Three-dimensional model file importing method and system

Abstract

The application discloses a kind of three-dimensional model file import method and system, for IGES / IGS file import, comprising: reading the three-dimensional model file to be imported to generate initial topology structure;The initial topology structure is repaired to obtain the intermediate topology structure of keeping geometric continuity;Intermediate topology structure is reconstructed to obtain optimized topology structure;Optimized topology structure is output, and file import is completed;Wherein, initial topology structure generation process includes, with dynamic tolerance instead of the default fixed tolerance of the three-dimensional model to be imported, and initial topology structure is generated according to dynamic tolerance.This application is aimed at the problems existing in the CAE process of IGES / IGS file import in the field of three-dimensional model, solves the defects of model analysis distortion caused by fixed tolerance in prior art.Through the method of the application, the accuracy of model import is effectively improved, and the integrity of complex models such as thin-walled parts, curved surface overlapping parts and the like after import is ensured.

Description

Technical Field

[0001] This invention relates to the field of automated simulation model conversion and construction, and in particular to a method and system for importing three-dimensional model files. Background Technology

[0002] When importing IGES / IGS models into simulation models, such as CAE software, there is a problem of insufficient topology repair. In particular, IGES / IGS files often suffer from geometric discontinuities (such as broken surfaces, gaps, and overlapping edges) due to data conversion or storage defects. Existing technologies only perform local repairs and cannot handle boundary errors in complex topologies (such as nested shells and non-manifold entities). Existing import techniques are too limited to fixed-tolerance IGES analytical methods, failing to address the issue of dynamic model size adaptation and lacking logic for topology reconstruction and type optimization. Summary of the Invention

[0003] To address the aforementioned issues, this application proposes a method and system for importing 3D model files.

[0004] The method of this application includes: a three-dimensional model file import method for IGES / IGS file import, comprising: reading the three-dimensional model file to be imported to generate an initial topology; performing basic repair on the initial topology to obtain an intermediate topology that maintains geometric continuity; reconstructing the intermediate topology to obtain an optimized topology; and outputting the optimized topology to complete the file import; wherein, the initial topology generation process includes, with dynamic tolerance... Replace the default fixed tolerance of the 3D model to be imported with the dynamic tolerance. Generate the initial topology.

[0005] The method in this application is further improved, the dynamic tolerance... The acquisition process includes:

[0006] ;

[0007] in This represents the geometric sub-tolerance based on model size and curvature sensitivity;

[0008] This represents the topological sub-tolerance that is dynamically adjusted based on topological complexity.

[0009] This represents the engineering constraint tolerance determined based on the actual application.

[0010] The method in this application is further improved, the aforementioned The acquisition process includes:

[0011] ;

[0012] in, , and The weighting coefficients are obtained through optimization using a genetic algorithm.

[0013] This represents the maximum value of the bounding box size of the model in the file to be imported;

[0014] Indicates overall curvature sensitivity; This represents the characteristic density.

[0015] The method in this application is further improved, the aforementioned The acquisition process includes:

[0016] ;

[0017] in, Let N be the maximum curvature among the two orthogonal principal curvatures at a point on the surface, and N be the number of samples.

[0018] The The acquisition process includes: ,in For the number of fixed points in the model, This represents the model volume.

[0019] The method in this application is further improved, the aforementioned The acquisition process includes:

[0020] ;

[0021] in, This represents the global scaling factor, used to control the baseline ratio of topology tolerance to geometric tolerance;

[0022] This represents the complexity sensitivity coefficient, used to adjust the rate at which the topological complexity C decays with respect to tolerance.

[0023] The , Obtained based on a genetic algorithm, where 'e' is the scientific notation symbol.

[0024] The method in this application is further improved, the aforementioned , satisfy:

[0025] ,

[0026] in, The weighting coefficient has a value range of 0 ≤ α ≤ 1;

[0027] Accuracy is an indicator of accuracy, which satisfies the following: ;

[0028] Efficiency is an efficiency metric that satisfies the following: ;

[0029] in, This represents the maximum allowable tolerance during the import process, where N is the number of samples. To calculate the absolute error between the actual value and the predicted value, t represents the actual calculation time. For reference time, The attenuation coefficient is and satisfies Where C satisfies , , , These represent the number of edges, faces, and shells of the model, respectively.

[0030] The method in this application is further improved, and the basic repair process for the initial topology includes: deleting duplicate vertices, merging collinear edges, and applying dynamic tolerance. Sew adjacent surfaces together.

[0031] The method of this application is further improved, and the process of reconstructing the intermediate topology includes:

[0032] If the current model is an entity, then preserve the entity's topology.

[0033] If the current model is a shell, check if the shell can be closed into a solid. If the verification passes, generate a solid. If the solidification fails, mark the defect reason and revert to a shell.

[0034] If the current model is a face, try to stitch it into a shell. If successful, check if the shell can be closed into a solid. If the verification passes, generate the solid. If the solidification fails, retain the original face, mark the defect cause, and revert to a shell.

[0035] If the current model is a line / edge, only the part associated with the higher geometry will be retained, isolated elements will be deleted, the number of references for sibling edges / lines will be adjusted, and only edges referenced by faces will be retained;

[0036] If a non-manifold topology exists, a local reconstruction is performed.

[0037] The method of this application is further improved, and the process of outputting the optimized topology includes: first exporting the complete entity, then the shell, and finally the face set.

[0038] This application also discloses a three-dimensional model file import system, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the methods described above.

[0039] This application addresses the problems existing in the import process of IGES / IGS files into CAE in the field of 3D models, and solves the defects of model analysis distortion caused by fixed tolerances in the prior art. The method of this application effectively improves the accuracy of model import and ensures the integrity of complex models such as thin-walled parts and overlapping curved surfaces after import. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a method flow provided in one embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of a conventionally imported part model provided in one embodiment of the present invention;

[0042] Figure 3 yes Figure 2 Enlarged view of the central area of ​​a traditional imported part model;

[0043] Figure 4 yes Figure 3 A diagram showing the specific defect locations in a traditionally imported part model;

[0044] Figure 5 For Figure 4 A schematic diagram illustrating the effect of repairing defects using the import method of this invention;

[0045] Figure 6 for Figure 5 Enlarged diagram of the defect repair location;

[0046] Figure 7 for Figure 2 A schematic diagram of the part model after importing it using the import method of this invention. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the following description, specific details such as particular system structures and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art should understand that this application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary details. It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0050] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0051] The present invention will now be described in further detail with reference to the accompanying drawings.

[0052] This invention is based on file parsing and reconstruction using Open CASCADE Technology (OCCT), and is applicable to the import and repair of geometric models in CAD / CAE / CAM systems, especially suitable for importing such models into CAE software. (See reference...) Figure 1 One embodiment of the method in this application. The method of this application includes: a three-dimensional model file import method for IGES / IGS file import, comprising: reading the three-dimensional model file to be imported to generate an initial topology; performing basic repair on the initial topology to obtain an intermediate topology that maintains geometric continuity; reconstructing the intermediate topology to obtain an optimized topology; and outputting the optimized topology to complete the file import; wherein, the initial topology generation process includes, with dynamic tolerance Replace the default fixed tolerance of the 3D model to be imported with the dynamic tolerance. Generate the initial topology.

[0053] During the import process of this application, OCCT is used to read the file and generate the initial topology. Basic repairs are performed, including deleting duplicate vertices, merging collinear edges, and tolerance-based adjustments. By suturing adjacent surfaces, an intermediate topological structure that maintains geometric continuity is obtained after repair.

[0054] During the reconstruction of the intermediate topology, the priority of part classification in the model is sorted from high to low (solid > shell > face > line > edge > point). In the reconstruction logic, if the current model is a solid, the solid topology is retained; if the current model is a shell, it is checked whether the shell can be closed into a solid. If the verification passes, a solid is generated; if the solidification fails, the defect reason is marked and it is returned to a shell; if the current model is a face, it is attempted to stitch it into a shell. If successful, it is checked whether the shell can be closed into a solid. If the verification passes, a solid is generated; if the solidification fails, the original face is retained, the defect reason is marked, and it is returned to a shell; if the current model is a line / edge, only the part associated with high-level geometry is retained, isolated elements are deleted, the reference count of sibling edges / lines is checked, and only edges referenced by faces are retained; if a non-manifold topology exists, local reconstruction is performed.

[0055] After reconstruction, the process of outputting the optimized topology includes: first exporting the complete solid, then the shell, and finally the face set. Prioritizing the export of the complete solid, followed by the shell, and finally the face set ensures the usability of downstream CAE analysis (such as finite element meshing).

[0056] The method in this application is further improved, the dynamic tolerance... The acquisition process includes:

[0057] ;

[0058] in This represents the geometric sub-tolerance based on model size and curvature sensitivity;

[0059] This represents the topological sub-tolerance that is dynamically adjusted based on topological complexity.

[0060] This represents the engineering constraint tolerance determined based on the actual application.

[0061] The method in this application is further improved, the aforementioned The acquisition process includes:

[0062]

[0063] in, , and The weighting coefficients are obtained through optimization using a genetic algorithm.

[0064] This represents the maximum value of the bounding box size of the model in the file to be imported;

[0065] Indicates overall curvature sensitivity; This represents the characteristic density.

[0066] The method in this application is further improved, the aforementioned The acquisition process includes:

[0067]

[0068] in, The maximum curvature among the two orthogonal principal curvatures at a point on the surface is given by N, which is the number of samples and is determined by both the curvature and the radius of curvature.

[0069] The The acquisition process includes: ,in For the number of fixed points in the model, This represents the model volume.

[0070] The method in this application is further improved, the aforementioned The acquisition process includes:

[0071] ;

[0072] in, This represents the global scaling factor, used to control the baseline ratio of topology tolerance to geometric tolerance;

[0073] This represents the complexity sensitivity coefficient, used to adjust the rate at which the topological complexity C decays with respect to tolerance.

[0074] The , Obtained based on a genetic algorithm, where 'e' is the scientific notation symbol.

[0075] The method in this application is further improved, the aforementioned , satisfy:

[0076] ,

[0077] in, The weighting coefficient has a value range of 0 ≤ α ≤ 1;

[0078] Accuracy is an indicator of accuracy, which satisfies the following: ;

[0079] Efficiency is an efficiency metric that satisfies the following: ;

[0080] in, This represents the maximum allowable tolerance during the import process, where N is the number of sample points. To calculate the absolute error between the actual value and the predicted value, t represents the actual calculation time. For reference time, The attenuation coefficient is and satisfies Where C satisfies , , , These represent the number of edges, faces, and shells of the model, respectively.

[0081] The above sampling process for the number of samples N includes: recording the size of the model bounding box when the model is imported, calculating the length of the diagonal of the model bounding box, and sampling according to a preset interval of the length, such as one-thousandth as the sampling interval; when the radius of curvature is zero, the sampling points are evenly distributed; if there are unevenly distributed areas, the number of sampling points is obtained by dividing the arc length by the sampling interval.

[0082] In this application, the engineering constraint sub-tolerance ( This allows users to determine the maximum / minimum tolerance limits based on their specific application.

[0083] , To set the minimum tolerance for input, This is the tolerance for the maximum input value.

[0084] In the actual import process, this application performs geometric feature analysis immediately after reading the IGES file: calculating the diagonal length L of the bounding box space, and inputting the sampling interval or using one-thousandth of the default setting L as the basic sampling interval. Then, a geometric quality assessment is performed, calculating the curvature distribution of each region of the model and performing continuity and geometric self-intersection checks. Intelligent sampling is conducted based on curvature and geometric features; the basic interval is used for uniform regions, and the number of sampling points in high-curvature regions is arc length / (basic interval * curvature factor). After obtaining the samples, dynamic tolerance calculation is performed according to the above embodiments of this application. The calculation results are retained, and the first stage of basic repair begins, cleaning the geometric data: redundant vertices that are duplicated or too close are deleted based on distance thresholds and normal consistency checks; segmented edges located on the same straight line are merged based on angle tolerance and projection checks; and adjacent surface patches are stitched into complete surfaces based on gap checks, eliminating minor gaps and overlaps. After completing the basic repair, the dominant type determination stage begins. First, valid entities (such as fully closed solid structures) are scanned and identified based on edge closure, normal consistency, and Euler property checks. If a valid entity is found, a region growing algorithm is used to further detect the existence of free, isolated shells based on connectivity analysis. When both exist (mixed state OutT), an isolation strategy is adopted: valid entities and free shells are processed separately, and the free shells are repaired independently before attempting integration. If no free shells exist, it is directly confirmed as a complete solid structure. If no valid entity is found in the initial scan, the search shifts to finding combinations of closed shells. When a closed shell is found, an attempt is made to solidify it into a solid structure: if solidification is successful, aspect ratio optimization is performed and the solid model is exported; if solidification fails, the shell structure is retained and the shell data is directly exported. In the case of neither valid entities nor closed shells, downgrading is performed: available facets and edge data are checked, and usable geometric information is extracted and exported as much as possible. Finally, all repair and transformation results are visualized by the rendering engine, presenting the repaired complete model. This multi-stage process ensures, through progressive repair and intelligent type judgment, the maximum possible recovery of usable geometric models from potentially defective IGES / IGS files.

[0085] This application also discloses a three-dimensional model file import system, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the methods described above.

[0086] This application addresses the problems existing in the import process of IGES / IGS files into CAE in the field of 3D models, and solves the defects of model analysis distortion caused by fixed tolerances in the prior art. The method of this application effectively improves the accuracy of model import and ensures the integrity of complex models such as thin-walled parts and overlapping curved surfaces after import.

[0087] Combination Figures 2-7This application further illustrates the process with accompanying drawings.

[0088] like Figures 2-4 In this context, the traditional import method is used for the files to be imported, such as... Figure 2 The 3D model file contains the following locations: seam locations, boundary locations, and intersection locations: Figure 3 It has many flaws and details. Figure 4 The highlighted portion suffers from defects in the import parsing process that cannot be avoided in traditional import methods due to differences in format, related algorithms, and model composition between the original drawing file and the imported new file.

[0089] The model imported in this application, such as Figure 5 , Figure 6 The status of repairs, Figure 7 The imported 3D model, obtained using the method described in this application, exhibits more detail, a higher number of feature points, and a higher feature retention rate. The method described in this application helps improve the repair rate of damaged surfaces. Compared to fixed tolerance, the dynamic tolerance of this invention allows for setting an appropriate tolerance value, resulting in a larger number of sampling points and a higher feature retention rate.

[0090] We analyzed models of different sizes ("large", "medium", and "small") using both traditional methods (without the tolerance adaptive algorithm proposed in this paper) and the method described in this paper. It can be seen that the models analyzed in this paper do not produce broken surfaces at the same location, demonstrating better robustness to models of different scales. Through a multi-stage topology reconstruction priority processing flow, the surface repair rate is significantly optimized. Compared to fixed tolerance, dynamic tolerance improves the feature preservation rate of the model.

[0091] Furthermore, this invention is simple to deploy, and the system hardware and software environment requirements are as follows:

[0092] Hardware configuration: x86_64 architecture processor (≥4 cores), 16GB memory, NVIDIA graphics card (supports OpenGL 3.3 and above).

[0093] Software dependencies: Open CASCADE Technology 7.7+, VTK 9.3, Qt 6.6.3 (for plug-in architecture), CMake build tool.

[0094] The dynamic tolerance adaptive calculation process includes:

[0095] Geometric subtotal tolerance calculation uses VTK bounding box calculation to obtain the size of the imported model's bounding box, and then calculates the maximum value of the model's bounding box size. The imported model is sampled on a surface, and the average principal curvature is calculated from 2 / 3 of the points. Based on the number of fixed points in the model and the calculated model volume, the feature density is obtained, and finally, the geometric tolerance is calculated. .

[0096] The topological tolerance was calculated using a genetic algorithm with a population size of 50, 100 iterations, a crossover probability of 0.8, and a mutation probability of 0.05.

[0097] objective function The imported test model is subjected to a union Boolean operation to calculate the accuracy value, and the processing time is recorded. Set the ideal reference time based on the scale of the imported model. Setting up the basics The value, According to the calculation formula and Obtain the attenuation coefficient Therefore, the efficiency is calculated based on the objective function. , The final value is obtained. .

[0098] The engineering constraint tolerance is calculated by inputting the user's maximum / minimum tolerance based on the accuracy requirements of the actual model, and finally obtaining the engineering constraint tolerance. .

[0099] In summary, based on the dynamic tolerance adjustment formula... This yields the actual required tolerance.

[0100] The refactoring process is as follows:

[0101] Phase 1: Initial Analysis and Basic Repair

[0102] The OCCT module reads the input file and injects the adaptive tolerance value generated by the dynamic tolerance calculation module. Basic repair operations include: deleting duplicate vertices within the tolerance range; merging collinear edges; stitching adjacent faces with a dynamic tolerance ε; and eliminating problems caused by fixed tolerances.

[0103] Phase 2: Geometric type-driven judgment

[0104] Entity-first detection path: By scanning SOLID types and verifying entity validity, the number of unreferenced free shells is counted for valid entities. When a free shell is detected, a mixed state flag of 0xFF is generated.

[0105] Shell and Degradation Path: If no valid entity is found, check the shell sealing and progressively downgrade the detection of surface / line / edge types;

[0106] Technical advantages: Compared with traditional single-path judgment, this solution achieves accurate identification of mixed topologies through status code 0xFF.

[0107] Phase 3: Differentiation Processing and Output

[0108] Standard entity / shell processing: Directly optimize and export complete entities, while attempting to enclose shells as entities; Dedicated channel for mixed states: Isolate effective entities to a protective container and independently repair free shells;

[0109] Final export.

[0110] This application implements all or part of the processes in the above embodiments, which can be accomplished by a computer program instructing related hardware. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a device / electronic device, recording media, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0111] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0112] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0113] In the embodiments provided in this application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device controller embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings or direct couplings or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0114] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0115] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0116] The scope of protection of this invention is not limited thereto. Any variations or substitutions of technical solutions that can be conceived without inventive effort should be included within the scope of protection of this invention. The scope of protection of this invention is determined by the claims.

Claims

1. A method for importing three-dimensional model files, characterized in that, For importing simulation models from IGES / IGS files, including: Read the 3D model file to be imported and generate the initial topology; Perform basic repairs on the initial topology to obtain an intermediate topology that maintains geometric continuity; Reconstruct the intermediate topology to obtain an optimized topology; The optimized topology will be output, and the file import will be completed. The initial topology generation process includes dynamic tolerance. Replace the default fixed tolerance of the 3D model to be imported with the dynamic tolerance. Generate the initial topology; The dynamic tolerance The acquisition process includes: ； in This represents the geometric sub-tolerance based on model size and curvature sensitivity; This represents the topological sub-tolerance that is dynamically adjusted based on topological complexity. This represents the engineering constraint sub-tolerance determined based on actual application. The The acquisition process includes: in, , and The weighting coefficients are obtained through optimization using a genetic algorithm. This represents the maximum value of the bounding box size of the model in the file to be imported; Indicates overall curvature sensitivity; Represents characteristic density; The The acquisition process includes: in, Let N be the maximum curvature among the two orthogonal principal curvatures at a point on the surface, and N be the number of samples. The The acquisition process includes: ,in For the number of fixed points in the model, For model volume; The The acquisition process includes: ； in, This represents the global scaling factor, used to control the baseline ratio of topology tolerance to geometric tolerance; This represents the complexity sensitivity coefficient, used to adjust the rate at which the topological complexity C decays with respect to tolerance. The , Obtained based on a genetic algorithm, where 'e' is the scientific notation symbol.

2. The method according to claim 1, characterized in that, The , satisfy: ， in, The weighting coefficient has a value range of 0 ≤ α ≤ 1; Accuracy is an indicator of accuracy, which satisfies the following: ; Efficiency is an efficiency metric that satisfies the following: ; in, This represents the maximum allowable tolerance during the import process, where N is the number of samples. To calculate the absolute error between the actual value and the predicted value, t represents the actual calculation time. For reference time, The attenuation coefficient is and satisfies Where C satisfies , , , These represent the number of edges, faces, and shells of the model, respectively.

3. The method according to claim 1, characterized in that, The basic repair process for the initial topology includes: deleting duplicate vertices, merging collinear edges, and applying dynamic tolerance. Sew adjacent surfaces together.

4. The method according to claim 1, characterized in that, The process of reconstructing the intermediate topology includes: If the current model is an entity, then preserve the entity's topology. If the current model is a shell, check if the shell can be enclosed into a solid. If the verification passes, generate a solid. If the solidification fails, mark the defect reason and revert to a shell. If the current model is a face, try to stitch it into a shell. If successful, check if the shell can be closed into a solid. If the verification passes, generate the solid. If the solidification fails, retain the original face, mark the defect cause, and revert to a shell. If the current model is a line / edge, only the part associated with the higher geometry will be retained, isolated elements will be deleted, the number of references for sibling edges / lines will be adjusted, and only edges referenced by faces will be retained; If a non-manifold topology exists, a local reconstruction is performed.

5. The method according to claim 1, characterized in that, The process of outputting the optimized topology includes: first exporting the complete entity, then the shell, and finally the face set.

6. A three-dimensional model file import system, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor, when executing the computer program, implements the method as described in any one of claims 1 to 5.

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