Scale-invariant Learning by Physics Inversion

Philipp Holl, Vladlen Koltun, Nils Thuerey

Keywords: Higher-order Optimization, Neural Networks, Inverse Problems, Physical Simulations

TL;DR: We combine scale invariant physics optimizers with Adam to improve learning ill-conditioned inverse problems.

Abstract:

Solving inverse problems, such as parameter estimation and optimal control, is a vital part of science. Many experiments repeatedly collect data and rely on machine learning algorithms to quickly infer solutions to the associated inverse problems. We find that state-of-the-art training techniques are not well-suited to many problems that involve physical processes. The highly nonlinear behavior, common in physical processes, results in strongly varying gradients that lead first-order optimizers like SGD or Adam to compute suboptimal optimization directions.
We propose a novel hybrid training approach that combines higher-order optimization methods with machine learning techniques. We take updates from a scale-invariant inverse problem solver and embed them into the gradient-descent-based learning pipeline, replacing the regular gradient of the physical process.
We demonstrate the capabilities of our method on a variety of canonical physical systems, showing that it yields significant improvements on a wide range of optimization and learning problems.