Convert CGR to IGES in your application
3D InterOp is a CAD interoperability SDK that lets your software read CGR files and write IGES, writing the CGR facets as faceted geometry, since CGR stores triangles rather than solids.
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 IGES
- Triangle mesh → faceted B-Rep
- C++ / C# APIs
CGR to IGES at a glance
CGR stores triangles; IGES is an exact-geometry format. The mesh is written as faceted geometry: 3D InterOp doesn’t rebuild smooth surfaces from triangles.
| CGR (source) | IGES (target) | |
|---|---|---|
| Full name | CATIA Graphical Representation | Initial Graphics Exchange Specification |
| Standard / owner | Dassault Systèmes | ANSI |
| File extensions | .cgr | .igs, .iges |
| Geometry | Tessellated geometry | Exact B-Rep and surfaces |
| Assemblies / structure | Single part | No native 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 IGES.
-
Changes
Faceted geometryCGR stores triangles, so the IGES file holds faceted bodies, not solids. 3D InterOp doesn’t rebuild exact B-Rep from a mesh.
Why software vendors add CGR to IGES conversion
Legacy CAD and CAM systems
Many established engineering tools still consume IGES first. Writing it lets your users hand data to them without leaving your application.
Supplier and partner exchange
Some suppliers and manufacturing partners still specify IGES in their exchange requirements. Your software can meet them directly.
Geometry-only workflows
When a downstream process needs exact part geometry and nothing more, IGES is a simple, widely readable target.
Things to check before you ship
- Written IGES versions: IGES 5.3.
- Supported CGR input: CATIA V5 R8 to V5-6 R2026.
- 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
-
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.
-
Target 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.
Frequently asked questions
No. CGR stores triangles, and 3D InterOp writes them to IGES as faceted geometry. It doesn’t rebuild exact B-Rep from a mesh.
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.
3D InterOp writes IGES 5.3.
Yes. 3D InterOp reads and writes both formats, so IGES to CGR is supported too.
-
Building software that needs to convert CGR to IGES?
3D InterOp is an SDK that lets your application read CGR and write IGES alongside 30+ CAD and BIM formats.