Method and system for generating three-dimensional axial side graph based on BIM (Building Information Modeling), storage medium and equipment

Abstract

The invention provides a method and system for generating a three-dimensional axial side map based on BIM, a storage medium and equipment, and relates to the field of BIM modelling, and the method comprises the steps: obtaining an electromechanical pipeline BIM entity model of a target area, and extracting a longitudinal center positioning line as a line body model; by taking the end point of the line body model as a vertex, constructing four squares which share one side in pairs and are vertical to the plane of the three-dimensional shaft side view port on a plane vertical to the line body, and stretching along the line body to form a cuboid; independently projecting the line body model to obtain a center line in the front view direction; judging a center line shielding state based on a cuboid space position relation and executing blanking processing; and binding the blanking state with the space coordinates of the line body model to generate an axis-side system diagram. The method aims at solving the problems that in existing electromechanical pipeline BIM forward design, the manual drawing efficiency of a three-dimensional axial side drawing is low, entity model mapping line redundancy shielding is serious, positioning is difficult after simplification, and space relation distortion is caused by blanking algorithm failure.

Description

Technical Field

[0001] This invention relates to the field of BIM modeling, and in particular to a method, system, storage medium, and device for generating three-dimensional axonometric drawings based on BIM. Background Technology

[0002] BIM is the process, technology, and method of creating and utilizing digital models to manage and optimize the entire process of design, construction, and operation of construction projects. It is a three-dimensional model information integration technology developed on the basis of computer-aided design technology, and it is the digital carrier and visual expression of the physical characteristics and functional properties of building engineering.

[0003] A BIM software platform refers to a software platform for creating Building Information Modeling (BIM). It mainly provides a basic BIM engine to display 3D graphics. The BIM engine has the ability to combine different types of 3D graphics into various professional components such as architecture, structure, and equipment within a building, and at the same time provides the ability to set, edit, and statistically analyze the information attributes of 3D components.

[0004] A three-dimensional axonometric system diagram refers to a single-view projection perspective that simultaneously reflects the shape of an object on three coordinate planes on a single projection surface. It typically uses any vertex of a hexahedron in space as the center of the observation angle (e.g., ...). Figure 1 As shown, a three-dimensional (3D) is a system diagram that closely approximates human visual habits, possesses a strong sense of three-dimensionality, and highlights the three-dimensional image and spatial relationships of target components. However, due to the change in the three-dimensional perspective, the representation of the actual spatial relationships between BIM models becomes more complex. Axonometric views generally do not use actual measurements to reflect the true shape of each surface of an object; they are only used as an auxiliary perspective to illustrate the spatial situation of various mechanical and electrical branch pipes in three-dimensional space, and are used to draw diagrams that reflect this in two-dimensional drawings. Therefore, in BIM forward design, using 3D axonometric drawings can help engineering designers and construction personnel conceive and imagine the shape of objects, compensating for the shortcomings of orthographic projection drawings.

[0005] Currently, most BIM-based forward design drawings for MEP (Mechanical, Electrical, and Plumbing) systems rely on manual 3D isometric projection, which involves manually adjusting the viewing angle of the 3D model before annotation and drawing. Even software that automatically generates 3D isometric projections of MEP systems, due to the direct use of the original model, struggles to handle simplified spatial relationships from a 3D isometric perspective. This means the function cannot fully meet design requirements, with specific shortcomings as follows: 1. In the field of electromechanical engineering, direct drawing is performed from a 3D isometric perspective. Since the 3D BIM model in the perspective is a solid drawing model, there will be occlusion between different pipes. The 3D solid model has too many lines, which makes the spatial relationship of the components shown in the 3D isometric drawing complex and not concise or intuitive. It is impossible to see the pipe routing. Therefore, model simplification is required. 2. During the simplification process of the 3D pipe solid model, if it is directly converted into a 2D simplified line drawing, the same component will display multiple lines. For example, if a single circular pipe is converted into a single 2D line drawing, multiple lines will be generated at the same time, making it difficult to accurately locate. 3. The program cannot automatically filter out simplified electromechanical pipelines from complex 3D model projection lines because it cannot correctly handle the occlusion relationship of the simplified projection lines through the hidden line removal algorithm (not displaying the invisible parts that are blocked in the field of view). The output pipeline graphics cannot accurately represent the actual spatial relationship. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method, system, storage medium and device for generating three-dimensional axonometric drawings based on BIM. By simplifying the BIM solid model of electromechanical piping into a line model and combining it with a cuboid construction to realize spatial occlusion judgment, and accurately eliminating hidden lines based on the occlusion state of the center line in the frontal view direction, the invention solves the problems of redundant lines, difficult positioning and distorted spatial relationships in the axonometric drawings in the prior art, and greatly improves the efficiency of BIM forward design and optimizes the quality of drawings.

[0007] The technical solution adopted by this invention to solve its technical problem is: A method for generating 3D isometric views based on BIM is provided, including the following steps: S1: Obtain the BIM solid model of the electromechanical piping in the target area; and extract the longitudinal center positioning line of the BIM solid model of the electromechanical piping, and use the longitudinal center positioning line as the line body model; S2: Using one end of the line model as a vertex, construct four squares with two sides sharing the same side on a plane perpendicular to the line model. The side length of the square is equal to half the pipe diameter of the mechanical and electrical pipeline BIM solid model, and all four squares are perpendicular to the three-dimensional axial viewport plane. S3: Extend the four squares along the longitudinal direction of the line model to the other end of the line model to form four cuboids that are coplanar with each other and share the line model as their common edge. S4: Project the line model separately to form a center line segment that retains spatial coordinate information. Use the center line segment as the center line of the frontal view direction. The center line of the frontal view direction is parallel to the predetermined three-dimensional axisymmetric tilt view direction. S5: Based on the occlusion mechanism of the original three-dimensional spatial position coordinate relationship, determine the occlusion relationship between the four cuboids corresponding to the current electromechanical pipeline and the cuboids obtained by other electromechanical pipelines after processing by S1-S3, determine the occlusion state of the center line of the front view direction, the occlusion state includes completely occluded, partially occluded and not occluded, and perform hidden line removal processing on the center line of the front view direction according to the occlusion state; S6: Assign the hidden-suppression state information to the line model to bind the hidden-suppression state with the spatial coordinates of the line model and generate a three-dimensional isometric system diagram of the electromechanical pipeline.

[0008] Step S5 includes: 5.1 Call the coordinate reading interface of the BIM underlying engine to obtain the three-dimensional spatial coordinate dataset of the four cuboids corresponding to the current electromechanical pipeline and other electromechanical pipelines; 5.2. Based on the projection rules of the three-dimensional axonometric view, calculate the overlapping area of ​​the projection of the current cuboid and other cuboids on the three-dimensional axonometric viewport plane; 5.3 Compare the spatial positional relationship between the projected overlapping area and the center line of the viewing direction: if the projected overlapping area completely covers the center line of the viewing direction, it is determined to be "completely occluded"; if the projected overlapping area partially covers the center line of the viewing direction, it is determined to be "partially occluded"; if the projected overlapping area does not cover the center line of the viewing direction, it is determined to be "not occluded". 5.4. Perform hidden line removal operation according to the determined occlusion state: When the occlusion state is "completely occluded", remove the center line of the frontal direction from the display layer of the 3D isometric system diagram to achieve full hidden line removal; when the occlusion state is "partially occluded", locate the line segment on the center line of the frontal direction corresponding to the overlapping area of ​​the projection by coordinate matching, and set the display attribute of the line segment to "transparent" to achieve hidden line removal; when the occlusion state is "not occluded", maintain the original pixel attributes of the center line of the frontal direction and do not perform any hidden line removal operation.

[0009] The process also includes step S7: performing text and image adaptation processing on the generated 3D isometric system diagram of electromechanical piping. The specific steps are as follows: S7.1: Obtain the text box outline of the labeled text and the outer boundary outline of the equipment legend in the three-dimensional isometric system diagram, and encapsulate the text box outline and the outer boundary outline into independent integral graphic blocks respectively; S7.2: Based on the spatial positional relationship from a three-dimensional axonometric perspective, determine the occlusion relationship between each of the overall graphic blocks and the line model; S7.3: Following the occlusion judgment logic and hidden object removal operation rules of S5, perform hidden object removal on the line model parts that have an occlusion relationship with the overall graphic block to ensure that the annotation text and equipment legends are clearly displayed in the 3D isometric system diagram.

[0010] Step S1 further includes: receiving three-dimensional axonometric view parameters input by the user through the BIM software platform. The three-dimensional axonometric view parameters include the observation angle and the viewport range. The observation angle range is 0°-360°, and the viewport range is defined by pixel coordinates.

[0011] In step S2: The normal vectors of the four squares are consistent with the normal vectors of the three-dimensional axial viewport plane corresponding to the viewport range, and the distribution direction of the four squares is adapted to the observation angle to ensure that the cuboid is matched with the observation direction of the three-dimensional axial view after it is generated; adjacent squares share a complete edge, and the geometric centers of the four squares coincide with the endpoints of the line model, and the central axis of the four squares is collinear with the axis of the line model.

[0012] Step S3 specifically involves: stretching the four squares at a constant speed along the axis of the line model, keeping the side length and relative position of the squares unchanged during the stretching process, and ensuring that the stretching length is consistent with the actual length of the line model; after stretching, adjacent cuboids share a complete rectangular side surface, and one edge of each cuboid completely coincides with the axis of the line model.

[0013] A system for generating 3D axonometric drawings based on BIM, used to implement the method for generating 3D axonometric drawings based on BIM as described in any of the above claims, including: Model Acquisition and Simplification Module: Used to acquire the BIM entity model of the electromechanical pipeline in the target area, extract the longitudinal center positioning line of the BIM entity model of the electromechanical pipeline, and use the longitudinal center positioning line as the line body model; Cuboid construction module: Used to construct 4 squares with each pair of sides sharing a vertex on a plane perpendicular to the line model, with one end of the line model as the vertex, and extend the 4 squares along the longitudinal direction of the line model to the other end, forming 4 cuboids with each pair of sides sharing a common edge with the line model; Centerline generation module for frontal view: It is used to project the line model separately to form a centerline segment that retains spatial coordinate information, and define the centerline segment as a centerline for frontal view that is parallel to the predetermined three-dimensional axial tilt view direction; Occlusion Detection and Hidden Line Removal Module: Based on the occlusion mechanism of the original three-dimensional spatial position coordinate relationship, it determines the occlusion relationship between the four cuboids corresponding to the current electromechanical pipeline and the cuboids corresponding to other electromechanical pipelines, determines the occlusion state of the center line in the front view direction, and performs a hidden line removal operation on the center line in the front view direction according to the occlusion state. System diagram generation module: used to assign the hidden-suppression state information to the line model, realize the binding between the hidden-suppression state and the spatial coordinates of the line model, and generate a three-dimensional isometric system diagram of electromechanical pipelines.

[0014] It also includes a graphic occlusion adaptation module: used to obtain the text box outline of the labeled text in the 3D isometric system diagram and the outer boundary outline of the device legend and encapsulate them into an overall graphic block, determine the occlusion relationship between the overall graphic block and the line model, and trigger the occlusion judgment and hidden removal module to perform hidden removal processing on the occluded part of the line model according to the preset logic.

[0015] A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, it implements all the steps of the method for generating three-dimensional axonometric drawings based on BIM as described above.

[0016] An electronic device includes a processor, a memory, and a computer program stored in the memory, wherein the processor is connected to the memory via a data bus; when the processor invokes the computer program stored in the memory, it is able to execute all the steps of the method for generating three-dimensional axonometric drawings based on BIM as described above.

[0017] The beneficial effects of this invention are: The method, system, storage medium, and device for generating 3D isometric drawings based on BIM provided by this invention achieve multi-dimensional optimization through a complete technical path of "BIM entity model simplification - auxiliary cuboid construction - accurate spatial occlusion judgment - centerline hiding in the forward view direction - state and coordinate binding": First, it solves the problem of low efficiency in manual drawing by automating the isometric drawing generation process. It extracts the longitudinal center positioning line from the BIM entity model as a line body model, and then automatically completes the drawing through steps such as cuboid construction, projection to generate centerlines, occlusion judgment, and hidden line removal, significantly reducing manual operation costs and improving the efficiency of BIM forward design drawing output. Second, it overcomes the problem of redundant lines and severe occlusion in entity model drawings by simplifying the entity model with a line body model and using four cuboids strongly bound to the spatial position of pipes to assist in occlusion judgment, avoiding the ambiguity of pipe routing caused by excessive lines in the entity model, making the isometric drawing more concise and intuitive, and clearly presenting the spatial relationship of pipes. Third, it solves the problem of difficult positioning after model simplification by using four cuboids strongly bound to the spatial position of pipes. The cuboid and the linear model have collinear axes and coincident geometric centers, and their lengths are consistent with the linear model after stretching, ensuring precise binding of the cuboid and the pipeline's spatial position. This provides a reliable spatial reference for subsequent occlusion judgment and hidden line removal, avoiding positioning deviations after simplification. Fourth, it overcomes the defect of spatial relationship distortion caused by the failure of the hidden line removal algorithm. Based on the original three-dimensional spatial coordinate relationship, it judges the overlapping area of ​​the cuboid projection and performs differentiated hidden line removal processing based on the occlusion status (complete / partial / unoccluded) of the center line in the frontal view direction. This enables precise operations such as complete removal, partial transparency, or preservation of original attributes, ensuring that the output isometric system diagram accurately reflects the actual spatial relationship of the pipeline. In addition, through graphic and text adaptation hidden line removal processing, the annotation text and equipment legends are encapsulated into a whole graphic block. Hidden line removal is performed on the occluded parts of the linear model, ensuring clear display of graphics and text, further improving the practicality of the drawings, and helping engineering designers and construction personnel to more efficiently conceive and understand the shape and spatial layout of pipelines. This effectively makes up for the deficiencies of the orthographic projection drawing and optimizes the quality of the drawings and the engineering application value. Attached Figure Description

[0018] Figure 1 The cylinder (a) and cube (b) are shown from a three-dimensional axisymmetric view.

[0019] Figure 2 This is a schematic diagram of the state of the pipeline model before the simplification and hidden line removal in this invention.

[0020] Figure 3 This is a schematic diagram illustrating the state of the hidden line removal process of the center line in the frontal view direction according to the present invention.

[0021] Figure 4 This is a logic flowchart of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The "Method, System, Storage Medium, and Device for Generating 3D Axonometric Drawings Based on BIM" and "A Method for Generating 3D Axonometric Drawings Based on BIM" disclosed in this invention are based on a technical path of "BIM entity model simplification → cuboid construction → spatial occlusion judgment → centerline hiding in the frontal view → state binding" to achieve automated generation of 3D axonometric system drawings for electromechanical pipelines. The following detailed implementation process of the technical solution is illustrated with specific examples, using a real-world scenario of an underground machine room (including water supply and air conditioning water pipes) in a commercial complex. All operations are implemented based on the BIM software platform and built-in plugins, ensuring reproducibility by those skilled in the art, and the content focuses solely on the specified reference documents.

[0024] Basic conditions for implementation Software platform: Autodesk Revit 2024 (or an equivalent platform that supports BIM engine and API development) is used, with built-in plugins developed based on C# language and BIM underlying API (integrating five core modules: "model simplification", "cuboid construction", "occlusion detection", "hidden object removal", and "text and image adaptation", which conforms to the technical design of "built-in BIM software platform plugins"). Hardware environment: Intel Core i7-13700K processor, 32GB memory, NVIDIA RTX 4070 graphics card, meeting the requirements for smooth loading of BIM models and calculation of 3D coordinates; Basic data: BIM solid model of electromechanical pipelines in the target area (including complete attributes such as pipeline type, diameter, material, and spatial coordinates; the coordinate system adopts the commonly used engineering coordinate system such as the Beijing 54 coordinate system).

[0025] Specific implementation steps: as follows Figures 2-4 As shown Step S1: BIM Solid Model Acquisition and Line Simplification Using the FilteredElementCollector class (or equivalent interface) of the BIM software API, filter the BIM entity models of electromechanical pipelines within the target area (such as cylindrical water supply pipes and square air conditioning ducts); call the model attribute interface to extract the "longitudinal center positioning line" of the pipeline (along the pipeline axis, including the three-dimensional coordinates of the start / end point), and define it as a line model (to solve the problem of "redundant lines in the entity model"); obtain the three-dimensional axonometric view parameters input by the user through the plugin - observation angle (0°-360°, such as 30° / 45°) and viewport range (defined in pixels, such as 1920×1080), and pass the parameters to the BIM underlying engine to determine the normal vector of the axonometric viewport plane (perpendicular to the observation direction).

[0026] Step S2: Constructing the auxiliary cuboid Using any endpoint of the line model as a vertex, draw a square in a plane "perpendicular to the axis of the line model" (e.g., when the line extends along the Z-axis, the plane is the XY plane); all four squares are perpendicular to the three-dimensional axial viewport plane (the normal vector is consistent with the normal vector of the viewport plane), and their distribution direction is adapted to the observation angle; adjacent squares share a common side (share a complete side length), the geometric center of all four squares coincides with the endpoint of the line, and the central axis is collinear with the axis of the line.

[0027] Step S3: Extrude the square into a cuboid The model is stretched at a constant speed along its axis. During the stretching process, the side length and relative position of the square remain unchanged, and the stretching length is consistent with the actual length of the model. This forms four "pairwise coplanar" cuboids, with one edge of each cuboid completely coinciding with the axis of the model (ensuring a strong bond between the cuboids and the spatial position of the pipe).

[0028] Step S4: Generate the center line in the frontal view direction Using the View.Project interface (or equivalent projection function) of the BIM engine, the line model is projected separately onto the 3D axonometric viewport plane; the complete spatial coordinate information of the projected line segment is preserved, and the line segment is defined as the center line of the frontal view (the direction is parallel to the predetermined axonometric tilt view) as the sole reference for subsequent hidden surface removal judgment.

[0029] Step S5: Occlusion Detection and Precise Hidden Coverage The coordinate reading interface of the BIM underlying engine is called to extract the three-dimensional spatial coordinate datasets (each cuboid contains 8 vertex coordinates) of the "4 cuboids of the current pipeline" and the "4 cuboids of other pipelines after processing by S1-S3"; based on the orthographic projection rules of the three-dimensional axonometric view, the projection range of the current cuboid and other cuboids on the "axonometric viewport plane" is calculated, and then the projection overlap area is obtained; the spatial positional relationship between the "projection overlap area" and the "centerline of the frontal direction" is compared to determine 3 states: completely occluded: the projection overlap area completely covers the centerline of the frontal direction; partially occluded: the projection overlap area only covers a part of the line segment of the centerline of the frontal direction; not occluded: the projection overlap area does not cover the centerline of the frontal direction.

[0030] Differential processing is performed based on the judgment result, such as: completely occluded: remove the center line in the frontal direction from the display layer to achieve "complete occlusion"; partially occluded: locate the overlapping line segment by coordinate matching, set its display attribute to "transparent (100% transparency)", and only occluded segment is hidden; not occluded: maintain the original pixel attributes of the center line (such as black solid line, line width 0.3mm), and no operation is performed.

[0031] Step S6: Hidden state binding and system graph generation The plugin binds the "hidden state" (complete / partial / unobstructed) to the corresponding spatial coordinate segment of the line model through coordinate mapping; the plugin automatically integrates the line models and hidden states of all pipelines to generate a 3D isometric system diagram of electromechanical pipelines that conforms to GB / T50103-2010 "General Layout Drafting Standard", and supports exporting to DWG format.

[0032] Step S7: Image and text adaptation and hidden line removal To address the issue of occlusion by annotation text, equipment legends, and pipes, the "text box outline" of annotation text and the "outer boundary outline" of equipment legends in the system diagram are obtained, and both are encapsulated as independent "overall graphic blocks". Based on the spatial relationship of the axonometric view, the occlusion relationship between the overall graphic blocks and the line models is determined. Using the occlusion judgment logic and hidden line removal rules of S5, line segments that overlap with the graphic blocks are set to "transparent" to ensure that the text and legends are clearly displayed.

[0033] The specific usage method is as follows: Taking the generation of an isometric view of a cylindrical electromechanical pipeline (DN100 water supply steel pipe) as an example, the system adapts to the user-input three-dimensional isometric view parameters (observation angle 30°, viewport range 1920×1080 pixels, viewport plane parallel to the observer's screen) and executes steps S1-S7 in their entirety.

[0034] Step S1: The plugin uses the FilteredElementCollector class of the Revit API to filter and obtain the BIM entity model (cylinder) of "DN100 water supply steel pipe" in the computer room. The longitudinal center positioning line of the pipeline is extracted by calling the model attribute interface (along the pipeline axis, the starting coordinates are X=100.0m, Y=50.0m, Z=-5.0m, and the ending coordinates are X=110.0m, Y=50.0m, Z=-5.0m), and this positioning line is used as the line body model; The plugin receives the user's input of three-dimensional axonometric viewpoint parameters (observation angle 30°, viewport range 1920×1080 pixels), and automatically transmits the viewpoint parameters to the underlying engine to determine the normal vector of the axonometric viewport plane (perpendicular to the observation direction).

[0035] Step S2: Using the starting point of the line model (X=100.0m, Y=50.0m, Z=-5.0m) as the vertex, construct 4 squares on a plane perpendicular to the line model (i.e., the XY plane, since the line extends parallel to the Z-axis). Square parameters: Side length: equal to half the pipe diameter, i.e. 50mm (DN100 pipe inner diameter is 100mm). Spatial orientation: All four squares are perpendicular to the three-dimensional axial viewport plane (the normal vector is consistent with the normal vector of the viewport plane), and their distribution direction is adapted to a 30° observation angle; Positional relationship: Adjacent squares share a common side (sharing a complete 50mm side length), the geometric center of all four squares coincides with the starting point of the line body, and the central axis is collinear with the axis of the line body model (along the Z-axis direction).

[0036] Step S3: Four squares are stretched at a uniform speed along the axial direction of the linear model (from the starting point X=100.0m to the ending point X=110.0m); Stretching rules: During the stretching process, the side length (50mm) and relative position of the square remain unchanged, and the stretching length is consistent with the actual length of the line model (10m). Stretching result: Four pairwise coplanar cuboids are formed, with one edge of each cuboid completely coinciding with the axis of the linear model (along the Z-axis). The cross-section of each cuboid is a 50mm × 50mm square, and the length is 10m.

[0037] Step S4: The line model is projected separately onto the 3D axonometric viewport plane, and the spatial coordinate information of the projected line segment is preserved through the View.Project interface of the BIM engine; Define the projected line segment as the center line of the normal viewing direction, with its direction parallel to the predetermined 30° axial tilt viewing angle direction (projection coordinates of the line segment's starting point X=500 pixels, Y=300 pixels, and projection coordinates of the ending point X=1500 pixels, Y=300 pixels).

[0038] Step S5: 5.1 Obtaining the coordinate dataset Call the coordinate reading interface of the BIM underlying engine to obtain the three-dimensional spatial coordinate dataset of the four cuboids of the current DN100 water supply steel pipe, as well as the four cuboids of other pipes (such as DN150 air conditioning water pipe) after processing by S1-S3 (each cuboid contains the coordinates of 8 vertices).

[0039] 5.2 Calculation of Projection Overlap Area Based on the projection rules of a 30° axonometric view (using the "orthographic projection" algorithm), calculate the overlapping area of ​​the projections of the current water supply steel pipe cuboid and the air conditioning water pipe cuboid on the viewport plane: The rectangular projection range of the water supply steel pipe is: pixel coordinates (500, 280) - (1500, 320). The rectangular projection range of the air conditioning water pipe: pixel coordinates (800, 270) - (1200, 330); Overlapping area: pixel coordinates (800, 280) - (1200, 320).

[0040] 5.3 Determination of shading status Compare the positional relationship between the overlapping area and the center line in the frontal view direction (pixel coordinates 500,300-1500,300): The overlapping area (800, 280-1200, 320) partially covers the 800, 300-1200, 300 segment of the center line (400 pixels in length, corresponding to an actual pipe length of 4m), and is therefore determined to be partially occluded.

[0041] 5.4 Execution of Hidden Cut Operation Based on the determination result of "partially occluded", the overlapping line segment (800,300-1200,300) on the positioning center line is matched by coordinates, and the display attribute of the line segment is set to "transparent" (100% transparency) to achieve local occlusion.

[0042] Step S6: The status information of "partially occluded (800-1200 pixel segment transparent)" is bound to the corresponding spatial coordinate segment of the line model through coordinate mapping (actual pipe X=104.0m Y=50.0m Z=-5.0m to X=108.0m Y=50.0m Z=-5.0m). The plugin automatically integrates the line models and hidden state of all pipelines to generate a 3D isometric system diagram of electromechanical pipelines, which is exported as a DWG file (compliant with GB / T50103-2010 "General Layout Drafting Standard"). In the diagram, the 4m section of the DN100 water supply steel pipe that is covered is transparently displayed, while the remaining 6m retains the original pixel attributes (black solid line, line width 0.3mm).

[0043] Step S7: Obtain the outline of the text box for the label "DN100 water supply pipe" (pixel coordinates 600, 330-700, 350) and the outer boundary outline of the "gate valve" device legend (pixel coordinates 1100, 330-1150, 380) in the system diagram, and encapsulate them into independent graphic blocks. Based on the axonometric perspective spatial relationship, determine the occlusion between the graphic blocks and the line model: the text box outline covers the 650, 300-680, 300 segment of the centerline (corresponding to 0.3m of the actual pipe); the device legend outline does not cover the centerline. According to the S5 hidden line removal rule, set the 650, 300-680, 300 segment of the centerline to "transparent" to ensure that the label text is clearly displayed and avoid text and image occlusion.

[0044] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for generating 3D isometric views based on BIM, characterized in that: Includes the following steps: S1: Obtain the BIM solid model of the electromechanical piping in the target area; and extract the longitudinal center positioning line of the BIM solid model of the electromechanical piping, and use the longitudinal center positioning line as the line body model; S2: Using one end of the line model as a vertex, construct four squares with two sides sharing the same side on a plane perpendicular to the line model. The side length of the square is equal to half the pipe diameter of the mechanical and electrical pipeline BIM solid model, and all four squares are perpendicular to the three-dimensional axial viewport plane. S3: Extend the four squares along the longitudinal direction of the line model to the other end of the line model to form four cuboids that are coplanar with each other and share the line model as their common edge. S4: Project the line model separately to form a center line segment that retains spatial coordinate information. Use the center line segment as the center line of the frontal view direction. The center line of the frontal view direction is parallel to the predetermined three-dimensional axisymmetric tilt view direction. S5: Based on the occlusion mechanism of the original three-dimensional spatial position coordinate relationship, determine the occlusion relationship between the four cuboids corresponding to the current electromechanical pipeline and the cuboids obtained by other electromechanical pipelines after processing by S1-S3, determine the occlusion state of the center line of the front view direction, the occlusion state includes completely occluded, partially occluded and not occluded, and perform hidden line removal processing on the center line of the front view direction according to the occlusion state; S6: Assign the hidden-suppression state information to the line model to bind the hidden-suppression state with the spatial coordinates of the line model and generate a three-dimensional isometric system diagram of the electromechanical pipeline.

2. The method for generating three-dimensional axonometric drawings based on BIM as described in claim 1, characterized in that: Step S5 includes: 5.1 Call the coordinate reading interface of the BIM underlying engine to obtain the three-dimensional spatial coordinate dataset of the four cuboids corresponding to the current electromechanical pipeline and other electromechanical pipelines; 5.

2. Based on the projection rules of the three-dimensional axonometric view, calculate the overlapping area of ​​the projection of the current cuboid and other cuboids on the three-dimensional axonometric viewport plane; 5.3 Compare the spatial relationship between the projected overlapping area and the center line of the viewing direction: if the projected overlapping area completely covers the center line of the viewing direction, it is determined to be "completely occluded"; if the projected overlapping area partially covers the center line of the viewing direction, it is determined to be "partially occluded"; if the projected overlapping area does not cover the center line of the viewing direction, it is determined to be "not occluded". 5.

4. Perform hidden line removal operation according to the determined occlusion state: When the occlusion state is "completely occluded", remove the center line of the frontal view direction from the display layer of the 3D isometric system diagram to achieve full hidden line removal; when the occlusion state is "partially occluded", locate the line segment on the center line of the frontal view direction corresponding to the overlapping area of ​​the projection by coordinate matching, and set the display attribute of the line segment to "transparent" to achieve hidden line removal; when the occlusion state is "not occluded", maintain the original pixel attributes of the center line of the frontal view direction and do not perform any hidden line removal operation.

3. The method for generating three-dimensional isometric views based on BIM as described in claim 1, characterized in that: The process also includes step S7: performing text and image adaptation processing on the generated 3D isometric system diagram of electromechanical piping. The specific steps are as follows: S7.1: Obtain the text box outline of the labeled text and the outer boundary outline of the equipment legend in the three-dimensional isometric system diagram, and encapsulate the text box outline and the outer boundary outline into independent integral graphic blocks respectively; S7.2: Based on the spatial positional relationship from a three-dimensional axonometric perspective, determine the occlusion relationship between each of the overall graphic blocks and the line model; S7.3: Following the occlusion judgment logic and hidden object removal operation rules of S5, perform hidden object removal on the line model parts that have an occlusion relationship with the overall graphic block to ensure that the annotation text and equipment legends are clearly displayed in the 3D isometric system diagram.

4. The method for generating three-dimensional isometric views based on BIM as described in claim 1, characterized in that: Step S1 further includes: receiving three-dimensional axonometric view parameters input by the user through the BIM software platform. The three-dimensional axonometric view parameters include the observation angle and the viewport range. The observation angle range is 0°-360°, and the viewport range is defined by pixel coordinates.

5. The method for generating three-dimensional isometric views based on BIM as described in claim 4, characterized in that: In step S2: The normal vectors of the four squares are consistent with the normal vectors of the three-dimensional axial viewport plane corresponding to the viewport range, and the distribution direction of the four squares is adapted to the observation angle to ensure that the cuboid is matched with the observation direction of the three-dimensional axial view after it is generated; adjacent squares share a complete edge, and the geometric centers of the four squares coincide with the endpoints of the line model, and the central axis of the four squares is collinear with the axis of the line model.

6. The method for generating three-dimensional axonometric drawings based on BIM as described in claim 1, characterized in that: Step S3 specifically involves: stretching the four squares at a constant speed along the axis of the line model, keeping the side length and relative position of the squares unchanged during the stretching process, and ensuring that the stretching length is consistent with the actual length of the line model; after stretching, adjacent cuboids share a complete rectangular side surface, and one edge of each cuboid completely coincides with the axis of the line model.

7. A system for generating 3D isometric views based on BIM, characterized in that: This method is used to implement the BIM-based method for generating three-dimensional isometric views as described in any one of claims 1-6. include: Model Acquisition and Simplification Module: Used to acquire the BIM entity model of the electromechanical pipeline in the target area, extract the longitudinal center positioning line of the BIM entity model of the electromechanical pipeline, and use the longitudinal center positioning line as the line body model; Cuboid construction module: Used to construct 4 squares with each pair of sides sharing a vertex on a plane perpendicular to the line model, with one end of the line model as the vertex, and extend the 4 squares along the longitudinal direction of the line model to the other end, forming 4 cuboids with each pair of sides sharing a common edge with the line model; Centerline generation module for frontal view: It is used to project the line model separately to form a centerline segment that retains spatial coordinate information, and define the centerline segment as a centerline for frontal view that is parallel to the predetermined three-dimensional axial tilt view direction; Occlusion Detection and Hidden Line Removal Module: Based on the occlusion mechanism of the original three-dimensional spatial position coordinate relationship, it determines the occlusion relationship between the four cuboids corresponding to the current electromechanical pipeline and the cuboids corresponding to other electromechanical pipelines, determines the occlusion state of the center line in the front view direction, and performs a hidden line removal operation on the center line in the front view direction according to the occlusion state. System diagram generation module: used to assign the hidden-suppression state information to the line model, realize the binding between the hidden-suppression state and the spatial coordinates of the line model, and generate a three-dimensional isometric system diagram of electromechanical pipelines.

8. The system for generating three-dimensional axonometric drawings based on BIM according to claim 7, characterized in that, It also includes a graphic occlusion adaptation module: used to obtain the text box outline of the labeled text in the 3D isometric system diagram and the outer boundary outline of the device legend and encapsulate them into an overall graphic block, determine the occlusion relationship between the overall graphic block and the line model, and trigger the occlusion judgment and hidden removal module to perform hidden removal processing on the occluded part of the line model according to the preset logic.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements all the steps of the method for generating three-dimensional axonometric drawings based on BIM as described in any one of claims 1-6.

10. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory, wherein the processor and the memory are connected via a data bus; when the processor calls the computer program stored in the memory, it is able to execute all the steps of the method for generating three-dimensional axonometric drawings based on BIM as described in any one of claims 1-6.

Images