Overview of 3D animation technique

The use of computer generated imagery (CGI) is growing rapidly, from special effects in live action films to full-length animation.

3D animation was first used in the 1980s and has been popularised recently by films like Toy Story and Shrek. Now used extensively in 2D animation to provide backgrounds and props, CGI is also used to create crowd scenes, in history programmes like Walking with Dinosaurs and in adverts like Xbox Mosquito, Levis Odyssey and Mercedes Clouds.

An audience needs to believe that the characters and backgrounds in a 3D animation are operating in a 'real' way. Light, shadow, texture and shape must behave realistically, even if the environment is fantastical. 3D animators go through a complex process to bring their animation to life and have a pallet of tools and effects that they use to make a scene look realistic:

Story Development

The first part of the animation process is to develop an idea into a story board which maps out how the action of the film will develop. The full script of the animation is then written and, if dialogue if featured, recorded by actors.

Wireframe Models

Story boards are then transferred to computer, this process is much like the first stages of a paper-mache sculpture where chicken wire is bent into shape to make the outline.

3D animators start by drawing basic shapes. In its first stage, a finger might be created by stacking together lots of cubes with a triangle on top.

This image is then divided, like a grid, into much smaller areas which can be manipulated at the points where gridlines cross.   By pushing and pulling the tiny hinges on the grid-like shape, the illusion of curves can be created and a much more natural image is achieved.   This is also how animators achieve 3D movement.

Texture Map

To increase the realism of the wireframe model, colour, shade and texture to must be added. Animation software packages offer pre-programmed tools to control a surface's appearance, or animators can create their own textures.

At this stage computer generated curved lines may still seem stilted or jagged, so animators use optical illusions to fool the eye into seeing them as smooth. This effect is called anti-aliasing and is achieved by graduating the colour of the pixels that appear next to the line. Other effects like the blurring of objects in a scene's background, are used to recreate the human eye's natural depth of field.

The animator must also choose a light source for the scene and then plot how the light will bounce off the people and objects in it, taking into consideration how different surfaces reflect light in different ways. Just as light gives a scene depth, similarly shadows give weight to an object, making the scene look more natural.

Rendering

The animator has now created a large amount of data files relating to how the animation should look. The last stage of animation is rendering, a process that integrates all of the computer generated information into one file. Rendering is hugely computer intensive and can take many days to complete.

Post production

Finally, sound effects and music are added on and the animation is converted into a distributable format.

For further info visit

http://entertainment.howstuffworks.com/3dgraphics2.htm

http://www.pixar.com/howwedoit/index.html