Inverse Kinematics - Kinematics is a chain of parts (for example, upper arm + forearm + hand + finger) that move together because they're connected. Inverse means you move it from the end of the chain instead of the beginning. For example, it allows you to grab the tip of a figure's finger and move the whole arm.

Motion Capture - The process of hooking up computer sensors to an actor's body to track the movement of the actor. The motion capture files can then be used to animate computer generated figures.

Motion Library - Files describing movement that can be applied to different computer-animated objects.

Motion Path - A spline path in a computer scene that allows the animator to attach an object to move along.

Pixel - A PICture Element. Television screens are made up of pixels. If you look very close at your television screen you can see the individual squares that make up the pattern of an image.

Polygon - An object made up of straight sides (vertices). More detail and curvature can be created by making the vertices smaller or by using rendering tricks to smooth them.

A photorealistsic alley scene, courtesy of Avalanche Productions.

Raytracer - A highly accurate mathematical process of shading an image where every pixel has a light ray shot through it from the light source which contacts any object in that pixel and then records it back to the camera.

Render - The computer process of generating an image.

RGB - Light is made of three primary colors, Red, Green and Blue (R-G-B). Computer colors used for video are usually expressed in numbers for each primary color. In 24 bit color each R-G-B value has a number between 0 (no light value) and 255 (full light value). Black is expressed as 0 ,0 ,0. Pure white is expressed as 255, 255, 255. A pure red would be expressed as 255,0,0. A value of orange could be 128, 128, 0.

Rotoscope - An image or sequence of images used as templates in Animation:Master.

Scan - In 3D, the process of using a device to accurately measure the surfaces of an object for use in a computer environment.

Spline - An infinitely elastic building element of spline modelers. In the hands of the inexperienced it can end up looking like a plate of spaghetti.

Stride Length - The ability of measuring the length of a stride on the walk cycle of a computer character so that when the character is placed on a motion path, the legs move proportionally and don't skate across the ground. It can also be applied to round objects such as car wheels.

Tim Elston is a 3D modeler/animator based in Grass Valley, California. He has been a professional animator for 20 years, and spent 10 years in the animation industry in Los Angeles before learning the digital side of animation. His credits include work for Computoons, 3DO and The Oregon Museum of Science and Industry. He is now working on a virtual museum project for The Museum of Ancient and Modern Art, and has several other projects in development.