Convert JT to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read JT files and write CATPart, carrying across the exact geometry the JT 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 JT · Writes CATPart
- Mixed geometry → exact geometry
- C++ / C# APIs
JT to CATPart at a glance
JT 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.
| JT (source) | CATPart (target) | |
|---|---|---|
| Full name | Jupiter Tessellation | CATIA V5 Part |
| Standard / owner | Siemens, ISO 14306 | Dassault Systèmes |
| File extensions | .jt | .CATPart |
| Geometry | Tessellated and/or exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes | Part file (assemblies are CATProduct files) |
| PMI | Semantic and graphical | Semantic and graphical |
| 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 CATPart.
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Preserved
Exact geometryExact B-Rep read from JT is written to CATPart as exact geometry.
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Changes
Assembly structureCATPart has no native assembly hierarchy. Decide in your application how JT product structure is grouped or flattened before writing.
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Changes
Faceted partsParts the JT file stores only as facets are written as facets.
Why software vendors add JT 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 JT input: JT 8.x to 10.3 and 10.5 to 10.11.
- 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 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 JT is written to CATPart; parts stored only as facets stay faceted.
CATPart 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 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 CATPart?
3D InterOp is an SDK that lets your application read JT and write CATPart alongside 30+ CAD and BIM formats.