I'm looking for documentation/guidance on USDZ and scene model sizes. My focus is on RealityKit-based apps.
I found the 2018 WWDC presentation
Integrating Apps and Content with AR Quick Look
which mentions a rule of thumb for a USDZ model of:
- 100K polygons
- One set of 2048x2048 textures
- 10 seconds of animations
Are these number still recommended in 2021?
Are these numbers just for Quicklook, or do they apply to RealityKit-based apps too?
If a RealityKit scene loads several USDZ models, should the cumulative number of polygons across all models be 100K, or is the 100K number on a per-model basis?
The talk mentioned AR Quicklook will dynamically downsample textures for devices with less memory. Does RealityKit do this as well?
If so, can I error on providing a larger texture (e.g., 4096 x 4096) and trust RealityKit to downsample as appropriate for me?
(I am hoping there is some documentation covering questions like this)
For AR Quick Look, the specifications you mentioned are still what we recommend. However, our specifications are meant to ensure that all of our supported devices (down to iPhone 7) can load and display the model well. That being said, if you are only concerned about supporting more modern devices, you could increase the detail of your models. AR Quick Look uses RealityKit under the hood, so it should support downsampling textures. If you are planning to make a RealityKit app, you also have a bit more wiggle room on model size. You could generate multiple versions of your model and use different model depending on the power of the target device. So in general, keep the recommended specifications in mind, but you can go over them if you want to support newer devices only.
