Convert OBJ to SAT

Applications such as AutoCAD, mechanical CAD systems, and ACIS-based engineering tools may require a SAT body instead of an OBJ polygon mesh. Conversion is therefore needed when a scanned or visual model must be opened with CAD solid tools or exchanged as an ACIS file.

What the OBJ format is

OBJ is a text-based polygon-mesh format used by Blender, Autodesk Maya, 3ds Max, Cinema 4D, MeshLab, scanners, and 3D-printing workflows. An .obj file can contain vertices, polygon faces, normals, texture coordinates, and references to material and texture files such as .mtl and image maps.

OBJ normally describes a visual mesh, not a watertight CAD solid. It does not preserve parametric features, design history, tolerances, analytic surfaces, or a standardized unit declaration. Keep referenced .mtl and texture files with the OBJ when importing, although those appearance assets do not transfer to SAT.

What the SAT format is

SAT is Spatial's ASCII exchange format for the ACIS geometric modeling kernel. It can represent analytic and spline surfaces, trimmed faces, shells, and solid ACIS bodies. CAD applications use it for geometric exchange, solid validation, Boolean operations, and downstream editing; compatible applications include AutoCAD, Inventor, Solid Edge, and other systems using ACIS technology.

SAT can contain genuine CAD surfaces rather than display-only polygon data, but conversion cannot recreate design intent or infer exact planes, cylinders, fillets, and smooth surfaces that were absent from the mesh. A literal conversion may produce faceted planar faces instead.

Convert with CAD Exchanger

1. Install a CAD Exchanger edition whose current format matrix lists both OBJ import and ACIS SAT export. Mesh-to-B-Rep functions and export formats can vary by edition and release.
2. Open the file with File → Open. Keep the OBJ, its .mtl file, and referenced textures in the same folder during import.
3. Check the model's scale. Because OBJ has no dependable standardized unit field, select the intended source unit and apply a scale correction before creating the CAD body.
4. Run the application's mesh-to-B-Rep or mesh-conversion command. A closed, consistently oriented mesh may become a solid; an open, non-manifold, self-intersecting, or damaged mesh may remain a shell or fail conversion.
5. Use geometry-repair or validation tools to fix holes, duplicate faces, inverted normals, non-manifold edges, and self-intersections. Confirm that the resulting body is closed.
6. Choose File → Export, select ACIS or SAT, select a compatible SAT version if the software offers that option, and save the result as model.sat.

Convert with Rhino

1. Import the OBJ with File → Import and verify the import unit and scale.
2. Repair the mesh before conversion. Rhino's Check command can identify invalid objects; use mesh-repair tools to address holes, bad normals, duplicate elements, and non-manifold topology.
3. Run MeshToNurb to create NURBS faces from the mesh. This usually creates one NURBS face for each mesh polygon.
4. Use Join to assemble the faces. Run ShowEdges to locate naked edges and use Cap only where planar openings can be closed reliably.
5. Run What and confirm that the result is a closed polysurface or solid. Select it and use File → Export Selected, then choose ACIS SAT.

Online conversion and alternative software

For nonconfidential files, CAD Exchanger's online service can be considered only when its current conversion matrix explicitly lists .obj input and .sat output. Uploading a file does not guarantee mesh-to-solid reconstruction: many browser converters only repackage or translate polygon formats and cannot produce a valid ACIS body. CrossManager and other dedicated desktop translators are alternatives when their current support matrix confirms both formats and the required mesh-to-B-Rep workflow.

Use desktop software for proprietary, large, or damaged models because it provides unit control, mesh repair, validation, and inspection before export. Do not upload confidential engineering or scan data to an online service without checking its retention and privacy terms.

Quality and compatibility limits

Mesh-to-NURBS conversion can create one surface per polygon. A dense scan may therefore produce thousands or millions of faces, a very large SAT file, slow loading, and difficult downstream editing. For mechanical parts, remodel major planes, cylinders, cones, fillets, and holes in a CAD system instead of converting every triangle literally.

The source mesh should be closed, manifold, free of self-intersections, and consistently oriented. An open mesh can be exported as surfaces or a shell but is not a valid solid for many Boolean and mass-property operations. SAT does not preserve OBJ materials, UV coordinates, textures, animation, cameras, or polygon appearance; it transfers geometric bodies.

ACIS SAT compatibility depends on the receiving application's supported ACIS version and the entities written by the exporter. If the recipient rejects the file, export an older SAT version when available or obtain the target application's required ACIS release and entity limits.