Unlocking collaborative workflows with USD

Unlocking collaborative workflows with USD

With the growth of technology, tools for collaboration are more prolific than ever. In the film world, there are video collaboration tools like Frame.io; for programmers, there’s Git and other version control systems. Collaboration tools for 3D artists have historically been less than perfect. Sharing 3D files is complex, and there are dozens of “standard” 3D file formats, endless dependencies, and wide variance in the tools each artist uses.

In this article, we’re looking at how the Universal Scene Description (USD) standard works to solve the problems of 3D collaboration. USD allows artists to collaborate and share files so that they always know what to expect when opening and working on files. From look development to shading to rendering on a render farm, we’ll examine how USD makes collaborative workflows easier for artists and studios.

The birth of a new standard

Pixar’s research and development team first developed USD as a tool for solving their own studio’s collaborative bottlenecks. Pixar formally began working on USD in 2012 as they sought to shift their scene development pipeline to an approach that could unify their workflows and tools. The initial result was a format that worked with their internal tools TidScene, Presto, and Hydra, to form a complete pipeline for creating and rendering 3D images. In 2016, Pixar open-sourced USD under an Apache license for the entire 3D industry.

Unlocking collaborative workflows with USD
USDView, Pixar’s USD viewer utility, allows artists to preview USD files quickly. | Image Credit: Blender Foundation

Since its release, USD has slowly been integrated into most professional 3D tools, including most 3D and CAD software from Autodesk, Adobe, Maxon, Apple, and other open-source tools like Blender. USD has quickly become an industry standard because of its open-source nature and because it is an efficient and quality tool that simplifies artists' workflows. Apart from 3D software alone, USD has also become the backbone for many other innovative technologies, such as NVIDIA’s Omniverse platform, which is entirely based on USD for its handling of 3D files.

The advantages of using USD

What makes Universal Scene Description special is that its modern architecture allows it to perform huge tasks on behalf of the artists with little latency. Because of the open-source nature of USD, its implementation varies widely between workflows, studios, and software. However, its core concepts remain the same, and USD files from software to software will largely work as expected, regardless of if each software takes full advantage of the USD tool set.

Collaboration is obviously one of USD’s top features, with version control being no small part of what makes it unique. When multiple artists are working on a project, USD uses layers to separate out each user’s work and when figures out which change to apply to the final scene using each layer’s “opinion strength,” which is based on the characteristics of each user’s layer. This method takes advantage of the fact that USD files can be merged and manipulated by overlaying multiple files and folders into a single scene. This means that a USD project can range from being as simple as a single 3D model file to an entire project tree of USD files.

Unlocking collaborative workflows with USD
USD projects contain multiple sub-layers and files to form a scene. | Image Credit: Pixar

This brings us to USD’s other major advantage: scalability. USD was designed from the top down to be functional for both the largest studios and the smallest projects. This means the USD can effectively scale with the growth of a project over its lifespan without becoming bloated. USD’s architecture is multi-threaded and GPU-accelerated, so it can handle large workloads without struggling. Scalability was one of Pixar’s largest concerns when building USD, and it stands up to the tests. USD is in use at some level by most major studios and is also used by many small teams to organize and maintain scenes.

How USD is changing online rendering

Universal Scene Description also changes how prepping scenes for rendering locally or on a render farm are done. The ubiquity of USD as a 3D file standard allows scenes to be easily imported to render engines and render farms without requiring total scene reworks or rebuilding of a scene’s lighting and shading.

Rendering was one of Pixar’s top concerns when building USD. Pixar’s Hydra rendering tool was built alongside USD during development as a mediator between 3D scenes and renderers to speed up production. USD and Hydra allow artists to use multiple render engines to render a scene for look dev, previewing, or final render farm rendering. Tools using Hydra and USD are already being released for use in rendering, including some open-source tools like AMD’s Blender USD Hydra Add-on that can be used to assemble and render USD scenes for Blender and a wide variety of compatible render engines.

Unlocking collaborative workflows with USD
This demo scene from Animal Logic’s ALab shows how flexible USD projects can be. This scene was importanted into a DCC app, and previewed in seconds without any manual modifications or major errors.

Using tools like USD and Hydra can significantly optimize rendering, especially for large projects. USD stores files in a way that is quickly accessible and usable by render engines, meaning that scene build times will be significantly decreased in an all-USD pipeline. Much of this efficiency is a byproduct of Pixar’s early work to optimize USD for OpenGL real-time previewing inside Pixar’s Presto animation tool. But the optimizations have grown to have a huge effect on all areas of rendering, leading to much lower local and online render farm costs for studios.

Wrapping up

Adopting Universal Scene Description is already bringing some important benefits to artists, studios, and online render farms, including improved efficiency, scalability, compatibility, and the standardization of workflows and files across different tools. File compatibility and version control systems have long been some of the most significant technical pain points for 3D creatives, so it’s great to see that USD is enabling ways to resolve these issues.

If you want to learn more about Universal Scene Description and how you can integrate it into your workflow, check out your digital content creation tool’s documentation. Or, if you’re feeling adventurous, you can download standalone builds of Pixar’s USD tools from NVIDIA here, including Pixar’s USDview application. USD workflows are supported by almost every major software available, so odds are, you’re already ready to implement USD into your workflow!

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