CIS 736 (Computer Graphics) Lecture 7 of 30

1
Lecture 7
Clipping Concluded Introduction to Curve
Representations
Wednesday, February 9, 2000 William H.
Hsu Department of Computing and Information
Sciences, KSU http//www.cis.ksu.edu/bhsu Readin
gs Sections 11.1, 11.2.1-11.2.2, Foley et
al (Reference) Appendix A.9, 6.7-6.11, 10.6-10.8,
Hearn and Baker 2e (Reference) 10.1-1.3,10.6,
Angel 2e
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Lecture Outline

• Readings
• Sections 11.1, 11.2.1-11.2.2, Foley et al
• Optional references Hearn and Baker 2e, Angel 2e
• Quick Review 3D Viewing
• 3D view volume
• ???
• Clipping (Concluded)
• ???
• ???
• ???
• Introduction to Curve Representations
• What are cubic curves?
• How would we use them to represent surfaces?
• Read about polygon meshes, Bézier curves,
  B-splines for next time!
• Next Lecture Cubic Curves and Surfaces

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Quick Review3D View Volume

• 3 Components
• Project proposal (20, 50 points)
• Implementation (50, 125 points)
• Final report (30, 75 points)
• Project Proposal (Due 02/14/2000)
• 1-3 page description of project topic, plan
• Guidelines next (suggested topics, tools to
  appear on CIS 736 course web page)
• See implementation practicum links (Brown,
  Cornell, UNC, others) on 736 page
• Implementation
• Students choice of programming language
• Guidelines next Wednesday (and on 736 page)
• Final Report
• 4-6 page report on implementation, experimental
  results, interpretation
• Peer-reviewed (does not determine grade)
• Reviews graded (short report worth 60 points,
  reviews worth 15 points)

4
Quick ReviewFrom Perspective to Parallel

• Perspective-to-Parallel Viewing Transformation
• ???
• ???
• ???
• Why Is This Important?
• ???
• ???
• ???
• ???
• ???
• ???
• ???
• ???
• Reviews graded (short report worth 60 points,
  reviews worth 15 points)

5
Clipping
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Clipping Lines 1Simultaneous Equations
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Clipping Lines 2Parametric Equations
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Clipping Polygons
9
Clipping Curves, Text, and Windows
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Clipping in 3D 1Extending Cohen-Sutherland
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Clipping in 3D 2Extending Liang-Barsky
12
Quick ReviewSpecifying an Arbitrary 3D View
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Intro to Curves
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Intro to Curves
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Course ProjectMore Guidelines

• 3 Components
• Project proposal (20, 50 points)
• Implementation (50, 125 points)
• Final report (30, 75 points)
• Project Proposal (Due 02/14/2000)
• 1-3 page description of project topic, plan
• Guidelines next (suggested topics, tools to
  appear on CIS 736 course web page)
• See implementation practicum links (Brown,
  Cornell, UNC, others) on 736 page
• Implementation
• Students choice of programming language
• Guidelines next Wednesday (and on 736 page)
• Final Report
• 4-6 page report on implementation, experimental
  results, interpretation
• Peer-reviewed (does not determine grade)
• Reviews graded (short report worth 60 points,
  reviews worth 15 points)

16
Course ProjectSuggested Topics

• 3 Components
• Project proposal (20, 50 points)
• Implementation (50, 125 points)
• Final report (30, 75 points)
• Project Proposal (Due 02/14/2000)
• 1-3 page description of project topic, plan
• Guidelines next (suggested topics, tools to
  appear on CIS 736 course web page)
• See implementation practicum links (Brown,
  Cornell, UNC, others) on 736 page
• Implementation
• Students choice of programming language
• Guidelines next Wednesday (and on 736 page)
• Final Report
• 4-6 page report on implementation, experimental
  results, interpretation
• Peer-reviewed (does not determine grade)
• Reviews graded (short report worth 60 points,
  reviews worth 15 points)

17
Terminology

• Review Normalizing Transformations
• Nper M Sper SHpar T(PRP) R T(VRP)
  (Equation 6.49, FVD)
• M
• Line Clipping Determining Parts of Line Segment
  Primitives to Display
• E
• Division of plane into 9 regions with (4-bit)
  outcodes
• Testing endpoints of line segment
• Parametric clipping line / rectangle
  intersection using parametric equation
• Cyrus-Beck general convex 3D polyhedron
• Liang-Barsky more efficient, specialized variant
  (upright 2D, 3D clip regions)
• Clipping in 3D
• Cuboid truncated viewing pyramid used to clip
  after Npar
• Frustum truncated viewing pyramid
• Cubic Curves

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Summary Points