As simply put rigging is the process of giving a computer generated asset the ability to move. Whenever a person not in our industry asks me what do I do I generally start with this. Then of course, you can go on to imitate puppets and puppeteers with your hands.
Now not so simply put, rigging is the process of building a system to be used by an animator to deform a CG asset in a very specific manner. This deformation takes place on multiple layers, providing all the needed controls for hitting shapes and poses designed in the pre-production stage.
Okay, let’s deconstruct this.
When I say “deform a CG asset” I mean the ability to translate, rotate, scale or make it squash, stretch, bend, etc. Generally the base of a character rig is it’s bone structure which allows for moving the limbs and body in a way similar to how we move in the real world. That is why researching and studying anatomy is very important for riggers who want to improve.
The piece about the “very specific manner” is in regards to being able to build different types of FK or IK chains, IK/FK blends, blendshapes, etc. The keyword here is specific, because every aspect of a rig needs to come from a need. Every choice in the process of rigging is to always be bound by a good reason for achieving a specific result. Otherwise, we are shooting in the dark trying to hit a moving target. Therefore, it is very important for a production team to be able to communicate exactly what they expect and want to get in the end. Because, if we add a module to a rig “just in case” we are bloating the rig, and please let’s not bloat our rigs.
The “multiply layers” bit refers to the ability of deforming objects in different, but again very specific ways, and then sequencing them in a chain to produce the final result. The face is the classical example of this, where in most rigs people tend to use a combination of a few local rigs – rigs built to deform only in local space and then add them via a blendshape to the world space rig.
Then “providing all the needed controls” is again crucial for keeping the rig as light and clear as you possibly can. In our day to day lives we are very much used to clutter everything we interact with – bedrooms, kitchens, your home folder, etc. But again, when rigging an asset we should be thinking as minimalists. Which is to say, only add controls or functions if they are going to add value to the rig. Also, it is very important to make sure the shapes of the control objects makes sense, so the animators can now instantly what they are about to pick.
And lastly, the part about “hitting the shapes and poses”. Now there are a couple of metrics that describe how good or bad a rig is. Ones that I have mentioned above are functionality, performance and clarity. But in the end of the day, rigging is just a part of the animation pipeline. Therefore, as always we need to have a clear reference point to keep us on the right track. Take a look at modelers and animators, they always have their reference opened up on the side to help them stay consistent. Why would rigging be any different? We should not be thinking that we can rigs that are absolutely perfect for our purposes, without having a clear idea of what those purposes are.
Therefore, making sure that we can get the shapes and expressions that we have received in the character sheets or animatic, or even our own sketches in a more casual production, is not only making it easier for the animator, but it is making it possible to realize the initial concept.