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電機四 陳人豪

Outline

History of computer graphics Computer graphics pipeline Introduction to animation

History

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

SAGE system, WWII Air defense system

Dr. Ivan Sutherland (MIT), 1963 Invent Sketchpad Interactive design on vector

graphics The origin of computer graphics

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

First raster display, 1966 What is raster scan? Display or capture image

line by line

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

Apple II, 1977 帶起 PC 革命 彩色圖形介面

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

Tron, 1982, Disney 中文翻譯 “電子世界爭霸戰” 第一部運用動畫手法拍攝的電影 創造了電影史上第一個數位角色

“ Tron” 在迪士尼頻道有播出過

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

Toy Story, 1995, Pixar 第一部 3D 動畫長片 Woody 跟 Buzz Lightyear 之間

的愛恨情仇

萌芽期

(60’s~mid 70’s)

發展期

(late 70’s~80’s)

成熟期

(90’s~00’s)

History

目前在許多領域都有發揮 Interactive environment Scientific & medical visualization Arts …

Computer Graphics Pipeline

Computer Graphics PipelineModeling

Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

Computer Graphics Pipeline : Modeling

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / DisplayObject space World space

原本在不同 object space 中的 model轉換至同一座標系 (world space)

Transformation example: Translation, Scaling, Rotation, Projection, 或者以上的綜合

Computer Graphics Pipeline : Illumination

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

根據材料性質、物體表面性質以及光源性質來實作

Local lighting model example: Diffuse, Ambient, Phong…

Computer Graphics Pipeline : Transformation

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

World space

Eye space

將 world space 對應到 eye space 通常將 viewing position 對應到 eye s

pace 的原點

將視角之外的物件部份消除掉 類似窗戶跟景物的關係

可節省系統運算資源 Several clipping algorithms have bee

n devised Hidden Surface Removal Problem

Computer Graphics Pipeline : Clipping

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

Computer Graphics Pipeline : Projection

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

Screen Space

將在 eye space 中 3D 的物件轉換至2D 的 screen space 上

Eye space

Computer Graphics Pipeline : Rasterization

Modeling Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

將物件影像像素化 插入顏色、深度等變數

Computer Graphics Pipeline : DisplayModeling

Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

三種主要輸出裝置： Monitors (CRT) Flat Panel Display (LCD, plasma) Hard Copy

兩個主要考慮的問題 色彩校準 人的相對亮度感覺

經過多次的 transformation…Modeling

Transformations

Illumination(Shading)

Viewing Transformation(Perspective / Orthographic)

Clipping

Projection (to Screen Space)

Scan Conversion(Rasterization)

Visibility / Display

Object space

World space

Eye Space / Camera Space

Screen Space

Computer Animation

Introduction to computer animation Keyframing Procedural animation Motion capture

Keyframing Draw key frames Tweening

Filling in-betweens Frames/sec depending on s

peed of movements

Keyframing

Linear Interpolation Non-linear Interpolation Others

Linear Interpolation Non-linear Interpolation

Procedural Animation

使用複雜的演算法來達成動畫效果 Example

Special effects: explosions, water, particles… Visualization

可重複使用 精確度較 keyframing 高

Motion Capture

Application Movies Games Virtual Reality

Motion CaptureActors wearing sensors

Tracking camera ?

Sampling

Processing

Output

example example2

Motion Capture

Types of sensors EM position and orientation sensor

Require a wire to each sensor Limited working volume Readings can be distorted by EM fields

Ultrasonic rangefinder triangulation Cheaper but less accurate

Optical triangulation Reflective or emissive markers attached to objects Two cameras triangulate position

triangulation

Motion Capture: The Processing StageReconstruction Labeling Editing

Actorisation Characterization Post-animation

Motion Capture

Advantage Exactly animate human movements Can capture secondary animation Can capture difficult-to-model physical movement

(ex. 雙截棍 ) Allow one actor to play multiple role in a film

Motion Capture

Disadvantage Noise!!! Magnetic system interference Difficult to manipulate the data after capturing &

processing Expensive Difficult to cooperate with cartoon models

Computer Animation: Future

The old vs. the new

The end

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