Sometimes a character looks correct in one frame and then very strange a couple of frames later. The head gets bigger, the eyes float up, the arms become different lengths, or the jacket rides up the body. All of these minor inconsistencies can cause a noticeable flicker on playback, even if the animation is correct. So consistency is not just a matter of art, it’s a matter of making the animation look good.
It’s much easier to maintain consistency if your construction is simple. Don’t start by adding hair or clothes wrinkles or nose highlights or eyeglasses. Start with simple shapes. Think of the head as a simple volume, the torso as another clear form, and the limbs as connected shapes with predictable lengths. This construction will stay the same even when the character moves. If they turn or bend, the character will look different, but the proportions should remain the same.
Decide what defines the character. Maybe the eye spacing or the size of the head or the shoulder width or the hairstyle is what makes them who they are. Sketch out a character sheet from the front, side and a few angles showing different facial expressions. You don’t need fancy lines, just show the proportions and sizes of the elements of the character so you have a baseline.
Here’s an exercise you can try. Make a simple animation of a character turning their head to the right. Create the keyframes (first, last and middle). Check that the height of the eyes, the size of the head, the location of the ears, and the distance from the top of the head to the bottom of the chin are all roughly the same. Once these keyframes look the same, draw the rest of the frames between them. It’s easier to animate from a base set of keyframes than to draw every frame from scratch.
Use onion skinning to help you spot inconsistencies, but remember that it’s there to help you find errors, not as a rule. As the character moves through space, the pose and position will change. The goal is not to have every single frame overlap. Look at the relationships that don’t change. If the head is shrinking when the character turns their head, or the arm gets longer when they reach, the problem isn’t the animation, it’s the construction.
Play back your animation and look for inconsistencies. Sometimes a mistake in construction doesn’t stand out until you see the animation playing. If the head pulses or wobbles as it turns, stop the animation and compare the frames around it. Redraw the offending frame. It’s much easier to fix one drawing than to redraw a whole sequence. Organize your animation layers so you can quickly undo and try again. Do a rough version before cleaning up so mistakes are cheap.
Don’t get so caught up in being consistent that your animation becomes stiff. Characters can and should stretch, squash, rotate, shift perspective, etc. as they move. The key is that it all looks purposeful and that the character snaps back to normal afterwards. If you’re looking at a drawing and wondering why it looks different, ask yourself, does it look like this because it needs to, or does it look like this because I made a mistake?
