Convert IFC to ASAT in your application
3D InterOp is a CAD interoperability SDK that lets your software read IFC files and write ASAT, carrying across the exact geometry the IFC file contains.
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 ACIS assembly
- Mixed geometry → exact geometry
- C++ / C# APIs
IFC to ASAT at a glance
IFC can mix exact solids and facets; ACIS assembly stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| IFC (source) | ACIS assembly (target) | |
|---|---|---|
| Full name | Industry Foundation Classes | ACIS assembly, text (ASAT) and binary (ASAB) |
| Standard / owner | buildingSMART, ISO 16739 | Spatial (3D ACIS Modeler) |
| File extensions | .ifc, .ifczip | .asat, .asab |
| Geometry | Exact B-Rep and tessellated geometry | Exact B-Rep |
| Assemblies / structure | Yes: spatial and element hierarchy | Yes |
| 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 ACIS assembly.
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Preserved
Exact geometryExact B-Rep read from IFC is written to ASAT as exact geometry.
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Preserved
Product structureThe IFC product structure is written to ASAT.
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Changes
Faceted partsParts the IFC file stores only as facets are written as facets.
Why software vendors add IFC to ASAT conversion
Hand models to kernel-based applications
Many CAD, CAM and CAE applications are built on the ACIS assembly kernel. Writing ACIS assembly gives them exact geometry they can load without another translation step.
Downstream modeling and analysis
An exact ACIS assembly B-Rep can still be edited, meshed or machined by downstream tools, which a tessellated export would not allow.
Exchange within one ecosystem
Partners whose tools share the ACIS assembly kernel often prefer to exchange ACIS assembly files directly.
Things to check before you ship
- Written ASAT versions: ACIS R18 to 2026 1.0.
- Supported IFC input: IFC2x3 to IFC4x3 ADD2, from .ifc and .ifczip 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 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.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from IFC is written to ASAT; parts stored only as facets stay faceted.
Yes. 3D InterOp reads the IFC product structure and writes it to ASAT.
An ACIS assembly (ASAT/ASAB) doesn’t support layers or colors at instance level, suppressed or hidden instances, or units at instance level.
3D InterOp reads IFC2x3 to IFC4x3 ADD2, from .ifc and .ifczip files.
3D InterOp writes ACIS R18 to 2026 1.0.
Yes. 3D InterOp reads and writes both formats, so ASAT to IFC is supported too.
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Building software that needs to convert IFC to ASAT?
3D InterOp is an SDK that lets your application read IFC and write ACIS assembly alongside 30+ CAD and BIM formats.