Maya: Inverse Kinematics
Simple Human Skeleton Walk Tutorial

arrows.GIF

          ik.gif

Draw the skeleton:

In the Rigging Module:
Select Skeleton->Create Joints
          1  In the front view click the first joint for the hip
          2  Click the hip bone straight across from the first point
          3  Switch to the side view click the knees, ankle and toe.
                    The knee should have a bend, the ankle should be above the ground.
                     It is important to position the bend, so the bone knows what axis to hinge.

           ik2.jpg             ik3.jpg

Press the up arrow on the keyboard three times until the entire leg (not hip) is highlighted.
Use Skeleton->Mirror Joint->option.jpg
          Choose YZ
          Click Mirror

Press the up arrow on the keyboard once until the entire skeleton is highlighted.
Create Joints for upper body: start by selecting hip joint.
          6  In the side view draw the middle of the back bone with a slight bend.
          7  In the side view draw the center of the shoulder blades.
          8  Switch to the front view and draw the shoulder straight across from the last joint.
          9  Switch to the side view and draw the elbow.
         10  Draw the wrist.

Press the up arrow on the keyboard twice until the entire arm is highlighted.
Use Skeleton->Mirror Joint

Press the up arrow on the keyboard once until the upper skeleton is highlighted.
         11  In the side view draw the neck and then the head with a slight bend.

           ik4.jpg                  ik5.jpg


Add handles to the legs and feet:

Use Skeleton->IK Handle Tool->option.jpg
          Choose Current solver Single-Chain Solver
          Click Close.
Click the right hip to start the handle
Click the right ankle to finish the first handle.
Do this again for the left leg. Use Y to start the tool over again. (This is a shortcut to remember any last command.)

Click the right ankle to start the foot handle.
Click the right toe to finish the handle.
Do this again for the left foot. Use Y to start the tool over again.


A little test:
Select the entire body from the hip, this will select the top group in the hierarchy, move the body around, notice the feet follow. OK put the body back to 0.


Set Keyframe 1 for the handles:

Set the playback end time on the time slider to 100.

Move the timeline over to frame 1 at the bottom of the screen.

Select the 4 handles, you may want to use Window->General Editors->
Hypergraph: Hierarchy
.

Highlight Translate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected.


Another little test:
Select the entire body from the hip only, Move the body around, notice the feet do not follow, they are stuck to the ground. OK put the body back to 0.


Set Keyframe 1 for the body:

Select the body or top node of the skeleton.

Highlight Translate X, Y, and Z and Rotate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected..



Set Keyframe 30 for the body and handles, foot up:

Move the timeline over to frame 30 at the bottom of the screen.


Select the body or top node of the skeleton.
Use the Move Tool to move the body forward in the Z axis being careful not to move the feet from the ground.
Use the Rotate Tool to tilt the body forward a bit in the X and Y axes.

Highlight Translate X, Y, and Z and Rotate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected.


Select 2 of the  handles for the right foot.
Use the Move Tool to position the leg and foot above the ground.
Select all 4 of the  handles for both feet.
          (You must set keyframes for both feet to avoid skating,)
Highlight Translate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected.

             ik6.jpg          ik7.jpg
             Keyframe 30                                            Keyframe 50

Set Keyframe 50 for the body and handles, foot down:

Move the timeline over to frame 50 at the bottom of the screen.


Select the body or top node of the skeleton.
Use the Move Tool to move the body forward in the Z axiws a bit.
Use the Rotate Tool to un-tilt the body back a bit in the X and Y axes.

Highlight Translate X, Y, and Z and Rotate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected.


Select 2 of the  handles for the right foot.
Use the Move Tool to position the leg and foot back on the ground.
Select all 4 of the  handles for both feet.
Highlight Translate X, Y, and Z in the channel box.
Use the right mouse key over the numeric input area, choose Key Selected.


Set Keyframe 80 with the same procedure as keyframe 30, except with the other foot.
          When you move the body forward it is OK if the foot rips out, this is the foot that will move forward.

Set Keyframe 100 with the same procedure as 50.



Arms:
Select the upper arm joint and use Rotate Z in the channel box to animate the arms swinging.



Skin:
Change the size of your joints to make skinning easier: Display->Animation->Joint Size

Select the surface to be used as skin and then shift to select the skeleton too.
Choose Skin->Bind Skin

Adjust the bind:
Select the skin you would like to fix, select Skin->Paint Skin Weights->option.jpg
Adjust the size of the brush, Stroke->Radius(U)
Select the joint you would like to paint
adjust the Value to 0 to erase or zero out

Select vertices and use Windows->General Editors->Component Editor Smooth Skins tab to manually skin, the weights should add up to 1