Just wanted to put out some rigging rules ive learnt over the years. The biggest problems i see with rigs is actual usability, what they really want a character to do. So heres a set of rules ive formulated over the years mainly derived from anticz, but have kept me in good stead for 40 or so production rigs.

(taken from my site)

0. Torso control

1.Independant hip control, that doesnt affect the chest.

2.Independant chest/neck control that doesnt affect the heads orientation.

3.Independant head control, thats orientated to the root/torso control.

4.Shoulder controls that are orientated with the chest, but dont control the
orientation of the arms - allowing for shrugging.

5.IK/FK arms/legs with natural foot. This means if the controls move further
than the ik the legs naturally peels away (in ik mode)

6.Knee/elbow controls

7.Foot/toe control

8.Heel/Ball of foot left/roll

9.Ball of foot twist eg. stubbing out a cigerette.

10.Finger curl control & independant digit control

So the spine can be anything:fk/ik/splineIK as long as you have the ability to control the hip and chest independantly. A main Torso control controls both. The arms in FK, follow with the chest, but when you rotate shoulder keep there orientation to allow strugging.

The head is setup to allow that if you rotate the chest the head keeps its orientation, the neck follows with the chest. The head can both be rotated and moved. When moved the neck follows with it. The heads main orientation comes from the torso for overall control i.e rotating the torso rotates everything.

The knees and elbow are simple pole vectors, which can be parented control anyway you want. The foot should have both fk and auto contols: heel and toe and roll heel, roll ball of foot, twist at toe. Also peeling the foot from its controls should naturally curl, to allow smooth transition eg. jumping.

FK/IK in both legs and arms can be anyway you want. Ive reverted back to the old 3 bone chain blended method, with snapping: it just works.

Thats pretty much my basics, if built some crazier rigs, with full stretch, bend bone curve controls and these can all be built on top. The key is fast posing, and transparency of controls.

I posted this up at 10second too. This is by no means the 'definative' rules for characters ,but a good solid set than can be applied to quads, birds, infact pretty much anything. Controls can always be built on top, such as stretchyness, curviness, bendbond, eye lookat's a so on. The problem i had from animating has been gimbal and counter animation. Ive used these rules to build 40 or so rigs from ogres to humans, to rats and dragons and animate them also. It makes it very fast to pose and fun to use.

cheers,