Convert JT to glTF in your application
3D InterOp is a CAD interoperability SDK that lets your software read JT files and write glTF, generating the glTF 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 glTF
- Mixed geometry → triangle mesh
- C++ / C# APIs
JT to glTF at a glance
JT can mix exact solids and facets; glTF stores triangles only, so the whole model is tessellated when it is written.
| JT (source) | glTF (target) | |
|---|---|---|
| Full name | Jupiter Tessellation | GL Transmission Format |
| Standard / owner | Siemens, ISO 14306 | Khronos Group |
| File extensions | .jt | .gltf, .glb |
| Geometry | Tessellated and/or exact B-Rep | Triangle mesh |
| Assemblies / structure | Yes | Yes: scene hierarchy |
| PMI | Semantic and graphical | None |
| 3D InterOp support | Read only | Write only |
What's preserved, what changes
Here is what your application can expect to carry across from JT to glTF.
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Preserved
Product structureThe JT product structure is written to glTF.
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Preserved
PMI as wiresThe glTF writer supports wires, which lets CAD files with PMI be converted to glTF for the web.
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Improved
Compressed meshesThe glTF writer can compress meshes with Draco, available since 2026 1.0.1.
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Changes
Geometry is tessellatedThe 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.
Why software vendors add JT to glTF conversion
Lightweight review
glTF 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 glTF file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, glTF files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- Written glTF versions: glTF 2.0 (.gltf or .glb).
- The glTF 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 StudyAbout the formats
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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.
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Target format
What is a glTF (.gltf, .glb) file?
glTF is the Khronos Group’s open format for delivering 3D content on the web and in real-time applications. It stores meshes, materials and the scene in a compact .gltf or binary .glb file.
Frequently asked questions
3D InterOp tessellates the geometry it reads from JT when it writes glTF. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
The glTF writer supports wires, so PMI can be carried to glTF as visual geometry for web viewing.
Yes. 3D InterOp reads the JT product structure and writes it to glTF.
Yes. Since 3D InterOp 2026 1.0.1, the glTF writer can compress meshes with Draco. It writes glTF 2.0 as .gltf or .glb.
The glTF 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.
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Building software that needs to convert JT to glTF?
3D InterOp is an SDK that lets your application read JT and write glTF alongside 30+ CAD and BIM formats.