Convert STP to VDA-FS in your application
3D InterOp is a CAD interoperability SDK that lets your software read STP files and write VDA-FS, 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 STEP · Writes VDA-FS
- Exact geometry → exact geometry
- C++ / C# APIs
STP 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.
| STEP (source) | VDA-FS (target) | |
|---|---|---|
| Full name | Standard for the Exchange of Product model data | VDA surface interface |
| Standard / owner | ISO 10303 — AP203, AP214, AP242 | VDA (German automotive industry) |
| File extensions | .stp, .step | .vda |
| Geometry | Exact B-Rep | Exact curves and surfaces |
| Assemblies / structure | Yes | No assembly hierarchy |
| PMI | Graphical and semantic (AP242) | 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 STEP 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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Improved
Healed geometry3D InterOp repairs and heals STEP data during translation.
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Changes
Assembly structureVDA-FS has no native assembly hierarchy. Decide in your application how STEP product structure is grouped or flattened before writing.
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Not carried
PMIVDA-FS has no PMI, so the PMI read from STP isn’t written. Keep STEP AP242 as an output when PMI matters.
Why software vendors add STP 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 STP input: AP203, AP214 and AP242.
- 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 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).
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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 STP isn’t written. When PMI matters, offer STEP AP242 as an output.
VDA-FS has no assembly hierarchy, so your application decides how the STP structure is grouped or flattened before writing.
No. The VDA-FS writer isn’t available in 3D InterOp CGM.
3D InterOp reads AP203, AP214 and AP242.
3D InterOp writes VDA-FS 2.0.
Yes. 3D InterOp reads and writes both formats, so VDA-FS to STP is supported too.
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Building software that needs to convert STP to VDA-FS?
3D InterOp is an SDK that lets your application read STEP and write VDA-FS alongside 30+ CAD and BIM formats.