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Maya Skeleton Setup (DOC)

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					                                     Maya Skeleton Setup

        Setting up a skeleton for your character and binding it to the skin.

This tutorial will go over creating a skeleton for your character and attaching it to the skeleton using the
bind command. We will also be discussing the options for each of the bind tools and the sub-tools that
allow you to perfect it. Some of you will be creating characters with two legs, four legs, no legs, etc. The
easiest way for me to go over all of this is with a basic human character.

First, when modeling your character, you want to be sure that you pose him in a “T” shape before you
even attempt to create a skeleton for it (See fig 1.). By doing this there will be fewer alterations when
binding and your CV’s will not get intertwined.




                                                   Fig 1.

Once your character is set up you can begin to build the skeleton. Before you start creating the skeleton
you want to setup the options for the joint tool. Go to Skeleton > Joint Tool  When the option box is
                                                                               .
open, set auto joint orient to none (Fig 2.).




                                                   Fig 2.



This setting makes sure that joints constrain properly when binding to the skin. Once this is
set we can begin creating the skeleton.
                                            Creating the Legs

Now we can begin the actual skeleton. Depending on what kind of character you have, your results will
vary. I usually start with one of the legs. Simply click once to start the skeleton, then click each time you
want to place a joint and at the completion press enter to finalize it.. See example below for my
character’s leg skeleton (Fig 3.).




                                                    Fig 3.

You will notice I did not use the reverse foot method like described in the “primitive man” tutorial in the
Learning Maya book. If you wish to use the reverse foot, refer to pages 314 – 320. The reverse foot has
you create a second bone structure, connect it to the foot, and add an attribute to control the foots roll. I
personally like to keep the skeleton rather simple, animate it, then once my walk is done, go back and
animate the foot’s roll by hand. You should do whichever you feel more comfortable with when creating
your skeleton. It is also a good idea to name all of your joints when you are done. This makes for easier
editing. Use the channel box to name your joints like we learned in earlier lessons.

Once you have your leg set up we will want to add an IK handle to it. An IK Handle is a manipulator
which makes animating the leg easier. Before we add the IK Handle though, we need to have the leg
have a slight bend in it so the handle knows how to control the leg. Simply select the knee joint and
rotate it a little to create a slight bend in the leg (Fig. 4).




                                                   Fig. 4.
Once the bend is completed you will need to set the preferred angle. Setting the preferred angle tells
Maya how to control the leg’s movement. In this case we are saying to bend at the knee. Select the
whole leg skeleton, then go to Skeleton > Set Preferred Angle. (Fig. 5)




                                                  Fig. 5.

Now that the angle is set, we are ready to add an IK Handle to the chain. Simply go to Skeleton > IK
Handle Tool. (Fig. 6) Then click on the top joint, then on the joint where you want to end the bending
(the ankle joint). Once that is done you will see a thin line going from the Hip joint to the Ankle joint.
This is what you will Use to control the animation of the entire leg. Select the handle and move it to see
how the leg reacts (Fig. 7).




                   Fig. 6.                                                   Fig. 7.
We now have an IK Handle set up on the leg and we are almost ready to animate with it. We just need
to rig it now. Before we go into rigging it we will just go over what and where a few things are. (Fig. 8)



                                                             The pole vector starts at the start joint, and with
                                                             the handle vector defines the reference plane.

                                                             Because moving the pole vector changes the
                                                             orientation of the reference plane, moving the pole
                                                             vector can also change the orientation of the joint
                                                             chain directly, just as manipulating the twist disc
                                                             can change the orientation of the joint chain. This
                                                             is because the joint chain's degree of orientation,
                                                             or twist, is defined as the difference in orientation
                                                             between the reference plane and the joint chain
                                                             plane.

                                                             The twist disc is located at the end joint. The twist
                                                             disc is a manipulator for twisting the joint chain by
                   Fig. 8.
                                                             rotating the joint chain plane.



The pole vector effects the skeletons rotation around a certain plain. At it’s default settings, the pole vector faces
forward and creates an invisible plain that it will rotate around. See figures 9 and 10 below for a better
explanation.




                   Fig. 9.                                                    Fig. 10.

 Fig. 5 above shows the IK Handle pulled up and              Fig. 6 shows the IK Handle moved above the
 the leg deforming properly. You can see it is               plane of the pole vector. Once it moves above
 almost at the plane of the pole vector.                     the pole vector the leg is flipped and not
                                                             properly aligned.
What we want to do is change the direction the pole vector is in which will allow the leg to rotate freely
and unchanged. To do this, select the IK handle and press the show manipulator button (Keyboard
shortcut T). (Fig. 11.) Then move the pole vector so it is pointing inwards facing the body’s center (Fig.
12.).




                   Fig. 11.                                                  Fig. 12.

Now the rotation plane is going perpendicular through the leg. So now when we move the IK handle to
rotate the leg we will have no undesirable changes. The only problem is now the leg is facing inward and
kind of pigeon toed. This is where the twist disc comes into play. While the manipulator is showing, use
your left mouse button and click and drag to rotate the twist disc so the leg is facing forward (Fig. 13).




                                                  Fig. 13.

Notice how the Pole Vector is now facing inwards. Now if we grab the IK handle and move it, the leg will rotate
properly with no negative effect on the skeleton. (Fig. 14 – 15)




                   Fig. 14.                                                  Fig. 15.

Now that the pole vector is going perpendicular through the skeleton, it will allow it to rotate a full 360 degrees
without and deformations or tweaking as compared to before when it was facing forwards.

				
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