All about Apple’s new USDZ File Format — Simplified

Created by Suren Konathala

Apple at the WWDC Conference 2018, announced that it has developed a new file format, working together with Pixar, called USDZ Universal. This file will allow developers to create 3d models for augmented reality.

Why the new file format?

USD — Universal Scene Description, was developed by Pixar. The file has the ability to create a 3D scene by composing many sources files together into successively larger aggregations. This is great but this can be a problem using USD to deliver assets in the form that they have been built up. There is a no mechanism for representing images/textures as scene descriptions encodable in USD files. Also these assets can be delivered on a variety of systems and platforms if it is a single object, can be streamed and usable without unpacking to a filesystem.

Consider any Digital Asset Management (DAM) system, even though they are sophisticated to allow to host, manage and render assets, the assets need to be a single object. Overlays and layers maybe available on some systems (Like on Adobe experience manage by using Dynamic Media we can achieve text overlays). For 3d models, generally they are a combination of several objects (images and text).

Adobe CTO Abhay Parasnis announcing the support for usdz file format at Apple’s WWDC 2018. Image source https://www.apple.com/newsroom/2018/06/highlights-from-wwdc-2018/?imgid=dc16a78fa6cdb387ae425b980e9d774f

To address these concerns and by leveraging USD, Pixar and Apple developed this new file format with the .usdz extension, which is a combination of several objects but can still be rendered as one object.

Specifications

  • Base: USDZ file is a zip archive
  • Zip constraints: A USDZ file is a no compression, unencrypted zip archive
  • File types: A USDZ file can contain only file types whose data can be consumed by the USD runtime via mmap. Initially this will only include the native USD file formats and a small number of image formats.
  • USD Constraints: A USDZ file is read-only. Editing its contents requires unpacking the archive and editing its constituent parts using appropriate tools.

How to create USDZ files

  • Vectary released an update to export 3D designs to USDZ. Learn how to create USDZ files here. (update October 2nd, 2018)
  • No open-sourced/free tools yet in the market (as of October 3rd, 2018)

Sample USDZ files

  • Download sample USDZ files on my github (update October 2nd, 2018)

Resources

  1. Introduction to USD
  2. Pixar’s open source github project on USD files
  3. Universal Scene Description Project
  4. USDZ File Format Specification

Naturally, if you enjoyed reading this, i’m always looking for curious people to write/talk about tech. Or, if you just want to talk ping me up on twitter any time @surenkonathala