The Basics of 3D Animation

Animation in 3D applications usually happens in two primary ways. In major productions, both may be used. 

1. Keyframe animation - Keyframe animation, or keyframing, is the most well-known and oldest style of animation. In fact, there are examples of frame-by-frame animation dating all the way back to 1600 B.C. Egypt! Modern keyframing techniques date back to the early cartoons created by animation pioneers like Winsor McCay and Walt Disney. What may surprise you is that keyframing techniques have not changed much since the early 1900's - most of the basic principles still apply today. What has changed is that 3D software packages have made keyframing much easier to accomplish, meaning a broader scope of artists can learn how to animate.

Keyframing is essentially changing the shape, position, spacing, or timing of an object in successive frames, with major changes to the object being the key frames. In traditional 2D animation, each frame is usually drawn by hand. When frames are shown in succession, as in a movie, the slight differences in each frame of animation create the illusion of motion. 3D software packages make keyframe animation easier by interpolating, or "tweening," the in-between frames. When animating a falling ball, for example, one key frame might be of the ball in mid-air, the next key frame may be the ball touching the ground, and the key frame after that would be the ball squishing down as the impact deforms its shape. All of the in-between frames are then calculated by the software automatically, including the squish at the bottom, making actual process of animation a matter of creating a few great key frames.

2. Motion capture - Motion capture, or mocap, was first used sparingly due to the limitations of the technology, but is seeing increased acceptance in everything from video game animation to CG effects in movies as the technique matures. Whereas keyframing is a precise, but slow animation method, motion capture offers an immediacy not found in traditional animation techniques. Mocap subjects, usually actors, are placed in a special suit containing sensors that record the motion of their limbs as they move. The data is then linked to the rig of a 3D character and translated into animation by the 3D software.

There are a couple downsides to motion capture which make it difficult for beginning 3D animators to learn. Firstly is the cost of mocap technology, which can run several thousands or even tens of thousands of dollars. This means that most new 3D artists must learn to incorporate this animation style by importing mocap data into a project from a commercially available mocap library.

The other downside to mocap is that the end-result is often far from perfect; mocap animation usually requires clean-up from keyframe artists to make it look more realistic, especially if the character being animated does not have an anatomy or proportions similar to those of a human.