Demystifying USD
Not the currency...this would be a very different newsletter if I could do that...
The first time I heard about USD was about seven years ago.
I walked into the middle of a conversation between an artist and one of our technical leads. They were debating whether they should convert something to USD or if that was too risky. Honestly, I thought they were talking about swapping cryptocurrency for U.S. Dollars—I almost jumped in to complain about currency exchange fees!
Thankfully, I just smiled, nodded, and waited until I realized that I was in a conversation way over my head. I took note and later googled this new file format and have been a little obsessed with it ever since.
A Quick Overview: USD as a “Master Binder” for 3D
Imagine all the components that go into a 3D scene. You’ve got models (the shapes of objects or characters), textures (the “paint” on their surfaces), lighting setups (lamps, the sun, or other sources of illumination), animations (movements over time), and sometimes even audio. Managing all of these can quickly get overwhelming—especially if they originate in different software tools and involve a large team of people.
That’s where Universal Scene Description (USD) comes in. Developed by Pixar, USD is like a super-organized binder for your 3D world, storing everything so that it can be rearranged, updated, and layered without blowing up the entire project.
Why Pixar Built It
Pixar didn’t invent another acronym for no reason. They needed a solution for the massive complexity of their film projects. Picture hundreds of people, each handling different elements of a movie: one team does environments, another handles character rigging, and another creates effects like water splashes or smoke—often using different software that generates various file types. USD’s goal was to let them all work on the same scene, in real time, without creating a tangled mess of file versions. Essentially, Pixar needed a universal language for describing 3D scenes.
The Magic of Layering and Referencing
Where USD truly shines is in its layering capabilities. Picture a large living room you’re decorating for a party. Person A arranges the furniture, Person B sets up the lights, Person C arranges food spread. If everyone tries to work in the same physical space simultaneously, it’s chaos. But life would be much simpler if each person had their own “layer” that could magically combine into a final arrangement.
That’s the core of USD. Every element of the scene can exist in its own layer or file. When you need the whole picture, these layers are merged into a master USD. If someone updates the furniture layer (maybe they tweak the position of a chair), that change automatically appears in the final scene.
But what if the tweak in one layer disrupts something in another? Suppose Person A’s adjustment of a piece of furniture blocks a light source. With USD, Person B can create an additional layer that modifies or fixes that piece of furniture to avoid that issue without permanently altering the original. Think of it like a Photoshop file with layers; if the bottom layers are causing a problem in the final image, you can fix them using new layers on top—no need to destroy the original work.
For a smaller, non-studio scenario, imagine designing a 3D product. Your 3D team handles product details in one layer while the marketing team creates a lifestyle environment in another. If the engineers finalize a design tweak, it automatically appears in the marketing renders—no manual file transfers, no risk of overwriting each other’s data.
USD? USDc? USDz!?!?!
People often talk about “USD files” as if it’s one thing, but you might also see usda, usdc, or usdz. These are different “flavors” of USD, each serving a specific purpose. If you’re new to 3D, think of them like different photo formats.
The usda format (ASCII) is like a RAW or lossless TIFF photo: it’s large, detailed, and human-readable if you open it in a text editor. This makes it great for inspecting or debugging raw data but can make files slower and bulkier.
The usdc format (Binary) is more like a standard TIFF or PNG: it maintains high fidelity, but it’s not human-readable in a text editor. It’s smaller than usda and often loads faster, but you can’t just pop it open and read it.
The usdz format (Zipped) is your JPEG equivalent: everything is compressed into one file, including textures and other assets. It’s ideal for sharing or distributing, especially for augmented reality (AR) applications. Apple, in particular, favors usdz for iOS AR apps. The downside is that usdz is read-only; you’d need to go back to usdc or usda for deeper edits. When someone says “I’ve got a USDZ for you,” it’s basically like handing you a compact snapshot of a 3D scene, much like emailing a JPEG instead of a layered Photoshop file.
Which Flavor of USD Should You Use?
If you’re actively editing or debugging, usda can be handy because you can open it in a text editor and see exactly what’s going on.
But if performance and file size matter more, usdc is probably the way to go.
Then, when you’re ready to send it off to a client or display it in an AR app, usdz is your best bet for a convenient, shareable package—like exporting a JPEG for final distribution
Don’t feel scared…it’ll all make sense soon
How USD Stacks Up to Other 3D Formats
You might be thinking, “Hold on—aren’t there already universal 3D formats like OBJ, FBX, and Alembic (ABC)?” Absolutely. They each have their strengths and weaknesses. But USD’s “secret sauce” is in how it combines the best elements of these formats, while adding layering and referencing superpowers.
OBJ is one of the earliest and simplest 3D file formats, originally developed in the 1980s. It primarily stores the geometry—essentially the shape—of models, along with basic material information. It’s widely supported and great for transferring static models between different software, but it lacks modern features like advanced animations or complex layering. Think of it as a very old file cabinet with neatly labeled drawers for shapes, but no extra compartments for anything fancy.
FBX belongs to Autodesk and can handle more sophisticated data, such as rigs, materials, and animations. This makes it a go-to format when moving elaborate 3D scenes between Maya, 3ds Max, Unity, and other popular tools. However, since FBX is proprietary, you don’t have complete access to its internal workings. It’s like a locked briefcase: the documents inside are well organized, and many people have a copy of the key, but you can’t fully see or modify the structure unless Autodesk says so.
Alembic or ABC focuses on cached geometry, which describes the final positions of assets in complex simulations such as fluids or massive crowds. It’s impressively efficient for playback of heavy data, but it’s not designed for advanced layering or referencing and usually works in a read-only capacity. Think of it as a shipping container: perfect for delivering pre-assembled objects to their destination, but once it’s sealed, you can’t rearrange the cargo within it.
Universal Scene Description, or USD, is designed to handle every aspect of a 3D scene: models, materials, layering, references, animations, lights, and even robust chunks of metadata. Since Pixar made it open source, anyone can adapt or extend the format to fit their pipeline. One of its standout features is layering and referencing, which means you can stack changes on top of existing data without overwriting the originals. This approach works like a well-organized binder with separate sections for each collaborator; you can add or revise pages while always having a neat, single master document that pulls it all together.
USD for Non-3D Folks: Why Should You Care?
Emerging AR & VR Applications
3D and AR are creeping into everyday life—think virtual try-ons for furniture or clothing, interactive product demos, or educational apps. Apple’s love for USDz means you can drop 3D objects right into an iPhone camera view for an instant AR experience.
Simplified Collaboration
USD is collaborative by design. If you’re coordinating with multiple designers, developers, or artists, everyone can keep their portion of the project updated in real time. No more emailing around “final_final_v3” assets and crossing your fingers you open the correct file.
Future-Proofing
Because Pixar open-sourced USD, it’s becoming a standard in major 3D software—Autodesk Maya, SideFX Houdini, Substance 3D, Blender (via add-ons), and more. Over time, that means better compatibility and fewer headaches. If you adopt USD now, you’ll likely avoid tomorrow's file-format wars.
Where USD Stands Right Now: Ready for Prime Time?
Yes, many VFX studios, animation houses, and AAA game developers rely on USD every day. The technology has proven itself on massive Hollywood films with thousands of 3D shots. For smaller teams, USD can still be a fantastic solution, especially if you’re dealing with multiple programs or need an efficient way to keep track of complex scenes.
However, like any advanced tool, it comes with a learning curve. You may need to install specific plugins or update your favorite 3D software to ensure smooth USD support. But once it’s set up, the payoff in organization and efficiency can be huge. And as more companies (including Apple, Nvidia, Epic Games, and major DCC software vendors) jump on board, the ecosystem around USD continues to expand.
The Future of USD
Many studios are implementing USD into their pipelines, but there are still hurdles. Software sometimes processes USD data differently, leading to inconsistencies. Individual artists may not always have the technical expertise to debug issues without help from pipeline engineers.
In the future, I’d love to see USD simplified. From my experience, most artists are equally excited about USD’s potential but also wish they didn’t have to think about it too much. They want to use its features without needing to become experts in file management or coding.
User-friendly tools that make USD more accessible could help bridge this gap. Imagine a drag-and-drop interface that lets artists layer and reference seamlessly without touching a line of code. Whether I’m predicting this or just willing it into existence, time will tell.
Closing Thoughts
Despite its acronym’s overlap with “U.S. Dollars,” USD (Universal Scene Description) is a different kind of currency—one that buys you organizational freedom, smoother collaboration, and future-proof flexibility. As 3D continues to infiltrate e-commerce, product design, architecture, and interactive media, USD is poised to become the behind-the-scenes hero that keeps everything and everyone on the same page.
If you’re a 3D artist, incorporating USD into your pipeline can streamline your workflow and reduce file-format headaches. If you’re a project manager, USD makes collaboration smoother and iteration cycles faster. And if you’re a curious tech enthusiast, keep an eye on USD’s growth—it’s already changing how we interact with digital content.
The next time you see a usda, usdc, or usdz file, remember: it’s more than just a mysterious extension. It’s Pixar’s gift to the 3D world, a universal binder for all things digital, and perhaps the new creative currency for years to come.
The 3D Artist Community Updates
This week, we are thrilled to be joined by Chad Knight!
Chad, a brilliant 3D footwear designer, drives innovation by transforming workflows and integrating emerging technologies. Combining technical expertise and creative vision, he enhances user experiences and uncovers intuitive solutions through his keen eye for patterns and insights.
3D Merch is here and we have a new hoodie!
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Hello! Michael Tanzillo here. I am the Head of Technical Artists with the Substance 3D Growth team at Adobe. Previously, I was a Senior Artist on animated films at Blue Sky Studios/Disney with credits including three Ice Age movies, two Rios, Peanuts, Ferdinand, Spies in Disguise, and Epic.
In addition to his work as an artist, I am the Co-Author of the book Lighting for Animation: The Visual Art of Storytelling and the Co-Founder of The Academy of Animated Art, an online school that has helped hundreds of artists around the world begin careers in Animation, Visual Effects, and Digital Imaging. I also created The 3D Artist Community on Skool and this newsletter.
www.michaeltanzillo.com
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Great explanation!
This is a great overview. Thanks!