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Fast Hierarchical Importance Sampling with Blue Noise Properties. Victor Ostromoukhov University of Montreal. Charles Donohue University of Montreal. Pierre-Marc Jodoin University of Montreal. Presented By: Ryan Overbeck. Goal. To QUICKLY generate a GOOD point sample distribution.
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Fast Hierarchical Importance Sampling with Blue Noise Properties Victor Ostromoukhov University of Montreal Charles Donohue University of Montreal Pierre-Marc Jodoin University of Montreal Presented By: Ryan Overbeck
Goal • To QUICKLY generate a GOOD point sample distribution.
Motivation NPR -- Stippling Environment Map Sampling Image Anti-aliasing [Agarwal et al. 2003] [Kopf et al. 2006] [Taken from CDRinfo: http://www.cdrinfo.com/]
Good == Blue Noise? • In English: • We want a set of samples that are random but regularly spaced! • In Fourier: • Low angular anisotropy • Low energy annulus about the DC spike • High energy annulus • mean distance between samples • Medium energy background
Blue Noise? • Low angular anisotropy => Radially evenly random • Low energy annulus about the DC spike => Aperiodic • High energy annulus => Adjustable mean distance • Medium magnitude background => Spatially evenly random Samples Fourier Images from Dunbar et al. 06
Solution: • Use Penrose Tiling to provide sample distribution • Kinda Random • Aperiodic • Multi-resolution
Stuff I’m Glossing Over • F-codes and Structural Indices • Heuristic for subdivision • Lookup Table-based Relaxation • Improves the spatial distribution of the sampling points.
Example Penrose Fourier Analysis Ideal Blue Noise Fourier
Results LightGen Structured Importance Penrose Distributions using 300 Samples 45 minutes 25 Seconds 8 milliseconds Images rendered using above distributions
Conclusion • Penrose Tiling can quickly generate a hierarchical point sample distribution that is “random” and regularly spaced. • Blue Noise == Random and regularly spaced.