Convert DGN to CATProduct in your application
3D InterOp is a CAD interoperability SDK that lets your software read DGN files and write CATProduct, 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 CATProduct
- Exact geometry → exact geometry
- C++ / C# APIs
DGN to CATProduct 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) | CATProduct (target) | |
|---|---|---|
| Full name | MicroStation Design file | CATIA V5 Product (assembly) |
| Standard / owner | Bentley Systems | Dassault Systèmes |
| File extensions | .dgn | .CATProduct |
| Geometry | Exact B-Rep | Exact B-Rep (in the referenced parts) |
| Assemblies / structure | Yes: models and references | Yes |
| PMI | Not imported by 3D InterOp | Semantic and graphical |
| 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 CATProduct.
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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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Preserved
Product structureThe DGN product structure is written to CATProduct.
Why software vendors add DGN to CATProduct conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATProduct. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATProduct keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATProduct directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATProduct versions: CATIA V5 R15 to V5-6 R2026.
- A CATProduct written by 3D InterOp can’t reference files in other formats.
- 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 CATProduct (.CATProduct) file?
A CATProduct file is a CATIA V5 assembly. It defines the product structure and positions, and references the CATPart files that hold the geometry.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
Yes. 3D InterOp reads the DGN product structure and writes it to CATProduct.
No. A CATProduct written by 3D InterOp can’t reference files in other formats.
3D InterOp reads DGN V7 to V8.
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
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 CATProduct?
3D InterOp is an SDK that lets your application read MicroStation DGN and write CATProduct alongside 30+ CAD and BIM formats.