Convert FBX to USDZ

Why convert FBX to USDZ?

FBX to USDZ is what you reach for when a model from a game or animation pipeline has to open in AR on an iPhone or iPad. USDZ is the file AR Quick Look reads from Safari, Messages, Mail and Files. The conversion carries the meshes, hierarchy, materials and textures. FBX files often use centimetres, and USDZ is defined in metres, so MeshShift converts the scale so a 30 cm object really is 0.3 m in AR. Skeletal animation, rigs and blend shapes are not exported by this converter, so the USDZ shows the model in its current pose. Materials are mapped to USD's preview surface, so basic colour and texture maps look right while complex shaders are simplified.

How to convert FBX to USDZ

1. Drop your FBX file (with its textures, if separate) onto the converter — it opens in your browser, nothing is uploaded.
2. Check the preview and the dimensions in mm; fix units or the up axis in “Units & orientation” if the size or orientation looks wrong.
3. Choose USDZ as the output and click Convert. Several files download as one ZIP.

What carries over from FBX to USDZ

What changes

• Centimetres are converted to metres so AR placement is correctly sized.
• Animations, skeletons and blend shapes are not exported.
• Materials are simplified to USD preview surface.
• Textures are packed into the USDZ.

Tips

• Check the model's pose before converting; it is exported as it appears in the FBX.
• Test on a physical iPhone to check scale, lighting and colours.
• Reduce polygon count and texture size for smooth AR on older devices.
• Include the texture images when uploading if the FBX references external files.

About FBX files

FBX began as Filmbox, a motion-capture tool from Kaydara, and Autodesk bought it in 2006 and kept developing it as a proprietary format. It has no public specification; the supported way to read or write it is Autodesk's FBX SDK, and other tools rely on that SDK or on reverse-engineered code. There is a binary encoding and an older ASCII one. FBX is more than a mesh container: it stores scene hierarchies, materials, cameras, lights, skeletons, skinning weights and animation takes. For that reason it became the usual bridge between modelling and animation packages such as Maya and 3ds Max and game engines such as Unity and Unreal. Scale and axis conventions vary by exporter, with centimetres being the common default, so an FBX can look wrong in a different program until the unit and up-axis settings are checked.

About USDZ files

USD, Universal Scene Description, was created at Pixar for film production and released as open source in 2016. USDZ was introduced by Apple and Pixar in 2018 as a single-file, uncompressed and unencrypted zip archive that packs a USD scene with its textures so it can be delivered and displayed without extra files. Apple built USDZ into iOS, iPadOS, macOS and visionOS: tapping a .usdz link in Safari or Messages opens AR Quick Look, where the object can be placed in the room at real-world scale. The file format is aligned with USD's metersPerUnit and upAxis metadata, and uses physically based UsdPreviewSurface materials. Retailers use it for product previews, and the format also appears in Reality Composer, Xcode and Blender's USD exporter. It is a viewing and AR format, so it plays no role in slicing.

3D printing notes

Slicers do not take FBX, so the file has to be converted to a mesh format first. Animation and rigging are irrelevant to printing, so only the posed geometry matters. Many FBX models are in centimetres, which means a character that is 18 cm tall in the file must end up as 180 mm; reading it as millimetres gives 18 mm, and reading it as metres gives a huge model. MeshShift defaults FBX to centimetres, shows the real dimensions, and lets you change the unit. It reads FBX but does not write it, so a typical path is FBX to STL or 3MF, followed by the print check to close holes between separate body parts.

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