Skeletons

Joints and bones

It is very important to first make a plan of the movements of your character before you start creating it. If you know what movements your creature is supposed to be able to do you can create the skeleton according to this and you will not have to go through the trouble of adjusting the skeleton after it has it's control curves and/or binding to the skin. You will also not have to deal with the inconvenience of having joints that you don't really need. So first make a list of the movements your character will make and sketch on a picture of your character where the geometry needs to bend, because that's where your joints will need to be.

Joints and bones covers:

• Creating a skeleton
• Editing a skeleton
• Parenting and hypergraph

Rigging

There are two ways of controlling the movement of your character: Inverse Kinematics and Forward Kinematics. They work in a different way, so in some cases it's easiest to use the one, in other cases the other and sometimes you will need a combination of both.

Forward Kinematics is a way of animating in which you rotate the joints themselves one by one to create the desired movement. It moves the character from the top of the hierarchy down. Example: for walking you rotate the joints one by one to get the desired position. This method is very precise and you have complete control over the movement of your character, but when you are animating you will have to key all the joints separately.

In Inverse Kinematics you determine the end position of a controller to create the desired movement. It acts in the other direction then Forward Kinematics, so it moves the joint from the bottom of the hierarchy up. Example: for walking you determine the end position of the foot and the rest will follow automatically. This method id quick and easy to animate because you only need to key the end position, but you don't have that much control over the exact movement because you only control the end position.

So before you start rigging, first go back to the list and the sketch of the movements of your character again. Now determine what will be the easiest way of animating the movement of your character. If you're not exactly sure of the right method you can first apply inverse kinematics, then check if you are, by only using this, able to make all the movements you want. If not, add forward kinematics.

Important!! Check before you start rigging that:

• the skeleton fits the character
• the hierarchy of the skeleton is correct
• the skeleton is placed at the origin of the scene
• maybe most important, your joints are oriented correctly (skeleton > orient joint)

Rigging for Inverse Kinematics

Rigging for Inverse Kinematics covers:

• Inverse Kinematics for a leg
• Inverse Kinematics for an arm

Rigging for Forward Kinematics

Rigging for Forward Kinematics covers:

• Forward Kinematics for a leg
• Forward Kinematics for an arm

Combining Inverse and Forward Kinematics

Combining Inverse and Forward Kinematics covers:

• Creating an IK/FK switch
• Creating a group based reverse foot
• The auto forearm twist

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