Giáo trình đồ họa

Giáo trình đồ họa

(c) SE/FIT/HUT 2002

Lesson 1:

Kӻ thuұt ÿӗ hӑa và HiӋn thӵc ҧo

Computer Graphics And Virtual Reality

„ Kӻ Thuұt ÿӗ hӑa cѫ sӣ

„ Kӻ Thuұt ÿӗ hӑa tiên tiӃn

„ HiӋn thӵc ҧo - VRML

Le Tan Hung

hunglt@it-hut.edu.vn

Tәng quan vӅ kӻ thuұt ÿӗ hoҥ

‰Các khái niӋm tәng quan cӫa kӻ thuұt ÿӗ hoҥ máy tính

‰Các kӻ thuұt ÿӗ hoҥ

‰Phân loҥi các lƭnh vӵc cӫa kӻ thuұt ÿӗ hoҥ

‰HӋ ÿӗ hӑa tѭѫng tác (interactive)

‰Phҫn cӭng ÿӗ hoҥ (Graphics Hardware)

A Brief History of Computer

Graphics

1885 - CRT (Cathode Ray Tube)

1887 - Edison patents motion picture camera

record motion picture photos

on a wax cylinder

A Brief History of Computer Graphics

invents the television.

30 line vertical,

black and red scan

A Brief History of Computer

Graphics

1963

„One of the First General

Purpose Mainframes

A Brief History of Computer Graphics

1966

Odyssey Pinball

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A Brief History of Computer

Graphics

1967

simulator for NASA

A Brief History of Computer Graphics

1968

In "Permutations," (1968) he delineates a marvellous and exciting new world One senses a choreographer The movements are reminiscent of traditional ballet The shapes follow the dictates of formal geometry more than those of abstract painting Movement is three-dimensional and the ambition for a more polished three-dimensional shaded space is apparent

A Brief History of Computer

Graphics

1973

“Westworld” uses 2D graphics

„ First time computer is used for image

manipulation

„ Featured scenes that showed

audiences the world viewed by the

eye circuitry of a synthetic human

(played by a very real Yul Brenner) in

a future Western theme park This

effect was achieved with 2D

computer graphics tools mostly

derived from image processing

techniques

A Brief History of Computer Graphics

1974

1975

„ Mandelbrot plots fractals

A Brief History of Computer

Graphics

1976

Apple.

1977

and Sciences introduces Visual

Effects category for Oscars.

A Brief History of Computer Graphics

1977

„ Star Wars wins oscar for

special effects.

1978

• Superman wins oscar for special effects.

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A Brief History of Computer

Graphics

1979

„ Alien wins oscar for visual

effects.

1980

•The Empire Strikes Back wins oscar for visual effects.

A Brief History of Computer Graphics

1980

live action film with over

20 mins of computer animations.

releases the HDD for PCs

A Brief History of Computer

Graphics

8088 chip)

• Raiders of the

Lost Ark wins

an oscar for

visual effects.

A Brief History of Computer Graphics

1982

for Startrek II is the first all computer animated visual effects shot for film.

A Brief History of Computer

Graphics

1983

„ First Coke Polar Bears

Commercial

A Brief History of Computer Graphics

1985

first live action feature film with realistic computer animation of highly detailed models.

(c) SE/FIT/HUT 2003 19

A Brief History of Computer

Graphics

1989

„ The Abyss is the first

movie to include

convincing 3D character

animation.

A Brief History of Computer Graphics

1990

1993

1994

A Brief History of Computer

Graphics

1995

Id Software

the first fully 3D

computer animation

feature film.

A Brief History of Computer Graphics

1996

wins oscar for visual effects.

A Brief History of Computer

Graphics

1997

„ Titanic wins oscar

for visual effects

for best short film:

Geri’s Game.

A Brief History of Computer Graphics

1998

1999

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A Brief History of Computer

Graphics

2000

„ Sony Playstation II

creating images with a computer

model –

Interactive Computer Graphics:

K ӻ thuұt ÿӗ hoҥ ÿiӇm

(Sample based-Graphics)

„ Các mô hình, hình ҧnh cӫa các ÿӕi tѭӧng ÿѭӧc hiӇn thӏ

thông qua tӯng pixel (tӯng mүu rӡi rҥc)

„ Ĉһc ÿiӇm:

„ Phѭѫng pháp ÿӇ tҥo ra các pixel

(c) SE/FIT/HUT 2003

Bitmap

lines,areas,

SRGP library

Pascal / C program

X Window System Graphics hardware

Image

image formats, compression, transfer

graphics algorithms colour

positions

Graphical

Model

Rendering

Output Device

Rendering Parameters

K ӻ thuұt ÿӗ hoҥ vector

model + rendering

(c) SE/FIT/HUT 2003 31

Muscle Model Wireframe Model Skeletal Model

Skin Hair Render and Touch up

â Walt Disney and TSL

Raster and Vector Graphics

„ Raster

„ Hỡnh ҧnh và mụ hỡnh cӫa cỏc vұt thӇ ÿѭӧc biӇu diӉn bӣi tұp hӧp cỏc ÿiӇm cӫa grid

„ Thay ÿәi thuӝc tớnh cӫa cỏc pixel => thay ÿәi tӯng phҫn và tӯng vựng cӫa hỡnh ҧnh.

„ Copy ÿѭӧc cỏc pixel tӯ mӝt hỡnh ҧnh này sang hỡnh ҧnh khỏc

„ Vector

„ Khụng thayÿәi thuӝc tớnh cӫa tӯng ÿiӇm trӵc tiӃp

„ Xӱ lý vӟi tӯng thành phҫn hỡnh hӑc cѫ sӣ cӫa nú và thӵc hiӋn quỏ trỡnh tụ trỏt và hiӇn thӏ lҥi

„ Quan sỏt hỡnhҧnh và mụ hỡnh cӫa hỡnh ҧnh và sӵ vұt ӣ nhiӅu gúc

ÿӝ khỏc nhau bҵng cỏch thay ÿәi ÿiӇm nhỡn và gúc nhỡn

Phõn lo ҥi cỏc lƭnh vӵc cӫa

Computer Graphics

Kỹ thuật phân tích vμ tạo ảnh

Đồ hoạ hoạt hình vμ

nghệ thuật

Kỹ thuật nhận dạng

Xử lý ảnh

Đồ hoạ minh hoạ CAD/CAM System

Kỹ thuật đồ

hoạ

Kiến tạo đồ hoạ

Xử lý đồ hoạ

Phõn lo ҥi theo hӋ toҥ ÿӝ

Kỹ thuật đồ hoạ

Kỹ thuật đồ hoạ 2 chiều

Kỹ thuật đồ hoạ ba chiều

Phõn lo ҥi theo chӭc năng

attempt to provide meaning to computer) images.

Cỏc ӭng dөng tiờu biӇu cӫa kӻ thuұt ÿӗ hӑa

„ Xõy dӵng giao diӋn ngѭӡi dựng (User Interface)

„ Tҥo cỏc biӇu ÿӗ trong thѭѫng mҥi, khoa hӑc, kӻ thuұt

„ Tӵ ÿӝng hoỏ văn phũng và chӃ bҧn ÿiӋn tӱ

„ ThiӃt kӃ vӟi sӵ trӧ giỳp cӫa mỏy tớnh (CAD_CAM)

„ Lƭnh vӵc giҧi trớ, nghӋ thuұt và mụ phӓng

„ ĈiӅu khiӇn cỏc quỏ trỡnh sҧn xuҩt (Process Control)

„ Lƭnh vӵc bҧn ÿӗ (Cartography)

(c) SE/FIT/HUT 2003 39

CAD-CAM application

H Ӌ ÿӗ hӑa tѭѫng tác

ƒ Mô hình hӋ ÿӗ hoҥ tѭѫng tác

ƒ Các thành phҫn cӫa hӋ ÿӗ hoҥ tѭѫng tác

ƒ Bӝ xӱ lý tѭѫng tác vӟi ngѭӡi sӱ dөng

ƒ Các chuҭn cӫa hӋ ÿӗ hoҥ

concerned with:

- hardware

- how to display

(rasterization)

concerned with:

- modeling

- modeling transf

- color models

- material property

- lighting property

G U I

MODELING RENDERING DISPLAYING

what is

a table, a car, x

x x

( to describe)

to the computer

Geometric Engine

(to capture)

the description create 2D image from 2D / 3D models

Rendering Engine

generate image on screen

(to show)

the image

Raster & Display Engine

concerned with :

- viewing & projection

- drawing & clipping

primitives

- local illumination &

shading

- texture mapping

Th ành phҫn trong chӭc năng cӫa

kӻ thuұt ÿӗ hoҥ Cá thành phҫn cӫa hӋ ÿ hoҥ tѭѫng tѭѫng tá

Application Data Structure

Application Program

Graphics System

Computer Graphics Devices

(c) SE/FIT/HUT 2003 43

Model of RGP

Application

model

Application

Display Hardware output pipeline

input pipeline

output primitives output attributes Canvascontrol copyPixel

Input device measures Input device control

(c) SE/FIT/HUT 2003

3D Graphics Over World Wide Web

3D Graphics Over World Wide Web

SRGP library

Pascal / C program

X Window System Graphics hardware

Image

image formats, compression, transfer

graphics algorithms colour

Drawing packages transformation

of objects

3D Graphics projections lighting,shading

lines,areas,

positions

Video WWW

Animation

WWW VRML

Thành phҫn thѭ viӋn ÿӗ hoҥ

„ Các thӵc thӇ cѫ sӣ

ƒ ĈiӇm (pixel)

ƒ Ĉѭӡng thҷng (line)

ƒ Ĉѭӡng tròn (circle)

„Ĉa giác (polygon) v v.

„ Các thuӝc tính

ƒ Màu sҳc (color)

ƒ KiӇu ÿѭӡng vӁ (line style)

ƒ KiӇu văn bҧn (text style)

„ Mүu tô (pattern).

B ӝ xӱ lý tѭѫng tác vӟi ngѭӡi sӱ

d өng

„ HӋ thӕng ÿӗ hoҥ thông thѭӡng phҧi chӭa mӝt tұp hӧp các thӫ tөc (chѭѫng trình con) ÿӇ xӱ lý vӟi các thiӃt bӏ vào ra (I/O System)

„ hӋ thӕng ÿӗ hoҥ sinh ra các thiӃt bӏ ngoҥi vi lôgic ÿӇ tѭѫng tác giӳa ngѭӡi sӱ dөng và thiӃt bӏ ngoҥi vi này.

„ Mӝt chu trình ÿiӇn hình cӫa các chѭѫng trình ӭng dөng quҧn lý các thiӃt bӏ ngoҥi vi ÿѭӧc gӑi là vòng lһp sӵ kiӋn tӯ thiӃt bӏ (event-driven loop )

HӋ thӕng ÿӗ hoҥ

(Graphics System)

„ Interface between application software and graphics hardware system

„ Consists of input subroutines and output subroutines accepting input data or

commands from a user and converting internal representations into external

pictures on screen, respectively

„ Ph̯n m͉m ÿ͛ ho̩ h͏ th͙ng:

„ Là tұp hӧp các lӋnh ÿӗ hoҥ cӫa hӋ thӕng (graphics output commands),

„ Thӵc hiӋn công viӋc hiӇn thӏ cái gì (what object) và chúng sӁ ÿѭӧc hiӇn thӏ nhѭ

thӃ nào (how)

„ Phҫn mӅm ÿӗ hoҥ hӋ thӕng là phҫn mӅm xây dӵng trên cѫ sӣ mӝt thӇ loҥi phҫn

cӭng nhҩt ÿӏnh và phө thuӝc vào phҫn cӭng

„ Ph̯n cͱng ÿ͛ ho̩:

„ Là tұp hӧp các thiӃt bӏ ÿiӋn tӱ (CPU, bӝ nhӟ màn hình) giúp cho viӋc thӵc hiӋn

các phҫn mӅm ÿӗ hoҥ

Application program Graphics system

Graphics hardware

Input and output devices

Core, GKS, GKS-3D CGI (device interface) CGM (metafile) PHIGS (3D and realtime) X-window

PHIGS+ (PEX) IGES

OpenGL DirectX

Metafiles

Operating system

Giao d i Ӊn hӉ thӓng ÿӕhӏa

Interface of Graphics System

(c) SE/FIT/HUT 2003 49

Các chuҭn giao di Ӌn cӫa hӋ ÿӗ hoҥ

„ GKS Functional Description, ANSI X3.124 - 1985.

„ GKS - 3D Functional Description, ISO Doc #8805:1988.

„PHIGS Functional Description, ANSI X3.144 - 1985.

„PHIGS+ Functional Description, 1988, 1992.

„ IGES

Non-official industry standards

Các chuҭn cӫa hӋ ÿӗ hoҥ

OpenGL

„ Software interface to graphics

hardware

„ Client-server model

„ Object specification + image

generation

„ Simple primitives: points, lines,

polygons (pixels, images, bitmaps)

using client-server model

„Client (Application) issues commands

„Server (OpenGL) interprets and processes commands

„Frame buffer configuration done by the window system

„ Direct control of graphics hardware

„ Direct control of input/output devices, and sound

Application program

Windows system

Direct sound Direct draw Direct 3D

Direct input

Windows API

……

DirectX

Các thi Ӄt bӏ vào ra dӳ liӋu

„ Máy in

in có thӇ in ÿѭӧc

ƒ Addressability: khҧ năng ÿӏa chӍ hoá các ÿiӇm in có thӇ

có trên mӝt ÿѫn vӏ ÿӝ dài (dot per inch)

ƒ Sӕ lѭӧng màu có thӇ vӁ trên mӝt ÿiӇm

Phҫn cӭng ÿӗ hoҥ (Graphics Hardware)

Phҫn cӭng ÿӗ hoҥ (Graphics Hardware)

„ Các thành phҫn phҫn cӭng cӫa hӋ ÿӗ hoҥ tѭѫng tác

(c) SE/FIT/HUT 2003 55

Màn hình CRT

Màn hình CRT

SONY Trinitron CRT

NEC Hybrid Mask Hitachi EDP Standard Dot-trio

Các thiӃt bӏ hiӇn thӏ dҥng vector

„MOVE 10,15

„LINE 400,300

„LINE 600,800

„Refesh Buffer

DrawLine(A, B):

Turn beam off,

move to A.

Turn beam on,

B

Graphics Devices

Display processor CRT

Alphanumeric keyboard

Stylus

Data tablet

Interface to host computer

… MOVE 10 LINE 100 25 CHAR LU LINE

… JMP

Refresh buffer memory

(Display commands) (interaction data)

Display processor CRT

Interface to host computer

(Display commands) (interaction data)

Keyboard Data input

00000000000000000000000001000000

00000000000000000000000111110000

00000000111100000000000111110000

00001111111111110000000001000000

00011111111111111000000000000000

00011111111111111000000000000000

Bitmap refresh buffer

(the 1’s are accentuated

for contrast)

Typical raster graphics display

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LCD-Liquid Crystal Display

„ Works by letting varying

amounts of a fixed-intensity

white backlight through an

active filter

„ Organnic crystals that lign

themselves together

„ When external force is applied

they realign themselves

„ This is used to change

polarisation and filter light

CRT Displays

Advantages

„ Fast repsonse (high resolution possible)

„ Full color (large modulation depth of E-beam)

„ Saturated and natural colors

„ Inexpensive, matured technology

„ Wide angle, high contrast and brightness

Disadvantages

„ Large and heavy (typ 70x70

cm, 15 kg)

140W)

and magnetic fields

„ Flickering at 50-80 Hz (no memory effect)

„ Geometrical errors at edges

LCD Displays

Advantages

„ Small footprint (approx 1/6 of CRT)

„ Light weight (typ 1/5 of CRT)

„ Low power consumption (typ 1/4 of

CRT)

„ Completely flat screen - no

geometrical errors

„ Crisp pictures - digital and uniform

colors

„ No electromagnetic emission

„ Fully digital signal processing

possible

„ Large screens (>20 inch) on desktops

Disadvantages

„ High price (presently 3x CRT)

„ Poor viewing angle (typ +/- 50 degrees)

„ Low contrast and luminance (typ

1:100)

„ Low luminance (typ 200 cd/m2)

Future Research Areas Hѭӝng nghiên cӫu

„parallel processing

„physically-based modeling

„level of detail

synthesis

„kinematics / dynamics

„motion capture/

modification

„photo-realism

„real-time

„image-based rendering

„non-photorealistic rendering