Convert JT to CGR in your application
3D InterOp is a CAD interoperability SDK that lets your software read JT files and write CGR, generating the CGR 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 CGR
- Mixed geometry → triangle mesh
- C++ / C# APIs
JT to CGR at a glance
JT can mix exact solids and facets; CGR stores triangles only, so the whole model is tessellated when it is written.
| JT (source) | CGR (target) | |
|---|---|---|
| Full name | Jupiter Tessellation | CATIA Graphical Representation |
| Standard / owner | Siemens, ISO 14306 | Dassault Systèmes |
| File extensions | .jt | .cgr |
| Geometry | Tessellated and/or exact B-Rep | Tessellated geometry |
| Assemblies / structure | Yes | Single part |
| PMI | Semantic and graphical | None |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from JT to CGR.
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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.
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Changes
Assembly structureCGR has no native assembly hierarchy. Decide in your application how JT product structure is grouped or flattened before writing.
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Not carried
PMICGR has no place for PMI, so the PMI read from JT isn’t written.
Why software vendors add JT to CGR conversion
Lightweight review
CGR 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 CGR file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, CGR files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- Written CGR versions: CATIA V5 R15 to V5-6 R2026, with the CATIA V5 writer.
- 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 CGR (.cgr) file?
CGR is CATIA’s lightweight graphical representation format. It stores a tessellated version of a part for fast display in large assemblies.
Frequently asked questions
3D InterOp tessellates the geometry it reads from JT when it writes CGR. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
CGR 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.
CGR has no assembly hierarchy, so your application decides how the JT structure is grouped or flattened before writing.
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 CGR files with its CATIA V5 writer, for CATIA V5 R15 to V5-6 R2026.
No. 3D InterOp reads JT but doesn’t write it. To send data back, write a neutral format such as STEP.
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Building software that needs to convert JT to CGR?
3D InterOp is an SDK that lets your application read JT and write CGR alongside 30+ CAD and BIM formats.