If you have a model from a CAD tool or a 3D printer workflow, it is probably an OBJ or an STL. Augmented-reality viewers — Android’s Scene Viewer, model-viewer on the web, Unity and three.js pipelines — want glTF, and specifically its single-file binary form, GLB.

What GLB is

glTF is a JSON description of a scene (meshes, materials, nodes) plus a binary buffer of vertex data. GLB packs both into one file so nothing can go missing. It is small, loads fast and is the format the AR ecosystem has standardised on.

What converts, and what does not

Convert Files carries the geometry: every vertex and triangle, with node transforms applied so the model sits where it should. It does not carry materials, textures or animations — an OBJ’s .mtl file and its texture images are not read. The result is a clean grey mesh, which is exactly what you want as a starting point for assigning your own material in a viewer or engine.

Units and scale

glTF is in metres. STL files are unitless and often exported in millimetres, so a 20 mm ring becomes a 20 m ring in AR. Check the scale in your viewer; most let you set it in one field. Convert Files does not rescale, because it cannot know which unit the source used.

Going the other way

GLB to STL is useful for printing a model that only exists as a glTF. Node transforms are baked in, so the printed part comes out at the pose you see in the viewer.