Convert STL to CATIA V4 in your application
3D InterOp is a CAD interoperability SDK that lets your software read STL files and write CATIA V4, writing the STL facets as faceted geometry, since STL stores triangles rather than solids.
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 STL · Writes CATIA V4
- Triangle mesh → faceted B-Rep
- C++ / C# APIs
STL to CATIA V4 at a glance
STL stores triangles; CATIA V4 is an exact-geometry format. The mesh is written as faceted geometry: 3D InterOp doesn’t rebuild smooth surfaces from triangles.
| STL (source) | CATIA V4 (target) | |
|---|---|---|
| Full name | Stereolithography | CATIA Version 4 |
| Standard / owner | Open format | Dassault Systèmes |
| File extensions | .stl | .model, .exp, .session |
| Geometry | Triangle mesh | Exact B-Rep |
| Assemblies / structure | No | Yes (written as parts only) |
| 3D InterOp support | Read and write | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from STL to CATIA V4.
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Changes
Faceted geometrySTL stores triangles, so the CATIA V4 file holds faceted bodies, not solids. 3D InterOp doesn’t rebuild exact B-Rep from a mesh.
Why software vendors add STL to CATIA V4 conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATIA V4. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATIA V4 keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATIA V4 directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATIA V4 versions: CATIA 4.1.9 to 4.2.4 (.model).
- The CATIA V4 writer isn’t available in 3D InterOp CGM.
- Supported STL input: any STL version.
- 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 an STL file?
STL describes a 3D surface as a set of triangles, with no units, materials or assembly structure. Its simplicity makes it the usual input for 3D printing.
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Target format
What is a CATIA V4 (.model) file?
CATIA V4 is the legacy generation of Dassault Systèmes’ CATIA, whose models are mostly stored in .model files. Many aerospace and automotive archives still hold CATIA V4 data.
Frequently asked questions
No. STL stores triangles, and 3D InterOp writes them to CATIA V4 as faceted geometry. It doesn’t rebuild exact B-Rep from a mesh.
No. The CATIA V4 writer isn’t available in 3D InterOp CGM.
STL files store no units, so the 3D InterOp STL reader assumes millimeters. Agree on the unit with the application that wrote the file.
3D InterOp reads any STL version, as visualization data.
3D InterOp writes CATIA 4.1.9 to 4.2.4 (.model).
Yes. 3D InterOp reads and writes both formats, so CATIA V4 to STL is supported too.
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Building software that needs to convert STL to CATIA V4?
3D InterOp is an SDK that lets your application read STL and write CATIA V4 alongside 30+ CAD and BIM formats.