Recruiting animators for Toy Story was brisk; the magnet for talent was not the pay, generally mediocre, but rather the allure of taking part in the first computer-animated feature.Lasseter said that on the challenges of the computer animation in the film "We had to make things look more organic. Every leaf and blade of grass had to be created. We had to give the world a sense of history. So the doors are banged up, the floors have scuffs." The film began with animated storyboards to guide the animators in developing the characters. 27 animators worked on the film, using 400 computer models to animate the characters. Each character was either created out of clay or was first modeled off of a computer-drawn diagram before reaching the computer animated design. Once the animators had a model, articulation and motion controls were coded; this would allow each character to move in a variety of ways, such as talking, walking, or jumping. Out of all the characters, Woody was the most complex, as he required 723 motion controls, including 212 for his face and 58 for his mouth. The first piece of animation, a 30-second test, was delivered to Disney in June 1992 when the company requested a sample of what the film would look like. Lasseter wanted to impress Disney with a number of things in the test that could not be done in traditional, hand-drawn animation, such as Woody's yellow plaid shirt with red stripes, the reflections in Buzz's helmet, the decals on his space suit, or venetian blind shadows falling across Andy's room.
Every shot in the film passed through the hands of eight different teams. The art department gave a shot its color scheme and general lighting. Under Craig Good, the layout department then placed the models in the shot, framed it by setting the location of the virtual camera, and programmed any camera motion. To make the medium feel as familiar as possible, they sought to stay within the limits of what might be done in a live-action film with real cameras, dollies, tripods, and cranes. Headed by directing animators Rich Quade and Ash Brannon, a shot went to the animation department from layout. Lasseter opted against Disney's approach of assigning an animator to work on a character throughout a film, but made certain exceptions in scenes where he felt acting was particularly critical. The animators used the Menv program to set each character into a desired pose. Once a sequence of hand-built poses (or "keyframes") was created, the software would build poses for the frames in-between. The animators studied videotapes of the actors for inspiration, and Lasseter rejected automatic lip-syncing. To sync the characters' mouths and facial expressions to the actors' voices, animators spent a week per 8 seconds of animation.
Afterward, the animators would compile the scenes, and develop a new storyboard with the computer animated characters. They then added shading, lighting, visual effects, and finally used 300 computer processors to render the film to its final design. Under Tom Porter, the shading team used RenderMan's shader language to create shader programs for each of a model's surfaces. A few surfaces in Toy Story came from real objects: a shader for the curtain fabric in Andy's room used a scan of actual cloth.Under Galyn Susman and Sharon Calahan, the lighting team orchestrated the final lighting of the shot after animation and shading. Each completed shot then went into rendering on a "render farm" of 117 Sun Microsystems computers that ran 24 hours a day. Finished animation emerged in a steady drip of around three minutes a week.Each frame took from 45 minutes up to 30 hours to render, depending on its complexity. In total, the film required 800,000 machine hours and 114,240 frames of animation.There are over 77 minutes of animation spread across 1,561 shots. A camera team, aided by David DiFrancesco, recorded the frames onto film stock. Toy Story was rendered at a mere 1,536 by 922 pixels, with each of those pixels corresponding to roughly a quarter inch of screen area on a typical cinema screen.During post-production, the film was sent to Skywalker Sound, where the sound effects were mixed with the music score