PPT Slide

Building Curves

• Okay now we know how to represent curves

• But how to we specify them?

• Building blocks for a useful smooth curve:
  • flexible, springy line
  • definable points for it to pass through (control points)

• Draftsmen used such building blocks for plane curves
  • weights called ducks to hold down a thin flexible strip called a spline
  • ducks are placed at points the curve is supposed to pass through, and the springiness makes the spline fill in smoothly
  • The final curve is traced onto paper

• How to define this mathematically?

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