In Hop, teenage rabbit E.B. laments his impending crowning as the new Easter Bunny and instead makes way for Hollywood. Director Tim Hill called on Rhythm & Hues to realize E.B. and the film’s other anthropomorphized animals as CG creations. We talk to vfx supe Ray Chen and animation director Andy Arnett from the R&H team.

Designing rabbits

Hop’s characters began as illustrated designs by Peter de Sève. Rhythm drew upon the illustrations to create animals that were both more realistic yet still stylized. “We started with a number of concept paintings,” says Rhythm & Hues visual effects supervisor Ray Chen. “From that we got approvals from the director and worked on digital macquettes, then moved onto getting the characters to be fully furred and groomed.”

The film’s story follows E.B. (voiced by Russell Brand) as he leaves his easter egg factory home – and destiny – on Easter Island for the sights and sounds of Los Angeles. Here he meets out-of-work Fred (James Marsden), who ultimately helps E.B. with the rabbit’s long-time dream of becoming a drummer. The two worlds of E.B.’s existence meant that Rythm & Hues had to place the character suitably into the film.

“The first thing we had to work out for E.B. were the proportions we were going to use,” explains Rhythm’s animation director Andy Arnett. “We went with a rabbit that was about 21 inches tall when he stands up. When he’s walking around on two feet, he’s a little bit more like a human, which is kind of what we did with Alvin and Garfield. We had to work out how he was going to look and how he was going to carry his weight, and what the best way was to make an animal character give a human performance, as opposed to just a human that’s been put into a rabbit suit.”

Artists also had to tackle E.B.’s long rabbit ears – & those of his father, the current Easter Bunny, voiced by Hugh Laurie

Artists also had to tackle E.B.’s long rabbit ears – and those of his father, the current Easter Bunny (voiced by Hugh Laurie) – to establish which poses worked best to maintain character and personality while still having the animal be quickly identifiable as a rabbit. “The concept art we kept referring back to had E.B.’s ears swept back from his head,” says Arnett, “so that was the basis of the posing for most of his looks. But we found in a lot of situations if he was being shot from the front that it was hard to see his ears if they were swept back, and he started to look like a different animal. So we had to strike a difference between the concept art of the swept back look and still having him read as a rabbit quickly and easily from any and every angle.”

Stuffies and bean bags

E.B.’s venture into Hollywood required significant amounts of interaction with live action actors and objects. For these scenes, Rhythm utilized its now well-established on-set surveying and HDRI capture system. Production animation supervisor Chris Bailey would also often puppeteer ‘stuffies’ of the character in principal photography to help establish the timing and feeling of the shots. “The stuffie passes were great,” remarks Chen, “not just for reference of how big the characters were going to be and the lighting, but really also as a first pass of the performance.” In other scenes, the actors would hold black bean bags to help give the right weight and feel, such as when Fred’s sister Sam (Kaley Cuoco) cradles E.B. believing him to be a stuffed toy.

Practical effects were also crucial to sell E.B.’s presence in the real world. In one scene, E.B. and Fred are lining up for a musical audition before David Hasslehoff, with E.B. hiding out in a backpack. “That was a combination of practical effects and CG,” says Chen. “We had the special FX department build a little rig inside the bag that had a radio controlled device that could move around as if the rabbit was inside. We also built part of the backpack as a CG object so that when EB turns around and puts his hands down, he could interact with the bag.”

Animating ears and everything else

Rhythm looked to reference of real rabbits mainly for scenes where E.B. and other characters drop down to all fours for running and jumping, as well as animalistic actions like scratching the backs of their ears. The studio built numerous rabbit facial controls into its proprietary Voodoo animation system, particularly to deal with the eyes and mouth shapes. “What we found with working with these big furry faces with big muzzles was that it’s pretty tricky to get expressions,” notes Arnett. “They have to be really carefully sculpted and controlled to get them to read quickly and easily. Also, delivering dialogue and getting that to read correctly took a lot of careful handling. Even small changes in the angle of the head could affect readability of the lip sync, and the expression you were trying to get.”

E.B.’s muzzle had to be slightly tweaked to ensure it remained flexible for dialogue scenes. “One of the things that can happen with these faces,” says Arnett, “is that if you don’t put a lot of detail into the entire face, their mouths and cheeks can look kind of stiff. So it was important to us to be able to get a lot of flexibility in the face to make them feel alive and fleshy. We had a lot of help from ‘tech anim’, which is the department that comes immediately after animation. They will do things like secondary animation and cloth simulation and dynamics, wind blowing through fur, or compression of skin or fur up against a surface. We relied on them to add things like secondary motion to the cheeks, such as a little jiggle if the character was moving around. It really helped to make the character feel alive and breathing. One of the things we added, for example, was a sniffing motion, to give more of an animal feel to it.”

“Ears can be tricky things to animate – they’re like tails, … just a long FK chain – we had IK and FK available to us & could switch back and forth”

Andy Arnett
Animation Director R&H

Animation of E.B.’s ears was also important for performance. Although some harmonics were built into the ear movement, animators could keyframe at any time. “Ears can be tricky things to animate – they’re kind of like tails,” says Arnett. “They’re just a long FK chain – we had IK and FK available to us and could switch back and forth. We actually thought of the ears as almost being another pair of arms and we had to constantly pay attention to how they were moving, and so ended up using them as accents for emotions or punctuating dialogue.”

The Easter chicks

Workers inside the easter egg factory are mainly yellow-feathered chicks, also CG creations by Rhythm & Hues, with Carlos and his pal Phil (both voiced by Hank Azaria) the two central players. Animators approached them somewhat differently than the rabbit characters. “They obviously had beaks instead of mouths,” notes Arnett. “So here the director’s main concern was not getting a beak movement that looked too much like a piece of rubber that was being stretched around. We had to limit the animation to the corners of the beak area, and move those up and down and in and out for smiles and frowns, but still be fairly minimal with it so it didn’t look like we were stretching the geometry too much. One of our animators had worked on Legend of the Guardians and had had similar beak challenges.”

On some occasions, artists pushed the rigid beak movement for Carlos, who has deep-seated aspirations to be the new Easter Bunny. “He had to deliver some lengthy and over-the-top rants,” says Arnett, “and he also had to shove some worms down his mouth. So we went a little more cartoony there.” Chick feathers were treated more like fuzzy fur, and animation performance incorporated quick bird-like movements just to retain hints of the animal. Rhythm also used crowd software Massive for large congregations of the birds in the easter egg factory.

Animation beats

A key aspect of E.B.’s character in Hop is his love of drumming. For Rhythm & Hues, this presented a challenge as to the best way to depict his musical ability.  “We did an early test,” explains Arnett, “with a still background and put E.B. behind a drum set for 30 seconds or so. The animator went pretty over the top and everyone liked it. But as the film progressed, the client thought that style made E.B. look a little too young, like a kid playing with a drum set for the first time. So we ended up making it somewhat more professional.”

That approach to the drumming also helped for a gag in which E.B. actually plays with real-life musical group Blind Boys of Alabama in a recording studio. Drumming scenes were generally filmed using a real drum set with the cymbals removed, and then added later in CG to match E.B.’s performance. Rhythm also projected the live action drums from the plate photography onto CG versions to add a little movement and vibration where necessary. Artists looked to reference of a professional drummer filmed specifically for the recording studio scene and a later one of him auditioning in front of David Hasslehoff for a talent show.

A film inside a film

On previous shows, Rhythm & Hues has generally had to incorporate its CG characters into live action backgrounds. For Hop, however, the studio also completed 250 mostly all-CG shots for the easter egg factory. “It’s almost like a little full CG film inside the big film,” notes Chen. “The biggest challenge there was actually designing the factory. It originally had more of an underground feel with roots and rocks before we settled on something that looked more cathedral-like.”

The factory includes egg-making machinery and a candy waterfall and river. “The waterfall was a physics based simulation,” says Chen. “When it was actually falling according to regular physics, the director thought it looked a little bit static – he wanted more splashing and changes in velocity in the streams.”

“The other main challenge was scale,” adds Chen. “It’s one of these problems when you have small characters and they’re in this factory that’s 150 feet high. During the course of all the live action filming we would find ways to cheat EB’s height – he goes on tables or chairs or ledges so he can fit into the frame with Fred. But once we got into the whole factory, it needed to be somewhere that Fred, who is taken there, could move around quite freely without looking like he was a giant within the space. A lot of that was careful design of camera angles and props.”

Production shot Fred’s factory scenes on a minimal greenscreen set with only a floor, columns and window shapes behind him. Rhythm then composited him into its CG environment, sometimes replacing set pieces, such as the boiling vat of egg dye which had been re-created on set, to suit the shots.

The factory environment also necessitated a ramping up of Rhythm’s camera department, since the scenes required a CG camera. “We would start with the storyboards and then had a previs team working in Maya to make rough geometry for the factory elements with rough cameras and characters and motions that we used as reference,” explains Arnett. “To begin the final animation, we would take the Maya camera information from the previs, import that into our Voodoo files for the scene, and then our camera department would take over and do a pass of the camera.”

“In some cases,” continues Arnett, “the camera motion was driven by the performance of the character. If the character had to run from one spot to another, or even if the camera was tracking just a walking character, in a lot of cases we’d let the animator drive that camera in a rough way. It would then be passed back to the camera department to polish off the cameras and back to animation again.”

For Arnett, the most challenging of the factory scenes was one in which E.B. must dodge the multiple blades of a chocolate bunny carver while at the same time caught in a straight jacket of gummy material. “There were three sets of four blades each,” he says. “At the start of the shot E.B. comes in at real time and then we switch to a slow motion effect, and then the blade chops off his whiskers, then it goes back to real time and he has to keep dodging the blades.”

“The shot was actually originally four seconds – 700 frames – longer than what is in the film. It also involved a lot of work on the side of tech anim and the effects department too, with the bits of chocolate getting chopped off almost like dust. We had one animator on that shot and they did such a great job, even if it was the one that probably caused us to lose the most sleep.”