Introduction to Character Rigging

Introduction to Character Rigging

Setting Up IK Solvers

 

Autodesk 3ds Max Tutorials > Character Animation Tutorials > Character Animation without Biped > Introduction to Character Rigging > 

Creating a Bone Structure

This lesson gets you started with bones by showing how to create them for a simple character. Bones are special objects that are ideal for a character rig. Bones are automatically linked as you create them, and can be shaped to resemble an actual bone structure for a character's skeleton.

A series of linked bones is called a chain. Two or more chains linked or connected together forms a hierarchy of bones.

Bones appear in viewports as ordinary objects, but they have special properties. Essentially, a bone is a visual representation of a pivot point, a direction, and a length. The bone points from its pivot point (the start of the joint). Its length is defined by the distance between the bones, and it points in the direction of the next child on the chain.

It is possible to set up unusual relationships between bones, such as a bone that does not extend all the way to the next child on the chain. However, the most common uses for bones observe the properties described above.

You'll start this tutorial by creating bones for a simple character. You can find the files for this tutorial in the \tutorials\character_animation\intro_to_rigging folder.

Prepare the character:

1. Open the file tut_introrig_start.max.

   

   This file contains a simple character named Pluggo. The character has one leg, a torso and a head, but no arms.

   TipThe character is standing on the construction plane. This positioning makes it easier to place bones and other character rigging controls, and easier to animate the character when the rig is complete.
2. Press the H key to open the Select Objects dialog and see a list of objects in the scene.

   The scene contains three objects: the character body, and two eyes.

   When rigging a character, you can make the process easier by:

   • Making a selection set for the character mesh so you can easily select it while working.
   • Making the character see-through so you can see where you are placing the bones.
   • Freezing the mesh to prevent you from accidentally selecting it while working with the bones.
3. On the Select Objects dialog, click All, then Select.
4. In the Named Selection Sets entry area, enter the name Pluggo Mesh, and press Enter.
5. Press Alt+X to make the character see-through.
6. Right-click any viewport, and choose Freeze Selection from the quad menu.

Create the leg and foot skeleton:

1. In the Left viewport, zoom in on the character's leg.

   This is where you will work for now.

2. From the Animation menu, select Bone Tools.

   The Bone Tools dialog appears.

   

   The Bone Tools floater provides functions for creating and editing bones.

3. In the Bone Editing Tools rollout > Bone Tools group, turn on Create Bones.

   When creating the bones, don't be too concerned about exact placement. You will get a chance to reposition the bones in the next procedure.

4. Create the leg bones using the character mesh as a reference. Click once at the hip, then click, in sequence, the knee, the ankle joint, the ball of the foot, and the tip of the toes.

   

5. Right-click to complete your bone chain.

   This creates a fifth, small bone at the end of the toes.

6. Right-click again to turn off bone creation.
   NoteYou can also turn off Create Bones in the Bone Tools dialog.
7. In the Front viewport, check the bone placement to make sure the entire bone structure sits inside the character's leg. If the bones are not inside the leg in the Front viewport, move the topmost bone to move the entire structure.

   Next, you will name the bones. It is a common practice to name the bones according to the joints where they begin, such as hip, knee and ankle.

8. Go to the Modify panel. Starting from the hip, rename the bones to: BoneHip, BoneKnee, BoneAnkle, BoneToe, and BoneToeTip.

Adjust the bone positions:

When placing bones for a character, it is more important to have the joints (pivot points) at the correct locations than it is to have the bones going through the mesh. For this character, the calf bows backward slightly, which makes it impossible to place the calf bone so it passes through the leg. You will simply position the bones so the pivots are in the right locations.

Also, positioning the bones with a slightly bent knee will help with a later procedure where you set up IK controls for the leg.

1. On the Bone Tools dialog, turn on Bone Edit Mode.

   In Bone Edit mode, you can change the lengths of bones and their positions relative to one another. This mode can be used both before and after assigning an IK chain to the bone structure.

2. Select a bone and move it.

   Notice that adjusting a bone visually alters the length of the bone before it. However, it is actually adjusting the pivot placement of the selected bone.

3. Continue moving bones until they are positioned similarly to the previous illustration.
   WarningTo change the sizes of bones, always use Bone Edit Mode rather than the Scale transform. Scaling bones with the Scale transform can cause bones to react unpredictably during animation.
4. Turn off Bone Edit Mode when you have finished.

Create the spine bones:

With a character rig, it is usually desirable to keep each limb as a separate linked chain. In other words, you would have a chain for each arm and leg and another for the torso, but you would not link these chains to one another with Select and Link. Instead, you would use rigging controls to tie it all together.

The next step is to create a series of bones for the spine and head. It seems logical to begin creating the spine bones at the top of the hip bone. However, if you do so, the first spine bone will automatically link to the hip bone.

To get around this situation, you will create the spine bones away from the character's body, then move them into place.

1. On the Bone Tools dialog, click Create Bones.
2. In the Left viewport, start creating the character's spine bones to the right of the character mesh. Create two bones for the spine and one for the head, then right-click to end bone creation.

   

3. In the Left viewport, move the lowest spine bone so it sits just above the leg bone.
4. On the Bone Tools dialog, turn on Bone Edit Mode. Adjust the bones so they follow the center of the character's body as closely as possible. Turn off Bone Edit Mode when you have finished placing the bones.

   

5. Starting from the lowest spine bone, name the bones BoneSpine01, BoneSpine02, BoneHead, and BoneHeadTip.

Create fins for the bones:

You can create fins, or extrusions, on the bones. Later, when you add controls and animate the character, your work will be easier if you can hide the mesh and work with the bones alone. Fins will cause the bones to approximate the volume of the character's body, which will help you effectively animate the bones without having to display the mesh.

1. Select BoneHip, the hip bone.
2. On the Bone Tools dialog, expand the Fin Adjustment Tools rollout.
3. Turn on Side Fins, Front Fin, and Back Fin.
4. Adjust the Size parameter for each fin until the hip bone fills out about 3/4 of the mesh. Check your work in the Left and Front viewports.

   

5. Create fins for the remaining bones in the skeleton as needed to make them fill about 3/4 of the mesh. Some bones might need only a back fin or side fins, while others might not need any fins at all to fill up 3/4 of the mesh.

   

Make a named selection set for the bones:

1. Select all the bones.
2. In the Named Selection Set entry area, enter the name Pluggo Bones.
   TipYou should always include the character's name in the selection set name, rather than naming the selection set just “Bones” or “Mesh.” If you add more characters to the scene, you will know which selection set belongs to which character.
3. Save the scene with the filename my_introrig_bones.max.

   You can find a scene with the correct bone placement and names in the file tut_introrig_bones.max.

   To learn more about creating and editing bones, see the Creating and Editing Character Bones tutorial.