Raytracing -Computer Graphics

CS123 | INTRODUCTION TO COMPUTER GRAPHICS

Whitted 1980

Ray Tracing
Rendering and Techniques

Andries van Dam

November 4, 2010

http://cg.alexandra.dk/2009/08/10/triers-cuda-ray-tracing-tutorial/

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CS123 | INTRODUCTION TO COMPUTER GRAPHICS

Reading
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See Chapter 7, 15 in the book

Rendered with nVidia Iray

Andries van Dam

November 4, 2010

http://www.3dfocus.co.uk/wp-content/uploads/2011/03/ray-tracing-d.jpg 2

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CS123 | INTRODUCTION TO COMPUTER GRAPHICS

Introduction
What “effects” do you see?

red mirror

“soft” illumination changes
green mirror soft shadow?
No, but looks close due to complex scene and multiple light sources
rendered in a matter of seconds with Travis Fischer’s ’09 ray tracer

Andries van Dam

November 4, 2010

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CS123 | INTRODUCTION TO COMPUTER GRAPHICS

Origins of Ray Tracing
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Generalizing from Durer’s wood cut showing perspective projection

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Durer: Record string intersection from center of projection(eye) to the object as points on a 2D plane Points created are perspective projection of 3D object onto 2D plane
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Andries van Dam

CS123 | INTRODUCTION TO COMPUTER GRAPHICS

What is a Raytracer?
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A raytracer is a finite back mapping of rays from camera(eye) through each sample (pixel) to objects in scene Each pixel represents either:  ray intersection with an object in the scene  no intersection A ray traced scene is a “virtual photo” comprised of many samples on film plane

Eye

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Instead of one ray, imagine thousands of rays being shot from the eye through different points on film plane
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Andries van Dam

CS123 | INTRODUCTION TO COMPUTER GRAPHICS

Ray Tracing Fundamentals
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Generate primary ray
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shoot ray from the eye through a sample point on film plane sample point often is center of a pixel, but we can also supersample each pixel (see slide 34 in image... [continues]

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