Convert CGR to OBJ in your application
3D InterOp is a CAD interoperability SDK that lets your software read CGR files and write OBJ, carrying the mesh data across without re-tessellating it, 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 CGR · Writes OBJ
- Triangle mesh → triangle mesh
- C++ / C# APIs
CGR to OBJ at a glance
Both formats store triangles, so the facets carry over without re-tessellation. The differences are in structure, appearance and metadata.
| CGR (source) | OBJ (target) | |
|---|---|---|
| Full name | CATIA Graphical Representation | Wavefront OBJ |
| Standard / owner | Dassault Systèmes | Open format |
| File extensions | .cgr | .obj |
| Geometry | Tessellated geometry | Polygon mesh |
| Assemblies / structure | Single part | No assembly hierarchy |
| 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 CGR to OBJ.
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Preserved
Mesh dataThe CGR facets are read and written to OBJ without being re-tessellated.
Why software vendors add CGR to OBJ conversion
Lightweight review
OBJ 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 OBJ file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, OBJ files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- The OBJ writer is available through the UConnect interface only.
- Supported CGR 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 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.
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Target format
What is an OBJ (.obj) file?
OBJ is a simple, widely supported text format for polygon meshes, created by Wavefront. It describes vertices, faces and texture coordinates, with materials in a separate .mtl file.
Frequently asked questions
No re-tessellation is needed. 3D InterOp reads the CGR facets as visualization data and writes them to OBJ.
The OBJ writer is available through the 3D InterOp UConnect interface.
No. 3D InterOp reads CGR files directly, without CATIA or a CATIA license on the machine.
3D InterOp reads CATIA V5 R8 to V5-6 R2026, as visualization data.
Yes. 3D InterOp reads and writes both formats, so OBJ to CGR is supported too.
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Building software that needs to convert CGR to OBJ?
3D InterOp is an SDK that lets your application read CGR and write OBJ alongside 30+ CAD and BIM formats.