Using 275 animators, PDI spent five years animating every frame of the story. Out of that work sprung the foundation for the film, which appeals to all age groups.
Animation is a team sport.
Once that was completed, casting began for all of the characters. It's delightful not just to kids but to teenagers and adults. Another challenge posed to the animators was trying to come up with animated human characters that looked believable. Other challenges involved animating scenes where Shrek bathes in mud and animating fire. To get a realistic look for Shrek's mud bath, animators had to resort to live-action.