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View Full Version : Why those tiny little extra-bones?



White Knight
02-10-2003, 12:30 AM
When I'm reading tutorials about bone/skelegon-setup, they mostly seem to make one small, extra bone along the Z-axis. They call it "controller-bone" or sumfin.

Some guys even make more of those little bones like one on the wrist and the ankle and so on.

Can someone explain to me what these bones are for?



/White Knight

SplineGod
02-10-2003, 02:10 AM
Sometimes little tiny bones can be added as additional hold bones.
They can be used as an extra rotational bone to help get rid of gimbal lock.
Several tiny bones can be used to help a mesh deform better by distributing the twisting across several bones.
Tiny bones can also be used as end effectors for IK Goals.
Basically that is what the goal attaches to in order to pull a limb around.
Tiny bones can also be used to "zero out" the root of a bone chain so that the rest of the bones are oriented properly.

Skonk
02-10-2003, 06:13 AM
Nice explanation larry :)

James.

Chazz
02-10-2003, 08:03 AM
Often times animators use extra little bones for controlling sections of the rig. A 'control' bone might not have any influence over any point in the model, but might drive the upper body, for example.

On a rig I'm doing right now, I'm using hip control bone that moves the legs from side to side as well as a master bone that all the other bones in the rig are attached to.

White Knight
02-12-2003, 05:14 AM
Thanks for the neat answers fellows! =o)

Yet I got to admit I'm still a bit confused and I'd like to see an illustrated (or even better - animated) tutorial demonstrating the funktions about the "extra-bones".

Chazz
02-12-2003, 08:37 AM
You should check out Timothy Albee's Character animation book...it's very well written and goes into detail about what you're asking. It answered a lot of my rigging questions and made the process really smooth.

SplineGod
02-12-2003, 01:59 PM
Originally posted by mfessenden
Often times animators use extra little bones for controlling sections of the rig. A 'control' bone might not have any influence over any point in the model, but might drive the upper body, for example.

On a rig I'm doing right now, I'm using hip control bone that moves the legs from side to side as well as a master bone that all the other bones in the rig are attached to.
Ive noticed that occassionally if I have inactive bones in a character that has weight maps that sometimes when the character is reloaded some of the geometry gets funky.
Instead of using the root bone to move a character around I have a Main Body Null that the body is parented to.
Like I said, usually those little bones in the wrist or ankles are used as the end of the IK chain (also called an end effector). This is what the IK goal object "grabs" so you can move that limb around.