Convert IGES to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read IGES files and write CATPart, with exact B-Rep geometry carried across and nothing tessellated.
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 IGES · Writes CATPart
- Exact geometry → exact geometry
- C++ / C# APIs
IGES to CATPart at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| IGES (source) | CATPart (target) | |
|---|---|---|
| Full name | Initial Graphics Exchange Specification | CATIA V5 Part |
| Standard / owner | ANSI | Dassault Systèmes |
| File extensions | .igs, .iges | .CATPart |
| Geometry | Exact B-Rep and surfaces | Exact B-Rep |
| Assemblies / structure | No native assembly hierarchy | Part file (assemblies are CATProduct files) |
| PMI | None documented in 3D InterOp | Semantic and graphical |
| 3D InterOp support | Read and write | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from IGES to CATPart.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
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Improved
Healed geometry3D InterOp heals IGES data automatically on import.
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Improved
Analytic shapesShapes the IGES file stores as splines are restored to their exact analytic form.
Why software vendors add IGES 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 IGES input: IGES files up to version 5.3.
- 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 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.
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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
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
Yes. Healing runs automatically on IGES import, and shapes stored as splines are restored to their exact analytic form.
3D InterOp reads IGES files up to version 5.3.
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
Yes. 3D InterOp reads and writes both formats, so CATPart to IGES is supported too.
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Building software that needs to convert IGES to CATPart?
3D InterOp is an SDK that lets your application read IGES and write CATPart alongside 30+ CAD and BIM formats.