Ever wanted to know what it takes to work at Pixar? Well we have a special treat for you today! Jiayi Chong currently work at Pixar Animation studios on feature films. His work mainly involves developing physics simulation tools/engines for the studio. These include rigid body dynamics, deformable solids, cloth, hair, fluid dynamics and skin simulation tools. In his spare time, he also develops casual games on the iPhone / iPod / iPad touch platforms. He has worked on the movies Wall-E (2008), Up! (2009), Toy Story 3 (2010) and the new film Brave (2012). Read below for the full interview…
You seem to work for a company that many people only dream of; Pixar! Could you tell us a bit about the duties and responsibilities of a technical director?
Jiayi: I am a technical director in Pixar’s Global Technology Group. This is a group that works closely with the animators and artists in production of our feature films. We develop a set of tools and technology catering to the requirements of the film in order to achieve the desired look for the film. Some of the projects include designing a system to generate procedural vegetation that can cover large areas of virtual land and making bouncy toys that react to character/animator interaction in the digital realm. My day to day involves speaking to different groups and production(animators, artists etc.) about what their requirements for the film are and going about designing a system that will attempt to produce what they want in order for the movie to be made.
So would you consider yourself a generalist? Or do you have a specific skillset that you try to stick too?
Jiayi: At the core I consider myself a computer scientist who specializes in the field of computer graphics. We are the technical people with an artistic inclination to produce beautiful images and animation digitally. The difference of course is that we express such imagery via writing computer algorithms/code with mathematics as the fundamentals that drive such computer programs. A full length feature film is a very involved and complicated endeavor. If you are to observe the real world around you very carefully, you will notice that quite a lot of the simplest things in life like the light shining through a water droplet or the swaying of a simple leaf are actually quite complex and difficult to describe in simple terms. That is where the mathematics and science come into the picture. In order to model such phenomena accurately and beautifully on a computer, we harness the power of modern computing coupled with mathematical and physical models to produce a flaming torch or a tumbling backpack on screen. So the people I work with have not only have a rigorous background in computer science but also an eye for the aesthetics.
As the evolution of your films has progressed, from Toy Story, to Wall-E, and now Brave, what kind of technical advancements were available to you now in order to create more realistic simulations that weren’t afforded to you a few years ago?
Jiayi: We are at a very exciting time in the history of computing. The mobile processors today in your phone or tablet device rival those of personal computers just a few years ago. The desktop computers today are even more powerful with multi-core systems available at a reasonable price. This puts an amazing amount of computational power in our hands which we can put to good use. For example on Wall-E, we used finite elements to simulate the flesh on the human characters. Finite element analysis is a field traditionally used to model the amount of stress a bridge or airplane wing can withstand before breaking. These algorithms used to be in the domain of supercomputers but we are now running them on regular desktop machines to make movies! We also use such computing power to solve navier stokes equations; these are the equations used to describe the motion of fluids like smoke and water. This means we can model natural phenomena more easily and effectively with advances in processor speed and memory.
During simulations why are movements of characters confined to secondary motions? Do all beginning stages involve mandatory stationary positions?
Jiayi: The animators layout the major motions of the characters because that is how “acting” on the computer screen is done here. Secondary motion however is really hard for a human being to do because if you were to observe a person walking really closely, you will notice a ton of things happening at different levels. There is the hair flopping about, the belt swaying left and right, the cloth fluttering in the wind, the keys dangling off some handle etc. If you miss out on animating those secondary details, the result is a rather dull looking digital character. The human eye is really good at catching out such irregularities. However, it would be a huge monumental task for a human to actually animate all the wrinkles in the skin, cloth and dangling items! That is why we employ computer simulation to solve this particular thorny issue and make our character animations look compelling. So the animator goes in and animates the character’s major actions. After that, a simulation pass is run on the character to breathe even more life into it.
Is your team only involved with human characters or do you branch out and also work with dragons, monsters, etc.?
Jiayi: We do not just work only on humans. On Toy Story 3, computer simulation was used on almost all the toy characters including slinky dog’s spring. On Brave, we have computer simulation passes on many of the creatures in the film.
Your new film Brave opens in theaters soon. What was the best part about working on this film and what kind of shots did you work on?
Jiayi: My group developed a new skin simulation system for the creatures on Brave. That was a rather exciting thing because a lot of films do not actually simulate the skin of creatures as they move about and this takes away from the realism of it all . I was also involved in developing a simulation system to create the look of large rivers, torrents and lakes. Those were exciting and complicated shots to run. Some of the fluid shots took so much computing power that they ran for over a week. The river simulation system we wrote ran on 128 processors at once across a distributed network system. At any one time in the simulation, those machines were solving the equations of fluid flow and computing millions of positions of water surface particles. The usage of science and engineering in producing art is what is most exciting about this process.
Are you a fan of anime? Do you have any favorites or any that have inspired you?
Jiayi: I used to watch some anime, I confess I am not a huge anime geek. I am a bigger fan of the Chinese Wuxia novels and series, especially the ones from Jin Yong (Condor Hero series etc.) The characters and stories behind them are hugely inspirational for me.
How important is it to use references in your work?
Jiayi: I use a lot of BBC nature documentary footage for my references of creatures and natural phenomena. I think they are fantastic and reveal to me a lot of detail of the natural world. My recent favorite films are Monkey Eating Eagle of the Orinoco and White Falcon,White Wolf both from the BBC. The filming, composition and narratives are truly amazing.
Lastly, what advice do you have for someone looking to go down a similar path as you and someday land a dream job at Pixar?
Jiayi: If you are interested in doing something similar, I think one should focus heavily on math and physics since those are the foundations you will build on for computer graphics. At the same time, learn to code! I taught myself programming at 16 by picking up books in public libraries. Today with the internet, the resources are even more easily available. Read up on computer graphics literature, write your own 3D engine if you are motivated enough. Also, pay close attention to natural phenomena. Have the curiosity of a child (I still do) when observing something “simple”. Watch a balloon pop, then play it back in slow motion and notice of the minute, intricate and amazing details that are involved as the material shatters and breaks. It is all very exciting stuff and you do not need to submerged yourself in a fantasy world to do it. I often feel that magical things are all around us but most people just end up ignoring it!
Visit the official site for Pixar and their new film Brave: