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1. Introduction to BIM
BIM refers to Building Information Modeling (Building Information Modeling). At present, there is no official definition in China. Therefore, it is understood from foreign BIM standards that BIM is a digital expression of a construction project or the physical and functional characteristics of an implementation. It is not displayed in a two-dimensional manner. , but directly expressed in a three-dimensional way; at the same time, BIM is also a shared knowledge resource, which is the process of providing basis for all decisions in the entire life cycle of the facility from construction to demolition; at different stages of the project, different stakeholders through BIM changes and modifies information to achieve coordinated operations. Based on its own characteristics, BIM is currently more and more widely used in construction and some design fields.
2. The necessity of combining BIM and 3D GIS
2.1 BIM requires 3D GIS
For BIM, the entire life cycle of BIM from design, construction to operation and maintenance is aimed at the BIM single refined model, but it is impossible to break away from the surrounding macro-geographical environment elements and become a castle in the air. And 3D GIS has been committed to the research of the macro-geographical environment, providing various spatial query and spatial analysis functions, and in the operation and maintenance phase of BIM, 3D GIS can provide decision support for it, so BIM needs 3D GIS.
2.2 3D GIS requires BIM
For 3D GIS, BIM data is another important data source of 3D GIS, which can make 3D GIS go from macro to micro, and can realize refined management. On the other hand, the integration with BIM data makes 3D GIS move from outdoor to indoor, realizing the integrated management of indoor and outdoor.
2.3 Integration of BIM data and 3D GIS
The BIM data structure includes spatial data (model) and attribute data (parameters), in which the spatial data model includes spatial location, appearance
This is similar to the data structure of 3D GIS, and the attribute data includes design parameters, construction parameters and operation and maintenance parameters. 3D GIS covers BIM's data structure (spatial data + attribute data), BIM's data representation (3D model), and BIM data objects (BIM is for architectural objects, GIS covers a wide range, including architectural objects), and BIM functions overlap (information management, spatial analysis, etc.), so 3D GIS+BIM can generate unlimited possibilities.
3. Problems faced by the combination of the two
3.1 How to connect data
As we all know, there are many BIM software at home and abroad, and there are many corresponding BIM file formats. Some common BIM file formats are: RVT
: BIM data format used by Autodesk Revit software, including: RFA, ADSK and other formats;
CATPart : The data format of CATIA software, including: CATProduct, CATdrawing and other formats;
DGN: The data format developed by Bentley to support its Microstation series products.
For Autodesk Revit software, we provide the SuperMap Export plug-in (plug-in location: link: link:
http://pan.baidu.com/s/1qYgyxpa password: 30ry). The SuperMap Export plug-in exports the BIM model of Revit as a model dataset, and saves it under the specified data source file to complete the data export. The connection between CATIA and DGN software temporarily uses the transfer format, and the data is exported through the 3ds Max plug-in provided by us.
Revit plug-in configuration instructions:
install Revit2016;
Download the plug-in compression package, and the plug-in configuration file .bat must be placed in the same directory as Bin_x64
Run the plug-in configuration file *.bat file;
The plug-in must be used in the 3D view of Revit
Open the Revit software, the configuration is successful, as shown in the figure below:
Figure: SuperMap Export plug-in successfully configured
Note: If there is a plug-in button in the menu bar, and an exception pops up directly after starting the button, then you need to check whether Bin_x64 has been
set as a system environment variable, and make sure it is at the forefront of the path. After completing the configuration of the plug-in, the BIM model can be exported. The steps are as follows:
Open the BIM data in Revit software;
Select "Default 3D View" in the "View" tab > "Create" group > "3D View" drop-down box or in the floating box of "Project Browser" on the left side of the interface , select the 3D view;
Click the "Additional Modules" tab > "SuperMap Export" button, and the "Export Parameter Settings" dialog box will pop up, as
shown in the figure below:
Figure: BIM model "Export Parameter Settings" dialog box
There are two export modes, one is the insertion point method, the other is the projection method;
Insertion point information: select the insertion point information, you can directly set spherical coordinates or plane Coordinates
Custom projection: Select the projection method to export the model
Create or open a UDB data source;
Select the color type of the exported model. The coloring color is consistent with the effect seen in Revit; the real color is the color rendered by Revit;
Network dataset: export the pipeline data as a 3D point and line dataset, and construct a 3D network dataset through point lines.
Instancing: Check the export data by default. If you find that the position or color of the data in some datasets is disordered, uncheck the instantiation export model. At present, there are hidden dangers in the plug-in distinguishing instantiation. If you find disordered layers, it is recommended to use this family type Export separately in a non-instantiated manner;
after data export is complete, open the data source of the specified file path. All model data sets can be opened and browsed directly in the scene, but it is recommended to first generate a cache for the data set through the "BIM Generate Cache" function; generating a cache optimizes the performance of all aspects, and opening it in a cache mode will improve the browsing effect. better. Moving the cached layer with translucency to the top will ensure that the layer is displayed correctly. Through the window, you can clearly see the indoor scene.
Figure: window semi-transparent display effect Open the cache layer browser in the scene, you can intuitively see the effect of the model and the attribute information of a single primitive. Turn on the selection mode or
select the roaming mode, double-click an element object, and the property floating box of the selected object will pop up on the right side of the interface. All attribute information of the object is displayed in the floating box, as shown in the figure below:
Figure: Part of the attribute information of the selected object
3.2 How to guarantee the performance
Taking the architectural data of a building as an example, there are more than 6,600 primitive categories opened in Revit software, and each primitive contains a lot of attribute information, so we use performance optimization technology to meet the performance needs of large volume data . Three key technologies are mentioned here.
The first key technology is instantiation. This technology is suitable for situations where there are many repeated models. It can only draw the same geometric model once, reducing the pressure on hardware devices such as graphics cards.
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