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A. Celarek, W. Jakob, M. Wimmer, J. Lehtinen:
"Quantifying the Error of Light Transport Algorithms";
Talk: EGSR 2019 : Eurographics Symposium on Rendering, Strasbourg, France |; 2019-07-10 - 2019-07-12; in: "Computer Graphics Forum", Computer Graphics Forum, Volume: 38, Issue 4 (2019), 111 - 121.

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.

measuring error, light transport, global illumination

http://dx.doi.org/10.1111/cgf.13775

https://publik.tuwien.ac.at/files/publik_282852.pdf