What is a VDA-FS file?
VDA-FS stands for "Verband der Automobilindustrie - Flächenschnittstelle", the surface data interface of the German automotive industry association. A VDA-FS file, usually saved with the .vda extension, is a plain-text file that stores the geometry of a part as spline curves, spline surfaces, trimmed faces and points, following version 1.0 or 2.0 of the standard.
The format was created at a time when each CAD system used its own internal representation, and carmakers needed a neutral way to send body panels and tooling surfaces to their suppliers. It focuses on surface geometry for a single part: it does not describe assemblies, and it only carries a few attributes such as layers and entity names.
What does a VDA-FS file contain?
A VDA-FS file is a sequence of named elements. Each element type describes one kind of geometric or organizational data.
| Element | Content | Imported by 3D InterOp as |
| CURVE | Spline curve | B-spline curve |
| SURF | Spline surface | B-spline surface |
| FACE | Surface bounded by trimming curves | Face |
| TOP | Set of faces that belong together | Body |
| POINT | Single point | Vertex |
| PSET, MDI | Point sets and points with direction vectors | Groups (point information only for MDI) |
| GROUP | Grouping of other elements | Group |
VDA-FS vs. STEP
In automotive data exchange, VDA-FS has been replaced by STEP, first with AP214 and then AP242. The two formats differ mainly in scope.
| Feature | VDA-FS | STEP |
| Geometry | Spline curves, surfaces, faces and points | Full B-rep solids and surfaces, including analytic geometry |
| Analytic surfaces | Not supported, stored as splines | Supported natively |
| Assemblies | Not supported | Supported |
| Attributes | Limited (layers, names) | Rich attributes, colors and PMI |
| Status | Legacy German standard (DIN 66301) | Current ISO standard (ISO 10303) |
What Is VDA-FS Used For? Applications and Industry Use Cases
Today VDA-FS is mostly found in legacy data: historical archives of automotive OEMs, older body and styling surfaces, and the files exchanged by tooling and die suppliers that still work with long-lived programs. Engineers who need to reuse, modify or simulate those parts must be able to open the original surfaces without rebuilding them by hand.
For software developers, VDA-FS import is a way to make an application useful to automotive customers and suppliers who still hold this data. Because the format only carries part-level surface geometry, it is typically read into a modeling kernel, stitched into closed bodies where needed, and then used for modeling, simulation or visualization.
Challenges or Common Pitfalls
VDA-FS files often do not carry face-to-face connectivity. Faces can arrive as separate sheets, and the application has to stitch them in the modeling kernel to recover closed solids. Data accuracy matters here: when the input surfaces do not meet precisely, some geometry may be lost or need repair.
The format only knows spline geometry. When a model with planes, cylinders, offsets or sweeps is written to VDA-FS, those surfaces must be converted to splines, which makes files larger and removes the original analytic definition.
Finally, VDA-FS holds a single part and very little metadata. Assembly structure, colors and PMI are not part of the format, so projects that need them should move to STEP or another richer format.
How Spatial Helps
Our 3D InterOp SDK both imports and exports VDA-FS files with the .vda extension. Your application can bring legacy automotive surface data into CGM Modeler, 3D ACIS Modeler or Parasolid through the same API it uses for other CAD formats.
On import, 3D InterOp reads B-rep geometry, including solids, surfaces, free surfaces, free wires and free points. It maps VDA-FS curves and surfaces to B-spline geometry, carries layer and entity name attributes along with topology names, and exposes document information such as units, author, version, source system and modification date. Since VDA-FS files contain no visualization data, 3D InterOp tessellates the imported geometry automatically so it can be displayed.
On export, 3D InterOp converts analytic and procedural surfaces to splines so they can be written in VDA-FS. Check the 3D InterOp documentation for the VDA-FS versions supported in your release.