Wednesday, 6 March 2013

The Technological Exploits Behind The Scenes Of Pixars Cars 2

Pixar, the hit-making studio which treads new technological ground with a majority of its films, launched Cars 2 a couple of years back. Real physics was applied in its earlier movies such as the escape of thousands of balloons in the movie Up or real lighting effects in the pitching and rolling of garbage cans in Toy Story 3. With Cars 2, Pixar once again pressed its computing powers to the core limit and has gone well beyond them. In this movie, the filmmakers pioneered several ways to handle common special effects.

Creating the special effects did not come cheap. As per the views of the supervising technical director, Apurva Shah, Pixar had to increase the scale and size of its render farm by three times so as to achieve the computing powers to create the novel effects necessary for the film. Some the most important effects and the technology behind them are explained as follows:

-Water Effects
With Finding Nemo, Pixar had invented a way to render softer-looking water. On the contrary, with Cars 2, the design team felt that the audience would expect the oil rig sequence in the movie to feature stormier, edgier water. To achieve that effect, they explored a new set of water systems and used a mathematical wave model Tessendorf, which Shah said allowed the creation of more sharper, cuspy sea waves.

In a film with cars as the central characters, and glamour and glitz are provided by the story lines, it would not work to cut resources for effects which would result in the cars not feeling real. Designing the shading and the reflections of the cars was a crucial component of the visual effects work. In the original Cars movie, Pixar had used the newest technology for reflections and shading. But, with Cars 2, the design artists came to possess new tools in their hands. One of the major steps was the ability to design the paint to make it look like having suspended metal flakes giving it sparkle and sheen.

-Gatling Gun Physics
Another part of the movie featured a scene in which a loud commotion takes place bullets, smoke, tracers, bullets colliding with objects, etc. In order to get it right, the team turned again to physics. The scene required some video game references. They created their own physics engine to sort out the dynamics. It involved multiple physics simulations simultaneously Volumetrics with the guns smoke, rigid body dynamics with the bullets flying from the gun and more.

One of the prime reasons behind Pixars ability to do its job is the powerful, giant render farm situated in its main headquarters. There is some serious computing power there and Cars 2 required about 12 hours on average to render each frame.

Some sequences were complexes those involving tracing of rays which involves simulating the hitting of light on surfaces. A large quantity of computational power was required to process these frames which took up to 80 to 90 hours to be rendered. The render farm has about 12,500 cores running on Dell render blades. Also, the network backbone, file servers and other pieces of the computing architecture were boosted in order to cater to the making of the movie.

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