Overview of Computer Graphics

Subjects :

What is C.G

History of C.G

Applications of C.G

C.G vs I.P

Course objectives

What is CG (1/2)

Humans Communicate well with images

1/3 of our brain is devoted to visual processing

A picture is worth a thousand words

• WYSIWYG paradigm

In the past, graphics was only used to convert

numerical data sets to graphs.

business graphs (bar chart, pie chart)

What is CG (2/2)

Nowadays, graphics is used to depict the complex data sets and virtual / natural phenomena.

Virtual Reality(VR), Scientific Visualization(SV)

Definition : Picture style I/O technology involving the Creation manipulation storing and display of pictures with the aid of computer

Numericaldata

Picture (Image)data

input output

HISTORY OF C.G (1/2)

General Trends 1950’s : First military application of graphics Mid 1950 : SAGE (Semi-Automatic Ground Environment) Air Defense System

• first “command and control” CRT with lightpen 1963 : Ivan Sutherland’s sketchpad thesis

• called father of C.G• propose interactive graphics system

1966 : Wall street Journal was writing about C.G and CAD

HISTORY OF C.G (2/2)

Mid 1970’s :

• Emergence of raster graphics display based on T.V technology

• development of raster graphics hereafter

1981 : Apollo introduces first graphics workstation

1984 : Evolution of GUI by Apple Macintoshi

Mid 1980’s : Commercial usage of V.R techniques

Early 1990’s : Scientific Visualization and Volume graphics

Applications of C.G (1/2)

CAD (Computer-Aided Design) for Engineering and Architectural design design of buildings, automobiles, spacecraft, and VLSI

Presentation Graphics for illustration of outputs. bar chart, line graph, pie chart etc.

Computer Art for fine art and commercial art applications.

Applications of C.G (2/2)

Entertainment for special effects of CF, movies Jurassic Park, Terminator II

Education and Training Graphics supported flight simulator CD Rom title

Visualization called Scientific Visualization converting millions of data value into pictures

VR Game S/W, etc

by using CGI(Computer Generated

Imagery)

Computer Graphics vs Image Processing (1/2)

Computer Graphics(C.G) a computer is used to create

a picture.

model based approach

concerns pictorial synthesis of real or imagery objects from computer based model

deals with vector data • ex) Jurrassic park, Game

Computer Graphics vs Image Processing (2/2)

Image Processing (I.P) a computer is used to modify or interpret existing pictures. processing of sensor based data concerns scene analysis.

• improving picture quality

• machine perception of visual info

deals with pixel data

ex) Recognition of car license plate

Interpretation of satellite image

Course objectives : (1/2) generation of photo-realistic Images

Two different views in studying CG A graphics system user’s view (Computer Graphic)

• interested in what images are produced by using graphics S/W

• industrial design, visual art

A system programmer’s view (Computer Graphics)• how to write a physics-based application program (package) for

users.

• interested in the development of fast and accurate graphics software

Course objectives : (2/2)

Related fundamental subjects of C.G are• Computer Science

• mathematics

• physics

• mechanical engineering etc.

C.G S/W consist of

ModelingS/W

RenderingS/W

AnimationS/W

Image Composition S/W for Image Synthesis

+

모 델 링 (Modelling)

대상물체의 형상화를 위해 사용되는 기술 인공물체 : 기하학적 Primitive (선 , 면 , 구 , 육면

체 )등을 이용하여 형상화

• 입력물 : 형상화 물체의 3차원 좌표값• 출력물 : 선구조형상 (Wire framed objects)• 기 법 : Interpolation / Approximation, CGS, Sweeping, Deformation 등

자연물체 : Procedualism 에 의한 형상화• 입력물 : 자연물의 구조를 정의하는 규칙• 출력물 : 선구조 형상• 기 법 : 프랙탈 기법 , Grammar-based modelling, particle

system, physically based modelling 등

애니메이션 (Animation)

Animation is giving variations on the model over time Different keys given by the animator are interpolated to give

in betweens.

2D Animation (Cell Animation)

3D Animation• 기 법 : Key-frame Animation

Kinematics / Inverse Kinematics

Dynamics

Metamorphosis

렌 더 링 (Rendering)

Process of photo-like image generation Rendering adds light to the model The renderer tracks the light in the scene to determine how

the scene looks to the viewer. 기 법 : Hidden elements Removal

Shading

Texture mapping

Ray-tracing

Radiosity

영 상 합 성 (Image Synthesis)

실사와 C.G 기술의 자연스러운 조화기술

예 ) Jumanjii, photoshop S/W

기술내용 :

• Image processing 기술

• Film 의 Digital 변형기술

• Digital 합성기술

• Color Composition / Correction 기술