Convert RFA to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read RFA files and write CATPart, 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 CATPart
- Mixed geometry → exact geometry
- C++ / C# APIs
RFA to CATPart at a glance
Revit family can mix exact solids and facets; CATPart stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| Revit family (source) | CATPart (target) | |
|---|---|---|
| Full name | Revit family | CATIA V5 Part |
| Standard / owner | Autodesk | Dassault Systèmes |
| File extensions | .rfa | .CATPart |
| Geometry | B-Rep and mesh (read); mesh (written by 3D InterOp) | Exact B-Rep |
| Assemblies / structure | Nested families; assembly structure written by 3D InterOp | Part file (assemblies are CATProduct files) |
| PMI | None | Semantic and graphical |
| 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 Revit family to CATPart.
-
Preserved
Exact geometryExact B-Rep read from RFA is written to CATPart as exact geometry.
-
Changes
Assembly structureCATPart has no native assembly hierarchy. Decide in your application how Revit family product structure is grouped or flattened before writing.
-
Changes
Faceted partsParts the RFA file stores only as facets are written as facets.
Why software vendors add RFA to CATPart conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATPart. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATPart keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATPart directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATPart versions: CATIA V5 R15 to V5-6 R2026.
- 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
-
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.
-
Target 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.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from RFA is written to CATPart; parts stored only as facets stay faceted.
CATPart has no assembly hierarchy, so your application decides how the RFA structure is grouped or flattened before writing.
3D InterOp reads Revit 2015 to 2026.
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
Yes. 3D InterOp reads and writes both formats, so CATPart to RFA is supported too.
-
Building software that needs to convert RFA to CATPart?
3D InterOp is an SDK that lets your application read Revit family and write CATPart alongside 30+ CAD and BIM formats.