Convert DWG to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read DWG files and write CATPart, carrying across the exact geometry the DWG file contains.
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 DWG · Writes CATPart
- Mixed geometry → exact geometry
- C++ / C# APIs
DWG to CATPart at a glance
DWG can mix exact solids and facets; CATPart stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| DWG (source) | CATPart (target) | |
|---|---|---|
| Full name | AutoCAD Drawing | CATIA V5 Part |
| Standard / owner | Autodesk | Dassault Systèmes |
| File extensions | .dwg | .CATPart |
| Geometry | 2D drawings and 3D data | Exact B-Rep |
| Assemblies / structure | Blocks and layers | Part file (assemblies are CATProduct files) |
| PMI | None | Semantic and graphical |
| 3D InterOp support | Read; write drawings only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from DWG to CATPart.
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Preserved
Exact geometryExact B-Rep read from DWG is written to CATPart as exact geometry.
Why software vendors add DWG to CATPart conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATPart. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATPart keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATPart directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATPart versions: CATIA V5 R15 to V5-6 R2026.
- Supported DWG input: DXF/DWG 2.5 to 2027.
- A DWG file that only contains 2D drawings has no 3D geometry to write.
- 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 DWG (.dwg) file?
DWG is the native file format of Autodesk AutoCAD, used for 2D drawings and 3D models. It is one of the most widespread formats for technical drawings.
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Target format
What is a CATPart (.CATPart) file?
A CATPart file is a CATIA V5 part: one component with its exact 3D geometry, features and, often, PMI. Assemblies of parts are stored in CATProduct files.
Frequently asked questions
The exact B-Rep that 3D InterOp reads from DWG is written to CATPart; parts stored only as facets stay faceted.
Then there is no 3D geometry to write to CATPart: 3D InterOp needs 3D content in the DWG file for this conversion.
Both the 2D content (drawing sheets) and the 3D data stored in the file.
No. 3D InterOp writes drawing sheets to DXF and DWG, but 3D export to these formats isn’t supported. To send 3D data back to AutoCAD users, write a neutral 3D format such as STEP.
3D InterOp reads DXF/DWG 2.5 to 2027.
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
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Building software that needs to convert DWG to CATPart?
3D InterOp is an SDK that lets your application read DWG and write CATPart alongside 30+ CAD and BIM formats.