Interview with Ernest Petti, Revealing the Production Secrets of Frozen 2
During the visual and information feast - SIGGRAPH Asia 2019, Fox Renderfarm is delighted to have the chance to talk with Mr. Ernest Petti, Studio CG Supervisor at Walt Disney Animation Studios, who has also devoted to the production in Frozen 2, the biggest-worldwide-opening animated film of all time.
Ernest Petti has been working with Walt Disney Animation Studios for over 19 years, now is the Studio CG Supervisor. In this role he acts as a bridge between Production and Technology for long-term strategic initiatives, orchestrating the initiatives and projects of the Workflow team and uniting them to fit within the studio’s vision for workflow. Prior to this, he served as Technical Supervisor on Ralph Breaks the Internet (2018) and the 2016 Oscar-winning feature Zootopia. Ernest joined Disney in 2000 as a software engineer in the Technology group and has served as a supervisor in Lighting, Look Development, and Tactics. Credits include 2014's Oscar-winning feature Big Hero 6, as well as Wreck-it Ralph (2012), Tangled (2010), and Bolt (2008).
In the Featured Sessions of SIGGRAPH Asia 2019, Ernest delivered a presentation named - "Frozen 2" and the Past, Present, and Future of Tech at Disney Animation, and he was also being part of the discussion and communication: Proactive Large-Scale Pipeline Efficiency Management, with a panel from large-scale Animation and VFX studios to share insights to their challenges on how to balance between creating amazing visuals as well as given a tight production time frame.
During our interview, Ernest expressed his excitement about this year’s SIGGRAPH - how interested he was to connect with other people, companies and technologies. Besides, among all the cutting-edged technologies shown, machine learning sparks his curiosity about its application during his work. Of course, the development of rendering technology arouses his wonder about how to make a more interactive and direct manipulation with rendering, especially with GPU that comes along.
More insights into the production of Frozen 2 is definitely what Fox Renderfarm would not miss, and are also what we can’t wait to share with you. Let’s check out the interview video and article, and see how Walt Disney Animation Studios combines timeless storytelling with innovative technology.
(F=Fox Renderfarm, EP=Ernest Petti)
F: Could you tell us your main responsibilities in Frozen 2? How did you cooperate with the VFX departments along the production?
EP: My role is Studio CG Supervisor, I’m in the studio level position that kind of overlooks the long-term technical development and artistic workflows over the course of shows.
I work closely with the technology group and with the productions, and try to find the bridge between those over time. I was the Technical Supervisor on Ralph Breaks the Internet. On that show, we did stuff like the first steps into nested proceduralism for some of the buildings on the internet that paved the way then, and was built on top of further for Frozen 2. So there is that sort of continuity of shows that we passed on. And then in my current role, looking at workflow is a big thing that we are focused on and is in the concurrent collaboration and making that as smooth as possible between different departments. So talking to the groups in Frozen 2, like all the Visual Effects Supervisor like Steve Goldberg and the Technical Supervisor like Mark Hammel, and working with them and understanding what they're doing on their show, and making sure it's in line with the shows before, and moving into the future so that we can really build to what will come next.
Basically, when the new set of leadership starts on a show, we try to connect with them, then start understanding what our show’s specific needs, and what are things that we want to advance in the studio that makes sense to, also try to dock on at that show so that we can have some continuity.
F: How did you cooperate with the Production Director and the Production Designer to actualize the creativity through the technologies?
EP: When that story starts forming and the show leadership really is working with the Production Designer and with the Director to understand the story and what the look of the film is, achieving that comes first. So we really want to partner closely on what technology might be needed to make that happen. It’s very important that we’re able to achieve that. Then in partnership with that, it’s can that build off things that were already in the plan; should that accelerate things that we may have been thinking about but weren't going to necessarily line up with that timing; and are there things that aren't necessarily tied to show needs, but we do want to advance and this would be the right timing to do that, for instance, the work in USD - of course, we're hearing about lots of studios, we’re trying to make significant advances in USD in our pipeline for Raya and the Last Dragon, which is our movie coming out next November - so that's not a show need, it's nothing out of the artistic vision of that movie that said we need USD, but it'll help advance a lot of future tools and workflows. And we need to find the right place to start feathering that in.
F: Which part do you like the most in the production of Frozen 2? Why?
EP: It’s a movie that has a lot of scope and scale to it. I like that it kind of takes you in more surprising directions. It takes you outside of what you've seen before in the first one, so it's not staying in the same zone, it's leaving Arendelle. It’s going out into the wild into a different environment and world, and it has sort of unique Spirits and settings that we haven't necessarily done before.
F: How did you achieve the scale of autumnal trees and foliage through technical changes?
EP: In a lot of our films, we have (been) trying to strike the balance between artistic stylization and procedural simulation to make sure we have the complexity and richness that we want, and yet still the stylization that we need. And we've worked overtime to build the tools to give that stylization for, say a single tree. And then you place them well to get a cluster of trees that looks nice. But now, when you have a whole forest that has a certain level of stylization to it, and it has a lot of depth to the ground cover, the pebbles and everything else around it as well. We needed to prove our toolset so that we would not only have that sort of balance of stylization and complexity on the single tree level, and then make a whole forest of them, we can stylize the appearance of the forest as well. So we had nested proceduralism which would allow us to build up, like here's a pebble, here's a cluster of pebbles, now here's a ground cover that includes some leaves and a cluster of pebbles; and then it includes a tree, and then there's a grove of trees, and then the grove of trees expands to the forest. And you can sort of stylize but also build up and populate at each of those levels. And then we created a tool called Droplet that was essentially a procedural painting tool that you could then paint down the trees in a more painterly fashion, so that you could have more direct control over the style and flow of the forest as a whole, and all the trees throughout it. So it did definitely lead to expanding on our Bonsai tree tools and our Aurora instancer, as well as developing the new tool like Droplet.
Bonsai Instancing Zootopia Test
F: What’s the challenging part of the production? How to solve it?
EP: I think there's a couple of areas environment side we had a very lush rich forest environment that includes very colorful diverse autumn forest, but also because its fall leaves are on the ground that also had to be very rich. On top of that when you start adding in the elemental spirits and you have something like Gale, the Wind Spirit, you're tying that environment as a character and having to make sure there's a lot of coordination between how the environment is built; and how the character of the wind plays through that, and then interacts with the rest of the environment, and with any characters and the scenes with Anna or Elsa or any of the other characters. So this film presented a lot of challenges with collaboration. A lot of things that like the Water Spirit and like the Gale that didn't fit neatly into one department, one group of people or a linear pipeline. So the challenge is finding the ways to iterate smoothly when you're having to have a very tight connection between people across departments.
I think we always start with the sort of research into trying to ground the challenge that we're looking at, and what the closest connection is to the physical world. When you have the Water Spirit taking the form of a horse, you study water, you study horses, and then you bring all the people across departments together, and everywhere from art and trying to understand the stylization, and how far you want to go in wateriness versus sort of solidity. The effects departments, the spray and the foam of the mane and the tail to the animators, so you really have everyone working together to look at the challenges together, form more of a team around the problems you're trying to solve.
F: What did you do to make these characters realistic?
EP: There is the realism you want, the realism of a horse movement or the realism of water movement. And where do those conflict, and how do you find the right balance between those, and the choices you may make for a beautiful horse animation may not work when the mane and tail are refractive water that you can see through. Say, the mane goes in front of the face, it's not actually completely covering the face, you're kind of seeing through that. So that's again where what decision might be made in animation may need to be iterated on when you see a render. Because of the effects of the water on the character, so it's definitely a challenge to find just the right balance for that character.
F: In this process, what kinds of tests did you do to give the designers the idea?
EP: I think with all of the tests and with the Nokk as well, we did start with some hand-drawn tests. Even seeing once again the example of legs, and how much the leg should sort of splash away into water, and how much they could stay fairly solidified, was something that we tested with some hand-drawn tests first. And then you take that into animation, and then you would try to run little sort of various types of character tests, like a still test of the Nokk with just some head animation. That informed that we needed to take the water distortion and reduce it on the face. Because there were subtle movements, that distortion was making the rig harder and keep that just on the body. Then you would do a test on how much spray and spindrift should be in there. And you do a running test. So it's kind of you really work closely as a group and sort of run these tests to explore different aspects and keep the Directors in the loop for that time.
F: Could you explain more about the unified rendering?
EP: I think when we talk about unified rendering and looking forward, at a lot of places at Disney animation, we have a glViewport that we use for when we're viewing things in our various departments and getting previews as we're working, and then you do a final frame render that on a render farm and takes a significantly longer chunk of time. Sometimes those technical requirements require different paths and different pipelines. We would love to find paths where almost what you see is what you get, and so there's more of a continuum from the preview that you see, to the final frame. It's almost more of a transition from speed to quality over time, but it's less of a dichotomy.
F: Any suggestions for the audience when watching Frozen 2?
EP: The movie takes place three years after the original story. The movies made six years after the original one came out, so there's been a lot of tech technology advancements. And I hope people can see it in all the beautiful images that are on the screen. At the same time, we want to bring you back to the same characters that you love from the first film. And you'll see some nice additions, like of advancement. Olaf now has a permafrost covering so that he won't melt as it's getting into autumn. He's learned to read now, and all the characters have sort of progressed. Because there has been a time period that's passed in the film as well.
F: You have made so many great animation features, which one do you feel most proud of? Why?
EP: I love different aspects of all of them. I have a special connection to Zootopia to a certain degree because XGen was one of the first developing (tool), when I first started at the company way back. And it was a big sort of fur-based show, and there was a lot in there that connected with me. Returning to Wreck-it Ralph with Ralph Breaks the Internet, it's always fun to revisit a place that you've been to before. And even going all the way back to Bolt that had a certain painterly style to it. That was exploring sort of a looser look that was a very different look at that time.
Thank Mr. Ernest Petti again for accepting our interview. Keep up with Fox Renderfarm and follow us on social media platforms, more interesting and insightful content is waiting for you!
Special thanks to Dan Sarto from Animation World Network, Ian Failes from VFXVoice and Chang Wei-Chung from InCG Media.
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