Are there UV coordinates in the OBJ?

No. OFF has no texture coordinates to carry across, and none are invented, so the .obj has no vt lines. Unwrap it in a 3D application if you need to texture it.

Why does the .obj come without a .mtl file?

Because an .mtl is only written for a material that has a name, and the material the OFF reader attaches is unnamed. The geometry still carries one material internally, but there is no name to write an .mtl entry against, so the download is a bare .obj.

Is this conversion lossy for geometry?

No. Vertex positions and faces carry through, with polygons triangulated and normals computed from them. Nothing is dropped from the geometry itself.

OFF to OBJ Converter

Convert a bare OFF geometry file to Wavefront OBJ with normals computed from the source triangles. Runs in your browser.

Drag & drop your OFF file here

or click to browse

Supported Formats

.glb.gltf.obj.fbx.stl.ply.3mf.off.zip

Format Information

Source Format

OFF.off

OFF (Object File Format)

OFF is a minimal, human-readable geometry format from the Geomview project: a header line, a count line, then a list of vertex positions and a list of polygon vertex lists. There is deliberately nothing else in the specification.

What it carries: Vertex positions and face index lists, written out as triangles. No normals, no colours, no UVs, no materials, no textures and no animation.

Open a OFF file in the viewer

Target Format

OBJ.obj

OBJ (Wavefront)

The Wavefront OBJ format is a plain-text mesh description that has been the default interchange format for computer graphics since the 1990s. Geometry lives in the .obj file; colour and texture references live in a companion .mtl file.

What it carries: Vertex positions, normals, texture coordinates and polygon faces, plus what MTL can express: a diffuse colour, opacity, shininess and a single diffuse texture map. There are no PBR metal/roughness values, no normal maps, no vertex colours and no animation.

Open a OBJ file in the viewer

About this conversion

The shortest possible hop between two plain-text mesh formats. The OFF vertices and faces are written as an .obj with normals computed from the source triangles.

Why convert OFF to OBJ

Get an OFF file into a toolchain that reads OBJ.
Produce a text mesh you can inspect, edit or diff in version control.
Move bare geometry into a shader tutorial or a custom OBJ-based loader.

What happens during the conversion

Geometry

Vertices and faces are written through, faces are triangulated, and normals are computed from the triangles. Everything is merged into a single object, because OFF has no structure. There are no texture coordinates, because OFF does not store any.

Materials and textures

No material file is written, so the .obj has no usemtl line and viewers use their default shading. The converter does hold a material while it has the file in memory, but it is unnamed, and an unnamed material is not written to an .mtl.

Common use cases

Getting minimal geometry into an OBJ-based pipeline.
Producing a text mesh you can inspect and edit.
Feeding a custom WebGL OBJ loader.

Limitations of this conversion

There is no UV layer, because OFF stores no texture coordinates. You will need to unwrap in a 3D application before texturing.
No material or .mtl file is produced, so the model renders with default shading.
Everything is merged into a single object, because OFF has no structure.

How to convert OFF to OBJ

Three steps in the browser. Nothing is uploaded to a server, so an unwieldy file is limited only by your own device's memory.

STEP 1

Upload your .off

The plain-text OFF file is read directly, and vertex normals are derived from the face winding before the .obj is written.

STEP 2

Convert to OBJ

Geometry is written with normals computed from the source triangles.

STEP 3

Open the .obj in your tool

Expect a single object with normals derived from the OFF's face winding, and no UV layer.