15 - Ray Tracing

ucla | CS 174A | 2024-03-19 14:54

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Table of Contents

• Transmission and Reflected Rays
  • Direction of rays
  • Ray tree
• Performance
• Limitations
• Stochastic RT

Transmission and Reflected Rays

• recursive ray casting, we can decide recursive stack size
• at every intersetion, we have a relected ray AND a refracted ray called a transmission ray
• we can illluminate these points based on the the r,t rays
• these reflected rays are secondary rays and an spawn more reflected rays and transmission rays with other objets

  Direction of rays

• derived from real world

  Ray tree

• we can create a ray tree baed on secondary rays
• we also consider shadow rays

  Performance

  

Limitations

• Surface “acne” from numerial precision of rays being off and misclassifying a point as in shadow -> a dark spot on the surface of the objet
• backward ray tracing means that if there is a refractive material ffrom the intersection point of an object to the LIGHT
  • then that point should actually be refracted in forward tracing, but bc we do back tracing, we’re not able to do that
• aliasing isues usually happn when camera is far from objects bc rays diverge bw each pixel
  • spatial aliasing - overlapping object
  • temporal aliasing - object moves over time and may pop in and out bc rays miss
  • fix both by increasing sampling of rays
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Stochastic RT

• fixes many problems b ut requires many ray samples per pixel