Convert STP to XCGM in your application
3D InterOp is a CAD interoperability SDK that lets your software read STP files and write XCGM, 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 STEP · Writes XCGM
- Exact geometry → exact geometry
- C++ / C# APIs
STP to XCGM at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| STEP (source) | XCGM (target) | |
|---|---|---|
| Full name | Standard for the Exchange of Product model data | CGM native file |
| Standard / owner | ISO 10303 — AP203, AP214, AP242 | Dassault Systèmes / Spatial (CGM Modeler) |
| File extensions | .stp, .step | .xcgm |
| Geometry | Exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes | Yes |
| PMI | Graphical and semantic (AP242) | Semantic (read) |
| 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 STEP to XCGM.
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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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Improved
Healed geometry3D InterOp repairs and heals STEP data during translation.
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Not carried
PMI3D InterOp doesn’t write PMI to XCGM, so the PMI read from STP isn’t written. Keep STEP AP242 as an output when PMI matters.
Why software vendors add STP to XCGM conversion
Hand models to kernel-based applications
Many CAD, CAM and CAE applications are built on the XCGM kernel. Writing XCGM gives them exact geometry they can load without another translation step.
Downstream modeling and analysis
An exact XCGM 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 XCGM kernel often prefer to exchange XCGM files directly.
Things to check before you ship
- Written XCGM versions: R2012 to 2025 1.0.
- PMI and miscellaneous data aren’t written to XCGM.
- Supported STP input: AP203, AP214 and AP242.
- 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 a STEP (.stp) file?
STEP is the ISO 10303 standard for exchanging 3D product data between CAD systems. Its application protocols range from exact geometry (AP203, AP214) to full model-based definition with PMI (AP242).
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Target format
What is an XCGM (.xcgm) file?
XCGM is the native file format of the CGM geometric kernel, used by CGM Modeler and Dassault Systèmes applications. It stores exact B-Rep geometry.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
3D InterOp doesn’t write PMI to XCGM, so the PMI read from STP isn’t written. When PMI matters, offer STEP AP242 as an output.
No. PMI and miscellaneous data aren’t written to XCGM.
3D InterOp reads AP203, AP214 and AP242.
3D InterOp writes R2012 to 2025 1.0.
Yes. 3D InterOp reads and writes both formats, so XCGM to STP is supported too.
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Building software that needs to convert STP to XCGM?
3D InterOp is an SDK that lets your application read STEP and write XCGM alongside 30+ CAD and BIM formats.