Joint Placement?

Chillo

Hi, I've been modeling characters for years but I still can't get correct join placement on my models. How many models should the typical humanoid model have, and where should they be placed? What directions can each joint move in? My biggest problem is mostly the shoulder and waist area. I think the concept of limbs branching off of a torso is escaping me. Can anyone give me advice? Thanks.

Emil Mujanovic

Moved this to Technical Talk.

Rick Stirling

I've been doing this a few years, creating skeletons for generic models and for specific actors based on mocap, and there are a few things I subscribe to:

CG bones are not bones, they are a simple deformation system. Don't try emulate the human body with its curved spine and the offcenter leg, just keep nice straight bone chains.

Place the joints as close to possible in the center of the body and limb mass - don't run the spine up the back of the model because that will bite you when the character bends forward.



For a general human I have 1 clavicle, 2 arm joints, 1 hand, 2 leg joints, 1 foot 1 toe (per side obviously), root (don't skin to this), pelvis, 3-4 spine joints, 1-2 neck joints, head.

I supplement these bones with roll/twist bones in the upper arms, forearms and thighs. Occasionally I'll have a calf roll.

The clavicles are a very important bone that control the lifting of the arm.

What directions can each joint move in? Stand up and stretch your body!

Mark Dygert

In addition to what Rick said, when placing bones it helps to think about what kind of envelope it will create. Depending on the software you're using you could get different kinds of envelopes, but in general its a capsule shape that runs along the longest part of the bone. This capsule is the base for the skin weights it can be very beatifically to have it create a solid set of envelopes.

I also add twist bones in the forearm(2) and upper arm(1), I skip adding twists to the legs, our characters don't do that much crazy leg movement, but if they did, I would add a calf and thigh twist. Skin to the twists but animate the regular bones. The twists are just deform helpers they shouldn't be animated.

What software package are you using? There are more then likely half a dozen scripts and workflow tweaks for Max and Maya along with pre-done rigs.