Convert CATPart to VDA-FS in your application
3D InterOp is a CAD interoperability SDK that lets your software read CATPart files and write VDA-FS, 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 CATPart · Writes VDA-FS
- Exact geometry → exact geometry
- C++ / C# APIs
CATPart to VDA-FS at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| CATPart (source) | VDA-FS (target) | |
|---|---|---|
| Full name | CATIA V5 Part | VDA surface interface |
| Standard / owner | Dassault Systèmes | VDA (German automotive industry) |
| File extensions | .CATPart | .vda |
| Geometry | Exact B-Rep | Exact curves and surfaces |
| Assemblies / structure | Part file (assemblies are CATProduct files) | No assembly hierarchy |
| PMI | Semantic and graphical | None |
| 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 CATPart to VDA-FS.
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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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Not carried
PMIVDA-FS has no PMI, so the PMI read from CATPart isn’t written. Keep STEP AP242 as an output when PMI matters.
Why software vendors add CATPart to VDA-FS conversion
Legacy CAD and CAM systems
Many established engineering tools still consume VDA-FS first. Writing it lets your users hand data to them without leaving your application.
Supplier and partner exchange
Some suppliers and manufacturing partners still specify VDA-FS in their exchange requirements. Your software can meet them directly.
Geometry-only workflows
When a downstream process needs exact part geometry and nothing more, VDA-FS is a simple, widely readable target.
Things to check before you ship
- Written VDA-FS versions: VDA-FS 2.0.
- The VDA-FS writer isn’t available in 3D InterOp CGM.
- Supported CATPart input: CATIA V5 R8 to V5-6 R2026.
- 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 CATPart (.CATPart) file?
A CATPart file is a CATIA V5 part: one component with its exact 3D geometry, features and, often, PMI. Assemblies of parts are stored in CATProduct files.
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Target format
What is a VDA-FS (.vda) file?
VDA-FS is a neutral surface-exchange format defined by the German automotive association VDA. It stores exact curves and free-form surfaces, and is still found in automotive supply chains.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
VDA-FS has no PMI, so the PMI read from CATPart isn’t written. When PMI matters, offer STEP AP242 as an output.
No. The VDA-FS writer isn’t available in 3D InterOp CGM.
No. 3D InterOp reads CATPart files directly, without CATIA or a CATIA license on the machine.
3D InterOp reads CATIA V5 R8 to V5-6 R2026.
3D InterOp writes VDA-FS 2.0.
Yes. 3D InterOp reads and writes both formats, so VDA-FS to CATPart is supported too.
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Building software that needs to convert CATPart to VDA-FS?
3D InterOp is an SDK that lets your application read CATPart and write VDA-FS alongside 30+ CAD and BIM formats.