Convert RFA to OBJ in your application
3D InterOp is a CAD interoperability SDK that lets your software read RFA files and write OBJ, generating the OBJ mesh from the geometry it reads, with tessellation settings your application controls.
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 OBJ
- Mixed geometry → triangle mesh
- C++ / C# APIs
RFA to OBJ at a glance
Revit family can mix exact solids and facets; OBJ stores triangles only, so the whole model is tessellated when it is written.
| Revit family (source) | OBJ (target) | |
|---|---|---|
| Full name | Revit family | Wavefront OBJ |
| Standard / owner | Autodesk | Open format |
| File extensions | .rfa | .obj |
| Geometry | B-Rep and mesh (read); mesh (written by 3D InterOp) | Polygon mesh |
| Assemblies / structure | Nested families; assembly structure written by 3D InterOp | 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 Revit family to OBJ.
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Changes
Geometry is tessellatedThe exact Revit family B-Rep is replaced by a triangle mesh, generated by 3D InterOp from the exact geometry it reads. Accuracy depends on the tessellation settings your application uses.
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Changes
Assembly structureOBJ has no native assembly hierarchy. Decide in your application how Revit family product structure is grouped or flattened before writing.
Why software vendors add RFA to OBJ conversion
Lightweight review
OBJ carries tessellated geometry that opens much faster than the full CAD model, so design reviews and digital mockups stay responsive.
Sharing outside engineering
Marketing, training and sales teams rarely have CAD software. A OBJ file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, OBJ files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- The OBJ writer is available through the UConnect interface only.
- Supported RFA input: Revit 2015 to 2026.
- Test tessellation settings on your heaviest parts: finer meshes mean larger files.
- 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 an OBJ (.obj) file?
OBJ is a simple, widely supported text format for polygon meshes, created by Wavefront. It describes vertices, faces and texture coordinates, with materials in a separate .mtl file.
Frequently asked questions
3D InterOp tessellates the geometry it reads from RFA when it writes OBJ. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
OBJ has no assembly hierarchy, so your application decides how the RFA structure is grouped or flattened before writing.
The OBJ writer is available through the 3D InterOp UConnect interface.
3D InterOp reads Revit 2015 to 2026.
Yes. 3D InterOp reads and writes both formats, so OBJ to RFA is supported too.
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Building software that needs to convert RFA to OBJ?
3D InterOp is an SDK that lets your application read Revit family and write OBJ alongside 30+ CAD and BIM formats.