Here's the basic workflow for building a 3D character. This applies to both games and film, although the amount of detail is generally much higher in film characters.

Modeling
The first step is to create a static 3D model of the character, sort of like a little statue that can't move. A modeler friend of mine, Joe Bowers, built the Sarah model here. The Sarah model started out as a low-resolution polygon cylinder the size of the torso. Sculpting it into shape consists of pulling polygon extrusions like clay, adding loops of edges (with a free Maya add-on called MJPolyTools), and moving vertices around a whole bunch. Actually, a great trick is to only model the left half of the character and let Maya mirror your work to the other side. Sarah weighs in at around 5,000 polygons, which is a middle level of detail for a game character.

Texturing
For the color details, you can wrap a texture map around the model like a decal, or paint it directly in 3D. In this case, I started with reference photos of Sarah which I unwrapped and stitched together in Photoshop. It looks a bit like a rubber mask that's flattened out. It's amazing how much time goes into preparing the model for texturing—the process of laying out the UV coordinates can take many hours to get right.

Rigging
Next, we build a skeleton inside the model—kind of like the armature inside a stop-motion puppet. This skeleton determines how flexible the character will be and usually mimics human joint placement. You'll then build controls that make posing the skeleton easier. For example, inverse kinematic handles prevent the feet going through the ground when the hips move.

Skinning
To finish developing the character, the "meat" of the model is attached, or skinned, to the bones. This is where you determine which bones the polygonal vertices are stuck to. For example, you don't want Sarah's eye sockets moving when she raises her foot.

Animating
Now the character rig is ready for animation. The most important thing to realize here is that the computer doesn't do the animating for you. Just like the stick-figure flipbooks we did in the margins of our notebooks as kids, you've got to pose the character rig by hand for each key frame of the animation. Maya can fill in some of the blanks, but the best animation is touched by human hands at nearly every step of the way.

If you're animating for a game, say a first-person shooter, you'll create a lot of small snippets of animation that the game engine can string together or cycle. Things like a crouching walk, a run, a huge death animation, and so on. (Actually a lot of death animations are being handled by rag-doll physics now, just because it gets boring seeing the same canned death cycle over and over. But the really compelling work is still done by hand.)

In feature animation, visual effects, and game cinematics, you're not worried about building a library of animated cycles. Instead, you animate the full performance of the scene, playing to a single camera.

Of course, there are a zillion extra details, deformations and effects added to a production rig in order to deal with facial animation, squash and stretch, cloth, and hair and so on, but this is the fundamental workflow of developing a character in Maya. If you're interested in getting started with Maya, check out my book, Understanding 3D Animation Using Maya. It explains the fundamentals of building 3D characters, props, and sets, is packed with tutorials, and comes with a free copy of Maya Personal Learning Edition for you to use on your Mac or PC. You can also head to my site for a sample tutorial and more info: www.understandingmaya.com.

Want to learn more? Head over to page 2 for an excerpt from Understanding 3D Animation Using Maya that explains how to create depth of field effects.

Rendering – Depth of Field
Typically, one of your goals in rendering will be to mimic the look of film shot through a still or motion picture camera. By default, Maya’s renderer operates a bit like a perfect camera in a vacuum – there are no flaws. This sounds great, but it’s nothing like what audiences are used to seeing. Introducing flaws and optical phenomena to the Maya camera can go a long way toward mimicking realism. Depth of field is one such technique.

In a real-world film camera, in order to get a good exposure, you may need to increase the amount of available light hitting the negative. This is done by opening up the aperture. (Note: The camera’s aperture is measured by a setting known as an f-stop; low f-stop numbers are equal to wide apertures.) As this aperture is increased, the camera’s ability to keep a deep focus is decreased. So, while you may have focused on a subject in the middle distance, the background and foreground will go out of focus. This effect is called “depth of field.”

Depth of field can be used to great effect. It makes your 3D scenes look more like they were photographed with a film camera. Also, you can use a change in depth of field to focus the audience’s attention on a different subject without even moving your camera.

Rendering Exercise – Depth of Field

1. Set your project to understanding_maya\Chapter03\rendering_dof.

2. Open the scene rendering_dof_begin.ma.

3. In the scene you will see the airplane sitting in the barn. In the foreground is a sphere and in the background, a cylinder. Activate the Camera1 view panel (the active panel has a thicker border around it). Now click the Render current frame button on the shelf.

4. In the Render View window you’ll see an in-focus render of the plane as in Figure 3.96. Such an infinite focus is definitely possible in the real world if there’s lots of available light, but it sure isn’t very dramatic, is it?

Figure 3.96: Render without depth of field

5. Let’s look at some of the measurements in the scene (see Figure 3.97). If you look at the Perspective 1 view, you’ll see that some distance measurement tools have been created between the camera and the three subjects. (This is found under Create > Measure Tools > Distance Tool.)

Figure 3.97: Measuring distance from camera

6. Select the cameraShape1 object. In the Attribute Editor, turn on the Depth of Field checkbox.

7. Next, set the camera’s aperture to a small number, such as an F Stop of 4. Remember, a small aperture equals a narrow depth of field. (Unlike a real film camera, Maya’s cameras won’t actually adjust the amount of incoming light when the f-stop is changed, so don’t worry that you’ll change the apparent brightness of your scene.)

8. The Focus Distance can be set to equal the camera’s distance from the pursuitPlane, which the distance tool reports as about 12.7 units. This will produce a depth of field effect where only the plane is in focus. Render your scene (see Figure 3.98 and Color Plate X).

Figure 3.98: Focus distance of 12.7 units

9. Try setting the Focus Distance to 10.6 for an in-focus sphere as in Figure 3.99, and then try 17.9 for the in-focus cylinder as in Figure 3.100.

Figure 3.99: Focus distance of 10.6 units

Figure 3.100: Focus distance of 17.9 units

10. You may also want to experiment with different F Stop values from 1 to 64, in order to see the change in focal depth. This value can also be animated for a “rack focus” effect. This technique is often used to guide the viewer’s eye from one subject to another without moving the camera.

Excerpted from Understanding 3D Animation Using Maya by John Edgar Park
Copyright 2005 Springer Science+Business Media, Inc.