“…Recently there has been an explosion of interest into CNNs with predefined transformation equivariances, beyond translation [2,3,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] [20, 21,22,23]. However, with the exception of Cohen and Welling [23] (projections on sphere), Kondor [22] (point clouds), and Thomas et al [20] (point clouds), these have mainly focused on the 2D scenario.…”