SIGGRAPH Course: Character Setup: Rigging for Animation

by Jessica Fernandes
July 26, 2002

Fluid movements, subtle motions, and life behind a character are all made possible through rigging and made believable through animation. The day long course on character setup took attendees through a fast paced sampling of particular approaches to character rigging, rig setup, skin deformation and facial animation. Although much of what was said sounded vaguely familiar, if not very familiar, having the opportunity to pick out some minute tricks of the trade in the presentations, given by lecturers from Summer Breeze, Weta Digital Ltd., DreamWorks SKG and Blue Sky Studios, made it all worthwhile.

The course began on the right foot, pun intended, with a demonstration of feet rigging. An aspiring animation student, myself, I remember having once painstakingly followed instructions for creating a “reverse foot”. A similar, more visually intuitive method was shown here. This technique, presented in combination with humour, insight and instruction, will very likely be the choice approach for my next character rig.

After demonstrating how to rig fingers and establishing the importance of rotation order and animation symmetry, the presentation shifted to the actual rig layout. The concept stressed in this section was the importance of building everything in modular components. This enables greater flexibility when the need to rework a particular section arises.

Having worked with joint weighting and morph targets, it was interesting to learn about muscles, another means of skin deformation. The pros and cons of some of the other methods were explored, as well as in what instances a particular approach should be employed. The hypergraph structure of organization, for muscles, was then elaborated on. Finally, the use and advantages of scripting were advocated.

In the final portion of the course, one of the animators who worked on the feature film “Ice Age” spoke on facial animation. He explored the advantages of file referencing (where all files reference the same rig) and voiced the need for adequate communication between the modeling and rigging departments. The use of a version control system, where files have to be checked in and out, was suggested as a means of facilitating proper communication between different teams. Having explained a little about the animation basics behind Sid, the main character in "Ice Age", the speaker went on to describe mouth and eyelid animation for one of his personal projects.

Computer graphics can be breathtaking. Being able to take this one step further, through animation, is truly magical. With a well made rig, and an understanding of the subtleties that make a character believable, nearly anything is possible. Exploring the complexity underlying these CG characters, we come to understand how much goes into making character animation look so convincing.