Practical Global Illumination with Irradiance Caching (Synthesis Lectures on Computer Graphics and Animation)

✍ Scribed by Jaroslav Krivanek, Pascal Gautron

• Publisher: Morgan & Claypool
• Year: 2009
• Tongue: English
• Leaves: 148
• Series: SYNTHESIS LECTURES ON COMPUTER GRAPHICS AND ANIMATION
• Category: Library

✦ Synopsis

Irradiance caching is a ray tracing-based technique for computing global illumination on diffuse surfaces. Specifically, it addresses the computation of indirect illumination bouncing off one diffuse object onto another. The sole purpose of irradiance caching is to make this computation reasonably fast. The main idea is to perform the indirect illumination sampling only at a selected set of locations in the scene, store the results in a cache, and reuse the cached value at other points through fast interpolation. This book is for anyone interested in making a production-ready implementation of irradiance caching that reliably renders artifact-free images. Since its invention 20 years ago, the irradiance caching algorithm has been successfully used to accelerate global illumination computation in the Radiance lighting simulation system. Its widespread use had to wait until computers became fast enough to consider global illumination in film production rendering. Since then, its use is ubiquitous. Virtually all commercial and open-source rendering software base the global illumination computation upon irradiance caching. Although elegant and powerful, the algorithm in its basic form often fails to produce artifact-free mages. Unfortunately, practical information on implementing the algorithm is scarce. The main objective of this book is to show the irradiance caching algorithm along with all the details and tricks upon which the success of its practical implementation is dependent. In addition, we discuss some extensions of the basic algorithm, such as a GPU implementation for interactive global illumination computation and temporal caching that exploits temporal coherence to suppress flickering in animations. Our goal is to show the material without being overly theoretical. However, the reader should have some basic understanding of rendering concepts, ray tracing in particular. Familiarity with global illumination is useful but not necessary to read this book. Table of Contents: Introduction to Ray Tracing and Global Illumination / Irradiance Caching Core / Practical Rendering with Irradiance Caching / Irradiance Caching in a Complete Global Illumination / Irradiance Caching on Graphics Hardware / Temporal Irradiance Caching

✦ Table of Contents

Synthesis Lectures on Computer Graphics and Animation......Page 2
Contents......Page 7
Preface......Page 11
Basic Radiometric Quantities......Page 15
Rendering Goal: Find Radiance......Page 17
Shading, Reflectance, and the BRDF......Page 18
Direct Illumination......Page 23
Indirect Illumination......Page 24
Lambertian Reflection......Page 27
Rendering Equation......Page 30
Irradiance Caching Core......Page 31
Indirect Irradiance Calculation......Page 32
Irradiance Gradients......Page 35
Irradiance Caching Algorithm......Page 38
Interpolation......Page 41
Distance to Surfaces, Ri......Page 43
Data Structure......Page 52
Single-Reference Octree......Page 53
Multiple-Reference Octree......Page 54
Last Query Reuse......Page 55
Irradiance Caching Summary......Page 56
Hierarchical Refinement and Best Candidate Pattern......Page 57
Ray Tracing Simplified Geometry......Page 58
Bump Mapping......Page 60
Fur, Hair & Grass......Page 61
Motion Blur......Page 62
Ambient Occlusion Caching......Page 66
Irradiance Caching in a Complete Global Illumination Solution......Page 69
Illumination Components......Page 70
Smooth Diffuse Indirect Illumination......Page 71
Glossy indirect illumination......Page 72
Recursion......Page 76
Multiple Indirect Bounces Using Recursive Irradiance Caching......Page 78
Multiple Indirect Bounces Using Photon Mapping......Page 79
Irradiance Caching on Graphics Hardware......Page 85
Irradiance Splatting......Page 86
Cache Miss Detection......Page 88
Hemisphere Sampling on the GPU......Page 90
Irradiance Computation......Page 92
Irradiance Gradient Computation......Page 94
Global Illumination Rendering......Page 97
High Quality Rendering......Page 98
Interactive Global Illumination......Page 99
Conclusion......Page 101
Temporal Weighting Function......Page 105
Temporal Gradients......Page 107
Estimating Future Irradiance Et0+1......Page 109
GPU Implementation......Page 111
Results......Page 113
Conclusion......Page 117
Solid Angle......Page 119
Differential Solid Angle......Page 120
Spherical Integration......Page 121
Expected Value and Variance......Page 122
Monte Carlo Estimators......Page 123
Importance Sampling: A Variance Reduction Technique......Page 124
Translation Gradient Derivation......Page 127
Split-Sphere Model......Page 131
Primary Sources......Page 135
Further Reading on Irradiance Caching......Page 137
Background on Global Illumination......Page 138
Bibliography......Page 139
About the Authors......Page 143
Index......Page 145