Ray tracing Flashcards

Lecture 11 (14 cards)

1
Q

What is the main difference between rasterization and ray tracing?

A
  • Rasterization: processes each object, then each pixel it covers
  • Ray tracing: processes each pixel, then checks all objects in that direction
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2
Q

How does rasterization handle visibility?

A

It uses a depth buffer to keep the closest fragment for each pixel

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3
Q

How does ray tracing handle visibility?

A

It casts a ray per pixel and keeps the closest object hit by that ray

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4
Q

How do lighting and shadows differ in rasterization and ray tracing?

A
  • Rasterization: estimates lighting using formulas; shadows need hacks (like shadow maps)
  • Ray tracing: simulates lighting with real ray bounces and handles shadows naturally
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5
Q

What is a key similarity between ray tracing and ray marching?

A

Both start by casting a ray from each pixel into the scene

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6
Q

What is the main difference in how rays are processed between ray tracing and ray marching?

A
  • Ray marching: takes many small steps using distances from SDFs
  • Ray tracing: directly checks for ray-object intersections and can bounce rays recursively
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7
Q

What kind of scene definition does ray marching use?

A

A Signed Distance Field: a function that returns the shortest distance from a point to the nearest surface.

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8
Q

What kind of scene definition does ray tracing use?

A

An intersection function: returns the closest surface hit along a ray direction.

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9
Q

What is a BVH?

A

A Bounding Volume HierArchy is a tree of bounding boxes around groups of objects, used to speed up intersection tests.

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10
Q

Why is a BVH useful for ray tracing?

A

It avoids testing the ray against every single object, reducing computations.

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11
Q

How is a BVH constructed?

A
  • Objects are wrapped in bounding boxes
  • These are grouped recursively into parent nodes
  • Each parent node contains the bounds of all its children
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12
Q

How is a BVH used during ray tracing?

A
  • Rays are tested against the BVH root
  • if a node is hit, its children are tested
  • The process repeats until leaf nodes (actual geometry) are reached
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13
Q

What are the main benefits of ray tracing?

A
  • Better reflections (can show things off-screen)
  • Better shadows (soft, transparent, no resolution limits)
  • Better transparency and refraction (no need for sorting)
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14
Q

What are the limitations of ray tracing?

A
  • Must test collisions with all (or many) objects
  • Complexity grows fast with recursive rays
  • Needs many rays for good quality -> leads to noise and high performance cost
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