CPSC 100: Principles of Computer Science
Spring 1997
Week 9 Reading Guide

This is the ninth of the weekly reading guides for Computer Science 100.


Week 9 (May 26 to May 30)

The reading for the last week of the term is Chapter 11, on computer graphics. We will concentrate mostly on the material in Section 1, and the lab on Friday is based on the material on geometric modeling and geometric transformations in that section. However, you should also know some of the basic ideas from Section 2, as listed below.

Sophisticated computer graphics images are built in two stages: modeling and rendering. In the modeling stage, a data structure is created that contains a description of all the objects in a scene. Because these objects are built up out of simple geometric shapes, such as lines and triangles, this phase is also called geometric modeling. The result of this phase is a wireframe model.

Rendering, the second phase of computer graphics, refers to producing the actual visual representation of the scene. This involves deciding how to color each pixel depending on such factors as: what object is visible at that point, properties of that object such as color and texture, lighting conditions, shadows cast by other objects, etc.

Animation can be produced by rendering a sequence of images of the same scene, with objects moved, resized, and/or rotated a bit from one frame to another. These basic operations of moving (or translation), resizing (or scaling), and rotation are called geometric transformations. These transformations are used not just in animating a scene; they are also used to position objects in the scene in the first place.

Concept List for Chapter 11: