DeepSphere: a graph-based spherical CNN
Authors: Michaël Defferrard, Martino Milani, Frédérick Gusset, Nathanaël Perraudin
Keywords: spherical cnns, graph neural networks, geometric deep learning
TL;DR: A graph-based spherical CNN that strikes an interesting balance of trade-offs for a wide variety of applications.
Abstract: Designing a convolution for a spherical neural network requires a delicate tradeoff between efficiency and rotation equivariance. DeepSphere, a method based on a graph representation of the discretized sphere, strikes a controllable balance between these two desiderata. This contribution is twofold. First, we study both theoretically and empirically how equivariance is affected by the underlying graph with respect to the number of pixels and neighbors. Second, we evaluate DeepSphere on relevant problems. Experiments show state-of-the-art performance and demonstrates the efficiency and flexibility of this formulation. Perhaps surprisingly, comparison with previous work suggests that anisotropic filters might be an unnecessary price to pay. Our code is available at https://github.com/deepsphere.