Visual file access method based on digital prototype

Abstract

The invention discloses a visual file access method based on a digital prototype. The method comprises the following steps: opening a model file of a specified type in a file stream form; analyzing a file header to judge whether the file format is a specified type of file format or not, if yes, reading a file version from the file header, judging whether the file version is a current version or not, if yes, obtaining all index table data, and finding an index table corresponding to the model data according to a data reading requirement; according to the position information of the index table corresponding to the model data, the file stream reading position is directly set to a designated position, and then the model data with the designated length is loaded according to the length information of the model data in the index table; and reading the model data according to a specified mode. According to the method, total elements are integrally designed through a single file, the data integrity is ensured, full-file analysis caused by local loading can be avoided, the access efficiency is improved, meanwhile, a data index chain keeps topological integrity, and a modular structure and dynamic extension are supported.

Description

Technical Field

[0001] This invention relates to the field of industrial digitalization technology, specifically to a method and computing device for accessing visualized files based on digital prototypes. Background Technology

[0002] The existing digital prototype format has significant flaws:

[0003] For example, current digital prototypes do not have a traditional format that simultaneously includes information such as mesh, topology, PMI (Product Manufacturing Information), materials, and design features, resulting in data gaps in digital prototypes. Furthermore, when reading traditional digital prototype format files, it is usually necessary to load and parse all the data, leading to loading redundancy.

[0004] In addition, since traditional digital prototypes store the complete assembly structure tree in traditional formats (such as STEP, IGES), any change to any component requires the entire assembly file to be regenerated, resulting in high update coupling. Especially in large assemblies (such as aircraft engines), local modifications can trigger a full update, taking several hours and resulting in low collaboration efficiency. At the same time, component updates lead to a chain of changes in multi-level assembly file versions, making version management complex.

[0005] On the other hand, the fixed structure and format of current digital prototypes are difficult to be compatible with new data types, resulting in poor scalability of digital prototypes. Summary of the Invention

[0006] One of the objectives of this invention is to address the technical problems of existing digital prototypes by providing a visualization file access method based on digital prototypes. The data format of this visualization file can support digital prototype applications at all stages of the product lifecycle, enabling unified structured storage of digital prototype data, supporting rapid local loading of model data, and allowing high-level assembly files referencing the component to be updated without modification when components are updated. This results in sufficient data information in the digital prototype, higher loading efficiency, stronger scalability, and more convenient version management.

[0007] To address the aforementioned technical problems, in a first aspect, embodiments of the present invention provide a visual file access method based on a digital prototype, the method comprising:

[0008] Open a model file of a specified type as a file stream;

[0009] The file header is parsed to determine if it is a specified file format. If so, the file version is read from the header and it is determined whether the file version is the current version. If so, all index table data is obtained, and the index table corresponding to the model data is found according to the data reading requirements.

[0010] Based on the location information of the index table corresponding to the model data, the file stream reading position is directly set to the specified position, and then the model data of the specified length is loaded according to the length information of the model data in the index table.

[0011] Read model data according to the specified method.

[0012] In a preferred embodiment, the model file is an assembly file or a part file.

[0013] In a preferred embodiment, the structure of the model file is as follows:

[0014] It consists of three parts: a file header, an index table, and multiple data blocks.

[0015] The file header is located at the beginning of the file and contains file format identifiers, file version information, and the number of index tables.

[0016] The index table follows the file header and consists of multiple index data entries. Each index data entry has a fixed storage length of 48 bytes and records the offset position and length of the document data block.

[0017] The data block is a collection of document data, each data block corresponds to an index, and the data block contains different types of data.

[0018] In a preferred embodiment, the data in the part file includes, but is not limited to: multi-level LOD model mesh data, model topology information, view information, material information, Product Manufacturing Information (PMI), design feature information or user-defined attributes, and also includes expandable information.

[0019] In a preferred embodiment, the assembly file includes attribute information of part files and a bill of materials (BOM) reflecting direct subordinate component references. The direct subordinate component references include: references to sub-part files, references to sub-assemblies, and the position of the sub-part or sub-assembly within the current assembly level.

[0020] In a preferred embodiment, an assembly structure tree is generated based on the assembly file. The assembly structure tree only records the direct subordinate component reference relationships of one level and does not recursively record multi-level tree structures. The node objects of the assembly structure tree store node ID, node name, node type, node attributes, node status, and node position.

[0021] In a preferred embodiment, when the model file being read is an assembly file, the assembly structure tree data in the assembly file is obtained;

[0022] Traverse the assembly structure tree to obtain the nth node;

[0023] Based on the name and type of the nth node's sub-component, locate the sub-component file in the specified directory;

[0024] Read the model LOD mesh information from the sub-file and move the model mesh to the position matrix in the nth node;

[0025] If it is of type eam, then continue the above process recursively, read the assembly structure tree of the eam file, and place the positions of the sub-components of the eam assembly superimposed on the position matrix of the current eam.

[0026] In a preferred embodiment, the method further includes:

[0027] Modify the model data, convert the original data stream into a new data stream, and obtain the length of the new data stream;

[0028] Delete the original data stream segment and update the file's index table;

[0029] Insert the new data stream into the position specified by the parameter index and update the index table again.

[0030] Secondly, in an embodiment of the present invention, a computing device is also provided, comprising a processor and a memory, the memory being used to store a computer program, the computer program including program instructions, and the processor being configured to invoke the program instructions to execute the method described above.

[0031] Thirdly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, the computer program including program instructions that, when executed by a processor or calculator, cause the processor to perform the method described above.

[0032] Compared with the prior art, the visual file access method based on digital prototype provided by the embodiments of the present invention has at least the following beneficial effects: it realizes the integration of all design elements through a single file, ensuring data integrity, avoiding full file parsing caused by partial loading and improving access efficiency, while the data index chain maintains topological integrity and supports modular structure to support dynamic expansion. In terms of updates, the actual measured update efficiency of millions of assemblies is improved by 40 times, and different teams can modify different subsystems in parallel. Attached Figure Description

[0033] The preferred embodiments will now be described in a clear and easy-to-understand manner, in conjunction with the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of the present invention.

[0034] Figure 1 This invention relates to a dual-file architecture for assembly files and part files.

[0035] Figure 2 This is a schematic diagram of the data structure of the part file in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the data structure of the assembly file in an embodiment of the present invention;

[0037] Figure 4 , 5 This is a schematic diagram of the file structure of the model file in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the assembly structure tree in an embodiment of the present invention;

[0039] Figure 7 This is a visual flowchart of the assembly file eam in an embodiment of the present invention;

[0040] Figure 8 This is a schematic diagram of a computing device structure according to an embodiment of the present invention. Detailed Implementation

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0042] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some figures, only one of components with the same structure or function is schematically depicted, or only one is labeled. In the embodiments of this invention, "one" not only means "only one," but can also mean "more than one." The following detailed description of the implementation of the technical solution of this invention will primarily use some specific embodiments as examples.

[0043] To achieve the objective of this invention, an embodiment of this invention provides a visual file access method based on a digital prototype, the method comprising:

[0044] Open a model file of a specified type as a file stream;

[0045] The file header is parsed to determine if it is a specified file format. If so, the file version is read from the header and it is determined whether the file version is the current version. If so, all index table data is obtained, and the index table corresponding to the model data is found according to the data reading requirements.

[0046] Based on the location information of the index table corresponding to the model data, the file stream reading position is directly set to the specified position, and then the model data of the specified length is loaded according to the length information of the model data in the index table.

[0047] Read model data according to the specified method.

[0048] In a preferred embodiment, the model file is an assembly file or a part file.

[0049] In a preferred embodiment, the structure of the model file is as follows:

[0050] It consists of three parts: a file header, an index table, and multiple data blocks.

[0051] The file header is located at the beginning of the file and contains file format identifiers, file version information, and the number of index tables.

[0052] The index table follows the file header and consists of multiple index data entries. Each index data entry has a fixed storage length of 48 bytes and records the offset position and length of the document data block.

[0053] The data block is a collection of document data, each data block corresponds to an index, and the data block contains different types of data.

[0054] Here, the file identifier can be a "magic number," such as "magic number: 0xE4F1." When reading the file, first check if this identifier is correct; if not, return an error directly.

[0055] In a preferred embodiment, the data in the part file includes, but is not limited to: multi-level LOD model mesh data, model topology information, view information, material information, Product Manufacturing Information (PMI), design feature information or user-defined attributes, and also includes expandable information.

[0056] In a preferred embodiment, the assembly file includes attribute information of part files and a bill of materials (BOM) reflecting direct subordinate component references. The direct subordinate component references include: references to sub-part files, references to sub-assemblies, and the position of the sub-part or sub-assembly within the current assembly level.

[0057] In a preferred embodiment, an assembly structure tree is generated based on the assembly file. The assembly structure tree only records the direct subordinate component reference relationships of one level and does not recursively record multi-level tree structures. The node objects of the assembly structure tree store node ID, node name, node type, node attributes, node status, and node position.

[0058] In a preferred embodiment, when the model file being read is an assembly file, the assembly structure tree data in the assembly file is obtained;

[0059] Traverse the assembly structure tree to obtain the nth node;

[0060] Based on the name and type of the nth node's sub-component, locate the sub-component file in the specified directory;

[0061] Read the model LOD mesh information from the sub-file and move the model mesh to the position matrix in the nth node;

[0062] If it is of type eam, then continue the above process recursively, read the assembly structure tree of the eam file, and place the positions of the sub-components of the eam assembly superimposed on the position matrix of the current eam.

[0063] In a preferred embodiment, the method further includes:

[0064] Modify the model data, convert the original data stream into a new data stream, and obtain the length of the new data stream;

[0065] Delete the original data stream segment and update the file's index table;

[0066] Insert the new data stream into the position specified by the parameter index and update the index table again.

[0067] This invention first defines a visualization data format based on digital prototypes, which can support digital prototype applications at all stages of the product lifecycle.

[0068] like Figure 1 As shown, the data format is applied to a dual-file architecture of assembly files (.eam) and part files (.ept). Figure 2 and 3 As shown, two file types are defined: assembly file (.eam) and part file (.ept);

[0069] Among them, such as Figure 2 The data stored in the part file (.ept) is shown below, including:

[0070] h) Multi-level LOD model grid data;

[0071] i) The topological structure information of the model, including the hierarchical relationship between volumes, faces, and edges;

[0072] j) View information;

[0073] k) Material information;

[0074] l) Product Manufacturing Information (PMI);

[0075] m) Design feature information;

[0076] n) User-defined attributes;

[0077] o) can also include other expandable information.

[0078] Topological data describes the connection and spatial relationships between geometric objects (volumes, faces, edges, points), defining relationships such as adjacency, connectivity, and containment between objects. It is the core data describing the inherent correlation of geometric structures.

[0079] For example, the table below:

[0080]

[0081] LOD grid data:

[0082] Model mesh data is a structured dataset that describes the surface geometry of a 3D object, consisting of three basic elements: vertices, edges, and faces.

[0083] LOD (Level of Detail) mesh data consists of mesh models of varying precision. The model precision is automatically switched based on the viewing distance or scene importance, significantly improving rendering performance while maintaining visual quality.

[0084] like Figure 3 As shown, the assembly file (.eam) stores additional information, including: attribute information from the part file (.ept); a BOM (Bill of Material) that reflects direct subordinate component references, which include: references to sub-part files, references to sub-assemblies, and the position of the component (sub-part or sub-assembly) in the current assembly (represented by a position matrix).

[0085] Since the assembly file only records references to its direct subordinate components, in terms of the update mechanism, if some of its subordinate component files change or are updated, the reference relationship remains unchanged and will not affect the assembly file itself.

[0086] like Figure 4 As shown, the file structure for each assembly file (eam) or part file (ept) is as follows:

[0087] It consists of three parts: a file header, an index table, and multiple data blocks.

[0088] The file header is located at the beginning of the file, with a fixed storage length of 40 bytes. It contains information such as file format identifier, file version information, and the number of index tables.

[0089] The index table follows the file header and consists of multiple index data entries. Each index data entry has a fixed storage length of 48 bytes and records information such as the offset position and length of the document data block.

[0090] A data block is a collection of document data. Each data block corresponds to an index and contains different types of data as defined above.

[0091] If a specific data type needs to be read, the corresponding data block is located directly through the index table, and the data is read. If a specific data type needs to be modified, the original data block is first deleted, the new data is rewritten at the original data block location, and the index table is updated.

[0092] Combination Figure 5 According to the preceding text and Figure 4 The file structure is defined as follows: the file structure is divided into three parts: file header, index table, and data blocks.

[0093] For example: File header (fixed length):

[0094] Magic number: 0xE4F1

[0095] Version number: 1.2

[0096] Number of indexed tables: 8

[0097] Data block index table:

[0098] Block 1: Type = Topology, Offset = 2048, Length = 4096

[0099] Block 2: Type = LOD1, Offset = 6144, Length = 8192 ...

[0101] Data block content area:

[2048] Topology data...

[6144] LOD1 grid data... The index table records information such as the data type, offset position, and length of document data blocks, enabling precise location and reading of data blocks. Its structure is as follows: struct Position { int data_type; int64 start_pos; int64 data_length; } After determining the part files and assembly files, this embodiment of the invention also defines the assembly structure, such as... Figure 5As shown, the assembly structure is a unique data type in the EAM file, used to describe the assembly structure tree of the assembly model. In this embodiment of the invention, the assembly structure is defined to be expressed by file reference, and the assembly structure tree only records one level and does not recursively record multiple levels of tree structure. like Figure 6 As shown, the top-level assembly A.eam only records references to subassemblies B.eam, part C.ept, and part D.ept, while the assembly B.eam file records references to parts D.ept and part E.ept. The assembly structure tree node object stores information such as node ID, node name, node type, node attributes, node status, and node position. Because the assembly structure is recorded through visual file references, and only one layer of the assembly structure is recorded, the data in the visual model can be decoupled from each other. This avoids a single change triggering a cascading update of a batch of files in the update mechanism, achieving "update only where changes are made," making updates easier. For example Figure 6 As shown, regarding part updates: both A.eam and B.eam reference D.ept. When the D model is updated, only a new D.ept file needs to be generated. The A.eam and B.eam files do not need to be changed, thus ensuring the correctness of the visualization of A.eam and B.eam. For assembly updates, if a new part F is assembled in B.eam, the assembly structure data of B.eam needs to be updated. The top-level assembly A.eam, which references B.eam, does not need to be changed, thus ensuring the correctness of A.eam's visualization. The main features of the dual-file architecture in this invention are as follows: Data is expandable: The current format supports data including: multi-level LOD (level of detail) meshes of the model, topology (volume / face / edge), material information, PMI information, design features, view information, parameter information, assembly structure, and user-defined attributes. As the demand for digital prototype applications increases in the later stages, the data can be expanded. Featuring an innovative assembly structure: the assembly file (.eam) only records direct references to lower-level components, rather than recording the entire assembly hierarchy. This design facilitates updating visual data; when a child component is updated, only the corresponding child component file needs to be updated, and all higher-level assembly files referencing that component do not need to be modified. It supports partial data read and write capabilities, allowing you to read and write specified data blocks as needed, avoiding full loading, thereby improving data read, write, and update efficiency. The embodiments of the present invention solve the technical challenges of data integrity storage for digital prototypes, efficient access to large models, and partial updates of large assemblies through structured storage and hierarchical decoupling design. The measured update efficiency of millions of assemblies is improved by 40 times. In the visualization file access of digital prototypes, partial data reading can be achieved. Taking reading the model parameter data of the ept model as an example, the steps are as follows: Step 1: Open the specified ept model file as a file stream; Step 2: Parse the file header to confirm that it is an ept file format. If not, return an error directly; otherwise, continue. Step 3: Read the ept file version from the file header, determine if the file version is the current version, if yes, continue; otherwise, proceed with the file upgrade process to upgrade the file, and continue after the upgrade. Step 4: Obtain all index table data. According to the requirements, find the index table data corresponding to the type data of the model parameters. Here, the model parameters can be of various types, including integers, booleans, floating-point numbers, and strings. During the CAD model design process, model attributes are often set in the model parameters, such as the model's material, density, and design time. Step 5: Based on start_pos in the model parameter data index, directly set the file stream reading position to the start_pos position to obtain parameter stream data of length data_length; As we know from the index table above, an index indicates the location of specific data. For example, to retrieve model parameter data, we first need to find the index of the model parameter data. Based on the location indicated by the index, we can quickly load the parameter data from the file. Step 6: Load model parameters based on model parameter data; Step 7: Close the ept model file. Taking the modification of the ept model parameters by writing ept model parameter information as an example, the steps are as follows: Step 1: Open the specified ept model file as a file stream; Step 2: Parse the file header to confirm that it is an ept file format. If not, return an error directly; otherwise, continue. Step 3: Read the ept file version from the file header, determine if the file version is the current version, if yes, continue; otherwise, proceed with the file upgrade process to upgrade the file, and continue after the upgrade. Step 4: Obtain all index table data and find the index table data corresponding to the parameter type data according to the requirements; Step 5: Based on start_pos in the parameter data index, directly set the file stream reading position to the start_pos position and obtain parameter stream data of length data_length; Step 6: Load model parameters based on parameter stream data; Step 7: Modify the model parameter data; Step 8: Convert the parameter data into a data stream and obtain the length of the stream data; Step 8: Delete the ept parameter data stream and update the file index table; Step 9: Insert the new parameter data stream into the specified position of the parameter index; Step 10: Update the index table; Step 11: Save and close the file. Assembly file (eam) example Automotive chassis assembly (chassis.eam) structure: For example, a mineral water bottle consists of two parts: a bottle cap and a bottle body. The bottle cap and the bottle body are two separate parts, which are two separate ept. files. The whole assembly is a single assembly file, which is the eam. file referred to in this embodiment of the invention. Now we need to assemble the bottle cap (.ept) and bottle body (.ept) into a bottle (.eam). The correct placement of the bottle cap and bottle body requires a proper position matrix. If the bottle cap is placed under the bottle body, the position matrix is ​​incorrect. This matrix describes the correct position (at the bottle opening) and orientation (opening of the bottle cap) of the bottle (.ept) within the bottle (.eam). The following is a visualization of the assembly process based on the assembly structure tree: like Figure 7 As shown, the assembly file EAM visualization workflow: Step 1: Obtain the assembly structure tree data in the assembly file according to the data reading process described above; Step 2: Traverse the assembly structure tree to obtain the nth node; Step 3: Based on the name and type of the nth node's sub-component, locate the sub-component file (eam / ept) in the specified directory; Step 3: Read the model LOD mesh information from the sub-file (eam / ept) and move the model mesh to the position matrix in the nth node; Step 4: If it is an .eam type, continue the above process recursively, read the assembly structure tree of the .eam file, and the placement of the sub-components of the .eam assembly needs to be superimposed with the position matrix of the current .eam. Thirdly, in an embodiment of the present invention, a computing device is also provided, the computing device including a processor and a memory, the memory being used to store a computer program, the computer program including program instructions, and the processor or calculator being configured to invoke the program instructions to execute the method described above. Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, the computer program including program instructions that, when executed by a processor or calculator, cause the processor or calculator to perform the method described above. like Figure 8 As shown in the figure, an embodiment of this application provides a computing device 1000, which includes a processor or calculator (not shown) 1001 and a memory 1002. The processor or calculator 1001 and the memory 1002 can be interconnected via a communication bus 1003. The communication bus 1003 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus 1003 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, the memory 1002 is used to store a computer program, which includes program instructions. The processor 1001 is configured to call the program instructions, and the program includes steps for executing some or all of the steps in the aforementioned methods. The processor 1001 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits used to control the execution of the above-mentioned program. The memory 1002 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or it may be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital versatile optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto. The memory may exist independently and be connected to the processor via a bus. The memory may also be integrated with the processor. The computing device 1000 may further include a communication module 1004 and a display 1005. The communication module 1004 can communicate with the optical tracking device. The communication module 1004 can be a wireless communication module (e.g., a WiFi module, a Bluetooth module, etc.) or a wired communication module. In addition, the computing device 1000 may also include general components such as communication interfaces (e.g., USB interfaces, microphone interfaces, etc.) and antennas, which will not be described in detail here. It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application. In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments. In the embodiments provided in this application, it should be understood that the disclosed system can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of 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 shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between systems or units may be electrical or other forms. 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. Furthermore, the functional units in the various embodiments of the application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software program module. If the integrated unit is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks. Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage device, which may include: a flash drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk, etc. The embodiments of this application have been described in detail above. Specific examples have been used in the embodiments of this invention to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application. It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for accessing a visualization file based on a digital mockup, characterized in that, The method comprises: opening a model file of a specified type in the form of a file stream; judging whether the file is of a specified type by parsing the file header, reading the file version from the file header if the file is of the specified type, judging whether the file version is the current version, obtaining all index table data if the file version is the current version, and finding the index table corresponding to the model data according to data reading requirements; directly setting the file stream reading position to a specified position according to the position information of the index table corresponding to the model data, and loading model data of a specified length according to the length information of the model data in the index table; reading the model data according to a specified mode.

2. The digital mockup-based visual file access method of claim 1, wherein, The model file is an assembly file or a part file.

3. The digital mockup-based visual file access method of claim 2, wherein, The structure of the model file is as follows: comprising a file header, an index table and a plurality of data blocks, wherein the file header is located at the beginning of the file and comprises file format identification, file version information and the number of index tables; the index table is followed by the file header and is composed of a plurality of index data, each index data has a fixed storage length of 48 bytes, and records the offset position and length of the document data block; the data block is a document data set, each data block corresponds to an index, and the data block comprises different types of data.

4. The digital mockup-based visual file access method of claim 3, wherein, The data of the part file includes but is not limited to: multi-level LOD model mesh data, model topology structure information, view information, material information, product manufacturing information PMI, design feature information or user-defined attributes, and also includes extensible information.

5. The digital mockup-based visual file access method according to claim 2 or 4, characterized by, The assembly file includes attribute information of the part file, a bill of materials BOM embodying direct subordinate component references, and the direct subordinate component references include references to sub-part files, references to sub-assembly files, and positions of sub-parts or sub-assemblies in the current assembly.

6. The digital mockup-based visual file access method of claim 5, wherein, An assembly structure tree is generated according to the assembly file, the assembly structure tree only records the direct subordinate component reference relationship of one layer and does not recursively record the multi-layer tree structure, wherein the node object of the assembly structure tree stores a node ID, a node name, a node type, a node attribute, a node state and a node position.

7. The digital mockup-based visual file access method of claim 6, wherein, When the read model file is an assembly file, the assembly structure tree data in the assembly file is obtained; the assembly structure tree is traversed to obtain an nth node; a sub-part file is found in a specified directory according to the sub-part name and the sub-part type of the nth node; model LOD mesh information in the sub-part file is read, and the model mesh is moved to the position matrix in the nth node; if it is an eam type, the above process is recursively continued to read the assembly structure tree of the eam file, and the positions of the sub-parts of the eam assembly are placed in the position matrix of the current eam.

8. The digital mockup-based visual file access method of claim 1, wherein, The method further comprises: performing a modification operation on the model data and converting the original data stream into a new data stream, obtaining the length of the new data stream; deleting the original data stream segment and updating the index table of the file; inserting the new data stream into the parameter index specified position and updating the index table again. ​ 9. A computing device, comprising: The computing device comprises a processor, a memory for storing a computer program comprising program instructions, the processor being configured to invoke the program instructions to perform the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program comprising program instructions which, when executed by a processor, cause the processor or a calculator to perform the method according to any one of claims 1 to 8.

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