Convert 3DM to CGR in your application
3D InterOp is a CAD interoperability SDK that lets your software read 3DM files and write CGR, generating the CGR mesh from the geometry it reads, with tessellation settings your application controls.
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 Rhino · Writes CGR
- Exact geometry → triangle mesh
- C++ / C# APIs
3DM to CGR at a glance
Rhino 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.
| Rhino (source) | CGR (target) | |
|---|---|---|
| Full name | Rhinoceros 3D model | CATIA Graphical Representation |
| Standard / owner | Robert McNeel & Associates | Dassault Systèmes |
| File extensions | .3dm | .cgr |
| Geometry | Exact NURBS geometry and meshes | Tessellated geometry |
| Assemblies / structure | No assembly hierarchy | Single part |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from Rhino to CGR.
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Changes
Geometry is tessellatedThe exact Rhino 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.
Why software vendors add 3DM 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 3DM input: Rhino 2 to 8.
- 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 3DM (.3dm) file?
3DM is the native file format of Rhinoceros (Rhino), the NURBS modeler from Robert McNeel & Associates. It stores exact curves, surfaces and solids, as well as meshes.
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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 3DM when it writes CGR. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
No. 3D InterOp reads Rhino geometry, but importing mapping data isn’t supported.
3D InterOp reads Rhino 2 to 8.
3D InterOp writes CGR files with its CATIA V5 writer, for CATIA V5 R15 to V5-6 R2026.
No. 3D InterOp reads 3DM but doesn’t write it. To send data back to Rhino users, write a neutral format they can import, such as STEP.
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Building software that needs to convert 3DM to CGR?
3D InterOp is an SDK that lets your application read Rhino and write CGR alongside 30+ CAD and BIM formats.