Issue link: https://digital.copcomm.com/i/110536
n n n n CG I /Stereo 3D for non-cartoony characters���except for those in the Shrek films. Reisig asked for a change. ���I said that we had to get rid of the old, stilted Shrek rig,��� Reisig says. ���We had to have a more flexible rig. The old one was too puppetlike, and it was causing problems with the animators. So on the legacy characters, we tried to keep the basis of the classic rig and retrofit a new system. For the new characters, we used all the newest methods we had.��� The task of retrofitting the newer types of controls onto the classic rigs and fitting the new characters with new rigs fell to a group of character technical directors led by J.J. Jay and Andy Kao. ���We wanted to allow animators to get a broader range of acting, so we started with the existing rigs and folded in the newer controls,��� Jay says. ���The technical challenge was to allow the animators to do the things they are used to doing now without changing the look of the characters as they deform.��� Animators working with the new characters, and new versions of the old characters, though, used RIG, the new system. ���One of the advantages of having a homegrown tool is that we can take a [rigging] concept and do what we want with it,��� Jay says. ���For example, we use our elastic cage deformation quite a bit as a lower-level part of our deformation.��� This was key in animating Puss In Boots, who becomes a fat cat in Shrek���s alternate reality. A fat cat that sometimes walks upright on two legs, and sometimes gets down on all fours. When Puss changed from biped to quadruped, his hips and shoulders changed, and his belly had to move appropriately. The portly Puss also had to deform properly���and automatically���when the animators positioned the character in what Jay calls ���interesting poses.��� (DreamWorks is submitting a SIGGRAPH sketch on the techniques the TDs developed to move Puss���s plump body.) ���We played around with keeping the elastic cage the same distance from the joints that drive it, which gave us fake volume preservation,��� Jay says. ���We had to do some layering and localized blending, but [the rig] provided nice shapes right out of the box, and it allowed the animators to see the deformed body. There was no simulation; it was all animator-controlled. They didn���t have to rely on a downstream department.��� The flexible RIG extended into character design, as well; the TDs used the system to reshape a generic character into a variety of individual characters. ���Sometimes the art department drew variations and we tried to hit them,��� Jay says. ���Sometimes we needed help from the modeling department. But the TD 12 May 2010 department did most of the variations.��� To create more than 16 types of ogres, the riggers started with a default body and individual rigs for each of the four ogre families. ���Once we get the rig working with the default model, we can use the animation controls to create variations,��� Jay says. ���We can go a certain percentage in any direction with the rig and it behaves well. The deformation allows us to create pleasing shapes by varying the body and the face. Then we lock in the controls.��� In addition to providing sculpting controls for character variations and preserving Puss���s pudgy volume, the rigs also moved most of the characters��� hair and fur automatically. Consider says. ���Putting that into the rig would have impacted its performance.��� Total Effects When we first see Fiona, she stands atop a hill. She pulls off her helmet and her luxurious, long, red hair blows in the wind. ���Her wavy, flowing red hair is an integral part of her character,��� says visual effects supervisor Doug Cooper. ���Our character effects supervisor, Oliver Finkelde, started with the long hair system for Shrek 3, looked at the tools in Maya and Syflex, and put several pieces together to develop a new hair system for the film.��� In addition to updating the rigs and de- TDs retrofitted new controls onto the classic rig used for many of the legacy characters in Shrek, like Shrek and Donkey (top), but to move the now-pudgy Puss In Boots (bottom), they applied a newer and more flexible system aptly named RIG. a character that shakes its head, for example. ���The animator would focus on the head movement and then initiate a simulation pass,��� Jay says. ���The system would execute their animation and modify the values for the guide hairs. When the animator looks at the shot after simulation, the hair is moving on its own.��� If the animators didn���t like what they saw, they could change simulation controls or hand animate the motion by moving the guide hairs. In Shrek���s alternate reality, though, Fiona���s long hair required a separate simulation by the character effects team. ���It���s wild, and it falls over her shoulders in front and behind,��� Jay veloping a new hair system for Fiona���s locks, Cooper points to new setups for multiple-layered clothing, a magical ���poof,��� and a worldchanging event as interesting technical challenges on this film. For the clothing, the character effects team developed a system that could simulate multiple layers of clothing at the same time. ���Before, we had done multiple passes with one layer becoming rigid for the next layer���s simulation,��� Cooper says, ���but the look wasn���t believable, especially when you had a thin under-layer pushing around leather on top. 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