Basics

Ray Tracing:

Photorealism - The Holy Grail

• Want to make more realistic images
  • Shadows
  • Reflections
• What happens in the real world?

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  Problem: Many rays never reach the eye.

• Idea: Trace rays backwards

  

Ray Tracing:

Basic Code

foreach pixel
    ray = (eye, pixel-eye);
    Intersect(Scene, ray);
end

Issues:

• Which pixels?
• How do we perform intersections?
• How do we perform shading?
• How can we speed things up?
• How can we make things look better?

Ray Tracing/Casting:

Selecting the initial ray

• Setting: eyepoint, virtual screen (an array of virtual pixels, and scene are organized in convenient coordinate frames (e.g. all in view or world frames)
• Ray: a half line determined by the eyepoint and a point associated with a chosen pixel
• Interpretations:
  • Ray is the path of photons that succesfully reach the eye
    (we simulate selected photon transport through the scene)
  • Ray is a sampling probe that gathers color/visibility information

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Readings: Red book, 14.7; White book, 16.12.