Introduction

Tom Kelliher, CS 320

Jan. 24, 2000

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Assignment

From Last Time

Terminology.

Outline

1. Terminology.

2. Graphics system architecture, CRT structure.

3. Graphics: a synthetic world.

Coming Up

OpenGL programming.

Introduction

Terminology

1. Interlaced, non-interlaced.

2. Bitmap, pixmap.

3. Transparent, opaque.

4. Aliasing.

5. Persistence.

Graphics System Architecture

Overall architecture:

Hardware components:

1. Processor.

2. Memory.

3. Frame buffer.

4. Input, output devices.

CRTs

Monochrome:

1. Electron Gun.

2. Focus.

3. X-, y-deflection coils.

4. phosphor.

Color:

1. Electron gun s: R, G, B.

2. Shadow mask.

3. Triads on the phosphor.

4. Color mixing: intensity.

5. Additive effects of RGB.

6. Monitors are analog, but frame buffers are digital. ``True color.''

A Synthetic World

Here, we take a high-level view of computer graphics.

Introduction

Name two necessary components for image formation:

1. Object.

2. Viewer.

Are object and viewer sufficient? What about light? How do we model light?

Simplifications:

1. Point light sources. How good a model? Properties of light sources:
   1. Position.

   2. Intensity.

   3. Color.

   4. Directionality.

2. Monochromatic light. Not a restriction, due to additive properties of light.

Radiating Light: Ray Tracing

Rays radiate from light sources in all directions. They can:

1. Travel directly to viewer.

2. Travel to infinity, not being viewed.

3. Reflect from object and travel to viewer.

4. Pass through object and travel to viewer.

5. Interact with several objects before traveling to viewer.

6. Etc.

Material properties of object:

1. Transparent/Opaque.

2. Reflect/Diffuse.

3. Refract.

Ray tracing is a scene illuminating technique based on these ideas.

A problem: the computational complexity.