Pixar is demonstrating the next step in the evolution of crowd animation at SIGGRAPH 2022


Throughout the history of animation, there have been a number of challenges that animators and artists have had to overcome. One of the biggest hurdles? crowds. Typically in the background of scenes, the advent of computer animation has greatly aided this effort as the story demands it.

I immediately think of the Walt Disney Animation Studios classic from 1996, The Hunchback of Notre Dame, where hundreds if not thousands of background characters appear during the Festival of Fools sequence. Using computers to animate these for the first time in a Walt Disney Animation studio, they appear as hand-drawn 2D characters, but have a very limited range of motion compared to the film’s stars, really just raising their arms over and over again Head.

That was in 1996. Phenomenal progress for that time. Fast forward a few years to 1998 The Life of a Beetle by Pixar Animation Studios. Fresh from the innovative and commercial success of the first full-length computer-animated feature film, toy story, The studio team worked on this larger-than-life view of the world through the eyes of insects…namely, an ant colony. As told in the documentary The Pixar Storyone of the greatThe biggest challenge the studio faced in producing the film was crowd animation.

Darla Anderson, producer, said in the documentary about life of a beetle, “So the producer goes to John (Lasseter) and says, ‘John, we technically can’t do a mass shoot with more than 50 ants in it, so can you frame the film around that limitation? He said: “I’m willing to accept that if that’s all you can do, but I think you can do better.” So he helped put this crowd team together…they ended up becoming the heroes of the movie.”

The Life of a Beetle used finite state machines in the studio’s puppet (or menv) software at the time and has come a long way since then. Although the technique of The Life of a Beetle was sustained Cars, A new simulated crowd (where calculation is done frame by frame and order is very important) has been adopted for the massive crowd of rats Ratatouille, with 100-10,000 agents in a crowd.

This technique was maintained cars 2. It was Brave That was the first to adopt the new proprietary software developed by Pixar itself and named after the previous nickname WALL-E, “Presto.”

Only used by Pixar Animation Studios, Presto pushed their original puppet software out the door. Though the software is again proprietary, Pixar said it was designed to be intuitive and familiar to animators who have traditional cel animation experience. Using their own software also allows changing the code of that software depending on the needs of a particular project, e.g. B. Crowds!

Back then, Presto used a kinematic method (crowds that can be scrubbed around, computed history free, fast, scalable, and tractable) called the Crowd Placement Editor, which worked well for up to 1,000 agents.

The good dinosaur had flocks of birds far exceeding that limit, and Find Dory also pushed the limits of what their software can do, so they had to branch out and use a simulated method in a program called Houdini using specially developed crowd software called MURE. This method allowed between 100 and 100,000 agents.

That brings us to today, where Pixar introduced the Presto Crowds Foundations tool into its cannon and developed a new (and incredibly fast) system built right into its software’s engine that aggregated models (called “crowd primitives”) Delivery uses artists and animators with directly manipulable masses while maintaining proceduralism for bulk edits. PCF can also generate up to tens of thousands of agents with near total control.

At SIGGRAPH 2022 we could see this new system being put to the test at a crucial moment To redden, in a high point during 4*Town’s headlining concert, which took place towards the end of the film. A boy band concert held in the early 2000s would surely attract a concert of tens of thousands of people. Known for its high level of detail and authenticity when telling a story, Pixar knew it had to involve a crowd of this size.

The scene hosts many of the film’s technological triumphs, including a crowd of this magnitude reacting and reacting not only to the film’s hit boy band, but also to a giant red panda that appeared at the concert.

Tools in the system can now give animators the ability to move the crowd with ease. Simple rigs can now show where the animators should move, how they should react, and how dynamic they should be. Various packages embedded in the programming give artists the ability to automatically populate numerous characters with various individual attributes, ranging from height, weight, clothing, and more.

Crowd characters can also be pre-animated with different motion sets and added to a library for artists to choose from when animating their scene. The original mass animation of the Giant Ming Panda that arrived at this concert reportedly showed the crowd too scared to the point where the actual audience was too scared for that particular moment in the film. So the artists went back to their presets and found some lower intensity panic moves pulled from the mass animation in both Continue and Incredible 2. The note came so late in the game that with the help of the new system, the scene only took about a day of work to change.

However, the studio concedes that even with this big leap, there’s still room for improvement. They still want to work on de-intersection, flocking, secondary movement and collision avoidance. Pixar still has a lot in the pipeline (we already know about it elemental), and as is usual in the studio, while art drives technology, technology will surely inspire the art to come.

To redden and other Pixar Animation Studios films are streaming now Disney+.


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