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Saturday, October 27, 2012

A few skin rigging tips

Hi,

I thought some of these skin rig tips may be helpful.

Here's an example of a skin rig scene I made in (Maya 2008) that still is not quite complete but it uses some of these tips. I used the bendy tips on the neck and torso, and I used the straight line tips on the arms and legs.
(skinExample.ma 1 MB)

skin rig tips:
1. making a .ma file that can control a spine ik curves cvs and allow for lots of bending
(stickyNoHairFiveJoint.ma 78KB ) .
I used this file multiple times by importing it into skin rig scene and manually fitting it
so it could control a rigs spine ik. The surface of this I bounded to the deformation rig joints so deformation rig
moves surface. While the joints attached to the surface of this are to move the spine ik curve by binding them to the spine ik curve. The spine ik curves spine ik chain in turn was used as the geometry bind joints.

The technique I used basically uses pointOnSurface nodes to keep joints on the surface so when surface moves the joint move. Also it uses normal constraints to keep the joints rotation aiming okay when surface moves. A node based approach for keeping the aiming like Jamie McCarter's (jamiemccarter dot com) Constraining_to_a_Mesh_in_Maya may be a more robust approach.

2. similar to 1. but it tries to keep the spine ik curves to move in straight lines
(quickSkinControl.ma 78KB ).
Its installed similarly to 1. But it doesn't have a surface so instead of deformation rig moving surface deformation rig moves an end joint and a group of this (.ma). Then this has some other joints which will move the spine ik curve.

The technique I used here basically uses ik sc to keep the joints aimed okay. The aiming and parent constraints keep the center on same line as rest and gives this a straight line feel. I used set driven keys on distance nodes to keep even spacing of joints (by scaling root joints in down chain direction). Using ik sc joints for aiming rather than aim constraints i found easier to implement.


cheers,
Nate


Inspired by Matt Estela's (tokeru dot com) for wonderful examples on surface constraints.
Inspired by Jason Schleifer's Animator friendly rigging (jasonschleifer dot com) for learning about using ik-sc handles for aiming and spline ik stretching.
Inspired by Aaron Holly