Many variants of the Wasserstein distance have been introduced to reduce its original computational burden. In particular the Sliced-Wasserstein distance (SW), which leverages one-dimensional projections for which a closed-form solution of the Wasserstein distance is available, has received a lot of interest. Yet, it is restricted to data living in Euclidean spaces, while the Wasserstein distance has been studied and used recently on manifolds. We focus more specifically on the sphere, for which we define a novel SW discrepancy, which we call spherical Sliced-Wasserstein, making a first step towards defining SW discrepancies on manifolds. Our construction is notably based on closed-form solutions of the Wasserstein distance on the circle, together with a new spherical Radon transform. Along with efficient algorithms and the corresponding implementations, we illustrate its properties in several machine learning use cases where spherical representations of data are at stake: density estimation on the sphere, variational inference or hyperspherical auto-encoders.

本文介绍了一种新的基于球面的Sliced-Wasserstein距离测度方法，该方法基于对圆上Wasserstein距离的封闭解和球面Radon变换的新构建，从而使得SW的差异测量得以扩展至流形，同时该方法的高效实现有助于在球面数据表示的机器学习应用中实现样本采样、密度估计和超球自编码器等。

球形切片-瓦热斯坦