Convert DGN to IFC in your application
3D InterOp is a CAD interoperability SDK that lets your software read DGN files and write IFC, writing the exact geometry into a format that can also hold facets.
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 IFC
- Exact geometry → mixed-geometry format
- C++ / C# APIs
DGN to IFC at a glance
MicroStation DGN stores exact geometry; IFC can hold exact solids and facets. What ends up in the IFC file depends on what the IFC writer writes, as detailed below.
| MicroStation DGN (source) | IFC (target) | |
|---|---|---|
| Full name | MicroStation Design file | Industry Foundation Classes |
| Standard / owner | Bentley Systems | buildingSMART, ISO 16739 |
| File extensions | .dgn | .ifc, .ifczip |
| Geometry | Exact B-Rep | Exact B-Rep and tessellated geometry |
| Assemblies / structure | Yes: models and references | Yes: spatial and element 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 IFC.
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Preserved
Exact geometryExact B-Rep read from DGN is written to IFC as exact geometry.
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Preserved
Product structureThe DGN product structure is written to IFC.
Why software vendors add DGN to IFC conversion
Open BIM deliverables
Many projects specify IFC deliverables. Writing it lets your users meet those requirements from your software.
Coordination and clash detection
Coordination tools gather models from every discipline in IFC. Your users can contribute without a round trip through another tool.
Facility and asset data
Owners and operators often receive building data as IFC for asset management after handover.
Things to check before you ship
- Written IFC versions: IFC2x3 to IFC4x3 ADD2 (.ifc).
- Exact B-Rep needs IFC4 or later; IFC2x3 files only get tessellation.
- 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 an IFC (.ifc) file?
IFC is the open, vendor-neutral standard for exchanging building information models, maintained by buildingSMART and published as ISO 16739. It carries building elements with their geometry, properties and relationships.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from DGN is written to IFC.
Yes. 3D InterOp reads the DGN product structure and writes it to IFC.
Write IFC4 or later to keep exact B-Rep: IFC2x3 files only get tessellation. 3D InterOp writes IFC2x3 to IFC4x3 ADD2.
3D InterOp reads DGN V7 to V8.
3D InterOp writes IFC2x3 to IFC4x3 ADD2 (.ifc).
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 IFC?
3D InterOp is an SDK that lets your application read MicroStation DGN and write IFC alongside 30+ CAD and BIM formats.