Poster
Poisson Flow Generative Models
Yilun Xu · Ziming Liu · Max Tegmark · Tommi Jaakkola
Hall J (level 1) #732
Keywords: [ poisson equation ] [ generative model ] [ ODE ]
Abstract:
We propose a new "Poisson flow" generative model~(PFGM) that maps a uniform distribution on a high-dimensional hemisphere into any data distribution. We interpret the data points as electrical charges on the hyperplane in a space augmented with an additional dimension , generating a high-dimensional electric field (the gradient of the solution to Poisson equation). We prove that if these charges flow upward along electric field lines, their initial distribution in the plane transforms into a distribution on the hemisphere of radius that becomes uniform in the limit. To learn the bijective transformation, we estimate the normalized field in the augmented space. For sampling, we devise a backward ODE that is anchored by the physically meaningful additional dimension: the samples hit the (unaugmented) data manifold when the reaches zero. Experimentally, PFGM achieves current state-of-the-art performance among the normalizing flow models on CIFAR-10, with an Inception score of and a FID score of . It also performs on par with the state-of-the-art SDE approaches while offering to acceleration on image generation tasks. Additionally, PFGM appears more tolerant of estimation errors on a weaker network architecture and robust to the step size in the Euler method. The code is available at https://github.com/Newbeeer/poisson_flow .
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