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I am using Apple's new Reality Composer application to attach an image anchor to my .USDZ.

My USDZ file is +/- 5MB when imported to Reality Composer and the reference image is 100KB. When I export my .reality file from Reality Composer, the file size explodes to 17MB.

Andy Jazz
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John Martz
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1 Answers1

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I suppose file size does definitely depend on file format's architecture.

Sometimes the size of .reality file is greater than .usdz, sometimes it's less (however, .reality files have a much faster uploading time than .usdz).

If you manually rename a scene.reality file to scene.zip file and then unzip it on your Desktop (you can do the same trick with scene.usdz and scene.rcproject files), you must see a folder, named assets, containing several binary .arz files. These files describe Reality Composer's scene: its entities, animation, dynamics, anchor types, etc.

Thus, the total number of .arz files defines the size of scene.reality container in MB.

enter image description here

Also, you can find there an assetMap.json file which might look like that:

{
  "scenes" : [
    {
      "sceneIdentifier" : "EDD9ED29-977B-4C2E-A20A-8B073090B950",
            "sceneName" : "Scene",
             "fileName" : "Scene2.compiledscene"
    }
  ]
}
Andy Jazz
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  • The problem is that the .arz files in the .reality file are much larger than the source files. For example texture.jpg is 260kb and the corresponding texture.jpg.compiledtexture.arz file is 1450 kb. Anyone knows how to extract arz file and swap smaller jpg file? – Saico Mar 17 '20 at 11:14
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    It's true. File format dictates file size (the same way `png` is much larger than `jpg`). So `texture.jpg` has a compression algorithm but a `compiledtexture.arz` doesn't. Thus, if you have several compressed 2K `jpeg` textures they may slow down a real-time rendering. In this case it's much better to have uncompressed textures. – Andy Jazz Mar 17 '20 at 11:43