Quantifying the Error of Light Transport Algorithms

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2019-07-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
11
111-121
Series
Computer Graphics Forum, Volume 38, issue 4
Abstract
This paper proposes a new methodology for measuring the error of unbiased physically based rendering algorithms. The current state of the art includes mean squared error (MSE) based metrics and visual comparisons of equal-time renderings of competing algorithms. Neither is satisfying as MSE does not describe behavior and can exhibit significant variance, and visual comparisons are inherently subjective. Our contribution is two-fold: First, we propose to compute many short renderings instead of a single long run and use the short renderings to estimate MSE expectation and variance as well as per-pixel standard deviation. An algorithm that achieves good results in most runs, but with occasional outliers is essentially unreliable, which we wish to quantify numerically. We use per-pixel standard deviation to identify problematic lighting effects of rendering algorithms. The second contribution is the error spectrum ensemble (ESE), a tool for measuring the distribution of error over frequencies. The ESE serves twopurposes: It reveals correlation between pixels and can be used to detect outliers, which offset the amount of error substantially.
Description
Keywords
CCS Concepts, • Computing methodologies → Ray tracing
Other note
Citation
Celarek , A , Jakob , W , Wimmer , M & Lehtinen , J 2019 , ' Quantifying the Error of Light Transport Algorithms ' , Computer Graphics Forum , vol. 38 , no. 4 , pp. 111-121 . https://doi.org/10.1111/cgf.13775