Introduction and Graphics Pipeline

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Introduction and Graphics Pipeline

• Advanced Multimedia Technology Computer Graphics
• Yung-Yu Chuang
• 2005/12/07

with slides by Brian Curless, Zoran Popovic,
Robin Chen and Doug James
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Introduction

• Instructor Yung-Yu Chuang (???)
• E-mail cyy_at_csie.ntu.edu.tw
• Office CSIE 527
• Web
• http//www.csie.ntu.edu.tw/cyy/amt/

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What is Computer Graphics ?

• Definition
• the pictorial synthesis of real or imaginary
  objects from their computer-based models

OUTPUT
descriptions images
descriptions Computer Graphics
images Computer Vision Image Processing
INPUT
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Computer graphics

• Create a 2D image/animation of a 3D world

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Computer graphics
modeling
rendering
animation
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Applications

• Movies
• Interactive entertainment
• Industrial design
• Architecture
• Culture heritage

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Animation production pipeline
storyboard
story
text treatment
voice
storyreal
look and feel
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Animation production pipeline
animation
layout
modeling/articulation
shading/lighting
rendering
final touch
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Scan converting lines

• A scan-converted line showing intensified pixels
  as black circles

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The basic incremental algorithm
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The basic incremental algorithm

• void Line (int x0, int y0, int x1, int y1, value)
  
• int x
• float dy, dx, y, m
• dyy1-y0
• dxx1-x0
• mdy/dx
• yy0
• for (xx0 xltx1 x)
• WritePixel (x, (int)floor(y0.5), value)
• ym

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Filling Polygons
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Filling Polygons
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Filling Polygons

1. find the intersections of the scan line with all
   edges of the polygon
2. sort the intersections by increasing x coordinate
3. fill in all pixels between pairs of intersections
   that lie interior to the polygon

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Transformations
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Representation
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Representation
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2D transformations
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Identity
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Scaling
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Scaling
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Reflection
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Shearing
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Transformation of a unit square
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Transformation of a unit square
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Rotation
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Limitations of a 2X2 matrix

• Scaling
• Rotation
• Reflection
• Shearing
• What do we miss?

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Homogeneous coordinate
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Translation
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3D scaling
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3D translation
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3D rotation
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3D shearing
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Graphics pipeline
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Graphics pipeline
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3D synthetic camera model
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Imaging with the synthetic camera
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Specifying a viewer
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Projections
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Parallel and perspective projections
orthographic
perspective
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Orthographic transformation
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Perspective projection
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Perspective transform
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Visibility Algorithms

• Painters algorithm
• Ray casting
• Z-buffer
• Binary space partitioning

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Ray casting
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Z-buffer algorithm
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Z-buffer algorithm
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Z-buffer algorithm
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Binary space partition
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BSP tree
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BSP tree construction
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BSP tree display
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Back face culling