Barycentric Coordinates

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Barycentric Coordinates

• Position on plane of triangle (u, v, w)
• P(u, v, w) au bv cw (where a, b, c are
  locations of vertices.
• u v w 1
• 2 coords 0 ? vertex
• 1 coord 0 ? edge

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Barycentric Coordinates

• If any coordinate is lt 0 or gt 1, point is outside
  triangle

3
Barycentric Coordinates

• u Aa / A where A is area of complete triangle
• v Ab / A
• w Ac / A

B
Aa
Ac
Ab
C
A
4
Stochastic Ray Tracing

• Antialiasing
• Gloss distribute reflected rays
• Blurred transparency distribute transmitted
  rays
• Soft shadows distribute light rays (to an area
  source)
• Depth of field distributing locations over lens
• Motion blur (moving object or moving camera)
  distributing rays over time

5
Gloss

• Instead of just a simple reflected ray, shoot
  more and perturb them.
• This will take surface from mirror-like

6
Transparency

• Same thing, perturb ray
• May also want to try textured transparency
• Look up a texture map that describes the
  transparency (or properties) of the surface.
• Screen-door transparency

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Soft Shadows

• Area light sources
• Shoot shadow rays to points on light
• Cook suggests distributing rays over light based
  on brightness of areas of light
• Use projected area to weight rays

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Camera Models

• Pinhole ideal camera
• All rays go through single point
• Everything in focus -- unrealistic

9
More Realistic Model

• Lenses with spherical surfaces
• Why?

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