Convert CATIA V4 to STP in your application
3D InterOp is a CAD interoperability SDK that lets your software read CATIA V4 files and write STP, with exact B-Rep geometry carried across and nothing tessellated, 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 STEP
- Exact geometry → exact geometry
- C++ / C# APIs
CATIA V4 to STP at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| CATIA V4 (source) | STEP (target) | |
|---|---|---|
| Full name | CATIA Version 4 | Standard for the Exchange of Product model data |
| Standard / owner | Dassault Systèmes | ISO 10303 — AP203, AP214, AP242 |
| File extensions | .model, .exp, .session | .stp, .step |
| Geometry | Exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes (written as parts only) | Yes |
| PMI | None in the format | Graphical and semantic (AP242) |
| 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 STEP.
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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 CATIA V4 product structure is written to STP.
Why software vendors add CATIA V4 to STP conversion
Supplier and OEM exchange
STEP is the ISO standard most supply chains specify for exchanging 3D models. Writing it lets your users send data to partners on any CAD system.
Model-based definition
STEP AP242 can carry semantic PMI next to exact geometry, so your users can share models together with their manufacturing data.
Long-term archiving
As an ISO standard independent of any CAD vendor, STEP is widely used to archive product data.
Things to check before you ship
- Written STP versions: AP203, AP214 or AP242 (.stp, .step or .stpx).
- Supported CATIA V4 input: CATIA 4.1.9 to 4.2.4 (.model, .exp, .session).
- 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 a STEP (.stp) file?
STEP is the ISO 10303 standard for exchanging 3D product data between CAD systems. Its application protocols range from exact geometry (AP203, AP214) to full model-based definition with PMI (AP242).
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 CATIA V4 product structure and writes it to STP.
The STEP writer supports AP203, AP214 and AP242, with AP214 as the default. Your application sets the version at export; semantic PMI is written to AP242 only.
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 STP to CATIA V4 is supported too.
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Building software that needs to convert CATIA V4 to STP?
3D InterOp is an SDK that lets your application read CATIA V4 and write STEP alongside 30+ CAD and BIM formats.