Convert ASAT to VDA-FS in your application
3D InterOp is a CAD interoperability SDK that lets your software read ASAT 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 ACIS assembly · Writes VDA-FS
- Exact geometry → exact geometry
- C++ / C# APIs
ASAT 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.
| ACIS assembly (source) | VDA-FS (target) | |
|---|---|---|
| Full name | ACIS assembly, text (ASAT) and binary (ASAB) | VDA surface interface |
| Standard / owner | Spatial (3D ACIS Modeler) | VDA (German automotive industry) |
| File extensions | .asat, .asab | .vda |
| Geometry | Exact B-Rep | Exact curves and surfaces |
| Assemblies / structure | Yes | No assembly hierarchy |
| 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 ACIS assembly 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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Changes
Assembly structureVDA-FS has no native assembly hierarchy. Decide in your application how ACIS assembly product structure is grouped or flattened before writing.
Why software vendors add ASAT 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 ASAT input: ACIS R1 to 2026 1.0.
- 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 ASAT (.asat) file?
ASAT and ASAB are the assembly versions of the ACIS save file, in text and binary form. They store the product structure of models built on Spatial’s 3D ACIS Modeler kernel.
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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 assembly hierarchy, so your application decides how the ASAT structure is grouped or flattened before writing.
No. The VDA-FS writer isn’t available in 3D InterOp CGM.
3D InterOp reads ACIS R1 to 2026 1.0.
3D InterOp writes VDA-FS 2.0.
Yes. 3D InterOp reads and writes both formats, so VDA-FS to ASAT is supported too.
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Building software that needs to convert ASAT to VDA-FS?
3D InterOp is an SDK that lets your application read ACIS assembly and write VDA-FS alongside 30+ CAD and BIM formats.