An article from Animation World Magazine about the animation techniques used in Wall-E.
Life is nothing but imperfection and the computer likes perfection, so we spent probably 90% of our time putting in all of the imperfections, whether it's in the design of something or just the unconscious stuff. How the camera lens works in [a real] housing is never perfect, and we tried to put those imperfections [into the virtual camera] so that everything looks like you're in familiar [live-action] territory.