Convert IFC to CGR in your application
3D InterOp is a CAD interoperability SDK that lets your software read IFC 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 IFC · Writes CGR
- Mixed geometry → triangle mesh
- C++ / C# APIs
IFC to CGR at a glance
IFC can mix exact solids and facets; CGR stores triangles only, so the whole model is tessellated when it is written.
| IFC (source) | CGR (target) | |
|---|---|---|
| Full name | Industry Foundation Classes | CATIA Graphical Representation |
| Standard / owner | buildingSMART, ISO 16739 | Dassault Systèmes |
| File extensions | .ifc, .ifczip | .cgr |
| Geometry | Exact B-Rep and tessellated geometry | Tessellated geometry |
| Assemblies / structure | Yes: spatial and element hierarchy | Single part |
| 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 IFC to CGR.
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Changes
Geometry is tessellatedThe exact IFC 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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Changes
Assembly structureCGR has no native assembly hierarchy. Decide in your application how IFC product structure is grouped or flattened before writing.
Why software vendors add IFC 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 IFC input: IFC2x3 to IFC4x3 ADD2, from .ifc and .ifczip files.
- 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 an IFC (.ifc) file?
IFC is the open, vendor-neutral standard for exchanging building information models, maintained by buildingSMART and published as ISO 16739. It carries building elements with their geometry, properties and relationships.
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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 IFC when it writes CGR. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
CGR has no assembly hierarchy, so your application decides how the IFC structure is grouped or flattened before writing.
3D InterOp reads IFC2x3 to IFC4x3 ADD2, from .ifc and .ifczip files.
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 IFC is supported too.
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Building software that needs to convert IFC to CGR?
3D InterOp is an SDK that lets your application read IFC and write CGR alongside 30+ CAD and BIM formats.