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Documentation

How To Export A Model With Terrain From Revit?

This knowledge base article answers the following questions:

  • How to export a CAD model with terrain or topography from Revit?
  • Can we import such terrain models directly into SimScale from Revit?

Workflow

For city massing models with relatively flat terrains, users can decide if the topography is relevant for analysis. To export just the buildings from Revit, follow the article about “How to export a model from Revit to SimScale?”

In case of uneven topography, performing a wind analysis with the terrain model is preferred. Revit models the topography as surfaces called Toposurfaces. Although a direct export from Revit with terrain is possible, there is also a workaround to do this.

Direct export to SimScale

It is possible to directly export a terrain model from Revit as .RVT, and then upload it to SimScale.

  • Select the ‘File’ tab;
  • Save your model as a ‘Project’:
saving the revit model as project to export the terrain
Figure 1: A direct export of the terrain model as .RVT is possible when saving it as a Project.

Then name the file, and choose the location where it will be saved:

name and save the terrain file as rvt
Figure 2: Naming and saving the .RVT file at the end of the export

It is now ready to be uploaded to SimScale.

Exporting Models With Terrain From Revit using Rhino

Another workaround for exporting topographies is to export them in DXF CAD format. To export the entire project as a DXF file (along with buildings), please make them active in the current viewer. Then export it to a DXF file from ‘File —>Export —> CAD Formats —> DXF’.

saving the model in DXF form
Figure 3: Exporting a terrain model in DXF format

In the following dialog box, select the name and folder of interest, then press ‘Next’, thereby saving the model to the desired location.

dxf export from revit
Figure 4: Naming and saving the terrain at the end of the export as a DXF file

Importing DXF Files into SimScale

To import this model with terrain into SimScale, an STL file should be created out of the DXF. In this article, this is explained using Rhino.

In order to open the DXF file in Rhino, select Open —> select the DXF file from Revit —> open.

opening dxf file in rhino
Figure 5: Using Rhino to open the DXF file that was previously exported from Revit

Select the ‘Convert wide polylines to surfaces’ option and set the Mesh to ‘Automatic’ at the import:

Units

While importing the DXF file into Rhino, please make sure that the units are appropriate. For example, if the model is exported in meters from Revit, then select Meters while importing into Rhino. This might affect the topography file if set wrongly.

rhino dxf import options
Figure 6: Rhino import options

With Rhino, you can simply export the DXF file as an STL as shown in the image below.

Figure7: Finally, the terrain is converted to an STL file and is ready to be saved and imported to SimScale.

This STL file is now ready to be imported into SimScale. Just like other CAD model extensions the import process for STL files is explained in our CAD preparation and upload documentation.

To find out how to extend a terrain using Rhino click here.

Last updated: August 25th, 2021

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