USDZ Meter Scale Issue

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Created Nov ’22

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I have two USDZ files, the Cube one was created using Blender and has a size of 10cm, the RetroTV one was provided by apple in the AR Quicklook Gallery. The issue is that after loading them the TV shows to scale, but the cube is too small to be seen.

From what I had understood, and seen in the WWDC talks, the unit of measurement in RealityKit is the meter, so in the case of the Cube 0.1 meters is 10 cm. But that means that the tv is supposed to be 84m in width, and that can't be right, specially if the model is coming directly from Apple.

I also tried converting both to USDA and both of them have metersPerUnit = 1. The only way I could find to make it work is after loading the square entity into RealityKit I can then change the scale to [1, 1, 1], but if I do the same to the TV it becomes huge.

What am I missing in here, what's wrong?

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Answer 1

tuskuno OP

Nov ’22

How are you getting your Blender Cube to USD? The standard cube in Blender is 2×2×2 meters, when I export it as OBJ and load it into Reality Converter it is suddenly 2×2×2 centimeters, which leads me to believe the standard unit of measurement is centimeters not millimeters.

I suggest loading your objects into a Reality Composer scene to test the scale (see image). Once that's figured out I assume you can take these settings over to Xcode. The gray cube is from Blender, the white one is the standard 10cm one from Apple and I assume you are familiar with the TV.

Screen Shot 2022-11-04 at 16.48.42.png

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