Invitation to Computer Science 5 th Edition Chapter 16 Computer Graphics and Entertainment: Movies, Games, and Virtual Communities

Invitation to Computer Science 5th Edition

Chapter 16

Computer Graphics and Entertainment: Movies, Games, and

Virtual Communities

Invitation to Computer Science, 5th Edition 2

Objectives

In this chapter, you will learn about:

• Computer-generated imagery (CGI)

• Video gaming

• Multiplayer games and virtual communities


Introduction

• Computer-based entertainment – A $15–20 billion industry

• By the start of the twenty-first century:– Entertainment had become an application that stands

alongside traditionally “important” uses of computers


Computer-Generated Imagery (CGI)

• Advantages– Can produce extremely high-quality, lifelike images,

called photorealistic animation– Can generate images that are prohibitively expensive

to produce manually– Without it, directors would either have to:

• Hire thousands of extras

• Animate the scenes by hand, or

• Produce thousands of miniature models


How It’s Done: The Graphics Pipeline

• Graphics pipeline– Sequence of operations that must be completed

successfully to produce a realistic three-dimensional image


Figure 16.2 A Simplified Three-Stage Graphics Pipeline


Object Modeling

• First step in generating a three-dimensional image

• Creation of a mathematical or computational model of a three-dimensional object that: – Can be stored in memory and manipulated

algorithmically


Figure 16.3 Wireframe Model of a Dolphin (based on image in Wikipedia entry on polygon meshes)


Figure 16.4(a) Tesselation Producing Three Triangles and Five Vertices


Figure 16.4(b) Vertex List Representation of the Model in Figure 16.4(a)


Object Motion

• Rigid motion – Motion that does not bend or deform an object– Types: translation, rotation, and reflection

• Transformation matrix– Mathematical structure used to implement motions

• Advantage of CGI– Computer can perform many of the required

operations without the assistance of a human designer


Figure 16.5 The Three Types of Rigid Motion


Figure 16.6 Using Matrix Multiplication to Implement Object Translation


Object Motion (continued)

• Keyframing– Human animator only needs to produce:

• The first frame, containing the starting location of the object

• The last frame, containing the final location of the object

• The elapsed time

• Control point– Point or axis used to control the motion of an object


Figure 16.7 Example of a Translation Performed on the Object Shown in Figure 16.4(a)


Figure 16.8 Figure-8 Object

Rendering and Display

• Rendering – Taking an object stored as a mathematical model

and converting it into a fully formed, visually pleasing three-dimensional image

– Often consumes the vast majority of computer time required to produce an image



Rendering and Display (continued)

• Issues addressed during the rendering process– Lighting– Color shading– Shadows– Texture mapping– Blur

• Algorithms for carrying out rendering operations – Ray tracing, rasterization, and radiosity


Figure 16.10 Three Light Sources Illuminating Triangle T


Figure 16.11 Converting an Image to a Two-Dimensional Representation


The Future of CGI

• Parallel and multicore computers – Are becoming more common– Allow computers to overcome Moore’s law and

continue to gain in speed

• Computer scientists– Are discovering newer and better algorithms for such

common CGI operations as modeling, animation, and rendering


Video Gaming

• A movie is a static environment that is created once and shown as often as desired

• A video game is a highly interactive environment

• Real-time graphics– Branch of computer graphics that studies methods

for creating images at a rate matching that of the real world

• Graphics Processing Unit – Common technique for increasing imaging speed


Figure 16.12 Typical Architecture of a GPUand Video Memory


Video Gaming (continued)

• To achieve speedup in real-time graphics: – Avoid the use of algorithms that simply take too

much time

• Culling– Used to speed up rendering and display

• Cut-ins– Fully modeled and fully rendered objects stored in a

video library in video memory


Multiplayer Games and Virtual Communities

• Massively multiplayer on-line games (MMOG) – Allow a large number of players to interact, form

groups, and compete against one another within a simulated virtual world

• Game servers– Special computers used to manage simulated virtual

world

• In an MMOG: – The virtual world in which the game is played is

persistent


Multiplayer Games and Virtual Communities (continued)

• Client software– Users log on to the game server

• MMOG must address and solve the following technical problems– Registration management– Client/server protocols– Security– Database design


Figure 16.13 Architecture of an MMOG


Multiplayer Games and Virtual Communities (continued)

• Noncompetitive MMOG– Simulated virtual world where the goal is not to

destroy your opponent or get the highest score– Purpose of entering this metaverse is to:

• Explore the virtual world

• Interact with other people in the world

• Form communities of residents with similar interests

• Create new economic entities that have (virtual) value


Summary

• Computer-based entertainment – A $15–20 billion industry

• Object modeling– First step in generating a three-dimensional image

• Rigid motion – Motion that does not bend or deform an object

• Rendering – Often consumes the vast majority of computer time

required to produce an image


Summary (continued)

• Graphics Processing Unit – Common technique for increasing imaging speed

• Noncompetitive MMOG– Simulated virtual world where the goal is not to

destroy your opponent or get the highest score

Documents

Invitation to Computer Science 5 th Edition Chapter 16 Computer Graphics and Entertainment: Movies, Games, and Virtual Communities