Character Setup Character Setup is the process of creating handles and controls for anything that a character animator will need to adjust in order to create performance. Generally this process involves creating a skeleton for each character model and attaching that skeleton to the character model. Some of the skill sets that make up a good character setup artist are sculpture, anatomy, animation, physic, and figure drawing.

Character Setup Character setup always occurs after modeling during the production pipeline. In many cases character riggers will work with a model and send it back to modeling in order to add detail to areas that will require more detailed deformation that what is currently available with the model geometry.

Character Setup In large production studios character setup is an extremely involved process that requires character riggers to create physically accurate muscle systems that deform in a realistic manner when the character model is animated. Character setup has become an extremely advanced field that is often overlooked when a casual observer watches computer animation. Character setup artist often work hand in hand with character animators in order to prepare the character rig for the exact type of motion the animator is looking for. Often times once an initial rigging pass is completed on a character, the rig is given to an animator to test and “break” the rig.

Skeletons A skeleton is an armature that is built separate from a model that drives motion of the model geometry. A skeleton is created and then attached to geometry using different process depending how the model needs to move or deform. A skeleton is set up in a hierarchy where joints are parented to joints further up the hierarchy.

Kinematics Kinematics are the mechanics of motion. In Computer Graphics kinematics describe the process which determines how a model moves during animation. During preproduction character setup artist work with the director and animators to determine the what type of kinematics system will be used to rig the character models based upon what is the desired motion

Forward Kinematics Forward Kinematics involves rotating and positioning each joint into position as you move down the hierarchy. The rotation of a joint affects the position of all the bones and joints that are beneath it in the hierarchy. FK is similar to the animation techniques used by traditional stop motion animators where each joint is positioned individually as you move from the center of the model out. For example you would move the shoulder before the upper arm, the upper arm before the forearm, the forearm before the hand and the hand before the fingers.

Inverse Kinematics Inverse Kinematics is the process of determining the joint angles and positions needed in order to create a desired pose. Instead of rotating each joint individually down the hierarchy, Inverse Kinematics allows the animator to position the end joint of a skeleton in one pose and the IK setup will determine all of the joint angles needed to create that pose. Setting up IK controls is an involved process that requires the character rigger to know which angle is the preferred angle of movement for a joint.

Bind Pose The Bind pose for a model is the position of both the geometry and the skeleton at the time when the skeleton is attached to the model. The most common bind pose is the standard “T” position where a characters is standing up straight with arms fully extended out and legs close together. In many cases the final use for the character rig will determine what bind pose will be most efficient. If a character model is will not be deforming a great deal, a more relaxed “arms down” pose might be a better bind pose. In Maya, the bind pose is the transform values of the skeleton and model at the time when you bound them.

Root Joint The root joint is the top joint in a skeleton system, every other joint in the skeleton is a child of the root joint. Generally for character animation the root joint is the pelvis. This will serve as the center of balance for the character. When the root joint is moved the entire skeleton and anything attached will move with it.

Parenting In some cases attaching geometry to the skeleton is as simple as parenting the geometry directly to the joints. This is generally used for simple characters or situations where geometry does not deform or bend like a simple robot character or mechanical hinge. Each piece of geometry is parented to it’s corresponding joint.

Skinning In most cases geometry has to be attached to a skeleton through a process called skinning. This process involves binding groups of vertices or CV’s to the skeleton allowing the geometry to deform based on movement of the underling skeleton or muscle system.

Rigid Bind Rigid binding is considered simpler that smooth binding because no control point is influenced by more that one joint. It is useful for creating defined hard creases. Rigid binds work great for anything that is non-deforming like hard surface models or mechanical objects.

Smooth Bind A smooth bind allows control point to be influenced by more that one joint creating smoother more organic deformations. A joint’s influence varies across a surface as the control points move farther away from the joint. The amount of influence joints have on a control point must be normalized. This means that all of the influences on a control point need to add up to 1. Rigid BindSmooth Bind

In Maya a smooth bind can be applied using Closest Joint or Closest Distance. Closest joint assigns control point to the nearest joint in the hierarchy. This is common when skinning characters because it pays attention to the skeleton hierarchy. Closest Distance assigns influence based on how far the the control point is from each joint. Maya also has gives the user controls over the maximum number of joints that can influence a control point and the rate at which influence drops off as a surface point moves farther away from each joint. Max Influences determines how many joints can influence 1 control point. This is important in determining how. A max influence of 1 can be thought of as a rigid bind. Drop off Rate determines how much a joint’s influence drops off as con

Painting Weights A smooth bind is usually editing with a process called painting skin weights which involves adjusting the amount of influence a joint has across a surface. Since skin weights must be normalized, when the influence of one joint is decreased the influence is transferred to other joints in the hierarchy that have influence of that control point or area This process takes time, but is required to refine way a surface deforms as it moves.