Convert JT to IGES in your application
3D InterOp is a CAD interoperability SDK that lets your software read JT files and write IGES, 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 IGES
- Mixed geometry → exact geometry
- C++ / C# APIs
JT to IGES at a glance
JT can mix exact solids and facets; IGES stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| JT (source) | IGES (target) | |
|---|---|---|
| Full name | Jupiter Tessellation | Initial Graphics Exchange Specification |
| Standard / owner | Siemens, ISO 14306 | ANSI |
| File extensions | .jt | .igs, .iges |
| Geometry | Tessellated and/or exact B-Rep | Exact B-Rep and surfaces |
| Assemblies / structure | Yes | No native assembly hierarchy |
| PMI | Semantic and graphical | None documented in 3D InterOp |
| 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 IGES.
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Preserved
Exact geometryExact B-Rep read from JT is written to IGES as exact geometry.
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Changes
Assembly structureIGES 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.
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Not carried
PMIIGES has no PMI, so the PMI read from JT isn’t written. Keep STEP AP242 as an output when PMI matters.
Why software vendors add JT to IGES conversion
Legacy CAD and CAM systems
Many established engineering tools still consume IGES first. Writing it lets your users hand data to them without leaving your application.
Supplier and partner exchange
Some suppliers and manufacturing partners still specify IGES in their exchange requirements. Your software can meet them directly.
Geometry-only workflows
When a downstream process needs exact part geometry and nothing more, IGES is a simple, widely readable target.
Things to check before you ship
- Written IGES versions: IGES 5.3.
- 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 an IGES (.igs) file?
IGES is one of the earliest neutral CAD formats, an ANSI standard for exchanging 2D and 3D geometry. It stores exact curves, surfaces and solids, but not the product structure and manufacturing data STEP can carry.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from JT is written to IGES; parts stored only as facets stay faceted.
IGES has no PMI, so the PMI read from JT isn’t written. When PMI matters, offer STEP AP242 as an output.
IGES 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 IGES 5.3.
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 IGES?
3D InterOp is an SDK that lets your application read JT and write IGES alongside 30+ CAD and BIM formats.