Convert STP to 3DXML in your application
3D InterOp is a CAD interoperability SDK that lets your software read STP files and write 3DXML, generating the 3DXML mesh from the geometry it reads, with tessellation settings your application controls.
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 3D XML
- Exact geometry → triangle mesh
- C++ / C# APIs
STP to 3DXML at a glance
STEP stores exact geometry; 3D XML stores triangles. The translation is a tessellation, and the settings you choose decide how close the mesh stays to the original.
| STEP (source) | 3D XML (target) | |
|---|---|---|
| Full name | Standard for the Exchange of Product model data | 3D XML |
| Standard / owner | ISO 10303 — AP203, AP214, AP242 | Dassault Systèmes |
| File extensions | .stp, .step | .3dxml |
| Geometry | Exact B-Rep | Tessellated geometry |
| Assemblies / structure | Yes | Yes |
| PMI | Graphical and semantic (AP242) | Graphical PMI |
| 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 3D XML.
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Preserved
Product structureThe STP product structure is written to 3DXML.
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Improved
Healed geometry3D InterOp repairs and heals STEP data during translation.
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Changes
Geometry is tessellatedThe exact STEP B-Rep is replaced by a triangle mesh, generated by 3D InterOp from the exact geometry it reads. Accuracy depends on the tessellation settings your application uses.
Why software vendors add STP to 3DXML conversion
Lightweight review
3D XML carries tessellated geometry that opens much faster than the full CAD model, so design reviews and digital mockups stay responsive.
Sharing outside engineering
Marketing, training and sales teams rarely have CAD software. A 3D XML file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, 3D XML files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- Written 3DXML versions: 3D XML 4.3, as static tessellation.
- Only static tessellation is written, not XML tessellation.
- Supported STP input: AP203, AP214 and AP242.
- Test tessellation settings on your heaviest parts: finer meshes mean larger 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 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 a 3D XML (.3dxml) file?
3D XML is Dassault Systèmes’ lightweight XML-based format for sharing 3D product data. 3D InterOp reads and writes its tessellated representation, with product structure and graphical PMI.
Frequently asked questions
3D InterOp tessellates the geometry it reads from STP when it writes 3DXML. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
The 3D XML writer can write graphical PMI such as views, captures and text.
Yes. 3D InterOp reads the STP product structure and writes it to 3DXML.
3D InterOp writes 3D XML 4.3 with static tessellation. XML tessellation isn’t written.
3D InterOp reads AP203, AP214 and AP242.
3D InterOp writes 3D XML 4.3, as static tessellation.
Yes. 3D InterOp reads and writes both formats, so 3DXML to STP is supported too.
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Building software that needs to convert STP to 3DXML?
3D InterOp is an SDK that lets your application read STEP and write 3D XML alongside 30+ CAD and BIM formats.