In other words, 250 out of 612 animated shots were totally CG for the scenes inside the colorful Easter factory -- a confectious nod to Willy Wonka.
"It's a bit of a departure for us," admits Raymond Chen, Rhythm & Hues'  visual effects supervisor. "When you create a full CG frame, there is actually no anchor for you, but you have creative freedom, which is both good and bad. If you don't get the decisions done at the right time, you can run into the problem of changes coming very late in the game, which we had to deal with.
Creatively, the biggest challenge was the design of the factory, which was ongoing past principal photography. Aesthetically, they went for a cave-like design with rock candy styrations, but that looked too much like a dirty bunker. So they made it more clean and hygienic in keeping with the making of candy. Then they settled on more of a grand cathedral design. However, there was also the problem of scale. Realistically, a factory for rabbits and chicks would be small in scale, but since the climax hinges on a former human slacker named Fred (played by James Marsden) coming to the rescue, they had to alter the size to accommodate him. Yet the machinery still had to be used by the small animals in this 150-foot-high factory, so that stayed fairly close to the ground.
"The factory sequences were complex with machinery and effects. Tim and [producer] Chris [Meledandri] wanted to give a sense of how the candy is actually made. That necessitated having all kinds of background characters making and transporting candy. From a character animation standpoint, we had to juggle other components of the factory setting. Technically, it made it more challenging and definitely stretched our pipeline to the max."
For rendering the environments, they had a choice of their proprietary Wren or Side Effects' V Mantra . After much testing, they decided it would be faster and better to go with V Mantra. However, for character rendering they used Wren to along with their home grown Voodoo animation software package.
"We were using PBR (physically-based rendering), which can be very computationally expensive, so our biggest concern in starting this was render time," Chen adds. "So we had to work out the technical solutions and educate our artists to work in very efficient manners to get the final images out. By the end, we worked it out to achieve multiple iterations."
Overall, the rabbits were straightforward, including the ninja bunnies known as the Pink Berets. However, E.B.'s interaction with Fred was different from his interaction with his fellow CG buddies.
"A rabbit is more comfortable on all fours, but E.B., for the most part, is walking and talking and performing like a human, so the challenge is to make his performance look enough like an animal that's standing up on two legs and not a guy in a suit," remarks Andy Arnett, Rhythm & Hues' animation director. "The other challenge is to get the age appropriateness of the character. We wanted him to look like a teenager and not a little kid, which is tough when you're working with a character that's 22 inches tall and looks like a little kid. So it was important to have him standing and walking and behaving like a teenager. We still had moments where he would run on all fours or hop up onto a countertop, so we would switch back and forth. The hero characters also had extremely long feet like Bugs Bunny, so it was tricky maintaining their animal-like movement.
Then there was the whole drumming challenge, which is E.B.'s defining characteristic. "We had to figure out how to make that work with a rabbit so we did an early test and had a lot of fun with it," Arnett suggests. "We went over the top and it went over really well, but when it came time to do our first teaser, different ideas had developed from the test. It went from being like a little kid drumming to being more like a professional musician who was very cool and comfortable. So we had to come up with different styles of a rock drummer. That required digging up lots of reference and finding a groove for E.B. that we could apply to all these other scenes. We looked at Neil Peart from Rush. We also found a YouTube clip of a little kid drumming, so we took a lot from that piece of reference and incorporated it into the later sequences."
It's a far cry from Alvin, Yogi or Garfield.
Bill Desowitz is senior editor of AWN & VFXWorld.