Convert ASAT to Parasolid in your application
3D InterOp is a CAD interoperability SDK that lets your software read ASAT files and write Parasolid, 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 Parasolid
- Exact geometry → exact geometry
- C++ / C# APIs
ASAT to Parasolid 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) | Parasolid (target) | |
|---|---|---|
| Full name | ACIS assembly, text (ASAT) and binary (ASAB) | Parasolid transmit file (text X_T, binary X_B) |
| Standard / owner | Spatial (3D ACIS Modeler) | Proprietary — Siemens |
| File extensions | .asat, .asab | .x_t, .x_b, .xmt_txt, .xmt_bin |
| Geometry | Exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes | Yes (Parasolid assembly structure) |
| 3D InterOp support | Read and write | Read and write · up to Parasolid 38 |
What's preserved, what changes
Here is what your application can expect to carry across from ACIS assembly to Parasolid.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
Why software vendors add ASAT to Parasolid conversion
Hand models to kernel-based applications
Many CAD, CAM and CAE applications are built on the Parasolid kernel. Writing Parasolid gives them exact geometry they can load without another translation step.
Downstream modeling and analysis
An exact Parasolid 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 Parasolid kernel often prefer to exchange Parasolid files directly.
Things to check before you ship
- Written Parasolid versions: Parasolid 12 to 38.0.150.
- Writing Parasolid needs a Parasolid installation: there is no Parasolid Direct writer.
- 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 a Parasolid (X_T) file?
Parasolid is the geometric modeling kernel developed by Siemens and used by many CAD, CAM and CAE applications. Its transmit files store exact B-Rep models as text (.x_t) or binary (.x_b).
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
Parasolid has no assembly hierarchy, so your application decides how the ASAT structure is grouped or flattened before writing.
Yes. Writing Parasolid needs a Parasolid installation: there is no Parasolid Direct writer.
3D InterOp reads ACIS R1 to 2026 1.0.
3D InterOp writes Parasolid 12 to 38.0.150.
Yes. 3D InterOp reads and writes both formats, so Parasolid to ASAT is supported too.
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Building software that needs to convert ASAT to Parasolid?
3D InterOp is an SDK that lets your application read ACIS assembly and write Parasolid alongside 30+ CAD and BIM formats.