GLB to OBJ converter

What the OBJ keeps, and what it loses

How to convert a GLB to OBJ

1. Drop the GLB on this page, or choose it with the button. For a glTF, drop the .gltf with its .bin and picture files, or a ZIP of its folder.
2. Look at the model, its size and its objects.
3. Choose the unit under Unit of a saved STL, OBJ or PLY: millimeters for a slicer or CAD, meters for Blender.
4. Choose Download OBJ. With colors you get a ZIP with the OBJ and its material file; without, the OBJ alone. Both are named after the GLB.

Names, colors and the material file

Each mesh of the scene becomes an o object in the OBJ, named after its node in the GLB, with spaces turned into underscores, since an OBJ name is one word. A mesh drawn in several places is written once for each place. A mesh with several materials is an object for each, named after the glTF mesh as three.js numbers it (Body, Body_1), and so is a mesh whose node has no name. A mesh named nowhere is called mesh_ and its number in the file, as three.js names it. A scene of more than 12 million vertices, counting each mesh as often as it is drawn, is more than can be written as one mesh here, and the page says so when you save it.

Each color becomes a material in the MTL, with the color as the material’s diffuse color (Kd), which is what every program that reads OBJ takes from it. A mesh whose vertices carry colors of their own keeps them: as a material for each color when there are up to 32, and otherwise as a color after each vertex, which Blender, MeshLab and this site read.

glTF’s materials are more than a color: a texture, how rough and how metallic the surface is, a light it gives off. None of that has a place in an MTL that programs agree on, so the OBJ has the color alone. A model whose look comes from its textures arrives in the color its material multiplies them by, often white.

Size and orientation

A GLB states its unit, meters, and its up direction, Y. An OBJ states neither, so the program that opens it assumes them. The numbers are written in the unit you choose, millimeters to begin with, which is what slicers and CAD programs assume. Blender assumes meters: for Blender, choose Meters, or set the scale when you import. The axes are kept as they are, Y up, which is what Blender and most modeling programs assume of an OBJ.

OBJ, STL or glTF

• OBJ is read by nearly every 3D program, old and new, and is text you can read.
• STL is for a slicer: one mesh, in millimeters, standing on Z.
• glTF keeps everything the GLB has, textures and animations included, as separate files you can edit.

The STL and the glTF, and a 3MF and a PLY, are saved from the links under the button.

Questions