Quantifying the Error of Light Transport Algorithms

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2019-07-01

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Mcode

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Language

en

Pages

11

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Computer Graphics Forum, Volume 38, issue 4, pp. 111-121

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 two purposes: It reveals correlation between pixels and can be used to detect outliers, which offset the amount of error substantially.

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Keywords

CCS Concepts, • Computing methodologies → Ray tracing

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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