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We develop a measure for evaluating the performance of generative networks given two sets of images. A popular performance measure currently used to do this is the Fréchet Inception Distance (FID). FID assumes that images featurized using the penultimate layer of Inception-v3 follow a Gaussian distribution, an assumption which cannot be violated if we wish to use FID as a metric. However, we show that Inception-v3 features of the ImageNet dataset are not Gaussian; in particular, every single marginal is not Gaussian. To remedy this problem, we model the featurized images using Gaussian mixture models (GMMs) and compute the 2-Wasserstein distance restricted to GMMs. We define a performance measure, which we call WaM, on two sets of images by using Inception-v3 (or another classifier) to featurize the images, estimate two GMMs, and use the restricted 2-Wasserstein distance to compare the GMMs. We experimentally show the advantages of WaM over FID, including how FID is more sensitive than WaM to imperceptible image perturbations. By modelling the non-Gaussian features obtained from Inception-v3 as GMMs and using a GMM metric, we can more accurately evaluate generative network performance.
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Discrete-Continuous Gaussian Mixture Models for Wind Power Generation
Gaussian Mixture Models (GMM) are an effective representation of resource uncertainty in power systems planning, as they can be tractably incorporated within stochastic optimization models. However, the skewness, multimodality, and bounded physical support of long-term wind power forecasts can entail requiring a large number of mixture components to achieve a good fit, leading to complex optimization problems. We propose a probabilistic model for wind generation uncertainty to address this challenge, termed Discrete-Gaussian Mixture Model (DGMM), that combines continuous Gaussian components with discrete masses. The model generalizes classical GMMs that have been widely used to estimate wind power outputs. We employ a modified Expectation-Maximization algorithm (called FixedEM) to estimate the parameters of the DGMM. We provide empirical results on the ACTIVSg2000 synthetic wind generation dataset, where we demonstrate that the fitted DGMM is capable of capturing the high frequencies of time windows when wind generating units are either producing at maximum capacity or not producing any power at all. Furthermore, we find that the Bayesian Information Criterion of the DGMM is significantly lower compared to that of existing GMMs using the same number of Gaussian components. This improvement is particularly advantageous when the allowed number of Gaussian components is limited, facilitating the efficient solution to optimization problems for long-term planning.
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- PAR ID:
- 10557085
- Publisher / Repository:
- IEEE
- Date Published:
- Journal Name:
- IEEE Power Energy Society General Meeting
- ISSN:
- 1944-9933
- ISBN:
- 979-8-3503-8183-2
- Page Range / eLocation ID:
- 1-5
- Format(s):
- Medium: X
- Location:
- Seattle, WA, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/PESGM51994.2024.10761067
