MC Ray Tracing: Part II, Importance Sampling Sung-Eui Yoon ( ) - PowerPoint PPT Presentation

CS580: MC Ray Tracing: Part II, Importance Sampling Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/GCG

Class Objectives: ● I mportance sampling for: ● Direct terms ● Lights ● I ndirect terms 2

Performance and Error ● Want better quality with smaller number of samples ● Fewer samples  better performance ● Stratified sampling ● Quasi Monte Carlo: well-distributed samples ● Faster convergence ● I mportance sampling: next-event estimation 3

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Importance Sampling 6

Importance Sampling 7

Comparison From kavita’s slides ● With and without considering direct illumination ● 16 samples / pixel 8

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From kavita’s slides Anti-aliasing 22

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Do not take visibility into account! 24

Research on Many Lights ● Ward 91 ● Sort lights based on their maximum contribution ● Pick bright lights based on a threshold ● Do not consider visibility ● Many other papers ● One of recent works: ● LightCuts: A Scalable Approach to I llumination, SI G. 05, Walter et al. 25

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y  z  x 30

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General GI Algorithm ● Design path generators ● Path generators determine efficiency of GI algorithm ● Black boxes ● Evaluate BRDF, ray intersection, visibility evaluations, etc 42

Class Objectives were: ● I mportance sampling for: ● Direct terms ● Lights ● I ndirect terms 43