Many new characters were created for the third installment, and the ten-year-old models from the first Shrek were rebuilt. Shrek, Fiona, Donkey, and any character from the first film needed a complete upgrade while maintaining the familiarity of the first film’s characters. Shrek and Fiona were also required to don the garb of royalty, including high heels and a cinched waist, something the original models were not prepared to handle.
Taking the opportunity to include subtle improvements, Modesto and Cutler added additional resolution to the case used for the muscles and face to improve the control of the skin over the eyes and between the brows. They also increased the muscle resolution on the face in order to add more control to the mouth and eyebrows, and added details like the folding bags of skin over the eyes, sliding skin over the jaw area, and dimples.
For Merlin, the decision was to simulate one strand running the length of the beard. The beard needed to collide with the chest and also his simulated garment, layering simulation on simulation. Merlin is simulated head to toe, and the beard setup had to handle multiple collisions. The beard is actually the collision surface for the clothing, but if the animators needed to reverse that, the character effects department could re-tweak the simulation.
“Basically we took a layered approach, where the first layer was running a simulation that did in fact collide with the body, but it didn’t take into account the face,” explained Cutler. “Since it was just one strand, it was difficult to get a full collision with the chest. We couldn’t really represent areas like the sides of the beard since we were only simulating one strand.” By adding a second step, applying a deformation cage onto the beard, it took into account the collisions on the chest and some of the interactions of the face. That started integrating the facial animation into the final look of the beard. The third step was taking each individual hair of the beard and sort of gluing it onto the deformation cage they created.
Rebuilding the Shrek cast models for greater movement, DreamWorks also has a hair-do.
CGSociety Production Focus
By Renee Dunlop
n ‘Shrek The Third’, many of the biggest advancements
will go unnoticed to all but the trained eye, but the
trained eye will be impressed. VFX Supervisor Philippe
Gluckman, Character TD Supervisors Lucia Modesto and Larry Cutler, and Matt Baer, Head of Effects, covers the latest adventures at DreamWorks Animation.
When you see the film, look for attention to detail in the facial animation and hair setups, the wide range of character silhouettes and crowd scenes, expanded movement and interaction with the clothing, subtle camera movements to mimic a hand held camera, Global Illumination throughout, improved fire, and for the first time, animated feet and high heels.
“We have far more variety in our hairstyles, and what we are tackling is much harder to do because of characters with longer hair,” said Gluckman. “Particularly Sleeping Beauty, with her long flowing hair, and Merlin’s beard.” Sleeping Beauty’s hair appears soft and healthy, moving with her and dynamically parting around her shoulder collisions. Her hair is designed so that when the guide hairs start to diverge at a certain angle- such as hair separating at the shoulder- it needs to part into two different clumps. DreamWorks Animation had to come up with rules that caused all the fine interpolated hairs to recognize the obstacle, working to get just the right parameters for realistic friction. Not enough friction caused the hair to glide too easily against the shoulder, and too little made it appear to stick.
Both Sleeping Beauty and Merlin have long hair, but are quite different in terms of the challenges. Sleeping Beauty had hundreds of hairs that had to interact with her shoulders, yet the animators needed to art direct the behavior on a shot by shot basis. But for Merlin, the goal was to keep the beard from splitting apart and instead to move as a unit while maintaining a light, airy feel.
Merlin has a full-length beard that almost goes to the floor. DreamWorks’ R&D Department developed a new hair simulator specifically designed for longer and curlier hair. The in-house software is called Rigid Rod, a rigid body dynamics with Feather Stone constraints, and was used on Merlin, Rapunzel, with Sleeping Beauty.
Merlin’s beard has kinks and curls, but does have a clumped look. The trick was to get the individual hairs to have a little bit of separation and movement, especially in the face area, but at the same time to maintain the fact that this beard was designed to maintain it’s shape and not to split apart at a macro level. That was the challenge, to really get some breakup of the beard and the feel that each hair had its own motion. But at the same time, you see the same silhouette regardless of the pose. “We were concerned because of the length of the beard and that it’s so much a part of Merlin’s face, even more than typical hair,” explained Cutler. “The beard also partially covers his face, so we had to make sure you could still see the expressions that Merlin was emoting.”
