Convert DGN to XCGM in your application
3D InterOp is a CAD interoperability SDK that lets your software read DGN files and write XCGM, 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 XCGM
- Exact geometry → exact geometry
- C++ / C# APIs
DGN to XCGM 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) | XCGM (target) | |
|---|---|---|
| Full name | MicroStation Design file | CGM native file |
| Standard / owner | Bentley Systems | Dassault Systèmes / Spatial (CGM Modeler) |
| File extensions | .dgn | .xcgm |
| Geometry | Exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes: models and references | Yes |
| PMI | Not imported by 3D InterOp | Semantic (read) |
| 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 XCGM.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
Why software vendors add DGN to XCGM conversion
Hand models to kernel-based applications
Many CAD, CAM and CAE applications are built on the XCGM kernel. Writing XCGM gives them exact geometry they can load without another translation step.
Downstream modeling and analysis
An exact XCGM B-Rep can still be edited, meshed or machined by downstream tools, which a tessellated export would not allow.
Exchange within one ecosystem
Partners whose tools share the XCGM kernel often prefer to exchange XCGM files directly.
Things to check before you ship
- Written XCGM versions: R2012 to 2025 1.0.
- PMI and miscellaneous data aren’t written to XCGM.
- 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 XCGM (.xcgm) file?
XCGM is the native file format of the CGM geometric kernel, used by CGM Modeler and Dassault Systèmes applications. It stores exact B-Rep geometry.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
No. PMI and miscellaneous data aren’t written to XCGM.
3D InterOp reads DGN V7 to V8.
3D InterOp writes R2012 to 2025 1.0.
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 XCGM?
3D InterOp is an SDK that lets your application read MicroStation DGN and write XCGM alongside 30+ CAD and BIM formats.