Building Emotion: The Basics of the Eyes, From Sybex | 3 | WebReference

Building Emotion: The Basics of the Eyes, From Sybex | 3

Building Emotion: The Basics of the Eyes, From Sybex

Rigging the Lower Lids

You may have noticed that in the two previous sliders, up and down have an effect as well as left to right. For our Ctrl_Lids slider, the up and down movements control the upper lids and the left to right motions control the lower lids.

Select the plane named LwrLids and type in the expression:

LwrLids.translateY = -Ctrl_Lids.translateX / 5

This merely links LwrLids to the left and right motion of that same slider used for the upper lids; don't miss the minus sign! Moving the Ctrl_Lids slider up, down, left, and right can create all sorts of combinations for the eyelids (Figure 7.13).

Figure 7.13: Different slider positions yield interesting expressions.


Rigging the Brows

As with all the other pieces, we'll need to create a control for the brows. Duplicate the original Ctrl_Prnt hierarchy again and rename the new circle Ctrl_Brows.

Select the brows' parent object Brows and enter the following expression:

Brows.translateY = Ctrl_Brows.translateY / 15

That will make the eyebrows move up and down. Now, we need to fake some emotion. I've talked a lot about what is and is not right on a human face, but this is decidedly not very human. For this face, and an introduction to the interface style and practice, I'm going to go with some more classic cartoony poses. Select LBrow and add the following expression:

LBrow.rotateZ = Ctrl_Brows.translateX * 10

And to the right brow add the same, but with a minus sign in front of the expression, so that the right brow does the opposite:

RBrow.rotateZ = -Ctrl_Brows.translateX * 10

What that added, effectively, was the ability to set sad and mad poses like those in Figure 7.14.

Figure 7.14: The brows' control in different positions can create most anything you might need on such a simple character.


Re-Rigging the Mouth

To fit in with our new control scheme, let's connect the mouth to a slider like the other kids. You can now use Ctrl itself, and not a duplicate, as this is the last slider we'll need for Box Head. Rename Ctrl to Ctrl_Sync, and you'll need to make one more adjustment. Open the Attribute Editor and limit Ctrl_Sync's motion in Y, so the maximum is 0. Now, select Mouth, open the MouthShapes node under the inputs (below the Channel Box), then select and right-click over WideNarrow. Once in the Expression Editor, select WideNarrow from the list on the right, and in the Expression that appears, rewrite the whole thing to read:

MouthShapes.WideNarrow = Ctrl_Sync.translateX

And then change the expression on the OpenClosed attribute to:

MouthShapes.OpenClosed = -Ctrl_Sync.translateY

You've now got yourself one rigged-up face that works very similarly to the more complicated setups later on. For ease of use (and the reason we moved the expression on Mouth over to a new slider), you can now, if you like, turn off locators' visibility (Show ¢ Locators (Off)), and you won't select the wrong things, just your new sliders. Also, if it makes it easier for you to differentiate them, reshape the circles to be more like icons as I've done in Figure 7.15, or label them.

Figure 7.15: A snapshot of my own little icon creations for each slider: top left is the face, top right is the brows, bottom left is the eyes, bottom right is the lids, and far right is the sync control.

Using "Box Head"

The best thing I can do for starters is take you through some examples of things like the tilt of the head, and the eyelids following the eyeballs, which you've heard about but not yet seen in action. Here I'll acquaint you with the tools, and then we'll use the face to create some expressions and emotions, so you can see in practice how things work.

The tilt of the head, in action

Just do it. Just move the Ctrl_Face slider up and down to alter the tilt of the head, and watch as the eyeballs' relationship to the brows changes dramatically, due to distance relationships and perspective (Figure 7.16). This is how I recommend getting most of the brow up/down effects, by moving the head rather than the brows.]. Granted, the proportion in this setup is as if our character had a 4-inch forehead, but it does make the point, and gives you something very obvious to practice with. Figure 7.16: The expanded and contracted distances perceived during tilts of the head are pretty extreme.


The eyelids following the eyeballs

Take the Ctrl_Lids and slide it downward so that your new character looks unimpressed or sleepy (Figure 7.17). Now move the EyesCtrl around, and watch the lids follow-no matter where the eyes are looking. Even on this simple face the added reality of the lids tracking is pretty neat, but when you get this on a realistic face it's creepy. I find myself playing with this part of the setup for hours, even though I've seen it a hundred times before.

Figure 7.17: The eyelids' tracking is extremely helpful in maintaining expressions.

Adding the lower lids

Go ahead and create yourself a little angry face. Pull Ctrl_Brows down and to the right, tilt the head forward to condense the space between the Brows and Eyes further, and take a look (Figure 7.18). Now move Ctrl_Lids to the left, adding some squint into the mix. Bounce back and forth including, and not including, the squint, to see the big difference it makes. As I've said before, it intensifies this as well as any other expression.

Figure 7.18: An angry face on Box Head, with and without the squint/lower lids


Okay, playtime's over for now, but to keep you fresh on the uses of things, Table 7.1 is a cheat-sheet for Box Head's interface:

Table 7.1: Box Head Cheat Sheet

Ctrl_Face up/down Tilts the entire head forward and back. Condenses and expands the vertical distances between features.
Ctrl_Face left/right Turns the head left and right, only in a limited way because this face is really only meant to be seen from the front.
Ctrl_Eyes up/down Moves the eyes up and down within a range.
Ctrl_Eyes left/right Moves the eyes left and right within a range.
Ctrl_Lids up/down Moves the upper eye lids up and down. Shows alertness.
Ctrl_Lids left/right Moves the lower lids up and down. Increases and decreases emotional intensity.
Ctrl_Brows up/down Moves the brows up and down. Only applies contextually, has no guaranteed effect without other influences.
Ctrl_Brows left/right Moves between the brows looking sad and mad.

Rules of the Game

Our eyes move around a lot. They move around to look at different things we need to know about, or just want to observe. Our eyes also sometimes move not just to things, but away from them as well. Avoiding eye contact or shielding ourselves from things too bright are reasons our eyes would be doing some avoiding. I've said before, and I'll elaborate now, that the eyes themselves tell us next to nothing about emotion. It's all in the context, and it's all in the timing.

When I say context, I mean in plot-related scene, immediate situation, and also in physical surroundings. The eyes looking down when the brows are up and have a sad shape to them gives a different effect than they do when the brows are down with a mad shape-and further variations are possible by changing the height of the lids. Try to erase any preconceived notions of specific eye positions meaning different things, because right now we're going to lay down new types of rules. With lip sync we had visimes, for most of the important shapes. Most of those have pretty solid definitions, but some, like R and T, had referential or relative definitions: wider than this, narrower than that. With the eyes, the level of focus or distraction is almost 100% referential and relative.

"Almost," I say, because there are a few rules.

Eye Rules: Focus and Distraction

Most everything I consider a rule for the eyes has to do with focus and distraction, both for the character and for the audience. There's the focus as tied to the motion, there's timing, and there's involuntary distraction (which can rip an audience out of your scene).

Focus and Motion

The eyes move around, but not randomly. In real life when people are having a discussion and a person is darting their eyes around, their eyes aren't in constant motion. They move, and they stop. After a period of time, they move again, but they stop again. It is highly unnatural behavior for our eyes to not focus on something, anything, if they can, which is what causes the moving and stopping as opposed to a constant, even scanning. The eyes are moving from one focus to another. I tell you this so that in the next sections dealing with specific instances of focus and distraction, you'll realize that eye motion, even if it's ongoing, is not constant. There are pauses and breaks. The eyes cannot scan across a room; they must bounce from focus to focus. This is the nature of the movement. Disregard it and lose your audience. The one apparent hole in this methodology is when someone's eyes are following something that is moving-which, really, is the same rule of focus; it's just that the focus isn't still.

Some of you may be thinking, as I myself did for some time, that this eye motion rule does not apply to stylized characters. Unfortunately, it does. Even the most ridiculously styled characters in CG must have eye behavior reflecting realistic human motion. The likely reason, I've come to realize, is the way that CGI looks. An eye in computer graphics, even a badly modeled and textured one, looks a lot like an eye. Maybe it's the way computers have perfected specular highlights, maybe it's the quality of renderers-who knows. All that matters is that since the eyeballs look like eyeballs, we expect them to behave that way.

Think of a green eyeball of a monster: Mr. Mike Wazowski. Even he, as odd and far from reality as he was, had realistic timing, motion, and acting in that big ol' eye.

Created: March 27, 2003
Revised: November 7, 2003