Convert ASAT to IGES in your application
3D InterOp is a CAD interoperability SDK that lets your software read ASAT files and write IGES, with exact B-Rep geometry carried across and nothing tessellated.
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 ACIS assembly · Writes IGES
- Exact geometry → exact geometry
- C++ / C# APIs
ASAT to IGES at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| ACIS assembly (source) | IGES (target) | |
|---|---|---|
| Full name | ACIS assembly, text (ASAT) and binary (ASAB) | Initial Graphics Exchange Specification |
| Standard / owner | Spatial (3D ACIS Modeler) | ANSI |
| File extensions | .asat, .asab | .igs, .iges |
| Geometry | Exact B-Rep | Exact B-Rep and surfaces |
| Assemblies / structure | Yes | 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 ACIS assembly to IGES.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
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Changes
Assembly structureIGES has no native assembly hierarchy. Decide in your application how ACIS assembly product structure is grouped or flattened before writing.
Why software vendors add ASAT 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 ASAT input: ACIS R1 to 2026 1.0.
- 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 ASAT (.asat) file?
ASAT and ASAB are the assembly versions of the ACIS save file, in text and binary form. They store the product structure of models built on Spatial’s 3D ACIS Modeler kernel.
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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
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
IGES has no assembly hierarchy, so your application decides how the ASAT structure is grouped or flattened before writing.
3D InterOp reads ACIS R1 to 2026 1.0.
3D InterOp writes IGES 5.3.
Yes. 3D InterOp reads and writes both formats, so IGES to ASAT is supported too.
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Building software that needs to convert ASAT to IGES?
3D InterOp is an SDK that lets your application read ACIS assembly and write IGES alongside 30+ CAD and BIM formats.