How Nuke, Mari, Katana and Modo are adopting USD.
The technology that is changing VFX and animation pipelines around the world is USD—Pixar’s open source Universal Scene Description.
USD is all about enabling a common method for 3D data to be interchanged between different content creation apps. Because USD encompasses a complete specification for 3D scene content, that is, not specializing in only geometry translation or animation transfer, it is quickly gaining user interest as the most complete and most robust way to move data around a multi-product tool chain.
For this reason, Foundry has jumped head-first into adopting USD in its diversified offering of flagship tools, including Nuke, Mari, Katana and Modo. The company has also been taking advantage of USD workflows in several research projects. Here’s how USD is becoming a bigger part of Foundry’s ecosystem.
USD in Nuke now, and what’s coming
The recent Nuke 12.2 release implemented USD ingest, starting with support for reading geometry in USD via Nuke’s ReadGeo node. In the next release, support for reading USD data will be coming to Nuke’s Camera, Axis and Light nodes, according to Christy Anzelmo, Foundry’s Director of Product – Compositing & Finishing.
“To ease the transition to USD for artists, our approach has been to extend the native 3D nodes in Nuke, allowing artists to continue with the workflow they are used to,” Anzelmo says. “The extensions to the nodes are being open sourced so that pipelines can further extend and customize these nodes for their unique USD setup.”
“USD ingest is only the first step to support USD technology in Nuke,” adds Anzelmo. “We have some other projects in the works that will utilize USD to offer a more consistent user experience with other applications.”
As these features take shape, customers are already starting to take advantage of USD in their compositing pipelines.
“We tend to see studios that have either created a custom USD workflow that can be quite advanced, or those starting to experiment with USD using Nuke’s native support,” observes Anzelmo. “Currently, the USD support in Nuke will allow you to bring in the data types that are regularly used in Nuke today, including geometry, cameras, lights, and axes. This means if you’ve started using USD elsewhere in your pipeline, you can continue to use it to carry the data you need directly into Nuke without converting to a different format.”
“As more studios expand their use of USD in Nuke, we’re looking forward to extending support further and taking advantage of USD’s unique attributes to enable more non-destructive workflows across stages of the pipeline.”
Katana: lookdev and lighting and Hydra
One of the key aspects of USD is Hydra, the imaging framework that connects multiple front-ends and backends and ultimately enables rendering. Foundry’s Katana has adopted Hydra to provide for additional benefits to artists in the lighting and lookdev tool.
“At the base level, Hydra is a system that was designed to power viewports at the large scale that Katana is often deployed to produce,” details Jordan Thistlewood, Foundry’s Director of Product – Pre-production, LookDev & Lighting. “It is not a viewport itself but the foundation on which one is built. So as viewport rendering technology evolves and something other than HdStorm is available we can provide that option to users.”
Thistlewood explains that Hydra unifies the viewport shaders, lights and other related aspects, meaning that users can choose the best output for the job. “This also makes Hydra a great tech to build a viewport system on top of for multiple DCCs. We live in a world where it is a reality that artists use multiple tools. Hydra presents the opportunity to have everyone view the scene the same way. Given the tools in Katana for look development it means that an artist can create the shaded and lit appearance of production setups that can then look the same in Houdini, Maya, Modo, etc.”
Outside of Hydra, the implementation of USD into Katana gives artists the ability to provide clients with a way to get production data in and out of the tool with “less fuss and with more sophistication,” suggests Thistlewood.
“As more tools support USD it will allow everyone to use the best tool for the job, and with Katana’s specialization for look development and lighting it opens a lot of doors for the industry to embrace the best workflow at every step of the production process.”
Mari and USD
Meanwhile, 3D painting and texturing within Mari is also benefiting from USD developments at Foundry.
“The Mari team have recently taken ownership and open sourced a mesh importer plugin for USD originally developed at Pixar,” outlines Thistlewood. “The plugin currently only supports mesh and transformations. Though they are not currently supported yet, our intention is to build on this plugin to potentially add support for more of USD’s shading, camera and lighting features.”
“From a look development standpoint, we see USD as an excellent transport format for interop workflows between Mari and Katana and plan to fully explore these opportunities in the future.”
USD in Modo: modeling, texturing and rendering
Modo already has a well-known shared focus on workflow and technical innovation, including a novel rigging and animation system. Streamlined USD import/export for industry-standard exchange means, says Shane Griffith, Director of Product – Digital Design at Foundry, that “Modo can seamlessly slip into any production workflow needing faster modeling and texturing tools that make the lives of artists easier, and is poised to redefine rigging and animation across design and entertainment industries.”
“With USD import and export in Modo 14,” continues Griffith, “artists can reliably exchange geometry, curves, lights, cameras, materials, and animation with several other common applications in a production pipeline.”
The Modo video below shows an attic scene by Volker Troy from pixelwerk. He notes: “USD Import and Export in Modo 14 gives me the option to work with USD assets, whether it be importing existing assets or export assets to be used further down the pipeline in other applications. The import also supports shading and textures. This is the NVIDIA attic scene imported into Modo. All shaders and textures were part of the USD file and were imported directly without any additional tweaks.”
Deeper into USD: research at Foundry
Recent and ongoing research projects at Foundry have also been informing USD developments within its VFX tools, and helping to further understand how USD can be part of studio workflows. Head of Research at Foundry, Dan Ring, highlights the recent EIST project that was conducted in partnership with the BBC.
The aim of the project was to build a tool for quickly importing 3D assets, laying them out and creating dynamic sequences for immersive experiences. The video below is a prototype of the layout tool made only for research purposes for the EIST project.
“The most interesting part of the project was exploring USD as the technology to underpin all of this,” says Ring. “From this we built our ‘Heist’ tool, which was essentially ‘usdview’—a utility tool supplied with USD—on steroids. It allowed users to bring in their models and start building out their stage, all on a Hiero-like timeline. It sits somewhere between a layout and previs tool which exposed and leveraged all of USD’s features such as variant sets, instancing and non-destructive editing, and then used the selected Hydra delegate to visualise or render the scene. It also allowed some tweaking of textures from a preset library to do basic lookdev and material assignment.”
“In addition,” describes Ring, “one of the things we learned was how to present all of the various operations that compose the stage under the hood to users. This was particularly difficult when you start using referencing in a serious way. It was hard in Heist to expose everything that was going on. We’ve since been experimenting with in-memory, non-destructive working with USD files using special nodes within the Nuke graph to specify the operations, where the layering of operations is much clearer to the user, and allows more powerful USD workflows.”
Ring notes too that building the tool helped Foundry figure out the limitations of the technology (these limitations included lack of time support, interpolation, complexity to integrate), but that, more importantly, it “showed the promise of the technology, and the potential of its philosophy. That is, when used correctly, it accurately reflects your pipeline. Instead of seeing it as a file or geometry format, it’s the superposition of every decision made during the production, with the outcome of every stage layered into it.”
USD, the future and Foundry
Clearly, Foundry is committed to bringing USD even further into its product base and helping artists and studios implement the framework into their own pipelines. There’s good reason to do so; USD looks on track to take its place as a cross-industry standard, a point made by Dan Ring, who says that USD solves a number of problems around scene representation that makes it map conveniently to modern production workflows.
“However,” Ring notes, “USD still has some way to go before it is the industry standard. The promise and potential can be seen in it, but there are several practical challenges around it that impede adoption. The first is the very practical challenge of libraries and standards, how does everyone lock down on a specific version—like with the VFX reference platform—or if you don’t want to lock down do you need someone skilled in patching and compiling vendor tools against a per-facility version of USD from scratch?”
“The next challenge,” continues Ring, “is how you use USD, there is very little consensus or best practices on how to structure your USD files, eg. naming, the roles of variants, referencing. Not only does this make it difficult for software vendors to support all the different ways a file can be constructed, but it means decisions on structure and use are made due to constraints on the current show or pipeline. In both cases, standards around library versioning, structure and use are key to driving adoption at scale.”
Still, as more software makers like Foundry take on the interchange aspects of USD, as more studios implement it into their pipelines, and as artists see the direct benefits in their work, there’s a significant force behind making USD an industry standard.
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