Convert RFA to Parasolid in your application
3D InterOp is a CAD interoperability SDK that lets your software read RFA files and write Parasolid, carrying across the exact geometry the RFA file contains.
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 Revit family · Writes Parasolid
- Mixed geometry → exact geometry
- C++ / C# APIs
RFA to Parasolid at a glance
Revit family can mix exact solids and facets; Parasolid stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| Revit family (source) | Parasolid (target) | |
|---|---|---|
| Full name | Revit family | Parasolid transmit file (text X_T, binary X_B) |
| Standard / owner | Autodesk | Proprietary — Siemens |
| File extensions | .rfa | .x_t, .x_b, .xmt_txt, .xmt_bin |
| Geometry | B-Rep and mesh (read); mesh (written by 3D InterOp) | Exact B-Rep |
| Assemblies / structure | Nested families; assembly structure written by 3D InterOp | Yes (Parasolid assembly structure) |
| 3D InterOp support | Read and write | Read and write · up to Parasolid 38 |
What's preserved, what changes
Here is what your application can expect to carry across from Revit family to Parasolid.
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Preserved
Exact geometryExact B-Rep read from RFA is written to Parasolid as exact geometry.
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Changes
Faceted partsParts the RFA file stores only as facets are written as facets.
Why software vendors add RFA to Parasolid conversion
Hand models to kernel-based applications
Many CAD, CAM and CAE applications are built on the Parasolid kernel. Writing Parasolid gives them exact geometry they can load without another translation step.
Downstream modeling and analysis
An exact Parasolid B-Rep can still be edited, meshed or machined by downstream tools, which a tessellated export would not allow.
Exchange within one ecosystem
Partners whose tools share the Parasolid kernel often prefer to exchange Parasolid files directly.
Things to check before you ship
- Written Parasolid versions: Parasolid 12 to 38.0.150.
- Writing Parasolid needs a Parasolid installation: there is no Parasolid Direct writer.
- Supported RFA input: Revit 2015 to 2026.
- 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 RFA (.rfa) file?
An RFA file is a Revit family: a reusable component such as a door, a window or a piece of equipment, with its geometry, types and parameters, loaded into Revit projects.
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Target format
What is a Parasolid (X_T) file?
Parasolid is the geometric modeling kernel developed by Siemens and used by many CAD, CAM and CAE applications. Its transmit files store exact B-Rep models as text (.x_t) or binary (.x_b).
Frequently asked questions
The exact B-Rep that 3D InterOp reads from RFA is written to Parasolid; parts stored only as facets stay faceted.
Parasolid has no assembly hierarchy, so your application decides how the RFA structure is grouped or flattened before writing.
Yes. Writing Parasolid needs a Parasolid installation: there is no Parasolid Direct writer.
3D InterOp reads Revit 2015 to 2026.
3D InterOp writes Parasolid 12 to 38.0.150.
Yes. 3D InterOp reads and writes both formats, so Parasolid to RFA is supported too.
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Building software that needs to convert RFA to Parasolid?
3D InterOp is an SDK that lets your application read Revit family and write Parasolid alongside 30+ CAD and BIM formats.