Convert SAT to OBJ in your application
3D InterOp is a CAD interoperability SDK that lets your software read SAT 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 ACIS · Writes OBJ
- Exact geometry → triangle mesh
- C++ / C# APIs
SAT to OBJ at a glance
ACIS 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.
| ACIS (source) | OBJ (target) | |
|---|---|---|
| Full name | ACIS model file (text SAT, binary SAB) | Wavefront OBJ |
| Standard / owner | Proprietary — Spatial (Dassault Systèmes) | Open format |
| File extensions | .sat, .sab | .obj |
| Geometry | Exact B-Rep | Polygon mesh |
| Assemblies / structure | Parts in SAT/SAB, assemblies in ASAT/ASAB | No assembly hierarchy |
| 3D InterOp support | Read and write · ACIS R18 to 2026 1.0 | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from ACIS to OBJ.
-
Changes
Geometry is tessellatedThe exact ACIS 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.
-
Changes
Assembly structureOBJ has no native assembly hierarchy. Decide in your application how ACIS product structure is grouped or flattened before writing.
Why software vendors add SAT 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 SAT input: ACIS R1 to 2026 1.0.
- 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
-
Source format
What is an ACIS SAT file?
SAT is the native file format of 3D ACIS Modeler, Spatial's geometric modeling kernel used in CAD, CAM and CAE applications. It stores exact B-Rep models as text (.sat) or binary (.sab); ACIS assemblies use the .asat and .asab extensions.
-
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 SAT when it writes OBJ. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
The OBJ writer is available through the 3D InterOp UConnect interface.
Yes. 3D InterOp reads both ACIS text (SAT) and binary (SAB) files.
3D InterOp reads ACIS R1 to 2026 1.0.
Yes. 3D InterOp reads and writes both formats, so OBJ to SAT is supported too.
-
Building software that needs to convert SAT to OBJ?
3D InterOp is an SDK that lets your application read ACIS and write OBJ alongside 30+ CAD and BIM formats.