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USD for Visual Effects | TD Meetup 06

USD is becoming an important standard file format for visual effects, animation and video game productions. Most of us have heard of USD, but what is it and how to use it in our next production is still a mystery to most.


Let's find out about USD together!




What is USD?

"USD stands for “Universal Scene Description.” It is a system for encoding scalable, hierarchically organized, static and time-sampled data, for the primary purpose of interchanging and augmenting the data between cooperating digital content creation applications.


USD also provides a rich set of composition operators, including asset and file references and variants, that let consumers aggregate multiple assets into a single scenegraph while still allowing for sparse overrides." [Source: OpenUSD]


Simply put USD is a file format:

.usda

Human-readable UTF-8 text

Manually readable & updatable

.usdc

Random-access “Crate” binary

Faster render, slower update

.usd

Either of the above

 


Let's compare USD with other file formats:

USD vs other file formats
USD vs other file formats

USD is the best and most flexible file format out there but it is much more ...



Why USD?

Pixar created USD as a universal scene description as a can-do-everything file format but it has many more additional features:


  • File Format: Universal use in every department and DCC.

  • Integration: Plugins support reading and writing Alembic files and reading MaterialX files. Read and write other file formats by translating the data to the USD scenegraph.

  • Performance: Fast loading and low latency (multi-threading and GPU).

  • Collaboration: Layers allow artists in different departments to work on the scene at the same time.

  • Variations: Introduce new variations for all instances of an asset in a particular context (set, sequence, shot, etc.).

  • Programmable: C++ libraries accessible via Python to manipulate USD.



Layers

A huge issue in every production is the creation of the final asset and scene. A variety of artists and departments work together to create one or multiple versions of a final asset or shot. USD offers the concept of layers to help with those creations while keeping the changes non destructive.


Similar to layers in Photoshop we can add and overwrite our scene with additional layers which allows for multiple layers for each department and individual overwrites for custom assets and shots.


USD Layers for final shot creation
USD Layers for final shot creation

Another benefit of being a universal scene description is that USD can be used in all supporting DCCs while layers allow different departments from different software packages to add the same asset or shot:


Parallel cross-platform working
Parallel cross-platform working

Open USD

Pixar's USD is an Open Source project on GitHub that gives us access to its source code. This makes custom overwrites and a communitybased collaborations possible.


OpenUSD on GitHub
OpenUSD on GitHub

Resume

USD defines the future of file formats and production workflows, with the biggest studios (DNEG, Animal Logic, ...) already on board with the new format. Learning and understanding the basics of USD is becoming essential for any artistic or technical career. It also improves our chances of employment if we are familiar with the format of the future.


Our recommendation is to at least understand the basics of USD while playing with the USD test scene to get a feel for the new format. To learn more about USD check out the USD Crash course for VFX by Bertrand Cabrol and sign up for the Python for USD wishlist.



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