Convert IAM to CGR in your application
3D InterOp is a CAD interoperability SDK that lets your software read IAM 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 Inventor assembly · Writes CGR
- Exact geometry → triangle mesh
- C++ / C# APIs
IAM to CGR at a glance
Inventor assembly 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.
| Inventor assembly (source) | CGR (target) | |
|---|---|---|
| Full name | Autodesk Inventor Assembly | CATIA Graphical Representation |
| Standard / owner | Autodesk | Dassault Systèmes |
| File extensions | .iam | .cgr |
| Geometry | Exact B-Rep (in the referenced parts) | Tessellated geometry |
| Assemblies / structure | Yes | 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 Inventor assembly to CGR.
-
Changes
Geometry is tessellatedThe exact Inventor assembly 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.
-
Changes
Assembly structureCGR has no native assembly hierarchy. Decide in your application how Inventor assembly product structure is grouped or flattened before writing.
Why software vendors add IAM 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 IAM input: Inventor V11 to 2027.
- 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
-
Source format
What is an IAM (.iam) file?
An IAM file is an Autodesk Inventor assembly. It stores the product structure and constraints, and references the IPT part files.
-
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 IAM 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 IAM structure is grouped or flattened before writing.
3D InterOp reads Inventor V11 to 2027.
3D InterOp writes CGR files with its CATIA V5 writer, for CATIA V5 R15 to V5-6 R2026.
No. 3D InterOp reads IAM but doesn’t write it. To send data back to Inventor users, write a neutral format they can import, such as STEP.
-
Building software that needs to convert IAM to CGR?
3D InterOp is an SDK that lets your application read Inventor assembly and write CGR alongside 30+ CAD and BIM formats.