Convert DGN to VDA-FS in your application
3D InterOp is a CAD interoperability SDK that lets your software read DGN files and write VDA-FS, with exact B-Rep geometry carried across and nothing tessellated.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads MicroStation DGN · Writes VDA-FS
- Exact geometry → exact geometry
- C++ / C# APIs
DGN to VDA-FS at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| MicroStation DGN (source) | VDA-FS (target) | |
|---|---|---|
| Full name | MicroStation Design file | VDA surface interface |
| Standard / owner | Bentley Systems | VDA (German automotive industry) |
| File extensions | .dgn | .vda |
| Geometry | Exact B-Rep | Exact curves and surfaces |
| Assemblies / structure | Yes: models and references | No assembly hierarchy |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from MicroStation DGN to VDA-FS.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
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Changes
Assembly structureVDA-FS has no native assembly hierarchy. Decide in your application how MicroStation DGN product structure is grouped or flattened before writing.
Why software vendors add DGN to VDA-FS conversion
Legacy CAD and CAM systems
Many established engineering tools still consume VDA-FS first. Writing it lets your users hand data to them without leaving your application.
Supplier and partner exchange
Some suppliers and manufacturing partners still specify VDA-FS in their exchange requirements. Your software can meet them directly.
Geometry-only workflows
When a downstream process needs exact part geometry and nothing more, VDA-FS is a simple, widely readable target.
Things to check before you ship
- Written VDA-FS versions: VDA-FS 2.0.
- The VDA-FS writer isn’t available in 3D InterOp CGM.
- Supported DGN input: DGN V7 to V8.
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is a DGN (.dgn) file?
DGN is the native design file format of Bentley MicroStation, widely used for infrastructure, plant and civil engineering projects. It exists in two generations, V7 and V8.
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Target format
What is a VDA-FS (.vda) file?
VDA-FS is a neutral surface-exchange format defined by the German automotive association VDA. It stores exact curves and free-form surfaces, and is still found in automotive supply chains.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
VDA-FS has no assembly hierarchy, so your application decides how the DGN structure is grouped or flattened before writing.
No. The VDA-FS writer isn’t available in 3D InterOp CGM.
3D InterOp reads DGN V7 to V8.
3D InterOp writes VDA-FS 2.0.
No. 3D InterOp reads DGN but doesn’t write it. To send data back to MicroStation users, write a neutral format they can import, such as IFC or STEP.
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Building software that needs to convert DGN to VDA-FS?
3D InterOp is an SDK that lets your application read MicroStation DGN and write VDA-FS alongside 30+ CAD and BIM formats.