AR application method and system based on Bentley software modeling

Abstract

The invention provides an AR (Augmented Reality) application method and system based on Bentley software modeling. According to the method, a DGN file is converted into an iModel file through Bentley View, and a model analysis program is developed by utilizing iModel.js, Node.js and Typescript. The analysis process comprises the steps of obtaining a model database snapshot, traversing a physical object, obtaining geometric and material information and attribute information, and finally outputting a GLTF file to be loaded by an AR application. According to the method, the DGN data is converted into the data type which can be identified by the AR application in a low-cost and lossless analysis mode, the application scene of the AR is expanded, and the modeling efficiency and the information accuracy in the AR application are improved.

Description

Technical Field

[0001] The present invention relates to the field of AR application technology, and in particular to an AR application method and system based on Bentley software modeling. Background Art

[0002] In recent years, as the digital needs in the infrastructure field continue to evolve, Bentley has played an important role as a core modeling software supplier for BIM (Building Information Modeling), and its products are widely used in the design, construction and operation of infrastructure such as roads, bridges, railways, water services, and electricity. However, DGN, as a unique output format of Bentley software, cannot be directly read and loaded by AR applications, resulting in data island problems.

[0003] There are three main ways to deal with the above problems in the existing technology. The first is to carry out secondary development of Bentley software to achieve data conversion. On the one hand, this method requires the authorization of Bentley software, and on the other hand, it needs to be continuously iterated with the update of Bentley software version, and the investment cost is relatively high. The second is to convert the model into a common model format, generally IFC, through the export function of Bentley software, and then parse IFC to obtain model data, but there is a problem of map loss in this method. The third is to purchase a third-party SDK to directly parse the DGN format, which is relatively expensive. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes an AR application method and system based on Bentley software modeling, which solves the transmission problem of Bentley model data in a low-cost and lossless way, thereby realizing loading and display in AR applications. The present invention specifically provides the following technical solutions: An AR application method based on Bentley software modeling, the method comprising the following steps: Step 1: Open the Bentley View application, use the Bentley View to open the DGN file, and publish the DGN file as an iModel file; Step 2: Use iModel.js to build a model parsing program, use Node.js as the development environment, Typescript as the development language, and install the iModel.js method library through npm; The analysis process specifically includes the following steps: Step 2.1: Get a snapshot of the model database through the openFile function of the SnapshotDb class; Step 2.2: traverse all physical objects in the model database through the withPreparedStatement function in the snapshot in step 2.1; Step 2.3: Obtain the geometry and material information of the physical object through the exportGraphics function in the snapshot in step 2.1, wherein each physical object includes one or more ExportGraphicsInfo, and each ExportGraphicsInfo includes the geometry information and material information of a mesh, wherein the geometry information includes vertices, normals, index lists, and texture coordinate information; the material information includes color, texture, and rendering mode information; Step 2.4: Obtain the attribute information of the physical object through the getAspects function of the elements attribute in the snapshot in step 2.1, wherein each physical object contains one or more ElementAspects, each ElementAspect represents a set of attributes, and traverse each attribute through forEachProperty to obtain complete attribute information; Step 3: Output the parsing result as a GLTF file and load it in the AR application.

[0005] Optionally, the format definition of the GLTF file includes nine core parts, and the core parts specifically include scene, node, mesh, accessor, buffer view, buffer, material, texture, and image.

[0006] Optionally, the relationship between the core parts specifically includes: The physical object described in step 2.2 corresponds to the node in the GLTF file; The grid described in the step 2.3 corresponds to the mesh in the GLTF file, the geometric information of the grid is stored in the buffer of the GLTF file in binary form, and is accurately matched through the buffer view and the accessor, and the object of the material information of the grid corresponds to the material in the GLTF file, the mapping information in the material corresponds to the texture in the GLTF file, and the image data is also stored in the buffer of the GLTF file in binary form and is associated in the image of the GLTF file.

[0007] Optionally, in step 2.2, an ECSQL statement is used to traverse the physical objects in the model database, and the ECSQL statement is SELECT ECInstanceId FROM bis.SpatialIndex.

[0008] Optionally, the AR application also supports OBJ and FBX format file output.

[0009] Optionally, the loading process of the AR application includes the following steps: Step 4.1: Initialize the GLTF loader in the AR application and configure the loader parameters to support asynchronous loading; Step 4.2: Call the load function of the loader, pass in the path of the GLTF file, and start loading the model data; Step 4.3: After loading is complete, use the AR framework to render the model into the real world, specifically including setting the position, rotation, and scale of the model; the AR framework is ARCore.

[0010] Optionally, the AR application supports real-time interaction, specifically including the following steps: Step 5.1: Setting a touch event listener in the AR application to detect the user's touch operation; Step 5.2: According to the touch position of the user, count the interactions with the model in the AR scene, where the interactions specifically include selection, dragging, and zooming operations; Step 5.3: Apply user interaction operations to the model and update the model status in real time; The updating model also includes version control of the model data, specifically including: Step 5.3.1: Generate a new version number and record the update log every time the model data is updated; Step 5.3.2: Provide a user interface for users to view and select different versions of model data; Step 5.3.3: Load the selected version of the GLTF file in the AR application for display.

[0011] Optionally, the step 3 further includes optimizing the performance of the AR application, specifically including the following steps: Step 6.1: During the model loading process, use LOD technology to dynamically adjust the model's level of detail based on the user's perspective and distance; Step 6.2: Implement a model culling mechanism to avoid rendering model parts outside the user's field of view to improve rendering efficiency; Step 6.3: Use GPU acceleration technology and Instancing technology to reduce the number of draw calls to optimize the rendering process of the model.

[0012] Optionally, the method is applied to design and construction scenarios of roads, bridges, and power infrastructure.

[0013] The present invention also provides an AR application system based on Bentley software modeling, the system comprising: Bentley View module, which is used to open DGN files and publish them as iModel files; The model parsing module is built based on iModel.js, using Node.js as the development environment and Typescript as the development language. The iModel.js method library is installed through npm. The module includes: The snapshot acquisition unit obtains a snapshot of the model database through the openFile function of the SnapshotDb class; A physical object traversal unit, which traverses all physical objects in the model database through the withPreparedStatement function in the snapshot; A geometry and material information extraction unit, which obtains geometry and material information of a physical object through the exportGraphics function in the snapshot, wherein each physical object contains one or more ExportGraphicsInfo, and each ExportGraphicsInfo contains geometry information and material information of a mesh; An attribute information acquisition unit, which acquires attribute information of a physical object through the getAspects function of the elements attribute in the snapshot, wherein each physical object contains one or more ElementAspects, and traverses each attribute through forEachProperty to acquire complete attribute information; GLTF file output module, used to output the parsing results as GLTF files and load them in AR applications; User interface module, used to display AR content and interact with users; The data storage module is used to store the parsed model data and user interaction records.

[0014] The present invention has the following beneficial technical effects: The present invention provides an AR application method and system based on Bentley software modeling. By converting DGN files into iModel files and further parsing them into GLTF format, the problem of loading and displaying Bentley model data in AR applications is effectively solved, and data loss and texture loss are avoided. Compared with the prior art, the present invention does not require secondary development of Bentley software or purchase of high-cost third-party SDKs, thereby significantly reducing implementation costs and maintenance costs. The model parsing program built using iModel.js and Node.js can quickly and efficiently extract the geometry and material information of the model, ensuring that high-quality 3D models can be loaded and displayed in real time in AR applications. The AR application of the present invention not only supports the GLTF format, but can also be extended to support other general model formats such as OBJ and FBX, thereby enhancing the flexibility and applicability of the system. By setting a touch event listener, users can interact with the models in the AR scene in real time, including selection, dragging and scaling operations, thereby improving the user experience. The present invention also provides a version control function for model data, so that users can easily view and select different versions of model data, ensuring that model changes can be tracked and managed during the design and construction process. At the same time, by using LOD technology, model culling mechanism and GPU acceleration technology, the rendering efficiency and performance of AR applications are significantly improved, ensuring that they can still run smoothly in complex scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A flowchart of loading a Bentley model in an AR application is provided in an embodiment of the present invention.

[0017] Figure 2 A model parsing flow chart provided for an embodiment of the present invention.

[0018] Figure 3 An interface diagram for publishing an iModel file provided in an embodiment of the present invention.

[0019] Figure 4 A real-life picture of a Bentley model loaded in an AR application provided in an embodiment of the present invention.

[0020] Figure 5 The core definitions and interrelationship diagram in the GLTF file provided for the embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] The following specific examples of the markings are used to illustrate the embodiments of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0023] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any labeled structures and / or functions described herein are merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number and aspect set forth herein may be used to implement an apparatus and / or practice a method.

[0024] It should also be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present application.

[0025] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these marked details.

[0026] The purpose of the present invention is to provide an AR application method and system based on Bentley software modeling, which aims to convert DGN data into a data type that can be recognized by AR applications in a low-cost and lossless parsing method, which can help architecture, engineering and construction AEC-related companies reduce costs and increase efficiency, expand the application scenarios of AR, and improve customer satisfaction with model AR applications.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Reference Figure 1, showing an embodiment of the present application, this embodiment will take the conversion of DGN format to GLTF as an example to realize the loading of Bentley model in AR application.

[0029] Step 1: Open the Bentley View application, use the Bentley View to open a DGN file, and publish the DGN file as an iModel file.

[0030] Specifically, the specific process of publishing is as follows Figure 3 As shown, specifically: Install and open the Bentley View application; in the menu bar of Bentley View, click the File menu; select the Open option; in the file selection dialog box that opens, find the DGN file, select it, and then click Open; after opening the DGN file, view and edit the file content; in the menu bar of Bentley View, click the File menu; in the drop-down menu, select the Publish option, and in the submenu, select the iModel option; in the pop-up Publish to iModel dialog box, set the name of the iModel and other options; enter the name of the iModel; select the location to save the iModel; select other options as needed, such as the element types and properties included. After confirming that all settings are correct, click the Publish button to start the conversion process. Once the publishing process is completed, find the generated iModel file in the specified save location.

[0031] Step 2: Use iModel.js to build a model parsing program, use Node.js as the development environment, Typescript as the development language, and install iModel.js through npm.

[0032] Preferably, the parsing process is as follows Figure 2 As shown, the specific steps include: Step 2.1: Get a snapshot of the model database through the openFile function of the SnapshotDb class; Step 2.2: traverse all physical objects in the model database through the withPreparedStatement function in the snapshot in step 2.1; Step 2.3: Obtain the geometry and material information of the physical object through the exportGraphics function in the snapshot in step 2.1, wherein each physical object includes one or more ExportGraphicsInfo, and each ExportGraphicsInfo includes the geometry information and material information of a mesh, wherein the geometry information includes vertices, normals, index lists, and texture coordinate information; the material information includes color, texture, and rendering mode information; Step 2.4: Get the property information of the physical object through the getAspects function of the elements attribute in the snapshot in step 2.1, where each physical object contains one or more ElementAspects, each ElementAspect represents a property set, and traverse each property through forEachProperty to obtain complete property information.

[0033] Preferably, in the step 2.2, an ECSQL (Element Component Structured Query Language) statement is used to traverse the physical objects in the model database, and the ECSQL statement is SELECTECInstanceId FROM bis.SpatialIndex.

[0034] Preferably, the extracted data can be losslessly compressed, preferably using the LZ77 algorithm, and the specific steps are as follows: Input data: D = {d1, d2, ..., dn}; Output compressed data: C = Compress(D), where the Compress function is the LZ77 compression algorithm, di is the i-th data element, and n is the total number of data elements; Convert the compressed data into a format recognizable by the AR application. Input the compressed data C and output the AR format data: A = ConvertToARFormat(C). The ConvertToARFormat function converts the data structure into the format required by the AR application, such as GLTF.

[0035] Step 3: Output the parsing result as a GLTF (Graphics Library Transmission Format) file and load it in the AR application.

[0036] The format definition of the GLTF file includes nine core parts, which specifically include scene, node, mesh, accessor, buffer view, buffer, material, texture, and image.

[0037] Exemplarily, a scene Scene refers to a collection of all objects in a 3D environment; a node Node represents a node in a scene graph, which usually contains a transformation matrix and references to child nodes, meshes, etc.; a mesh Mesh consists of vertices, edges, and faces, and is used to construct the shape of a 3D object; an accessor Accessor is used to access vertex data, such as position, normal, texture coordinates, etc. Material Material defines the surface characteristics of an object, such as color, texture, lighting model, etc. BufferView is a view of the data in the buffer, usually used to store mesh, material and other data; Texture Texture is image data, which is used to map to the surface of a 3D object. Buffer is where raw data is stored, such as vertex data, index data, etc.; Image Image is used to represent image resources for textures.

[0038] The relationships among the above nine core parts are as follows: Figure 5 As shown, specifically including: The physical object described in step 2.2 corresponds to the node in the GLTF file; The grid described in the step 2.3 corresponds to the mesh in the GLTF file, the geometric information of the grid is stored in the buffer of the GLTF file in binary form, and is accurately matched through the buffer view and the accessor, and the object of the material information of the grid corresponds to the material in the GLTF file, the mapping information in the material corresponds to the texture in the GLTF file, and the image data is also stored in the buffer of the GLTF file in binary form and is associated in the image of the GLTF file.

[0039] Preferably, the loading process of the AR application includes the following steps: Step 4.1: Initialize the GLTF loader in the AR application and configure the loader parameters to support asynchronous loading; Step 4.2: Call the load function of the loader, pass in the path of the GLTF file, and start loading the model data; Step 4.3: After loading is complete, use the AR framework to render the model into the real world, specifically including setting the position, rotation, and scale of the model; the AR framework is ARCore.

[0040] Preferably, the AR application also supports real-time interaction, such as Figure 4 As shown, the specific steps include: Step 5.1: Setting a touch event listener in the AR application to detect the user's touch operation; Step 5.2: According to the touch position of the user, count the interactions with the model in the AR scene, where the interactions specifically include selection, dragging, and zooming operations; Step 5.3: Apply user interaction operations to the model and update the model status in real time; The updating model also includes version control of the model data, specifically including: Step 5.3.1: Generate a new version number and record the update log every time the model data is updated; Step 5.3.2: Provide a user interface for users to view and select different versions of model data; Step 5.3.3: Load the selected version of the GLTF file in the AR application for display.

[0041] Preferably, step 3 further includes optimizing the performance of the AR application, specifically including the following steps: Step 6.1: During the model loading process, use LOD (Level of Detail) technology to dynamically adjust the model's level of detail based on the user's perspective and distance; Step 6.2: Implement a model culling mechanism to avoid rendering model parts outside the user's field of view to improve rendering efficiency; Step 6.3: Use GPU acceleration technology and Instancing technology to reduce the number of draw calls to optimize the rendering process of the model.

[0042] Preferably, the method is applied to the design and construction scenarios of roads, bridges, and power infrastructure; exemplarily including: in the design stage, using AR technology to display the visualization effect of the design scheme to help designers make evaluations; in the construction stage, using AR technology for on-site construction guidance, and real-time comparison of the design model with the actual construction situation; in the maintenance stage, using AR technology to conduct facility inspections and maintenance records to improve maintenance efficiency.

[0043] Optionally, the AR application also supports OBJ and FBX format file output. The AR application can be but is not limited to smartphones, tablet computers and servers, AR / VR glasses, external sensors and other devices.

[0044] The present application also provides an AR application system based on Bentley software modeling, the system comprising: Bentley View module, which is used to open DGN files and publish them as iModel files; The model parsing module is built based on iModel.js, using Node.js as the development environment and Typescript as the development language. The iModel.js method library is installed through npm. The module includes: The snapshot acquisition unit obtains a snapshot of the model database through the openFile function of the SnapshotDb class; A physical object traversal unit, which traverses all physical objects in the model database through the withPreparedStatement function in the snapshot; A geometry and material information extraction unit, which obtains geometry and material information of a physical object through the exportGraphics function in the snapshot, wherein each physical object contains one or more ExportGraphicsInfo, and each ExportGraphicsInfo contains geometry information and material information of a mesh; An attribute information acquisition unit, which acquires attribute information of a physical object through the getAspects function of the elements attribute in the snapshot, wherein each physical object contains one or more ElementAspects, and traverses each attribute through forEachProperty to acquire complete attribute information; GLTF file output module, used to output the parsing results as GLTF files and load them in AR applications; User interface module, used to display AR content and interact with users; The data storage module is used to store the parsed model data and user interaction records.

[0045] For example, the data storage stores the loaded model data in the local cache for quick loading next time. SQLite database is preferred to store model data. For example, CREATE TABLE ModelData (id INTEGER PRIMARYKEY, data BLOB); at the same time, data encryption technology is used to protect model data for security assurance, such as using the AES algorithm to encrypt model data: Encrypt(data, key)Decrypt(encrypted_data, key).

[0046] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a computer device, including: at least one processor; and The memory stores a computer program that can be run on the processor, and the processor executes the steps of any of the above methods for testing database performance when executing the program.

[0047] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a computer-readable storage medium, which stores computer program instructions. When the computer program instructions are executed by a processor, the steps of any one of the above management methods are performed.

[0048] Finally, it should be noted that a person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only storage memory (ROM) or a random access memory (RAM), etc. The above-mentioned computer program embodiments can achieve the same or similar effects as the corresponding above-mentioned arbitrary method embodiments.

[0049] In addition, typically, the devices and equipment disclosed in the embodiments of the present invention may be various electronic terminal devices, such as mobile phones, personal digital assistants (PDAs), tablet computers (PADs), smart TVs, etc., or large terminal devices, such as servers, etc. Therefore, the protection scope disclosed in the embodiments of the present invention should not be limited to a certain type of device or equipment. The client disclosed in the embodiments of the present invention may be applied to any of the above electronic terminal devices in the form of electronic hardware, computer software, or a combination of the two.

[0050] In addition, the method disclosed in the embodiment of the present invention can also be implemented as a computer program executed by a CPU, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by the CPU, the above functions defined in the method disclosed in the embodiment of the present invention are performed.

[0051] In addition, the above method steps and system units may also be implemented using a controller and a computer-readable storage medium for storing a computer program that enables the controller to implement the above steps or unit functions.

[0052] In addition, it should be understood that the computer-readable storage medium (e.g., memory) herein can be a volatile memory or a non-volatile memory, or can include both a volatile memory and a non-volatile memory. As an example and not by way of limitation, a non-volatile memory can include a read-only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), or a flash memory. A volatile memory can include a random access memory (RAM), which can act as an external cache memory. As an example and not by way of limitation, RAM can be obtained in a variety of forms, such as synchronous RAM (DRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct Rambus RAM (DRRAM). The storage devices of the disclosed aspects are intended to include, but are not limited to, these and other suitable types of memory.

[0053] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any marked order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0054] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0055] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An AR application method based on Bentley software modeling, characterized in that: The method comprises the following steps: Step 1: Open the Bentley View application, use the Bentley View to open the DGN file, and publish the DGN file as an iModel file; Step 2: Use iModel.js to build a model parsing program, use Node.js as the development environment, Typescript as the development language, and install the iModel.js method library through npm; The analysis process specifically includes the following steps: Step 2.1: Get a snapshot of the model database through the openFile function of the SnapshotDb class; Step 2.2: traverse all physical objects in the model database through the withPreparedStatement function in the snapshot in step 2.1; Step 2.3: Obtain the geometry and material information of the physical object through the exportGraphics function in the snapshot in step 2.1, wherein each physical object includes one or more ExportGraphicsInfo, and each ExportGraphicsInfo includes the geometry information and material information of a mesh, wherein the geometry information includes vertices, normals, index lists, and texture coordinate information; the material information includes color, texture, and rendering mode information; Step 2.4: Obtain the attribute information of the physical object through the getAspects function of the elements attribute in the snapshot in step 2.1, wherein each physical object contains one or more ElementAspects, each ElementAspect represents a set of attributes, and traverse each attribute through forEachProperty to obtain complete attribute information; Step 3: Output the parsing result as a GLTF file and load it in the AR application.

2. The AR application method based on Bentley software modeling according to claim 1, characterized in that: The format definition of the GLTF file includes nine core parts, which specifically include scene, node, mesh, accessor, buffer view, buffer, material, texture, and image.

3. The AR application method based on Bentley software modeling according to claim 2, characterized in that: The relationships between the core parts specifically include: The physical object described in step 2.2 corresponds to the node in the GLTF file; The grid described in the step 2.3 corresponds to the mesh in the GLTF file, the geometric information of the grid is stored in the buffer of the GLTF file in binary form, and is accurately matched through the buffer view and the accessor, and the object of the material information of the grid corresponds to the material in the GLTF file, the mapping information in the material corresponds to the texture in the GLTF file, and the image data is also stored in the buffer of the GLTF file in binary form and is associated in the image of the GLTF file.

4. The AR application method based on Bentley software modeling according to claim 1, characterized in that: In the step 2.2, the physical objects in the model database are traversed using an ECSQL statement, wherein the ECSQL statement is SELECTECInstanceId FROM bis.SpatialIndex.

5. The AR application method based on Bentley software modeling according to claim 1, characterized in that: The AR application also supports OBJ and FBX format file output.

6. The AR application method based on Bentley software modeling according to claim 1, characterized in that: The loading process of the AR application includes the following steps: Step 4.1: Initialize the GLTF loader in the AR application and configure the loader parameters to support asynchronous loading; Step 4.2: Call the load function of the loader, pass in the path of the GLTF file, and start loading the model data; Step 4.3: After loading is complete, use the AR framework to render the model into the real world, specifically including setting the position, rotation, and scale of the model; the AR framework is ARCore.

7. The AR application method based on Bentley software modeling according to claim 6, characterized in that: The AR application supports real-time interaction, which specifically includes the following steps: Step 5.1: Setting a touch event listener in the AR application to detect the user's touch operation; Step 5.2: According to the touch position of the user, count the interactions with the model in the AR scene, where the interactions specifically include selection, dragging, and zooming operations; Step 5.3: Apply user interaction operations to the model and update the model status in real time; The state of the updated model also includes version control of the model data, specifically including: Step 5.3.1: Generate a new version number and record the update log every time the model data is updated; Step 5.3.2: Provide a user interface for users to view and select different versions of model data; Step 5.3.3: Load the selected version of the GLTF file in the AR application for display.

8. The AR application method based on Bentley software modeling according to claim 1, characterized in that: The step 3 also includes optimizing the performance of the AR application, which specifically includes the following steps: Step 6.1: During the model loading process, use LOD technology to dynamically adjust the model's level of detail based on the user's perspective and distance; Step 6.2: Implement a model culling mechanism to avoid rendering model parts outside the user's field of view to improve rendering efficiency; Step 6.3: Use GPU acceleration technology and Instancing technology to reduce the number of draw calls to optimize the rendering process of the model.

9. The AR application method based on Bentley software modeling according to claim 1, characterized in that: The method is applied to the design and construction scenarios of roads, bridges, and power infrastructure.

10. An AR application system based on Bentley software modeling, used to implement an AR application method based on Bentley software modeling according to any one of claims 1 to 9, characterized in that: The system comprises: Bentley View module, which is used to open DGN files and publish them as iModel files; The model parsing module is built based on iModel.js, using Node.js as the development environment and Typescript as the development language. The iModel.js method library is installed through npm. The module includes: The snapshot acquisition unit obtains a snapshot of the model database through the openFile function of the SnapshotDb class; A physical object traversal unit, which traverses all physical objects in the model database through the withPreparedStatement function in the snapshot; A geometry and material information extraction unit, which obtains geometry and material information of a physical object through the exportGraphics function in the snapshot, wherein each physical object contains one or more ExportGraphicsInfo, and each ExportGraphicsInfo contains geometry information and material information of a mesh; An attribute information acquisition unit, which acquires attribute information of a physical object through the getAspects function of the elements attribute in the snapshot, wherein each physical object contains one or more ElementAspects, and traverses each attribute through forEachProperty to acquire complete attribute information; GLTF file output module, used to output the parsing results as GLTF files and load them in AR applications; User interface module, used to display AR content and interact with users; The data storage module is used to store the parsed model data and user interaction records.

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