BIM model shell extraction modeling method and system

Abstract

The invention provides a BIM shell extraction modeling method and system, and the method comprises the steps: analyzing a BIM in an IFC format into a structured fine model, reserving geometric, semantic and material information, carrying out the coding and simplification of each building component, and generating a simplified query model for shell extraction. Creating two cameras with consistent parameters in a three-dimensional scene, wherein the main camera is used for rendering a fine model; the auxiliary camera renders the simplified model in the background. And through the view transformation matrix, the viewpoint positions of the main camera and the auxiliary camera are kept synchronous. The auxiliary camera retrieves visible external building components through a rendering-to-texture technology, and remaps query results into the viewing angle of the main camera, so that the components are highlighted in a visual environment. According to the method, BIM shell components are selected in a real-time interactive visualization mode, the accuracy and efficiency of complex BIM shell extraction are improved, and visual query viewpoints do not need to be additionally arranged.

Description

Technical Field

[0001] The present invention relates to the field of building information technology, and in particular to a BIM model shell extraction modeling method and system. Background Art

[0002] As an important data source for building / structure modeling in digital twin cities, Building Information Modeling (BIM) has the characteristics of high geometric accuracy and rich semantic and attribute information. It is widely used in urban environment simulation, map navigation, fire emergency evacuation, virtual reality and other fields.

[0003] When facing large-scale applications at the city level, directly using BIM models expressed at the microscale will consume a lot of computing overhead and data transmission bandwidth during visualization and data transmission, reducing the efficiency of digital twin city system visualization. Shell extraction is one of the main methods for lightweight BIM. By classifying the building components of the BIM model into outdoor and indoor parts, only outdoor building components are displayed when the viewpoint is outdoors to reduce the amount of data processing and improve the efficiency of scene visualization. However, the existing shell extraction methods calculate the viewpoint position of the visibility query on the bounding sphere / bounding box of the BIM model. Due to the occlusion of building components and the limitation of query resolution, these methods have serious component missing when extracting external components, affecting the visualization effect of the digital twin city system.

[0004] The prior art uses a fixed viewpoint to extract the external triangular surface of BIM, such as patent CN201910406575.6. First, each triangle of the BIM model is assigned a unique color; then, by calculating the external bounding box of the BIM model, the 6 faces of the bounding box are selected to calculate the camera viewpoint position, and the color-coded BIM model is output as multiple texture images using orthogonal projection; finally, the set of triangles outside the BIM model is retained through texture image decoding as the shell of the three-dimensional BIM model. Although this technology can extract the BIM model shell, it has the following disadvantages: 1. Automated shell extraction can be achieved through bounding box calculation of limited query viewpoints, but it is limited to simple BIM models. For complex BIM models with component occlusion, a large amount of data will be missing; 2. The triangle-by-triangle color coding of the entire BIM model loses the inherent semantics and attribute information of the BIM model.

[0005] Therefore, an effective BIM shell extraction method is urgently needed. Summary of the invention

[0006] The present invention provides a BIM model shell extraction modeling method and system, which are used to solve the defects existing in the prior art in extracting BIM shell information.

[0007] In a first aspect, the present invention provides a BIM model shell extraction modeling method, comprising: Obtain BIM entity model constructed from building data; Parsing, simplifying and encoding the BIM entity model to obtain a coding model; Determine a dual-camera system, and use the dual-camera system to construct, transform and synchronize the encoding model of the dual-camera model to obtain a synchronization model of the dual-camera system; The external building components of the synchronous model are extracted and remapped to obtain a BIM shell model.

[0008] According to a BIM model shell extraction modeling method provided by the present invention, the BIM entity model is parsed, simplified and encoded to obtain an encoded model, including: Parsing the industrial foundation class IFC model of the BIM entity model, obtaining IFC geometric information and IFC semantic information of each building component entity, saving the IFC geometric information and the IFC semantic information as a Geode node, storing the semantic type of the building component in the name attribute of the Geode node, adding the Geode node to the OSG Group node, and obtaining the BIM entity model; Copy the OSG Group node, recursively query the Geode node name, obtain the IfcWindow node and the IfcDoor node, calculate the directed bounding box simplified door and window model and replace the corresponding nodes to obtain the BIM simplified model; The Geode nodes under the two OSG Group nodes are encoded in sequence starting from 1, and the ID value of the Geode node of the BIM simplified model is converted into an RGBA color vector to obtain a coding model.

[0009] According to a BIM model shell extraction modeling method provided by the present invention, a dual-camera system is determined, and the dual-camera system is used to construct, transform and synchronize the dual-camera model of the coding model to obtain a synchronization model of the dual-camera system, including: Build a dual-camera system consisting of a main camera and an auxiliary camera; Calculating an initial view transformation matrix, a perspective projection matrix, and a viewport transformation matrix using the bounding sphere of the BIM entity model; The view transformation matrix is ​​modified by controlling quaternion rotation, translation and scaling through the mouse and keyboard, and the main camera and the auxiliary camera are updated.

[0010] According to a BIM model shell extraction modeling method provided by the present invention, the rotation operation includes: Determine the camera's position in world coordinates , determine the coordinates of the target point in the world coordinate system as the coordinates of the model center of mass , the camera's upward vector is , to the right is ; Step 1.1, 2D coordinates on the screen when the left mouse button is pressed and depth value , get the position in the world coordinate system : (1) Step 1.2, get the next 2D coordinate and depth value by moving the mouse, and use formula 1 to get the updated position of the world coordinate system ; Step 1.3, calculate from the vector arrive The quaternion rotation matrix , update the camera's position and orientation: (2) Step 1.4: Execute steps 1.2 and 1.3 each time you move the mouse until the left mouse button is released.

[0011] According to a BIM model shell extraction modeling method provided by the present invention, the translation operation includes: Step 2.1, 2D coordinates on the screen when the right mouse button is pressed and depth value , using formula (1) to transform into the position in the world coordinate system ; Step 2.2, get the next 2D coordinate and depth value by moving the mouse, and use formula (1) to get the updated position of the world coordinate system ; Step 2.3, calculate the vector In the camera coordinate axis and Projection in direction: (3) Step 2.4, update the position of the camera and the observation target point: (4) Step 2.5: Execute steps 2.3 and 2.4 each time you move the mouse until the right button of the mouse is released.

[0012] According to a BIM model shell extraction modeling method provided by the present invention, the scaling operation includes: Determine the scaling factor Update the camera position: (5) Listen to keyboard events or mouse wheel events, and use positive and / or negative scaling factors to implement scene zoom control.

[0013] According to a BIM model shell extraction modeling method provided by the present invention, the external building components of the synchronous model are extracted and remapped to obtain a BIM shell model, including: Bind vertex colors to the Geode nodes of each building component in the synchronization model, where the color value is an encoded RGBA color vector; Copy the vertex arrays, color arrays, and triangle index data in all building component Geode nodes to the same Geode node, where the same Geode node is a query node; Add a real BIM entity model to the main camera for screen visualization, add the query node to the auxiliary camera, and use the render-to-texture RTT technology to output the visibility image at each viewpoint; Parsing the RGBA color value of each pixel in the visibility image in the callback function of the auxiliary camera, converting the RGBA color value into a building component ID, and determining that the building component ID is highlighted in the main camera; All the highlighted building component Geode nodes in the BIM entity model are exported to form the BIM shell model.

[0014] In a second aspect, the present invention further provides a BIM model shell extraction modeling system, comprising: An acquisition module, used for acquiring a BIM entity model constructed by building data; A parsing module, used for parsing, simplifying and encoding the BIM entity model to obtain a coded model; A dual-camera system synchronization module, used to determine a dual-camera system, and use the dual-camera system to construct, transform and synchronize the encoding model of the dual-camera model to obtain a synchronization model of the dual-camera system; The extraction module is used to extract and remap the external building components of the simplified model to obtain a BIM shell model.

[0015] In a third aspect, the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the BIM model shell extraction and modeling method as described above is implemented.

[0016] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described BIM model shell extraction and modeling methods.

[0017] The BIM model shell extraction modeling method and system provided by the present invention can improve the accuracy and efficiency of complex BIM model shell extraction by realizing the selection of BIM shell components in a real-time interactive visualization manner, without the need to additionally arrange viewpoints for visualization queries, and can achieve significant shell extraction effects in complex BIM models with severe occlusion of building components. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is one of the flow diagrams of the BIM model shell extraction modeling method provided by the present invention; Figure 2 This is the second flow chart of the BIM model shell extraction modeling method provided by the present invention; Figure 3 It is a structural schematic diagram of the BIM model shell extraction modeling system provided by the present invention; Figure 4 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In view of the deficiencies in the prior art, the present invention provides a visual interactive method for annotating outdoor building components in a BIM model, thereby reducing the impact caused by occlusion of building components and insufficient visual query resolution.

[0022] Figure 1 FIG. 1 is one of the flow charts of the BIM model shell extraction modeling method provided by an embodiment of the present invention, such as Figure 1 As shown, including: Step 100: Obtain a BIM entity model constructed by building data; Step 200: parsing, simplifying and encoding the BIM entity model to obtain a coded model; Step 300: determining a dual-camera system, and using the dual-camera system to construct, transform and synchronize the encoding model of the dual-camera model to obtain a synchronization model of the dual-camera system; Step 400: extracting and remapping external building components from the synchronization model to obtain a BIM shell model.

[0023] Specifically, the present invention aims to solve the problems of accuracy and computational efficiency in the process of extracting shells from complex BIM models, such as Figure 2 shown.

[0024] First, the BIM model in IFC format is parsed into a structured fine model, retaining the geometry, semantics and material information, and each building component is encoded and simplified to generate a simplified query model for shell extraction. Then, two cameras with consistent parameters are created in the 3D scene: the main camera and the auxiliary camera. The main camera is used to render the fine model for visual display on the screen; the auxiliary camera renders the simplified model in the background and is responsible for querying the external building components. The viewpoint positions of the main camera and the auxiliary camera are synchronized through the view transformation matrix. Finally, the auxiliary camera retrieves the visible external building components through the render-to-texture technology and remaps the query results to the perspective of the main camera so that these components are highlighted in the visualization environment.

[0025] The process of the present invention provides an intuitive interactive environment, where users can quickly find the unselected parts due to component occlusion, improving the accuracy of complex BIM model shell extraction. At the same time, the query process of the simplified model is accelerated by GPU, which improves the visualization efficiency of the scene and effectively reduces the extraction errors caused by gaps in building components.

[0026] Based on the above embodiment, step 200 is to parse, simplify and encode the IFC model.

[0027] Parse the IFC format file of the BIM model, obtain the IFC geometric information and IFC semantic information of each building component entity, save it as a Geode node and add it to the OSG Group node; Duplicate the Group node, recursively search for IfcWindow and IfcDoor nodes, calculate their directed bounding boxes to simplify the door and window model, and replace the corresponding Geode nodes; In order to identify each building component, the Geode nodes of the building component are encoded in sequence starting from 1. The encoding here is because each building component corresponds to an ID value, and the ID value is converted into an RGBA color vector to facilitate subsequent GPU processing.

[0028] Based on the above embodiment, step 300 includes: First, the initial view transformation matrix, perspective projection matrix and viewport transformation matrix are calculated using the bounding sphere of the BIM entity model, and two camera objects, the main camera and the auxiliary camera, are created. Modify the view transformation matrix and update the main and auxiliary cameras by controlling quaternion rotation, translation and scaling through the mouse and keyboard.

[0029] Specifically, the position of the camera in the world coordinate system is known , the coordinates of the observation target point in the world coordinate system are the coordinates of the model center of mass , the camera's upward vector is , to the right is .

[0030] (1) Rotation operation: Step 1.1, 2D coordinates on the screen when the left mouse button is pressed and depth value , get the position in the world coordinate system : (1) Step 1.2, get the next 2D coordinate and depth value by moving the mouse, and use formula 1 to get the updated position of the world coordinate system ; Step 1.3, calculate from the vector arrive The quaternion rotation matrix , update the camera's position and orientation: (2) Step 1.4: Execute steps 1.2 and 1.3 each time you move the mouse until the left mouse button is released.

[0031] (2) Translation operation: Step 2.1, 2D coordinates on the screen when the right mouse button is pressed and depth value , using formula (1) to transform into the position in the world coordinate system ; Step 2.2, get the next 2D coordinate and depth value by moving the mouse, and use formula (1) to get the updated position of the world coordinate system ; Step 2.3, calculate the vector In the camera coordinate axis and Projection in direction: (3) Step 2.4, update the position of the camera and the observation target point: (4) Step 2.5: Execute steps 2.3 and 2.4 each time you move the mouse until the right button of the mouse is released.

[0032] (3) Zoom operation Determine the scaling factor Update the camera position: (5) Listen to keyboard events or mouse wheel events, and use positive and / or negative scaling factors to implement scene zoom control.

[0033] Based on the above embodiment, step 400 includes: Bind vertex colors to the Geode nodes of each building component in the BIM simplified model, and the color value is the encoded RGBA color vector; Copy the vertex arrays, color arrays, and triangle index data in all building component Geode nodes to the same Geode node, which is called a query node. Since only one drawing command is needed to send it to the GPU for rendering, the efficiency of visual query is improved; Add a real BIM entity model to the main camera for visual display on the screen. Add a query node to the auxiliary camera and use RTT technology to output visibility images at each viewpoint; In the callback function of the auxiliary camera, parse the RGBA color value of each pixel in the visibility image, convert the color value into the ID of the building component, and notify the component ID to highlight it in the main camera; Finally, all the highlighted building component Geode nodes are exported, which is the extracted BIM shell model.

[0034] The real-time interactive BIM model shell extraction method proposed by the present invention for building component coding can provide an efficient interactive extraction method and is widely used in multiple scenarios of digital twin cities with CIM as the digital baseboard.

[0035] The BIM model shell extraction and modeling system provided by the present invention is described below. The BIM model shell extraction and modeling system described below and the BIM model shell extraction and modeling method described above can be referenced to each other.

[0036] Figure 3 is a structural diagram of a BIM model shell extraction modeling system provided by an embodiment of the present invention, such as Figure 3 As shown, it includes: an acquisition module 31, a parsing module 32, a dual-camera system synchronization module 33 and an extraction module 34, wherein: The acquisition module 31 is used to acquire the BIM entity model constructed by building data; the parsing module 32 is used to parse, simplify and encode the BIM entity model to obtain the encoded model; the dual-camera system synchronization module 33 is used to determine the dual-camera system, and use the dual-camera system to construct, transform and synchronize the dual-camera model of the encoded model to obtain the synchronized model of the dual-camera system; the extraction module 34 is used to extract and remap the external building components of the synchronized model to obtain the BIM shell model.

[0037] Figure 4 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 4 As shown, the electronic device may include: a processor 410, a communication interface 420, a memory 430 and a communication bus 440, wherein the processor 410, the communication interface 420 and the memory 430 communicate with each other through the communication bus 440. The processor 410 may call the logic instructions in the memory 430 to execute the BIM model shell extraction modeling method, which includes: obtaining a BIM entity model constructed by building data; parsing, simplifying and encoding the BIM entity model to obtain a coded model; determining a dual-camera system, using the dual-camera system to construct, transform and synchronize the coded model of the dual-camera system, and obtaining a synchronized model of the dual-camera system; extracting and remapping external building components from the synchronized model to obtain a BIM shell model.

[0038] In addition, the logic instructions in the above-mentioned memory 430 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0039] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the BIM model shell extraction and modeling method provided by the above-mentioned methods. The method includes: obtaining a BIM entity model constructed by building data; parsing, simplifying and encoding the BIM entity model to obtain a coded model; determining a dual-camera system, and using the dual-camera system to construct, transform and synchronize a dual-camera model of the coded model to obtain a synchronized model of the dual-camera system; extracting and remapping external building components of the synchronized model to obtain a BIM shell model.

[0040] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0041] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A BIM model shell extraction modeling method, characterized in that: include: Obtain the building information BIM entity model constructed by building data; Parsing, simplifying and encoding the BIM entity model to obtain a coding model; Determine a dual-camera system, and use the dual-camera system to construct, transform and synchronize the encoding model of the dual-camera model to obtain a synchronization model of the dual-camera system; The external building components of the synchronous model are extracted and remapped to obtain a BIM shell model.

2. The BIM model shell extraction modeling method according to claim 1, characterized in that: The BIM entity model is parsed, simplified and encoded to obtain an encoding model, including: Parsing the industrial foundation class IFC model of the BIM entity model, obtaining IFC geometric information and IFC semantic information of each building component entity, saving the IFC geometric information and the IFC semantic information as a Geode node, storing the semantic type of the building component in the name attribute of the Geode node, and adding the Geode node to the OSG Group node; Copy the OSG Group node, recursively query the Geode node name, obtain the IfcWindow node and the IfcDoor node, calculate the directed bounding box simplified door and window model and replace the corresponding nodes to obtain the BIM simplified model; The Geode nodes under the two OSG Group nodes are encoded in sequence starting from 1, and the ID values ​​of the Geode nodes of the BIM simplified model are converted into RGBA color vectors to obtain the encoding model.

3. The BIM model shell extraction modeling method according to claim 1, characterized in that: Determining a dual-camera system, and using the dual-camera system to construct, transform, and synchronize the encoding model of the dual-camera model to obtain a synchronization model of the dual-camera system, including: Build a dual-camera system consisting of a main camera and an auxiliary camera; Calculating an initial view transformation matrix, a perspective projection matrix, and a viewport transformation matrix using the bounding sphere of the BIM entity model; The view transformation matrix is ​​modified by controlling quaternion rotation, translation and scaling through the mouse and keyboard, and the main camera and the auxiliary camera are updated.

4. The BIM model shell extraction modeling method according to claim 3 is characterized in that: The rotation operations include: Determine the camera's position in world coordinates , determine the coordinates of the target point in the world coordinate system as the coordinates of the model center of mass , the camera's upward vector is , to the right is ; Step 1.1, 2D coordinates on the screen when the left mouse button is pressed and depth value , get the position in the world coordinate system : （1） Step 1.2, get the next 2D coordinate and depth value by moving the mouse, and use formula 1 to get the updated position of the world coordinate system ; Step 1.3, calculate from the vector arrive The quaternion rotation matrix , update the camera's position and orientation: （2） Step 1.4: Execute steps 1.2 and 1.3 each time you move the mouse until the left mouse button is released.

5. The BIM model shell extraction modeling method according to claim 4 is characterized in that: The translation operations include: Step 2.1, 2D coordinates on the screen when the right mouse button is pressed and depth value , using formula (1) to transform into the position in the world coordinate system ; Step 2.2, get the next 2D coordinate and depth value by moving the mouse, and use formula (1) to get the updated position of the world coordinate system ; Step 2.3, calculate the vector In the camera coordinate axis and Projection in direction: （3） Step 2.4, update the position of the camera and the observation target point: （4） Step 2.5: Execute steps 2.3 and 2.4 each time you move the mouse until the right button of the mouse is released.

6. The BIM model shell extraction modeling method according to claim 5, characterized in that: Scaling operations include: Determine the scaling factor Update the camera position: （5） Listen to keyboard events or mouse wheel events, and use positive and / or negative scaling factors to implement scene zoom control.

7. The BIM model shell extraction modeling method according to claim 1, characterized in that: The external building components of the synchronous model are extracted and remapped to obtain a BIM shell model, including: Bind vertex colors to the Geode nodes of each building component in the synchronization model, where the color value is an encoded RGBA color vector; Copy the vertex arrays, color arrays, and triangle index data in all building component Geode nodes to the same Geode node, where the same Geode node is a query node; Add a real BIM entity model to the main camera for screen visualization, add the query node to the auxiliary camera, and use the render-to-texture RTT technology to output the visibility image at each viewpoint; Parsing the RGBA color value of each pixel in the visibility image in the callback function of the auxiliary camera, converting the RGBA color value into a building component ID, and determining that the building component ID is highlighted in the main camera; All the highlighted building component Geode nodes in the BIM entity model are exported to form the BIM shell model.

8. A BIM model shell extraction modeling system, characterized in that: include: An acquisition module, used for acquiring a BIM entity model constructed by building data; A parsing module, used for parsing, simplifying and encoding the BIM entity model to obtain a coded model; A dual-camera system synchronization module, used to determine a dual-camera system, and use the dual-camera system to construct, transform and synchronize a dual-camera model for the coding model to obtain a synchronization model of the dual-camera system; The extraction module is used to extract and remap external building components of the synchronization model to obtain a BIM shell model.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the BIM model shell extraction and modeling method as described in any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the BIM model shell extraction and modeling method as described in any one of claims 1 to 7 is implemented.

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