Issue link: https://digital.copcomm.com/i/83694
■ ■ ■ ■ Stop-Motion Animation Making Headway Each character starts as a pencil design on paper, followed by interpretations drawn in Photo shop. Once the artists and directors narrow the choices, modelers create clay ma- quettes in key poses for each character, and the armature department begins working on the tiny skeletons with ball and socket joints that will fi t inside the bodies. Th e heads and faces for ParaNorman's characters took two shapes. One, used for the zombies and some background characters, had silicon fl esh with a mechanism inside, a tradi- tional method of creating facial expressions, al- beit with new, softer silicon over foam latex for tic buy-off , the dense ZBrush mesh moved into PixelMachine SRL's TopoGun software, where modelers redrew it with a lower-reso- lution topology. "We produce each face thousands and thousands of times," McLean says. "If the to- pology is too dense or the fi le size too great, we can't produce very many parts at one time. 3D printing is a new art form; there's no es- tablished workfl ow. Our rigging supervisor, Michael Laubach, had to fi gure out how to produce high-level detail with low fi le sizes." At this point, a character's CG head is still a complete shell; there are no removable parts yet. Th e shell moves in two directions—to two diff erent groups working with Maya on the inside and outside of the characters' heads. For the outside, a CG modeler creates face masks. For the inside, a CG modeler designs and engineers the elabo- rate mechanical system. For Norman, it had 78 parts that animators could set in motion to move his eyes, eyelids, and "We build the faces in kits," McLean ex- plains. "One series of faces in a kit might allow Norman to say any line of dialog with a smile. With another kit, he could say any line of dia- log with a frown. We create each of his emo- tions with phonemes to build a foundation for the whole fi lm." Making Faces To build the kits, Laubach rigs the CG charac- ters in Maya. Th e rigs give animators the abili- ty to do poses and create each character's range of facial expressions, as they would with any CG character. Th e diff erence is that Laubach must be cognizant of printing limitations. "We print physical objects, so there are real-world limitations," McLean says. A lip stretched too thin might break when printed, for example. by moving control points predetermined by the rig, working from dialog samples and 2D drawings that provide a blueprint for each CG animators shape the facial expressions added fl exibility and longevity. Th e second technique, used for the main characters, employed the use of rapid-prototyping machines to print face parts. Much as they would if they were creat- ing a CG character for a fi lm, the artists be- gan the process by scanning the head of the clay maquette. "We captured tool marks in the clay, facets, everything that made the clay sculpt handmade," McLean says. CG model- ers created the rough topology from the scan in Maya, moved the result into ZBrush to exaggerate the details, and sent the fi le to the printer for a test run. "Th e printer softens edges, grooves, and val- leys," McLean says. "We needed to see what to push in terms of color and texture. We would never want to show the directors the ZBrush model or a rendering of that fi le because it's so exaggerated." Once the printed head received an artis- 34 August/September 2012 Digital skies and set extensions helped set builders add details and open Norman's world beyond the tabletop. ears. Some parts are printed plastic. Others are tiny metal bolts and screws. "People often think we're printing whole faces and eyes," McLean says. "But we build heads to be transformers." Norman's face is a mask held in place by magnets, as are all the characters' faces that use this system. When an animator removes the face mask, Norman's eyeballs are still inside the shell of his head. Animators move his eyes using the internal mechanical system. Th ey close his eyelids and move a blade of his hair with an X-Acto blade. Once moved, the parts stay in place until the animator moves them again. On the outside, eight thousand faces com- posed of snap-together eyebrows, foreheads, mouths, and cheeks give Norman his facial expressions. His buddy Neil has 3,000. character's range of expressions and phonemes. "Th ey'll take a line of dialog from Norman with a good range, for example, and use that to build his kits," McLean says. "Th ey digitally sculpt his faces. Th e diffi cult part is making sure each shape is unique and will be used in the fi lm. Th ey have to be as economical and considerate of printing as possible." Before a stop-motion animator puts a Nor- man puppet into a set, he or she builds expres- sions for the shot using the CG face kit. "Th e animator will sit with a facial animation spe- cialist," McLean says, "someone who knows every face. Th ey listen to the dialog together and create a playblast with the digital faces." Animators typically move the bodies on "ones" and faces on "twos." Th at is, they posi- tion the body in a unique pose 24 times per