AC3D Scene to USDZ Converter
FileFlip converts AC3D Scene to USDZ entirely inside your browser, using Assimp compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an AC3D Scene file to USDZ?#
- Drop your AC3D Scene file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to USDZ and the conversion starts on its own. FileFlip downloads 11.2 MB of WebAssembly the first time and nothing after that, then runs Assimp on your own machine.
- Save the USDZ file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting AC3D Scene to USDZ lose quality?#
Not in the sense of pixels or samples. Converting AC3D Scene to USDZ rebuilds the file in USDZ's own model rather than re-encoding it, so everything USDZ can represent comes through exactly and anything it cannot has to be dropped. Expect the geometry to be exact, and anything the target has no place for, such as a rig, to be left behind.
Is it safe to convert AC3D Scene files online?#
Yes, because nothing is uploaded. FileFlip converts AC3D Scene files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What AC3D Scene to USDZ actually does to the file#
Converting AC3D Scene to USDZ runs on Assimp, downloads 11.2 MB of WebAssembly the first time and nothing after that, rebuilds the file in the target's own model.
| Engine | Assimp |
|---|---|
| Conversion path | One step: AC3D Scene → USDZ |
| Downloaded to your browser | 11.2 MB, once, then cached by your browser |
| Quality | Rebuilt in the target's model |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Materials | Sometimes | Survives for some files and not others. |
| Textures | Sometimes | Survives for some files and not others. |
| Skeleton and animation | Sometimes | Survives for some files and not others. |
What is an AC3D Scene file?#
An AC3D file holds exactly the same plain-text scene data as an AC file, just saved under the modeller's full name instead of the short .ac extension, with the identical hierarchy of objects, surfaces and materials.
Use AC3D when a tool or pipeline specifically expects the long extension rather than .ac, otherwise the choice makes no difference.
Convert AC3D to OBJ or glTF for the same reasons you'd convert an .ac file: almost nothing outside the flight-sim world opens it directly.
What is a USDZ file?#
A USDZ file is a zero-compression ZIP archive holding one or more USD layers together with their textures, audio and other referenced assets, packaged as the single file Apple's AR Quick Look expects.
Use USDZ when a model needs to open in AR Quick Look on an iPhone or iPad, or travel as one self-contained file with its textures attached.
Convert away from USDZ when the model is headed into a DCC tool or pipeline that expects an unpacked USD layer rather than a zip package.
AC3D Scene to USDZ questions people ask#
What's the difference between .ac3d and .ac files?
There is no difference in content. An AC3D file and an AC file store the same plain-text object hierarchy; .ac3d is just the modeller's full name used as an extension instead of the shorter .ac.
What software opens AC3D files?
AC3D files open in AC3D itself, and in FlightGear, which loads this format directly as its native aircraft and scenery model. Because it's the same format as .ac, anything that reads AC3D's short extension reads the long one too, though a few importers only check for .ac by default.
What opens a USDZ file?
On a Mac or iPhone, USDZ opens straight in Quick Look from the Finder, Safari, Messages or Mail with no separate app needed. Blender and Adobe Aero also read USDZ on any platform if you need to edit rather than just view it.
Why is USDZ used for AR on iPhone?
Apple built USDZ specifically as the file AR Quick Look expects, so tapping a USDZ link in Safari or Messages drops straight into an augmented reality view with no app install. It packages the model's textures and audio in the same file, so there's nothing else to fetch.