USDZ File Not Loading on iPhone 7

Question

Our USDZ file won't load on iPhone 7 with iOS 12. It works fine on my iPhone X and iPad Pro, both running iOS 12 Beta.

We've tried creating this using the terminal commands and get the following warning although we don't believe this is the issue.

Warning: in CreateMaterialBindings at line 59 of /BuildRoot/Library/Caches/com.apple.xbs/Sources/3DAssetTools/3DAssetTools-14207.2/external/ModelKit/extern/usd/pxr/usd/usdObj/translator.cpp -- OBJ mtl usemtl name has invalid name '15___Default', using default usemtl name: 'defaultShadeGroup0' 

The screen on the iPhone 7 looks as such:

You can download the raw files here.

Answer 1

You can't see your 3D model because you're using very bad naming convention for file model2_$$usd_converter$$_.usdc inside usdz container. In macOS and iOS you have to avoid using $ in file names, because dollar sign is a special character.

Follow these two steps to unzip, rename and rezip your usdz file.

First Step (unzip mmtest.usdz file)

To unzip a usdz file in macOS Mojave use the following method:

• In Finder change the extension of .usdz file to .zip.
• Uncompress .zip file using Archive_Utility.app or RAR_Extractor.app.
• Open unzipped directory and change files' names.
• Make sure all textures are in JPG and/or PNG format.
• Make sure 3D normals of your USDC model ain't inverted.

Second Step (recreate usdz again)

Make sure that Xcode 10.2 is installed.

To convert a content of unzipped folder (binary usdc file and its textures) to usdz file format again, use the following command in Terminal.app:

cd ~/Desktop/mmtest/


xcrun usdz_converter Model.usdc Model.usdz 
-g SofaMesh
-color_map Diffuse.jpg
-roughness_map Roughness.png
-normal_map Normal.jpg

And here are a full list of options (type xcrun usdz_converter -h in Terminal):

-g groupName [groupNames ...]        Apply subsequent material properties to the named group(s).
-m materialName [materialNames ...]  Apply subsequent material properties to the named material(s).
-h                                   Display help.
-a                                   Generate a .usda intermediate file.  Default is .usdc.
-l                                   Leave the intermediate .usd file in the source folder.
-v                                   Verbose output.
-f                    filePath       Read commands from a file.
-texCoordSet          set            The name of the texturemap coordinate set to use if multiple exist (no quotes).
-opacity              o              Floating point value 0.0...1.0

-color_default        r g b a        Floating point values 0.0...1.0
-normal_default       r g b a        Floating point values 0.0...1.0
-emissive_default     r g b a        Floating point values 0.0...1.0
-metallic_default     r g b a        Floating point values 0.0...1.0
-roughness_default    r g b a        Floating point values 0.0...1.0
-ao_default           r g b a        Floating point values 0.0...1.0

-color_map            filePath
-normal_map           filePath
-emissive_map         filePath
-metallic_map         filePath
-roughness_map        filePath
-ao_map               filePath

Now model works perfectly.