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For software developers · 3D InterOp SDK

Convert JT to FBX in your application

3D InterOp is a CAD interoperability SDK that lets your software read JT files and write FBX, generating the FBX 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 JT · Writes FBX
  • Mixed geometry → triangle mesh
  • C++ / C# APIs
assembly.jtJT 10.x · lightweight assembly
Your application
3D InterOp SDK
JT readerTessellationFBX writer
scene.fbxFBX · mesh scene

JT to FBX at a glance

JT can mix exact solids and facets; FBX stores triangles only, so the whole model is tessellated when it is written.

JT (source)FBX (target)
Full nameJupiter TessellationFilmbox
Standard / ownerSiemens, ISO 14306Autodesk
File extensions.jt.fbx
GeometryTessellated and/or exact B-RepTriangle mesh
Assemblies / structureYesYes: scene hierarchy
PMISemantic and graphicalNone
3D InterOp supportRead onlyRead and write

What's preserved, what changes

Here is what your application can expect to carry across from JT to FBX.

  • Changes
    Geometry is tessellated
    The exact JT 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.
  • Not carried
    PMI
    FBX has no place for PMI, so the PMI read from JT isn’t written.

Why software vendors add JT to FBX conversion

Lightweight review

FBX 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 FBX file gives them the shape in a format their tools can open.

Easier handling of large assemblies

Without exact surfaces and feature data, FBX files are easier to transfer and display, even for large assemblies.

Things to check before you ship

  • Written FBX versions: FBX 7.7.0.
  • Points and wires aren’t written to FBX.
  • The FBX writer is available through the UConnect interface only.
  • Supported JT input: JT 8.x to 10.3 and 10.5 to 10.11.
  • 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 Study

About the formats

  • Source format

    What is a JT (.jt) file?

    JT is Siemens’ lightweight format for visualizing and sharing 3D product data, published as ISO 14306. A JT file can hold tessellated levels of detail, exact B-Rep, product structure and PMI.

  • Target format

    What is an FBX (.fbx) file?

    FBX is Autodesk’s format for exchanging 3D scenes between content-creation, game and real-time tools. It stores meshes, materials and the scene hierarchy.

Frequently asked questions

3D InterOp tessellates the geometry it reads from JT when it writes FBX. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.

FBX has no place for PMI, so the PMI read from JT isn’t written. Your application can still access it after import, or offer STEP AP242 as an output.

No. The FBX writer writes meshes; points and wires from the source aren’t written.

The FBX writer is available through the 3D InterOp UConnect interface.

Yes. 3D InterOp imports several levels of detail and the visual materials of JT files.

3D InterOp reads JT 8.x to 10.3 and 10.5 to 10.11.

3D InterOp writes FBX 7.7.0.

  • Building software that needs to convert JT to FBX?

    3D InterOp is an SDK that lets your application read JT and write FBX alongside 30+ CAD and BIM formats.