Convert SLDPRT to OBJ in your application
3D InterOp is a CAD interoperability SDK that lets your software read SLDPRT files and write OBJ, generating the OBJ 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 SOLIDWORKS part · Writes OBJ
- Exact geometry → triangle mesh
- C++ / C# APIs
SLDPRT to OBJ at a glance
SOLIDWORKS part stores exact geometry; OBJ stores triangles. The translation is a tessellation, and the settings you choose decide how close the mesh stays to the original.
| SOLIDWORKS part (source) | OBJ (target) | |
|---|---|---|
| Full name | SOLIDWORKS Part | Wavefront OBJ |
| Standard / owner | Dassault Systèmes SOLIDWORKS | Open format |
| File extensions | .sldprt | .obj |
| Geometry | Exact B-Rep | Polygon mesh |
| Assemblies / structure | Part file (assemblies are SLDASM files) | No assembly hierarchy |
| PMI | Semantic (DimXpert) and graphical, SOLIDWORKS 2014 and later | None |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from SOLIDWORKS part to OBJ.
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Changes
Geometry is tessellatedThe exact SOLIDWORKS part 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.
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Not carried
PMIOBJ has no place for PMI, so the PMI read from SLDPRT isn’t written.
Why software vendors add SLDPRT to OBJ conversion
Lightweight review
OBJ 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 OBJ file gives them the shape in a format their tools can open.
Easier handling of large assemblies
Without exact surfaces and feature data, OBJ files are easier to transfer and display, even for large assemblies.
Things to check before you ship
- The OBJ writer is available through the UConnect interface only.
- Supported SLDPRT input: SOLIDWORKS 98 to 2026.
- 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 an SLDPRT (.sldprt) file?
An SLDPRT file is a SOLIDWORKS part: a single component with its exact 3D geometry, feature tree and properties. SOLIDWORKS is built on the Parasolid kernel.
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Target format
What is an OBJ (.obj) file?
OBJ is a simple, widely supported text format for polygon meshes, created by Wavefront. It describes vertices, faces and texture coordinates, with materials in a separate .mtl file.
Frequently asked questions
3D InterOp tessellates the geometry it reads from SLDPRT when it writes OBJ. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
OBJ has no place for PMI, so the PMI read from SLDPRT isn’t written. Your application can still access it after import, or offer STEP AP242 as an output.
The OBJ writer is available through the 3D InterOp UConnect interface.
Yes. If your application uses Parasolid, a Parasolid-based SOLIDWORKS reader is available.
Semantic PMI from SOLIDWORKS 2014 to 2026, and graphical PMI from SOLIDWORKS 2014 onwards.
3D InterOp reads SOLIDWORKS 98 to 2026.
No. 3D InterOp reads SLDPRT but doesn’t write it. To send data back to SOLIDWORKS users, write a neutral format they can import, such as STEP.
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Building software that needs to convert SLDPRT to OBJ?
3D InterOp is an SDK that lets your application read SOLIDWORKS part and write OBJ alongside 30+ CAD and BIM formats.