FBX is Autodesk's interchange format and the de facto standard for moving rigged and animated content between applications.
What it carries
- Geometry, with multiple UV sets
- Materials, in a pre-PBR model
- Textures, embedded or referenced
- Skeletons, skin weights, multiple animation takes
- Morph targets
- Cameras, lights, scene hierarchy
- Custom properties
Why it persists
Animation. FBX has carried rigged content reliably for two decades, every professional tool reads and writes it, and studio pipelines are built around it. glTF is technically better in most respects and has not displaced FBX where complex animation is involved.
The material problem
FBX's material model predates PBR. Exporters map modern materials onto it approximately, and importers map them back approximately, and the two approximations rarely agree. Expect to rebuild materials at the destination — this is normal, not a fault in your export.
The unit problem
FBX stores a unit scale, and applications disagree about whether to apply it or record it. That disagreement is the source of most models arriving at 100× or 0.01× their intended size. Configure the exporter and importer as a pair once per tool combination and stop treating each instance as a new mystery.
ASCII and binary
Binary is smaller and faster. ASCII is readable and diffable, which is occasionally useful for debugging and for version control. Binary for anything routine.
Versions
FBX has versioned repeatedly and older importers cannot read newer files. When an FBX will not open, the version is worth checking before anything else — exporting to an older version usually resolves it.
When to prefer glTF
Static assets, PBR materials, web delivery, and anywhere you would rather not rebuild materials. Keep FBX for skinned, animated content and for pipelines that already assume it.