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WELCOME! TODAYS TOPICS: SOFT SHADOWS GLASS GP1 – Ray Tracing Recap In 3D, light falls Angle also plays a role: off with distance: 2 Iin = IL / r Iin *= dot(L,N) And finally, material color. GP1 – Ray Tracing Homework GP1 – Ray Tracing GP1 – Ray Tracing Caustic(?) Dielectric(?) Shadow Sphere Plane N Quadratic falloff Reflection B T P∙T - O∙T = fx u . scale P∙B - O∙B = fy v . shift P = O + fx * T + fy * B . modulo GP1 – Ray Tracing Dielectrics: reflect and transmit 1. Reflection: RR = Reflect( D, N ); 2. Transmittance: RT = ? 3. Ratio between the two: return ? * Trace(RR) + ? * Trace(RT) nt = index/1, nnt = 1 / index, ddn = D∙N cos2t = 1 – nnt2 * (1 – ddn2) cos2t <= 0 ? TIR Snell 2 RT = normalize( D * nnt – N * (ddn * nnt * sqrt( cos t )) ); v = (nt - 1)2/(nt + 1)2 Fresnel 5 WT = v + (1 - v) * (1 + ddn) , WR = 1 – WT Schlick N GP1 – Ray Tracing Christopher Schlick Willebrord Snel Augustin-Jean Fresnel GP1 – Ray Tracing SO SHA FT DOW GP1 – Ray Tracing GP1 – Ray Tracing 25% 33.3% GP1 – Ray Tracing GP1 – Ray Tracing GP1 – Ray Tracing GP1 – Ray Tracing Soft shadows: . Approximated using N random rays . That means we get noise . More rays, less noise . Reduce variance: stratification . Reduce variance: converging GP1 – Ray Tracing Other applications of randomness: Anti-aliasing: send rays to random position on pixel fx = x / SCRWIDTH fx = (x + rand()) / SCRWIDTH Depth of field: send rays from random position on lens O += float3( rand() – 0.5f, rand() – 0.5f, rand() – 0.5f ) Motion blur: send rays to object at random time t = frameTime + rand() Dispersion: randomly pick wavelength for primary ray λ = rand() Use a high-quality random generator to prevent patterns: MERSENNE TWISTER GP1 – Ray Tracing Other applications of randomness: Homework Implement glass 1. Make sure your reflections are working 2. Make sure you have N dot L and 1/r^2 shading 3. Modify Renderer::Trace Next week: DEPTH OF FIELD ACCELERATION STRUCTURE.

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Classical and Modern Diffraction Theory
Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Classical and Modern Diffraction Theory Edited by Kamill Klem-Musatov Henning C. Hoeber Tijmen Jan Moser Michael A. Pelissier SEG Geophysics Reprint Series No. 29 Sergey Fomel, managing editor Evgeny Landa, volume editor Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Society of Exploration Geophysicists 8801 S. Yale, Ste. 500 Tulsa, OK 74137-3575 U.S.A. # 2016 by Society of Exploration Geophysicists All rights reserved. This book or parts hereof may not be reproduced in any form without permission in writing from the publisher. Published 2016 Printed in the United States of America ISBN 978-1-931830-00-6 (Series) ISBN 978-1-56080-322-5 (Volume) Library of Congress Control Number: 2015951229 Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Dedication We dedicate this volume to the memory Dr. Kamill Klem-Musatov. In reading this volume, you will ﬁnd that the history of diffraction We worked with Kamill over a period of several years to compile theory was ﬁlled with many controversies and feuds as new theories this volume. This volume was virtually ready for publication when came to displace or revise previous ones. Kamill Klem-Musatov’s Kamill passed away. He is greatly missed. new theory also met opposition; he paid a great personal price in Kamill’s role in Classical and Modern Diffraction Theory goes putting forth his theory for the seismic diffraction forward problem.
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