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Introduction
This article will show you how to convert an AutoCAD DWG (.dwg) file to MicroStation DGN (.dgn) in FME. In addition to a basic format-to-format translation, we will modify the schema and use the DGNStyler to style the output data.
Step-by-Step Instructions
In this scenario, we will use road data, which is divided into different layers for each road type and each with a different symbology. We will transform the symbology, convert the AutoCAD attributes to MicroStation tags, and merge a few layers before writing to DGN.
Download this article's attachments, including the source data and finished workspace, to follow along.
1. Create a Blank Workspace in FME Workbench
Open FME Workbench and start a blank workspace.
2. Add an Autodesk AutoCAD DWG/DXF Reader
Click Add Reader and set the following parameters:
- Format: Autodesk AutoCAD DWG/DXF
- Dataset: <Path to tutorial download>/roads.dwg
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Parameters:
- Group Entities By: Attribute Schema
Setting the parameter to group by attribute schema allows us to visualize the layers with attribute information. Other parameters (collapsed in the screenshot) control different aspects of reading the DWG data.
Click OK twice to add the reader to the workspace.
The Select Feature Types dialog will appear. Leave all feature types checked to import all layers, and click OK.
You have successfully added a DWG reader for Roads.dwg to the workspace. The canvas should look as follows:
3. Add Bentley Microstation Design (V8) DGN Writer
Click Add Writer, and set the following:
- Format: Bentley Microstation Design (V8) DGN
- Dataset: <Path to destination>/Roads.dgn
- Level Definition: Copy from Reader
Click Parameters, and set the following:
- Write tags: Yes
- Seed File (V8 only): <Path to FME installation>/design/seed2d_ft_v8.dgn
The Write tags parameter tells FME to write tags for the features. The Seed File parameter specifies a 2D output instead of 3D. Seed files are located in your FME installation folder. For example, *\FME 2022.2\design\seed2d_ft_v8.dgn on Windows or /Library/FME/2022.2/design/seed2d_ft_v8.dgn on Mac.
Click OK on the Parameters dialog and OK again to add the writer to the workspace.
The Select Feature Type dialog will appear. Select all feature types and click OK.
You have successfully added a DGN writer to the workspace. The canvas should look as follows:
You can then connect all the reader feature types to their corresponding writer feature types:
4. Modify the Output Schema
The workspace currently creates an exact copy of the source data. We would like to modify the layers in the output file before running it.
- Drag the connections from the input feature types NonCity, Other, and Private to the output layer Other
- Connect the rest of the input feature types to their respective outputs
- Delete the unused NonCity and Private output feature types
The workspace should look as follows:
5. Add a DGNStyler Transformer
We will now style the output symbology. Add a DGNStyler and connect it before the Other output feature type. The workspace should look as follows:
Open the transformer's parameters and set the following:
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Color: Enabled
- RGB Color: choose a color or set it to lilac: 0.666667,0.666667,1
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Lines: Enabled
- Line Weight: 3
- Line Style: 2
6. Run the Workspace
Click Run Workspace. When the translation is complete, navigate to the output DGN dataset in your file system. You can inspect the output using the FME Data Inspector or a 3rd-party CAD viewer such as Bentley View.
Note how the line data in the DGN file has been written using the symbology specified in the DGNStyler, and the DWG attributes have been written as MicroStation tags. When opened in Bentley View, we can see that the Cambie Bridge in Vancouver has been styled under the 'Other' feature type, showing as a dotted line with the colour we set earlier.
Data Attribution
The data used here originates from open data made available by the City of Vancouver, British Columbia. It contains information licensed under the Open Government License - Vancouver.