The CGI achievements of Pixar

News Mark Pickavance 16 Feb 2010 - 13:21

Mark charts some of the groundbreaking moments in computer animation from Pixar's relatively short history...

These days most people don't consider the technology that goes into a CGI movie or advert. It's assumed that the computer does most of the work and those involved simply take the accolades.

But that thinking is naive, as computer graphics have evolved dramatically since the first CGI scenes were incorporated into movies and, in many ways, Pixar has always been at the bleeding edge of what was technically possible. To understand the development of Pixar's rendering technology (called Renderman, incidentally) let's go through some of their movies and explain the advancements that each contributed to each, making each production special.

Toy Story (1995)

The fact this could be made at all was probably the biggest innovation, but behind that was a very careful balancing act between the complexity of the images and animation, and actually getting the production completed within a reasonable timeframe.

To help do this, logic was applied to each scene so as to identify those portions of the image that would require re-rendering between frames. So, if Woody, for example, was standing in front of a background that was largely unmodified by his movement, that was only rendered once and then retained as the animation sequence developed.

It's unfeasible not to acknowledge the importance of Toy Story in the history of CGI, as it was the point at which the impossible became possible. Unusually for the Academy of Motion Pictures, they actually noticed its significance, and awarded  the mastermind behind Pixar and the director of the movie, John Lasseter, a special Oscar in 1996 "for the development and inspired application of techniques that have made possible the first feature-length computer-animated film".

Toy Story proved that CGI could be used to tell a character-based story, and in doing so changed the world of animation forever.

A Bug's Life (1998)

This story of insect uprising marked a notable jump in the complexity of both character design and environment. Yet, this was still finely balanced with the demands on computer resources.

As such, much the same choices that drove the character design in Toy Story also lead them to choose hard exoskeleton bodied insects in this. But the extra computing power available did allow them a little 'soft body' extravagance with Heimlich the caterpillar.

In repeat viewing what's impressive about A Bug's Life are the simulations of natural vegetation and the sheer number of characters in some scenes.

See also: A Bug's Life - The Forgotten Pixar Movie

Toy Story 2 (1999)

Plenty of effort went into making the script for this movie as good as the original, but it was also another significant technical leap.

In the original, not wanting to push the technology too far, Pixar limited the screen time of human characters. But in Toy Story 2 they're much more apparent, and required to do more acting.

But in technical terms, the highlight of this production was certainly the fabric handling routines that allowed Woody to be sewn up and repaired.

Monster's Inc. (2001)

For very obvious reasons, in Toy Story Pixar avoided hair. It eats vast amounts of computing cycles to calculate, move and render, but in Monster's Inc it finally bit the bullet on exploring that requirement.

And just to prove it'd mastered hair entirely, it made Sully - one of the two main characters - entirely covered in long fine fur. In the movie, it's required to be blown by the wind, be moved by hand and generally look real at all times.

The richness of the visuals in Monsters Inc is striking, as is the quality of movement and expression in the characters.

Finding Nemo (2003)

In a word, 'underwater'. Creating believable visuals for numerous types of ocean environment was the challenge Pixar had here, along with portraying the various states of the sea surface. But along with that challenge, it also simulated the movement of bubbles and characters caught in eddies and currents.

This is probably the production where Pixar could rely least on tricks to reduce rendering times, and by the very nature of the environment, most frames needed to be fully rendered.

The Incredibles (2004)

The visual styling of this movie hides a significant change in the capability of Pixar's CGI technology. Where in previous productions notable limitations funnelled the look into particular directions, here design was king and the technology bent to achieve that.

It also has some huge external scenes on the island, dwarfing any CGI sets that it'd previously considered. But these were just the tip of a whole CGI iceberg of problems that the complexity of The Incredibles represented.

It's Pixar's first film that has an entirely human cast, using long flowing hair and realistic folding and tearing fabrics, among a long list of firsts.

Cars (2006)

For once the mechanics of a Pixar film didn't include creatures or people, but mechanical objects with suspension and friction with the ground. As such, these came with their own problems, not least designing them to move believably.

But with 1,000 times the computing power of the systems that rendered Toy Story, Pixar did have some scope for calculating more complex interactions between objects, and also handling reflections and imperfections.

The surfacing of the cars is amazing as it's built up from successive layers of gloss paint, nicks and scratches and then further degraded with dust and other damage. The scenes in the various race meetings also have more characters seen in a single shot than any Pixar production before or since.

Ratatouille (2007)

This film entirely moved the quality of 3D imagery up a notch from previous productions, both in the intricacy of what was represented but also in the range of situations that they chose to represent.

On seeing it for the first time, I couldn't help but be impressed with the sequences where the rat ends up in water and then emerges with wet fur. But lots of other special software technology was designed for this specific film.

The one that is repeatedly mentioned by Pixar is that it developed special procedural routines allowing one model to cut or slice another. Therefore, when a vegetable gets cut in the kitchen, the software handles the division of one model by another, and the animator can concentrate on telling the story, not organising exponentially increasing pieces of zucchini.

WALL·E (2008)

Technically, WALL·E built on the texture work done in Cars to better represent environmental decay, like rust and general wear and tear. The world in WALL·E is just one big refuse dump, and WALL-E is just one tiny trash compactor.

But the biggest achievement of this movie is to present a mechanical object as having a personality, something for which those who animated WALL·E should be genuinely proud.

Other notable achievements in WALL·E are the subtle atmospherics, lighting and the emulation of the 70mm camera traits typical of Super Panavision 70 shot science fiction movies of the 60s.

See also: Interview with supervising animator Angus MacLane

Up (2009)

Never resting on its laurels, Up is yet another technical triumph for Pixar. To give an idea of the extents to which they went making Up, there are 20,622 individual balloons supporting Carl's house when it first becomes airborne.

The physics of the house and its contents play a big part in the story and, as such, great efforts were made to make it move believably.

It was also the first Pixar feature in 3D, using Disney Digital 3-D, which brought with it additional problems regarding textures and scene design that previous 2D productions never encountered.

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