Shadow Algorithms Data Miner [Woo & Poulin 2012-06-12]

Shadow Algorithms Data Miner Shadow Algorithms Data Miner Andrew Woo Pierre Poulin Cover image: “City View,” by Kumi Yamashita Used by permission CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2012 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S Government works Printed in the United States of America on acid-free paper Version Date: 20120123 International Standard Book Number: 978-1-4398-8023-4 (Hardback) This book contains information obtained from authentic and highly regarded sources Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to 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Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe Library of Congress Cataloging‑in‑Publication Data Woo, Andrew, 1965‑ Shadow algorithms data miner / Andrew Woo, Pierre Poulin p cm “An A K Peters Book.” Summary: “Digital shadow generation continues to be an important aspect of visualization and visual effects in film, games, simulations, and scientific applications This resource offers a thorough picture of the motivations, complexities, and categorized algorithms available to generate digital shadows From general fundamentals to specific applications, it addresses “out of core” shadow algorithms and how to manage huge data sets from a shadow perspective The book also examines the use of shadow algorithms in industrial applications, in terms of what algorithms are used and what software is applicable “‑‑ Provided by publisher Includes bibliographical references and index ISBN 978‑1‑4398‑8023‑4 (hardback) Graph algorithms Data mining Computer graphics I Poulin, Pierre, 1964‑ II Title QA166.245.W66 2012 006.6’93‑‑dc23 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com 2011047828 To Cynthia, Marcus, Eric, Alice, Carson, and Shirley —Andrew Woo ` et Robert A` Th´erese —Pierre Poulin Contents Preliminaries of Shadows 1.1 What’s Covered in This Chapter 1.2 Basic Concepts 1.2.1 Why Shadows 1.2.2 Hard Shadows versus Soft Shadows 1.2.3 Colored Shadows 1.3 Shadow Algorithms: Basic Ideas and Properties 1.3.1 Planar Receivers of Shadows 1.3.2 Shadow Depth Map 1.3.3 Shadow Volumes 1.3.4 Ray Tracing 1.3.5 Area Subdivision and Preprocessing 1.4 Self-Shadowing ˆ ⋅ Lˆ Check 1.4.1 N 1.4.2 Bump Mapping 1.4.3 Advanced Reflection Models 1.5 Considerations for Choosing an Algorithm 1 1 8 12 15 16 18 18 20 21 21 Hard Shadows 2.1 What’s Covered in This Chapter 2.2 Planar Receivers of Shadows 2.3 Shadow Depth Maps 2.3.1 Dealing with Different Light Types 2.3.2 Performance Considerations 2.3.3 Quality Considerations 2.3.4 Avoiding Bad Self-Shadowing Problems 2.3.5 Filtering Considerations 2.3.6 Combining Self-Shadowing and Filtering 2.3.7 Focusing the Resolution 25 25 25 27 27 28 33 34 38 39 43 vii viii Contents 2.4 2.5 2.6 2.7 Shadow Volumes 2.4.1 Shadow Volumes on the CPU 2.4.2 Shadow Volumes on the GPU 2.4.3 Reducing the Complexity 2.4.4 Shadow Volumes Integrating BSP Trees Ray Tracing 2.5.1 Shadow Culling Algorithms 2.5.2 Combining Ray Packing and Modern Architectures 2.5.3 Dealing with Many Lights 2.5.4 Antialiased Shadows Other Hard Shadow Algorithms Trends and Analysis 2.7.1 Offline Rendering Trends 2.7.2 Real-Time Rendering Trends 2.7.3 General Comments Supporting Shadows for Other Geometry Types 3.1 What’s Covered in This Chapter 3.2 Higher-Order Surfaces 3.2.1 Numerical Iteration 3.2.2 Polygonization 3.2.3 Shadow Volumes 3.2.4 Trends and Analysis 3.3 Image-Based Rendering for Impostors 3.3.1 Trees 3.3.2 Crowds 3.3.3 Trends and Analysis 3.4 Geometry Images 3.4.1 Trends and Analysis 3.5 Particle Systems 3.6 Point Clouds 3.6.1 Shadow Depth Map 3.6.2 Ray Tracing 3.6.3 Other Miscellaneous Techniques 3.6.4 Trends and Analysis 3.7 Voxels 3.7.1 Splatting 3.7.2 Shear-Warp 3.7.3 Slice-Based Hardware Textures 3.7.4 Ray Tracing 3.7.5 Shadow Depth Map 3.7.6 Trends and Analysis 53 54 55 59 62 63 64 66 67 69 69 70 70 71 72 75 75 76 77 78 79 79 80 81 82 83 84 85 85 85 87 88 88 89 89 91 92 93 93 95 96 Contents 3.8 ix 97 98 99 100 100 Soft Shadows 4.1 What’s Covered in This Chapter 4.2 Soft Shadow Basics 4.2.1 Computing the Soft Shadow Integral 4.2.2 Generic Algorithmic Approaches 4.3 Theoretical Aspects 4.3.1 Discontinuity Events 4.4 Planar Receivers of Shadows 4.4.1 Soft Shadow Textures 4.4.2 Plateau Shadows 4.4.3 Convolution Textures 4.5 Shadow Depth Maps 4.5.1 Z-Difference Penumbra Approximation 4.5.2 Depth Values as Micropatches 4.5.3 Silhouette Detection-Based Solutions 4.5.4 Multipoint Source Shadow Depth Map Algorithms 4.5.5 Rendering Large Scenes 4.5.6 Other Shadow Depth Map Variations 4.6 Shadow Volumes 4.6.1 Multipoint Shadow Volumes 4.6.2 Shadow Volume BSP (SVBSP) 4.6.3 Penumbra Wedges 4.7 Ray Tracing 4.7.1 Distribution Ray Tracing 4.7.2 Structures for Exact Back-Projection 4.7.3 Single-Ray Analytic Solution 4.7.4 Ray Tracing Depth Images 4.8 Other Soft Shadow Algorithms 4.9 Trends and Analysis 4.9.1 Offline Rendering Trends 4.9.2 Real-Time Rendering Trends 4.9.3 General Comments 3.9 Heightfields 3.8.1 Ray Tracing 3.8.2 Horizon Mapping 3.8.3 Trends and Analysis Final Words 101 101 102 102 105 107 108 111 112 112 113 114 114 116 119 123 124 126 127 127 128 128 130 131 133 136 137 139 139 140 140 140 x Other Treatments of Shadows 5.1 What’s Covered in This Chapter 5.2 Bump Mapping 5.2.1 Advanced Bump Mapping Effects 5.2.2 Trends and Analysis 5.3 Advanced Reflection Models 5.3.1 Trends and Analysis 5.4 Semitransparent Surfaces 5.4.1 Ray Tracing 5.4.2 Shadow Maps 5.4.3 Shadow Volumes 5.4.4 Trends and Analysis 5.5 Highly Complex Thin Materials 5.5.1 Trends and Analysis 5.6 Atmospheric Shadows 5.6.1 Shadow Volumes 5.6.2 Shadow Depth Maps 5.6.3 Global Illumination 5.6.4 Trends and Analysis 5.7 Motion Blur 5.7.1 Trends and Analysis 5.8 Ambient Occlusion 5.8.1 Related Concepts 5.8.2 Representation 5.8.3 Object-Space Methods 5.8.4 Screen-Space Methods 5.8.5 Animation 5.8.6 Trends and Analysis 5.9 Precomputed Radiance Transfer 5.9.1 Trends and Analysis 5.10 Global Illumination 5.10.1 Radiosity 5.10.2 Virtual Point Lights 5.10.3 Monte Carlo Ray Tracing 5.10.4 Trends and Analysis 5.11 Final Words Contents 143 143 144 146 147 147 150 151 151 152 154 155 155 157 157 158 159 161 161 161 163 163 164 164 166 168 170 171 171 174 174 175 177 178 179 180 Applications of Shadow Algorithms 6.1 What’s Covered in This Chapter 6.2 Augmented Reality 6.2.1 Augmented Reality Assuming Direct Illumination 6.2.2 Augmented Reality for Global Illumination 181 181 181 182 184 Contents 6.3 6.4 6.5 xi 6.2.3 Model Reconstruction Techniques 6.2.4 Trends and Analysis Non-photorealistic Environments 6.3.1 Pen and Ink 6.3.2 Technical Illustration 6.3.3 Cartoon Rendering 6.3.4 Trends and Analysis Shadows as Interaction Tools 6.4.1 Trends and Analysis Final Words 185 185 186 186 187 188 190 190 191 191 Conclusions 193 Bibliography 197 Index 239 .. .Shadow Algorithms Data Miner Shadow Algorithms Data Miner Andrew Woo Pierre Poulin Cover image: “City View,” by Kumi Yamashita Used by permission CRC Press Taylor & Francis Group... Congress Cataloging‑in‑Publication Data Woo, Andrew, 1965‑ Shadow algorithms data miner / Andrew Woo, Pierre Poulin p cm “An A K Peters Book.” Summary: “Digital shadow generation continues to be... categorized algorithms available to generate digital shadows From general fundamentals to specific applications, it addresses “out of core” shadow algorithms and how to manage huge data sets from a shadow