Convert CATPart to CGR in your application
3D InterOp is a CAD interoperability SDK that lets your software read CATPart files and write CGR, generating the CGR mesh from the geometry it reads, with tessellation settings your application controls, without a CATIA license.
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 CATPart · Writes CGR
- Exact geometry → triangle mesh
- C++ / C# APIs
CATPart to CGR at a glance
CATPart stores exact geometry; CGR stores triangles. The translation is a tessellation, and the settings you choose decide how close the mesh stays to the original.
| CATPart (source) | CGR (target) | |
|---|---|---|
| Full name | CATIA V5 Part | CATIA Graphical Representation |
| Standard / owner | Dassault Systèmes | Dassault Systèmes |
| File extensions | .CATPart | .cgr |
| Geometry | Exact B-Rep | Tessellated geometry |
| Assemblies / structure | Part file (assemblies are CATProduct files) | Single part |
| PMI | Semantic and graphical | None |
| 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 CATPart to CGR.
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Changes
Geometry is tessellatedThe exact CATPart 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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Not carried
PMICGR has no place for PMI, so the PMI read from CATPart isn’t written.
Why software vendors add CATPart 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 CATPart input: CATIA V5 R8 to V5-6 R2026.
- 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 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.
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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 CATPart 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 CATPart isn’t written. Your application can still access it after import, or offer STEP AP242 as an output.
No. 3D InterOp reads CATPart files directly, without CATIA or a CATIA license on the machine.
3D InterOp reads CATIA V5 R8 to V5-6 R2026.
3D InterOp writes CGR files with its CATIA V5 writer, for CATIA V5 R15 to V5-6 R2026.
Yes. 3D InterOp reads and writes both formats, so CGR to CATPart is supported too.
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Building software that needs to convert CATPart to CGR?
3D InterOp is an SDK that lets your application read CATPart and write CGR alongside 30+ CAD and BIM formats.