Convert STL to Parasolid in your application
3D InterOp is a CAD interoperability SDK that lets your software read STL files and write Parasolid, writing the STL facets as faceted geometry, since STL 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 STL · Writes Parasolid
- Triangle mesh → faceted B-Rep
- C++ / C# APIs
STL to Parasolid at a glance
STL stores triangles; Parasolid is an exact-geometry format. The mesh is written as faceted geometry: 3D InterOp doesn’t rebuild smooth surfaces from triangles.
| STL (source) | Parasolid (target) | |
|---|---|---|
| Full name | Stereolithography | Parasolid transmit file (text X_T, binary X_B) |
| Standard / owner | Open format | Proprietary — Siemens |
| File extensions | .stl | .x_t, .x_b, .xmt_txt, .xmt_bin |
| Geometry | Triangle mesh | Exact B-Rep |
| Assemblies / structure | No | 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 STL to Parasolid.
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Changes
Faceted geometrySTL stores triangles, so the Parasolid file holds faceted bodies, not solids. 3D InterOp doesn’t rebuild exact B-Rep from a mesh.
Why software vendors add STL 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 STL input: any STL version.
- 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 STL file?
STL describes a 3D surface as a set of triangles, with no units, materials or assembly structure. Its simplicity makes it the usual input for 3D printing.
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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
No. STL stores triangles, and 3D InterOp writes them to Parasolid as faceted geometry. It doesn’t rebuild exact B-Rep from a mesh.
Yes. Writing Parasolid needs a Parasolid installation: there is no Parasolid Direct writer.
STL files store no units, so the 3D InterOp STL reader assumes millimeters. Agree on the unit with the application that wrote the file.
3D InterOp reads any STL version, as visualization data.
3D InterOp writes Parasolid 12 to 38.0.150.
Yes. 3D InterOp reads and writes both formats, so Parasolid to STL is supported too.
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Building software that needs to convert STL to Parasolid?
3D InterOp is an SDK that lets your application read STL and write Parasolid alongside 30+ CAD and BIM formats.