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第三章 基本觀念

電腦繪圖與動畫 (Computer Graphics & Animation)

Object Data Image

物體資料數據

Scan Conversion

影像

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Object( 物體 )

Data( 數據 )

Graphics Command( 指令 )

Graphics Application Program

Display Processor

Scan Conversion

點、線、圓

曲線、面

特殊效果Frame Buffer （硬體及軟體）

Display Controller （硬體）

Monitor （螢幕）

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Geometric Data Object Image

幾何資料物件 影像

Object Image

Computer Graphics

Image Processing Pattern Recognition

Computer Graphics

Creation 建構

Manipulation 操作

Display 顯示

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CAD

CAD/CAM 電腦輔助設計與製造

對象： 幾何

要求： 事實

目的： 設計、分析、應用

Computer Graphics 電腦繪圖對象： 畫素

要求： 效果

目的： 表現、模擬、互動

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Computer Graphics 電腦繪圖

何謂電腦繪圖？ What is Computer Graphics ？

Communication between human beings and computers

用電腦化的方法來創造、操作及顯示影像

Defined as creation,manipulation and display of graphic images by computerized method

Include Creation

Manipulation

Display

StoringViewing ModificationAnalysisRetrieving

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Study scope

數據

輸入裝置

？ HOWComputer Graphics

輸出裝置

影像

DataData

Input DeviceInput Device

Output Display DeviceOutput Display Device

ImageImage

電腦繪圖方法

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Design Cycle

Specification and RequirementSpecification and Requirement

Creation of DesignCreation of Design

Analysis and EvaluationAnalysis and Evaluation

Manufacturing and salesManufacturing and sales

…

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CAD

Computer-Aided Drafting

Computer-Aided Drawing

How to draw image

Computer-Aided Design

How to designHow to represent a modelHow to use data for application

Computer-Aided Design

How to displaydata Image

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Pixels

Graphic entity

Scan Conversion

Scan Conversion

FrameBufferFrameBuffer

DisplayImage

DisplayImage

Display processor Memory Display Controller

Each Pixel In 2-D array memory

…………………………

pixels

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CGA (Computer Graphics Adapter)

EGA (Enhanced Graphics Adapter)

VGA (Video Graphics Adapter)

640*480

SVGA (Super VGA)

800*600

XGA 1024*768

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VectorBitmap Raster

向量空間影像空間

ObjectGeometricDefinition

ObjectGeometricDefinition

ImagePixel

Definition

ImagePixel

Definition

Computer Graphics

Object Space

Vector Space

（ x2,y2 ）

（ x1,y1 ）

LineDefinition

Image Space

Bitmap Space

Pixel position definition

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Raster DisplayRaster-Scan

Picture on screen as a set of Pixel points 畫素

Raster Display ScreenExample ：resolution640*480 （ VGA ）Scan Line pattern

12345

Scan from ： Left to Right Top to Bottom

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Illuminating Pixels

Scan Conversion

Scan Conversion

FrameBuffer

FrameBuffer

DisplayImage

DisplayImage

Display processor Memory Display controller

。 Each pixel in 2-D array in memory

Frame bufferbitmap

。 512*512 display screen requires 262,144 pixel memory address

。 1M 2M,……

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0110000

1001110

0001100Frame Buffer Display Image on Screen

Each pixel is an （ x,y ） coordinate on Screen

x

y .To display （ x,y ） pixel onscreen

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Black and White 2 intensity level ON/OFF

Single-bit-plane frame buffer

Black and White with shades color

Additional bit-planes

3 bit-plane

7123

8 intensity level

0~7

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Black and White TV8 bit planes

25628 Intensity level 明暗度

High quality color

24 bit planesEach with Primary colors （ RGB ）

Red ， Green ， Blue216,777,16224 colors

VGA 640*400*8=256K800*600*8=480K 256 colors

1024*768*8 通常 1M1024*768 true 24 bit color 通常 2M

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3-bit ， N bit 彩色

色823

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24-bit 彩色

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電腦繪圖畫線由點的轉換

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Route through aEnu tree

Typical screen layout