Rigging basics

Rigging

In this worksheet we are going to cover the fundamental concepts of manually rigging a character.

We will cover creating a skeleton and forward kinematic controller.

Open Maya and set up workspace

Open Maya and make a new scene
In the top right of the screen, change the menu set to Rigging.

Import the model

Import the snowman model from Blackboard by going to File > Import

Create a Skeleton

Enter the front view by tapping the space bar, hovering over the front view, and tapping space again.

Turn on X-ray joints and X-ray shader in the Shader panel menu item.

Turn on snap to projected center on the top menu bar.

Adding spine joints

Open the Rigging tab

Select the Create Joint button

Click on the centre of the bottom of the Snowman to add your first joint, this is the root joint.

Click to add more joints at the waist, chest,neck and the top of the head.

In the Outliner, open up all the joints by pressing the + symbol
Rename all the joints by double clicking on them, this is really important and will help you later.

Add arm joints

Select spine_2 in the outliner, and with the joint tool selected add joints to the right shoulder and hand. You may want to turn off grid snap to place them more acurately.

Rename the right shoulder joint and the right hand joint in the Outliner.
The joint chain in your Outliner should now look like this:

Check yours carefully, if it doesn't look right you can move joints around in the outliner by middle mouse clicking and dragging on them.
If you cannot fix it, you can just delete the bad joints and make them again.

Mirror the arm

Our model is symetrical so we can mirror the right arm across.
Select right_shoulder in the outliner and select the option box next to Skeleton > Mirror joints

Change the options to mirror across the YZ axis and replace right_ with left_ (assuming you named your joint correctly before)
Press apply and you should have a left arm

Check the perspective view

Go back into the perspective view (HINT:tap the space bar)
Turn on x-ray joints (HINT: shading > x-ray joints)
Orbit around the snowman to check that all the joints look like they are in the centre of the snowman and its arms.
If they are not you can select individual joints in the Outliner, and then press w to move them. This will move the entire joint chain, if you just want to move one joint press d

Tidy up skeleton

The last thing that is important to do is reset the rotation or all the joints.

Select all the joints in the outliner by clicking the root and shift clicking the last one.

In the top menu, choose Modify > Freeze Transformations

Select just the root controller and press the options button next to Skeleton > Orient joints

Make sure your settings match these

Press Apply.

Add controllers

To make the skeleton easier to animate we add controllers.

Open the curves tab

Create a circle

Scale the circle up so it is larger than the base of the snowman

Create 2 more circles, move and scale them so they sit around the waist joint and the neck joint.
Create 2 more circles, rotate, scale and move them so they sit around the shoulder joints

Rename circles in the outliner

Select all the circles and freeze the transformations by going to the top menu item Modify > Freeze Transformations

Rearange the controllers by clicking and dragging with the middle mouse button parent them together correctly. This will ensure that when you move the waist or root controller, the nested controllers will move as well.

Constrain the joints to the controllers

Now that we have all the joints and controllers created, we can bind them together so that the controllers control the joints.

Constrain the root

We want the root controller to control position and rotation of the entire skeleton.

In the outliner, select the root controllers and ctrl + click the root joint so both are selected ( it is important you do it in this order)

Select the option box next to the top menu item Constrain > Parent

Make sure the Maintain offset box is ticked

If you now move or rotate the root controller, the whole skeleton will move. If you try this make sure you reset the position back to its original position before you continue.

Constrain the orientation

For the other joints we are just going to use the controllers to control the orientation.

Select the waist controller and the spine joint using ctrl + click.

Select the options box next to Constrain > orient

Make sure the Maintain offset box is ticked

Select Apply

Now you can do the same thing for the other 3 controllers.

Constrain the orientation of the left_arm_controller to the left shoulder joint, the right_arm_controller to the right shoulder joint and the neck controller to the neck joint.

You can now controll the entire skeleton by just using the controllers.

For this example we will just create these few, but I hope you can see that on a more complex skeleton we could create many more controller ( fingers, legs etc)

Skinning

Now we get to the best bit, we attach the skeleton to the mesh in a proccess call Skinning

Select the Body object and the root joint

In the top menu, select the options box for Skin > Bind skin

Depending on the shape of the character you are rigging, you may want to experiment with these options for the best result.

Start by Changing the bind method to Closest distance

Then press Apply

The skeleton will now be bound to the character.

Rotate the waist and arm controllers to see how the character reacts.

You may notice that when you rotate the arms down, the body and face are effected.

When Maya binds the mesh to the skeleton, it uses the bind method to determine which areas of the mesh are influenced by each joint.

We can experiment with different bind methods to try to improve the result.

Unbind

We can unbind the skin and try again.

First undo until the snowman is back at their original position.
With the snowman selected, go to the top menu and choose Skin > Unbind Skin

We can now re bind the skin with a different method.

Select the root joint and the snowman again and In the top menu, select the options box for Skin > Bind skin

This time select a different binding method, I found that Heat map worked best in this situation, but feel free to experiment.

You can now test you rig again by rotating the controllers. It doesn't need to be perfect but you want to get it as good as you can. In the next worksheet I will show you how we can refine the binding using weight painting.

But for now, we will move on.

Eyes and Hat

You may have noticed that the hat and eyes don't stick to the head.

Make sure the head is back in the correct place.
Select the neck_controller then hold ctrl and select the hat (doing it in this order is important).

In the top menu, now select the small box next to Constrain > parent

Check that the box that says "maintain offset" is ticked
Press apply
You can now do the same for the eyes, one at a time, parenting them to the neck controller.

If you now rotate the neck controller, the eyes and hat should stick to the head.

You could use the same method to parent objects to the snowmans hand.

Finished Rig

We have now created a functional rig for a character, the controllers can now be keyframed to animate.

Challenge

Create a simple animation with your snowman character. Make it