Papers › Moser Flow: Divergence-based Generative Modeling on Manifolds

Moser Flow: Divergence-based Generative Modeling on Manifolds

18 Aug 2021NeurIPS 2021 12arXiv:2108.08052archive 2025-07-28

Noam Rozen, Aditya Grover, Maximilian Nickel, Yaron Lipman

We are interested in learning generative models for complex geometries described via manifolds, such as spheres, tori, and other implicit surfaces. Current extensions of existing (Euclidean) generative models are restricted to specific geometries and typically suffer from high computational costs. We introduce Moser Flow (MF), a new class of generative models within the family of continuous normalizing flows (CNF). MF also produces a CNF via a solution to the change-of-variable formula, however differently from other CNF methods, its model (learned) density is parameterized as the source (prior) density minus the divergence of a neural network (NN). The divergence is a local, linear differential operator, easy to approximate and calculate on manifolds. Therefore, unlike other CNFs, MF does not require invoking or backpropagating through an ODE solver during training. Furthermore, representing the model density explicitly as the divergence of a NN rather than as a solution of an ODE facilitates learning high fidelity densities. Theoretically, we prove that MF constitutes a universal density approximator under suitable assumptions. Empirically, we demonstrate for the first time the use of flow models for sampling from general curved surfaces and achieve significant improvements in density estimation, sample quality, and training complexity over existing CNFs on challenging synthetic geometries and real-world benchmarks from the earth and climate sciences.

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build_mlp noamroze/moser_flow/common/architectures.py official repository unverified MIT (permissive) · afc8000701215633 · report
evaluate_checkpoints noamroze/moser_flow/evaluate_time.py official repository unverified MIT (permissive) · fc72d67983e81dbc · report
evaluate_checkpoints noamroze/moser_flow/run_statistical_experiment.py official repository unverified MIT (permissive) · f8e51601051c0f50 · report
exact_divergence noamroze/moser_flow/common/estimators.py official repository unverified MIT (permissive) · b66e58e39476d143 · report
get_train_metrics noamroze/moser_flow/evaluate_time.py official repository unverified MIT (permissive) · 0fe9dd806a092065 · report
get_val_metrics noamroze/moser_flow/evaluate_time.py official repository unverified MIT (permissive) · 8fce565bb01c92df · report
parse_activation noamroze/moser_flow/common/architectures.py official repository unverified MIT (permissive) · f27216ea9fe2e0a5 · report
slice_size noamroze/moser_flow/datasets.py official repository unverified MIT (permissive) · 720fe92efdb3bac0 · report

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Density Estimation

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Methods

Normalizing Flows

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