Outline n n n History of computer graphics

Outline n n n History of computer graphics Computer graphics pipeline Introduction to animation

History 萌芽期 發展期 成熟期 (60’s~mid 70’s) (late 70’s~80’s) (90’s~00’s)

History n SAGE system, WWII q n Air defense system Dr. Ivan Sutherland (MIT), 1963 q q q Invent Sketchpad Interactive design on vector graphics The origin of computer graphics 萌芽期 發展期 成熟期 (60’s~mid 70’s) (late 70’s~80’s) (90’s~00’s)

History n First raster display, 1966 q q What is raster scan? Display or capture image line by line 萌芽期 發展期 成熟期 (60’s~mid 70’s) (late 70’s~80’s) (90’s~00’s)

History n Apple II, 1977 q q 帶起PC革命 彩色圖形介面 萌芽期 發展期 成熟期 (60’s~mid 70’s) (late 70’s~80’s) (90’s~00’s)

History n Toy Story, 1995, Pixar q q 第一部 3 D動畫長片 Woody跟Buzz Lightyear之間 的愛恨情仇 萌芽期 發展期 成熟期 (60’s~mid 70’s) (late 70’s~80’s) (90’s~00’s)

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

Computer Graphics Pipeline

Computer Graphics Pipeline Modeling Transformations Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display

Computer Graphics Pipeline : Modeling Transformations Illumination (Shading) Viewing Transformation (Perspective / Orthographic) n n 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 Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display Object space World space

Computer Graphics Pipeline : Illumination Modeling Transformations Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display n n 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) n n 將world space對應到eye space 通常將viewing position對應到eye space的原點 Viewing Transformation (Perspective / Orthographic) Eye space Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display World space

Computer Graphics Pipeline : Clipping Modeling Transformations n 將視角之外的物件部份消除掉 q 類似窗戶跟景物的關係 Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display n n n 可節省系統運算資源 Several clipping algorithms have been devised Hidden Surface Removal Problem

Computer Graphics Pipeline : Projection Modeling Transformations Illumination (Shading) n 將在eye space中 3 D的物件轉換至 2 D 的screen space上 Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display Eye space Screen Space

Computer Graphics Pipeline : Rasterization Modeling Transformations Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display n n 將物件影像像素化 插入顏色、深度等變數

Computer Graphics Pipeline : Display Modeling n 三種主要輸出裝置： Transformations q Illumination (Shading) Viewing Transformation (Perspective / Orthographic) q q n 兩個主要考慮的問題 Clipping q Projection (to Screen Space) q Scan Conversion (Rasterization) Visibility / Display Monitors (CRT) Flat Panel Display (LCD, plasma) Hard Copy 色彩校準 人的相對亮度感覺

經過多次的transformation… Modeling Transformations Object space Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion (Rasterization) Visibility / Display World space Eye Space / Camera Space Screen Space

Computer Animation

Introduction to computer animation n Keyframing Procedural animation Motion capture

Keyframing n n Draw key frames Tweening q q Filling in-betweens Frames/sec depending on speed of movements

Keyframing n n n Linear Interpolation Non-linear Interpolation Others Linear Interpolation Non-linear Interpolation

Procedural Animation n n 使用複雜的演算法來達成動畫效果 Example q q n n Special effects: explosions, water, particles… Visualization 可重複使用 精確度較keyframing高

Motion Capture n Application q q q Movies Games Virtual Reality

Motion Capture Actors wearing sensors Tracking camera ? Sampling Processing Output example 2

Motion Capture n Types of sensors q EM position and orientation sensor n n n q Ultrasonic rangefinder triangulation n q Require a wire to each sensor Limited working volume Readings can be distorted by EM fields triangulation Cheaper but less accurate Optical triangulation n n Reflective or emissive markers attached to objects Two cameras triangulate position

Motion Capture: The Processing Reconstruction Labeling Editing Stage Actorisation Characterization Post-animation

Motion Capture n Advantage q q 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 n Disadvantage q q q Noise!!! Magnetic system interference Difficult to manipulate the data after capturing & processing Expensive Difficult to cooperate with cartoon models

Computer Animation: Future n The old vs. the new

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