3D Animation - An Introduction to Computer Graphics for Artists - page 233

Chapter 13
3D Animation

13.1 Introduction

Animation in CG is change over time. This can be any change at all: a box falling,
a person walking, or a camera zooming from a long shot to a close-up. To show each
of these transitions, time is required. In CG, time is represented by sequentially
numbered frames. Whenever the frames are not identical, something has been
animated, even if nothing is moving. It might be that the visibility of an object is
turned on or off, or a texture map changes. Regardless what it is that is modifi ed, it
is animation and animation adds life to a scene. All of the work done to this point
has been done to get your scene ready for animation, because this is where the fi nal
product is made complete.
This topic is primarily concerned with modeling and texturing, so animation will
be covered here only to the extent it affects modeling or texturing choices.

13.2 Previs

In feature fi lms, a scene is an environment, sometimes populated with props and
characters, designed to contribute to the narrative goals of the story it is a part of. In
video games, a scene is similar, though it provides an environment within which
players interact with the game mechanic. In CG, preparing a scene during the
pre-production stage of development is called any one of the following: pre-produc-
tion, production design , concept design , or previs (short for previsualization ) (Falk
et al. 2004 ; Northam et al. 2012 ). The purpose of these, which will be referred to
collectively here as “previs”, is to design the elements of a scene prior to building
them. This is to increase the effi ciency of the production process as well as to create
documents used by team members as reference. For fi lm, animation is of central
importance to previs work because it is here that all major decisions about animation
in the fi lm are made.