Convert CATIA V4 to STL in your application
3D InterOp is a CAD interoperability SDK that lets your software read CATIA V4 files and write STL, generating the STL mesh from the geometry it reads, with tessellation settings your application controls, without a CATIA license.
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 CATIA V4 · Writes STL
- Exact geometry → triangle mesh
- C++ / C# APIs
CATIA V4 to STL at a glance
CATIA V4 stores exact geometry; STL stores triangles. The translation is a tessellation, and the settings you choose decide how close the mesh stays to the original.
| CATIA V4 (source) | STL (target) | |
|---|---|---|
| Full name | CATIA Version 4 | Stereolithography |
| Standard / owner | Dassault Systèmes | Open format |
| File extensions | .model, .exp, .session | .stl |
| Geometry | Exact B-Rep | Triangle mesh |
| Assemblies / structure | Yes (written as parts only) | No |
| 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 CATIA V4 to STL.
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Changes
Geometry is tessellatedThe exact CATIA V4 B-Rep is replaced by a triangle mesh, generated by 3D InterOp from the exact geometry it reads. Accuracy depends on the tessellation settings your application uses.
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Changes
Assembly structureSTL has no native assembly hierarchy. Decide in your application how CATIA V4 product structure is grouped or flattened before writing.
Why software vendors add CATIA V4 to STL conversion
Additive manufacturing
STL is still the input most slicers and print services expect. Writing it lets your users send parts to print directly.
Mesh-based processing
Inspection, scan comparison and mesh-editing tools work on triangles. A mesh output gives them a model they can open anywhere.
Lightweight sharing
A mesh is simpler than the native CAD file and needs no CAD system to open.
Things to check before you ship
- Supported CATIA V4 input: CATIA 4.1.9 to 4.2.4 (.model, .exp, .session).
- Test tessellation settings on your heaviest parts: finer meshes mean larger files.
- 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 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.
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Target 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.
Frequently asked questions
3D InterOp tessellates the geometry it reads from CATIA V4 when it writes STL. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
STL has no assembly hierarchy, so your application decides how the CATIA V4 structure is grouped or flattened before writing.
No. STL stores triangles only, with no units, colors or textures. Agree on the unit with the application that reads the file; the 3D InterOp STL reader assumes millimeters.
No. 3D InterOp reads CATIA V4 files directly, without CATIA or a CATIA license on the machine.
3D InterOp reads CATIA 4.1.9 to 4.2.4 (.model, .exp, .session).
Yes. 3D InterOp reads and writes both formats, so STL to CATIA V4 is supported too.
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Building software that needs to convert CATIA V4 to STL?
3D InterOp is an SDK that lets your application read CATIA V4 and write STL alongside 30+ CAD and BIM formats.