groups meet the merging conditions determined by the "merge into" attributes in the drawing style, and performing a merging operation on the adjacent result groups meeting the conditions to eliminate the virtual boundaries in the adjacent structure regions and generate a merged drawing result; assigning the drawing result with the style attributes defined in the drawing style to generate a final drawing; the merging conditions at least include any of the following cases: Case One: when the "merge into" attribute of the current drawing style is set as the name of another drawing style, the current drawing style will inherit and use the attributes of the other drawing style; when the "merge into" attribute of the other drawing style is set as the name of the same style, the merging function of the adjacent structure of the same style is enabled; Case Two: when the "merge into" attribute of the drawing style is set as the name of the same style, the merging function of the adjacent structure of the same style is enabled.

2. The method of claim 1, wherein, The establishment of the drawing cube comprises one of the following three methods: model bounding box method, generating a section surface and a drawing direction based on a user-specified reference surface by calculating the model bounding box of a three-dimensional model; three-point method, determining a section surface, a front view direction, and a section depth through three points specified by a user in a two-dimensional view plane; face shape element definition method, directly defining a section surface shape through a user-predefined plane or closed polyline, and taking the normal vector of the plane as the drawing direction.

3. The method of claim 1, wherein, The hidden surface removal calculation on the model object located inside the drawing cube comprises the following steps: performing hidden surface removal calculation on the front view region, including performing a back surface removal algorithm to remove invisible surfaces and screening out possible visible surfaces, and then performing a projection distance method to determine the visibility of surfaces not determined by the back surface removal algorithm; performing hidden surface removal calculation on the back view region, including performing a back surface removal algorithm to remove invisible surfaces and screening out possible visible surfaces, and then performing a projection distance method to determine the visibility of surfaces not determined by the back surface removal algorithm.

4. The method of claim 1, wherein, The section calculation on the model object located inside the drawing cube comprises at least one of the following methods: performing section calculation on a solid model to generate a closed polygonal section as the section calculation result, the closed polygonal section being generated by the intersection of the solid model object and the section surface; The sectioning calculation is performed on the two-dimensional graph to generate line segments intersected by the two-dimensional graph model object and the sectioning surface as the sectioning calculation result; The sectioning calculation is performed on the line element to generate intersection points of the line element model object and the sectioning surface as the sectioning calculation result.

5. A blanking relation based structural drawing extraction system, characterized by, The system comprises: A drawing style configuration module is configured to define and configure a drawing style for a model object to be drawn, the drawing style comprising basic attributes, visible edge attributes, hidden edge attributes, sectioning surface attributes, and a "merge into" attribute for controlling the merging behavior of adjacent structure regions, and to provide a parameterized interface for a user to generate a structured drawing style configuration; A drawing range definition module is configured to establish a drawing cube data structure according to the spatial range, sectioning surface and drawing direction parameters input by the user, to accurately define the generation range of the two-dimensional drawing; A parallel computing processing module comprises a blanking calculation engine and a sectioning calculation engine running independently of each other, and is configured to perform blanking calculation and sectioning calculation on the model objects located in the drawing cube to generate blanking calculation results and sectioning calculation results respectively, the blanking calculation results and the sectioning calculation results both carrying unique identifiers of the model objects; A result grouping organization module is configured to group the blanking calculation results and the sectioning calculation results output by the parallel computing processing module according to the unique identifiers of the model objects, to prepare data for the core drawing process; A post-merging drawing result generation module is configured to determine whether the spatially adjacent result groups meet the merging conditions determined by the "merge into" attribute of the drawing style configuration module based on the "merge into" attribute, to perform merging of the adjacent result groups, to eliminate the virtual boundaries in the adjacent structure regions, and to generate post-merging drawing results; A style rendering and drawing generation module is configured to assign the drawing style to the post-merging drawing results and to generate final drawings conforming to engineering standards; The merging conditions at least include any of the following cases: Case one: When the "merge into" attribute of the current drawing style is set to the name of another drawing style, the current drawing style will inherit and use the attributes of the other drawing style; When the "merge into" attribute of the other drawing style is set to the name of the same style, the merging function of the adjacent structures of the same style is enabled. Case two: When the "merge into" attribute of the drawing style is set to the name of the same style, the merging function of the adjacent structures of the same style is enabled.

6. The system of claim 5, wherein, The result grouping organization module comprises: A result grouping unit is configured to extract the unique identifiers attached to all geometric results, to create independent result groups indexed by each unique identifier, and to merge the blanking calculation results and the sectioning calculation results belonging to the same model object into the same result group; An intra-group classification unit is configured to further classify the blanking calculation results and the sectioning calculation results into three sub-sets of visible edges, hidden edges and sectioning surface results in each result group. 7.An electronic device comprising: a memory for storing a computer program; a processor for executing the program stored on the memory to implement the method steps of any one of claims 1-4.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the method steps in any one of claims 1-4.

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