Ray Tracing Intro Steve Marschner CS 4620 Cornell University - - PowerPoint PPT Presentation

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Ray Tracing Intro Steve Marschner CS 4620 Cornell University - - PowerPoint PPT Presentation

Dec 17, 2023 389 likes •553 views

Ray Tracing Intro Steve Marschner CS 4620 Cornell University Cornell CS4620 Fall 2020 Steve Marschner 1 Projection To render an image of a 3D scene, we project it onto a plane Most common projection type is perspective projection

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SLIDE 1

Steve Marschner CS 4620 Cornell University

Steve Marschner • Cornell CS4620 Fall 2020

Ray Tracing Intro

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  • To render an image of a 3D scene, we project it onto a plane
  • Most common projection type is perspective projection

Steve Marschner • Cornell CS4620 Fall 2020

Projection

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SLIDE 3

Steve Marschner • Cornell CS4620 Fall 2020

Two approaches to rendering

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Steve Marschner • Cornell CS4620 Fall 2020

Two approaches to rendering

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for each object in the scene { for each pixel in the image { if (object affects pixel) { do something } } }

  • bject order
  • r

rasterization

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SLIDE 5

Steve Marschner • Cornell CS4620 Fall 2020

Two approaches to rendering

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for each object in the scene { for each pixel in the image { if (object affects pixel) { do something } } }

  • bject order
  • r

rasterization image order

  • r

ray tracing for each pixel in the image { for each object in the scene { if (object affects pixel) { do something } } }

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SLIDE 6

Steve Marschner • Cornell CS4620 Fall 2020

Two approaches to rendering

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for each object in the scene { for each pixel in the image { if (object affects pixel) { do something } } }

  • bject order
  • r

rasterization image order

  • r

ray tracing for each pixel in the image { for each object in the scene { if (object affects pixel) { do something } } } We will do this first

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SLIDE 7
  • Start with a pixel—what belongs at that pixel?
  • Set of points that project to a point in the image: a ray

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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SLIDE 8
  • Start with a pixel—what belongs at that pixel?
  • Set of points that project to a point in the image: a ray

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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SLIDE 9

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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SLIDE 10

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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SLIDE 11

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing idea

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SLIDE 13

Steve Marschner • Cornell CS4620 Fall 2020

Ray tracing algorithm

for each pixel { compute viewing ray intersect ray with scene compute illumination at visible point put result into image }

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  • inputs:

– camera parameters – a point in the image

  • outputs:

– a viewing ray

Steve Marschner • Cornell CS4620 Fall 2020

Eye ray generation

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viewing ray pixel position viewing window viewpoint

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SLIDE 15
  • inputs:

– list of objects in the scene – a ray

  • outputs:

– whether ray intersects anything – parameter of first intersection – information about surface

t

Steve Marschner • Cornell CS4620 Fall 2020

Ray intersection

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  • inputs:

– eye direction – light direction (for each of many lights) – surface normal – surface parameters (color, roughness, …)

  • outputs:

– light reflected towards eye

Steve Marschner • Cornell CS4620 Fall 2020

Shading

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